[Echocardiographic study of left ventricular performance during sitting bicycle exercise (author's transl)]

Abstract

Twelve healthy volunteers, mean age 25.4 +/- 4.18 years, performed sitting bicycle ergometer graded exercise to exhaustion. Recordings of left ventricular echocardiographic dimension, heart rate, arterial blood pressure, were obtained at rest and at two minutes intervals during exercise and recovery. Echocardiographic tracings were digitized and the values of three complexes were combined and means determined for the overall analysis. Heart rate increased from 76.92 +/- 15.09 to 154.91 +/- 12.13 (p less than 0.001) at peak exercise and decreased to 98.50 +/- 11.60 (P less than 0.001) at six minutes recovery. Similarly behaved blood pressure. End diastolic Echo dimension varied significantly from 46.50 +/- 4.66 mm to 51.44 +/- 5.38 mm (P less than 0.005) at peak exercise and to 45.91 +/- 4.52 mm (P less than 0.005) at six minutes recovery, but resulted unchanged at lower levels of exercise. It started to return towards resting values, from two to four minutes of recovery. End systolic dimension did not change significantly at any heart rate. Shortening fraction increased progressively and significantly at every step of exercise, decreasing in the same way during recovery: rest 38.42 +/- 3.62%; peak exercise 44.28 +/- 5.32% (P less than 0.005); end recovery 39.28 +/- 5.89% (P less than 0.001). So did respectively: Stroke volume (Teichholtz) 69.50 +/- 12.16 cc; 84.92 +/- 24.14 cc (P less than 0.005); 67.64 +/- 16.48 cc (P less than 0.005). Cardiac output 5.27 +/- 1.18 lt/min; 12.46 +/- 3.83 (P less than 0.001); 6.25 +/- 1.00 (P less than 0.005). Ejection fraction 68.33 +/- 4.68%, 78.58 +/- 8.80 (P less than 0.001); 68.82 +/- 8.16 (P less than 0.005). Mean normalized velocity of circumferential fibre shortening 1.33 +/- 0.25 circ/sec; 2.37 +/- 0.33 (P less than 0.001); 1.55 +/- 0.031 (P less than 0.001). These results indicate that in untrained healthy subjects, variations of cardiac output during exercise and recovery depend mainly on heart rate and left ventricular fibre shortening rate. Severe exertion produces an increase of left ventricular dimension due to a Frank-Starling effect. Sitting bicycle exercise Echocardiography appears to be a suitable method to assess Left ventricular performance with a chest position relevant to normal human conditions.