DacronŽ A synthetic material often used to fashion conduits and other prosthetic devices for the surgical palliation or repair of congenital heart disease.

Damus-Kaye-Stansel operation A procedure reserved for patients with abnormal ventriculo-arterial connections who are not suitable for an arterial switch operation (e.g. TGA and non-suitable coronary patterns, DORV with severe subaortic stenosis). The operation involves anastomosis of the proximal end of the transected main pulmonary artery in an end-to-side fashion to the ascending aorta to provide blood flow from the systemic ventricle to the aorta; coronary arteries are not translocated and are perfused in a retrograde fashion. The aortic orifice and a VSD (if present) are closed with a patch. A conduit between the right ventricle and the distal pulmonary artery provides venous blood to the lungs. The procedure was described in 1975. (Damus PS. Correspondence. Ann Thorac Surg 1975;20:724-725.) (Kaye MP. Anatomic correction of transposition of the great arteries. Mayo Clin Proc 1975;50:638-640.) (Stansel HC Jr. A new operation for d-loop transposition of the great vessels. Ann Thorac Surg 1975;19:565-567.)

David operation A surgical procedure for ascending aortic aneurysm, involving replacement of the ascending aorta with a synthetic tube and remodelling of the aortic root so the preserved aortic valve is no longer regurgitant (David TE, Feindel CM. An aortic valve sparing operation for patients with aortic incompetence and aneurysm of the ascending aorta. J Thorac Cardiovasc Surg 1992;103:617-621.)

dextrocardia Cardiac apex directed to the right of the midline. see cardiac position.

dextroposition Rightward shift of the heart. see cardiac position.

dextroversion An old term for dextrocardia. see cardiac position.

differential hypoxemia; differential cyanosis A difference in the degree of hypoxemia/cyanosis in different extremities as a result of the site of a right to left shunt. The most common situation is of greater hypoxemia/cyanosis in feet and sometimes left hand, as compared to right hand and head, in a patient with an Eisenmenger PDA.

diGeorge syndrome An autosomal dominant syndrome now known to be part of "CATCH-22". As originally described, it consisted of infantile hypocalcemia, immunodeficiency due to thymic hypoplasia, and a cono-truncal cardiac abnormality. see also CATCH-22.

discordant atrio-ventricular connections Anomalous connection of atria and ventricles such that the morphologic right atrium connects via a mitral valve to a morphologic left ventricle, while the morphologic left atrium connects via a tricuspid valve to a morphologic right ventricle.

discordant ventriculo-arterial connections Anomalous connection of the great arteries and ventricles such that the pulmonary trunk arises from the left ventricle and the aorta arises from the right ventricle.

diverticulum of Kommerell Enlarged origin of the left subclavian artery associated with right aortic arch. Its diameter may be equal to that of the descending aorta and tapers to the left subclavian diameter. It is found at the origin of the aberrant left subclavian artery, the fourth branch off the right aortic arch.

double aortic arch see aortic arch anomaly.

double-chambered RV Separation of the right ventricle into a higher-pressure inflow chamber, and a lower pressure infundibular chamber, the separation usually being produced by hypertrophy of the "septomarginal band". When a VSD is present, it usually communicates with the high pressure RV inflow chamber.

double discordance see congenitally corrected transposition of the great arteries.

double inlet left ventricle (DILV) see univentricular connection.

double orifice mitral valve The mitral valve orifice is partially or completely divided into two parts by a fibrous bridge of tissue. Both orifices enter the left ventricle. Mitral regurgitation and/or mitral stenosis may be present. Aortic coarctation and atrioventricular septal defect are commonly associated defects.

double outlet left ventricle (DOLV) Both the pulmonary artery and the aorta arise predominantly from the morphologic left ventricle. DOLV is rare, and much less frequent than double outlet right ventricle (DORV).

double outlet right ventricle (DORV) Both great arteries arise predominantly from the morphologic right ventricle; there is usually no fibrous continuity between the semilunar and the A-V valves; a ventricular septal defect is present. When the VSD is in the subaortic position without RV outflow tract obstruction, the physiology simulates a simple VSD. With RV outflow tract obstruction, the physiology simulates tetralogy of Fallot. When the VSD is in the subpulmonary position (the Taussig-Bing anomaly) the physiology simulates complete transposition of the great arteries with VSD. see also Taussig-Bing anomaly.

double switch procedure An operation used in patients with l-transposition of the great arteries (l-TGA; congenitally corrected transposition of the great arteries; cc-TGA) and also in patients who have had a prior Mustard or Senning atrial switch operation for complete transposition of the great arteries (d-TGA). It leads to anatomic correction of the ventricle to great artery relationships such that the left ventricle supports the systemic circulation. It includes an arterial switch procedure (see Jatene operation) in all cases, as well as an atrial switch procedure (Mustard or Senning) in the case of l-TGA, or reversal of the previously done Mustard or Senning procedure in the case of d-TGA.

doubly-committed VSD see ventricular septal defect.

Down syndrome The most common malformation caused by trisomy 21. Most of the patients (95%) have complete trisomy of chromosome 21; some have translocation or mosaic forms. The phenotype is diagnostic (short stature, characteristic facial appearance, mental retardation, brachydactyly, atlanto-axial instability, thyroid and white blood cell disorders). Congenital heart defects are frequent, atrioventricular septal defect and ventricular septal defect being the most common. Mitral valve prolapse and aortic regurgitation may be present. Down syndrome patients are prone to earlier and more severe pulmonary vascular disease than might otherwise expected as a consequence of the lesions identified.

dural ectasia Expansion of the dural sac in the lumbo-sacral area, seen on CT or MRI. It is one of the criteria used to confirm the diagnosis of Marfan syndrome. (Pyeritz RE et al. Dural ectasia is a common feature of the Marfan syndrome Am J Hum Genet 1988;43:726-732.) (Fattori R et al. Importance of dural ectasia in phenotypic assessment of Marfan's syndrome. Lancet 1999;354:910-913.)