Assessment of Thoracic Blood Volume by Computerized Tomography in Patients With Heart Failure and Periodic Breathing.

BACKGROUND

Periodic breathing (PB) is often observed in patients with HF at rest, with sleep and during exercise. However, mechanisms underlying abnormal ventilatory control are not entirely established.

METHODS

Eleven subjects with HF (10 males, age = 69 ± 12 y) and 12 age-matched control subjects (8 males, age = 65 ± 9 y) participated in the study. PB was defined as a peak in the 0.003-0.04 Hz frequency range of the flow signal during 6 minutes of awake resting breathing. Thoracic blood volumes (Vt, thorax; Vh, heart; Vp, pulmonary), mean transit times (MTTs), and extravascular lung water (EVLW) were quantified using computerized tomography.

RESULTS

PB was observed in 7 subjects with HF and was associated with worse functional status. The HF PB-present group had thoracic blood volumes nearly double those of control and HF PB-absent subjects (volumes reported as mL/m2 body surface area, P values vs control: control = 813 ± 246, HF PB-absent = 822 ± 161 P = .981, HF PB-present = 1579 ± 548 P = .002). PB was associated with longer pulmonary MTT (control = 6.7 ± 1.2 s, HF PB-absent = 6.0 ± 0.8 s, HF PB-present = 8.4 ± 1.6 s; P = .033, HF PB-present vs HF PB-absent). EVLW was not elevated in the PB group.

CONCLUSIONS

Subjects with HF and PB at rest have greater centralization of blood volume.