Effects On Left Atrial Structures And Function After Right Ventricular Outflow Tract Pacing And Right Ventricular Apex Pacing

Objective To compare the effects of right ventricular apex(RVA) pacing and right ventricular outflow tract(RVOT) pacing on left atrial structures and function by echocardiograph. Methods Fotry-six patients with sick sinus syndrome or high atrioventricular block who had been accepted the dual-chamber cardiac pacing were subjected to echocardiography before, three month and one year after operation. They were divided into two groups according to the pacing site in the right ventricle, RVOT pacing group(23patients) and RVA pacing group(23patients). The left atrial pre-systolic volume (LAVp), the left atrial maximal volume (LAVmax), the left atrial minimal volume (LAVmin), the left atrial active emptying fraction (LAAEF), the left atrial passive empting fraction (LAPEF) and the left ventricular ejection fraction(LVEF) were measured. The late diastolic strain rate(SRa), the systolic strain rate(SRs) and the early diastolic strain rate(SRe) of each left atrium wall were measured by strain rate imaging(SRI). Results Three months after opearation, compared with the RVOT group, SRa and SRs increased, SRe decreased in the RVA group. The other indexes has no significant difference between two groups. One year after operation, compared with the RVOT group, LAVp, LAVmin, LAVmax, LAAEF, SRa and SRs increased significantly (P<0.05), meanwhile SRe, LAPEF and LVEF decreased significantly (P<0.05) in the RVA group. Compared to before operation, LVEF changing rate correlated negatively with the changing rate of SRa (r=-0.531, P<0.01). Conclusions Compared with the RVOT group, the structure and function of the left atrium in the RVA group had some change after dual-chamber cardiac pacing:the left atrial volume was increased, the left atrial storage function was increased, the left atrial active contraction function was increased and the left atrial conduit function was decreased after right ventricular apex pacing. Strain and strain rate imaging can be used to access left atrial function, which can earlier reflect changes of the left atrial function.