الفهرس 
Coronary Artery EctasiaOnly 14 pages are availabe for public view
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Abstract
Coronary artery ectasia (CAE) has been observed by pathologists and cardiologists for more than two centuries. The most commonly used angiographic definition of CAE, albeit arbitrary, is the diameter of the ectatic segment being more than 1.5 times larger compared with an adjacent healthy reference segment
The exact mechanism of its development is unknown, but evidence suggests a combination of genetic predisposition, common risk factors for coronary artery disease and abnormal vessel wall metabolism .
Studies suggest that myocardial damage in patients with coronary ectasia might be induced by microthrombotic embolism and microcirculation disturbance .
Coronary endothelial dysfunction in humans may be temporally associated with myocardial perfusion defects and supports a role for the coronary epicardial and microcirculation endothelium in regulating myocardial perfusion .
Many recent studies revealed that these perfusion defects can improve in coronary ectatic patients under the effect of many pharmacological agents , such as antiplatelets and Trimetazidine .
Dipyridamole (DP) is a phosphodiesterase inhibitor that increases the intracellular levels of (cAMP) and (cGMP). By inhibiting cyclic guanine monophosphate (cGMP) PDE, DP enhances cGMP-dependent downstream vasodilatory effects in smooth muscle . DP reversibly inhibits platelet aggregation. Also, DP has antioxidative , anti-inflammatory , angiogenic and antianginal effects .
In the past there was too great an emphasis on side-effects that had been caused by high intravenous doses in experimental studies . Dipyridamole deserves a re-evaluation in the treatment and prevention of organ manifestations of atherosclerosis because of its advantageous spectrum of effects.
Based on these facts , the aim of our study was to detect the presence and extent of ischemia, and the effect of oral Dipyridamole therapy on the myocardial perfusion as measured by Tc-99m Sestamibi scintigraphy , in coronary artery ectatic patients .
The study included 30 patients with coronary artery ectasia who presented to Ain Shams University hospitals with chest pain and underwent elective coronary angiography within the period between February 2006 and August 2008, then were referred to the nuclear cardiology unit to undergo the first SPECT study .
All the patients were subjected to thorough history taking , clinical assessement ,12 –lead Electrocardiogram , mean corrected TIMI frame count measurements from their coronary angiograms , angiographic characterization of ectasia , searching for the distribution of ectasia among the different coronary vessels , and the extent of vessel affection , whether diffuse or segmental , and SPECT imaging to detect the presence of perfusion defects .
The 18 patients proved to have ischemia by the SPECT study were given oral Dipyridamole medication at a dose of 75 mg 3 times per day for one month . Four patients DROPped out of the study , and the remaining 14 patients were subjected to the 2nd follow up SPECT image , which showed the improvement of the summed difference scores among 12 of the studied population , while the 2 others did not improve .
The study results showed that the patient population of CAE was relatively young , with a mean age of 49±6 years , with male predominance (96%) , and the incidence of diabetes mellitus was significantly low (23%) .
Sixty per cent of the patients showed positive ischemia in their basal SPECT study , in spite of the absence of stenotic lesions in their coronary angiograms .
By comparing the ischemic versus the non ischemic groups , the study found that there was no actual statistical significant difference as regards the risk factors , the mean corrected TIMI frame counts , the distribution and the extent of vessel affection (P value >0.05) .
But on the other hand , there was a statistical significant increase in the incidence of diffuse ectasia in the ischemic group (P value <0.05) , together with increase in the incidence of segmental ectasia in the non ischemic one (P value <0.05) , meaning that the extent of ectasia can be used as a predictor for the ischemic burden of the disease .
The most commonly affected myocardial segments were the inferior segments , as mentioned by the radioisotope studies .
After one month of oral intake of Dipyridamole 3 times per day , there was an improvement in the mean summed difference scores for 12 of the studied population , from 2.63±3.08 to become 0.58±1.21 as shown in the follow up SPECT study , denoting a beneficial effect of the Dipyridamole on the myocardial perfusion in the non obstructive CAE patients .
We concluded that : although the coronary artery ectasia is different from atherosclerotic coronary artery disease , it can cause myocardial ischemia , with special prediletion to the inferior wall of the heart , is directly associated to the diffuse affection of the vessel , and can be treated with oral Dipyridamole therapy if given as a maintainance dose through a number of mechanisms