Daily shock impedance measured by implantable cardioverter defibrillator is useful in the management of congestive heart failure.
BACKGROUND
Clinical data suggest that changes in intrathoracic impedance and fluid accumulation in the lung are inversely related.


RESULTS
Daily shock impedance (S-IMP) was evaluated in 29 patients in whom a Ventak Prizm 2 was implanted (61+/-14 years old). The mean follow-up period was 45+/-18 weeks, during which 6 patients had episodes of decompensated heart failure (DHF group) and the others did not (NHF group). There was no significant difference between the DHF group and NHF group in the mean value of the S-IMP (46.4 +/-3.3 vs 45.4+/-5.4 Omega). The range of S-IMP in individual patients in the DHF group was significantly greater than that in the NHF group (13.8+/-0.38 vs 7.0+/-3.1 Omega, p<0.0001). Mean weekly change of S-IMP in individual patients in the DHF group was significantly greater than that in the NHF group (1.583+/-0.630 vs 1.092+/-0.361 Omega, p<0.0176). When the cut-off value was set at >1.242 Omega, sensitivity was 100% and specificity was 69.6% for a diagnosis of DHF. There was a significant negative correlation between the percent increases in brain natriuretic peptide (BNP) and S-IMP (correlation coefficient: -0.775 p<0.0001) in the DHF group. There was an inverse relation between BNP and S-IMP.


CONCLUSIONS
Measurement of shock impedance may be useful in the management of congestive heart failure.
Matsushita
Kohei
K
Department of Cardiology, Yokohama City University Hospital, Yokohama 236-0004, Japan. koheimat@ya2.so-net.ne.jp
Ishikawa
Toshiyuki
T
Sumita
Shinichi
S
Kobayashi
Tsukasa
T
Ogawa
Hideyuki
H
Inoue
Noriko
N
Matsumoto
Katsumi
K
Taima
Minoru
M
Nakazawa
Ichirou
I
Sugano
Teruyasu
T
Ishigami
Tomoaki
T
Uchino
Kazuaki
K
Umemura
Satoshi
S
D000368:Aged; D002307:Cardiography, Impedance / Q000379:methods / Q000706:statistics & numerical data; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data; D005260:Female; D006333:Heart Failure / Q000097:blood / Q000503:physiopathology* / Q000628:therapy*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood; D011654:Pulmonary Edema / Q000503:physiopathology; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D020097:Natriuretic Peptide, Brain