Atrial natriuretic peptide in severe heart failure: response to controlled changes in atrial pressures during intravenous nitroglycerin therapy.
Atrial natriuretic peptide (ANP) levels were measured in 17 patients with severe congestive heart failure (New York Heart Association functional class IV), and the response of the peptide was studied during changes in cardiac filling pressures induced by a 24-hour infusion of nitroglycerin. In the control state plasma ANP levels (687 +/- 551 pg/ml) were 10-fold normal. During the administration of nitroglycerin, natriuretic peptide levels decreased (p less than 0.005) with changes matching very closely the decreases in pulmonary arterial wedge and right atrial pressures, a 1% mean decrease in the peptide level for every 1.5 to 2% mean change in atrial filling pressures. In patients with hemodynamic tolerance to constant-dose nitroglycerin infusion, the resulting increase in atrial pressures was accompanied by an appropriate secondary increase in the plasma ANP level. During the 24-hour study period there was a direct linear relationship between both wedge (r = 0.93, p = 0.007) and right atrial (r = 0.93, p = 0.008) pressures and the plasma ANP level, with a zero-pressure ANP intercept near normal (69 pg/ml for wedge, 174 pg/ml for right atrial pressure). The findings were no different in a subgroup of five patients receiving simultaneous treatment with captopril, except that plasma renin activity was higher and the aldosterone level lower than in the control group by a factor of approximately 2.5. The close relationship and tracking of atrial pressure and natriuretic peptide curves suggested that the sensitivity of the atrial stretch response to changes in atrial filling pressures was maintained in severe congestive heart failure.