Repetitive narrow QRS tachycardia in a 61 year old female patient with recent palpitations
A 61 year old female patient suffering from recent onset palpitations and dyspnea on exertion with hypertension and mitral valve prolapse in her past history came to our outpatient department. Echocardiography revealed a mild mitral valve prolapse, slightly decreased left ventricular (LV) function (LV ejection fraction: 51% and a mild mitral regurgitation. Initial 12 lead ECG showed normal sinus rhythm (NSR) with left anterior hemiblock, upper normal limit (105110 ms) QRS duration and left atrial abnormality (not shown) 24 hour ambulatory ECG monitoring (Figure 1) revealed a great variety of narrow QRS complex arrhythmias at first glance looking like sinus beats alternating either with aberrantly conducted atrial premature beats with hidden low amplitude P waves (Figure 1 first three rhythm strips) or with ventricular premature beats (Figure 1 upper rhythm strip) arranged in a bigeminal pattern. The third rhythm strip of Figure 1 may also be considered a narrow QRS complex tachycardia with alternating shorter and longer cycle lengths (CL) and the fourth rhythm strip of Figure 1 is a completely regular narrow QRS complex tachycardia with alternating narrow QRS complexes of slightly different morphology. These non sustained narrow QRS tachycardias occurred repetitively separated by 1 or 2 sinus beats. After the 24 hour ECG monitoring another 12 lead ECG was recorded (Figure 2) which showed short, repetitive narrow QRS complex supraventricular tachycardia (SVT) runs separated by two sinus beats. The QRS morphology was identical to that of the initial 12 lead ECG. After a closer look at the ECG demonstrated in Figure 2, the most striking feature of the repetitive narrow QRS complex arrhythmias is that there are distinct, regular sinus P waves throughout the whole ECG tracing with a normal sinus rate of 7886 beats/min and the number of P waves
Journal of geriatric cardiology JGC