Rick Schreurs

46 Chapter 3 LVEDV ( Figure 4B ), and LV inflow pattern ( Figure 4C ). Most separated E- and A-waves and least diastolic MR occurred during synchronous pacing ( Figure 4C ). Table 1. Hemodynamic data of AV-optimization in porcine hearts during BiV pacing AV-delay 50ms 100ms 150ms 200ms 250ms 300ms (BL) PQ interval (ms) 53±2* 102±2* 151±1* 202±2* 254±2* 304±1 MAP (mmHg) 79±25* 87±23 91±24* 91±23* 88±25 84±24 Cardiac output aorta (L/min) 3.0±0.3 3.3±0.3 3.4±0.4 3.4±0.4 3.2±0.3 3.1±0.3 Stroke work (mmHg*ml) 3732±1146 4316±1012 4437±1042 4379±1123 4169±1239 3828±1266 LV dP/dt max (mmHg/s) 1225±311* 1297±282 1274±259 1308±282 1275±295 1265±311 LVSP (mmHg) 95±21* 102±20 106±22* 105±21* 103±22 99±21 LV EDP (mmHg) 7.0±2.8 8.7±2.6 9.5±2.1* 7.8±2.4 7.4±2.9* 6.9±3.0 LAP mean (mmHg) 8.4±2.4* 7.8±2.4* 6.8±2.3 6.6±2.2 6.6±2.4 6.5±2.2 LV EDV (mL) 78±39 83±39 90±36* 87±36* 83±39* 80±40 Diastolic MR (mL/beat) 0.3±0.5 2.5±1.9 4.4±2.9 4.5±3.3 4.3±3.3 6.1±4.0 Forward flow (mL/beat) 50±9 53±8 53±6 53±6 51±7 51±8 MR fraction (%) 0.9±1.5 5.2±4 9.5±6.2 10±7.2 10±7.7 15±10.2 Results are presented as mean±SD (n=7). BL: baseline, MAP: mean arterial pressure, LV: left ventricular, LVSP: LV systolic pressure, EDP: end diastolic pressure, LAP mean : mean left atrial pressure, EDV: end diastolic volume, ESV: end systolic volume, MR: mitral regurgitation. * indicates P<0.05 compared to 300ms (BL) Patient study Table 2 shows the baseline patient characteristics. The study cohort consisted of patients with moderate to severe heart failure (NYHA II or III), mean LVEF of 29±6%, mean PR- interval of 261±32ms, QRS duration of 123±19ms and a mix of ischemic and dilated cardiomyopathy. Similar to the computer simulations and animal studies ( Figure 2 and 4 ), patients showed the characteristic pattern of E-A wave fusion and diastolic MR at baseline ( Figure 5A ). During BiV pacing, a clear separation of the E- and A-waves was seen at AV-delays of 50% and 75% of intrinsic PR-interval, while truncation of the A-wave occurred at shorter AV-delay (25% of intrinsic PR-interval). Restoration of AV-coupling by BiV pacing at an AV-delay of 50% of intrinsic PR-interval (137±30ms) resulted in a significant increase of forward mitral flow (on average +8mL/beat) and reduction of MR fraction (on average -12 %-point, figure 5B and C and table 2 ).