A Comparison of the Acute Phase Cardiac Function Between Septal and Apical Right Ventricular Pacing in Individual Patients

In recent years right ventricular septal pacing (RVSP) has been performed instead of right ventricular apical pacing (RVAP) because of the detrimental effects on the ventricular function associated with the latter type of pacing. However, little information has been available on the comparison of the cardiac function between RVAP and RVSP in individual patients. Therefore, we compared the changes in the cardiac index (CI) between RVAP and RVSP (right ventricular outflow tract or mid-ventricular tract) in each patient in whom a permanent pacemaker was implanted. We measured both the QRS duration and acute phase of the cardiac function by means of a Swan-Ganz catheter and compared the results between RVAP and RVSP. RVSP was associated with a shorter QRS duration (139. 5 +/- 4.6 vs. 180.6 +/- 4.6 msec, p < 0.0001) in comparison to RVAP. Although there was no significant difference in the CI between the 2 pacing positions (2.71 +/- 0.12 vs. 2.74 +/- 0.13 L/min/m(2), p +/- 0.6969), the CI among the patients with complete atrioventricular block (cAVB) had a strong tendency of being better with RVSP patients (2.65 +/- 0.19 vs. 2.84 +/- 0.19 L/min/m(2), p +/- 0.1444). It is suggested that the beneficial effect of RVSP differs according to the causal disorder for pacemaker implantation.