Restoration of ventricular septal hypoperfusion by cardiac resynchronization therapy in patients with permanent right ventricular pacing.
BACKGROUND
Pacing from the right ventricular apex (RVA) is associated with cardiac dysfunction and shows electrophysiological features similar to left bundle branch block in which left ventricular (LV) mechanical dyssynchrony impairs septal coronary artery perfusion.


METHODS
A total of 62 non-ischemic patients with an implanted pacemaker at the RVA with a pacing rate of >95% were studied. LV septal coronary perfusion as indicated by the LV septal perfusion index was measured by electrocardiography (ECG)-gated single-photon emission computed tomography for all patients at baseline and for patients who were upgraded to CRT at 6months after CRT. Relationships among LV septal perfusion index, QRS duration, and LV ejection fraction were analyzed.


RESULTS
Among the patients with permanent RVA pacing, 28 of 62 (45%) had impaired septal perfusion (i.e., septal perfusion index <0.9). The LV septal perfusion index was significantly correlated with both QRS duration (r=-0.763, p<0.001) and LV ejection fraction (r=0.462, p=0.001). Eleven patients were upgraded to CRT. CRT significantly improved the LV septal perfusion index from 0.63 (SD=0.13) to 0.89 (SD=0.19) (p<0.001)and cardiac function: LV end-systolic volume from 102.3mL (SD=70.0) to 179.7mL (SD=118.4) (p=0.002) and LV ejection fraction from 22.5 (SD=8.9%) to 38.4% (SD=13.9%) (p=0.001).


CONCLUSIONS
Nearly half of the non-ischemic patients with permanent RVA pacing presenting with prolonged QRS duration and LV dysfunction developed LV septal hypoperfusion. Both septal perfusion and LV function improved in patients who were upgraded to CRT.
Department of Cardiovascular Medicine, Shizuoka Medical Center, 762-1 Nagasawa, Shimizu, Sunto Shizuoka 4110906, Japan. Electronic address: m-ogano@nms.ac.jp.
Michio
M
Ogano
Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo, Tokyo 1138603, Japan.
Yu-Ki
YK
Iwasaki
Department of Cardiovascular Medicine, Shizuoka Medical Center, 762-1 Nagasawa, Shimizu, Sunto Shizuoka 4110906, Japan.
Jun
J
Tanabe
Department of Cardiovascular Surgery, Shizuoka Medical Center, 762-1 Nagasawa, Shimizu, Sunto Shizuoka 4110906, Japan.
Hisato
H
Takagi
Department of Cardiovascular Surgery, Shizuoka Medical Center, 762-1 Nagasawa, Shimizu, Sunto Shizuoka 4110906, Japan.
Takuya
T
Umemoto
Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo, Tokyo 1138603, Japan.
Meiso
M
Hayashi
Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo, Tokyo 1138603, Japan.
Yasushi
Y
Miyauchi
Department of Cardiovascular Medicine, Nippon Medical School, 1-1-5 Sendagi, Bunkyo, Tokyo 1138603, Japan.
Wataru
W
Shimizu
D000368:Aged; D000369:Aged, 80 and over; D058406:Cardiac Resynchronization Therapy / Q000009:adverse effects / Q000379:methods; D003331:Coronary Vessels / Q000503:physiopathology*; D004452:Echocardiography / Q000379:methods; D004562:Electrocardiography / Q000379:methods; D005260:Female; D006333:Heart Failure / Q000503:physiopathology / Q000628:therapy; D006352:Heart Ventricles / Q000503:physiopathology*; D006801:Humans; D008297:Male; D055414:Myocardial Perfusion Imaging / Q000379:methods; D013223:Statistics as Topic; D014055:Tomography, Emission-Computed / Q000379:methods; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000175:diagnosis / Q000503:physiopathology; D054088:Ventricular Septum / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology
Cardiac resynchronization therapy; Emission computed tomography; Heart failure; Redistribution; Right ventricular apical pacing