Haemodynamic differences in untreated hypertension and hypertension treated with various beta-adrenoceptor antagonists.

1 As a rule, hypertension progresses from an early stage with a high cardiac output (CO) and an inappropriately normal total peripheral resistance (TPR) to later stages with a normal or decreased CO and a high TPR. 2 Low CO and high TPR can be considered detrimental to the blood perfusion in the tissues and organs and thus to their functional and structural integrity. 3 Among beta-adrenoceptor antagonists, some lower blood pressure by reducing CO, thus bringing about a reactive increase in TPR. The result is that, even though blood pressure is reduced, the haemodynamic conditions commanding regional blood flow are qualitatively similar to those in untreated hypertension. To what extent these circumstances may curtail the benefit expected from blood-pressure reduction deserves careful investigation. 4 Pindolol, a beta-adrenoceptor antagonist with an appropriate degree of intrinsic sympathomimetic activity (ISA), lowers blood pressure while lowering TPR and not unduly reducing cardiac performance. These features should on theoretical grounds lead to a greater improvement in the prognosis of hypertension.