History
Symptoms of paroxysmal tachycardia must be elicited. Manifestations of such paroxysms include palpitations, lightheadedness, and shortness of breath. In cases of underlying structural heart disease or coronary artery disease, episodes of tachycardia may induce cardiac stress and produce symptoms of chest pain or possibly of hypotension or other hemodynamic instability. At higher ventricular rates, syncope may occur, particularly if ventricular tachycardia or ventricular fibrillation are initiated.
Physical Examination
An accentuated first heart sound of mitral valve closure may be present in 87% of cases. [3] During paroxysms of tachycardia, cardiovascular examination may reveal a rapid heart rate. Absence of a rapid heart rate does not exclude LGL as a possible diagnosis, as the tachycardia of LGL is paroxysmal.
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ECG demonstrating a short PR interval of approximately 100 ms and normal QRS.
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ECG demonstrating ventricular preexcitation. A delta wave, which corresponds to initial myocardial depolarization via a bypass tract, appears at the beginning of each QRS complex.
