Coronary tortuosity and its role in myocardial ischemia in patients with no coronary obstructions

Abstract

The objective of this study is to make a review of the narrative of coronary artery tortuosity (CAT) approaching several situations in clinical practice where tortuosity can have a relevant role, and also evaluate if tortuosity can be related to the presence of myocardial ischemia in patients without coronary obstruction using scientific evidences in medical literature. Textbook of applied Physiology in Cardiology with study of coronary circulation, theoretical articles with studies of Hemodynamics, Fluid and Mechanical Dynamic, and experimental articles with simulation in computers were used as support to answer this last question. Introduction Coronary circulationThere are two basic types of coronary vessels: conductance and resistance vessels. The epicardial arteries, right and left, and its main and major branches that emerge in acute angle of relative large caliber work as vessels of conductance offering in the diastole minimum resistance to the blood flow. The deep perforators that originate in a right angle of the epicardial arteries penetrate deeply in the myocardial walls and nurture sub endocardial layers offering great resistance to the flow mainly in the ventricular systole. They are responsible for the coronary flow autoregulation maintaining it adequately in broad spectrum of the pressure variation and increasing the flow in exercising situations mainly through the local metabolic regulation. Microcirculation is part of the coronary circulation constituted by arterioles and capillaries responsible for regulating the oxygen supply to the myocardium.The heart is a highly aerobic organ, but it depends almost exclusively on the oxidation of the substrates to generate energy which will move it and has almost no oxygen reserve. It receives about 5% of cardiac output and it is a little perfused organ, but it is the organ that has the highest oxygen extraction of the organism.Taking into consideration Fick's equation (oxygen consumption = coronary flow X arteriovenous difference of oxygen), we verified that the physiological determinants of the coronary flow are the same that command the demand and consumption of oxygen: blood pressure, heart rate, ventricular wall tension, dP/dt maximum.According to Poiseuille's law, the flow in any vessel system is directly proportional to the difference of pressure in its extremities, and inversely proportional to the resistance of the system, which is in turn proportional to the length of the tube, viscosity of the fluid and inversely proportional to the fourth power of the radius (most important factor). Influences of vasomotility of the autonomous nervous system, of drugs, mainly of local autoregulation, determine variations in the flow. Due to cyclical pressure and variations and myocardium tension, the coronary flow, in the systole represents from 25% to 30% of the total, and from 70% to 75% in the diastole.Factors that can affect myocardial consumption of oxygen and consequently the coronary flow can be divided into 3 groups: a) Factors that affect consump...

Relationship between sclerostin and coronary tortuosity in postmenopausal females with non-obstructive coronary artery disease

“…Coronary arteries tend to be the most tortuous arterial system secondary to, probably, the repetitive cardiac motions [28]. In our study, older age was independently associated with the presence of CT.…”

Non-electrocardiography- and electrocardiography-gated computed tomography angiography for the evaluation of feline coronary arteries

“…In one cat with type III branching (i.e., three main CA branches simultaneously extending from the LMCA), we observed severe tortuosity of the Pc and two additional efferent branches, a pattern that has not been reported in previous studies. Studies of humans have reported that coronary tortuosity may lead to alterations in coronary flow, resulting in a reduction in coronary perfusion pressure distal to the tortuous coronary arterial segment, subsequently leading to myocardial ischemia ( 19 – 21 ). Moreover, coronary tortuosity is positively associated with arterial hypertension and the female sex ( 19 ).…”

“…Studies of humans have reported that coronary tortuosity may lead to alterations in coronary flow, resulting in a reduction in coronary perfusion pressure distal to the tortuous coronary arterial segment, subsequently leading to myocardial ischemia ( 19 – 21 ). Moreover, coronary tortuosity is positively associated with arterial hypertension and the female sex ( 19 ). The cat with coronary tortuosity herein was a 3.6-year-old intact male that exhibited normal clinical findings on the basic health check-up.…”

Impact of coronary artery tortuosity in ischemic and non-ischemic cardiovascular pathology

“…Although overlooked in the past as a potential cause for myocardial ischemia, the contribution of CAT for myocardial ischaemia was reconsidered in the last decade [19]. In patients with significant atherosclerosis, several studies addressed the impact of coronary tortuosity on atherosclerotic proliferation, based on the principle that wall stress is the main causal factor for atherosclerotic plaques [20].…”