CARDIAC ARRHYTHMIAS
With few exceptions, the etiologies of cardiac arrhythmias like those
of bradycardia can best be recalled using the mnemonic VINDICATE. The
exceptions are from one pathophysiologic cause: obstruction and
consequent dilatation of one or more of the chambers of the heart. Thus,
mitral stenosis with obstruction and dilatation of the left atrium is a
prominent cause of atrial arrhythmias, especially of auricular fibrillation.
Hypertension and aortic stenosis may cause a number of atrial and
ventricular arrhythmias. Pulmonary hypertension resulting from pulmonary
emphysema, fibrosis, or pneumonia with consequent right ventricular and
atrial obstruction, and dilatation cause arrhythmias, especially atrial
arrhythmias. Getting back to VINDICATE completes the recall of the
causes of arrhythmias.
V—Vascular diseases include myocardial infarction, coronary
insufficiency, and coronary artery emboli.
I—Inflammatory diseases include viral myocarditis, diphtheria,
syphilis, tuberculosis, and Chagas disease.
N—Neoplasms include atrial myxomas, but the N also stands for
neuropsychiatric causes. Paroxysmal atrial tachycardia is especially likely
to result from emotional causes.
D—Degenerative diseases include Friedreich ataxia, myotonic
dystrophy, myocardial fibroelastosis, and other myocardopathies.
I—Intoxication suggests the largest number of causes of arrhythmia:
Alcohol, caffeine, tobacco, digitalis, quinidine, propranolol, and
procainamide are just a few. Diuretics cause electrolyte disturbances that
may cause or contribute to cardiac arrhythmias.
C—Congenital disorders recall congenital heart diseases, many of
which cause recurrent arrhythmias. The Wolff–Parkinson–White syndrome
predisposes to atrial tachycardia. Muscular dystrophy may cause
myocardiopathy and arrhythmias. Von Gierke disease and gargoylism also need
to be remembered.
A—Autoimmune disorders suggest the arrhythmias of amyloidosis,
sarcoidosis, scleroderma, periarteritis nodosa, and rheumatic fever.
T—Trauma suggests the arrhythmias in shock, burns, stab wounds to
the heart, and head injuries. Electric shock is a cause of ventricular
fibrillation.
E—Endocrinopathies should remind one of hyperthyroidism, a prominent
cause of atrial fibrillation, Addison disease, and aldosteronism, which
disturb the electrolytes sufficiently to cause arrhythmias.
Pheochromocytomas may cause atrial tachycardia from the tremendous output of
epinephrine.
Approach to the Diagnosis
The diagnosis depends a lot on the type of arrhythmia. Atrial premature
contractions are usually benign, and an extensive workup is unnecessary
unless other physical signs indicate the need for it. Infrequent ventricular
premature contractions (VPCs) in otherwise healthy individuals probably can
be handled the same way. When VPCs are frequent or multifocal, an exercise
tolerance test, echocardiogram, and perhaps coronary angiography are
indicated. Runs of ventricular tachycardia require an extensive workup,
including coronary angiography, but usually there will be other signs to
indicate the need for this.
Atrial tachycardia and fibrillation require a workup of hyperthyroidism and
pulmonary disease, systemic hypertension, and congestive heart failure
(CHF). Atrial obstruction and dilatation should be excluded by
echocardiography.
Any arrhythmia warrants an electrocardiogram (ECG) and
possibly repeated ECGs. The Holter monitor should be used if there is doubt
about the type of arrhythmia.
Other Useful Tests
-
Complete blood count (CBC) (anemia)
-
Thyroid
profile
(hyperthyroidism,
hypothyroidism)
-
Urinalysis (renal disease)
-
Chemistry panel (uremia, electrolyte imbalance)
-
Sedimentation rate (infection)
-
Serial cardiac enzymes (myocardial infarction)
-
Serum and urine osmolality (CHF)
-
Exercise tolerance test (coronary insufficiency)
-
Serial ECGs (myocardial infarction)
-
Signal-averaging ECG and electrophysiologic testing (localize site
of irritable focus)
-
Pulmonary function tests (CHF, emphysema)
-
Echocardiogram (CHF, valvular heart disease)
-
Coronary angiogram (coronary insufficiency)
-
Drug screen (chronic drug abuse)
-
Hold all drugs (drug intoxication)
Pictures
Book Source Details
- Book Title: Differential Diagnosis in Primary Care
- Author(s): R. Douglas Collins MD, FACP
- Year of Publication: 2007
- Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.
Other Book Chapters Related to Heart symptoms
Read excerpts from these other book chapters related to Heart symptoms:
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Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.
More About Causes of Heart symptoms
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