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INTRODUCTION

Tachyarrhythmias may appear in the presence or absence of structural heart disease; they are more serious in the former. Conditions that provoke arrhythmias include (1) myocardial ischemia, (2) heart failure, (3) hypoxemia, (4) hypercapnia, (5) hypotension, (6) electrolyte disturbances (e.g., hypokalemia and/or hypomagnesemia), (7) drug toxicity (digoxin, pharmacologic agents that prolong the QT interval), (8) caffeine consumption, (9) ethanol consumption.

Diagnosis

Examine ECG for evidence of ischemic changes (Chap. 120), prolonged or shortened QT interval, characteristics of Wolff-Parkinson-White (WPW) syndrome (see below), or ST elevation in leads V1–V3 typical of Brugada syndrome. See Fig. 132-1 and Table 132-1 for diagnosis of tachyarrhythmias; always identify atrial activity and relationship between P waves and QRS complexes. To aid the diagnosis:

TABLE 132-1CLINICAL AND ELECTROCARDIOGRAPHIC FEATURES OF COMMON ARRHYTHMIAS

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