| |
| Chapter Objectives |
| |
| At the completion of this chapter the user will be able to: |
| |
- Describe Coronary Artery Anatomy and Dominance
- Evaluate Coronary Artery Anomalies
- Describe the Echocardiographic Appearance of Intracoronary Air in the Myocardium
- Describe the Anatomy of the Pericardium
- Indicate the Transverse Sinus and Oblique Sinus Echocardiographically
- Describe Pericardial Restraint
- Describe the Echocardiographic features of Pericardial Effusions, Tamponade, and Constrictive Pericarditis
- Describe Pleural Effusions
|
|
|
| Introduction |
| |
| While the echocardiographic evaluation mainly concerns the heart and the aorta, some extracardiac structures can be evaluated or visualized from transesophageal acoustic windows. The coronary arteries, while evaluated functionally and indirectly with wall motion, can be viewed with a transesophageal probe. Pericardial diseases can be evaluated and can have a major impact on cardiac function. Pleural effusions and hepatic diseases can also be evaluated with transesophageal echocardiography. |
|
| Coronary Arteries |
| |
The usual anatomic arrangement is two main coronary arteries: Left Main Coronary Artery (LMCA) and the Right Coronary Artery (RCA). The origin of the left main coronary artery in the left coronary cusp can be visualized in most patients in the left Sinus of Valsalva by slightly withdrawing the probe from the mid esophageal aortic valve short axis view while scanning the plane in the Sinus of Valsalva. Careful manipulation of the probe can demonstrate the bifurcation of the LMCA and the Left Anterior Descending Artery (LAD) coursing forward between the left atrial appendage and the pulmonary artery. The origin of the coronary artery is in the Sinus of Valsalva close to the tubular ridge; however the origin could be highly variable .
The origin of the RCA is from the right sinus of Valsalva. To view the RCA, slowly withdraw the probe from a mid esophageal aortic valve short axis as above but focusing on the right sinus of Valsalva. The RCA origin is usually more distal than the LMCA. The RCA is more difficult to visualize on TEE (50% v/s, 85% for LMCA). At the base of the heart in the AV grove, the RCA and the Circumflex form a circle. In the long axis a loop is formed by the LAD and the (PDA) posterior descending artery.
|
 |
| Coronary Artery Anatomy |
|
|
| |
|
|
| TEE LMCA Image |
TEE LMCA Video |
|
| |
|
|
|
| Epiaortic LMCA Image |
Epiaortic LMCA Video |
|
| |
|
|
|
| LMCA Image |
LMCA Video |
|
| |
|
|
|
| RCA Origin |
RCA Origin |
|
| |
|
|
|
| RCA Origin |
RCA Origin |
|
| |
| The normal diameter of the left main coronary artery is 4.2 ± 0.7 mm, slightly smaller in women (3.5 mm) than in men (4.3 mm). The diameter of LAD is in the range of 3.5 ± 1.0 mm and that of circumflex artery is 3.0 ± 0.6 mm. The RCA has an average diameter of 3.6 ± 0.8 mm. While pulse wave Doppler evaluation of blood flow in the coronaries using TEE is possible, it is often technically difficult and is of limited use in anesthesia settings. Predominant flow is noted during diastole with a velocity of about 0.6 cm/sec. Increased velocity of greater than 1 m/sec suggests stenosis.
The circumflex artery and the left anterior descending artery may be visualized in the same plane as the LMCA. The circumflex artery will course laterally whereas the left anterior descending artery courses anteriorly. The circumflex coronary artery can be visualized in the midesophageal 4 chamber view in the junction of the lateral wall and the left atrium. |
| |
|
|
|
| LAD and Cx Coronary Arteries |
LAD and Cx Coronary Arteries |
|
| |
|
|
|
| LAD and Cx Coronary Arteries |
LAD and Cx Coronary Arteries |
|
| |
|
| Coronary Artery Dominance |
| |
| Dominance in the coronary circulation is determined by the coronary artery that supplies the PDA (posterior descending artery). In about 85% of patients the PDA originates from the RCA (right dominant circulation). In 10-15% of patients the PDA is formed as a branch of the Circumflex (left dominant circulation). In the left dominant circulation the circumflex artery provides posteriolateral (PL or marginal) arteries to the inferior portion of the left ventricle. The system is codominant if RCA gives rise to PDA and the Circumflex supplies to the posterior left ventricle.
Apical segments of the left ventricle are usually supplied by the LAD. However, the PDA can supply the inferior apex. Because of this variable blood supply, some cases of isolated apical wall motion abnormality may be difficult to isolate a single artery as the source of problem. |
 |
| Right Dominant (85%) |
|
|
| |
 |
 |
| Co-Dominant (<5%) |
Left Dominant (10-15%) |
|
|
| Anomalies of the Coronary Arteries |
| |
| Most common anomalies include the origin of the circumflex from the right Sinus of Valsalva, pulmonary artery to coronary artery fistulas, fistulous connection between coronary artery and a heart chamber and the right atrium (RA) or right ventricle (RV). Abnormal origin of the LMCA could be from RCA, anterior Sinus of Valsalva, or of the RCA from the left posterior Sinus of Valsalva. Such anomalies are potential causes of coronary artery disease symptoms in young individuals. |
|
|
| |
|
|
|
| Aberrant LMCA Origin |
Aberrant LMCA Course |
|
|
| Coronary Aneurysm |
| |
| Coronary aneurysm is localized area of coronary dilatation, which is 1.5 times larger than the normal diameter. Coronary artery aneurysms are prone to thrombus formation or rupture. |
|
| Intracoronary Air |
| |
| During weaning from bypass, the heart is routinely evaluated for intracardiac air. If air enters the coronary ostium, it can impair blood flow and result in ischemia. Air bubbles tend to accumulate in the Sinus of the Valsalva close to the coronary ostium, more so in the right coronary cusp because of its superior location in the supine patient. Surgeons use various techniques to remove air bubbles like shaking the heart, tilting the table sideways, applying suction to the ascending aorta, needle aspiration of the air, coronary sinus perfusion to "blow the air out" or partially cross clamping the ascending aorta to increase the pressure in the coronary arteries to "blow the air through". TEE can be a useful tool in detecting air bubbles, locating the air bubbles and in guiding their removal. |
| |
|
|
|
| Inferior Wall Air |
Inferior Wall Air Resolved |
|
| |
