The heart remembers.

Abstract

Time for primary review 21 days. Cardiac memory was characterized by Rosenbaum et al. in 1982 as ST-T wave changes induced by ventricular pacing or arrhythmia that persist long after normal ventricular activation has resumed [1]. Rosenbaum's work enlarged upon the earlier studies of Chatterjee et al. [2]who reported persistent postpacing changes in T wave morphology. The key aspects of cardiac memory were that the magnitude and persistence of the postpacing T wave changes increased with the duration of abnormal ventricular activation (referred to as ‘accumulation’) (Fig. 1), and the subsequent normalization of the T wave occurred slowly, requiring hours to months, depending on the duration of the inciting stimuli. Fig. 1 (A) T wave changes in a human subject in complete heart block before and after siting a ventricular pacemaker, and then with the pacemaker turned off after 15 minutes and 3, 8 and 15 days after the onset of pacing. Note the progressive evolution of the T wave change (reprinted from reference [2], by permission). (B) Cardiac memory evolution over 21 days of ventricular pacing (VP). Depicted are leads I and aVR from one dog during control, during VP, and at the end of 1 hour after pacing was discontinued on days 7, 14, and 21. In both leads, evolution of the T wave is such that it tracks the vector of the paced QRS complex (reprinted from reference [15], by permission). (C) Frontal plane vectorcardiographic depiction of cardiac memory from the same dog presented in Figure 1B. A shows P, QRS, and T wave vectors in control, before the onset of pacing. B: The QRS and T vectors during ventricular pacing. C: The T wave vector alone (note enlarged scale as well as dotted line indicating the change in vector) during sinus rhythm in control … * Corresponding author. Tel.: +1-212-305-8754; fax: +1-212-305-8351; e-mail: emf3@columbia.edu