cardiac dysrhythmias and their management basic

1. CARDIAC
DYSRHYTHMIAS
SUDESHNA BANERJEE
M.SC (N) 2ND YEAR
HFCON

2. ATRIOVENRICULAR JUNCTIONAL
DYSRHYTHMIAS
 Junctional rhythm describes an abnormal heart rhythm
resulting from impulses coming from a locus of tissue in the
area of the atrio-ventricular node; the "junction" between
atria and ventricles
 If the SA node fails to fire & an impulse is not initiated in
other ectopic sites in the atria, the AV junction is the next
pacemaker for the heart

4. Cont…
During junctional rhythms, cardiac output decreases because
there is no atrial kick to the ventricles
 2 major types of dysrhythmias arise in the AV junction:
• Disturbances in automaticity, with the AV junctional tissue
assuming the role of the pacemaker
• Disturbances in conduction, with the AV junction blocking
impulses journeying from the atria to the ventricles
In this case, the PR interval shortens to less than 0.12
second

5. Disturbances in automaticity
Premature Junctional Contractions:
Also called atrio-ventricular junctional premature
complexes or junctional extra systole
A PJC is the single, early firing of a junctional ectopic
focus
Clients are usually asymptomatic & no interventions
required

7. Paroxysmal Junctional Tachycardia
• A junctional rhythm with a rate that exceeds 60 beats/min
is called a junctional tachycardia
• Usually stops and starts abruptly
• Rate is between 140-220 beats/min
 Causes may be metabolic imbalances, increased
sympathetic stimulation, Digitalis toxicity, Acute coronary
syndrome

8. Disturbances in impulse conduction
 FIRST DEGREE ATRIO-VENTRICULAR BLOCK: a delay in passage
of the impulse from atria to ventricles creating a prolonged P-R
interval is greater than normal 0.20 seconds
 The rhythm is regular and each P wave is followed by a QRS
complex & the P-R interval usually remain constant
(this characteristic is an important differentiation between AV
blocks)
 Causes: Atrial septal defect, right atrial enlargement

10.  SECOND DEGREE ATRIOVENTRICULAR BLOCK:
Some impulses are conducted and others are blocked
Results in intermittently dropped QRS complex
Atrial depolarization continues producing normal appearing P
waves at regular intervals
Causes: CAD, rheumatic fever, viral infections, inferior wall MI
Can be divided into 2 additional types:
Mobitz type1 & mobitz type2

11. Type 1 (Mobitz I/Wenckebach)
An abnormally long refractory period at the AV node, this
delay causes the P-R interval to progressively lengthen until
the P wave fails to conduct to the ventricles & a QRS
complex is dropped
As the P-R interval lengthens, the R-R interval becomes
shorter
Carries a better prognosis compared to type II

13. Type 2 (Mobitz II/Hay)
Occurs when a P wave is not conducted, resulting in a
dropped QRS complex
Here P-R interval remains constant without prolongation
P waves are normal and are followed by normal QRS
complexes at regular intervals until suddenly a QRS
complex is dropped
Causes: ischaemia, MI, drug toxicity, congenital valvular
heart disease, hyperkalemia

14. Third degree atrio-ventricular block
Also known as complete heart block, is a condition in which
the impulse generated in the sinoatrial node (SA node) in
the atrium of the heart does not propagate to
the ventricles
Sometimes called a AV dissociation because upper & lower
chambers on the heart are working independently
Ventricular rate is typically 40-60 beats/mins

17. Cont…
Causes:
MI
Congenital anomalies
Myocarditis
Trauma
Cardiomyopathy
Lyme disease

18. Intraventricular impulse conduction
abnormalities
Bundle-branch block: Indicates that conduction is impaired
in one of the bundle branches (distal to bundle of his) &
thus the ventricles don’t depolarize simultaneously
Abnormal conduction causes a wide (greater than 0.20 sec)
or notched QRS complex
Causes: MI, CAD, cardiomyopathy, myocardial fibrosis,
pulmonary embolism

19. Cont…
Bundle branch block can be of 2 types.
Left bundle branch block:
The QRS complex in V1 is described as rS or QS
Carries a worse prognosis
Composed of anterior and posterior fascicles & one or
both fascicles may be involved
No specific intervention

21. Right bundle branch block:
• The QRS complex is described as rsR
• Exists along with block in one of the fascicles of the
left bundle, the one remaining fascicle represents
the only conduction pathway to the ventricles
• A pacemaker is required

23. VENTRICULAR ARRHYTHMIAS
Disturbances in automaticity:
Premature Ventricular Complexes (PVCs): Originate from an
irritable focus in the ventricular conduction system or muscle
tissue.

25. Cont…
Causes:
 Myocardial hypoxia
 Hypokalemia
 Hypocalcemia
 Acidosis
 Heart failure
 Intracardiac catheters

26. Ventricular fibrillation
Most serious cardiac rhythm disturbance. The lower
chambers quiver and the heart can't pump any blood,
causing cardiac arrest
The heart's lower chambers contract in a rapid,
unsynchronized way. (The ventricles "fibrillate" rather than
beat.) The heart pumps little or no blood
 Causes: Cardiomyopathy, Problems with the aorta, Drug
toxicity, Sepsis

28. Long Q-T syndrome
Produces episodic tachydysrhythmias including torsades de
pointes, which may eventually lead to ventricular fibrillation

29. Pre-excitation syndromes
 Accessory connections between the atrium and ventricle
are the result of anomalous embryonic development of
myocardial tissue bridging the fibrous tissues that separate
the two chambers.
 The tissue allows for electrical conduction between atria
and ventricles at sites other than the atrio-ventricular node

30. Wolf Parkinson White Syndrome (WPW):
WPW is caused by the presence of an abnormal accessory
electrical conduction pathway between the atria and
the ventricles
Electrical Signals through abnormal pathway stimulate the
ventricles to contract prematurely
A unique type of supraventricular tachycardia referred to as
an ”atrioventricular reciprocating tachycardia”

31. Disturbances in conduction
Ventricular asystole:
 Ventricular asystole or cardiac standstill represents the total
absence of ventricular electrical activity
 The client has no palpable pulse and a rhythm is absent if the
client is monitored
 Ventricular systole can occur as a primary event, or it may
follow VF or pulseless electrical activity
 Asystole can also occur in patients with complete heart block
in whom there is no escape without pacemaker

33. Cont…
Causes:
 Hypoxia
 Hyperkalemia & hypokalemia
 Pre-existing acidosis
 Drug overdose
 Hypothermia

34. Pulseless electrical activity
 A clinical condition characterized by unresponsiveness and lack
of palpable pulse in the presence of organized cardiac electrical
activity
 Pulseless electrical activity has previously been referred to as
electromechanical dissociation (EMD)
 The absence of peripheral pulses should not be equated with
PEA, as it may be due to severe peripheral vascular disease

36. Sudden cardiac death
 Defined as death resulting from abrupt loss of heart
function(cardiac arrest)
 The time & mode of death are unexpected, and death
occurs within minutes after the manifestations appear
 More than 163,000 deaths occur annually because of
sudden cardiac death

37. MANAGEMENT OF DYSRHYTHMIAS
PHARMACOTHERAPY:
Sodium Channel Blockers
• Procainamide
• Quinidine
• Disopyramide
 Effects on cardiac activity
Decrease automaticity

38. CONT…
 Uses:
• Acute : Ventricular tachycardia and fibrillation
(esp. during ischemia)
• Not used in atrial arrhythmias or AV junctional
arrhythmias

39. BETA-ADRENOCEPTOR-BLOCKING DRUGS
• Propranolol
• Acebutolol
• Esmolol
Cardiac effects:
• Increase APD and refractory period in AV node to
slow AV conduction velocity

40. Cont…
 Uses:
Treating sinus and catecholamine dependent tachy-
arrhythmias
Converting re-entrant arrhythmias in AV
Protecting the ventricles from high atrial rates (slow
AV conduction)

41. ANTI-ARRHYTHMIC AGENTS
• Amiodarone
• Sotalol
• Ibutilide
• Dofetilide
Cardiac effects:
• Increase refractory period and  APD (K+)
• Decrease conduction (Na+)
• Decrease speed of AV conduction
 Uses: Very wide spectrum: effective for most arrhythmias

42. CALCIUM CHANNEL-BLOCKING DRUGS
• Verapamil
• Diltiazem
Cardiac effects:
• Slow conduction through AV (Ca++)
• Increase refractory period in AV node
 Uses:
• Control ventricles during supraventricular tachycardia
• Convert supraventricular tachycardia (re-entry around AV)

43. DEFIBRILLATION
• Defibrillation is a treatment for life-threatening cardiac
dysrhythmias, specifically ventricular fibrillation (VF)
and non-perfusing ventricular tachycardia (VT)
• Electrical intervention can:
 Abruptly stop the heart’s erratic electrical discharge
 Restore the flow of electrical current where there is none

44. CONT…
Defibrillation is a process in which an electrical device
called a defibrillator sends an electric shock to the heart to
stop an arrhythmia resulting in the return of a productive
heart rhythm.
This current causes the entire myocardium to
depolarize completely at the moment of shock.

45. Indication
• Defibrillation is indicated only in certain types of cardiac
dysrhythmias, specifically ventricular fibrillation (VF) and pulseless
ventricular tachycardia
Contraindication
• If the heart has completely stopped, as in asystole or pulseless
electrical activity (PEA), defibrillation is not indicated
• Defibrillation is also not indicated if the patient is conscious or has a
pulse. Improperly given electrical shocks can cause dangerous
dysrhythmias, such as ventricular fibrillation

46. PROCEDURE
Defibrillators deliver a brief electric shock to the heart, which enables the heart's
natural pacemaker to regain control and establish a productive heart rhythm
The defibrillator is an electronic device that includes defibrillator paddles and
electrocardiogram monitoring
During external defibrillation, the paddles are placed on the patient's chest with a
conducting gel ensuring good contact with the skin
When the heart can be visualized directly, during thoracic surgery, sterile internal
paddles are applied directly to the heart
Defibrillation continues until the patient's condition stabilizes or the
procedure is ordered to be discontinued.

48. Care before defibrillation:
If the client is not responsive, call for immediate assistance
Call for the defibrillator and crash cart
Assess the client’s airway, breathing and circulation
Open airway: look, listen and feel
If the client is not breathing, give 2 slow breaths
Assess the client’s circulation, if no pulse present, start CPR
Perform CPR until defibrillator in place
Check ECG to verify the presence of VF or pulseless VT
Remove any nitroglycerin patch

49. Care after defibrillation:
After defibrillation, the patient's cardiac status, breathing, and
vital signs are monitored with a cardiac monitor
Additional tests to measure cardiac damage will be performed,
which can include a 12 lead electrocardiogram, a chest x-ray,
and cardiac catheterization
Treatment options will be determined from the outcome of
these procedures. The patient's skin is cleansed to remove gel
and, if necessary, electrical burns are treated

50. ABLATION CONDUCTION
Variety of procedures can be used when medications
are not successful in bringing about conversion of the
abnormal rhythm
Interventions include:
1. Chemical and mechanical ablation
2. Radiofrequency ablation of the abnormal
pathway

51. CHEMICAL ABLATION
Alcohol or phenol is inserted into the involved areas of the
myocardium through an angioplasty catheter leading to
myocardial necrosis
Alcohol septal ablation is a technique designed to reduce
the obstruction to blood being ejected from the heart. The
technique creates a small controlled heart attack, killing the
area of heart muscle responsible for the obstruction, and
eventually causing it to become less thick.

52. MECHANICAL ABLATION
The abnormal pathway is surgically removed or treated
with a cryoprobe to interrupt its effect on heart rhythms
SVT, atrial fibrillation, atrial flutter, WPW syndrome are
treated with this method
The procedure can be performed with open-heart or
closed-heart methods
Its purpose is to remove skin spots, aged skin, wrinkles,
thus rejuvenating it

53. CRYOPROBE

54. RADIOFREQUENCY ABLATION
RFA is used primarily for SVT associated with WPW or AV
nodal entry, also used to treat VT
Pacing catheter directs low-power, high frequency current
to a localized accessory pathway & necroses a small portion
of myocardium
The temperature of the contact tissue rises, water is driven
out, and coagulation necrosis results

55. Cont…
The amount of tissue injury depends on the amount
of energy delivered (5 to 50 W), the length of time
it is delivered(10-90 secs)
Major advantage of RFA is high rate of success,
especially with SVT, and low morbidity

57. SURGICAL MANAGEMENT
Automatic implantable cardioverter-defibrillator: The
automatic implantable cardioverter-defibrillator (AICD) is a
device designed to monitor the heartbeat.
 This device can deliver an electrical impulse or shock to the
heart when it senses a life threatening change in the
heart’s rhythm. Like a pacemaker, the AICD is small enough
to be implanted under the skin in the upper chest.

59. The AICD system consists of:
A pulse generator that can send an electrical impulse or
shock to the heart
Electrodes that sense the rhythm of the heart and deliver a
shock to the heart muscle
Batteries designed to last 4 to 5 years and deliver about
100 shocks
A small computer chip that tells the AICD when to deliver a
shock

60. Uses
The indications for an AICD are:
People whose heart suddenly stops
People who have had documented excessive rapid
heartbeats (ventricular tachycardia)
Or patients who are at risk for the above rhythm problems
due to: A poor or inadequate blood flow to the heart, A
severe heart attack (MI), An enlarged heart
(cardiomyopathy) or related conditions like congestive
heart failure

61. Pacemakers
• A pacemaker (or artificial pacemaker) is a medical device which uses
electrical impulses, delivered by electrodes contracting the heart
muscles, to regulate the beating of the heart
Types
Implantable pulse generators with endocardial or myocardial
electrodes for long-term or permanent use( permenant pacemakers)
External, miniaturized, transistorized, patient portable, battery-
powered, pulse generators with exteriorized electrodes for
temporary transvenous endocardial or transthoracic myocardial
pacing. (temporary pacemakers)

64. THE MACHINE:
Modern pacemakers have two parts. One part, called the pulse
generator, contains the battery and the electronics that control your
heartbeat. The other part is one or more leads to send electrical signals
to your heart. Leads are small wires that run from the pulse generator to
your heart. Pacemakers generally treat two types of arrhythmias:
tachycardia, a heartbeat that’s too fast, bradycardia, a heartbeat that’s
too slow.

65. INDICATIONS
• Sinus node dysfunction
• Acquired atrio-ventricular block in adults
• Chronic bifascicular block
• After acute myocardial infarction
• Hypersensitive carotid sinus syndrome and neuro-
cardiogenic syncope
• After cardiac transplantation
• Pacing to prevent tachycardia
• Patients with congenital heart disease

66. COMPLICATIONS
An allergic reaction to anesthesia
Bleeding
Bruising
Damaged nerves or blood vessels
An infection at the site of the incision
A collapsed lung, which is rare
A punctured heart, which is also rare

67. Client with permanent Pacemaker
should be taught:
Measure the pulse rate as instructed by the physician in
wrist or on neck
Notify physician if pulse rate is slower
Avoid being near areas with high voltage, magnetic force
fields, or radiation
Avoid being near large running motors(gas or electric) and
standing near high-tension wires, power plants, radio
transmitters, large industrial areas etc