Non invasive hemodynamic monitorization for AV interval optimization in patients with ventricular resynchronization therapy.
OBJECTIVE
In patients (pts) with dilated cardiomyopathy and intraventricular conduction disturbances, resynchronization therapy improves cardiac function and functional capacity. Determination of the optimal AV interval is essential to optimize the therapy results and various methods have been used in daily practice to obtain such an interval. The aim of this work is to assess optimal AV determined by impedance cardiography and compare it to the interval previously obtained by transmitral flow Doppler echocardiography.


METHODS
Seven pts were evaluated, five men, mean age of 61 +/- 10 years, with dilated cardiomyopathy, intra-ventricular conduction disturbances and heart failure, New York Heart Association functional class III or IV. Four pts had ischemic cardiomyopathy and three idiopathic. All pts had an implanted cardioverter-defibrillator with cardiac resynchronization.


METHODS
The optimal AV delay was estimated by transmitral flow pulsed Doppler using the method previously described by Ritter. Subsequently, cardiac output (CO) was determined by impedance cardiography. CO was estimated for different AV delays, beginning with 80 ms until occurrence of fusion QRS. The optimal AV delay was defined as the value corresponding to the highest measured CO. The ideal AV interval was compared between the two methods used.


RESULTS
The AV delay determined by echocardiography varied between 120 and 170 ms (134 +/- 17 ms). The optimum AV delay based on CO estimation varied between 110 and 190 ms (137 +/- 26 ms). There was a correlation between the delays determined by the two methods (r = 0.844; p = 0.017).


CONCLUSIONS
In pts undergoing ventricular resynchronization therapy, AV delay optimization based on CO determined by impedance cardiography is comparable to that measured by transmitral flow pulsed Doppler. However, impedance cardiography seems a more objective and simpler technique.
Santos
José Ferreira
JF
Serviço de Cardiologia do Hospital São Bernardo, Setúbal. jferreirasantos@netvisão.pt
Parreira
Leonor
L
Madeira
João
J
Fonseca
Nuno
N
Soares
Luís Neves
LN
Inês
Lopes
L
D000368:Aged; D001145:Arrhythmias, Cardiac / Q000150:complications; D002307:Cardiography, Impedance; D002311:Cardiomyopathy, Dilated / Q000150:complications / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015150:Echocardiography, Doppler; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D018754:Ventricular Dysfunction / Q000150:complications