T-wave Abnormalities on Preoperative Electrocardiogram Caused by “Cardiac Memory” Related to Intermittent Preexcitation (2024)

Anesthesiology September 2002, Vol. 97, 764–765.

To the Editor:—

T-wave inversions on the electrocardiogram attributed to abnormal ventricular repolarization may reflect the presence of ischemic heart disease. However, alteration in the ventricular depolarization pattern seen in intermittent left bundle branch block, ventricular pacing, or preexcitation can also cause abnormal ventricular repolarization (T-wave abnormalities on the electrocardiogram) persisting even after normalization of ventricular depolarization is restored. 1–4This curious phenomenon is termed “cardiac memory.” We present a patient with intermittent preexcitation in whom T-wave inversions on a preoperative electrocardiogram seen during the absence of δ waves could be explained by cardiac memory but not by myocardial infarction/ischemia.

A healthy 38-yr-old man (weight, 70 kg; height, 176 cm) was scheduled for left knee arthroscopy under spinal anesthesia. He had no remarkable past medical history. He did not smoke, and he was not taking any medications or excessive alcohol. A standard 12-lead electrocardiogram on admission showed T-wave inversions in the limb leads of II, III, and aVF, which could not exclude inferior myocardial infarction/ischemia (fig. 1A). However, he was completely asymptomatic, and he had never experienced chest pain. Laboratory data, including cardiac enzymes, was normal, and the chest radiograph was unremarkable. Transthoracic echocardiography was normal, without any regional wall motion abnormalities. An exercise stress test was not performed because of left knee pain. At the preoperative anesthetic interview, the patient reported that he had experienced a few episodes of palpitation that spontaneously dissipated within a few minutes. Therefore, we performed electrocardiographic monitoring at his bedside, which demonstrated intermittent preexcitation with obvious δ waves. We thought the T-wave inversions on the admission electrocardiogram might likely be caused by cardiac memory related to intermittent preexcitation. The next day, spinal anesthesia was administered with 0.5% hyperbaric bupivacaine (Marcain® spinal 0.5% hyperbaric; AstraZeneca, Osaka, Japan), 2.0 ml, at the L3–L4 interspace. The anesthetic course was uneventful. There were no episodes of paroxysmal supraventricular tachycardia, although δ waves appeared intermittently throughout the surgery.

A postoperative 12-lead electrocardiogram showed ventricular preexcitation with negative δ waves in leads II, III, and aVF, the leads where T-wave inversions had been observed most prominently (fig. 1B). These findings further support that the T-wave inversions on the admission electrocardiogram were caused by cardiac memory rather than by myocardial ischemia. No further cardiac investigations have been performed because of a lack of symptoms.

Normally, ventricular repolarization proceeds in a direction opposite to that of depolarization, resulting in the same polarity for the T wave as for the QRS complex. 3When cardiac memory is noted, the T-wave direction is typically similar to the direction of the QRS complex during the period of altered ventricular depolarization (e.g., left bundle branch block pattern) but not that of the QRS complex after normalization of ventricular depolarization, hence, the term “memory.”1In cardiac memory phenomena associated with preexcitation, the vector of T-wave changes occurring after loss of preexcitation is in the same direction as the previous δ-wave vector, and thus, T-wave inversions are most commonly observed in leads with negative δ waves. 3In this case, the preexcited electrocardiogram showed negative δ waves in leads II, III, aVF, and V1, which may indicate a right posteroseptal accessory pathway. The T-wave inversions were marked in leads II, III, and aVF.

We cannot be absolutely certain that the T-wave inversions were caused by cardiac memory related to intermittent preexcitation because no further investigations, including exercise stress test and/or coronary angiography, were performed to rule out the possibility of myocardial ischemia. However, in a healthy young patient with no cardiac risk factors or symptoms and a normal heart on echocardiography, as in our case, it is unlikely that myocardial ischemia-induced T-wave inversions occur.

In conclusion, we present a case suggesting cardiac memory, a curious electrophysiologic phenomenon that is unfamiliar to anesthesiologists. This phenomenon should also be considered if T-wave inversions are observed on the electrocardiogram before anesthesia.

References