Sinus Tachycardia – physiologic response to a stressor
Stressors include: hypoxia, hypovolemia, fever, anxiety, pain, hyperthyroidism, and exercise.
Certain drugs, such as stimulants (eg, nicotine, caffeine), medications (eg, atropine,
salbutamol), recreational drugs (eg, cocaine, amphetamines, ecstasy), and hydralazine, can also
induce the condition
Rx; address the underlying stressor
Atrial flutter – “sawtooth” pattern
Rx – tachycardia algorithm
If the patient is hypotensive or unstable, immediate cardioversion with sedation must be performed.
If the patient is stable, vagal maneuvers can be used to slow the heart rate and to convert to sinus rhythm.
If vagal maneuvers are not successful, adenosine can be used in increasing doses.
If adenosine does not work, atrioventricular (AV) nodal blocking agents like calcium channel blockers or
beta-blockers should be used, as most patients who present with PSVT have AV nodal reentrant tachycardia
(AVNRT) or AV reentrant tachycardia (AVRT). These arrhythmias depend on AV nodal conduction and therefore
can be terminated by transiently blocking this conduction
Since atrial fibrillation and atrial flutter increase risk of stroke or cerebrovascular accidents, anticoagulation is
Atrial fibrillation - chaotic atrial depolarization
Treatment goals include the following:
1.Conversion to normal sinus rhythm
2.Keeping the patient in normal sinus rhythm
3.Control of ventricular rate
4.Preventing thromboembolic disease
Beta-blockers and calcium channel blockers are first-line agents for rate control in AF. These
drugs can be administered either intravenously or orally.
Patients with newly diagnosed AF and patients awaiting electrical cardioversion can be started on
intravenous heparin (activated partial thromboplastin time [aPTT] of 45-60 seconds) or low-
molecular-weight heparin (1 mg/kg bid).
AVNRT - AVNRT occurs when a reentrant circuit is present within the AV node itself. In this
situation, there are two separate conduction pathways within the AV node instead of just one
(present in about 5% of the general population).
This is sometimes termed “dual AV nodal physiology”. One pathway is slower and has a short
refractory period while the other is faster and has a long refractory period. Normal conduction
occurs through the faster pathway with the long refractory period.
If a premature atrial contraction (PAC) or less commonly a premature ventricular contraction
(PVC) occurs at the right time, the normal conduction pathway will still be refractory, so the
action potential will conduct through the fast AV nodal pathway with the shorter refractory
period instead. After this action potential reaches the ventricles or atrium, it will conduct back
through the normal AV nodal conduction pathway since it will no longer be refractory and a
reentrant circuit will be created.
Rx - VT associated with loss of consciousness or hypotension is a medical emergency
necessitating immediate cardioversion. In a normal-sized adult, this is typically accomplished
with a 100- to 200-J biphasic cardioversion shock administered according to standard Advanced
Cardiovascular Life Support (ACLS) protocols
Pulseless VT, in contrast to other unstable VT rhythms, is treated with immediate
Shock administration should be followed by immediate chest compressions, airway
management with supplemental oxygen, and vascular access with administration of
Electrical external defibrillation remains the most successful treatment of ventricular fibrillation (VF).
A shock is delivered to the heart to uniformly and simultaneously depolarize a critical mass of the
excitable myocardium. The objective is to interfere with all reentrant arrhythmia and to allow any
intrinsic cardiac pacemakers to assume the role of primary pacemaker
AHA algorithm (refer previous slide)
Lack of response to standard defibrillation algorithms is challenging.
After initial amiodarone bolus, consider continued amiodarone therapy with 1 mg/min IV for 6
hours, then 0.5 mg/min for 18 hours.
If ongoing ischemia is the suspected cause of recurrent VF, consider emergent cardiac catheterization
and possible angioplasty even in the absence of STEMI, and intra-aortic balloon pump placement.
For patients with prolonged and refractory inhospital cardiogenic arrest that included VF/VT, it has
been shown that extracorporeal cardiopulmonary resuscitation was associated with improved
neurologically intact survival.This study was performed in a large tertiary center with an ongoing
protocol for this advanced experimental care.
Rx – depends on the cause ( refer algorithm)
Intravenous access, supplemental oxygen, and cardiac monitoring should be initiated
In symptomatic patients, intravenous atropine may be used.
In rare cases, transcutaneous pacing may need to be initiated.
All patients should be receiving advanced life support (ACLS) with continuous cardiac
monitoring, as per local protocols. In all patients, oxygen should be administered and
intravenous (IV) access established. Maneuvers likely to increase vagal tone (eg, Valsalva
maneuvers, painful stimuli) should be avoided. Atropine can be administered but should be
The first, and sometimes most important, medical treatment for heart block is the withdrawal
of any potentially aggravating or causative medications. Many antihypertensive, antianginal,
antiarrhythmic, and heart failure medications cause AV block that resolves after withdrawal of
the offending agent.
Review patient medication lists upon presentation to help rule out medication-induced or
medication-aggravated heart block. Common drugs that induce AV block include beta-blockers,
calcium channel blockers, antiarrhythmics, and digoxin.
Intravenous access, supplemental oxygen, pulse oximetry
Immediate administration of aspirin en route
Nitroglycerin for active chest pain, given sublingually or by spray
If STEMI is present, the decision as to whether the patient will be treated with thrombolysis or
primary PCI should be made within the next 10 minutes. Treatment options include the
immediate start of IV thrombolysis in the ED or the immediate transfer of the patient to the
cardiac catheterization laboratory for primary percutaneous transluminal coronary angioplasty
The AHA recommends the initiation of beta-blockers to all patients with STEMI (unless beta-
blockers are contraindicated)