Cardiac ultrasound: An Anatomical and Clinical Review

The merits of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the management of transient ischemic attack (TIA) and stroke patients remains matter of debate. Two hundred and thirty-one consecutive patients with a recent TIA or stroke for which no definite cause and indication for anticoagulation was assessed after standardized work-up underwent TTE and TEE. Echocardiographic findings were categorized into minor and major risk factors. A potential cardiac source of embolism was detected in 55% (127/ 231) of the patients by echocardiography, in 39% (90/231) only identified on TEE. Major risk factors, with an absolute indication for oral anticoagulation, were detected in 20% (46/231) of the patients, in 16% (38/231) of all patients identified on TEE only. A thrombus in the left atrial appendage was the most common major risk factor (38 patients, 16%). The presence of major risk factors was independent of age (chi2=1.48; P=0.224). The difference in proportions of cardiac sources detected in favor of TEE was highly significant in both patients 45 years of age (80/192; P<0.004). TEE proved superior to TTE for identification of a cardiac embolic source in patients with TIA or stroke without pre-existent indication or contraindication for anticoagulation. In patients with normal TTE, a cardiac source of embolism was detected by TEE in approximately 40% of patients, independent of age. More than 1 of 8 patients of any age with normal TTE revealed a major cardiac risk factor on TEE, in whom anticoagulation is warranted.

It is thought that the majority of cardiovascular (CV) events are caused by vulnerable plaque. Such lesions are rupture prone, in part due to neovascularization. It is postulated that plaque vulnerability may be a systemic process and that vulnerable lesions may co-exist at multiple sites in the vascular bed. This study sought to examine whether carotid plaque vulnerability, characterized by contrast-enhanced ultrasound (CEUS)-assessed intraplaque neovascularization (IPN), was associated with significant coronary artery disease (CAD) and future CV events. We investigated carotid IPN using carotid CEUS in 459 consecutive stable patients referred for coronary angiography. IPN was graded based on the presence and location of microbubbles within each plaque (0, not visible; 1, peri-adventitial; and 2, plaque core). The grades of each plaque were averaged to obtain an overall score per patient. Coronary plaque severity and complexity was also determined angiographically. Patients were followed for 30 days following their angiogram. This study found that a higher CEUS-assessed carotid IPN score was associated with significant CAD (≥50% stenosis) (1.8 ± 0.4 vs. 0.5 ± 0.6, P  < 0.0001) and greater complexity of coronary lesions (1.7 ± 0.5 vs. 1.3 ± 0.8, P  < 0.0001). Furthermore, an IPN score ≥1.25 could predict significant CAD with a high sensitivity (92%) and specificity (89%). The Kaplan–Meier analysis demonstrated a significantly higher proportion of participants having CV events with an IPN score ≥1.25 ( P  = 0.004). Carotid plaque neovascularization was found to be predictive of significant and complex CAD and future CV events. CEUS-assessed carotid IPN is a clinically useful tool for CV risk stratification in high-risk cardiac patients.

M-mode echocardiography is considered to be obsolete by many. The technique rarely is included in American Society of Echocardiography standards documents, except for M-mode measurements, which have limited value. The superior temporal resolution of M-mode echocardiography is frequently overlooked. Doppler recordings reflect blood velocity, whereas M-mode motion of cardiac structures reflect volumetric blood flow. The 2 examinations are hemodynamically complementary. In the current digital era, recording multiple cardiac cycles of two-dimensional echocardiographic images is no longer necessary. However, there are times when intermittent or respiratory changes occur. The M-mode technique is an effective and efficient way to record the necessary multiple cardiac cycles. In certain situations, M-mode recordings of the valves and interventricular septum can be particularly helpful in making a more accurate and complete echocardiographic cardiac assessment, thus helping to make the examination more cost-effective. Copyright (c) 2010 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.