Pierre Cosnay

Characterization of right or left ventricular contraction heterogeneity using Fourier phase analysis

The standard deviation of the first harmonic Fourier phase histogram is an indicator of the contraction heterogeneity of the heart ventricles. This approach has been applied to analyse tomographic blood pool (99mTc) examinations in a group of 32 patients with angiographically verified mainly right (RV) but also left (LV) kinetic disorders in relation to severe ventricular arrhythmias and suspicion of arrhythmogenic right ventricular dysplasia (ARVD). The reference group consisted of ten patients with low probability of cardiac kinetic abnormalities.Thick tomographic slices including both ventricles have been reconstructed in the horizontal long axis orientation from a series of 32 gated projections recorded over a 360° rotation. Separately for each ventricle the Fourier phase histograms have been computed and characterized by their standard deviations (PSD). Normal values (mean±standard deviation, LV=11°±5°, RV=12°±5°) were significantly lower (P<0.01 and P<0.001) than those measured in abnormal cases (LV=19°±10° and RV=31°±17°).Detailed analysis of the data supports the hypothesis of a primary RV disease in ARVD, with secondary LV extension. PSD seems to be a good predictor of an organic cardiac disease underlying ventricular arrhythmias and may be used for screening the patients.

Evaluation of bepridil efficacy by electrophysiologic testing in patients with recurrent ventricular tachycardia: Comparison of two regimens

SummaryThe purpose of the study was to evaluate this effect of different doses of intravenous and oral bepridil on the induction of ventricular tachycardia. Thirty-eight patients underwent electrophysiologic evaluation for recurrent ventricular tachycardia (VT). Sustained monomorphic VT was induced by programmed ventricular stimulation, using up to three extrastimuli in all patients. The effects of intravenous bepridil (2 mg/kg) were evaluated during the initial study. Intravenous bepridil prevented the induction of sustained VT in eight patients (21%). Electrophysiologic study was repeated after oral bepridil. In six patients the study was stopped because of adverse effects or VT recurrence. Thirty-two patients underwent repeat study 7 days later, taking oral bepridil, 500 mg/day (n=16) or 900/day (n=16). A dose of 500 mg/day of bepridil prevented the induction of sustained VT in only one patient. A dose of 900 mg/day of bepridil prevented the induction of sustained VT in eight patients. There were no significant clinical adverse effects, except in one patient receiving intravenous bepridil. The response to intravenous bepridil did not predict the response to oral bepridil. The response to intravenous or oral bepridil was not related to the plasma level of bepridil but was related to a higher left ventricular ejection fraction. Eight patients (21%) in whom VTs were noninducible on oral bepridil were discharged on 300 mg/day of bepridil if their initial loading dose was 500 mg/day or on 600 mg/day if their initial loading dose was 900 mg/day. They remained free of VT during a follow-up of at least 6 months. In conclusion, this study suggests that oral bepridil at the dose of 600 mg/day may be of value in patients with recurrent VT.

Phase quadrature shift between left and right ventricles during a ventricular tachycardia attack

Equilibrium gated nuclear angiography was performed on a patient during an attack of ventricular tachycardia and then after conversion to sinus rhythm. Global and regional wall motion was assessed by means of isocontours, Fourier phase analysis and factor analysis. Ventricular phase histograms showed a 100° difference between ventricles: left ventricular filling time occurred during right ventricular contraction. The earliest phase was located in the septum and the sequence of activation showed a large delay of left ventricular activation. After conversion to sinus rhythm, a right bundle branch block was observed, being almost the inverse of the latter situation.