Red blood cell (RBC) deformability, RBC aggregability and tissue oxygenation in hypertension

Arterial hypertension could be considered a progressive ischaemic syndrome interesting the macro and the microcirculation. In order to improve the cli nical and therapeutic approach to the treatment of arterial hypertension, r esearch has centered on blood flow to evaluate the different components and their very intricate relationships influencing the micro- and the macrocir culation. Of course the main problem is to study the link between the blood how and the peripheral tissue oxygenation. During hypertension very import ant alterations in rheological, mechanical and biochemical characteristics of erythrocytes and of blood flow have been shown. It is very relevant the increase in blood viscosity, the decrease in red blood cell (RBC) deformabi lity, the formation of RBC "rouleaux" and RBC aggregates. These hemorheolog ical determinants can favour an increase of peripheral resistances and of a rterial blood pressure, causing or worsening hypertension, a decrease in ox ygen transport to tissue and peripheral perfusion, a decrease of the active exchange surface area in the microvasculature, especially in complicated h ypertension. We have studied 320 patients: 123 with Essential Hypertension (EH) (M 59, F 64 aged 50 +/- 25 years); 81 with Secondary Hypertension (SH) without asso ciated other pathologies influencing hemorheology (M 42, F 39 aged 48 +/- 2 0 years); 116 SH with other pathologies or conditions associated influencin g hemorheology such as: diabetes, lipoidoproteinosis, obesity, smoking, HD, elderly, etc. (M 48, F 68 aged 46 +/- 20 years). Using a Laser-assisted Op tical Rotational Red Cell Analyzer (LORCA) acc. to Hardeman (1994) we studi ed Elongation Index (EI) and aggregation kinetics of red blood cells in the se patients. We also evaluated TcpO(2) and TcpCO(2) using a transcutaneous oxymeter (Microgas 7650, Kontron Instruments). In hypertensives we found a decrease in erythrocyte deformability (evaluated with EI), in erythrocyte a ggregation time, a fibrinogenaemia increase, an increase of shear rate to d isaggregate erythrocytes, a decrease in cellular oxygen delivery and tissue oxygenation, an impair ment of microcirculation. These changes may be invo lved in the development of arterial hypertension and in its pathogenesis. T hese patterns also are more impaired in hypertensives with diabetes, lipoid oproteinosis, etc. These patterns are not related with the age of the patients but they are si gnificantly and directly related (p < 0.01) with the patient hypertension-a ge. This could be a new way to realize a better treatment in hypertensives and a prevention of cardiovascular complications (i.e.: myocardial infarction, TIA, etc.).