Temporal haemodynamic changes after bisoprolol treatment in patients with uncontrolled hypertension.

BACKGROUND

Anti-hypertensive drugs are widely used to control blood pressure, yet their effects on haemodynamics, especially in Chinese populations, and the potential for non-invasive methods to monitor these changes, are poorly understood. This study aimed to determine the early and late effects of bisoprolol treatment on blood pressure, cardiac output (CO), stroke volume (SV), heart rate (HR), systematic vascular resistance (SVR), and inotropy measured in Chinese patients with hypertension.

METHODS

Twelve Chinese subjects (median age: 55 years, interquartile range: 52-58 years; 33% male) with uncontrolled hypertension were recruited at the Prince of Wales Hospital in Hong Kong and haemodynamic measurements were assessed using a non-invasive Ultrasonic Cardiac Output Monitor (USCOM). Seven hourly measurements were taken before and after bisoprolol 2.5 mg on day 1 (T0 to T6), and in nine patients this was repeated six weeks later (TF0 to TF6). Any BP change of 5 mmHg was considered clinically significant and P<0.05 was considered statistically significant.

RESULTS

On day 1 (N=12), there was a significant drop in median CO [4.9 (4.7-5.6) 3.8 (3.3-4.7) L/m, P<0.0001] associated with a compensatory increase in SVR [1,698.1 (1,584.6-1,894.3) 2,222.6 (1,777.4-2,712.5) d·s·cm, P<0.0001] at T2. The median dBP {92 [87-95] 86 [79-89] mmHg, P=0.0002} and MAP {110 [104-114] 104 [101-109] mmHg, P=0.038} reduced significantly 6 hours after bisoprolol treatment. Except for HR, all other measured haemodynamics returned to baseline at T6. On week 6 (N=9), SVR was generally reduced, but major parallel swings in CO and SVR were still evident. All patients showed a trend to lower blood pressure, SVR, and inotropy (P<0.05), but HR, SV, and CO returned to baseline values after 6 weeks treatment (P>0.05).

CONCLUSIONS

The acute haemodynamic changes between 6 hours of the first dose and the dose after 6 weeks of bisoprolol treatment are similar. Long-term therapy can effectively reduce blood pressure by reducing SVR.