Diagnosis of sleep-related breathing disorders by visual analysis of transthoracic impedance signals in pacemakers.
BACKGROUND
Minute ventilation sensors of cardiac pacemakers measure ventilation by means of transthoracic impedance changes between the pacemaker case and the electrode tip. We investigated whether this technique might detect sleep-related breathing disorders.


RESULTS
In 22 patients, analog waveforms of the transthoracic impedance signal measured by the pacemaker minute ventilation sensor over the course of a night were visualized, scored for apnea/hypopnea events, and compared with simultaneous polysomnography. Analysis of transthoracic impedance signals correctly identified the presence or absence of moderate to severe sleep apnea (apnea/hypopnea index, AHI >20 h(-1)) in all patients (receiver operating characteristics, ROC=1.0). The ROC for AHI scores of > or =5 h(-1) and > or =10 h(-1) showed an area under the curve of 0.95, P<0.005, and 0.97, P<0.0001, respectively. Accuracy over time assessed by comparing events per 5-minute epochs was high (Cronbach alpha reliability coefficient, 0.85; intraclass correlation, 0.73). Event-by-event comparison within +/-15 seconds revealed agreement in 81% (kappa, 0.77; P<0.001).


CONCLUSIONS
Detection of apnea/hypopnea events by pacemaker minute ventilation sensors is feasible and accurate compared with laboratory polysomnography. This technique might be useful to screen and monitor sleep-related breathing disorders in pacemaker patients.
Scharf
Christoph
C
Cardiovascular Center, University Hospital Zurich, Department of Internal Medicine, Division of Cardiology and Pneumology, Rämistrasse 100, CH-8091 Zürich, Switzerland. christoph.scharf@usz.ch
Cho
Yong K
YK
Bloch
Konrad E
KE
Brunckhorst
Corinna
C
Duru
Firat
F
Balaban
Kryzstof
K
Foldvary
Nancy
N
Liu
Lynn
L
Burgess
Richard C
RC
Candinas
Reto
R
Wilkoff
Bruce L
BL
D000368:Aged; D002307:Cardiography, Impedance; D005260:Female; D006801:Humans; D008297:Male; D010138:Pacemaker, Artificial; D017286:Polysomnography; D012891:Sleep Apnea Syndromes / Q000175:diagnosis*; D014785:Vision, Ocular