A brief history focused on whether the patient has heart disease can be revealing. Ventricular arrhythmias predominate in patients with known structural heart disease as well in as older adults with other risk factors for heart disease. Supraventricular arrhythmias tend to be more common in younger, healthier patients and in those in whom arrhythmias may have preceded their development of heart disease. In a study of conscious patients who presented with a wide-QRS-complex tachycardia, an affirmative answer to two questions addressing these issues (“Have you ever had a heart attack in the past?” and “Did [these kind of symptoms] start after your heart attack?”) correctly identified VT as the culprit arrhythmia in nearly all (28 of 29) cases.¹ Comparison of a prior ECG (if available) with an ECG of the current arrhythmia can also be quite helpful.

The physical examination of patients in arrhythmia should initially assess for signs of hemodynamic instability or evidence that the arrhythmia is being poorly tolerated, including level of consciousness, heart rate, and blood pressure, followed by evidence of heightened sympathetic drive, including skin pallor, cool extremities, and diaphoresis. Auscultation of lung fields may reveal diffuse crackles suggestive of pulmonary edema. The pulse may be regular, irregularly irregular, thready, or absent. Variability in the intensity of the first heart sound (S1) and cannon “A” waves in the jugular pulse are highly sensitive and specific indications of atrioventricular dissociation associated VT. Although these signs are helpful when detected, very often the rapid ventricular rate precludes making a rhythm diagnosis on the basis of physical findings alone. Documenting the rhythm through rhythm monitoring or an electrocardiogram (ECG) is required.

ECG monitoring should be instituted as soon as possible, ideally simultaneous with the initial assessment of the patient. In emergent or semiemergent circumstances, this can be done most efficiently by applying defibrillation electrodes (from which the ECG can be monitored) or by use of the “quick-look paddles” feature available on most conventional defibrillators. Early ECG monitoring is also important in high-risk patients, such as those with acute myocardial infarction (AMI) or severe ischemia. Because the greatest risk for serious arrhythmias exists during the first hour after onset of symptoms of infarction or ischemia, health care professionals should start cardiac monitoring as soon as possible.

All ECG and rhythm information should be interpreted in context of other available information about the patient, including ventilation, oxygenation, heart rate, blood pressure, level of consciousness, acid-base status, and medication use. In specific clinical settings, care providers should consider possible aggravation of arrhythmias by antiarrhythmic drugs (proarrhythmia), adverse drug effects from intentional or unintentional overdose, or drug toxicity occurring with normal dosing patterns or as a result of drug-drug interactions.

With these principles in mind, care providers should:

Providers of acute cardial life support (ACLS) should also participate in training and evaluation sessions that will establish their ability to detect and treat serious arrhythmias, including regular updates to enhance their expertise in rhythm interpretation and in using and troubleshooting ECG monitoring equipment.