Thirty-seven patients with dyspnea, clinical chronic obstructive pulmonary disease and abnormal pulmonary function tests demonstrating an obstructive airways pattern underwent six-foot posteroanterior chest radiography, radionuclide ventriculography and sphygmomanometer-monitored arterial pressure response during a bedside Valsalva maneuver. Patients could be separated into three groups (square wave, absent overshoot, sinusoidal) on the basis of their Valsalva response which corresponded to left ventricular ejection fractions on radionuclide ventriculography of 0.19 +/- 0.05, 0.42 +/- 0.20, 0.64 +/- 0.13 (p less than 0.005 for differences between all group means). Pulmonary function test results and a detailed patient history could not accurately separate patients with primary pulmonary dyspnea from those with concomitant left ventricular dysfunction (ejection fraction less than 0.50). In this population of patients, however, both the sensitivity (88 percent) and predictive value (88 percent) for the presence of left ventricular dysfunction of an abnormal (square wave or absent overshoot) systolic arterial pressure response during Valsalva maneuver were high. Thus, in dyspneic subjects with clinical evidence of chronic obstructive airways disease, concomitant left ventricular dysfunction can be accurately diagnosed using the simple Valsalva maneuver without sophisticated equipment or highly trained personnel.