1. Acute effects of RV pacing on cardiac hemodynamics and transvalvular impedance M.Taborsky, M.Fedorco, T.Skala, E.Kocianova, D.Richter, D.Marek, J.Ostransky Dept. of Internal Medicine - Cardiology, University Hospital, Olomouc, Czech Republic

2. Chronic right-ventricular apical pacing can affect the cardiac function  Electrical and mechanical desynchronization  Reduced myocardial performance with increased stress  Increased risk of AF and CHF

3. Open questions Does right-ventricular pacing (RVP) also produce acute effects on cardiac hemodynamics ? Can the RVP long-term consequences be predicted from the acute effects ? What are the most sensitive indicators of pacing- induced hemodynamic troubles ? Is the hemodynamic impact of RVP dependent on the pacing site ? Can the risk be reduced by individual pacing site selection ?

4. Study design  During dual-chamber implantation procedures for SSS or AVB, the ventricular lead was sequentially positioned in RV apex and mid-septum. Measurements:  left-ventricular pressure and dP/dt;  systolic and diastolic hemodynamic parameters assessed by 2D echocardiography and by echo and tissue Doppler;  Transvalvular impedance (TVI). Recording conditions:  intrinsic activity; AAI pacing at 90 bpm;  VDD and DDD pacing at 90 bpm with apical and septal stimulation.

5. AEGM VEGM ECG I LVP dP/dt TVI (Vring) 150 mmHg 2000 mmHg/s 50 Ohm Set of tracings

6. Paired Student t-test (n=29) The increase in QRS duration induced by ventricular pacing depends on the pacing site

7. Paired Student t-test (n=29) The increase in QRS duration induced by ventricular pacing depends on the pacing site

8. AEGM VEGM ECG II LVP 2:1 AVB QRS 110 ms VDD in RVA QRS 180 ms VDD in RVS QRS 120 ms RV septal stimulation improves QRS axis and duration with respect to apical pacing

9. IAVC VDD; 80 ms AV delay ECG I LVP dP/dt dP/dt max is reduced by RV pacing at either site

10. Septal pacing was better Apical pacing was better y = x Was there individual preference for a specific pacing site?

11. ECG II LVP dP/dt IAVCVDD; 80 ms AV delay LVP decrease is affected

12. LVP sys is not modified by VDD pacing LVP dias is significantly increased

13. Rate increase to 90 bpm produced by:  AAI pacing  DDD pacing (80 ms AV delay) in RV apex  DDD pacing (80 ms AV delay) in mid- septum

14. Effects of cardiac rate on dP/dt max and LVP sys

15. Effects of RV pacing on echocardiographic systolic parameters

16. Echocardiographic diastolic parameters

17. RV lead in mid septum AAI 60 bpm DDD 60 bpm TVI VEGM AEGM ECG II LVP 60 Ohm 100 mmHg TVI In some cases, RV pacing induced virtually no change in TVI waveform

18. AEGM VEGM ECG I TVI Sinus rhythm VDD EDTVI 421 Ohm ESTVI 460 Ohm EDTVI 434 Ohm ESTVI 461 Ohm RV lead in mid septum TVI In some cases, RV pacing affected TVI amplitude

19. transition from AAI to VDD AEGM VEGM I TVI 60 Ohm LVP RV lead in apex In other cases, RV pacing induced morphological changes in TVI

20. TVI was measured in both RV apex and septum in 32 patients. The success frequency was not significantly different at the two recording sites. TVI recording can be performed in RV septum as well as in apex

21. The frequency of substantial morphological alterations was much higher in RV apex than septum Right ventricular pacing affects TVI properties

22. OK = no morphological alteration and amplitude  75% With intrinsic rhythm, the TVI signal was appropriate at both RV apex and septum in 25 cases. The frequency of cases featuring unaltered TVI waveform with VDD pacing was significantly higher in RV septum than apex.

23. OK = no morphological alteration and amplitude  75% DDD was tested in 18 cases featuring appropriate TVI at both RV apex and septum with intrinsic rhythm. The frequency of cases with unaltered TVI waveform in 90 bpm DDD was significantly higher in RV septum than apex.

24. CONCLUSIONS  Right ventricular pacing applied in apex or mid-septum acutely affected both systolic and diastolic function.  The QRS duration was longer and the proportion of cases featuring deep alterations in TVI waveform was higher with apical than septal pacing.  Left ventricular pressure and echocardiographic parameters were similarly affected by RV pacing applied at either site.  Septal stimulation might produce a shorter electrical interventricular delay and milder mechanical modifications in RV with respect to apical pacing, while LV hemodynamic indices dependent on the intraventricular synchronization seem to be less sensitive to the position of the pacing lead.