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Comparison of the Effects of Right Atrial, Right Ventricular Apex and Atrioventricular Sequential Pacing on Myocardial Oxygen Consumption and Cardiac Efficiency: A Laboratory Investigation *
Author(s) -
BALLER DETLEV,
WOLPERS HANSGEORG,
ZIPFEL JOHANNES,
BRETSCHNEIDER HANSJÜRGEN,
HELLIGE GERHARD
Publication year - 1988
Publication title -
pacing and clinical electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.686
H-Index - 101
eISSN - 1540-8159
pISSN - 0147-8389
DOI - 10.1111/j.1540-8159.1988.tb05998.x
Subject(s) - medicine , cardiology , cardiac output , heart rate , hemodynamics , cardiac pacing , anesthesia , blood pressure
As the impact of cardiac pacing on myocardial energetics has not yet been established, this laboratory investigation was undertaken to evaluate the ejects of right atrial (AP), right ventricular apex (VP) and atrioventricular sequential pacing (AVP) on cardiac energetics in a closed‐chest model. Ninety‐two pacing interventions were performed in ten anesthetized mongrel dogs with normal loading conditions and contractile states. The energetic effects of pacing were assessed in terms of myocardial oxygen consumption (MVO z ), its hemodynamic determinants and cardiac effciency. Effciency was calculated as the ratio of O 2 ‐equivalent of external cardiac work to MVO 2 , using standard definitions. In the first series of experiments 36 intra‐individual comparisons were made between AP and VP at identical rates (95–210 beats/min). In the second series AVP was compared to VP in 10 intra‐individual comparisons at identical rates (109–190 beats/min). MVO 2 was lower (p < 0.001) during AP (8.30 ± 2.14 ml O 2 /min · 100 g) compared to VP (10.16 ± 3.15 ml O 2 /min · 100 g) at the same rate (158 ± 32 beats/min). Efficiency (p < 0.001) was considerably higher during AP (21.6 ± 5.7%) compared to VP (12.8 ± 5.9%). During AVP, MVO 2 (10.85 ± 1.76 ml O 2 /min · 100 g) was not significantly different from VP (10.57 ± 1.34 ml O 2 /min · 100 g) at the same rate (146 ± 25 beats/min). Hemodynamics were superior with AVP compared to VP. Efficiency was significantly higher (p < 0.01) with sequential (15.4 ± 3.9%) as compared to ventricular pacing (12.0 ± 3.2%). In conclusion, this study indicated that VP exerts disadvantageous effects on MVO 2 and cardiac effciency. AP has beneficial effects on cardiac energetics because it improves the relationship between mechanical performance of the heart and its energy requirements. AVP results in a higher efficiency than VP due to superior hemodynamics, despite MVO 2 levels comparable to those of VP. The mechanism of energy waste with right ventricular apex pacing is probably related to an asynchronous contraction in the ventricular myocardium due to a nonphysiological spread of excitation.