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eComment: Biventricular pacing in cardiac surgery – potential role for non-invasive cardiac output monitoring and nt-pro-BNP determination

Plastic, Hand and Reconstructive Surgery, Hannover Medical School, Hannover 30625, Germany

Impact of pacing modality and biventricular pacing on cardiac output and coronary conduit flow in the post-cardiotomy patient

I appreciate the report of Dr. Healy and coworkers from Ireland studying the impact of pacing modality and biventricular pacing on cardiac output and coronary conduit flow in the post-cardiotomy patient [1]. DDD pacing was associated with the best cardiac output determined by arterial pulse waveform analysis with the Vigileo system (FloTrac Edward's Lifescience, Irvine, CA, USA). The authors found that in their patient cohort biventricular pacing was not associated with improved cardiac output or improved coronary conduit flow. Only a limited number of patients with only minor impairment of cardiac pump function were involved in the study, which might at least in part explain the aforementioned results.

A recent study supports this finding [2]. Twenty-one consecutive patients with an ejection fraction <35% underwent hemodynamic evaluation (continuous pressures and thermodilution) 3, 6, and 18 h post-CABG and biatrial (AA), biatrial-right ventricular (AAV), and biatrial- biventricular (AAVV) pacing were compared. Cardiac output (CO) was determined as an average of three measurements by thermodilution over 6 min using 10 ml ice-cold water for injection. The authors found that biventricular pacing improves CI in patients with poor EF following cardiac surgery in the absence of preoperative atrioventricular- or interventricular conduction block. This benefit decreases with time after surgery as the QRS width returns to preoperative values. Four-chamber pacing did not confer additional benefit as compared to biventricular pacing in this series. Biventricular pacing should be considered as an adjunct in patients with critically low EF undergoing cardiac surgery.

In addition, both the mode of cardiac output determination as well as the mode of coronary conduit flow might have influenced their findings, which is not addressed in detail in the paper. Ultrasonic cardiac output monitoring (USCOM, Sydney, Australia) has been reported to be a simple, accurate and fast non-invasive method for the optimization of atrío-ventricular interval (AVI) in cardiac resynchronization therapy (CRT) [3]. Currently, no such study exists to the best of my knowledge for the aforementioned Vigileo invasive system.

Last, it would be interesting how cardiac markers such as nt-pro-BNP might be influenced by the mode of pacing in future studies. A close relationship between non-invasive cardiac output determined by ultrasonic cardiac output monitoring (USCOM) and nt-pro-BNP levels in cardiotoxicity monitoring has been reported [4]. The Cardiac Resynchronization-Heart Failure (CARE-HF) study demonstrated that cardiac resynchronization therapy (CRT) could reduce morbidity and mortality and improve cardiac function in patients with moderate or severe heart failure secondary to left ventricular systolic dysfunction. Nt-pro-BNP reduction has been observed following CRT in responders [5]. Thus, nt-pro-BNP monitoring might be a simple and appropriate method to study the effects of different pacing modes such as CRT or postoperative biventricular or quadruple pacing in cardiac surgery patients.

	References

Top References

 

1. Healy DG, Hargrove M, Doddakulla K, Hinchion J, O'Donnell A, Aherne T. Impact of pacing modality and biventricular pacing on cardiac output and coronary conduit flow in the post-cardiotomy patient. Interact Cardiovasc Thorac Surg 2008;7:805–808.[Abstract/Free Full Text]
2. Pichlmaier M, Bagaev E, Lichtenberg A, Teebken O, Klein G, Niehaus M, Haverich A. Four-chamber pacing in patients with poor ejection fraction but normal QRS durations undergoing open heart surgery. Pacing Clin Electrophysiol 2008;31:184–191.[Medline]
3. Siu CW, Tse HF, Lee K, Chan HW, Chen WH, Yung C, Lee S, Lau CP. Cardiac resynchronization therapy optimization by ultrasonic cardiacoutput monitoring (USCOM) device. Pacing Clin Electrophysiol 2007;30:50–55.[Medline]
4. Knobloch K, Tepe J, Rossner D, Lichtinghagen R, Luck HJ, Busch KH, Vogt PM. Combined nt-pro-BNP and CW-Doppler ultrasound cardiac output monitoring (USCOM) in epirubicin and liposomal doxorubicin therapy. Int J Cardiol 2007 Aug 15.
5. Fruhwald FM, Fahrleitner-Pammer A, Berger R, Leyva F, Freemantle N, Erdmann E, Gras D, Kappenberger L, Tavazzi L, Daubert JC, Cleland JG. Early and sustained effects of cardiac resynchronization therapy on n-terminal pro-B-type natriuretic peptide in patients with moderate to severe heart failure and cardiac dyssynchrony. Eur Heart J 2007;28:1592–1597.[Abstract/Free Full Text]

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