Right Atrial Pacing Impairs Cardiac Function During Resynchronization Therapy
Acute Effects of DDD Pacing Compared to VDD Pacing
Alain Bernheim, MD,
Peter Ammann, MD,
Christian Sticherling, MD,
Peter Burger, MD,
Beat Schaer, MD,
Hans Peter Brunner-La Rocca, MD,
Jens Eckstein, MD,
Stephanie Kiencke, MD,
Christoph Kaiser, MD,
Andre Linka, MD,
Peter Buser, MD,
Matthias Pfisterer, MD and
Stefan Osswald, MD*
Division of Cardiology, University Hospital, Basel, Switzerland.
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Figure 1 Depicts the time periods of the entire cardiac cycle (electrocardiogram [ECG] and Doppler flow) in DDD pacing mode (A) compared to the VDD pacing mode (B). Note the prolongation of the mitral inflow time (E + A dur) secondary to the shorter isovolumic contraction time (IVT), isovolumic relaxation time (IVRT), and aortic ejection time (ET) in the VDD as compared to the DDD pacing mode. Data of time intervals are presented as the mean value (ms) ± SD. *p < 0.01 VDD versus DDD. ECG labeling: P = P-wave; R = R-wave; T = T-wave. Doppler inflow labeling: A = A-wave (late transmitral inflow during left atrial contraction); E = E-wave (early transmitral flow).
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Figure 2 Comparison of the left ventricular (LV) filling time achieved with DDD versus VDD pacing. The graphically presented data are mean values ± SD. *p = 0.0001 between the two groups.
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Figure 3 Pulsed-wave Doppler echocardiographic recordings of the left ventricular inflow measured at the tips between the mitral leaflets. The cycle length during DDD pacing was mathematically adjusted to the cycle length of the tracing in VDD mode (A). Note the complete fusion of early diastolic and atrial filling observed in the DDD mode (A), whereas in the VDD mode the peak of the E- and the A-wave are still clearly separated (B). These Doppler tracings are representative for the findings observed in five (29%) patients.
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Figure 4 (A and B) Show pulsed-wave Doppler recordings of the left ventricular inflow mathematically adjusted for the difference in heart rate between the two pacing modes. Note the significantly prolonged mitral inflow time and the more physiological E and A traces in the VDD mode (B). In the DDD mode, there is incomplete fusion between E-wave (passive mitral inflow) and A-wave (active atrial filling). Note that there is a beginning cutoff of the A-wave in the DDD mode, although there is a lower degree of left ventricular synchronization compared to VDD pacing as suggested by the mitral flow impairment (see text).
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