The morphologic nature of noncommitted ventricular septal defects in specimens with double-outlet right ventricle

Essential Modifiers of Double Outlet Right Ventricle: Revisit With Endocardial Surface Images and 3-Dimensional Print Models

Hearts with double outlet right ventricle are a heterogeneous group of malformations in which a comprehensive diagnostic approach is required for tailored surgical management. This pictorial essay revisits essential modifiers of clinical and surgical importance in management of the patients with double outlet right ventricle using 3-dimensional volume-rendered endocardial surface images and 3-dimensional print models. Special emphasis is paid to the infundibular morphology, including the size and orientation of the outlet septum, relative to the margin of the ventricular septal defect, and the extent of the muscular infundibulum as an additional modifier of the distance between the ventricular septal defect margin and the arterial valve or valves.

Biventricular Repair of Double Outlet Right Ventricle: Preoperative Echocardiography and Surgical Outcomes

OBJECTIVE

To discuss the key anatomic features of double outlet right ventricle (DORV) assessed by preoperative echocardiography among patients treated with different types of biventricular repair.

METHODS

Surgical and echocardiographic databases were queried to identify patients who had undergone biventricular repair for DORV and had adequate preoperative echocardiographic imaging. All patients underwent pre- and postoperative echocardiography and clinical evaluation following discharge.

RESULTS

Two hundred sixty-two patients with DORV met the inclusion criteria of the study. The patients were divided into two groups-intraventricular tunnel repair (IVR) to the aorta (194 [74%] patients) or to the pulmonary artery with either concomitant arterial switch operation or double-root translocation (68 [26%] patients). Among 68 patients undergoing IVR to the pulmonary artery, 50 patients with transposition of the great arteries (TGA) type of DORV and 7 patients with remote ventricular septal defect (VSD) type underwent IVR plus arterial switch operation and 6 patients with TGA type and 5 patients with remote VSD type underwent IVR plus double-root translocation. There were three hospital deaths and one late death (overall operative mortality: 1.5%).

CONCLUSION

Preoperative echocardiography provided crucial data to estimate the feasibility of intraventricular tunnel creation to either the aorta or the pulmonary artery and to guide the selection of either arterial switch or double-root translocation. Biventricular repair could be achieved with favorable outcomes in most patients with DORV.

[Cyanosis in a calf with a double outlet right ventricle]

A 4-day-old female Holstein Friesian calf was presented for evaluation of cyanosis and dyspnea. On auscultation, severe bronchovesicular sounds and a systolic heart murmur of grade IV/VI above the tricuspid valve were found. On echocardiography, a marked dextroposition of the aorta (> 50% originating from the right ventricle), leading to both great arteries arising from the right ventricle - a so-called double-outlet right ventricle - was detected. Two ventricular septal defects were present, one in the perimembranous, subpulmonary region, the other non-committed in the muscular region. The subpulmonary ventricular septal defect was responsible for the shunting of unoxygenated blood into the aorta. Additionally, an aneurysma-like atrial septal defect (type secundum) and a large patent ductus arteriosus were visualized. The main pulmonary artery was severely enlarged without the presence of a stenotic defect. The findings could be verified by angiography. Additionally, a diffuse hypoplastic ascending aorta was visualized. Necropsy confirmed the echocardiographic and angiographic findings.

Echocardiographic Classification and Surgical Approaches to Double-Outlet Right Ventricle for Great Arteries Arising Almost Exclusively from the Right Ventricle

Selecting an appropriate surgical approach for double-outlet right ventricle (DORV), a complex congenital cardiac malformation with many anatomic variations, is difficult. Therefore, we determined the feasibility of using an echocardiographic classification system, which describes the anatomic variations in more precise terms than the current system does, to determine whether it could help direct surgical plans. Our system includes 8 DORV subtypes, categorized according to 3 factors: the relative positions of the great arteries (normal or abnormal), the relationship between the great arteries and the ventricular septal defect (committed or noncommitted), and the presence or absence of right ventricular outflow tract obstruction (RVOTO). Surgical approaches in 407 patients were based on their DORV subtype, as determined by echocardiography. We found that the optimal surgical management of patients classified as normal/committed/no RVOTO, normal/committed/RVOTO, and abnormal/committed/no RVOTO was, respectively, like that for patients with large ventricular septal defects, tetralogy of Fallot, and transposition of the great arteries without RVOTO. Patients with abnormal/committed/RVOTO anatomy and those with abnormal/noncommitted/RVOTO anatomy underwent intraventricular repair and double-root translocation. For patients with other types of DORV, choosing the appropriate surgical approach and biventricular repair techniques was more complex. We think that our classification system accurately groups DORV patients and enables surgeons to select the best approach for each patient's cardiac anatomy.

The trabecula septomarginalis (Leonardo's cord) in abnormal ventriculo-arterial connections: anatomic and morphogenetic implications

Background

The abnormal ventriculo-arterial connections in atrio-ventricular concordance and situs solitus with two well developed ventricles include the range from tetralogy of Fallot throughout the different forms of double outlet right ventricle to transposition of great arteries.

The infundibular septum and the trabecula septomarginalis are the fundamental anatomical landmarks for the segmental analysis.

In these abnormalities there is a pathological progressive counter-clockwise rotation of the infundibular septum which divorces from the antero-superior limb of the trabecula septomarginalis and achieves his identity. Is there any anatomical evidence of a simultaneous abnormal counter-clockwise rotation of the trabecula septomarginalis?

Methods

Malposition of great arteries is a generic term since all relationships have to be expected.

We present specimens with anatomical evidence of a progressive counter-clockwise rotation from 0° to about 180°of the plane passing throughout the trabecula septomarginalis’s limbs.

Results

We can observe sequentially:

1. Malformations in which the posterior limb of the trabecula septomarginalis is committed to the ventriculo infundibular fold: (tetralogy of Fallot, double outlet right ventricle with sub-aortic ventricular septal defect, truncus arteriosus and doubly committed ventricular septal defect);

2. Malformations in which the posterior limb of the trabecula septomarginalis is committed to the infundibular septum (double outlet right ventricle with sub-pulmonary ventricular septal defect, transposition of great arteries).

Conclusions

1. The sequential-segmental analysis identify all the morphologies.

2. The trabecula septomarginalis plane presents a progressive counter-clockwise twist on the long axis.

3. Since the trabeculated portions of the ventricles are the oldest developmental components, our observations support the hypothesis that the abnormal ventriculo-arterial connections could be in relation with a pathological myocardial process during early cardio-genesis.

We are promoting new studies to investigate our anatomical observations.