ABSTRACT
BACKGROUND: Specific respiratory patterns and periodic breathing have been associated with heart failure. Less is known regarding changes in tidal volume (TV) and minute ventilation (MV) as a result of early heart failure (HF) decompensation. METHODS AND RESULTS: Twelve adult Yucatan minipigs were implanted with a biventricular pacemaker and a left ventricular pressure sensor. HF was induced using high-rate pacing at 240 paces per minute for 2-4 weeks, followed by 2 weeks of recovery. Left ventricular pressure measurements and weekly echocardiograms verified the development of HF. The right and left ventricular intrathoracic impedance (RVITI and LVITI, respectively) signals were used to determine the respiratory parameters of rate, TV, and MV. Compared to baseline (BL), during HF, the TV dropped 68% for RVITI and 61% for LVITI (P < 0.0001 for both). Correspondingly, MV dropped 34% for RVITI and 27% for LVITI (P < 0.0001 for both). The daily medians of the respiratory rate (RR) and the longest breath interval (LBI) did not change significantly from BL to HF and recovery. However, circadian variation of the RR and the LBI became blunted during HF development. All derived respiratory parameters showed the reverse trend during the recovery period. CONCLUSION: TV and MV change independently from the RR in early HF decompensation. Tracking the changes of TV and MV with an implantable device may provide an additional method for early HF detection and assessment of the response to therapy.
Subject(s)
Dielectric Spectroscopy/instrumentation , Dielectric Spectroscopy/methods , Heart Failure/diagnosis , Heart Failure/physiopathology , Pacemaker, Artificial , Animals , Humans , Pulmonary Ventilation , Reproducibility of Results , Sensitivity and Specificity , Swine , Swine, Miniature , Tidal VolumeABSTRACT
Intramuscular injection of tiletamine-zolazepam and xylazine is commonly used as a preanesthetic for veterinary surgical procedures and for short-term restraint. However, this combination can have marked cardiodepressive and hypothermic effects that persist for hours to days. Here we present a case report of these effects in a swine heart failure model.
