European Journal of Echocardiography Advance Access originally published online on June 10, 2009
European Journal of Echocardiography 2009 10(6):776-783; doi:10.1093/ejechocard/jep069
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Left ventricular dyssynchrony from right ventricular pacing depends on intraventricular conduction pattern in intrinsic rhythm
1 Department of Cardiology, Klinikum Coburg, Ketschendorfer Str. 33, DE-96450 Coburg, Germany
2 Division of Cardiology, Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
3 Department of Cardiology, Klinik Augustinum, München, Germany
Received 28 February 2009; accepted after revision 9 May 2009; online publish-ahead-of-print 10 June 2009.
* Corresponding author. Tel: +49 9561 2233223; fax: +49 9561 226490. E-mail address: mschmidtco{at}arcor.de
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Abstract |
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Aims: Right ventricular pacing (RVP) prolongs ventricular activation and may induce mechanical dyssynchrony. We hypothesized that the severity of RVP-associated ventricular mechanical dyssynchrony may depend on the intrinsic intraventricular conduction pattern.
Methods and results: Sixty-five patients with a single- or dual-chamber RV pacemaker were included. Forty-seven patients with ejection fraction (EF) 
35%, 17 with no bundle branch block (BBB), 16 with right bundle branch block (RBBB), and 14 with left bundle branch block (LBBB). Eighteen patients with EF > 35% and no BBB served as a control group. Echocardiographic dyssynchrony parameters [aortic pre-ejection delay (AoPEP), interventricular mechanical delay, delayed posterior left ventricular wall motion, and septal-to-posterior wall motion delay (SPWMD)] were evaluated in all patients with and without RVP. No dyssynchrony was found in patients with no BBB, RBBB, and in the control group, whereas LBBB patients showed significant dyssynchrony in AoPEP and SPWMD. RVP had a significant negative impact on all dyssynchrony parameters in patients with no BBB or LBBB. RVP induced significantly less severe dyssynchrony in RBBB patients. With RVP 100, 94, 56 and 16% of patients with LBBB, without BBB, RBBB, and from the control group, respectively, fulfilled the CARE-HF criteria for ventricular dyssynchrony.
Conclusion: RVP worsens mechanical ventricular dyssynchrony in patients with reduced EF. These effects are most pronounced in patients with either normal QRS width or LBBB during intrinsic rhythm. In contrast, patients with an RBBB during intrinsic rhythm without RVP evidenced a better preserved haemodynamic function and mechanical synchrony with RVP, despite a comparable extent of pacing-induced QRS prolongation.
Keywords: Left bundle branch block; Right bundle branch block; Mechanical ventricular dyssynchrony