2Defined as congenital absence or agenesis of the tricuspid valve, with no direct communication between the right atrium and right ventricle.Incidence : 0.06 per 1000 live birthsPrevalence :in clinical series of congenital heart disease is %.
3HISTORY First reported by Kreysig in 1817. Clinical features reported by Bellet and Stewart inAlso by Taussig and Brown in 1936.
4EMBRYOLOGYDuring early embryogenesis,the process of expansion of the inlet portion of the right ventricle coincides with development of the AV valves.Failure of this process of inlet expansion is the pathogenetic mechanism for the usual muscular variety of tricuspid atresia.
5The less common variety , with well formed but fused leaflets,occurs if the embryological insult occurs later in gestation.If valve fusion is incomplete, tricuspid stenosis develops.
7ANATOMY The most common type of tricuspid atresia is muscular . It is characterized by a dimple or a localized fibrous thickening in the floor of the right atrium at the expected site of the tricuspid valve.The muscular variety constitutes 89% of cases.
9In the membranous type (6 In the membranous type (6.6%), the atrioventricular portion of the membranous septum forms the floor of the right atrium at the expected location of the tricuspid valve.This particular type appears to be associated with absent pulmonary valve leaflets.
10Minute valvar cusps are fused together in the valvar type (1%). In the Ebstein type (2.6%), fusion of the tricuspid valve leaflets occurs; attachment is displaced downward, and plastering of the leaflets to the right ventricular wall occurs.
11The atrioventricular canal type is extremely rare (0. 2%) The atrioventricular canal type is extremely rare (0.2%). -a leaflet of the common atrioventricular valve seals off the only entrance into the right ventricle.
13The right atrium is enlarged and hypertrophied. An interatrial communication is necessary for survival.This communication most commonly is a stretched patent foramen ovale.
14A true ASD is much less common and when present is almost always in the ostium secundum location. Rarely, the patent foramen ovale is obstructive and may form an aneurysm of the fossa ovalis, which is sometimes large enough to produce mitral inflow obstruction
15The left atrium may be enlarged, especially when the pulmonary blood flow is increased. The mitral valve is morphologically normal; it is rarely incompetent and has a large orifice.The left ventricle is enlarged and hypertrophied but usually morphologically normal
16The right ventricle is small and hypoplastic. In patients with a large VSD or TGA, the size of the right ventricle may be larger, but, even in these patients, the right ventricle is smaller than normal.
17VSD in tricuspid atresia Associated VSD is common with TA, seen in about 90% of individuals during infancy.Is usually perimembranous but also may occur in the muscular septum or as a component of an atrioventricular septal defect, although the latter is rare.At birth the VSD is usually restrictive,permitting adequate but not excessive pulmonary blood flow .
18This advantage is often lost, as 40% of these defects close spontaneously/ decrease in size-”acquired pulmonary atresia”The majority of defects close in the first yr of life.These restrictive VSD’S cause subpulmonic obstruction in pts with normally related great arteries, and subaortic obstruction in pts with TGA.
19ClassificationProposed by Kuhne and later modified Type 1 : normally related great arteries (70 – 80%) a. intact ventricular septum with pulmonary atresia( 9%) b. small ventricular septal defect and pulmonary stenosis( 51%) c. large ventricular septal defect without pulmonary stenosis ( 9%)
20Type ii : D-transposition of great arteries (12 – 25%) a Type ii : D-transposition of great arteries (12 – 25%) a. ventricular septal defect with pulmonary atresia( 2%) b. ventricular septal defect with pulmonary stenosis( 8%) c. ventricular septal defect without pulmonary stenosis(18%)
21Type 3 :L- Transposition or malposition of great arteries (3-6%) associated complex lesions, ie., truncus arteriosus, endocardial cushion defect
24ADDITIONAL CARDIOVASCULAR ABNORMALITIES- 20% Coarctation of aorta – 8%Persistent left SVCJuxtaposition of atrial appendages-50% of TA with TGA.Right aortic archAbnormalities of mitral apparatus- cleft in AML,malattachment of the valve,direct attachment of the mitral leaflets to papillary muscles.
25PHYSIOLOGY-TA WITH NRGA Obligatory rt to left shunt at atrial level.LA receives both the entire systemic and pulmonary venous return.The entire mixture flows into the LV which is the sole pumping chamber for the pulmonary and systemic circulation.
26When the great arteries are normally related,pulm artery blood flow is usually reduced as the restrictive VSD, is a zone of subpulmonic stenosis.LV overload is curtailed but at the cost of cyanosis.This is so in 90% of cases.
27In TGAThe VSD is almost always non-restrictive and pulmonary stenosis is usually absent.Low PVR results in abundant pulmonary arterial blood flow.Minimal cyanosis,marked LV volume overload.If these pts have a restrictive vsd,or infundibular narrowing→diminished syst circulation→metabolic acidosis and shock.
28SEX PREDILECTIONTr. Atresia with normally related great arteries have an equal frequency in males and females.If TGA is present→male preponderance.No male preponderance with juxtaposition of atrial appendages.
29GENETICSAlthough specific genetic causes of the malformation remain to be determined in humans, the FOG2 gene may be involved in the process.This has however been validated only in animal studies.Familial recurrence is low , and recurrence in siblings is only about 1%.
30OVERALL ACTUARIAL SURVIVAL IN INFANTS WITH TRICUSPID ATRESIA 1 year- 72%.5 years- 52%.10 years- 46%
31NATURAL HISTORYFew infants with tr. Atresia and normally related gr . Arteries with an intact ventricular septum survive beyond 6 months of age without surgical palliation.Intense hypoxia and death ensue unless the ductus is patent, or adequate systemic to PA collaterals are present , either of which are unlikely.
32TR. ATRESIA WITH NRGA AND SMALL VSD. The VSD in such patients closes spontaneously or is excessively obstructive, so that majority of patients die by one year.Rarely, a favorable balance is achieved b/w the presence of VSD and pulm . Blood flow , permitting survival from 2nd to 5th decades.
33TR. ATRESIA WITH NRGA AND LARGE VSD. Pts with TA , normally related great arteries and large VSD do not fare wellExcessive pulmonary arterial flow results in vol. overload of LV and CCF.Pts have lived to ages 4 to 6 years.In exceptional cases, long survivals have been reported between ages 32 and 45 yrs.
34TR. ATRESIA WITH TGASame poor longevity patterns hold when TA occurs with complete transposition and large VSD.TA with TGA with subaortic stenosis( restrictive VSD) is an ominous combination.Exceptional survivals to mid-late teens have been recorder.problems related to increased longevity-I.E,brain abscess, paradoxical embolism
35Physical examination- appearance Dysmorphic facies-occasionally “cat-eye” syndrome or congenital coloboma may be seen.
36JVPIncrease in the A wave amplitude , due to the restrictive interatrial communication.Y descent is slowIn LVF, A and V waves increase in amplitude.
37Precordium LV impulse without a RV impulse in a cyanotic patient. A gentle RV impulse in pt with TA ,complete transposition and a well dev RV .Palpable thrill if VSD is restrictive.
38AUSCULTATION First heart sound is single . Second usually single, but a soft delayed pulmonic component is occasionally present.TA with normally related great arteries, prominent systolic murmur originates at the site of restrictive VSD – holosystolic, maximal at the mid to lower left sternal edge.
39TA with complete transposition and increased pulmonary blood flow Holosystolic murmur – across VSDS2 – single but always loudS3MDM4th heart sounds are rare in any of the varieties of tricuspid atresia.
40Pulmonary vascular resistance – high VSD murmur vanishesSoft midsystolic murmur- anterior aortic rootRarely, the loud second component from the dilated hypertensive posterior pulmonary trunk is heard.
41TA with complete transposition, coexisting pulmonic or subpulmonic stenosis – midsystolic murmur – loudness and length vary inversely with degree of obstruction
42ECG Tall peaked right atrial P waves are usually seen Biatrial P – if left atrial volume is↑ due to ↑PBF.PR interval- normal.QRS axis – left and superior ( type 1 pts)Absence of RV forces in precordial leads
44CHEST X-RAY-TA WITH NRGA AND SMALL VSD Pulmonary vascularity reduced.Pulmonary artery segment – inconspicuous.Heart size – normal.Right cardiac border, esp in LAO projection – superior convexity caused by enlargement of RA and its appendage.
45Inferior border – flat or receding owing to absence of RV. LAO – Humped appearance of right cardiac border and a prominent left cardiac silhouette
53CARDIAC CATHETERIZATION Limited role at present.Therapeutic role for balloon atrial septostomy.Prior to a Fontan for determining pulm.vascular resistance.
54HEMODYNAMIC DATAIn infants, the right atrial pressure is slightly higher than the left atrial pressure.prominent ‘a ‘wave in the right atrium, especially if the interatrial communication is restrictive.LV systolic and EDP – normal.LVEDP may increase in patients with large VSD’s as PVR drops and left heart volume overload , ensues.
55INITIAL MEDICAL MANAGEMENT PGE1, should be started in neonates with severe cyanosis to maintain patency of the ductus before cardiac catheterization or planned surgeryBalloon atrial septostomy may be carried out as part of the initial catheterization to improve the RA-LA shunt.
56SURGICAL CARESurgical management may be broadly grouped into palliative and corrective therapy.
57PALLIATIVE SURGERY DECIDED IN TERMS OF decreased pulmonary flowincreased pulmonary flowintracardiac obstruction.
58FOR ↓ PBF.Pulmonary blood flow may be increased by surgical creation of an aortopulmonary shunt.subclavian artery to ipsilateral pulmonary artery anastomosis by Blalock and Taussig in 1945Potts shunt (descending aorta–to–left pulmonary artery anastomosis),Waterston-Cooley shunt (ascending aorta–to–right pulmonary artery anastomosis
59central aortopulmonary fenestration or Gore-Tex shunt, modified Blalock-Taussig shunt (Gore-Tex interposition graft between the subclavian artery and the ipsilateral pulmonary artery),Glenn shunt (superior vena cava–to–right pulmonary artery anastomosis, end-to-end),
60↑ PBFIn patients with tricuspid atresia type II , pulmonary artery banding should be performed following stabilization with anticongestive measures.
61CORRECTIVE SURGERYFontan and Kreutzer- initial description of the physiologically corrective operation for tricuspid atresiaComplete separation of the systemic and pulmonary circuits
62CHOUSSAT CRITERIAAge at operation – 4 and 15 yrs( not strictly followed nowadays)Normal sinus rhythmNormal systemic venous connectionsNormal right atrial sizeNormal pulmonary arterial mean pressure ( mean >= 15 mm Hg)
63Low pulmonary vasc resistance (4 woods units/m2) Adequate sized pulm. Arteries with diameter > 75% of aortic diameter.Normal LVEF (>60%)( rel. contraindication)Absence of MR( relative contraindication)Absence of complicating factors from prev ious surgeries
65LATE COMPLICATIONS OF FONTAN EARLY COMPLICATIONS OF FONTANLow cardiac output,heart failure or both .Persistent pleural effusion.Thrombus formation in the systemic venous pathways.Liver dysfunctionHepatomegaly and ascites.Supraventricular arrythmias.Progressive decrease in oxygen saturation( obstn. of venous pathways, leakage in intra- atrial baffle, dev of pulm av fistula.).Protein losing enteropathy