الفهرس 
Ischemic Heart Disease; Definition and pathophysiologyOnly 14 pages are availabe for public view
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Abstract
Coronary artery disease (CAD) remains a principal cause of morbidity and mortality worldwide. Patients with Coronary artery disease experience significant reductions in their quality of life due to limitations of activity or, potentially, inability to return to ordinary work once the diagnosis of CAD is made. Many of those subjects have viable but dysfunctional myocardium, where akinetic or severely hypokinetic myocardium keeps the ability to contract if perfusion improves.
Percutaneous coronary intervention (PCI) is an established procedure for the treatment of coronary artery disease. Its usefulness in symptom relief is well established. However, the effect of PCI on systolic and diastolic function in patients with preserved baseline left ventricular systolic function is unknown, and results of echocardiographic assessment of systolic and diastolic ventricular function following successful elective PCI have been contradictory and confusing. Recently, tissue Doppler echocardiography has emerged as a sensitive and quantitative measure of both systolic and diastolic longitudinal myocardial function. Furthermore, it has been reported that impaired left ventricular longitudinal function may precede circumferential ventricular dysfunction in patients with coronary artery disease.
There are various methods, both invasive and non-invasive, for assessing cardiac function and determining the heart’s performance. Echocardiography remains central in evaluating cardiac structure and function due to its non-invasive nature, high availability and minimal risk profile. In 1995, Chuwa Tei described the myocardial performance index (MPI), defined as the sum of isovolumic contraction and relaxation times divided by the ejection time (ET). MPI has since gained acceptance as a reliable method for the combined evaluation of left ventricular (LV) systolic and diastolic performance, with potential advantages over other indexes in many cardiac diseases. MPI is more reflective of overall cardiac function than systolic or diastolic function alone, and applied to independently assess the myocardial performance of left and right ventricles. MPI has since been studied in several other cardiac disorders including heart failure, myocardial infarction (MI), systemic hypertension (HT) and diabetes mellitus (DM) and found to predict both worsened morbidity and mortality. Although alteration of MPI in patients with MI is well known, there were no satisfactory data about MPI in patients with stable CAD, and the relation between MPI and the severity of coronary atherosclerosis in patients with stable CAD has not been clearly determined yet.
Tissue Doppler (TDE) echocardiography is another emerging real time ultrasound techniques that provide a measure of wall motion. It offers an objective means to quantify global and regional left and right ventricular function and to improve the accuracy and reproducibility of conventional echocardiography studies. Radial and longitudinal ventricular function can be assessed by the analysis of myocardial wall velocity and displacement indices. A quick and easy assessment of left ventricular ejection fraction is obtained by mitral annular velocity measurement during a routine study, especially in patients with poor endocardial definition or abnormal septal motion.
It was hypothesized that although not evident on standard 2-dimensional echocardiography or contrast ventriculography, reduced regional contractile function distal to coronary artery stenosis may be present in patients with coronary artery disease and that PCI would have the potential to improve ventricular systolic and diastolic function after successful angioplasty.