Combined longitudinal and radial dyssynchrony predicts ventricular response after resynchronization therapy.

OBJECTIVES: The purpose of this study was to test the hypothesis that a combined echocardiographic assessment of longitudinal dyssynchrony by tissue Doppler imaging (TDI) and radial dyssynchrony by speckle-tracking strain may predict left ventricular (LV) functional response to cardiac resynchronization therapy (CRT). BACKGROUND: Mechanical LV dyssynchrony is associated with response to CRT; however, complex patterns may exist. METHODS: We studied 190 heart failure patients (ejection fraction [EF] 23 +/- 6%, QRS duration 168 +/- 27 ms) before and after CRT. Longitudinal dyssynchrony was assessed by color TDI for time to peak velocity (2 sites in all and 12 sites in a subgroup of 67). Radial dyssynchrony was assessed by speckle-tracking radial strain. The LV response was defined as > or =15% increase in EF. RESULTS: One hundred seventy-six patients (93%) had technically sufficient baseline and follow-up data available. Overall, 34% were EF nonresponders at 6 +/- 3 months after CRT. When both longitudinal dyssynchrony by 2-site TDI (> or =60 ms) and radial dyssynchrony (> or =130 ms) were positive, 95% of patients had an EF response; when both were negative, 21% had an EF response (p < 0.001 vs. both positive). The EF response rate was lowest (10%) when dyssynchrony was negative using 12-site TDI and radial strain (p < 0.001 vs. both positive). When either longitudinal or radial dyssynchrony was positive (but not both), 59% had an EF response. Combined longitudinal and radial dyssynchrony predicted EF response with 88% sensitivity and 80% specificity, which was significantly better than either technique alone (p < 0.0001). CONCLUSIONS: Combined patterns of longitudinal and radial dyssynchrony can be predictive of LV functional response after CRT.

Nitroglycerin improves left ventricular relaxation by changing systolic loading sequence in patients with excessive arterial load.

Nitroglycerin abbreviates left ventricular (LV) relaxation through improved hemodynamics as well as by direct actions on the myocardium. The aim of this study was to examine whether the changing systolic loading sequence during nitroglycerin administration affects LV relaxation in patients with excessive arterial load. By use of a conductance catheter with microtip manometer, the effects of intravenous nitroglycerin (0.3-0.5 microg/kg/min) on LV function and hemodynamics were examined in 39 patients with various degrees of LV contractility. Patients were divided into two groups according to LV-arterial coupling, the ratio of end-systolic elastance (Ees) to effective arterial elastance (Ea). In patients with Ees/Ea ratio > 1, nitroglycerin had no effect on the time to peak force or on the time constant of LV relaxation (tau). On the other hand, in patients with Ees/Ea < 1, which represented excessive arterial load, nitroglycerin significantly shortened the time to peak force, shifted the peak of the loading sequence from late to early systole, and significantly decreased tau without any changes in Ees. Thus, nitroglycerin improved LV relaxation in patients with excessive arterial load partly by changing the systolic loading sequence.