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Chronic Effect of Oral Mexiletine Administration on Left Ventricular Contractility in Patients with Congestive Heart Failure: A Study Based on Mitral Regurgitant Flow Velocity Measured by Continuous‐Wave Doppler Echocardiography
Author(s) -
Morita Hisaki,
Hirabayashi Koichi,
Nozaki Shiro,
Ohmori Koji,
Yoshikawa Kei,
Matsuo Hirohide
Publication year - 1995
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1002/j.1552-4604.1995.tb04091.x
Subject(s) - medicine , cardiology , heart failure , contractility , doppler echocardiography , mexiletine , doppler effect , anesthesia , diastole , blood pressure , physics , astronomy
The long‐term effect of mexiletine on left ventricular (LV) contractility in patients with congestive heart failure is not clear. The authors therefore measured LV contractility before and after continuous oral administration of mexiletine in patients with congestive heart failure accompanied by mitral regurgitation (MR) using Doppler echocardiography. The study population consisted of 8 patients with congestive heart failure (6 due to dilated cardiomyopathy and 2 due to old myocardial infarction) accompanied by significant functional MR who had more than 1000 ventricular premature contractions (VPCs) per day or Class IV Lown classification arrhythmias before mexiletine administration. The LV contractility was evaluated by calculating a Doppler‐derived index, the rate of increase in LV pressure during the isovolumic contraction time (ICT ΔP/Δt), which has been confirmed to be nearly equal to LV Max dP/dt. The increase in LV pressure (ΔP) between 1 and 3 m/sec of the MR flow velocity as measured by continuous‐wave Doppler echocardiography was calculated using the simplified Bernoulli's equation, and ICT ΔP/Δt was derived by dividing ΔP by the time required for this change. The left ventricular ejection fraction and the left ventricular and left atrial dimensions also were measured by echocardiography. These parameters were obtained before and after 2 to 4 weeks of daily oral administration of mexiletine 300 mg. Values of ICT ΔP/Δt were 640 ± 202 mm Hg/sec and 650 ± 210 mm Hg/sec before and after mexiletine administration, respectively, showing no change. The left ventricular ejection fraction and the left ventricular and left atrial dimensions also were unchanged. These findings indicate that continuous oral administration of mexiletine has no effect on LV contractility in patients with congestive heart failure.