Marietess Tena Capili was born on December 15, 1991, at St. Boniface General Hospital to Sarah Marie Tena and Benedict Santos Capili. At birth, Marietess was diagnosed with a complex congenital heart defect. Tests showed she had:

• a double outlet right ventricle
• a hypoplastic left ventricle
• a hypoplastic mitral valve annulus (not depicted in diagram 8.1)
• a ventricular septal defect
• an atrial septal defect
• severe subpulmonary stenosis
• anomalous pulmonary venous drainage
• an interrupted inferior vena cava with azygous continuation to the right superior vena cava
• a left superior vena cava draining to the coronary sinus.

This was a very serious and complex set of heart problems. It is worth reviewing what each of these defects is and how they interacted in Marietess's case.

Both of the great arteries, the aorta and the pulmonary artery, arose from the right ventricle, giving the right ventricle two outlets. Because of the Double Outlet Right Ventricle (DORV), Marietess's aorta was connected to the right ventricle, rather than to the left ventricle. Her left ventricle was also underdeveloped or hypoplastic. Dr. Jonah Odim described Marietess as having a single ventricle or pump because the left ventricle was so small. Furthermore, the ring (or annulus) of the mitral valve connecting the left atrium to the left ventricle was underdeveloped.

There was a large VSD in the septal wall between the right and left ventricles, which was described as non-restrictive, in that the hole allowed free left-to-right shunting of blood. There was also an ASD in the septal wall between the left atrium and right atrium. This allowed blue blood to flow from the right atrium to the left atrium.

In fact, Marietess did not have a normal atrial structure, since there was an incomplete differentiation between the left and right atria. The lung drainage, instead of connecting to the left atrium, connected to the back of what amounted to a common atrial chamber. The right and left pulmonary veins brought oxygen-rich blood back to this common chamber, thus mixing the red blood with oxygen-poor blue blood.

There was a narrowing just before Marietess's pulmonary valve opening, increasing the resistance to blood flow from the right ventricle to the pulmonary arteries. In Marietess's case, this stenosis actually served to protect against congestion of the lungs.

Marietess's vena cava system was also quite unusual. In essence, the interrupted inferior vena cava meant that Marietess did not have an inferior vena cava. To compensate for the absence of this blood vessel, blood flow from the lower body came up behind the heart through the azygous vein. This vein usually connects the inferior and superior vena cavas. While Marietess did not have a functioning inferior vena cava, she had two superior vena cavas, rather than one. Blood from the azygous vein drained into the right superior vena cava and then into the common atrial chamber of Marietess's heart. The additional, left superior vena cava drained blood from the left side of her head and her left arm and entered her heart at the coronary sinus. This is the site through which blood normally drains from the heart muscle after oxygenating the heart muscle itself. As a result of the presence of the left superior vena cava, this sinus was enlarged. Thus, blood from the left SVC joined the venous return from the heart muscle and emptied into the common atrial chamber. Marietess's patent ductus arteriosus remained open on its own.

Marietess had, essentially, only one functioning ventricle: the right ventricle. All the surgical plans developed for her were designed to optimize that ventricle's pumping capacity. In addition, she had muscular obstruction below her pulmonary valve. This compromised blood flow to her lungs. Both these factors necessitated a systemic to pulmonary artery shunt (a left-modified Blalock-Taussig shunt). This shunt joined the left subclavian artery to the left pulmonary artery, to provide more pulmonary blood flow. Some blood would be ejected out of the aorta and go to the body and organs, but some blood would flow back to the pulmonary artery via the shunt to be oxygenated in the lungs and then return to the heart.

Dr. Kim Duncan treated Marietess following her birth in 1991. His initial plan for treatment was to insert a Blalock-Taussig (B-T) shunt as a palliative measure and then carry out a definitive repair when Marietess was older and stronger. When Marietess was three months of age, Duncan performed the initial palliative repair as planned. Duncan revised the B-T shunt when Marietess was six months old, to allow more blood to flow to her lungs.

Marietess continued to be seen at the Variety Children's Heart Centre. When Dr. Niels Giddins examined her on December 13, 1993, she had no specific cardio-respiratory symptoms. Her chest was clear, her peripheral pulses were good and her liver was not enlarged. While she was cyanotic and had clubbing of her fingers and toes, she did not need any medications. Her mother was told that since Duncan had left Winnipeg, it might be necessary for Marietess to undergo surgery in Saskatoon. A follow-up appointment was scheduled for early 1994.

Healthy heart

Diagram 8.1 Marietess Tena Capili - pre-operative heart 1 - Azygous vein 2 - Anomalous pulmonary venous drainage     (Right pulmonary veins draining to the right atrium) 3 - Atrial septal defect 4 - Bicuspid stenotic pulmonary valve 5 - Coronary sinus 6 - Hepatic veins draining to right atrium     instead of to inferior vena cava 7 - Azygous continuation of inferior vena cava 8 - Left Blalock-Taussig shunt 9 - Left superior vena cava 10 - Patent ductus arteriosus 11 - Anomalous pulmonary venous drainage (Left superior vena cava draining left     pulmonary veins at coronary sinus) 12 - Ventricular septal defect with overriding     aorta (Double outlet right ventricle) 13 - Hypoplastic left ventricle 14 - Severe subpulmonary stenosis