Left ventricular function during hyperemia: A dive into the unknown

Excerpt

The relationship between myocardial ischemia and left ventricular (LV) dysfunction was described almost 30 years ago by Hauser et al1 who observed the appearance of regional myocardial dysfunction during coronary angioplasty by two-dimensional echocardiography. Following these observations, the theory of the ischemic cascade was developed, and abnormal myocardial perfusion was recognized as an early manifestation of ischemia. Myocardial ischemia is the mismatch between oxygen/metabolites supply and metabolic needs of myocardial cells. An inadequate blood flow causes an impairment in venous return and, consequently, accumulation of catabolites and tissutal acidosis that further contributes to the deterioration of LV function. In the ischemic cascade, there is a clear association between blood flow, oxygen supply, development of ischemia, and diastolic/systolic functional impairment. It is now clear that ischemia is the trigger for LV dysfunction, and it can be observed both after exercise and pharmacological stress test by dobutamine, which can activate the ischemic process increasing the oxygen demand. Maldistribution of flow itself, which can be observed during hyperemia induced by vasodilators, not necessarily induces ischemia unless horizontal and/or vertical coronary steal, affecting the regional blood flow, occur. …