Rick Schreurs

90 Chapter 5 Resp3 NResp3 Resp2 Responders Non-responder dP/dt max (mmHg/s) SonR (mG) 0 1000 2000 3000 4000 dP/dtmax (mmHg/s) 0 500 1000 1500 2000 2500 SonR (mG) 0 1000 2000 3000 4000 dP/dtmax (mmHg/s) 0 1000 2000 3000 4000 LV dP/dtmax RV dP/dtmax 0 500 1000 1500 2000 2500 SonR (mG) 0 500 1000 1500 2000 2500 RA SonR1 RV SonR1 Time Time Time LV dP/dt max RV dP/dt max RA SonR1 RV SonR1 Figure 1. Dobutamine stress test in 3 animals. Concentrations of dobutamine infusion were gradually increased and subsequently decreased and stopped. The animals were in sinus rhythm, heart rate slightly decreases at maximal infusion rates. The upper panels present the changes in LV and RV dP/dt max . In the lower panels the accompanied increases in RA and RV SonR1 are shown. Data are presented as moving average over 5 beats. The effect of contractility on SonR1 Dobutamine stress tests were performed in 3 animals ( Figure 1 ) to test the effect of contractility on SonR1 amplitude. Dobutamine reversibly increased cardiac contractility (LV and RV dP/dt max ) by a factor 2-3. RA and RV SonR1 closely followed the changes in dP/ dt max and also increased by a factor 2-3. Over the entire range of values strong correlations between LV and RV dP/dt max and RA and RV SonR1 were observed ( Table 2 ); the correlation of SonR1 with RV dP/dt max being slightly better. Table 2. Correlation (R 2 ) between LVandRVdP/dt max andRAandRVSonR1 during dobutamine stress test NResp1 Resp2 Resp3 Mean±SEM RA SonR1 LV dP/dt max 0.93 0.72 0.88 0.84±0.06 RV dP/dt max 0.95 0.83 0.89 0.89±0.04 RV SonR1 LV dP/dt max 0.95 0.71 0.73 0.80±0.08 RV dP/dt max 0.96 0.82 0.70 0.83±0.07 RA: right atrium, LV: left ventricle, RV: right ventricle.