SLOW PULSE RATE

SALIENT FEATURES

History

· Drug history: beta-blockers, digoxin, verapamil.

· Is the patient an athlete'?

· Symptoms which are usually non-specific (e.g. dizziness, fatigue, weakness. heart failure).

· History of recent myocardial infarction.

· Ask if the bradycardia is episodic. If so, enquire about precipitating factors and associated symptoms

or signs.

· Ask about nocturnal bradycardia (a feature of obstructive sleep apnoea).

Examination

· Pulse rate of less than 60 beats per minute (N Engl J Med 2000; 342:703 9). · Pulse rate may be either

regular or irregular.

· If the pulse is irregular, get the patient to stand and then count his pulse rate (in complete heart

block there is no increase in rate).

· Look at the JVP for cannon 'a' waves.

· Auscultate the heart for cannon first heart sound.

· Look for signs of hypothyroidism, particularly in the elderly.

DIAGNOSIS

This patient has a complete heart block (lesion) probably due to ischaemic heart disease (aetiology) and

is disabled by syncopal attacks (functional status).

QUESTIONS

What are the causes of bradycardia?

· Physical fitness in athletes.

· Idiopathic degeneration (ageing).

· Acute myocardial infarction.

· Drugs (beta-blockers, digitalis, calcium channel blockers).

· Hypothyroidism.

· Obstructive jaundice.

· Increased intracranial pressure.

· Hypothermia.

· Hyperkalaemia.

ADVANCED-LEVEL QUESTIONS

How would you investigate this patient?

· 12-lead ECG to confirm bradycardia.

· 2448-hour ambulatory ECG recording is useful in patients with frequent or continuous symptoms.

· Exercise ECG or ambulatory monitoring for chronotropic incompetence.

· Tilt-table testing when neurocardiogenic syncope is suspected.

What are the indications for temporary cardiac pacing in bradyarrhythmias ?

· Symptomatic second- or third-degree heart block due to transient drug intoxication or electrolyte

disturbance.

· Complete heart block, Mobitz II or bifascicular block in the setting of an acute myocardial infarct.

· Symptomatic sinus bradycardia, atrial fibrillation with slow ventricular response.

What are the indications for permanent pacing in bradyarrhythmias?

· Symptomatic congenital heart block.

· Symptomatic sinus bradycardia.

· Symptomatic second- or third-degree heart block.

Which drug would you use to treat sinus bradycardia seen in the setting of an acute myocardial

infarction?

Intravenous atropine.

What do you understand by the term chronotropic incompetence?

Failure to reach a heart rate that is 85% of the age-predicted maximum (220 - age in years) at peak

exercise, the failure to achieve a heart rate of 100 beats per minute, or a maximal heart rate more than 2

SD below that in a control population (N Engl J Med 2000; 342:703 9).

What do you know about Stokes-Adams syndrome?

It refers to syncope or tits occurring during complete heart block.

W. Stokes (1804-1878), Regius Professor of Medicine in Dublin, graduated from Edinburgh.

R. Adams (1791-1875), Professor of Surgery in Dublin, was an authority on gout and arthritis.