DK2985_C000 1..28 - AlSharqia Echo Club

Segmental Ventricular Function and Ischemia 181(A)(B)effusion and the presence of echogenic pericardial thrombus(42). The associated findings of regional dilatationand decreased wall thickness may increase the specificityof echocardiography for rupture. The sensitivity andspecificity of echocardiographic criteria for the diagnosisof rupture were investigated prospectively by Lopez-Sendon et al. (43). The presence of cardiac tamponade, apericardial effusion .5 mm and high density intrapericardialechoes suggestive of thrombus have a diagnosticsensitivity of 70% and specificity .90% for the diagnosisof myocardial rupture. Direct identification of themyocardial tear with TTE is difficult and TEE may beuseful in these unstable patients.VIII.PSEUDO ANEURYSM (d 1 d 2 )LA Aod 1 RVd 2 LVFigure 8.29 Difference between a pseudo and a true aneurysm.(A) In a pseudoaneurysm, the diameter of the orifice (d 1 )is smaller than the diameter of the aneurysm (d 2 ). (B) The oppositeis found in a true aneurysm (Ao, aorta; LA, left atrium; LV,left ventricle; RV, right ventricle).CORONARY ARTERY IMAGING ANDASSESSMENT OF CORONARYVASODILATOR RESERVEAlthough visualization rates of 58–90% have beendescribed for the left main coronary artery with TTE, theright coronary and circumflex arteries are visualised onlyin 40% and 30% of cases, respectively. The superiorresolution offered by the high frequency transducers(5–7 MHz) and the proximity of the coronary arteries toRVAothe esophagus account for improved coronary imagingwith TEE. A stenosis is defined as an area of apparentluminal narrowing with high-intensity echoes followedby normal lumen. Color flow imaging helps to identifyand follow the course of each coronary artery, a mosaicflow pattern often being present in the areas of suspectedstenosis. Coronary artery imaging begins in the basalshort-axis view at the esophageal level, just above theAoV leaflets. Anteflexion and leftward tilt of the probetip usually reveals the ostium of the left main coronaryartery and minor adjustments permit visualization of thewhole artery. Transducer retroflexion reveals the LADartery whereas the circumflex artery is seen as it passesleftward (on the right of the screen) and posteriorlyalong the left atrioventricular groove. The ostium of theRCA is usually visualized between 6 and 7 o’clock withthe probe tip tilted rightward and retroflexed, whereas itsproximal portion is seen extending towards the bottomof the screen. Although visualization of the coronaryarteries is possible with single-plane and biplane TEE,evaluation is limited mainly to the left main coronaryartery and the very proximal epicardial vessels (44)(Figs. 8.2 and 8.3). The numerous imaging planes providedby multiplane TEE allow enhanced visualizationof extended lengths of the coronary arteries and providea more reliable appraisal of any given abnormality.Tardif et al. (45) reported a sensitivity and specificity of100% for detection of left main coronary artery narrowingwhen compared with angiography. In addition, the proximalsegments of the LAD, circumflex, and right coronaryarteries were visualized in 84%, 80%, and 62% of patients,respectively. The sensitivity and specificity for detectionof proximal stenosis were, respectively, 80% and 100%for the LAD artery, 89% and 100% for the circumflexartery, and 82% and 100% for the RCA. It is also possibleto evaluate the coronary flow vasodilator reserve withTEE, in order to determine the functional significance ofa coronary stenosis (46). The coronary vasodilatorreserve is defined as the ratio between the maximal(hyperemic) and baseline flow and its assessment requiresthe use of a physiologic stimulus (coronary occlusion) orvasorelaxant drugs (adenosine, dipyridamole, papaverine).The coronary hyperemic response is impaired not only inpatients with a significant epicardial coronary stenosis,but also in those with systemic hypertension, diabetes mellitus,hypertrophic cardiomyopathy, or syndrome X whocan have microvascular disease. Using color Dopplerflow and adjusting the PW Doppler sample window as parallelas possible to the coronary flow, baseline velocitiesare measured. A vasodilator drug is then administeredand coronary blood flow velocity is measured again.Iliceto et al. (47) studied LAD coronary artery velocitiesin 15 patients and observed that the flow reserve was2.94 in normal patients and 1.46 in those with significant