Atrial Correction (Modified Senning) of Transposition of the Great Arteries and Intact Atrial Septum with Regressed Left Ventricle and Pulmonary Hypertension: A Video Presentation

INTRODUCTION

Transposition of the great arteries is the congenital malformation which results from the abnormal chamber connections of atrioventricular concordance and ventriculoarterial discordance systemic diastolic dysfunction (SDD). It is generally classified as a type of conotruncal abnormalities, a group of abnormalities that has a common theme of deranged development of the cardiac outflow tract. In D-transposition, the aorta is anterior and to the right of the pulmonary artery. This pattern results in the systemic and pulmonary circulations occurring in parallel rather than in series.^[1,2]

These patients are subdivided into those with intact ventricular septum (50%), ventricular septal defect (25%), and ventricular septal defect with pulmonary stenosis (25%).^[1,2] Other associated cardiac anomalies include persistent ductus arteriosus, coarctation of aorta and transposition of the great arteries.^[3,4] Transposition of the great arteries accounts for 9.9% of infants with congenital heart disease or 0.2/1000 live births.^[5]

Many classification system have been used to describe the coronary anatomy in transposition of the great arteries.^[4-6] The Leiden classification is most commonly used.^[6-8] The most common coronary pattern in D-transposition of the great arteries (68%) consists of the left main coronary artery arising from the leftward coronary sinus giving origin to left anterior interventricular and circumflex coronary arteries. The right coronary artery arises from the right posterior sinus. In 20% of cases, the circumflex coronary arteries arise from the right coronary artery and passes behind the pulmonary artery. In 4.5% of cases, a single right coronary artery arises from the right posterior sinus or a single left coronary artery from the leftward coronary sinus.^[9] Intramural coronary arteries that proceed in the aortic wall for a distance before exiting to the epicardial surface, single coronary ostium, or separate ostia have been described.^[10] Inverted origin of the coronary arteries and inverted origin of the circumflex and right coronary arteries have been described in 3% and 7% of cases, respectively.^[11]

Although anatomical repair of transposition of great arteries is the treatment of choice, total abandonment of the atrial baffle procedures has not taken place because of the technical problems and “learning curve” of the former, select clinical applications and good short-term results of the later.^[11-14]

In the current era, the indications of the atrial switch operation have been limited to delayed/late presenters of D-transposition of the great arteries, transposition of the great arteries with complex coronary anatomy precluding an arterial switch operation, those who require atrial switch as a part of the anatomic repair of congenitally corrected transposition of the great arteries, those with isolated ventricular inversion, isolated atrioventricular discordance, D-transposition of the great arteries with the left ventricular outflow tract obstruction not amenable to a conventional Rastelli or Nikaidoh procedure and D- transposition of the great arteries with intact atrial septum, and severe pulmonary hypertension without a correctable cause.^[12-20]

Without surgery, the natural history of patients with all variants of transposition of great arteries was dismal, with 55%, 85%, and 90% mortality rates at 1 month, 6 months, and 1 year, respectively.^[11] After emerging as the only viable solution for patients with TGA, the Senning operation successfully enjoyed popularity, followed by abandonment in favor of the Mustard operation in the mid-1960s and early 70s, then an initial revival after modification introduced by Quaegebeur et al., before finally finding the current indications as enunciated above.^[12-20]

At present, surgeons can perform the Senning operation with low mortality and minimal morbidity by applying several technical modifications and paying meticulous attention to large and unobstructed venous pathways.^[11-20]

Following Senning’s operation, symptomatic caval obstruction is relatively rare, generally observed within weeks to several months after Senning’s operation and rarely beyond 1 year after surgery postoperatively.^[21] Superior vena caval obstruction is observed more frequently than obstruction of the inferior vena cava.^[22] Systemic venous obstruction has been reported more frequently after the Mustard operation (10–40%) than after the Senning operation.^[22-24]

Pulmonary venous obstruction contrary to systemic-venous obstruction is usually symptomatic.^[25] The reported incidence of this complication is 0–27%, much less frequent after the Senning operation.^[21,24] Baffle leaks lead to either bidirectional or predominantly right-to-left shunt. Right-to-left shunting in the absence of elevated systemic venous pressures is due to streaming of blood underneath the interatrial baffle with an incidence ranging from 20% to 73% after the Mustard operation and from 0% to 50% after the Senning operation.^[21]

Supraventricular dysrhythmias are frequent after an atrial switch operation. Sinus node dysfunction is present in 30% of operative survivors, more frequently in patients aged younger than 5 months at the time of surgery.^[26]

Deanfield et al. reported normal sinus rhythm in 84% of their patients in the immediate post-operative period, falling to 56% in sinus rhythm after a Senning correction, and to 66% after a Mustard operation at a mean follow-up of 7 years.^[27]

Intra-atrial re-entry tachycardia occurs in 2–10% of patients after an atrial switch operation and may be responsible for 3–15% incidence of post-operative sudden death.^[28] Atrial tachyarrhythmias are induced by re-entrant circuits from extensive atrial suture lines involved in a Senning or Mustard operation.^[28]

The incidence of post-operative tricuspid regurgitation following an atrial switch reaches as high as 52% and is more frequent in patients with transposition of the great arteries and ventricular septal defect.^[25,28-30]

Eventual right ventricular failure is not a time-related event.^[26] There is evidence in the published literature that onset or degree of right ventricular failure or exercise tolerance may be reduced when the Senning operation is performed earlier, particularly before the age of 1 year.^[31]

The operative mortality of the Senning correction in the published literature ranges from 0% to 10%.^{[14,22,29-39]} The incidence of late mortality ranges from 0% to 16.1% in recent series, most often in the form of sudden death.^{[14,22,29-39]}

At 25-years follow-up, the Senning operation had survival advantage as compared to Mustard operation (late cardiac mortality 2% at 10 years and 15% at 15 years, respectively).^[40]

Moons and associates in a multicenter study from Belgium compared the long-term outcome in 339 patients up to 30 years after Senning and Mustard operations.^[41] Both groups had a relatively high mortality rate, but actuarial survival at 10, 20, and 30 years was satisfactory at 91.7%, 88.6%, and 79.3%, respectively. The survival was slightly better for the Senning group.^[29-40]

We present here-in a 3-years old male child diagnosed as D-transposition of the great arteries and intact atrial septum with regressed left ventricle, Yacoub’s Type-B coronary arterial pattern, undergoing modified Senning operation under moderately hypothermic cardiopulmonary bypass, and St. Thomas based cold blood cardioplegia. Post-operative recovery was uneventful.

SURGICAL TECHNIQUES

CONCLUSION

The modified Senning operation currently is the treatment of choice in late presenters of transposition of great arteries with regressed left ventricle and/or pulmonary hypertension. The advantages include avoidance of use of large akinetic pericardial patch which is prone for shrinkage, use of maximal viable native tissue in the neosystemic and pulmonary venous pathway having growth potential, potential functional capacity with muscular contraction of the atrial chambers, and avoidance of akinetic patches that can scar, shrink, thicken, and further obstruct inflow, such as that seen with Mustard operation. Meticulous attention should be exercised at every step of the operation to avoid sinoatrial nodal injury, baffle leaks, and obstruction of the systemic and pulmonary venous pathway. An in situ pericardial patch for the neopulmonary venous pathway as was originally described by John Waldhausen should avoid any future pulmonary venous obstruction.^[42]