Study On Evaluating Cardiac Function And Synchronism In The Patients With RV Pacing At Different Sites By Real-time Three-dimensional Echocardiography

Objective:To evaluate cardiac function and synchronism in patients with right ventricular apical pacing(RVAP) or right ventricular non-apical pacing(RVNAP) and normal left ventricular eject fraction(LVEF) by real-time three-dimensional echocardiography(RT-3DE) Methods:A total of 103 consecutive patients(53 men and 50 women, age 53-85 years) who had bradycardia and normal cardiac function(LVEF≥50%) were enrolled. They were hospitalized for implantation of permanent dual chamber antibradycardiac pacemaker in cardiology department of the Second Hospital of Tianjin Medical University during the year 2013-2014. According to the right ventricular lead position judged by RT-3DE, all patients may be classified into two groups: RVAP(patients with right ventricular apical lead position) group(n=50) and RVNAP(patients with right ventricular non-apical lead position) group(n=53). Recording the basic characteristic including height, weight, history of hypertension and diabetes, smoking, drinking and medication history.All patients had pacemaker for any bradycardia with anticipated RV pacing of more than 90%, and the cumulative percentage of right ventricular pacing was also more than 90% at follow-up. Patients with an indication for an implantable cardioverter defibrillator or cardiac resynchronization therapy were exclude. Patients with atrial fibrillation, bundle branch block, serious valvular heart disease, hypertrophic cardiomyopathy, dilated cardiomypathy, congenital heart disease, history of myocardial infarction, chronic obstructive pulmonary disease, disease that affect cardiac structure and function such as hepatic and renal insufficiency were all exclude.The pacing leads were inserted into right heart via the subclavian vein under the leading of chest X-ray. Then operator judged the right ventricular pacing lead according to chest X-ray and ECG.Echocardiographic examinations were performed separately on admission before pacing, at 1 week and 1 year follow-up after pacing by the same experienced physician by using a Fillips i E33(Bothell,Washington, USA) ultrasound scanner with a 1-5 MHz-phased array and 3V probe.The subjects were examined in condition of right ventricular pacing. Regularly ultrasonography was taken to measure LVEF-2D, left atrial diameter, interventricular septal thickness, left ventricular posterior wall thickness, right ventricular diameter, left ventricular end-diastolic diameter and left ventricular end-systolic diameter. In addition, transmitral blood flow Doppler signals were used to measure peak early(E) and late(A) diastolic velocities and the ratio(E/A). E/e is the ratio of the peak velocity of early diastolic LV filling and the speed of mitral ring. Its normal value is less than 8 which refers to normal LV filling pressure, border value(gray zone) is 8-15, diastolic dysfunction is ouer 15 and points to increased LV filling pressure. E/e and myocardial performance index(MPI) was measured by tissue pulse Doppler. Images of the parasternal long axis plane, apical four-chamber, apical two-chamber were acquisition. Activating full volume imaging in apical four-chamber. All the recordings lasted at least five cardiac cycles and were digitally stored for offline analysis. Entered into QLAB 3DQ advance software analysis system, 17 segmental volume-time curves(VTCs) and the “bull’s eye plot” were acquired to measure systolic dyssynchrony index including Tmsv-16-SD%, Tmsv-base-SD%, Tmsv-midSD%, Tmsv-apical-SD%, Tmsv-anterior-SD%, Tmsv-septal-SD%, Tmsv-inferiorSD%, Tmsv-lateral-SD% and diastolic function index(diastolic peak filling rate, PFR) and left atrial function index including left atrial active ejection fraction, left atrial passive ejection fraction, left atrial volume index. All the measurements were repeated three times and taken the average value to reducing the error. Finally, all data was statistically analyzed and processed. Results: 1. There were no significant statistical differences in basic clinical characteristics including sex, age, body mass index(BMI), hypertension, diabetes, smoking, drinking and medication history between RVAP group and RVNAP group(P>0.05) neither in echocardiographic index measured by conventional echocardiography or RT-3DE between the two groups(P>0.05). 2. The results of the right ventricular lead position judgement using CXR and RT-3DE respectively were basically identical,the rate of nonidentical was 18.4%. Certain differences existed, especially in RVNAP patients, between two judgement methods. 3. After 1 week of pacemaker stimulation, QRS duration in both RVAP group and RVNAP group increased(P>0.05). Measurements including LAD, LVD, RVD, IVS, LVPW, LVEF-2D, E/A, E/e, LVEF-3D, PFR, LAVI, LAAEF, LAPEF remained the same as pre-pacing both intra-group RVAP and intra-group RVNAP. 4. After 1 year’s pacemaker stimulation, measurements including LAD, IVS, LVPW, MPI2, LAAEF, E/e, SDI increased and LVEF-3D, LAVI, PFR decreased compared to pre-pacing intra-group RVAP(P<0.05), and LVD, LVS, RVD, LVEF-2D, E/A, LAPEF MPI3 remained the same intra-group RVAP(P>0.05). Measures including LAD, IVS, E/e, SDI increased, and PFR decreased compared to pre-pacing intra-group RVNAP(P<0.05), and LVD, LVS, RVD, LVEF-2D, LVEF-3D, E/A, MPI2, MPI3, LAPEF, LAPEF remained the same intra-group RVNAP(P>0.05). 5. Compared with RVAP group, the change value ΔQRS, ΔLAD, ΔLAVI were lower in RVNAP group(P<0.05), and no statistical difference in ΔIVS, ΔE/e and ΔPFR(P>0.05). 6. Compared with RVAP group after 1 year of pacemaker stimulation, SDI in 16-segment, inferior, septum, apical of RVNAP group is smaller(P<0.05), and no statistical difference in anterior, basement and lateral(P>0.05). 7. After 1 year’s pacemaker stimulation, the systolic peak filling rate were positively correlated with 16-segment SDI(r=-0.201,P=0.041). Conclusions: 1. Long-term pacemaker stimulation leads to progression of cardiac dysfunction in patients with normal prepacing LVEF, effects on the right ventricle may be relatively smaller. 2. There is no significant difference between RVAP group and RVNAP group in diastolic dysfunction. Long-term pacemaker stimulation leads to progression of left atrial dysfunction in both RVAP group and RVNAP group, the former is more obvious. 3. There is a positive relationship between the systolic peak filling rate and SDI. 4. RVNAP can be considered as the first choice for those patients who needed to be implanted permanent pacemaker. Meanwhile, optimal RV pacing sites are alwas comprehensively considered combining with the right ventricular structure, local sensing and pacing threshold. 5. RT-3DE may be one of the best choices to evaluate post-pacing patients’ cardiac function and RV pacing lead position.