134. Complex Cardiac Malformations

  1. Complex cardiac malformations involve more than one anatomic defect. Surgical treatment does not always correct the anatomic lesion, and the methods available may only be palliative with the hope of improving oxygenation
    1. TETRALOGY OF FALLOT is a classic and common group of cardiac defects thought to result from underdevelopment of the pulmonary infundibulum. The basic defect in this cardiac malformation is an unequal division of the conus arteriosus due to an anterior displacement of the aorticopulmonary septum. This results in
      1. Pulmonary stenosis or narrowing of the region of the right ventricular outflow (infundibular stenosis)
      2. Overriding aorta: the aorta arises directly above the septal defect from both ventricular cavities
      3. Hypertrophy of the right ventricle: result of high pressure on the right side
      4. Ventricular septal defect
      5. This abnormality is regarded as the most important type of malformation causing cyanosis, but compatible with life, and as a result of the teratology there is severe dyspnea (primarily) and often moderate cyanosis (secondarily). Children have a tendency to assume a crouching position in an effort to get better oxygenation
    2. PULMONARY ATRESIA: division of the truncus arteriosus is unequal and the pulmonary trunk has no lumen. Thus, there is no orifice at the level of the pulmonary valve. There is often an associated ventricular septal defect
      1. Aortic valvular stenosis: edges of the valve are usually fused to form a dome with a narrow opening (sometimes pinpoint). Often, only 2 valves fuse and we have an abnormal bicuspid valv The size of the aorta itself is usually normal
        1. Subaortic stenosis: a ring of fibrous tissue is found circling the outflow tract of the left ventricle just below the aortic valves
      2. Aortic valvular atresia: fusion of the semilunar aortic valves is complete, resulting in the absence of an aortic orific This results in
        1. Intense cyanosis
        2. Atrophy of the left ventricle
        3. Hypertrophy of the right ventricle
        4. Perfusion of the coronary arteries by the aorta
        5. Survival is possible only if it is associated with an interatrial connection, an interventricular connection, or a patent ductus arteriosus
    4. TRICUSPID ATRESIA (absence of the right atrioventricular orifice) results in
      1. Intense cyanosis
      2. Atrophy of the right ventricle
      3. Hypertrophy of the left ventricle
      4. Survival is possible only if associated with interatrial communication, interventricular communication, or a patent ductus arteriosus
  2. Abnormalities of the lymphatic system: congenital malformations are rare
    1. THERE MAY BE A DIFFUSE SWELLING of a portion of the body or an extremity due to dilatation of the primitive lymphatic channels
      1. More rarely, a diffuse cystic dilatation of channels over the entire body
    2. CYSTIC LYMPHANGIOMA OR HYGROMA: swellings in the lower third of the neck
      1. Large single or multilocular fluid-filled cavities due to a failure of the lymphatic channels to communicate, or a pinching off of the jugular lymph sac

complex cardiac malformations: image #1