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  • Title: Effects of abnormal activation on the time course of the left ventricular pressure pulse in dilated cardiomyopathy.
    Author: Xiao HB, Brecker SJ, Gibson DG.
    Journal: Br Heart J; 1992 Oct; 68(4):403-7. PubMed ID: 1449925.
    Abstract:
    OBJECTIVE: To investigate the effects of QRS duration on characteristics of the left ventricular pressure pulse derived from the time course of functional mitral regurgitation by continuous wave Doppler. DESIGN: Retrospective and prospective study of 50 patients with dilated cardiomyopathy, by electrocardiography, echocardiography, and Doppler cardiography. SETTING: Tertiary cardiac referral centre. PATIENTS: 50 patients (mean age (SD) 58 (16)) with dilated cardiomyopathy, all with functional mitral regurgitation. RESULTS: The values of QRS duration ranged widely, from 70 to 190 ms with a mean value of 110 ms, and were unimodally distributed. The overall duration of mitral regurgitation correlated positively with QRS time (r = 0.65) over the entire range of values. When the duration of mitral regurgitation was divided into contraction, aortic ejection, and relaxation times, increased QRS duration prolonged contraction (r = 0.51) and relaxation (r = 0.52) times. Aortic ejection time was affected by RR interval (r = 0.74). Duration of QRS correlated negatively with peak rate of rise in left ventricular pressure (+dP/dt) (r = -0.48), and positively with the time intervals from Q to peak pressure (r = 0.49) and to peak +dP/dt (r = 0.72), and also with those from the start of mitral regurgitation to peak pressure (r = 0.49) and to peak +dP/dt (r = 0.76). Duration of QRS did not directly affect the peak rate of left ventricular pressure fall (-dP/dt), or the isovolumic relaxation period. CONCLUSIONS: Values of QRS duration are unimodally distributed in patients with dilated cardiomyopathy, without evidence of a discrete group of patients with left bundle branch block. Prolonged QRS duration reduces peak +dP/dt, prolongs overall duration of the pressure pulse, the time to peak +dP/dt, and relaxation time. Duration of QRS must therefore be taken into account in assessing standard measurements of myocardial function in patients with dilated cardiomyopathy.
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