Case Report

cardiac memory T-wave changes after ventricular tachycardia in pregnancy

Abstract

A 36-year-old pregnant woman (20 weeks) was admitted to the coronary care unit because of Ventricular tachycardia . 12-Lead electrocardiogram showed a monomorphic regular wide QRS tachycardia with a ventricular rate of 220 beats/min and Left bundle branch block morphology. Her electrocardiogram after the termi- nation of the tachycardia returned to baseline with the T- wave inversions in V1-V6 and DII, DII, aVF. The marked T-wave inversions demonstrate cardiac memory due to the preceding abnormal ventricular activation caused by VT. Because the T-wave inversion happened after the conver- sion from VT to sinus rhythm, it may be explained by the cardiac memory phenomenon.

A 36-year-old pregnant woman (20 weeks) was admitted to the coronary care unit (CCU) because of VT. On arrival to the CCU, the patient was not in acute distress. Blood pressure was 140/92 mm Hg, heart rate was

220 beats/min and regular, and respiratory rate was 20 breaths per minute. Her height was 160 cm and her weight was 90 kg. Cardiac examination revealed a regular tachycardia with normal S₁ and S₂; no S₃, S₄, or murmur was detected, and the lungs were clear to auscultation. Complete blood count, electrolytes (including calcium and magnesium), creatine kinase, and troponin I were all within normal limits. A 12-lead electrocardiogram showed a monomorphic regular wide QRS tachycardia with a ventricular rate of 220 beats/min and left bundle branch block morphology (Fig. 1).

Valsalva maneuver and carotid sinus massage had no effect on the tachycardia. Within 20 minutes of CCU arrival, the patient had 3 episodes of nonsustained VT. The patient received synchronized shocks at energy levels of 100 J with normal sinus rhythm. Lidocaine was started to suppress the monomorphic regular wide QRS tachycardia episodes (bolus 100 mg intravenously). Her ECG after the termination of the

tachycardia returned to baseline with the T-wave inversions in V1-V6 and DII, DII, aVF. QT was 320 msec in sinus rhythm (Fig. 2).The following day, a transthoracic echocar- diogram showed normal left ventricular size; ejection fraction was 65%. Careful examination of the right ventricle did not reveal any dysplasia. Cardiac catheterization could not be performed because of her pregnancy.

The ECG showed sinus rhythm with T-wave inversions, seen with slower rates with normal QRS duration, particu- larly in the precordial leads. The marked T-wave inversions seen in Fig. 2 demonstrate cardiac memory due to the preceding abnormal ventricular activation caused by VT. Because the T-wave inversion happened after the conversion from VT to sinus rhythm, it may be explained by the cardiac memory phenomenon [1,2].

In summary, cardiac memory is recognized as altered T waves when sinus rhythm resumes after a period of abnormal myocardial activation. Ventricular pacing or arrhythmias that frequently induce CM is associated with upright T waves in lead I and aVL, with narrow QRS morphology in contrast to the typically inverted T waves during ischemia in these leads.

M. Murat Sucu MD Vedat Davutoglu MD

Medical Faculty, Department of Cardiology

Gaziantep University Gaziantep, Turkey

doi:10.1016/j.ajem.2008.02.011

References

1. Rosenbaum MB, Blanco HH, Elizari MV, Lazzari JO, Davidenko JM. Electrotonic modulation of the T wave and cardiac memory. Am J Cardiol 1982;50:213-22.
2. Zoghi M, Nalbantgil S. Electrical stunning and hibernation: suggestion of new terms for short- and long-term cardiac memory. Europace 2004;6:418-24.

0735-6757/$ – see front matter (C) 2008

968.e2 Case Report

Fig. 1 12-Lead ECG showed a monomorphic regular wide QRS tachycardia with a ventricular rate of 220 beats/min and left bundle branch block morphology.

Case Report 968.e3

Fig. 2 Note the T-wave inversions, which demonstrate cardiac memory due to the preceding abnormal ventricular activation caused by VT.