**3.11 Double outlet right ventricle**

The key feature of double outlet right ventricle (DORV) is the two great arteries arising primarily from RV. For each artery, RV should contribute more than 50% of it blood flow. There are four types of VSD in DORV patients: subaortic VSD, subpulmonary VSD, doubly committed VSD, and remote VSD. DORV with subaortic VSD is the most common variety in DORV. The conal septum here usually deviates anterior and leftward, and sometimes causes subpulmonary or pulmonary valve stenosis. If there is no pulmonary stenosis, pulmonary blood flow is determined by the relationship of SVR and PVR. If the VSD is subaortic and pulmonary stenosis exists, the presentation is similar to TOF. The degree of cyanosis is dependent on the severity of pulmonary flow obstruction.

DORV with subpulmonary VSD is caused by malalignment of conal septum, which should be differentiated from pure subpulmonary VSD. The conal septum is deviated to posterior and right, sometime causing subaortic narrowing. The Taussig-Bing malformation is a special variant of DORV with subpulmonary VSD, side by side great arteries, aorta at right side, and bilateral subarterial conus. The physiology of this variant is similar to d-TGA. Cyanosis is usually caused by inadequate mixing of systemic and pulmonary circulation, and improved atrial or ductal mixing by emergent balloon atrial septostomy and prostaglandin E1 may be needed.

In DORV with doubly committed VSD, conal septum is deficient, and VSD is usually nonrestrictive. The prevalence is rare, and the hemodynamic is determined by out flow tract obstructions. In DORV with remote VSD or noncommitted VSD, the defects can be within muscular septum or AV canal septum. Because the distance of VSD and semilunar valves are far, surgical management is sometimes restricted.

Different anatomical arrangements have impacts on hemodynamic presentation, and influence the surgical planning (Lancour-Gayet, 2008). In addition to confirming diagnosis, preoperative TEE should provide information that help to determine a suitable surgical procedure. The size and relative position of VSD to great artery locations should be evaluated by preoperative TEE. Color Doppler gives information of outflow tract obstruction. The presence of pulmonary stenosis or aortic stenosis, either valvular or subvalvular, can be imaged in multiple views. The relative size of both ventricles, the presence of AV valve straddling, the pulmonary valve to tricuspid valve distance, and presence of other associated cardiac anomalies should all be evaluated by preoperative TEE (Figure 18).

In most cases, the goal of surgery is to complete biventricular repair and restore normal circulation. Surgeons will establish unobstructed LV to aorta continuity, establish adequate RV to PA continuity, and repair associated lesions. Some patients with DORV and subpulmonary VSD are repaired with arterial switch operation after baffling the LV to PA through VSD. Occasionally, in patients with unbalanced ventricle or other associated

Double switch operation may be performed for patients with l-TGA. It is a combination of atrial switch operation and arterial switch operation. The preoperative TEE exam should evaluate the relationship of great arteries, presence of outflow tract obstruction, ventricular and valvular function, and associated intracardiac anomalies. The post-repair TEE exam should focus on the systemic and pulmonary venous return pathway, ventricular and

The key feature of double outlet right ventricle (DORV) is the two great arteries arising primarily from RV. For each artery, RV should contribute more than 50% of it blood flow. There are four types of VSD in DORV patients: subaortic VSD, subpulmonary VSD, doubly committed VSD, and remote VSD. DORV with subaortic VSD is the most common variety in DORV. The conal septum here usually deviates anterior and leftward, and sometimes causes subpulmonary or pulmonary valve stenosis. If there is no pulmonary stenosis, pulmonary blood flow is determined by the relationship of SVR and PVR. If the VSD is subaortic and pulmonary stenosis exists, the presentation is similar to TOF. The degree of

DORV with subpulmonary VSD is caused by malalignment of conal septum, which should be differentiated from pure subpulmonary VSD. The conal septum is deviated to posterior and right, sometime causing subaortic narrowing. The Taussig-Bing malformation is a special variant of DORV with subpulmonary VSD, side by side great arteries, aorta at right side, and bilateral subarterial conus. The physiology of this variant is similar to d-TGA. Cyanosis is usually caused by inadequate mixing of systemic and pulmonary circulation, and improved atrial or ductal mixing by emergent balloon atrial septostomy and

In DORV with doubly committed VSD, conal septum is deficient, and VSD is usually nonrestrictive. The prevalence is rare, and the hemodynamic is determined by out flow tract obstructions. In DORV with remote VSD or noncommitted VSD, the defects can be within muscular septum or AV canal septum. Because the distance of VSD and semilunar valves

Different anatomical arrangements have impacts on hemodynamic presentation, and influence the surgical planning (Lancour-Gayet, 2008). In addition to confirming diagnosis, preoperative TEE should provide information that help to determine a suitable surgical procedure. The size and relative position of VSD to great artery locations should be evaluated by preoperative TEE. Color Doppler gives information of outflow tract obstruction. The presence of pulmonary stenosis or aortic stenosis, either valvular or subvalvular, can be imaged in multiple views. The relative size of both ventricles, the presence of AV valve straddling, the pulmonary valve to tricuspid valve distance, and presence of other associated cardiac anomalies should all be

In most cases, the goal of surgery is to complete biventricular repair and restore normal circulation. Surgeons will establish unobstructed LV to aorta continuity, establish adequate RV to PA continuity, and repair associated lesions. Some patients with DORV and subpulmonary VSD are repaired with arterial switch operation after baffling the LV to PA through VSD. Occasionally, in patients with unbalanced ventricle or other associated

valvular function, and anatomy of outflow tract and neo-great arteries.

cyanosis is dependent on the severity of pulmonary flow obstruction.

**3.11 Double outlet right ventricle** 

prostaglandin E1 may be needed.

are far, surgical management is sometimes restricted.

evaluated by preoperative TEE (Figure 18).

anomalies, two-ventricle repair is not feasible and operation toward single ventricle physiology is needed.

Postoperative complications generally fall into four groups: LV failure, RV failure, arrhythmia, and residual shunts. Because LV flow is baffled through VSD to great artery, obstruction occurs with poor configuration of the patch or insufficient enlarged VSD size. It is especially difficult in DORV with remote VSD. Aortic insufficiency may occur due to surgical damage. Residual RVOT obstruction can occur whether the repair acquired infundibulotomy, outflow tract patch, or some form of RV to PA conduit. Intracardiac baffle may compromise RVOT flow, especially in DORV with subpulmonary VSD, because the VSD is very close to pulmonary orifice and infundibular septal band. Tricuspid insufficiency may happen if chordae resection and reattachment is needed to accommodate baffle implantation. After arterial switch operation, neo-PA or branched PA obstruction should be carefully surveyed. Residual shunt may be caused by incomplete VSD repair, baffle detachment, and unrecognized multiple VSDs. It is prudent to carefully evaluate the repair by TEE before leaving operation room.

Fig. 18. Double-outlet right ventricle. The mid-esophageal long-axis view demonstrates both aorta (Ao) and pulmonary artery (PA) arises from right ventricle (RV) and the presence of pulmonary stenosis (arrow) and ventricular septal defect (D). LV, left ventricle; RV, right ventricle.

### **3.12 Single ventricular physiology**

The functionally univentricular circulation, or single-ventricle physiology, is a heterogenous group of cardiac abnormalities. In most patients, there is hypoplasia of either the RV or LV

Intraoperative Transesophageal Echocardiography for Congenital Heart Disease 135

driving force to pulmonary circulation is SVC pressure. Part of the left to right shunt is removed, and thus relieving the volume load from single ventricle. Perioperative TEE exam includes the evaluation of the anastomosis site, PA morphology,AV valve function, and

Current approach for stage III operation is Fontan operation or total cavopulmonary connection. Intracardiac lateral tunnel or extracardiac conduit may be used to create cavopulmonary connection. In this stage, pulmonary flow is dependent on systemic venous pressure, and all the pulmonary flow is effective. Fontan fenestration is sometimes provided to offer a source to systemic circulation that is not dependent on passing through pulmonary circulation. The perioperative TEE exam includes evaluation of the patency of cavopulmonary connection, AV valve function, size and flow of fenestration, and

Fig. 20. There is a fenestration with shunt flow (arrow) between the extracardiac conduit (C) and right atrium (RA) after total cavopulmonary connection in a patient with tricuspid

Congenital heart disease is a complex disease entity of various severities. Intraoperative TEE offers valuable information about patients' anatomy and pathophysiology. In addition to diagnosis confirmation, TEE is a useful guide for surgical planning and anesthetic management. Intraoperative assessment by TEE images may be difficult due to complicated pathological presentations. A thorough understanding of anatomy, pathophysiology, and surgical procedure of congenital heart disease is required for

ventricular function.

atresia.

**4. Conclusion** 

interpretation of intraoperative TEE.

ventricular function (Figure 20).

which is unable to maintain a pulmonary or systemic circulation independently (Khairy et al., 2007). This anatomical category includes hypoplastic left heart syndrome, tricuspid atresia, and double-inlet LV (Figure 19). Two-ventricular repair may not be feasible in some complex congenital heart disease even with balanced ventricles, such as malpositioned or straddling AV valve, or DORV with a remote VSD, and single ventricle management strategy must be undertaken.

Fig. 19. Single ventricle physiology. (A) Hypoplastic left heart syndrome. The midesophageal short-axis view shows the mitral atresia (arrow) and hypoplasia of left ventricle (LV). (B) Tricuspid atresia. The mid-esophageal short-axis view demonstrates the tricuspid atresia (arrow) and hypoplasia of right ventricle (RV). RA, right atrium.

In single ventricle anatomy, the functional ventricle provides a common mixing chamber, and must pump both the systemic and pulmonary circulations, which easily lead to volume overload, cyanosis, or congestive heart failure. This pathophysiology encompasses a complex group of diseases. The presence of systemic and pulmonary outflow tract obstruction both contribute to the clinical manifestation.

Current surgical management of single ventricle is divided into 3 stages. Stage I operation technique is dependent on patients' status. Surgical palliation is to achieve following goals: unobstructive systemic blood flow, balanced and limited pulmonary blood flow, minimal AV valve regurgitation, nondistorted pulmonary arteries, and unrestricted return of blood to the ventricle. If pulmonary flow is unrestricted, pulmonary banding is done to minimize ventricular overload and avoid pulmonary hypertension. If systemic obstruction is noted, Norwood operation or Damus-Kaye-Stansel palliation is used. A systemic to pulmonary shunt, such as Blalock-Taussig (B-T) shunt is placed to provide pulmonary blood flow in patients with obstructed pulmonary circulation. In addition, AV valve repair and atrial septostomy may be needed according to patients' condition. The preoperative TEE exam includes the evaluation of AV and VA connections, AV valve morphology and function, degree of outflow tract obstruction, size and morphology of ventricles, and associated cardiac anomalies. The postoperative TEE exam should focus on the presence of systemic outflow tract obstruction, AV valve function, status of pulmonary blood flow and ventricular function.

Stage II operation mainly aims to connect SVC to PA and eliminate or restrict other sources for pulmonary blood flow. Bidirectional Glenn shunt and hemi-Fontan anastomosis are representatives. Bidirectional Glenn shunt is built from SVC to PA. After the operation, the driving force to pulmonary circulation is SVC pressure. Part of the left to right shunt is removed, and thus relieving the volume load from single ventricle. Perioperative TEE exam includes the evaluation of the anastomosis site, PA morphology,AV valve function, and ventricular function.

Current approach for stage III operation is Fontan operation or total cavopulmonary connection. Intracardiac lateral tunnel or extracardiac conduit may be used to create cavopulmonary connection. In this stage, pulmonary flow is dependent on systemic venous pressure, and all the pulmonary flow is effective. Fontan fenestration is sometimes provided to offer a source to systemic circulation that is not dependent on passing through pulmonary circulation. The perioperative TEE exam includes evaluation of the patency of cavopulmonary connection, AV valve function, size and flow of fenestration, and ventricular function (Figure 20).

Fig. 20. There is a fenestration with shunt flow (arrow) between the extracardiac conduit (C) and right atrium (RA) after total cavopulmonary connection in a patient with tricuspid atresia.
