Mitral Atresia with Normal Aortic Root

Abstract

Mitral atresia with normal aortic root is a rare complex congenital heart defect (CHD) and constitute less than 1% of all CHDs. In this anomaly, the mitral valve is atretic, a patent foramen ovale provides egress of the left atrial blood, either a single ventricle or two ventricles with left ventricular hypoplasia are present, and the aortic valve/root are normal by definition. Clinical, roentgenographic and electrocardiographic features are non-distinctive, but echo-Doppler studies are useful in defining the anatomic and pathophysiologic components of this anomaly with rare need for other imaging studies. Treatment consists of addressing the pathophysiology resulting from defect and associated cardiac anomalies at the time of initial presentation, usually in the early infancy. These children eventually require staged total cavo-pulmonary connection (Fontan) in three stages. Discussion of each of these stages were presented. Complications are observed in-between the stages of Fontan surgery and following completion of Fontan procedure. Attempts to monitor for early detection of these complications and promptly addressing the complications are recommended.

Keywords: Fontan operation; balloon atrial septostomy; bidirectional Glenn; blalocktaussig shunt; inter-stage mortality; mitral atresia; patent foramen ovale; pulmonary artery banding; single ventricle.

Figure 1

Selected video images from modified apical four-chamber views of two babies with mitral atresia illustrating atretic mitral valves (AMV), shown by thick arrows. The left atrium (LA) and left ventricle (LV) are small while and the right ventricle (RV) is large (A). A restrictive patent foramen ovale (PFO) is shown by a thin arrow in (B). Reproduced from [7].

Figure 2

Selected video images from parasternal long axis views of two babies with mitral atresia illustrating atretic mitral valves (AMV), shown by thick arrows. A ventricular septal defect (VSD) is pointed out by a thin arrow in (B). The left ventricle (LV) is small while the right ventricle (RV) is large particularly demonstrated in (A). Reproduced from [7].

Figure 3

(A). Selected video image from subcostal echocardiographic projection of a baby with mitral atresia demonstrating a small and restrictive patent foramen ovale (PFO) (arrow). (B). Color flow Doppler illustrates color flow acceleration (arrow in (B)) across the PFO. LA, left atrium; RA, right atrium. Reproduced from [7].

Figure 4

Selected cine frames of a static balloon angioplasty procedure to enlarge a restrictive patent foramen ovale, illustrating an inflated balloon in the posterior-anterior (A) view, displaying waisting of the balloon (arrow in (A)) which was fully abolished following further inflation of the balloon (B). Modified from [7].

Figure 5

A selected cine frame from a cine-angiogram of the left atrium (LA) illustrates the position of the restricted atrial septum (arrow) and a markedly dilated pulmonary vein (PV). Sternal wires from prior surgery are seen, but not labeled. RA, right atrium. Modified from [7].

Figure 6

Selected cine image from a left atrial (LA) cine-angiogram in a left axial oblique (30° LAO and 30° cranial) view illustrating atretic mitral valve (AMV). Opacification of the coronary sinus (CS) is seen via a connecting (C) vein. Such communications, including levoatriocardinal veins [16] have been documented in the literature. Reproduced from [4].

Figure 7

(A–D): Selected cine frames while implanting the stent across a severely restrictive patent foramen ovale shown in Figure 5, illustrating the position of the stent prior to balloon inflation (A), during balloon inflation with a waist (W) of the balloon (B), and at the conclusion (C) of stent implantation. The position of the fully inflated stent (FI) before (C) and following (D) removal of the balloon is shown. Sternal wires from prior surgery are seen, but not labeled. PT, marker pigtail catheter. Modified from [4].

Figure 8

(A). Selected 2D video image from subcostal view of an echo-Doppler study of an infant with mitral atresia who had a stent implanted 1 day prior to the study (Figure 7), illustrating the position of the stent (arrow) across the atrial septum. (B). Same as (A) but with color flow mapping. Note laminar flow (arrow) within the stent suggesting non-obstructed flow across the atrial septum. LA, left atrium; RA, right atrium. Reproduced from [4].

Figure 9

(A). Selected cine-angiographic frame showing modified Blalock-Taussig (BT) shunt connecting left subclavian artery (LSA) with the pulmonary artery (PA) with a Gore-Tex grafts (GG) [30]. This cine frame shows wide-open BT shunt and excellent opacification of PA. (B). Selected cine frame form PA cine-angiogram in straight lateral projection demonstrating narrowed section of the PA produced by pulmonary artery band (PB) shown by arrow in (B) in an infant who had the PB [37]. C, catheter; LPA, left pulmonary artery; NG, nasogastric tube; PG, pigtail catheter; RPA, right pulmonary artery. Modified from [7].

Figure 10

Selected video frames obtained from suprasternal notch view showing proximal shunt–(PS) by color flow imaging (A). In a slightly different view (B), the flow from the distal shunt (DS) into right (RPA) and left (LPA) pulmonary arteries is shown. Reproduced from [38].

Figure 11

Selected echo–Doppler images demonstrating pulmonary artery band (PAB) which is narrow (2.9 mm) by two–dimensional imaging (A) and by color flow Doppler (B) and a substantial gradient (81 mmHg) by continuous wave Doppler interrogation (C). Reproduced from reference [38].

Figure 12

Selected video image from modified apical four-chamber views in a patient with mitral atresia illustrating unrestricted left to right shunt (L to R Sh) across the atrial setpal defect (arrow). Note the non–turbulent laminar flow. LA, left atrium; RA, right atrium.

Figure 13

(A). Selected video images from suprasternal notch view demonstrating bidirectional Glenn shunt. The superior vena cava (SVC) is seen to empty into the right (RPA) and left (LPA) pulmonary arteries by color flow Doppler. (B,C). Selected video frames demonstrating connection between the inferior vena cava (IVC) and the conduit (C) by two-dimensional (B) and color flow Doppler (C). The IVC–C junction is widely patent. (D,E). Selected video frames demonstrating a patent conduit (COND) by two-dimensional (D) and color flow Doppler (E). Laminar flow as seen in (E) indicates that there no obstruction within the COND. (F). Selected video frames from an apical four chamber view by two-dimensional and color flow Doppler (F) illustrating a cross-sectional view of the C and fenestration (Fen). Turbulent flow is seen across Fen. (G). Selected video frame from apical four chamber view showing the position of the Amplatzer device (D) (arrow in (G)). No residual shunt is demonstrated. Modified from [38].

Figure 14

(A). Selected cine-angiographic frame showing bidirectional Glenn shunt (Stage II of Fontan). The unobstructed blood flow from the superior vena cava (SVC) into the right (RPA) and left (LPA) pulmonary arteries is seen. (B). Selected cine frame in antero-posterior view demonstrating Stage IIIA of the Fontan procedure conveying the inferior vena caval (IVC) blood flow into the RPA and LPA via a non-valve conduit (Cond). The fenestration (Fen) is shown by the arrow in (B,C). This cine frame demonstrates occlusion of Fen with an Amplatzer device (D), pointed out by the arrow in (C) (Stage IIIB). Sternal wires from prior surgery are seen in (A–C) and were not labeled. HV, hepatic veins. Modified from [44].