A deep dive into management of cardiac arrhythmia from a Critical Care perspective. Covers brady- and tachyarrhythmias and management of both the stable and unstable patient.
AV nodal reentrant tachycardia (AVNRT), or atrioventricular nodal reentrant tachycardia, is a type of tachycardia (fast rhythm) of the heart. It is a type of supraventricular tachycardia (SVT), meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia. It is more common in women than men (approximately 75% of cases occur in females). The main symptom is palpitations. Treatment may be with specific physical maneuvers, medication, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.
AVNRT occurs when a reentry circuit forms within or just next to the atrioventricular node. The circuit usually involves two anatomical pathways: the fast pathway and the slow pathway, which are both in the right atrium. The slow pathway (which is usually targeted for ablation) is located inferior and slightly posterior to the AV node, often following the anterior margin of the coronary sinus. The fast pathway is usually located just superior and posterior to the AV node. These pathways are formed from tissue that behaves very much like the AV node, and some authors regard them as part of the AV node.
The fast and slow pathways should not be confused with the accessory pathways that give rise to Wolff-Parkinson-White syndrome (WPW syndrome) or atrioventricular reciprocating tachycardia (AVRT). In AVNRT, the fast and slow pathways are located within the right atrium close to or within the AV node and exhibit electrophysiologic properties similar to AV nodal tissue. Accessory pathways that give rise to WPW syndrome and AVRT are located in the atrioventricular valvular rings. They provide a direct connection between the atria and ventricles, and have electrophysiologic properties similar to ventricular myocardium.
AV nodal reentrant tachycardia (AVNRT), or atrioventricular nodal reentrant tachycardia, is a type of tachycardia (fast rhythm) of the heart. It is a type of supraventricular tachycardia (SVT), meaning that it originates from a location within the heart above the bundle of His. AV nodal reentrant tachycardia is the most common regular supraventricular tachycardia. It is more common in women than men (approximately 75% of cases occur in females). The main symptom is palpitations. Treatment may be with specific physical maneuvers, medication, or, rarely, synchronized cardioversion. Frequent attacks may require radiofrequency ablation, in which the abnormally conducting tissue in the heart is destroyed.
AVNRT occurs when a reentry circuit forms within or just next to the atrioventricular node. The circuit usually involves two anatomical pathways: the fast pathway and the slow pathway, which are both in the right atrium. The slow pathway (which is usually targeted for ablation) is located inferior and slightly posterior to the AV node, often following the anterior margin of the coronary sinus. The fast pathway is usually located just superior and posterior to the AV node. These pathways are formed from tissue that behaves very much like the AV node, and some authors regard them as part of the AV node.
The fast and slow pathways should not be confused with the accessory pathways that give rise to Wolff-Parkinson-White syndrome (WPW syndrome) or atrioventricular reciprocating tachycardia (AVRT). In AVNRT, the fast and slow pathways are located within the right atrium close to or within the AV node and exhibit electrophysiologic properties similar to AV nodal tissue. Accessory pathways that give rise to WPW syndrome and AVRT are located in the atrioventricular valvular rings. They provide a direct connection between the atria and ventricles, and have electrophysiologic properties similar to ventricular myocardium.
Its a medical presentation describing how to approach to various cardiac arrhythmias in systematic way. Illustrated with more ECG photographs from standard sources.
Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the conduction system of the heart that are commonly referred to as pre-excitation syndromes. WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals travelling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely, resulting in a unique type of supraventricular tachycardia referred to as an atrioventricular reciprocating tachycardia.The incidence of WPW is between 0.1% and 0.3% in the general population.Sudden cardiac death in people with WPW is rare (incidence of less than 0.6%), and is usually caused by the propagation of an atrial tachydysrhythmia (rapid and abnormal heart rate) to the ventricles by the abnormal accessory pathway.
This presentation describes the emergency department management of sinus tachycardia, supraventricular tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia and ventricular ectopic
Its a medical presentation describing how to approach to various cardiac arrhythmias in systematic way. Illustrated with more ECG photographs from standard sources.
Wolff–Parkinson–White syndrome (WPW) is one of several disorders of the conduction system of the heart that are commonly referred to as pre-excitation syndromes. WPW is caused by the presence of an abnormal accessory electrical conduction pathway between the atria and the ventricles. Electrical signals travelling down this abnormal pathway (known as the bundle of Kent) may stimulate the ventricles to contract prematurely, resulting in a unique type of supraventricular tachycardia referred to as an atrioventricular reciprocating tachycardia.The incidence of WPW is between 0.1% and 0.3% in the general population.Sudden cardiac death in people with WPW is rare (incidence of less than 0.6%), and is usually caused by the propagation of an atrial tachydysrhythmia (rapid and abnormal heart rate) to the ventricles by the abnormal accessory pathway.
This presentation describes the emergency department management of sinus tachycardia, supraventricular tachycardia, atrial flutter, atrial fibrillation, ventricular tachycardia and ventricular ectopic
This presentation is a simplified version of the various types of cardiac arrythmias seen in pediatric age groups. We have discussed supraventricular tachycarsias and prolonged QT syndrome in details here. Hope everyone finds it useful.
cardiac arrhythmias are abnormal heart rhythms that occur when the electrical signals controlling the heart beat are not working properly.
these can include tachycardia ,Bradycardia,atrial fibrillation and more.
Another Critical Care Collaborative Deep Dive into the assessment and management of shock. Covers classification of shock, diagnosis, serial assessment methods and management.
The third presentation in my ACEM Fellowship Summary series. Focuses on the aetiology, diagnosis and management of acute heart failure in its many forms.
Global launch of the Healthy Ageing and Prevention Index 2nd wave – alongside...ILC- UK
The Healthy Ageing and Prevention Index is an online tool created by ILC that ranks countries on six metrics including, life span, health span, work span, income, environmental performance, and happiness. The Index helps us understand how well countries have adapted to longevity and inform decision makers on what must be done to maximise the economic benefits that comes with living well for longer.
Alongside the 77th World Health Assembly in Geneva on 28 May 2024, we launched the second version of our Index, allowing us to track progress and give new insights into what needs to be done to keep populations healthier for longer.
The speakers included:
Professor Orazio Schillaci, Minister of Health, Italy
Dr Hans Groth, Chairman of the Board, World Demographic & Ageing Forum
Professor Ilona Kickbusch, Founder and Chair, Global Health Centre, Geneva Graduate Institute and co-chair, World Health Summit Council
Dr Natasha Azzopardi Muscat, Director, Country Health Policies and Systems Division, World Health Organisation EURO
Dr Marta Lomazzi, Executive Manager, World Federation of Public Health Associations
Dr Shyam Bishen, Head, Centre for Health and Healthcare and Member of the Executive Committee, World Economic Forum
Dr Karin Tegmark Wisell, Director General, Public Health Agency of Sweden
The dimensions of healthcare quality refer to various attributes or aspects that define the standard of healthcare services. These dimensions are used to evaluate, measure, and improve the quality of care provided to patients. A comprehensive understanding of these dimensions ensures that healthcare systems can address various aspects of patient care effectively and holistically. Dimensions of Healthcare Quality and Performance of care include the following; Appropriateness, Availability, Competence, Continuity, Effectiveness, Efficiency, Efficacy, Prevention, Respect and Care, Safety as well as Timeliness.
Explore our infographic on 'Essential Metrics for Palliative Care Management' which highlights key performance indicators crucial for enhancing the quality and efficiency of palliative care services.
This visual guide breaks down important metrics across four categories: Patient-Centered Metrics, Care Efficiency Metrics, Quality of Life Metrics, and Staff Metrics. Each section is designed to help healthcare professionals monitor and improve care delivery for patients facing serious illnesses. Understand how to implement these metrics in your palliative care practices for better outcomes and higher satisfaction levels.
CHAPTER 1 SEMESTER V PREVENTIVE-PEDIATRICS.pdfSachin Sharma
This content provides an overview of preventive pediatrics. It defines preventive pediatrics as preventing disease and promoting children's physical, mental, and social well-being to achieve positive health. It discusses antenatal, postnatal, and social preventive pediatrics. It also covers various child health programs like immunization, breastfeeding, ICDS, and the roles of organizations like WHO, UNICEF, and nurses in preventive pediatrics.
R3 Stem Cells and Kidney Repair A New Horizon in Nephrology.pptxR3 Stem Cell
R3 Stem Cells and Kidney Repair: A New Horizon in Nephrology" explores groundbreaking advancements in the use of R3 stem cells for kidney disease treatment. This insightful piece delves into the potential of these cells to regenerate damaged kidney tissue, offering new hope for patients and reshaping the future of nephrology.
CRISPR-Cas9, a revolutionary gene-editing tool, holds immense potential to reshape medicine, agriculture, and our understanding of life. But like any powerful tool, it comes with ethical considerations.
Unveiling CRISPR: This naturally occurring bacterial defense system (crRNA & Cas9 protein) fights viruses. Scientists repurposed it for precise gene editing (correction, deletion, insertion) by targeting specific DNA sequences.
The Promise: CRISPR offers exciting possibilities:
Gene Therapy: Correcting genetic diseases like cystic fibrosis.
Agriculture: Engineering crops resistant to pests and harsh environments.
Research: Studying gene function to unlock new knowledge.
The Peril: Ethical concerns demand attention:
Off-target Effects: Unintended DNA edits can have unforeseen consequences.
Eugenics: Misusing CRISPR for designer babies raises social and ethical questions.
Equity: High costs could limit access to this potentially life-saving technology.
The Path Forward: Responsible development is crucial:
International Collaboration: Clear guidelines are needed for research and human trials.
Public Education: Open discussions ensure informed decisions about CRISPR.
Prioritize Safety and Ethics: Safety and ethical principles must be paramount.
CRISPR offers a powerful tool for a better future, but responsible development and addressing ethical concerns are essential. By prioritizing safety, fostering open dialogue, and ensuring equitable access, we can harness CRISPR's power for the benefit of all. (2998 characters)
How many patients does case series should have In comparison to case reports.pdfpubrica101
Pubrica’s team of researchers and writers create scientific and medical research articles, which may be important resources for authors and practitioners. Pubrica medical writers assist you in creating and revising the introduction by alerting the reader to gaps in the chosen study subject. Our professionals understand the order in which the hypothesis topic is followed by the broad subject, the issue, and the backdrop.
https://pubrica.com/academy/case-study-or-series/how-many-patients-does-case-series-should-have-in-comparison-to-case-reports/
2. Introduction
Regular rhythm has <10% variation in beat-to-beat length
Check by marking off 5 beats and moving
Conduction defects
Bundle branch blocks: Pre-existing or rate-related
Accessory pathways
Hyperkalaemia
Sodium channel blockade
Pacing
3. The bradycardic unstable patient
Transcutaneous pacing is Class I treatment
Most patients achieve capture at 100mA
Start at lowest current that achieves capture
IV narcotics/benzodiazepines are necessary
Atropine is Class IIA treatment
500mcg q5min IV until desired response achieved (up to 3mg)
Transient effect so prepare for transcutaneous/venous pacing
Use cautiously in ischaemia
Can be used cautiously in heart transplant patients but often no response due to lack of vagal
innervation
Adrenaline 2-10mcg/min IV infusion
Dopamine 2-10mcg/kg/min IV infusion
4. The tachycardic unstable patient
Synchronised cardioversion applies current well away from vulnerable period of
inducing VF (10ms after peak of R wave) (for all others)
Defibrillation applies current as soon as button pressed (for VF)
200J either way
Complications
Myocardial damage (rare if <325 J)
Induced arrhythmias
More likely if on digoxin, quinidine, electrolyte abnormalities or MI
Thromboembolism
1.2-1.5% of chronic AF patients (if unstable risk outweighed by benefit)
Hypotension
5. Stable narrow-complex tachycardia
Regular
Attempt vagal manoeuvres (10mL syringe)
Adenosine 6mg IV, 12mg IV, 12mg IV
If converts
Likely AVRT or AvnRT
Does not convert
Likely atrial flutter, ectopical atrial tachycardia, junctional tachycardia
Control rate and consider underlying cause and manage accordingly
Irregular
Probable AF, atrial flutter or MAT
Control rate and consider underlying cause and manage accordingly
6. Stable wide-complex tachyarrhythmia
Regular rhythm
Possible VT or unknown
Amiodarone 150mg IV over 10 min
Repeat if necessary to total 2.2g over 24 hours
Prepare for synchronised cardioversion
Definite SVT with aberrancy
Treat as for SVT
7. Stable wide-complex tachyarrhythmia
Irregular rhythm
WPW with AF
Avoid AV nodal blockers
Consider amiodarone and expert consultation
Torsades de pointe
Magnesium 1-2g over 5-60min
Polymorphic VT
Prepare for synchronised cardioversion
AF with aberrancy
Follow narrow complex irregular algorithm
8. Sinus arrhythmia
Definition
Variation >0.12s between longest and shortest P-P interval
Normal sinus P waves and P-R intervals
1:1 AV conduction
Normal finding in young people often due to Bainbridge reflex (vagal tone changes
with respiration)
No treatment required
9. Premature atrial contractions
Definition
Ectopic P wave that appears before next expected sinus beat
Ectopic P wave that has a different shape and axis
Ectopic P wave may or may not be conducted through AV node (depends if reaches AV node
in absolute refractory period (not conducted) or in relative refractory period (delayed
conduction – long PR))
May conduct aberrantly if reaches bundle branch while still in refractory period
Common at all ages and usually do not indicate cardiac disease
Frequent PAC’s seen in chronic lung disease, IHD, digitalis toxicity, increased stress,
caffeine, tobacco
May precipitate sustained atrial tachycardia, flutter or fibrillation
Treatment
Cease any toxins and treat any underlying disorder, if present
10. Bradydysrhythmias
Bradycardia (ventricle and atria at same slow rates)
Includes sinus bradycardia, junctional rhythm, idioventricular rhythm and hyperkalaemia-
related sinoventricular rhythm
AV blocks
Second-degree AV block (usually type 2), 3rd degree AV block, slow AF/flutter
80% of bradydysrhythmias are due to factors outside the conduction system e.g.
toxicity, ACS, hypoxia
Emergent treatment is only required if:
HR <50 and accompanied by hypotension or hypoperfusion OR
Needs resuscitative treatment
Structural disease of the infranodal system
Needs close monitoring and pacing available at all times
11. Bradydysrhythmias
Atropine
Vagolytic
Effective for sinus bradycardia and junctional rhythms but not useful (nor particularly
harmful) for idioventricular rhythms, second-degree type 2 or third-degree AV block
12. Sinus bradycardia
Definition:
Normal sinus P waves and P-R intervals
1:1 AV conduction
Atrial rate <60/min
May be:
Physiological (e.g. athletes)
Pharmacological (e.g. digoxin, opioids, beta-blocker, CCB)
Pathological (e.g. acute inferior MI, raised ICP, carotid sinus hypersensitivity or
hypothyroidism)
Treat if signs of hypoperfusion and <50 as per algorithm
13. Sick sinus syndrome
Heterogenous group of diseases causing intermittent tachy- and bradyarrhythmias
Tachyarrhythmias usually: AF, junctional tachycardia, SVT or atrial flutter
Bradyarrhythmias usually: Sinus bradycardia, prolonged sinus arrest, SA block
usually with AV nodal block and inadequate AV nodal escape rhythms
Causes
Ischaemia, rheumatic disorders, myocarditis, pericarditis, metastatic tumors, surgical
damage and cardiomyopathies
Symptoms
Syncope, near syncope, palpitations, dyspnoea, chest pain or CVA
14. Sick sinus syndrome
Exacerbating factors
Disease: Abdominal pain, raised ICP, thyrotoxicosis, hyperkalaemia, increased vagal tone
Drugs: Beta-blockers, CCB, digoxin, quinidine, procainamide, disopyramide
Diagnosis often requires Holter monitoring
Treatment: Avoid antiarrhythmics as worsen one or the other part
NEED PACEMAKER URGENTLY
15. Sinus tachycardia
Definition:
Normal sinus P waves and P-R intervals
1:1 AV conduction
Atrial rate usually 100-160
Physiological: Children, exercise, anxiety, emotion
Pharmacological: Atropine, salbutamol, adrenaline, alcohol, nicotine, caffeine
Pathological: Sepsis, pain, fever, hypoxia, anaemia, hypovolaemia, PE
Treat underlying disorder ONLY
16. SVT
Defined as any tachyarrhythmia arising from above AV node
Commonly describes AVRT and AvnRT
60% have AvnRT and 20% have AVRT (involving bypass tract)
The rest have re-entry involving some other site
Occurs in 2% of patients after AMI
HR usually 150-200J in adult
Rates >220 suggest accessory pathway (AVRT)
In a normal heart, rates of 160-200 may be tolerated for days
17. SVT - ECG
p waves
May be seen in latter part of QRS in lead V1 in 30% of AVNRT
Indicates typical slow-fast AVNRT with short R-P interval
If later in the T wave, suggests fast-slow AVNRT with long R-P interval
More commonly seen in AVRT
ST elevation in aVR – 70% sensitive and specific for accessory pathway
ST depression is common and not predictive of IHD
ST-T wave changes can persist for days following reversion
Electrical alternans seen in 20% of SVT and is not predictive of pericardial effusion
19. SVT - AVnRT
Re-entry circuit within AV node
60% of cases
Initiated by ectopic atrial impulse reaching AV node in relative refractory period
Mostly slow-fast (i.e. slow antegrade and fast retrograde conduction)
ECG characteristics
P wave buried in QRS complex and usually not visible
1:1 conduction
Normal QRS complex
Causes
Normal heart
Rheumatic heart disease, acute MI, acute pericarditis, mitral valve prolapse or a pre-excitation syndrome
Pregnant patients with tachyarrhythmias have a higher rate of foetal distress
20. SVT - AVnRT
Treatment
Vagal manoeuvres (success rate 20-25%)
15% without augmentation and 40% with augmentation
Valsalva in supine position is most effective (need strain for at least 10 seconds) using 10mL
syringe
Ice pack on face reserved for infants with 6-7 seconds and nose held closed (diving reflex)
Carotid sinus massage
10 seconds at a time, first on non-dominant cerebral hemisphere
Never bilateral
CI: Known AV nodal block, digoxin or carotid artery stenosis
21. SVT
Adenosine
>90% of re-entrant SVT converted but 1/3 revert back. Increased efficacy if higher heart rate
This is the only Class I therapy
First choice if infants, structural heart disease or borderline perfusion
Elimination half-life 10 seconds
50% suffer facial flushing, distress and chest pain
Early recurrence seen in 25% of patients
6mg then 12mg
Potentiated by carbamazepine and dipyramidole so use 3mg (blocks nucleoside transport into cells)
Theophylline and caffeine antagonise effect at adenosine receptors so use higher dose
20% reduced reversion rate if caffeine in last 4 hours
Also use lower dose if central line or heart transplant patients
Initially cleared from serum rapidly by intracellular uptake (nucleoside transporter) then deamination by adenosine
deaminase in cytosol or phophorylation by adnosine kinase
Not contraindicated in WPW when QRS is narrow
22. SVT - AvnRT
Verapamil and diltiazem are second-line therapy (Class IIA)
Diltiazem 15-20mg IV over 2 min then continuous infusion 4-20mg/hr
Can repeat bolus in 15 min if needed
Verapamil 2.5-5mg IV over 2 min, can repeat at 15min if necessary
First choice if young adult without structural heart disease and narrow QRS
Reversion rate 80% with 5mg and 95% with 10mg
Progressively less effective for HR >175
Probably more effective than adenosine if caffeine ingested in last 4 hours
Pre-treatment with 5mL of 10% calcium gluconate decreases hypotensive effects without impairing
cardioversion success
CI: CCF or COAD
Calcium should be available – 500-1000mg IV of calcium chloride q10min if necessary
Mean SBP drop of 20mmHg and MAP drop of 10mmHg with verapamil
23. SVT
Beta-blockers
Class IIA recommendation also
Metoprolol 5mg IV q5min up to 3 doses
Esmolol 500mcg/kg IV over 1 min. Can repeat after 2-5min then infusion 50mcg/kg/min
Propranolol 0.1mg/kg divided into 3 equal doses given slowly 2 min apart
CI: CCF or COAD
Esmolol effective in 50% of re-entrant SVT
Hypotension seen in 50% but rapidly reversible if esmolol used
Propranolol IV also 50% success rate (80% with AvnRT and 15-20% with accessory pathway
AVRT)
Electrical cardioversion rarely required (20-100J biphasic)
24. SVT - Prophylaxis
Flecainide
Digoxin and verapamil in combination
Need high doses
Radiofrequency ablation of accessory pathways
25. SVT - AVRT
Re-entry usually occurs with antegrade conduction via AV node (hence narrow
complex – orthodromic conduction)
85% of re-entrant SVT seen with WPW are narrow complex (orthodromic)
Retrograde P wave is often seen after the QRS as arises from atrial stimulation via
retrograde accessory pathway transmission
Inverted in II, III, aVF (as arising from Bundle vs. sinus node)
Antidromic conduction results in wide complex tachy-arrhythmias that are difficult
to differentiate from VT
Only 5% of accessory pathways are in this
26. SVT - AVRT
Types
Lown-Ganong-Levine syndrome
James fibres (atriohisian connection)
Continuation of posterior internodal tract connecting atrium with proximal His bundles
Usual delay in AV node is bypassed
Get short PR as a result with normal QRS (as still initiated from Bundle of His)
No Delta wave
27. SVT - AVRT
Types continued
Mahaim bundles
Bundles of myogenic tissue
Impulses go via AV node but then some impulses bypass infranodal conducting system
Get ventricular activation from two sources simultaneously – bypass tract and normal conducting system
Results in delta wave then normal QRS after this
Kent bundles
Myogenic tissue bypassing AV node altogether
Most common source for WPW syndrome
Short PR (<120ms), delta wave, broad QRS >100ms
Repolarisation abnormalities occur due to altered depolarisation and include ST and T wave discordant
changes
28. SVT – AVRT
Paroxysmal re-entrant SVT occurs in 40-80% of WPW patients
AF in 10-20% of WPW patients
Atrial flutter in 5% of WPW patients
Most patients with WPW have longer refractory periods in bypass tract than AV node (but minority have opposite)
Can result in wide complex tachycardia transmitting atrial fib/flutter at 1:1
Any patient with a ventricular rate >300 should raise suspicion of pre-excitation syndrome
Treatment
Narrow-complex orthodromic AVRT treated like AvnRT
As AV node is involved, any AV nodal blocking agent will help
Wide-complex antidromic AVRT is usually associated with a short refractory period in the bypass tract, with high risk of rapid
ventricular rates and VF
AVOID beta-blockers, CCB and adenosine
Best treated with cardioversion
Amiodarone and flecainide are options with Cardiology input
29. WPW
SVT with WPW
Verapamil contraindicated when antidromic conduction present as may convert atrial rate to
ventricular rate and precipitate VF
AF with WPW
Flecainide
Drug of choice if structurally normal heart w/o CAD
Slow conduction in accessory pathway
150mg IV over 30 minutes (2mg/kg)
Electrical cardioversion
If unstable or flecainide contraindicated
Adenosine
Unlikely to be of benefit and may enhance ventricular response through AV blockade
Verapamil and digoxin enhance conduction via accessory pathway and are CI
30. WPW
1-2% of patients with WPW actually present with an arrhythmia
80% AVRT
15-30% AF
5% A flutter
1-3% of population have accessory pathways
Can have pseudo-old infarction pattern
31. Atrial flutter
Exact mechanism unknown
ECG characteristics
Regular atrial rate of 250-350
Sawtooth flutter waves – superiorly directed and most easily seen in II, III, aVF (usually inverted)
AV block, usually 2:1 and ventricular rate 125-175
There is no isoelectric segment
Often flutter waves only visible in one lead
Flutter wave and QRS ALWAYS meet above the baseline
May transmit 1:1 if bypass tract or atrial rate slowed by medications to allow AV nodal
conduction
Often better tolerated than AF at high ventricular rates due to organised atrial actiity
32. Atrial flutter
Causes
Ischaemic heart disease
Acute MI (occurs in 2% of AMI)
Congestive cardiomyopathy
PE
Myocarditis
Blunt chest trauma
Digoxin toxicity
33. Atrial flutter
Diagnostic manoeuvres if flutter waves difficult to identify (e.g. adenosine)
Management
Chemical cardioversion rarely successful
Verapamil 10% (but 90% effective if AMI-related)
Electrical cardioversion
50J will cardiovert 80%
100J will cardiovert 95%
Atrial overdrive pacing (>400) an option
Anticoagulate as for AF
Rate control as for AF
Conservative approach waiting for reversion is often appropriate if 2:1 block
34. Atrial fibrillation
Most common sustained arrhythmia – lifetime risk over 40yo = 25%
0.4-2% of population
4% if over 60, 7% if over 65, >10% if >85yo
1.6% per annum if over 75
Causes 25% of strokes in patients >80yo
90% of ‘lone fibrillators’ revert within 48 hours and 60% will cardiovert with 100J
ECG characteristics
Atrial fibrillation waves – best seen in V1,2,3, aVF
Irregularly irregular ventricular response
QRS <120ms unless pre-existing BBB, accessory pathway or rate-related BBB
Usual ventricular response is 140-180/min but slower in diseased AV node or AV nodal blocking agents
More rapid ventricular response may be seen in bypass tracts
Asymptomatic in 20%
35. Atrial fibrillation
Predisposing factors
Increased atrial size and mass
Usually one of four conditions underlying:
Rheumatic heart disease
IHD (40%)
Thyrotoxicosis
HTN
Also
Chronic lung disease
Pericarditis
Acute alcohol intoxication (holiday heart – high spontaneous reversion rate)
PE
Atrial septal defect
Clinical hyperthyroidism in 1%
36. AF
Classification
Primary
Secondary (30%)
Recurrent (>=2 episodes)
Paroxysmal (terminates spontaneously or with intervention within 7 days)
Sustained (>7 days)
Occult (only with prolonged ECG monitoring)
Long-standing (>1 year and rhythm control attempted)
Permanent (attempts at rhythm control abandoned)
Non-valvular AF – Absence of:
Rheumatic mitral disease
Mechanical or bioprosthetic heart valve
Mitral valve repair
37. AF
Observation strategy
Usually the least appropriate if RVR
Indications
Holiday heart
Acute stimulant intoxication (benzos first-line)
Significant underlying heart disease with stress response e.g. febrile
Unlikely to respond to chemical rhythm control and chemical rate control poses risk of
cardiac decompensation
If haemodynamically stable, treat underlying cause and reconsider strategy at 48 hours
If rhythm control required, electrical is method of choice
38. AF
Spontaneous reversion
<1 hour: 25%
<6 hours: 40%
<24 hours: 50%
<48 hours: 65%
>1 week: Rare
Without anticoagulation therapy
Up to 5% of patients with chronic AF have at least one embolic episode each year
Conversion from chronic AF to sinus rhythm carries 1-5% risk of arterial embolism
39. Atrial fibrillation
Treatment
If stable, rate control is first priority to resting HR of <110
If no evidence of CCF or a bypass tract:
Beta-blockers: Metoprolol 5mg IV q5min up to 15mg or esmolol or propranolol
CCB: Diltiazem 15-20mg IV over 2 min, followed by infusion 4-20mg/hr
IV amiodarone second-line: 5mg/kg IV over 30-60min followed by 15mg/kg/day infusion (can cause
cardioversion though)
Can add digoxin if fails
If CCF evident (LVEF <40%) but no bypass tract:
IV digoxin or amiodarone (CI in pregnancy)
Digoxin 400-600mcg IV loading dose repeated at 4-6 hours
If accessory pathway evident:
DC cardioversion, amiodarone or flecainide are options
40. Atrial fibrillation
Rate control
Potential candidates
Age >65
Sedentary
Asymptomatic
Coronary artery disease
HTN
Large atria
No cardiac failure
Structural heart disease esp. MV
Do not use rate control if HR <90 as suggests intracardiac conduction disturbance and high
risk of severe bradycardia
41. AF
Rate control
Optimum HR depends on diastolic/systolic ratio
70-80: No valve disease, normal coronaries
60-70: AS, MS, LVH, CAD (prolongs diastole)
80-90: AR, MR (shortens diastolic regurg time)
90-115: Sepsis, exercise
Optimum agent: No difference although diltiazem theoretically less likely to cause hypotension
Metoprolol
1mg aliquots up to 5-15mg total IV
Causes less negative inotropy than verapamil
Need early oral therapy to maintain rate control
42. AF
Digoxin
May be no better than placebo (esp. in shock, sepsis, hypoxia)
500mcg slow IV injection then 250mcg q4-6hr to total 1500mcg
43. Atrial fibrillation
Cardioversion
Indicated if unstable OR if <48 hours duration OR if definitively anticoagulated for at least 3
weeks OR if TOE has confirmed no atrial thrombus
Continue for at least 4 weeks after cardioversion (in those not requiring long-term anticoagulation)
Pharmacological cardioversion
Effective in 50% of patients with recent onset AF
Electrical cardioversion is more effective, has shorter hospital stay and is quicker
Does not require sedation or fasting
Severe HF, significant AS – Amiodarone
CAD, moderate HF, abnormal LVH – Amiodarone or Vernakalant
No structural heart disease – IV Flecainide, Ibutilide, Propafenone, Vernakalnt, Procainamide
Procainamide
44. Atrial fibrillation
Cardioversion continued
Electrical cardioversion
85% convert with 100J and >95% if 210J (start with 100J – or 200J if obese)
Can try 4-5 attempts in a row until successful
More likely to be effective if short duration and atria not dilated
Amnesia as important as analgesia (fentanyl + prop)
45. AF
Chemical cardioversion
Amiodarone
5mg/kg IV loading dose over 30-60min (50% by 24 hours, 90% by 48 hours)
Can continue 600mg over 24 hours
Flecainide
2mg/kg IV over 30 minutes
300mg orally if >70kg or 200mg if <70kg
Can repeat
60% reversion within 3 hours and 80% within 8 hours
Not recommended if IHD or structural heart disease or >55yo
Sotalol
Useful if hypertension, CAD with good LV function
Rate control properties probably more beneficial
80-160mg IV or PO
46. Atrial fibrillation
Rhythm control
First choice if new onset AF but risk of thromboembolism
20% lower stroke risk than rate control in the long-term
No survival benefit if older or higher risk patients
55% remain in sinus rhythm at 1 year on treatment (vs. 30% if no treatment)
<50% of those in whom rhythm control is attempted are in sinus rhythm at 5 years
Consider if:
Young
Lone AF
Symptomatic
Secondary to treated or corrected precipitant
Cardiac failure
47. AF
Rhythm control
Risk factors for failed reversion
Age >65
Cardiac failure
Late presentation > 48 hours
Previous AF
Recurrence whilst on antiarrhythmic therapy
Structural cardiac lesions
Left atrial dilation
Secondary AF
48. Atrial fibrillation
Anticoagulation
Bleeding risk with aspirin is same as warfarin and NOACs but aspirin does NOT prevent stroke
Stroke risk/year
0.1% lone fibrillators <60yo with normal echo
5% in AF without structural heart disease
10% in AF with rheumatic heart disease
25% if mitral stenosis
1.5-2.5% if warfarinised or on aspirin
Risk increased 3x in patients with moderate-to-severe LA enlargement
European Society Cardiology
CHADS2-VASC score 0 = No anticoagulation
1 – Anticoagulation should be considered (strongly in men)
2 or more – Anticoagulation indicated
Warfarin if mechanical heart valves or moderate/severe mitral stenosis irrespective of CHADS—VASC score
49. Atrial fibrillation – CHADS2-VASC
CCF +1
HTN >140/90 on at least 2 occasions or current antihypertensive therapy +1
Age 75 or older +2
DM +1
Previous stroke, TIA or thromboembolism +2
Vascular disease +1
Age 65-74 +1
Sex (female) +1
50. AF
Anticoagulation has 60% relative risk reduction for stroke
Absolute risk reduction
2.7% per year for primary prevention
8.4% per year for secondary prevention
25% relative risk reduction of death
1% risk of haemorrhage per year overall
51. Atrial fibrillation - HASBLED
HTN +1
Abnormal LFT/renal fx +1 point each
Stroke +1
Bleeding history or disposition +1
Labile INR +1
Elderly >65yo +1
Drug (NSAID/antiplatelet)/alcohol use +1 point each
54. AF - NOACs
Overall reduce risk of ICH by 0.2%/year vs. warfarin
Increase risk of GI haemorrhage 0.25%/year vs. warfarin
Same risk of ischaemic stroke
Apixaban appears most effective with 0.3%/year lower incidence of stroke and 1%
redution in major bleeding vs. warfarin
Dabigatran is inferior to warfarin if prosthetic valves
DOACs considered appropriate for non-mechanical valvular AF (except rheumatic
MS)
55. Atrial fibrillation – NOAC’s
Apixaban
ARISTOTLE trial 5mg BD reduced embolism by 21% compared to warfarin, 31% reduction in
major bleeding and 11% reduction in all-cause mortality
Rates of haemorrhagic stroke, ICH were lower on apixaban
Rates of GI bleeding were similar
Dabigatran
RE-LY trial 150mg BD reduced embolism by 35% compared with warfarin without a significant
increase in bleeding
GI bleeding increased by 50%
110mg BD was non-inferior to warfarin with 20% fewer bleeding episodes
Edoxaban
ENGAGE AF-TIMI 48 trial 60mg daily non-inferior to warfarin
56. Atrial fibrillation - NOACs
Rivaroxaban
ROCKET-AF trial Non-inferior to warfarin 20mg daily. Did not reduce mortality, ischaemic
stroke or major bleeding
Increased GI bleeding but significant reduction in haemorrhagic stroke and ICH
Meta-analysis
10% lower mortality in NOAC vs. warfarin with significantly reduced ICH and
haemorrhagic stroke
GI haemorrhage 1.25x more llikely on NOAC. ICH halved on NOACs
57. Atrial fibrillation – Left atrial appendage
occlusion
More research needed for Watchman device given high complication rates
May be a suitable alternative for patients with absolute contraindications to
NOAC’s or warfarin OR those who suffer strokes despite anticoagulation
May be interventional or percutaneous
Large randomised control trial of surgical LAA occlusion performed concomitantly
with open heart surgery or AF ablation is underway
58. Atrial fibrillation – Combination antiplatelet
and OAC therapy
Triple therapy dramatically increases bleeding risk
OAC monotherapy without antiplatelets is recommended for stable CAD without ACS and/or
intervention in last 12 months
Short-term triple therapy with OAC, aspirin and clopidogrel recommended for those treated for
ACS
Prasugrel or ticagrelor should be avoided in triple therapy unless a clear need (e.g. stent thrombosis
despite aspirin and clopidogrel)
This is due to increased major bleeding risk compared to clopidogrel
The WOEST trial looked at OAC + clopidogrel vs. triple therapy
Bleeding lower in dual therapy group
Rates of MI, stroke, stent thrombosis did not differ
All-cause mortality lower in dual therapy group at 1 year (2.5 vs 6.4%)
Trial too small but may be future therapy
61. Atrial fibrillation – Management of
bleeding on NOACs or warfarin
APTT useful only for dabigatran
PT for warfarin
Dabigatran cleared by dialysis
If recent intake of NOAC (<2-4hr) activated charcoal can be considered
For warfarin
FFP more rapid than Vitamin K
Prothrombin complex concentrates faster than FFP
Combination offers best chance of survival in ICH
NOAC
Prothrombin complex
Specific antidotes
Idarucizumab humanised antibody fragment for dabigatran
Andexanet alpha, modified human recombinant Factor Xa reverses anti-Xa effect in minutes
63. AF – Long-term Rx
Maintenance of SR if successfully cardioverted
Amiodarone most effective (65% in SR at 1 year)
Sotalol 40% in SR at 1 year
Flecainide
Pill in pocket of 600mg PO intermittently also proven benefit
64. Multifocal atrial tachycardia (MAT)
At least three different site of atrial ectopy
Frequently confused with AF or atrial flutter
ECG characteristics
P waves – 3 or more different morphologies
Changing P-P, P-R and R-R intervals
Atrial rhythm usually 100-180/min
Causes
Typically elderly, COAD, CCF, sepsis or methylxanthine toxicity
Digoxin is an unlikely cause of MAT
Treatment
Directed towards underlying disorder
Cardioversion has no effect on atrial ectopy
Poor prognostic indicator in illness
65. Terminology re: ectopic beats
Compensated pause
If the coupling interval (Interval between normal complex and ectopic complex) + the
return cycle (interval between ectopic complex and next normal complex) is equal to 2x
the dominant cycle interval (regular R-R)
Uncompensated pause
Coupling interval + return cycle is less than 2x DC
66. Junctional arrhythmias
Impulse arises from AV node or Bundle of His above the bifurcation with spread
retrogradely towards atria and anterogradely to ventricles
AV dissociation may occur if junctional escape rate is faster than the sinus node
rate and junctional impulse is blocked from retrograde transmission
P wave often buried in QRS
67. Junctional arrhythmias –
Junctional premature contractions
ECG characteristics
Ectopic P wave different morphology and often inverted in II, III, aVF (i.e. directed
superiorly/retrograde)
Ectopic P wave may lie before or after normal QRS complex
Shorter than normal PR interval
Premature ectopic QRS complex
Uncommon in healthy hearts. Occur in CCF, digoxin toxicity, IHD and AMI (esp. inferior)
No specific treatment. Treat underlying disorder
68. Junctional arrhythmias –
Junctional rhythm
Typically sinus node overdrive suppresses all other pacemakers
If sinus node discharge is <60 or is blocked, junctional escape beats can occur
Rate 40-60
Typically do not conduct retrogradely to the atria, so typically get QRS complex without P waves either before or
after
Accelerated junctional rhythms can occur at 60-100 or junctional tachycardia >100. Typically this will capture both
atria and ventricles.
Seen with digoxin toxicity, acute rheumatic fever, or inferior MI
Typically seen in sinus bradycardia, slow phase of sinus arrhythmia, AV block or in the pause after premature beats
Sustained junctional escape rhythms seen in CCF, myocarditis, hypokalaemia and digoxin toxicity
Treatment
If sustained, treat underlying cause, consider atropine
Consider potassium supplementation to high-normal
Consider digoxin toxicity and treatment thereof
69. Ventricular arrhythmias
- Premature ventricular contractions
ECG characteristics
P waves do not precede QRS
Retrograde P waves may be present
QRS is premature and wide
ST segment and T waves are directed opposite to the major QRS deflection
Usually don’t affect the sinus node so get a fully compensated post-ectopic pause (vs. PAC with uncompensated pause due to SA node reset)
May see fixed coupling interval (<0.04s) if single ectopic focus (with uniform or multiform PVC’s depending on ventricular depolarisation pattern)
May see fusion beats
Very common, even without structural heart disease
Occur in most patients with IHD and universally in AMI
Also seen in digoxin toxicity, CCF, hypokalaemia, alkalosis, hypoxia and sympathomimetic drugs
Unclear if these are an indicator of morbidity/mortality
Treatment
Treat underlying cause
If >3 in a row = non-sustained VT
No evidence that lignocaine therapy or oral antiarrhythmic therapy for chronic PVC’s has any mortality benefit
70. Ventricular arrhythmias – Ventricular
parasystole
Independent ectopic pacemaker (usually in ventricles) competes with dominant pacemaker
(entrance block)
Ectopic pacemaker has an innate rate so coupling interval is different each time
ECG characteristics
Variation in coupling interval
Common relationship between interectopic beat intervals
Fusion beats may be seen
Usually associated with severe IHD, AMI, hypertensive heart disease or electrolyte disturbance
Infrequently can lead to VT or VF
Treatment of underlying disease is crucial
Anti-arrhythmics indicated if symptomatic episodes or subsequent VT/VF
71. Ventricular arrhythmias – Accelerated
idioventricular rhythm (AIVR)
Ectopic rhythm of ventricular origin seen in reperfusion of AMI
ECG characteristics
Wide and regular QRS complexes
Rate 40-100
Runs of 3-30beats/min usually
Begins with fusion beat
Some association with VT (but not VF)
Usually causes no symptoms but loss of atrial kick may reduce CO
Treatment
Any suppression i.e. with lignocaine can cause asystole if this is the only pacemaker
Atrial pacing if reduced CO is problematic
72. Ventricular arrhythmias –
Ventricular tachycardia (VT)
3 or more sequential depolarisations from a ventricular pacemaker at >100/min
ECG characteristics
Wide QRS >0.10
Rate >100 (usually 150-200)
QRS axis usually constant
QRS <120ms in 5% of episodes
Monomorphic vs. polymorphic
Polymorphic – QRS complex of multiple morphologies in single lead
Torsade de pointes is a specific subtype of polymorphic VT in which QRS swings from positive
to negative axis in a single lead and QT is prolonged
Sustained vs. non-sustained vs. recurrent
Cannon a waves indicate AV dissociation
73. Ventricular arrhythmias –
Ventricular Tachycardia
Most common causes are IHD and AMI
Most common within 30 minutes of AMI (re-entrant mechanism)
Increased automaticity >12 hours after infarction
Less common causes include HOCM, mitral valve prolapse, drug toxicity (digoxin, quinidine, procainamide and sympathomimetics)
Hypoxia, alkalosis and electrolyte abnormalities
Cannot be differentiated from SVT by clinical criteria alone
Treat all wide complex tachycardia as VT until proven otherwise
Treatment
Unstable – Synchronised cardioversion 100-200J (90% effective)
90% successful if rate <200/min and 70% successful if rate >200 (opposite of SVT)
Stable
Amiodarone 150mg over 10 min, repeated up to 2g total then infusion
Procainamide
Lignocaine 1-1.5mg/kg IV every 5 min, repeated until effect
74. VT – Chemical cardioversion
Lignocaine
More effective in ischaemic VT due to depression of automaticity
Initial bolus 100mg (20% effective) and second bolus of 50mg effective in another 10%
Even less effective if not ischaemic
Sotalol
1.5mg/kg over 5 minutes
Only if haemodynamically stable and QTc normal
65% reversion rate
Amiodarone
150mg over 5-10 minutes (30% effective at 1 hour)
Second dose over 10-20 minutes if fails
600mg over next 24 hours
Adenosine
May treat unrecognised SVT with aberrancy and probably safe in VT
75. VT – Overdrive pacing
Set rate to 120% of current rate of VT
Start pacing by increasing current until electrical and mechanical capture achieved
After 20-30 seconds, gradually wind back rate to test if overdrive pacing has taken
over pacemaker function and terminated VT
Does not necessarily require sedation
Can precipitate VF
76. VT in special situations
Digitalis toxicity – Digibind
Chloral hydrate toxicity – Beta-blockade
Sodium channel blocker – Bicarb
Hypothermia – Active warming
Stimulants – Benzos, alpha and beta-blockers
Electrolyte imbalance – Replace/treat
77. VT – Fascicular tachycardia
Rare but may occur with structural heart disease
Usually misdiagnosed as SVT with RBBB
Key to diagnosis is recognition of VT features e.g. fusion/capture/AV dissociation
Usually originates in posterior fascicle
ECG features
Mimics SVT with aberrancy
Relatively narrow QRS 0.11-0.14
RBBB pattern
Usually left axis
Right axis deviation if from anterior fascicle
Rx
Verapamil
Does not respond to adenosine or standard anti-VT therapy
78. Right Ventricular Outflow Tract VT
Shows LBBB morphology with rightward axis
May be part of ARVD
Treated with adenosine +- IV verapamil
79. Ventricular arrhythmias
- Torsades de pointes
Typically short runs 5-15 seconds at 200-240/min
Seen in serious myocardial disease with prolonged QT
Risk factors for drug-induced TdeP
Age >65
Female
Renal impairment
Electrolyte disturbances
Arrhythmias with long pauses
Genetic predisposition
>1 drug administered known to cause prolonged QT
80. Ventricular arrhythmia - Torsades
Treatment
Cardioversion 200J if pulsless or in extremis
Magnesium 1-2g IV over 60-90s then infusion 1-2g/hr (rarely helpful if normal QT) =
10mmol bolus)
Withdraw offending agents
Correct electrolyte disturbances
Pacing if TdeP secondary to bradycardia or heart block (chemical or electrical)
81. Torsades de pointes vs. Polymorphic VT
Torsades specifically relates to a subtype of polymorphic VT associated with long
QT and is managed with magnesium
Polymorphic VT with normal QT duration is associated with myocardial ischaemia,
infarction or post-cardiac surgery should be managed as for monomorphic VT (and
not with magnesium)
QT prolongation
A risk for TdeP only if due to T wave prolongation (JT interval >380ms) NOT if due to
QRS prolongation
Risk increases 6% for every 10% increase in QTc above 500ms
82. VT vs. SVT with aberrancy
Age >35, IHD, CCF or CABG strongly suggest VT
Suggest VT
AV dissociation (seen in 10% of VT patients) and 75% specific for VT
Fusion beats (,10% of VT)
Capture beats (<10% of VT)
Josephson’s sign (notching near nadir of S wave)
Brugada’s sign (onset of QRS to nadir of S wave >0.1s) (2.5 squares)
Onset of R wave to deepest part of S wave >100ms is >95% specific for VT
QRS >0.14s
Post-ectopic fully compensatory pause
Constant coupling intervals
All positive or all negative deflections (20% sensitivity but 90% specificity)
Northwest (extreme) axis
Absence of typical RBBB or LBBB morphology (although 35% of ischaemic VT has LBBB morphology)
RSR= with taller left rabbit ear (vs. RBBB taller right rabbit ear - most specific)
83. VT vs. SVT with aberrancy
Suggest SVT with aberrancy
Preceding ectopic P wave
Varying BBB
Varying coupling intervals
Historical criteria
2 or more of the following = 95% probability of VT
Age >35
Active angina
Previous AMI
84. Brugada Method for VT vs. SVT with
aberrancy
VT diagnosed if, analysed in sequence, any of these 4 are present:
Absence of RS complexes in all praecordial leads
R to S interval >100ms in one or more praecordial leads
AV dissociation
V1: Monophasic R, qR, QS or RS + V6: rS, QS, qR or S > R
SVT diagnosed if none of above present
85. Griffith method
VT diagnosed if no to either criteria for SVT
SVT diagnosed if both criteria below present:
QRS morphology classic for BBB
LBBB
rS or QS in V1 and V2
Time to S wave nadir in V1 or V2 >70ms
R wave and no Q wave in V6
RBBB
rSR’ in V1
RS in V6
R wave > S wave in V6
No AV dissociation
86. Vereckai method
VT diagnosed if, analysed in sequence, any of the following 4 present in aVR
Initial R wave
Initial r or q wave >40ms
Notch on initial descending limb of predominantly negative QRS
Slow conduction at beginning of QRS
Ratio of vertical distance travelled in voltage during initial 40ms (Vi) and terminal 40 s (Vt)
Vi/Vt < 1 i.e. vertical amplitude of first 40ms in aVR less than the terminal 40s
87. Pava method
VT diagnosed if time from isoelectric line to peak of R wave in II > 50ms
Otherwise SVT
88. SVT with aberrancy
Aberrant wide complex QRS may be due to
Pre-existing BBB
Rate-related conduction block (common)
Ventricular pre-excitation syndrome (e.g. WPW)
Toxic-metabolic condition
Aberrancy defined as QRS >120ms
89. Ventricular arrhythmias - VF
May be primary or secondary to VT and prolonged LV failure/shock
Digoxin toxicity, quinidine toxicity, hypothermia, blunt chest trauma, severe electrolyte abnormality
or myocardial irritation by intracardiac catheter or pacemaker lead
Amplitude becomes less with time and becomes asystole within 1-3 minutes
3% of asystole is actually fine VF
Rate 300-600/min
Treatment
200J defibrillation (x3 if witnessed monitored)
Five cycles of CPR
Check pulse/rhythm
If ongoing VF, continue above + amiodarone 300mg IV bolus or lignocaine 1.5mg/kg IV
Consider beta-blocker if VF storm ??
90. VF
Special circumstances
Active cooling if <30
Bicarb if sodium channel blockade
K replacement if hypokalaemic
91. Electrical storm
Recurrent VT/VF despite conventional initial therapy
Treatment with additional antiarrhythmics may potentiate
Especially if prolonged QTc
Thought to be driven by sympathetic activity (so adrenaline questionable)
Defibrillate each episode
Correct K, Mg 10mmol
Beta-blockade may be beneficial
92. Conduction Disturbances
- Sinoatrial block aka exit block
First-degree SA block
Cannot be seen on ECG
Second-degree SA block
Some impulses get through, others do not
Suspect if expected P wave and QRS do not occur
Variable (Wenckebach-type)
Progressive shortening of P-P interval before dropped complex
Constant-type
Interval encompassing missed beat is an exact multiple of the cycle length
Third-degree SA block
May be due to sinus node failure, sinus node stimulus inadequate to activate atria or atrial
unresponsiveness
94. Conduction disturbances
- Sinus arrest
P-P interval bears no relationship to baseline sinus node discharge rate
Same conditions that cause sinus block can cause sinus arrest
If prolonged, can see AV junctional escape beats
Especially common in digoxin toxicity and aging, as in sick sinus syndrome
Treatment
Atropine if symptomatic
Cardiac pacing for symptomatic bradycardia
95. Conduction disturbances
- AV block
First-degree: No treatment necessary
Second-degree:
Type 1 Wenckebach
Symptomatic: atropine 0.5mg IV q5min or transcutaneous pacing
Type 2
Implies structural damage, permanency and may progress to complete heart block (especially in AMI)
If symptomatic: Transcutaneous pacer pads applied and atropine provided (60% effective)
Third-degree
Nodal blocks seen in 8% of inferior MI
Infranodal blocks wit broad complex escape rhythms may be seen in large anterior infarcts
Usually symptomatic
Treatment: Transcutaneous pacing. Atropine may be effective for nodal escape rhythms
96. First-degree AV block
PR >200ms
Av node is usually level of block but can be at an infranodal level
Occasionally seen in normal hearts
Commo causes include increased vagal tone, medication toxicity, inferior MI and
myocarditis
If no evidence of other cardiac disease, has no prognostic value
In the setting of inferior MI, may herald complete heart block
Close monitoring is all that is required if in setting of ischaemia
97. Second-degree (Type 1) Wenckebach AV
block
Progressive prolongation
4:3 ratio indicates 3 of 4 atrial impulses are conducted to the ventricles
Can have fixed ratio like this or can be variable
This block almost always occurs at level of AV node
Often due to reversible depression of the AV nodal conduction
Occurs as each successive depolarisation produces prolongation of the refractory period of the AV
node
As next atrial impulse comes along it meets the AV node earlier in its relative refractory period and
conduction occurs more slowly each time until atrial impulses reaches AV node in the absolute
refractory period
Usually transient and associated with inferior MI, medication toxicity, myocarditis or after cardiac
surgery
May be physiological in rapid atrial rates
If very slow or unstable, atropine will be effective in most
98. Second-degree Type 2 AV block
PR interval remains constant both before and after nonconducted atrial beats
Usually occurs in infranodal system, often with coexistant BBB or fascicular blocks
(therefore often wide QRS)
Even if QRS complex is narrow, the block is usually infranodal
High-grade if more than one consecutive P wave is not conducted
If 2:1 cannot differentiate between type 1 and type 2
If wide complex, typically infranodal
If narrow complex, 50:50 infranodal/AV nodal site of block
Consider worst-case and assume type 2 block in this situation
Treatment – Pacing pads, close monitoring. Atropine usually not helpful as infranodal in
most cases
99. Third-degree AV block
If occurs at AV node level, junctional escape rhythm at 40-60 occurs with narrow
QRS as originates above bifurcation of Bundle of His
If at infranodal level, get wide ventricular escape rhythm at <40/min
May be narrow if from His bundle or may be wide if bundle branch or Purkinje system
pacemaker
Nodal complete heart block occurs in 8% of inferior MI and may last for days
Infranodal AV block with wide QRS suggests structural damage to infranodal
system as seen with extensive anterior MI
If in context of ischaemia, mortality is increased even with pacing as suggests
extensive infarct
100. Conduction disturbances
Unifascicular blocks
No treatment required. Treat underlying cause if known
Bifascicular blocks
Generally no treatment required. Treat underlying cause if known
Placement of ventricular demand pacemaker indicated if symptomatic bradycardia
If AMI with pre-existing or new bi- or trifascicular block, prophylactic ventricular demand
pacemaker insertion is indicated
Trifascicular blocks
Placement of ventricular demand pacemaker indicated if symptomatic bradycardia
If AMI with pre-existing or new bi- or trifascicular block, prophylactic ventricular demand
pacemaker insertion is indicated
101. Brugada syndrome
Eight different genetic mutations lead to channelopathy in transmembrane sodium, calcium or potassium
ion channels
Highest incidence in Southeast Asians
Responsible for up to 60% of idiopathic VF
Clinical features
Majority asymptomatic and only found via incidental ECG
50% of patients with Brugada pattern suffer malignant arrhythmia
2-year death rate for missed diagnosis from ED is 30%
Average age at presentation is 30yo
Symptomatic patients may present with palpitations, near to complete syncope, or seizures due to VT
Characteristic ECG changes are not always present
Fever and provocative testing with flecainide may provoke ECG abnormalities associated with Brugada syndrome
102. Brugada syndrome
Need Brugada pattern + at least one of:
Syncopal episode
VF
Polymorphic VT
SCD in relative <45yo
ST segment elevation in family member
103. Brugada syndrome in leads V1-3
Type 1:
Coved-shaped ST elevation >2mm followed by inverted T wave
Type 2:
ST elevation >2mm
Trough in ST segment at least 1mm deep
Positive or biphasic T wave (Saddleback)
Type 3:
Coved-shaped or saddleback pattern ST segment with 1-2mm elevation only
104. Brugada syndrome
Type 1 considered diagnostic if appropriate clinical or family history
Type 2 and 3 suggestive but not diagnostic
Require further evaluation
In those with aborted sudden cardiac death, risk of recurrent VF is 50% within 5 years
Tall R wave in aVR due to delayed conduction in RVOT associated with higher risk of
arrhythmia
Treatment
Must recognise
Avoid sodium channel blockers and treat fever
ICD is the only proven therapy to terminate malignant ventricular dysrhythmias and prevent sudden
death
Quinidine can be helpful to reduce the incidence of dysrhythmias as adjunct to ICD
105. Long QT syndrome
13 variants of congenital long QT syndrome
1/2000 live births
QTc >440ms in males or >460ms in females
Risk of dysrhythmias increases with QTc
Moderate risk QTc 480-499ms
High risk QTc >500ms
Syncope is the most common symptom and torsades the most common dysrhythmia
Avoid channel blockers, impair cardiac repolarisation, prolong the QT or provoke tachydysrhythmias
Beta-blockers are initial treatment of choice (propranolol and nadolol are first-line)
Exercise is a trigger where swimming is notably dangerous
106. Arrhythmogenic RV dysplasia
Autosomal dominant inheritance
More common in males
Usually symptomatic at 15-40yo
Fibrosis of subendocardial areas of myocardium with RV dilation and hypokinesis
Aneurysms in inferior/apical/infundibular walls
Signs of RVH may be present
ECG
Anterior TWI or widened QRS V1-3
Right axis deviation may be present
Epsilon waves (25% of cases only)
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puter software or hardware.
By submitting or posting content on the weblog, you grant the Principal author, team and any company substantially under the control of the Principal author, the right to remove any content or comment that, in Principal author’s sole judgment, does not com-
ply with the terms and conditions of this Agreement or is otherwise objectionable. You also grant the Principal author and any company substantially under the control of Principal author the right to modify, adapt, and edit any content.
109. Disclaimer
DISCLAIMER REGARDING THIRD PARTY LINKS
The weblog may, from time to time, contain links to other (“third party”) web sites. These links are provided solely as a convenience and not as a guarantee or recommendation by the Principal author for the services, infor-
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If you decide to access a linked website, you do so at your own risk. Your use of other websites is subject to the terms of use for such sites.
The Principal author is not responsible for the content of any linked or otherwise connected web sites. The Principal author does not make any representations or guarantees regarding the privacy practices of, or the content
or accuracy of materials included in, any linked or third party websites. The inclusion of third party advertisements on the weblog does not constitute an endorsement, guarantee, or recommendation. The Principal
author makes no representations and/or guarantees regarding any product or service contained therein.
DISCLAIMER OF ALL WARRANTIES
Content made available at the weblog is provided on an “as is” and “as available” basis without warranties of any kind, either express or implied. Under no circumstances, as a result of your use of the weblog, will the Principal
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wise, even if advised of the possibility of such damages.
AGE RESTRICTION
The Site is intended for persons eighteen (18) years or older. Persons under the age of eighteen (18) should not access, use and/or browse the Site.
INDEMNIFICATION
You agree to indemnify and hold the Author harmless from any claim or demand, including attorneys’ fees, made by any third party as a result of (1) any content posted or made available by you on this weblog, (2) any viola-
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MODIFICATION
The Author may modify the terms and conditions of this Agreement in whole or in party at any time for any reason without any notice to you, based on her discretion. Such modified terms and conditions shall supersede
these terms and conditions and shall become binding when published online on the Site.
ENTIRE AGREEMENT
You accept that this Agreement represents the entire understanding between you and the Author concerning use of the Site.