The Value of Monitoring Pulmonary Artery Pressure for Early Detection of Left Ventricular Failure Following Myocardial Infarction

Abstract

Flow-directed catheters recorded serial changes in mean pulmonary artery pressure (PA) every 4 to 6 hours in 25 patients during the first 4 or 5 days following acute myocardial infarction. On the basis of the PA on admission, patients were divided into three groups. Patients in group 1 had normal PA (10-20 mm Hg) and maintained a stroke volume index (SVI)>35 ml/min/m², a pulmonary artery oxygen saturation (MVSO₂)>70%, and a normal cardiac index, arterial oxygen saturation, pH, and PCO_CO2. They developed only minor arrhythmias, no heart failure, and none died. Group 3 consisted of one patient with abnormally low PA (20 mm Hg) who maintained this elevation over the first 48 hours of monitoring, or showed progressive elevation prior to this, had SVI2, MVSO₂2, arterial desaturation, and respiratory alkalosis. They demonstrated clinical evidence of heart failure, had major arrhythmias, and 25% died. Three patients with elevated PA on admission spontaneously returned this pressure to normal over the first 48 hours of monitoring. Each of these patients maintained normal hemodynamics and had a good prognosis. PA was always elevated prior to the usual clinical signs of left ventricular failure. We conclude that PA provides a reliable early objective measure of left ventricular failure and is, therefore, an excellent guide to therapy.