The Effects of Pulmonary Arterial Hypertension on Left Ventricular Systolic and Diastolic Synchrony

Abstract

Purpose: Pulmonary arterial hypertension (PAH) is known to alter right ventricular (RV) function and mechanics, resulting in RV dyssynchrony. However, the effects of PAH on left ventricular (LV) mechanics are less well known. We therefore queried our tissue Doppler imaging (TDI) database to identify patients with chronic PAH who had normal QRS duration and normal LV ejection fraction to examine the effect of PAH on LV systolic and diastolic synchronicity. Methods: The mid LV septum and lateral wall were sampled, as seen in Figure 1A, to obtain a TDI velocity signal. Systolic synchronicity was determined by the time interval between peak TDI systolic velocities (Ss) while diastolic synchronicity was defined as the time interval between peak TDI early (E) wave diastolic signals in 2 groups of patients. Figure 1B is a sample TDI velocity signal from a normal patient (Group I) and Figure 1C is a sample from a patient with PAH (Group II). Group I consisted of 18 patients (57 ± 16 years) with chronic PAH (PA systolic pressure of 78 ± 20 mmHg) and Group II included 18 healthy volunteers (47 ± 14 years; p = NS and PA systolic pressure of 21 ± 4 mmHg; p<0.001). Results: There was no difference between Group I and II regarding LV ejection fraction (79 ± 12% vs 65 ± 5%) or QRS duration (89 ± 14 ms vs. 90 ± 7 ms). However, Group I patients had significantly longer temporal delay between their septal and LV lateral wall systolic TDI signals (41 ± 36 ms vs. 8 ± 12ms; p<0.001) as well as their early diastolic E wave TDI signals (45 ± 56ms vs. 11 ± 9ms; p<0.01) than Group II as seen in Figure 1D and 1E. Conclusions: Systolic as well as early diastolic dyssynchrony is present in PAH patients despite having normal LV ejection fraction and a narrow QRS duration. It appears that geometric alterations in RV anatomy, due to pressure overload, rather than a electromechanical coupling delay in these patients not only impair LV systolic mechanics but also early LV relaxation. Further studies are now needed to determine the temporal evolution of these alterations and their relation to clinical outcomes.