The similarity of changes in segmental contraction patterns induced by postextrasystolic potentiation and nitroglycerin.

Abstract

SUMMARY Despite a fundamental difference in their underlying mechanisms, both postextrasystolic potentiation (PESP) and administration of nitroglycerin (TNG) have been utilized to predict reversibility of abnormal segmental wall motion in patients with ischemic heart disease. To determine whether these interventions induce the same changes in segmental contraction pattern, we analyzed biplane ventriculograms of 14 patients who had an adequately visualized PESP beat on a basal ventriculogram as well as a post-TNG ventriculogram. Four segments in each plane were defined and the area ejection fraction of each segment was calculated for a basal sinus, PESP, and post-TNG beat. To correct for global differences in the response to PESP and TNG, we normalized each segmental ejection fraction (NSEF) by the ventricular ejection fraction for that beat and IN PATIENTS WITH ISCHEMIC HEART DISEASE, localized segments of the ventricle which display decreased systolic wall motion may be composed of compromised but viable muscle fibers rather than scar tissue.",2 With the development of coronary artery bypass surgery, the concept of restoring contractile function by improving blood supply to an ischemic area has received increased consideration and has been supported by documentation of improvement in left ventricular function in some patients after such surgery.2 To preoperatively identify ischemic regions of the ventricle with the potential to improve their contractile function after adequate revascularization, several groups of investigators have evaluated the response of abnormally contracting segments to postextrasystolic potentiation (PESP), which enhances myocardial contractility, or to administration of nitroglycerin (TNG), which usually decreases the workload of the heart. Both of these interventions have been reported to improve the systolic motion of some hypokinetic and akinetic segments,'-"' and limited postoperative studies appear to confirm the predictive value of these induced changes.88.10 The use of PESP requires a ventriculogram with an early extrasystole followed by an adequately visualized sinus beat, whereas the administration of TNG requires the performance of a second ventriculogram. In an individual patient, the choice of which intervention to use may be limited. Therefore, we performed this study to ascertain whether the comparative effects of PESP and TNG are the same for all segments of a given ventricle regardless of the basal function of any segment and despite the difference in the underlying mechanisms of the two interventions. MethodsIn patients with chest pain suggestive of angina, we performed retrograde left heart catheterization with the patient in the postabsorptive state and following premedication with diazepam, 10 mg i.m. A #7F NIH catheter was passed from the right brachial artery or a #8F pigtail catheter was passed from the right femoral artery. Left ventricular pressures were monitored using a Statham P23Db

Evaluation of left ventricular residual function using postextrasystolic potentiation. Relation between systolic time intervals and angiographic study.

“…The reason for these differences is unknown, but may be explained by a difference in responsiveness to PESP by the diseased left ventricle. The amount of decrease in PEP/ET and increase in the EF with PESP was greater in our patients with severe ventricular dysfunction, and this finding is in agreement with previously noted observations.6),13) The postextrasystolic changes in the ESV, SV and EF were significant, and this result is consistent with those of other investigators.1),13), 26) The PEP/ET ratio versus the EF: The PEP/ET ratio is considered to be a clinically useful index for prediction of cardiac function,5) and there is a good correlation of PEP/ET with the cardiac output, SV4) and EF7),24) in patients with coronary artery disease and diffuse cardiomyopathy.…”

Effects of nitroglycerin on echocardiographic measurements of left ventricular wall thickness and regional myocardial performance during acute coronary ischemia.

“…We arbitrarily measured echocardiographic wall thickness to the nearest 0.5 mm, approximately 6% of control enddiastolic wall thickness, while some of the techniques used in animals evidently will resolve length differences as small as 0.05 mm.2 In the present study we could detect significant differences in end-diastolic 11,[13][14][15] with nitroglycerin administration. Differences between improved systolic shortening and unimproved systolic thickening in the acute experimental preparations might be explained by speculating that the former measurements could be affected by compressive forces from surrounding normal myocardium, and the latter might not be.…”

Comparison between the effect of postextrasystolic potentiation and the effect of nitrates on left ventricular function for the differentiation between reversible and irreversible left ventricular asynergy

“…There is controversy concerning the efficacy of nitrates and the PES potentiation for this differentiation: Banka et al (2) and KIausner et al (9) assume that both interventions have similar effects on asynergic areas, whereas Schwarz et al (5) suppose that the potentiation by the PES beat seems to be superior to the effect of nitrates. In the present study, therefore, the effect of both nitrates and PES potentiation were investigated in the same patient.…”