Increased Pulmonary Vascular Resistance in Early Stage Systemic Hypertension: A Resting and Exercise Stress Echocardiography Study

Background: In early stage uncomplicated systemic hypertension (HT), increased pulmonary vascular resistance (PVR) has been reported at rest, but more rarely during exercise. Recently, limits of normal for stress echocardiography in the evaluation of the pulmonary circulation have been better defined. We therefore used this approach to assess the pulmonary circulation in early HT. Methods: One hundred thirteen patients with mild to moderate untreated, uncomplicated HT (blood pressure, 152 +/- 19/89 +/- 11 mm Hg, heart rate, 70 +/- 13 beats per minute) and 345 age-and sexmatched healthy control subjects underwent resting Doppler echocardiography with estimation of mean pulmonary arterial pressure (mPAP), left atrial pressure (LAP), and cardiac output (CO). Measurements were repeated at exercise stress test in 25 patients from each group. Results: At rest, hypertensive patients had normal right and left ventricular structure and function, higher systemic vascular resistance, mPAP (16 +/- 5 vs 14 +/- 5 mm Hg; P < 0.0001), and PVR (1.3 +/- 1.1 vs 1.0 +/- 1.2 Wood units; P = 0.006) than control participants, but similar LAP. During exercise, hypertensive patients showed a lower maximum workload and CO and higher peak mPAP than control subjects, but a similar increase in LAP. PVR determined according to multipoint mPAP-CO relationships was also higher in hypertensive patients than in control subjects (2.5 +/- 1.1 vs 1.5 +/- 0.7 mm Hg/L/min; P < 0.05), with no changes in pulmonary resistive vessel distensibility coefficient a (0.012 +/- 0.007 vs 0.012 +/- 0.010% change in diameter for each mm Hg increase in mPAP). Conclusions: Resting and exercise PVR are increased in uncomplicated HT, without this being related to increased pulmonary venous pressure or resistive vessel stiffness, suggesting an early increase in pulmonary vascular tone.