The peak velocities measured by c-TVI are about 15–20% lower than those measured by pulsed Doppler echocardiography, but the measurements can be used interchangeably for velocity profile recording and for timing of events. In both animal experiments 11 and human studies, 12 colour tissue Doppler velocity imaging (c-TVI) reflects myocardial contractility by measuring the movement of cardiac tissue. However, improved interventricular and intraventricular coordination of contraction has been shown using gated blood pool scintigraphy 9 and echocardiographic phase analysis of the left ventricle in the short axis. The mechanisms responsible for the haemodynamic improvement achieved by biventricular pacing are still not entirely clear. Beneficial acute haemodynamic effects of biventricular pacing have been shown, consisting of a reduction in pulmonary capillary wedge pressure and an improvement in peak dP/dt without an increase in oxygen consumption 1– 4, as have long term clinical benefits in terms of improvements in the six minute hall walk test (6MHWT), New York Heart Association (NYHA) functional class, maximum oxygen consumption, and quality of life indices. The use of biventricular pacing in patients with heart failure and bundle branch block has increased rapidly in recent years. A change to a more synchronous longitudinal left ventricular movement pattern during biventricular pacing was demonstrated. The diastolic movement pattern remained unchanged from baseline to follow up.Ĭonclusions: c-TVI showed a significant asynchronous regional longitudinal movement of basal left ventricular sites at baseline. After resynchronisation by biventricular pacing those regional movements were separated by an average of only 7 ms at the basal site, but there was still a 21 ms earlier movement of the left ventricular free wall in the mid left ventricular site. At baseline the peak main systolic tissue velocities in the left ventricular free wall were typically delayed by an average of 42 ms in the basal left ventricular site and by 14 ms in the mid left ventricular site compared with the corresponding sites in the interventricular septum. Results: From baseline to follow up, mean peak tissue velocities changed only during isovolumic contraction in the basal interventricular septum and the left ventricular free wall. Regional left ventricular peak tissue velocities and regional time differences during the cardiac cycle were compared in the basal and mid interventricular septal segments of the left ventricle, and in the corresponding segments in the left ventricular free wall. Eighteen patients were studied from an apical four chamber view at baseline and after a one month follow up of biventricular pacing. Objective: To quantify ventricular resynchronisation by biventricular pacing using colour tissue Doppler velocity imaging (c-TVI).ĭesign and patients: c-TVI shows regional tissue velocity profiles with a very high time resolution (10 ms).
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