Author + information
- John E. Madias, MD* ()
- ↵*Division of Cardiology, Elmhurst Hospital Center, 79-01 Broadway, Elmhurst, New York 11373
I was delighted to read the report by Khoury et al. (1) in the March 24, 2009, issue of the Journal, related to an area I have been interested in since 1998, namely, using electrocardiography in monitoring the edematous state of patients with varying pathologic features, including congestive heart failure (CHF) (2). The authors evaluated the response of 6 bioelectric impedance signals in 15 dogs with CHF due to cardiomyopathy imparted by chronic rapid right ventricular pacing by using a variety of electrode configurations of a cardiac resynchronization system that they had implanted. The key finding of this study is that the left ventricular ring-to-can vector represented the electrode configuration with the fastest and largest change in impedance and had the best correlation with the rise in the left ventricular end-diastolic dimension and left atrial pressure noted with the worsening of CHF. The clinical implications here are that a left ventricular lead, in contrast to a right ventricular lead currently used, has advantages in the ambulatory monitoring of CHF. Particularly worrisome is the previously described moderate rate of false positive results of decreasing impedance, measured via the right ventricular lead, in patients who did not have hemodynamic deterioration leading to lung congestion. What I do not understand is why, despite this, the authors urge the use of measurements and monitoring of impedance through multiple electrode configurations, instead of only using the left ring-to-can electrode, which they found themselves to be superior to any of the other 5 electrode configurations. What is the objective of such a recommendation? Do they imply that their results need confirmation by other animal investigations, or that their findings require corroboration in human studies, or that they still suspect that the other 5 electrode configurations may have some special role to play? And if the latter is the case, what role?
- American College of Cardiology Foundation