Europace Advance Access originally published online on November 11, 2009
Europace 2009 11(12):1666-1674; doi:10.1093/europace/eup358
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Pacing and CRT
Non-invasive cardiac output measurements based on bioreactance for optimization of atrio- and interventricular delays
1 Addenbrooke's Hospital, Level 6, ACCI Building, Box 110, Hills Road, Cambridge CB2 2QQ, UK; 2 Papworth Hospital, Papworth Everard, Cambridge CB23 8RE, UK
Aims: Non-invasive cardiac output monitoring (NICOM) based on bio-reactance offers a portable method to assess ventricular function. Optimization of cardiac resynchronization therapy (CRT) by echocardiography is labour-intensive. We compared the ability of NICOM and echocardiography to facilitate optimum CRT device programming.
Methods and results: Forty-seven patients in sinus rhythm were evaluated within 14 days of CRT implantation. The atrio- (AV) and interventricular (VV) delay intervals were incrementally adjusted and at each setting, NICOM and echocardiographic data were recorded. Left ventricular (LV) volumes and function were assessed by echocardiography at baseline and 3 months. Response to CRT was defined as a reduction in LV end-systolic volume (LVESV) by >15%. In all patients, cardiac output (CO) increased significantly at optimized settings compared with baseline (5.66 ± 1.4 vs. 4.35 ± 1.1 L/min, P < 0.001). A 20% increase in acute CO following CRT predicted LVESV reduction of >15% with a sensitivity of 81% and specificity of 92% (AUC 0.86). The optimum AV delay determined by NICOM was confirmed by echocardiography in 40 of 47 patients (85%, r = 0.89, P < 0.01) and for VV delay in 39 of 47 patients (83%, r = 0.89, P < 0.01).
Conclusion: Non-invasive cardiac output monitoring is a simple, reliable, and portable alternative to echocardiography to program CRT devices.
Key Words: Cardiac output, CRT, Optimization, Non-invasive
* Corresponding author. Tel: +44 1223 331504, Fax: +44 1223 331505, Email: dpd24{at}cam.ac.uk
Manuscript submitted 8 September 2009. Accepted after revision 15 October 2009.