Diagnosis of ventriculo-arterial discordance (transposition of the great arteries) by contrast echocardiography

[Diagnosis of cardiovascular diseases using suprasternal M-mode echocardiography]

The suprasternal approach can be used to image the aortic arch, the right pulmonary artery and the left atrium. Dilatation or dissections involving the aortic arch were detected echocardiographically from the suprasternal notch. The echocardiogram of the right pulmonary artery is altered in cases of acute and chronic pulmonary hypertension. Intrapulmonary thrombi in patients with acute pulmonary embolism were visualized with this technique. A volume overloading of the pulmonary circulation due to a congenital left to right shunt, as well as a decreased pulmonary blood flow due to a congenital right to left shunt causes characteristic changes in the wall motion pattern of the right pulmonary artery. Hypoplasia or aplasia of the central pulmonary arteries can be diagnosed as well. Imaging of the left atrium from the suprasternal notch may help to differentiate between supraventricular and ventricular rhythm disturbances. The suprasternal approach is therefore recommended to be used as a routine part of each echocardiographic examination.

Two-dimensional echocardiographic discrimination of normal from abnormal great artery relationships

A prospective study was performed to determine the diagnostic accuracy of precordial two-dimensional echocardiographic techniques in discriminating normal from abnormal great artery relationships. We studied 503 children using standard parasternal short-axis view and a modified technique called rotating high long-axis view (RHLAV). In RHLAV, there is rapid superimposition of the proximal courses of the two great arteries seen by rotation of the ultrasonic beam. Discrimination was based on the crossing great artery relationship seen with normally related great arteries (NRGA) and the parallel courses found in both transposition and malposition of the great arteries (TGA/MGA). Using the RHLAV, the great artery interrelationship was accurately determined in all 503 patients. Precordial two-dimensional echocardiography can accurately discriminate great artery relationships and is a useful addition to other two-dimensional echocardiographic techniques.

Identification of normal and transposed great arteries by contrast M-echocardiography in the newborn: a combined suprasternal and precordial approach

Diagnosis of complete transposition of the great arteries (TGA) by M-mode echocardiography depends on the correct identification of the aorta and the pulmonary artery at their roots. We describe a contrast M-mode echocardiographic technique which combines suprasternal and precordial views in which the two great arteries are visualized simultaneously. After venous injection of 1-3 ml 5% dextrose, the sequence and relative intensity of opacification of the great arteries are recorded in both views and then matched to each other. Because in the suprasternal view the aorta is always superior and the pulmonary artery inferior, the characteristics of opacification of these two arteries in the suprasternal view are used as markers for their proper identification in the precordial view. In four normal newborns contrast medium filled only the pulmonary artery. In six newborns with cardiovascular malformations with shunts and normally related great arteries, in which the contrast medium preferentially filled either the aorta (five patients) or the pulmonary artery (one patient), matching the record from the precordial view to that from the suprasteral view proved that the anterior vessel was indeed the pulmonary artery, and the posterior vessel the aorta. In five newborns with d-TGA the contrast medium preferentially filled the aorta, and the combined suprasternal and precordial approach proved that the aorta was anterior and the pulmonary artery posterior. This method is independent of the direction of venous drainage or site of injection.

Detection of persistent ductus in hypoplastic left heart syndrome by contrast echocardiography

A patient with hypoplastic left heart syndrome was studied using contrast echocardiography after peripheral venous injection of dextrose. The combination of the parasternal and suprasternal approach allowed for identification of the right ventricular cavity, excluded the presence of right-to-left intracardiac shunts, and established normal ventriculoarterial connections. From the abdominal approach, the abdominal aorta was identified as an echo-free space corresponding to this structure in position, which became opacified after peripheral injections of dextrose into the left-hand vein. In view of the suprasternal and parasternal findings opacification of the abdominal aorta could only have occurred in the presence of a pulmonary artery to descending aorta shunt through a persistent ductus arteriosus.

Wall motion characteristic of the right pulmonary artery in the suprasternal echocardiogram

This study describes the motion pattern of the right pulmonary artery (RPA) as it can be assessed from the suprasternal echocardiogram. The motion characteristic of the RPA is dependent on hemodynamic factors within the lumen of the RPA and those within the left atrium and the aortic arch. During atrial contraction the superior wall of the left atrium separates from the inferior wall of the RPA (IWRPA) and produces an "a" dip in the wall motion of the IWRPA. During isovolumic contraction the RPA is shifted upward (IC point). The incisura in the pulmonary artery pressure curve reflecting pulmonic valve closure can be seen by a sudden decrease in the diameter of the RPA (PC point). In conditions coinciding with pulmonary arterial hypertension, the overall diameter of the RPA increases, and the IC and PC points are flattened or even absent. Thus, changes in hemodynamics caused by pulmonary or cardiac disease may be analyzed noninvasively on the basis of altered wall motion of the RPA.

Scanning suprasternal echocardiography

Scanning suprasternal echocardiography was performed in 280 patients with a variety of cardiac anomalies. By using the special suprasternal transducer on the suprasternal notch, the aortic arch, right pulmonary artery, and left atrium were recorded superoinferiorly. From this reference position various scanning techniques were made to record the main pulmonary artery, pulmonary valve, ascending aorta, aortic valve, and distal aortic arch, wherever possible. These scans made it possible to assess (a) the integrity and size of right pulmonary artery and main pulmonary artery in pulmonary atresia, stenosis of origin of right pulmonary artery, pulmonary artery banding, kinked Waterston anastomosis, and aneurysm of pulmonary artery; (b) relative positions of aortic valve and pulmonary valve in malposition complexes; (c) the position and size of the aortic arch in tetralogy of Fallot and aortic coarctation. Measurements of the left atrium made by suprasternal echocardiography were consistently larger than those made by praecordial echocardiography. Changes in relative sizes of aortic arch, right pulmonary artery, main pulmonary artery, and left atrium were also documented in the various cardiac anomalies. The atrial baffle after Mustard repair for d-transposition of the great arteries and the atrial membrane in cor triatriatum were also demonstrated. The introduction of scanning techniques has thus widened the scope of suprasternal echocardiography.

Echocardiographic identification of aorta and main pulmonary artery in complete transposition

No completely reliable echocardiographic technique has been described for the separate identification of the aorta and main pulmonary artery in complete transposition of the great arteries. A mechanical wide-angle (60 degrees) sector scanner has been applied to this problem in 17 infants and young children, including 8 newborns before angiocardiography. In all patients a longitudinal scan (saggital section) identified the main pulmonary artery by its directly posterior course immediately beyond the pulmonary valve, and the aorta by its retrosternal course upwards before turning posteriorly above the main pulmonary artery. In addition, a high transverse scan showed the precise spatial relation of the great arteries, and, in 11 of the 17, tilting the scanning plane upwards showed branching of the main pulmonary artery. In 8 infants examined with M-mode echocardiography, an upward sweep from the pulmonary valve showed abrupt termination of the echo from the posterior wall coinciding with the posterior arching of the main pulmonary artery.