title: Intrathoracic impedance and ultrasound lung comets in heart failure deterioration monitoring.
abstract: OBJECTIVE
  Echographic examination of the lung surface may reveal multiple ultrasound lung comets (ULCs) originating from water-thickened interlobular septa. These images were demonstrated to be useful for noninvasive assessment of interstitial pulmonary edema. Similarly, the correlation between implantable defibrillator-measured intrathoracic impedance and pulmonary capillary wedge pressure (PCWP) was demonstrated in heart failure (HF) patients. The aims of this analysis were to assess the agreement between defibrillator-detected impedance decrease and the presence of ULCs, as well as to compare the performance of the impedance-detection algorithm and the ULCs assessment in predicting HF worsening.
  
  
  RESULTS
  We studied 23 HF patients implanted with a defibrillator capable of intrathoracic impedance measurement and alerting for fluid accumulation diagnosis. At regular follow-up and at visits for HF decompensation or device alert, clinical status was assessed, chest ultrasound was performed, and PCWP was noninvasively estimated with Doppler echocardiography. During 23 ± 11 months of follow-up, 45 paired assessments of defibrillator-measured intrathoracic impedance and ULCs were performed. The number of ULCs resulted significantly correlated to the paired PCWP estimations (r = 0.917, P < 0.001) and to the impedance fluid index (r = 0.669, P < 0.001). During follow-up, 12 episodes of HF decompensation were reported in 12 patients. The impedance alert detected clinical HF deterioration with 92% sensitivity and 69% positive predictive value. The presence of ≥5 ULCs showed 83% sensitivity and 91% positive predictive value.
  
  
  CONCLUSIONS
  These data demonstrate the correlation between intrathoracic impedance and the number of ULCs at chest ultrasound, and a good agreement between the defibrillator warning for fluid index and the detection of multiple ULCs.
authors.affiliation: Division of Cardiology, Santa Maria del Carmine Hospital, Rovereto (TN), Italy. mainesdrmax@hotmail.com
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Maines
authors.forename: Domenico
authors.initials: D
authors.lastname: Catanzariti
authors.forename: Carlo
authors.initials: C
authors.lastname: Angheben
authors.forename: Sergio
authors.initials: S
authors.lastname: Valsecchi
authors.forename: Jennifer
authors.initials: J
authors.lastname: Comisso
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Vergara
mesh_terms: D000368:Aged; D000465:Algorithms; D002307:Cardiography, Impedance / Q000295:instrumentation / Q000379:methods; D017147:Defibrillators, Implantable; D015150:Echocardiography, Doppler / Q000379:methods; D015633:Extravascular Lung Water / Q000000981:diagnostic imaging*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000000981:diagnostic imaging; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011654:Pulmonary Edema / Q000000981:diagnostic imaging*; D011669:Pulmonary Wedge Pressure; D012680:Sensitivity and Specificity