Central and peripheral haemodynamic determinants of effort tolerance in patients with heart failure.

We studied central and peripheral hemodynamics and exercise tolerance in 24 patients with left ventricular dysfunction. All were in NYHA class II or III, and echocardiographic left ventricular ejection fraction was < 35% without pharmacologic influences. Patients underwent to treadmill test (Naughton protocol), cardiopulmonary upright bicycle test, and supine bicycle test with haemodynamic measurements. All tests were exhaustive. Average exercise time was 9 +/- 3.4 min, (range 3-20). Average ejection fraction (.28 +/- 0.65) dis not correlate with working capacity (r = .32), nor did left ventricular filling pressure (pulmonary capillary wedge pressure) at rest and at peak exercise (r = .29 and r = .02). Stroke volume and stroke volume index were on average depressed, with no variations during work; cardiac output and cardiac index were also depressed, with a significant increase at peak exercise (both p < .001). Systemic and pulmonary resistances were increased, but systemic resistances tended to decrease during effort (p < .001), while pulmonary resistances did not (p = NS). We subdivided patients according to systemic vascular resistances lower or higher than 1500 dynes.cm.sec-5 at rest; this identifies two different working capacities (low systemic vascular resistances 11.7 +/- 4.4 min, high systemic vascular resistances 6.9 +/- 3.2 min, p < .05). Patients were then divided in two groups: group I (rest stroke volume > 60 ml) and group II (rest stroke volume < 60 ml). Group I worked 11 +/- 5 min, group II 8.5 +/- 3 min (p < .05). We performed a linear regression analysis between cardiac output and systemic vascular resistances at rest and during exercise in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)