Relations of Doppler Stroke Volume and Its Components to Left Ventricular Stroke Volume in Normotensive and Hypertensive American Indians: The Strong Heart Study

Abstract Doppler echocardiographic measurement of time-velocity integral of blood flow across the aortic annulus (“stroke distance”) or of stroke volume (SV) have been proposed as noninvasive measures of cardiac pump performance that could elucidate the hemodynamics of hypertension. To evaluate the performance of these measures of hemodynamic volume load in a population with a wide range of body build and other characteristics, we obtained technically adequate imaging and Doppler echocardiograms in 1,935 of 2,212 (87%) American Indian Strong Heart Study participants, without mitral regurgitation or segmental left ventricular (LV) dysfunction, in Arizona, Oklahoma, and South/North Dakota. The subjects ranged widely in age (48 to 81 years) and body mass index (17.0 to 62.6 kg/m2); 65% were women; 1,161 were normotensive and 774 were hypertensive. As a reference standard, LV and stroke volumes were calculated from LV internal dimensions by the Teichholz method. Doppler SVs were moderately related to LV SVs (r = 0.63), but Doppler SV was slightly lower in both normotensive (mean = 69.8 and 72.9 mL, respectively) and hypertensive subjects (71.1 v 73.6 mL). Aortic stroke distance was less closely related than was aortic annular area to LV SV (r = 0.34 v 0.40, P< .001). Aortic annular area (r = 0.44) but not stroke distance (r = 0.04) was moderately correlated with body surface area. Stroke distance was inversely related to annular area (r = −0.29) and in subjects stratified by aortic annular diameter 1.6 to 1.9, 2.0 to 2.1, and 2.3 to 2.9 cm, mean LV SV increased from 67 to 74 to 80 mL, but average stroke distance fell from 22.8 to 21.6 to 20.1 cm. Stroke distance also failed to identify gender differences in LV SV but did identify that due to obesity. Thus Doppler SV closely parallels independently measured LV SV but slightly underestimates SV in both normotensive and hypertensive adults, whereas aortic stroke distance yields misleading comparisons between genders or individuals of different body sizes.