Detection of Residual Myocardial Function in Coronary Artery Disease Using Post-extra Systolic Potentiation

Abstract

Improved global or segmental wall motion following revascularization suggests potential reversibility of ischemic left ventricular dysfunction in coronary artery disease (CAD). This study evaluates the effectiveness of post-extra systolic potentiation (PESP) to detect latent residual contractile function. Quantitative left ventriculography was performed in 15 patients with CAD (including seven with significant asynergy) and in three normal controls. During the ventriculogram, a single extra-systole was introduced by an R-wave coupled stimulator (R-stimulus interval averaged 398 msec, with an average mA of 2.4). PESP improved segmental axis shortening in 51 of 55 normal axes and 15 of 17 hypokinetic or akinetic axes. It also increased both ejection fraction and mean rate of circumferential fiber shortening in 17 of 18 patients. No significant arrhythmia occurred with this technique. A single interposed beat with PESP in one ventriculogram is a safe, effective method to detect residual potential contractile function in myocardium that may be hypokinetic or akinetic under conditions of the study.

Medical and Cellular Implications of Stunning, Hibernation, and Preconditioning

“…107,108 In l974, in studies at Brigham and Women's Hospital, Horn et al 109 pointed out that in patients with coronary artery disease and chronic asynergy, epinephrine infusion improved impaired regional wall motion. Postextrasystolic potentiation 110 after coronary artery bypass grafting in the absence of transmural necrosis. The concept of hibernating myocardium [113][114][115] has stimulated extensive clinical and basic investigation.…”

Detection of latent function in acutely ischemic myocardium in the dog: comparison of pharmacologic inotropic stimulation and postextrasystolic potentiation.

“…Preliminary data indicate that PESP can also improve ventricular performance and enhance segmental function in patients with coronary artery disease (17). Furthermore, the initial observations in man have revealed that the extrasystole must be introduced later in the electrical cycle (after the T wave) to obtain depolarization and PESP (17).…”

“…Furthermore, the initial observations in man have revealed that the extrasystole must be introduced later in the electrical cycle (after the T wave) to obtain depolarization and PESP (17). Even though repetitive firing has occurred with stimuli introduced at nearly all parts of the electrical cycle in the dog (18), the initiation of ventricular tachycardia or fibrillation was not encountered in 15 patients with coronary artery disease (17).…”

“…Furthermore, the initial observations in man have revealed that the extrasystole must be introduced later in the electrical cycle (after the T wave) to obtain depolarization and PESP (17). Even though repetitive firing has occurred with stimuli introduced at nearly all parts of the electrical cycle in the dog (18), the initiation of ventricular tachycardia or fibrillation was not encountered in 15 patients with coronary artery disease (17). Thus, although the vulnerable period is close to the peak of the T wave and, in ischemic muscle, becomes wider with the threshold for ventricular tachycardia and fibrillation decreasing due to both ischemia (19) and the extrasystole (20), this theoretical consideration does not appear to be a major limiting factor in clinical use of this technique.…”

Relation between contractile reserve and prognosis in patients with coronary artery disease and a depressed ejection fraction.

“…The techniques and protocols involved in both methods have been previously described in detail." 2 Briefly, the epinephrine ventriculogram was performed in 14 subjects approximately 30 min after the control ventriculogram, and 9 min after a [1][2][3][4] ,ug/min infusion of l-epinephrine had begun. Ejection March 1975 for introducing ventricular premature contractions when this device is not available: 1) by pulling a catheter back through the right ventricle into the right atrium, and 2) as a result of the power injection of angiographic contrast medium into the left ventricle.…”