The role of 3-dimensional echocardiography in the assessment of atrioventricular valves in congenital heart disease

Professor of Pediatrics, University of Toronto Faculty of Medicine,
Director, Section of Echocardiography, Division of Cardiology, Hospital for Sick Children, Toronto, Ontario, Canada
Jeffrey F. Smallhorn

【Outline】
This presentation will deal with a newer modality that is 3-dimensional echocardiograpy in the assessment of left and right atrioventricular valves in congenital heart disease. Abnormalities of the left A-V valve, both pre and postoperatively are one of the most common causes of mortality and morbidity in atrioventricular septal defect. Preoperatively those patients with dysplastic leaflets, in particular in the presence of a small ventricular component have a worse outcome than cases where the A-V valve leaflets are better formed. In other instance the surgical repair in itself results in damage to the left A-V valve, invariably from poor coaption of the leaflets, dehiscense of the sutured cleft or the leaflets themselves from the patch used to close the interventricular defect. Other abnormalities of both the left and right atrioventricular valves are less common in congenital heart disease, however 3-dimensional echocardiography can provide valuable additional information in this patient group.
While two-dimensional echocardiography provides invaluable information, both pre and postoperatively it is often difficult to mentally reconstruct a 3-dimensional image of the atrioventricular valves. Experience from adult patients with rheumatic mitral valve disease would support the notion that 3-dimensional echocardiography may have an important role in cases with congenital abnormalities of the atrioventricular valves.
【Equipment】
Although transthoracic 3-dimensional echocardiography is feasible, in our experience it does not provide adequate detail with the current generation of probes. Transesophageal echocardiography is an ideal technique for collecting 3-dimensional data, however in paediatric cases it usually requires a general anaesthetic. There is also a current limit to patient size as an adult omniplane probe has been necessary in our experience. This therefore limits the studies to patients who are approximately 11 kg and above. This is a significant limitation as much of the morbidity occurs in patients who are below this current weight limitation.
【Technique】
We currently collect a data set of 61 slices at 3 degree increments with respiratory and ECG gating. This data is stored on a MO disc and then processed on an offline unit for 3-dimensional reconstruction. Although it is possible to collect both anatomical and flow information, the latter is only processed as directional which makes interpretation of jet lesions difficult.
【Reconstructed images】
The reconstructed images provide detailed new information about the status of the atrioventricular valve, in particular leaflet area, commissure length and sites of poor coaption. This information is currently being used on a regular basis by our surgical group to help with pre and postoperative decision processes.
【References】
1）Poirier NC, et al: A novel repair for patients with atrioventricular septal defect requiring reoperation for left atrioventricular valve regurgitation. Eur J Cardiothorac Surg 2000; 18: 54-61
2）Najim HK, et al: Complete atrioventricular septla defects: Results of repair, risk factors and freedom from reoperation. Circulation 1997; 96 Suppl II: II311-315
3）Sittiwanagkul R, et al: Echocardiographic assessment of obstructive lesions in atrioventricular septla defects. JACC 2001; 38: 253-261
4）Bergin, et al: Partial atrioventricular canal defect: Long-term follow-up after initial repair in patients >40 years old. JACC 1995; 25: 1189-1194
5）El-Najdawi, et al: Operation for partial atrioventricular septal defect: A forty year review. J Thorac CVS Surg 2000; 119: 889-890