VO2 Max and anaerobic threshold in hypertension: a tissue Doppler study

Hypertension can impair left ventricular (LV) relaxation causing shortness of breath and reduced exercise capacity, which may affect the clinical evaluation of the symptomatic hypertensive patient. In this study we used tissue Doppler imaging (TDI) to identify correlates of anaerobic threshold (AT) and maximum oxygen uptake (VO2 Max). Our goal was to assess the feasibility of TDI as a surrogate of functional capacity in hypertensive individuals.

We studied subjects without metabolic syndrome and with normal LV function (ejection fraction (EF) >50%). Traditional echocardiographic variables were obtained before and after a cardiopulmonary exercise test. Systolic (S) and diastolic (E'and A') myocardial velocities were measured at the basal septal (bs) and posterior (bp) walls.

After multivariate analysis, resting E'bp (r =0.56, P < 0.002) and isovolumic relaxation time (IVRT) (r =-0.49, I < 0.03) correlated with VO2 Max, while A Valsalva correlated with AT (r =-0.46, P < 0.03). Peak stress E'/A'bp correlated with age and gender corrected METs (r =-0.63, P < 0.0004) and VO2 Max (r =-0.39, P< 0.04).

Resting E'bp and peak stress E'/A'bp correlate with VO(2) Max in hypertensive patients. TDI may be an important tool when assessing symptoms in this population.