Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

first-degree AV block or type I second-degree AV block

1st line – monitoring

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ACUTE
|
first-degree AV block or type I second-degree AV block
|
asymptomatic
1st line – 

monitoring

Patients are at low risk for progression to higher-degree AV block. ECGs may be re-checked if symptoms develop, but do not need to be re-checked on a routine basis.

1st line – discontinuation of AV-nodal blocking medications

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ACUTE
|
first-degree AV block or type I second-degree AV block
|
symptomatic
1st line – 

discontinuation of AV-nodal blocking medications

Patients with first-degree AV block and a PR interval >0.30 seconds (or >300 milliseconds) may experience symptoms related to the haemodynamic consequence of such prolonged AV delay. An increased pulmonary capillary wedge pressure and attendant symptoms of dyspnoea result, as well as decreased ventricular filling leading to decreased stroke volume and cardiac output. This constellation of symptoms is similar to the pacemaker syndrome experienced by some pacemaker patients. Some patients with type I second-degree AV block can experience symptoms, ranging from those related to first-degree AV block to more generalised symptoms of fatigue, pre-syncope, or syncope.

The most common AV-nodal blocking medications include beta-blockers, non-dihydropyridine calcium-channel blockers, and digitalis.

Risks and balances of discontinuing possible causative medications (e.g., beta-blockers) should be weighed in each instance.

2nd line – infrequently: PPM or cardiac resynchronisation therapy ± ICD placement

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ACUTE
|
first-degree AV block or type I second-degree AV block
|
symptomatic
2nd line – 

infrequently: PPM or cardiac resynchronisation therapy ± ICD placement

If symptoms are severe enough, permanent pacemaker (PPM) implantation should be considered. For AV block, usually a dual-chamber (1 right atrial and 1 right ventricular lead) pacemaker is placed. The procedure includes a 2-inch incision at the non-dominant shoulder, placement of the leads through the subclavian vein, and placement of the pulse generator in a small subcutaneous pocket. The entire procedure usually takes a few hours and requires an overnight hospital stay.

Biventricular pacemaker (placement of a third wire, in a branch of the coronary sinus, to enable left ventricular pacing), with or without an implantable cardioverter-defibrillator (ICD) placement, may be considered when the left ventricular ejection fraction is ≤35%.[36][37][38] (An ICD is not indicated for patients with New York Heart Association [NYHA] Class IV heart failure symptoms: severe limitation of exercise capacity due to shortness of breath with symptoms even while at rest; these are mostly bedbound patients.)

type II second-degree AV block or third-degree AV block

1st line – condition-specific management and discontinuation of AV node-blocking drugs

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ACUTE
|
type II second-degree AV block or third-degree AV block
|
asymptomatic or mildly to moderately symptomatic
1st line – 

condition-specific management and discontinuation of AV node-blocking drugs

Mild to moderate symptoms include fatigue or dyspnoea, especially exertional, mild symptoms of CHF (pedal oedema, orthopnoea), or mild, episodic lightheadedness.

The most common AV-nodal blocking medications include beta-blockers, non-dihydropyridine calcium-channel blockers, and digitalis. While discontinuing these medicines may improve AV conduction, they are not likely to completely reverse clinically significant AV block.

Condition-specific management includes treating acute coronary syndrome (i.e., anti-platelet medications, urgent revascularisation) and medication toxicity (e.g., glucagon for beta-blocker toxicity, calcium for calcium-channel toxicity, or digoxin antibody for digitalis toxicity). When present, electrolyte or pH disturbances and hypoxaemia should be treated appropriately.

Risks and balances of discontinuing possible causative medications (e.g., beta-blockers) should be weighed in each instance.

Primary options

digitalis toxicity

digoxin immune Fab: consult specialist for guidance on dose

OR

beta-blocker toxicity

glucagon: consult specialist for guidance on dose

OR

calcium-channel blocker toxicity

calcium chloride: consult specialist for guidance on dose

2nd line – PPM or cardiac resynchronisation therapy ± ICD placement

Back
ACUTE
|
type II second-degree AV block or third-degree AV block
|
asymptomatic or mildly to moderately symptomatic
2nd line – 

PPM or cardiac resynchronisation therapy ± ICD placement

Patients with type II second-degree AV block or third-degree AV block are at risk for progression to slower ventricular rates and development or worsening of symptoms.[39] In the absence of a reversible cause, these patients should undergo permanent pacemaker (PPM) implantation.[Figure caption and citation for the preceding image starts]: Patient with 2:1 AV block, status post permanent pacemaker placementCourtesy of Dr Susan F. Kim, Dr John F. Beshai, and Dr Stephen L. Archer; used with permission [Citation ends].com.bmj.content.model.Caption@7eb15fd3

For AV block, usually a dual-chamber (1 right atrial and 1 right ventricular lead) pacemaker is placed. The procedure includes a 2-inch incision at the non-dominant shoulder, placement of the leads through the subclavian vein, and placement of the pulse generator in a small subcutaneous pocket. The entire procedure usually takes a few hours and requires an overnight hospital stay.

Biventricular pacemaker (placement of a third wire, in a branch of the coronary sinus, to enable left ventricular pacing), with or without an implantable cardioverter-defibrillator (ICD) placement, may be considered when the left ventricular ejection fraction (LVEF) is ≤35%.[36][37][38]​ (An ICD is not indicated for patients with New York Heart Association [NYHA] Class IV heart failure symptoms: severe limitation of exercise capacity due to shortness of breath with symptoms even while at rest; these are mostly bedbound patients.) In patients with high-degree or complete heart block and LVEF of 36% to 50%, CRT may reduce total mortality and hospitalisations, and improve symptoms and QOL.[40]

1st line – condition-specific management, discontinuation of AV-nodal blocking drugs, and temporary (transcutaneous or transvenous) pacing

Back
ACUTE
|
type II second-degree AV block or third-degree AV block
|
severely symptomatic
1st line – 

condition-specific management, discontinuation of AV-nodal blocking drugs, and temporary (transcutaneous or transvenous) pacing

Severe symptoms include syncope or persistent, severe lightheadedness indicating profound decreases in the ventricular rate.

When the ventricular rate is significantly low (<40 to 45 bpm) or the blood pressure is low (mean arterial pressure <65 mmHg), temporary (transcutaneous or transvenous) pacing should be considered. Transvenous pacing is much more reliable than transcutaneous pacing and should be performed by a cardiologist when the heart block leads to haemodynamic instability.

Condition-specific management includes treating acute coronary syndrome (i.e., antiplatelet medications, urgent revascularisation) and medication toxicity (e.g., glucagon for beta-blocker toxicity, calcium for calcium-channel toxicity, or digoxin antibody for digitalis toxicity). When present, electrolyte or pH disturbances and hypoxaemia should be treated appropriately.

Risks and balances of discontinuing possible causative medications (e.g., beta-blockers) should be weighed in each instance.

Primary options

digitalis toxicity

digoxin immune Fab: consult specialist for guidance on dose

OR

beta-blocker toxicity

glucagon: consult specialist for guidance on dose

OR

calcium-channel blocker toxicity

calcium chloride: consult specialist for guidance on dose

2nd line – PPM or cardiac resynchronisation therapy ± ICD placement

Back
ACUTE
|
type II second-degree AV block or third-degree AV block
|
severely symptomatic
2nd line – 

PPM or cardiac resynchronisation therapy ± ICD placement

Severe symptoms include syncope or persistent, severe lightheadedness indicating profound decreases in the ventricular rate.

Permanent pacemaker (PPM) implantation is required if the cause of AV block is irreversible. [Figure caption and citation for the preceding image starts]: Patient with 2:1 AV block, status post permanent pacemaker placementCourtesy of Dr Susan F. Kim, Dr John F. Beshai, and Dr Stephen L. Archer; used with permission [Citation ends].com.bmj.content.model.Caption@7096f736 For AV block, usually a dual-chamber (1 right atrial and 1 right ventricular lead) pacemaker is placed. The procedure includes a 2-inch incision at the non-dominant shoulder, placement of the leads through the subclavian vein, and placement of the pulse generator in a small subcutaneous pocket. The entire procedure usually takes a few hours and requires an overnight hospital stay.

Biventricular pacemaker (placement of a third wire, in a branch of the coronary sinus, to enable left ventricular pacing), with or without an implantable cardioverter-defibrillator (ICD) placement, may be considered when the left ventricular ejection fraction is ≤35%.[36][37][38]​ (An ICD is not indicated for patients with New York Heart Association [NYHA] Class IV heart failure symptoms: severe limitation of exercise capacity due to shortness of breath with symptoms even while at rest; these are mostly bedbound patients.) In patients with high-degree or complete heart block and LVEF of 36% to 50%, CRT may reduce total mortality and hospitalisations, and improve symptoms and QOL.[40]​

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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