Rheological aspects of coronary artery and coronary small blood vessel diseases (Syndrome X)

Abstract

The flow property of blood is one of the two major determinants of flow resistance, but it has not gained as much attention as the vascular component in haemodynamic investigations on ischaemic heart disease. Recent observations in some patients with typical angina pectoris but normal coronary arteriogram shed new light on this problem, since it became evident that merely severe rheological abnormalities can cause impaired coronary perfusion, while improvement of blood fluidity by plasmapheresis or haemodilution clearly increases coronary blood flow and coronary reserve. This, however, means that in coronary artery or small vessel diseases with already reduced flow forces and restricted coronary reserve, rheological factors would be more relevant than it was expected until now. The more the vasomotor reserve is recruited the more likely are microcirculatory disturbances with clinical signs caused by pathologically altered viscosity factors. It is therefore of clinical interest that in most patients with common coronary artery disease the haemorheological parameters differ from normal. This is also true for non inflammatory and inflammatory small vessel diseases, where the changes are even more pronounced. Although rheological abnormalities can be determined in ischaemic heart disease it is not possible to forecast effects on coronary microcirculation as long as we have no data on the myocardial microhaemodynamic.