Breathlessness in pulmonary hypertension: heart and lung?

Abstract

As exertional breathlessness is considered the main in these two patients. The pattern of left ventricular outflow exercise limiting problem in heart failure and pulmonary hypertension we assessed two patients with long standing pulmonary hypertension using pharmacological stress echocardiography. We found their exertional breathlessness to be disproportionate to raised pulmonary artery pressure (70 mm Hg) and in one patient exertion was associated with presyncope. The two patients were in sinus rhythm and had some degree of left ventricular hypertrophy due to systemic hypertension but significant mitral regurgitation was absent. A physiological stress echocardiogram confirmed the development of significant left ventricular outflow tract obstruction and both patients developed systolic anterior movement of the mitral valve (SAM) and peak outflow tract gradient of over 100 mm Hg. This was associated with a 30 mm Hg drop in systolic blood pressure and breathlessness but only a modest increase in right sided pressure of 10 mm Hg. The main cause of breathlessness in pulmonary hypertension is low cardiac output and ventilatory inefficiency occurring initially with exertion but later on at rest. The two patients studied had narrowed left ventricular outflow tract, partially contributed to by the reversed septal motion (an echocardiographic feature of pulmonary hypertension) and partially by left ventricular hypertrophy. The combination of a smallish left ventricular cavity and fast heart rate resulted in outflow tract obstruction and hypotension. This did not cause a significant increase in left atrial pressure as shown by the pattern of left ventricular filling, nor significantly raised right ventricular pressure. It appears that the outflow tract obstruction and drop in systolic blood pressure are the main contributing factors for stress induced breathlessness