Effects of enhanced external counterpulsation on hemodynamics and its mechanism.

BACKGROUND: The hemodynamic effects of enhanced external counterpulsation (EECP) and its mechanism(s) were investigated in relation to neurohumoral factors in patients with acute myocardial infarction (AMI). METHODS AND RESULTS: Twenty-four patients with AMI were studied before, during and after EECP treatment for 60 min. Heart rate (HR), right atrial pressure (RAP), pulmonary capillary wedge pressure (PCWP) and cardiac index (CI) were determined. In addition, circulating concentrations of neurohumoral factors were determined at each time point. HR did not change following EECP treatment. However, RAP and PCWP increased significantly and CI was significantly elevated during EECP and thereafter. Blood atrial natriuretic peptide (ANP) concentration was significantly increased 15 and 60 min after the start of EECP treatment, but brain natriuretic peptide (BNP) did not change. Renin, aldosterone and catecholamine concentrations also did not change. CONCLUSION: Treatment with EECP resulted in an increased preload because of increased venous return, and CI was increased thereafter. In patients with AMI, EECP increased blood ANP concentration, but not BNP, which suggests that an increase in ANP without an increase in BNP is an important mechanism for the effects of EECP treatment.

Administration of atrial natriuretic peptide attenuates reperfusion phenomena and preserves left ventricular regional wall motion after direct coronary angioplasty for acute myocardial infarction.

To evaluate the effects of synthetic human atrial natriuretic peptide (hANP) on myocardial reperfusion injury and left ventricular remodeling, 19 patients within 12 h of a first attack of anterior myocardial infarction (AMI) underwent intracoronary injection of 25 microg of hANP immediately after coronary angioplasty, combined with intravenous infusion of 0.025 microg x kg(-1) x min(-1) of hANP initiated on admission for 1 week (hANP group); 18 similar patients had saline administered (control group). The incidences of premature ventricular contraction, ventricular tachycardia and/or fibrillation in the hANP group were significantly less than in the control group after coronary angioplasty. Left ventricular ejection fraction was significantly greater and left ventricular end-diastolic volume index was significantly smaller 6 months after coronary angioplasty. Left ventricular regional wall motion of the infarcted segments significantly increased. Thus, hANP remarkably suppressed reperfusion phenomena and preserved left ventricular function through improvement of regional wall motion of the infarcted segments after coronary angioplasty.