Cerebral blood flow in patients with chronic heart failure before and after heart transplantation

Arterial blood pressure and cardiac output are often reduced in patients with chronic heart failure (CHF). Counterregulatory mechanisms with increased neurohormonal activation and changes in the distribution of cardiac output are assumed to secure vital organ perfusion. However, clinical examination of patients with CHF frequently reveals neurological symptoms with dizziness and memory problems, suggesting altered brain perfusion. In this study we determined whether cerebral blood flow (CBF) is reduced in patients with New York Heart Association (NYHA) functional class III and IV (n=12) compared with healthy control subjects (n=12). Furthermore, we examined whether heart transplantation (n=5) could restore CBF.

CBF was estimated by single-photon emission computed tomography and (133)Xe as tracer, and middle cerebral artery velocity was measured by transcranial Doppler ultrasound.

In the CHF patients, CBF was 36+/-1 mL/min per 100 g, corresponding to a 31% reduction compared with the control group (52+/-5 mL/min per 100 g) (P<0.05). After heart transplantation, CBF increased from 35+/-3 mL/min per 100 g before transplantation to 50+/-3 mL/min per 100 g within the first postoperative month (P<0.05).

We conclude that CBF is substantially, but reversibly, reduced in patients with NYHA class III/IV heart failure. This phenomenon suggests that redistribution of cardiac output inadequately secures brain perfusion in patients with severe CHF.