Revival and modification of the Mustard operation

Structural variations of pectinate muscles across sheep and rabbit atria

The venous inflow of each atrial cortex is asymmetric and coupled to geometry and outflow to produce optimal vortices and flow patterns in each chamber. In the right atrium, fiber orientation is dependent on the crista terminals and pectinate muscles, which produce a circumferential squeezing effect to propel blood into the desired direction. The left atrial fiber orientation is a more complex fiber that suits its its geometry and function. This study demonstrates the structural differences between the right and left atria.

BACKGROUND

The right and left atria play important roles in overall cardiac performance, both at rest and during exercise. Atrial dysfunction due to congenital or acquired heart diseases can result in significant disability or death. The prevalence of such conditions has been rising due to the increasing age of the population as well as the progressively larger number of patients with Grown-up congenital heart disease (GUCH).

METHODS

Left and right atria were collected from rabbits and juvenile sheep, and pattern recognition and image analysis were used to illustrate the microstructure and orientation of the pectinate muscles.

RESULTS

The aim of this study is to observe the differences in the structure of the pectinate muscles in both rabbits and sheep. Through image analysis and pattern recognition, we were able to identify the orientation of the patterns that can help produce off-the-shelf patches that are capable of mimicking and/or reproducing most of the functions of normal atrial tissue.

CONCLUSION

The microstructure of the pectinate muscles is unique and provides remarkable functionality to the atria.

Combined Warden and Mustard procedure for late presenting transposition with anomalous pulmonary venous connections and regressed left ventricle

The presence of systemic and pulmonary venous anomalies in late presenting transposition of great arteries (TGA) may make standard atrial switch procedures difficult, necessitating modification in the surgical procedure. We present a case report of a 13-year-old boy with a partial anomalous connection of right superior pulmonary vein with TGA and regressed left ventricle, where a combination of Warden procedure and Mustard procedure was used.

Characterization of morphology and function of the 'neo-atria' after a modified Mustard operation

Background: There is a pressing need to improve early and long-term results of the Mustard operation. A modification of the operation was introduced at the Aswan Heart Centre for this purpose which relies on creating new functional atria rather than the two rigid channels in the classical Mustard operation.

Objectives: To evaluate the morphology and function of the neo-atria, shortly after modified mustard operation for a ‘neglected’ patient with TGA, VSD and severe pulmonary hypertension.

Methods: A 6-year-old with neglected TGA, VSD and pulmonary hypertension presented with severe cyanosis, clubbing and haemoconcentration (Hb 22 g/dL), underwent the modified Aswan-Mustard operation (MAM) with rapid smooth postoperative recovery. Repeated 2D echograms and multi-slice CT scans, followed by 3D segmentation, were performed after the operation. The size, shape, and morphology of the neo-atria were measured and measurements of the patterns of instantaneous filling and emptying of the right and left ventricles were quantified.

Results: The neo-systemic venous atrium consisted of three components with a combined volume of 78 mL/m², all of which contributed to the reservoir, conduit, and importantly contractile function of the neo-atrium. The pulmonary venous atrium consisted of two components with a combined volume of 66 mL/m². These measurements were made at atrial end diastole. The volumes of the systemic venous and the pulmonary venous diminished to 51 and 54 mL/m², respectively, at the end atrial systole - indicating relatively preserved contractile functions.

Conclusion: Following the modified Aswan-Mustard operation, neo-atrial function was relatively well preserved compared to the classical operation. The long-term results of these findings and their effects on quality of life need to be studied further.