Mechanism of cardiac functional improvement by biventricular pacing

Research Project

Project/Area Number	13670730
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	Circulatory organs internal medicine
Research Institution	Kagoshima University
Principal Investigator	OTSUJI Yutaka Kagoshima University, University Hospital, Faculty of Medicine, Associate Professor, 医学部附属病院, 講師 (30264427)
Co-Investigator(Kenkyū-buntansha)	TEI Chuwa Kagoshima University, University Hospital, Faculty of Medicine, Professor, 医学部, 教授 (10163891) MINAGOE Shinichi Kagoshima University, University Hospital, Faculty of Medicine, Associate Professor, 医学部, 助教授 (90190694)
Project Period (FY)	2001 – 2002
Project Status	Completed (Fiscal Year 2002)
Budget Amount *help	¥400,000 (Direct Cost: ¥400,000) Fiscal Year 2002: ¥400,000 (Direct Cost: ¥400,000)
Keywords	Biventricular pacing / Functional mitral regurgitation / 虚血性僧帽弁逆流 / 両室ペーシング / 心エコー法 / functional mitral regurgitation
Research Abstract	Left ventricular (LV) dysfunction was induced in an anesthetized and open chest pig by infusion of esmolol (400 - 500 μg/kg/min) and phenylephrine (200 - 300 μg/kg/min), and mild but significant functional mitral regurgitation (MR) was created. The heart rate was kept constant (100 beats/min) by atrial pacing. LV function was evaluated by LV peak + and -dP/dt. MR was quantified by proximal isovelocity surface area (PISA) method. Addition of right ventricular pacing (atrio-ventricular sequential pacing) resulted in significant decrease in LV peak + dP/dt (1192±30 to 874±178, p<0.01) and LV peak - dP/dt (- 829±78 to - 744±148, p<0.01), which was accompanied by significant increase in MR volume (4.2±2.4 to 12.0±2.7 ml/beat, p<0.01). Addition of LV pacing (biventricular pacing) failed to improve LV function (LV + dP/dt: 874±178 to 798±64, n.s., LV-dP/dt: -744±148 to - 681±91, n.s.) and MR volume did not significantly changed either (12.0±2.7 to 13.0±5.1 ml/beat, n.s.). These results suggest that LV dysfunction by asynchrony with reduced peak LV + and - dP/dt results in worsening of functional MR. Cardiac re-synchronization therapy with biventricular pacing is expected to improve LV dysfunction and worsened functional MR by asynchrony, however, it was not effective in this animal model, requiring further investigations.