Case Report

A 22-year-old man with Marfan syndrome presented with acute chest pain and hemodynamic instability. Urgent preoperative transesophageal echocardiography revealed a type-A aortic dissection with dilated ascending aorta, large pericardial effusion with signs of cardiac tamponade, and a bicuspid aortic valve with mild regurgitation. Surgical intervention consisted of valve-sparing prosthetic replacement of the ascending aorta and an endoprosthetic stent graft of the aortic arch. Recovery was uneventful.

One month later, transthoracic two-dimensional (2D) echocardiography showed normal left and right ventricular size and function and no abnormalities of aortic grafts. The bicuspid aortic valve showed a normal systolic opening with mild eccentric aortic regurgitation ( Figure 1 , Video 1 ). A real-time three-dimensional echocardiographic (RT3DE) en face view of the native aortic valve from its aortic side identified the mechanism of eccentric regurgitation as through a commissural triangular orifice between the two large cusps and a small underdeveloped third cusp ( Figure 1 ). This particular anatomic variant was not clearly evident by 2D echocardiographic visualization of the aortic cusps from the ventricular side. However, the RT3DE cine loop of valve opening and closing ( Video 2 ) confirmed its functionally bicuspid nature, as identified on 2D echocardiography and transesophageal echocardiography. By slicing and rotating the same aortic root data set, the origins of the left and right coronary arteries were also well visualized ( Figure 2 ).

(Left) Two-dimensional parasternal short-axis view of the aortic valve seen from its ventricular side, showing mild eccentric regurgitation (white arrow) of the native aortic valve, which appears bicuspid. (Right) Cross-sectional RT3DE visualization of the aortic valve from its aortic aspect, revealing a much smaller third cusp (yellow arrow) than the larger two, with which it creates in diastole a small triangular regurgitant orifice, leading to the eccentric aortic insufficiency jet observed on 2-dimensional echocardiography.

En face views of the ostia of the left main coronary artery (LMCA) (left) and right coronary artery (RCA) (right) were visualized as small slitlike orifices in the corresponding sinuses of Valsalva.

An RT3DE subcostal view of the abdominal aorta enabled a thorough spatial assessment of the aortic flap. Color Doppler RT3DE imaging of the abdominal aorta identified the true lumen, its dynamic size relative to the false lumen, and the perfusion of major aortic branches ( Video 3 ). The abdominal extension of the intimal flap was seen distally to the origin of the superior mesenteric artery, ending approximately at the level of the renal arteries, where the use of color Doppler identified a small intimal tear ( Video 4 ). Using electronic cropping tools, cross-sectional images of the abdominal aorta were obtained at various levels, and the small distal reentry tear between the two lumens previously identified with color Doppler could be actually appreciated in terms of its size, dynamic shape, and localization relative to the aortic branches ( Figure 3 , Video 5 ). The partial dynamic involvement of the right renal artery origin by the fragmented mobile flap could be also precisely identified ( Figure 4 , Video 6 ).

Three consecutive still frames of RT3DE cross-sectional view of the intimal flap in its distal segment. Images demonstrate the flap mobility, due to the presence of flow in both lumens. A slitlike reentry tear seen from above is demonstrated. The true lumen is intermittently collapsed by the false lumen.

Dissected abdominal aorta (Ao) seen in cross-section from below, demonstrating the partial involvement of the origin of right renal artery (RRA) by the fragmented intima.

Discussion

We have presented the case of a patient with Marfan syndrome operated for acute aortic dissection, in which follow-up RT3DE imaging provided important spatial information on flap extension and flow dynamics in the abdominal aorta, as well as on aortic root anatomy and valvular function.

Recent advances in RT3DE imaging allow the opportunity to reconsider the role of cardiac ultrasound for diagnosing and monitoring patients with aortic dissection. Echocardiography enjoys the unique combination of low cost, no radiation exposure, and the ability to provide rapid and safe comprehensive information on anatomic or functional abnormalities and flow dynamics at the bedside, which is critically important for the surgeon: localization of entry port and other intimal tears, flow characteristics in both true and false lumens, ventricular function, aortic valve anatomy and regurgitation, cardiac tamponade, and coronary and other aortic branch involvement. In patients with connective tissue disorders, such as those with Marfan syndrome, even after successful surgical reconstruction of the ascending aorta, the disease progresses relentlessly. The risk for complications may be much higher if a second predisposing factor coexists, such as a bicuspid aortic valve. Therefore, aortic valve anatomy and function must be accurately documented for risk stratification and choice of surgical approach (valve-sparing or replacement techniques). Especially when significant aortic regurgitation coexists, RT3DE imaging allows the measurement and monitoring of left ventricular volumes and systolic function with accuracy superior to that of 2D echocardiography. The dissected descending aorta remains a source of late complications, yet the decision to undertake repeat surgery must take into account a relatively high mortality rate. Because these patients are often young and require frequent monitoring during follow-up (annually if stable and even more frequently in the first year after surgery or if the abdominal aorta is dilated), there is growing interest in safe and cost-effective imaging tools to screen for complications and to plan timely elective surgery. No imaging method is ideal or sufficient to be used in isolation for this purpose. Contrast computed tomography may be inapplicable if significant renal failure coexists, magnetic resonance is contraindicated in patients with metallic devices, neither method can be used in unstable patients, and so on, so readily available alternatives must be considered.

Imaging of the abdominal aorta is feasible with RT3DE and may be used to evaluate the dimensions of true lumen and the presence and localization of distal intimal tears. Using cropping and navigation tools within the data set, dynamic images from atypical perspectives of the intimal flap and of its spatial relationship with major aortic branches are now possible. The capability to discriminate between static and dynamic branch obstruction in case of end-organ ischemia is crucial: static obstruction may be solved by vessel stenting at its origin, while dynamic obstruction can be excluded by closing the entry port and decompressing the false lumen. The persistence of flow within the false lumen is also important, because it is associated with higher morbidity and mortality. Serial examinations using RT3DE imaging can identify the subset of patients who require more extensive assessments using imaging tools with superior spatial resolution. The introduction of endovascular treatment has opened a new perspective for these fragile patients, yet it requires precise anatomic details and sizing. Unique RT3DE views of the aortic lumen and branches and the ability to quantify diameter, area, and shape may provide important spatial information. The value of RT3DE imaging in supplementing the conventional tomographic techniques for guiding and monitoring percutaneous procedures in aortic pathologies remains to be verified.

The aortic root just above the coronary ostia is the most frequent localization of intimal dissection in patients with Marfan syndrome. This case demonstrates the feasibility of RT3DE imaging to identify the coronary artery ostia and possibly their involvement by the intimal flap, if patient clinical condition and image quality allow. Offline analysis of the three-dimensional data sets may be done after the completion of the echocardiographic study, while the patient undergoes other tests or is being prepared for surgery. Of note, all data related to the present case were obtained from one three-dimensional data set containing the aortic root and two containing the abdominal aorta (with and without color Doppler), which required 3 minutes for acquisition and 10 minutes for offline image postprocessing. However, very good image quality, patient cooperation for breath holding, and stable cardiac rhythm are prerequisites that limit the applicability of RT3DE imaging in unselected patients.

In conclusion, RT3DE imaging may complement the standard imaging approach in patients with aortic dissection, particularly but not exclusively during postoperative serial follow-up. RT3DE imaging provides a wealth of information with proven prognostic value in a completely safe and rapid manner. Recent advances in transesophageal RT3DE imaging could further increase diagnostic accuracy for aortic dissection by ultrasound, and future experience will verify its clinical benefits.