BRADYCARDIA

Bradycardia (a heart rate below 60 beats/min) is not infrequently found during a routine physical examination. Visualizing the conduction system of the heart recalls the sick sinus syndrome, atrioventricular (A-V) nodal rhythm, or A-V block, but, unfortunately, it does not help recall the many causes of these disorders. The mnemonic VINDICATE is the most useful aid in my experience.

1. V—Vascular diseases suggest myocardial infarction, especially inferior wall and anteroseptal infarctions. Arteriosclerosis may also cause focal ischemia of the conducting system.
2. I—Inflammatory disease suggests viral myocarditis, diphtheria, and Chagas disease.
3. N—Neurologic disorders, because neoplasms of the heart are infrequent. Neurologic disorders include vasovagal syncope (common faint), cerebral concussion, and anything else that might cause an increased intracranial pressure (e.g., subarachnoid hemorrhage and cerebral tumor).
4. D—Degenerative and deficiency diseases suggest beriberi and myocardial fibroelastosis.
5. I—Intoxication suggests alcoholic myocardiopathy, digitalis, propranolol (Inderal), procainamide, and quinidine toxicity or effects, as well as other cardiac drugs. The hypokalemia of chlorothiazide diuretics and the hyperkalemia of uremia, triamterene (Dyrenium), and spironolactone also are suggested.
6. C—Congenital disorders that might cause bradycardia include many congenital heart diseases, sickle cell anemia, glycogen storage disease, and muscular dystrophy.
7. A—Autoimmune disorders constitute a large group of diseases that may cause bradycardia or heart block. Sarcoidosis, amyloidosis, lupus erythematosus, and rheumatic fever are some of the most important ones.
8. T—Trauma is not a significant cause; however, a stab wound could sever the conduction system.
9. E—Endocrine disorders include myxedema and endocrine disorders that cause electrolyte disturbance such as Addison disease (hyperkalemia), aldosteronism (hypokalemia), and hyperparathyroidism (hypercalcemia).

BRADYCARDIA

Approach to the Diagnosis

The finding of bradycardia in an otherwise healthy adult is probably normal. Nevertheless, other symptoms and signs should be looked for. Fever suggests meningitis, yellow fever, or a cerebral abscess. A history of syncope requires that sinus arrest or complete heart block be ruled out. If a heart murmur is present, aortic stenosis must be considered. If there is nonpitting edema and brittle hair and nails, myxedema should be ruled out. If there is a history of chest pain, perhaps the patient has had a recent myocardial infarction. It is important to find out what medications the patient is taking. ϐ-Blockers, digitalis, quinidine, and various cholinergic drugs may induce bradycardia.

The initial workup should include a CBC, urinalysis, thyroid profile, sedimentation rate, chemistry panel, ECG, and chest x-ray. If there is fever, febrile agglutinins and a survey for other infections should be made. If there is nuchal rigidity, a spinal tap should be done, preferably after a CT scan. If a myocardial infarction is suspected, serial cardiac enzymes and ECGs should be done. If valvular heart disease is suspected, echocardiography should be done. If there is a history of syncope, the patient needs 24- to 48-hour Holter monitoring. When this is unrevealing, a continuous-loop event recording may be conducted over a 1- to 2-week period.

Other Useful Tests

1. Exercise stress testing (heart block, coronary insufficiency)
2. His bundle study (heart block)
3. Serum digitalis level
4. VDRL test (cardiac syphilis)
5. ANA analysis (collagen disease)
6. Coronary angiogram (myocardial infarction, coronary insufficiency)
7. Angiocardiogram (valvular heart disease)

Book Source Details

• Book Title: Differential Diagnosis in Primary Care
• Author(s): R. Douglas Collins
• Year of Publication: 2007
• Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: Differential Diagnosis in Primary Care Authors: R. Douglas Collins Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-7817-6812-8

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