Improvement in exercise-induced left ventricular dysfunction by infusion of alpha-human atrial natriuretic peptide in coronary artery disease

Alpha-human atrial natriuretic peptide, carperitide, reduces infarct size but not arrhythmias after coronary occlusion/reperfusion in dogs

Carperitide, a recombinant form of alpha-hANP, possesses potent diuretic, natriuretic, and vasodilatory activity, and inhibits the renin-aldosterone system and sympathetic nervous activity. However, its beneficial effects on ischemic myocardium have not been studied fully. We examined carperitide's effects on infarct size, hemodynamics, and arrhythmia frequency in anesthetized dogs (n = 20) subjected to a 90-min coronary artery occlusion/6-h reperfusion protocol. Intravenous infusion of carperitide (0.2 microg/kg/min) commenced 15 min after occlusion and continued during occlusion/reperfusion. Ventricular fibrillation developed in two of 10 control versus three of 10 treated dogs (p = NS). Hemodynamics, collateral blood flow to the ischemic wall measured 10 min after occlusion, and extent of area at risk were comparable for the two groups. Infarct size/area at risk was smaller in treated than in control dogs (4.5 +/- 2.1% vs. 27.8 +/- 7.8%, respectively; p < 0.05). During occlusion, carperitide tended to increase collateral blood flow (+39%) and significantly decreased left ventricular systolic pressure (-13%) and end-diastolic pressure (-40%) compared with baseline. In control dogs, collateral blood flow tended to decrease (-8.3%), whereas most hemodynamic parameters did not change significantly with respect to baseline. The number of arrhythmias recorded during occlusion/reperfusion was similar in the two groups. Intravenous administration of carperitide limited infarct size, but did not reduce incidence of ventricular arrhythmias after 90-min coronary occlusion/6-h reperfusion in anesthetized dogs. Although the beneficial effects of carperitide may be attributable to concomitant changes in hemodynamics and collateral blood flow, the precise mechanisms require further investigation.

Atrial natriuretic peptide attenuates pacing-induced myocardial ischemia during general anesthesia in patients with coronary artery disease

Atrial natriuretic peptide (ANP) exerts a dilatory effect on coronary arteries in humans. We investigated the effects of ANP on pacing-induced myocardial ischemia during enflurane anesthesia in patients with coronary artery disease (CAD). In 20 patients with CAD, myocardial ischemia was induced by atrial pacing before and after an i.v. infusion of ANP (50 mg x kg(-1) min(-1), n = 10) or placebo (n = 10). We studied the effects of ANP or placebo on pacing-induced changes in central hemodynamics, myocardial blood flow and regional myocardial indices of lactate uptake (RMLU), and oxygen consumption (RMVO2) and extraction (RMO2E). ST-segment depression was less pronounced during pacing with ANP compared with control pacing (-0.09 +/- 0.01 vs -0.24 +/- 0.02 mV; P < 0.001). RMLU decreased to -11.1 micromol/min during control pacing compared with -0.7 micromol/min during pacing with ANP (P < 0.01). ANP did not affect pacing-induced changes in RMVO2, RMO2E, or the rate pressure product. Placebo did not affect pacing-induced changes in ST-segment depression or RMLU. In conclusion, ANP attenuates ischemic ST-segment depression and lactate release during pacing-induced myocardial ischemia in patients with CAD. The antiischemic effect of ANP was not accompanied by any improvement in the regional myocardial oxygen supply/demand relationship.

IMPLICATIONS

We evaluated the effects of i.v. atrial natriuretic peptide (50 ng x kg(-1) x min(-1)) on pacing-induced myocardial ischemia during general anesthesia in patients with coronary artery disease. In contrast to placebo, atrial natriuretic peptide attenuated ST-segment depression and myocardial lactate production and improved left ventricular function during pacing-induced ischemia.

Natriuretic peptides: physiology, therapeutic potential, and risk stratification in ischemic heart disease

BACKGROUND

The natriuretic peptide family consists of four molecules that share significant amino acid sequence homologic characteristics and a looped motif. Atrial natriuretic peptide and brain natriuretic peptide are similar in their ability to promote natriuresis and diuresis, inhibit the renin-angiotensin-aldosterone axis, and act as vasodilators. Understanding of the actions of C-type natriuretic peptide and dendroaspis natriuretic peptide is incomplete, but these two new family members also act as vasodilators. Because of the rapid evolution of information about this peptide family, we reviewed the state of the art with respect to risk stratification and therapeutic ability.

METHODS

English-language papers were identified by a MEDLINE database search covering 1966 through 1997 and supplemented with bibliographic references and texts.

CONCLUSIONS

The natriuretic peptides are counterregulatory hormones with prognostically important levels. They are similarly upregulated in heart failure and counteract neurohormones that induce vasoconstriction and fluid retention. BNP may be the superior prognosticator for risk stratification after myocardial infarction and is independent of left ventricular ejection fraction. Lastly, experimental trials suggest that administration of exogenous natriuretic peptides or inhibitors of their catabolism to patients with ischemic heart disease may be clinically beneficial.

Myocardial circulatory and metabolic effects of atrial natriuretic peptide after coronary artery bypass grafting

The purpose of this study was to examine the effects of incremental infusion rates of human atrial natriuretic peptide (ANP), 25, 50, 100 ng.kg-1. min-1, on myocardial blood flow and metabolism (n = 10), and to compare the effects of ANP on these variables with those of equipotent infusion rates of sodium nitroprusside (SNP) (n = 9) 1-3 h after coronary artery bypass grafting (CABG). ANP induced a dose-dependent decrease in mean arterial blood pressure and systemic vascular resistance. There were no changes in cardiac index, heart rate, or cardiac filling pressures. ANP caused no changes in myocardial blood flow or its distribution, and caused no changes in myocardial oxygen extraction. Regional myocardial lactate uptake (RMLU) and extraction (RMLE) increased significantly (P < 0.05) at 50 ng.kg-1.min-1 (10.2 +/- 3.8 mumol/min and 8.2% +/- 3.0%, respectively) as compared to control (-1.1 +/- 3.0 mumol/min and -1.3% +/- 3.3%, respectively). RMLE and RMLU were significantly (P < 0.05) higher with ANP (5.7% +/- 2.5% and 6.8 +/- 3.7 mumol/min, respectively) compared to SNP (-1.5% +/- 2.1% and -0.1 +/- 3.7 mumol/min, respectively). We conclude that ANP has no dilatory effects on coronary vascular resistance vessels and thus lacks the potential to maldistribute flow, and that ANP improves myocardial lactate metabolism after CABG.