Diskussion:Alfred Blalock

Die weitergehende Ausführungen zur TOF finden sich bereits im betreffenden Hauptartikel Fallot Tetralogie und wurden daher von mir unübersetzt in die Disku verschoben. --Burkhard 13:09, 6. Jan. 2009 (CET)

thumb|right|201px|Diagram showing normal blood circulation (above) and the blood circulation on a heart suffering from ToF In the normal heart, there are four separate chambers; the two top chambers are known as atria and pump blood simultaneously into the two bottom chambers, or ventricles. Blood first enters the heart at the right atrium, which then empties blood into the right ventricle, which pumps the blood into the lungs through the pulmonary artery to get oxygen. From the lungs, the blood enters the left atrium through the pulmonary vein; the left atrium empties into the left ventricle, which pumps the blood into the aorta and from there reaches the rest of the body. Because it is responsible for getting blood to the entire body through the aorta, the left ventricle is usually the biggest and strongest chamber of the heart.

The following is a depiction of normal blood flow through the body. Valves keep the blood from flowing backwards. Capital letters indicate blood that has been oxygenated:

veins → superior or inferior vena cava → right atrium ——tricuspid valve→ right ventricle 
 ——pulmonary valve→ pulmonary artery → LUNGS → PULMONARY VEIN → 
 LEFT ATRIUM ——mitral valve→ LEFT VENTRICLE ——aortic valve→ AORTA → ARTERIES 

After the body uses up the oxygen delivered by the blood flowing through the arteries, then arterioles, then capillaries, the unoxygenated blood returns to the heart by the capillaries, then venules, then veins.

The blue baby syndrome, known as Tetralogy of Fallot (TOF), consists of an incomplete wall between the ventricles (known as a ventricular septal defect or VSD), an aorta that sits over this defect so that its blood comes from both ventricles instead of just from the left (overriding aorta), a defective right ventricular outflow tract near the pulmonary valve that prevents full flow of blood to the lungs, and a muscular right ventricle necessary to accomplish the extra work required to overcome that defect (right ventricular hypertrophy).

The following is a depiction of blood flow in Tetralogy of Fallot. Mixed capital letters indicate partially oxygenated blood.

 veins → superior or inferior vena cava → right atrium ——tricuspid valve→
    rIgHt vEnTrIcLe ——VSD→ LeFt VeNtRiClE or 
                   \__
                      ——pulmonary valve→ pulmonary artery → LUNGS → PULMONARY VEIN → 
 LEFT ATRIUM ——mitral valve→ 
    LeFt VeNtRiClE <—————————————————————————————————————————rIgHt vEnTrIcLe
                   \__
                      ——aortic valve→ aOrTa → aRtErIeS

Unoxygenated blood from the right ventricle flows into the aorta preferentially because of the obstructed outflow tract into the lungs. This means less blood has the opportunity to be oxygenated in the lungs. Blood mixes abnormally between the left and right ventricles and into the aorta. Oxygen gives blood its reddish color. Cyanosis describes the "blueness" in the baby and results from the pumping of mixed oxygenated and unoxygenated blood throughout the body.

Blalock developed the idea for the operation from his aforementioned failed experiments on dogs. The shunt joins the left subclavian artery (normally oxygenated but partially oxygenated in TOF) to the left pulmonary artery (normally unoxygenated but with very little blood flow in TOF). This increases the amount of blood that goes into the lungs and is returned to the left side of the heart. As a result, more oxygenated blood is pumped to the rest of the body. Vivien Thomas perfected the surgical technique in the laboratory and instructed Blalock during the procedure. The first Blalock-Taussig shunt operation was performed on November 29, 1944, on Eileen Saxon and instantly restored her to a healthy "pink" color. Even though this surgery only prolonged Eileen's life for two months, it was pioneering pediatric heart surgery.

Sterblichkeit Blue-Baby-Syndrom

Ein Hinweis zur Mortalität des unbehandelten Blue-Baby-Syndroms wäre für das Verständnis hilfreich. --Burkhard 13:07, 6. Jan. 2009 (CET)