Pulmonary atresia with intact ventricular septum

Pulmonary atresia and intact ventricular septum was first described in 1784 by Hunter

Robert M. Freedom- described the diversity of this malformation and emphasized the complexity of this disorder

Epidemiology

New England Regional Infant Cardiac Program identified 75 patients with this disorder- 3.1% of all infants enrolled in the study

Baltimore-Washington Infant Study defined the prevalence for this disorder as 0.083 per 1,000 live births

Levocardia, normal atrial relations, concordant atrioventricular connections, and concordant ventriculoarterial connections

Right ventricular outflow tract is imperforate.

Either membranous or muscular atresia. The ventricular septum is intact.

Pulmonary blood flow is usually mediated by a PDA

Multiple direct aortopulmonary collaterals originating from the descending thoracic aorta may be the sole sources of pulmonary arterial supply rarely.

Nonconfluent pulmonary arteries, each supplied by a patent arterial duct may also occur rarely.

Morphogenesis

Kutsche and Van Mierop theory

Pulmonary atresia with ventricular septal defect occurs earlier in cardiac morphogenesis than pulmonary atresia and intact ventricular septum.

Pulmonary atresia and ventricular septal defect occur early in cardiac morphogenesis, after partitioning of the truncoconal part of the heart but before closure of the ventricular septum.

Pulmonary atresia and intact ventricular septum occur after cardiac septation.

Reflects a prenatal inflammatory disease rather than a true congenital malformation

Kutsche LM, Van Mierop LH. Pulmonary atresia with and without ventricular septal defect: A different etiology and pathogenesis for the atresia in the 2 types? Am J Cardiol 1983;51:932â

Few data to support an inflammatory process

Histopathological studies provided no evidence of inflammation.

Obligatory right-to-left shunt at atrial level-either a patent foramen ovale or true secundum atrial septal defect

If the interatrial septum is intact -alternative pathways for systemic venous return - coronary sinus to left atrial fenestration.

Tricuspid Valve

Ranges from extreme stenosis to severe regurgitation

Severely regurgitant valve -dilated annulus.

The valve may exhibit Ebstein anomaly.

Extremely dysplasia also seen.

Patients with the largest right ventricles usually have severe tricuspid regurgitation with valves exhibiting features of Ebstein's anomaly and dysplasia.

A major management challenge with a poor overall prognosis.

Right Ventricle

Congenital Heart Surgeons Study (CHSS)-the use of the tricuspid diameter Z value

It is the diameter of the tricuspid valve normalized to body surface area.

Data from the CHSS showed that the Z value of the tricuspid valve correlated with the size of the right ventricular cavity (p <0.0001)

Relief of outflow tract obstruction with associated pulmonary insufficiency may result in remodeling with regression of hypertrophy that can result in real or perceived growth of the right ventricle

Daubeney PE, Delany DJ, Anderson RH, et al. Pulmonary atresia with intact ventricular septum: Range of morphology in a population-based study.

J Am Coll Cardiol 2002;39:1670Freedom RM. How can something so small cause so much grief? Some thoughts about the underdeveloped right ventricle in pulmonary atresia and intact ventricular septum.

J Am Coll Cardiol 1992;19:1038

Well developed RV with hypertrophy-inlet,trabecular and outlet well developed -good prognosis.

Small RV cavity (66%)-poorer surgical outcomes

Markedly increased RV dimensions-severe TR(associated Ebsteins anomaly- 10-15 %)

The aortic arch is left sided

Aortic valve stenosis has been described in patients with pulmonary atresia and intact ventricular septum

Myocardial Abnormalities

Ischemia, fibrosis, infarction, and myocardial rupture have been observed

Myocardial disarray and ventricular endocardial fibroelastosis also seen.

Ventricular to coronary artery communications

PA IVS is associated with ventriculo arterial connections(by large sinusoids)

Usually seen in association with hypoplastic RV

Connections are seen to commonly RCA,LAD

(to LCX is rare)

Blood flow

Systole-High pressure RV to sinusoidsDiastole-coronary artery to RV- ‘coronary

steal'

Development Coronary circulation develops as isolated

plexus of vessels.

Connections first develop to ventricular cavity and later coronary arteries develop and connect to aorta.

Pulmonary atresia-high RV pressure maintains RV to sinusoids patency

Coronary artery anomalies

1) right ventricle -to-coronary artery fistulas2) coronary artery stenoses 3) coronary occlusions

Natural History Equal prevalence in male and female 50% newborns die in first month of life Majority die in first 3 months Survival beyond first year is rare. Survival upto 21 years reported.

Physical Examination Newborns with pulmonary atresia and

intact ventricular septum become cyanotic and hypoxemic –along with closure of the patent arterial duct

Cyanosis usually is apparent within hours of birth and is progressive

The left ventricle may be enlarged, and at the apex, its impulse may be forceful.

The second heart sounds is single.(A2)

A pansystolic murmur may be audible at the left lower sternal border(of tricuspid regurgitation.)

Arterial duct murmur may be heard in the second and third left intercostal space

Radiographic Features

The chest radiograph may demonstrate a heart that is only mildly enlarged or one that fills the entire chest cavity

Electrocardiographic Features

Frontal QRS axis of + 30 to + 90 paucity of right ventricular forces left ventricular dominance or left

ventricular hypertrophy Right atrial enlargement

The Electrocardiogram in Tricuspid Atresia and Pulmonary Atresia with Intact Ventricular Septum

Circulation.1966; 34: 24-37

Electrocardiograms were studied in 37 patients with tricuspid atresia and in 20 with pulmonary atresia and intact ventricular septum.

The results were correlated with

angiocardiographic findings and postmortem examinations

Biatrial hypertrophy was noted in 81% of the electrocardiograms in patients with tricuspid atresia, whereas this pattern was seen in only two infants with pulmonary atresia and intact ventricular septum

In tricuspid atresia, left axis deviation was more common.

 Pulmonary atresia - no instances of left axis deviation in the frontal plane.

Echocardiographic Features

Functional status of the interatrial septum - obligatory right-to-left shunting.

The size and morphology of the tricuspid valve ,RV

Patency of ductus

Degree of TR

Ebsteins anomaly

Functional pulmonary atresia

Lack of forward flow is due to high pulmonary artery pressure with poor right ventricular function or very severe tricuspid insufficiency.

Pulmonary valve is morphologically normal but functionally closed

Cardiac cathetrisation Groin approach Catheter passed through IVC to RA Easily passes to LA(PFO) RV entry difficult if severe TR/RV

hypoplasia Ductus visualised by left ventricular

angiogram Visualisation of coronary arteries RV angiogram-

ventricular coronary communications confirm PA

Management

• PGE1 infusion to maintain ductal patency

• Electively intubated and controlled ventilation

• Metabolic acidosis to be corrected and ionotropic support if perfusion is inadequate

• Adequately stabilized before any initial procedure

Surgical management• Goal is to achieve a two ventricular

circulation with the right ventricle providing all blood flow to the lungs at a low filling pressures without residual right to left shunt

• Goal should be achieved with • low moratality• promoting the growth of RV• minimizing the need for subsequent

surgical procedures

RV cavity size and coronary artery anatomy are crucial in selecting appropriate treatment strategy

The options available include the following.

Surgical opening of the pulmonary valve and the right ventricular outflow tract.

Systemic arterial to pulmonary arterial shunt

Transcatheter opening of the pulmonary valve.

Maintaining ductus arteriosus patency.

Systemic venous to pulmonary arterial shunt.

Closing the tricuspid valve.

Venous to pulmonary arterial shunts

Glenn procedure: end-to-end anastomosis of the SVC to the left pulmonary artery.

Cavopulmonary anastomosis or bidirectional Glenn procedure: anastomosis of the SVC to the pulmonary artery so that both lungs can be perfused by SVC blood.

Atriopulmonary connection or Fontan procedure:Anastomosis of the right atrial appendage tothe pulmonary artery to divert all venous returninto the pulmonary artery.

Severe pulmonary stenosis or pulmonary

atresia with well-developed right ventricle

and mild or no tricuspid regurgitation

Surgical pulmonary valvotomy with patch closure

Balloon valvuloplasty

Pulmonary atresia with well-developedright ventricle and marked tricuspid

regurgitation

SVC to pulmonary artery communication (bidirectional Glenn procedure) can be performed in addition to valvotomy.

Pulmonary atresia with hypoplastic right

ventricle and tricuspid valve Tricuspid valve diameter less than 8

mm in a newborn infant Tricuspid to mitral valve diameter

ratio less than 0.7 Tricuspid valve diameter Z-scores of

–3 or smaller

Management Bidirectional Glenn procedure

Pulmonary atresia with hypoplastic right

ventricle and coronary sinusoids Attempts to open the RVoutflow tract are

contraindicated.

Systemic-to-pulmonary arterial shunt or prolonged PGE1 infusion is recommended.

After the age of 3–4 months, cavopulmonary anastomosis may be performed.

Risk factor for death after initial procedure

Low birth weight Small tricuspid valve RV dependent coronary circulation

Prognosis and long-term results after

procedures Balloon valvuloplasty performed in the

neonatal period may not be very effective in relieving stenosis.

Cyanosis may persist and repeat valvuloplasty may be necessary within 6–9 months.

Residual pulmonary valve insufficiency

Pulmonary atresia with intact ventricular septum: Strategy based on right ventricular morphologyNaoki Yoshimura, MD, Masahiro Yamaguchi, MD et al J Thorac Cardiovasc Surg 2003;126

Between April 1981 and June 2002, 45 consecutive patients with pulmonary atresia with intact ventricular septum underwent surgical treatment.

Open transpulmonary valvotomy was performed in 27 patients and Blalock-Taussig shunt in 18 patients as the initial palliative procedure.

Three patients who underwent a successful transpulmonary valvotomy alone in the neonatal period required no further operation.

Definitive repair was performed in 32 patients

RESULTS There were 1 early and 2 late deaths

before the definitive operation in patients who underwent transpulmonary valvotomy.

Two patients who had coronary artery interruption died 3 months and 13 years after the initial Blalock-Taussig shunt.

There were 1 early and 2 late deaths after the definitive operation.

Survival, including noncardiac death, was 91.1% at 5 years after the initial procedure and 81.5% at 10 years

OUTCOME AFTER OPERATIONS FOR PULMONARY ATRESIA WITH INTACT VENTRICULAR SEPTUM

Jack Rychik MD, Hara Levy MD et al

J Thorac Cardiovasc Surg 1998;116

Overall  survivals at 1, 5, and 8 years were 82%, 76%, and 76%. Mortality was highest in infancy

Prenatal Diagnosis of Pulmonary Atresia with Intact Ventricular Septum

Flow through the foramen ovale- moving from the right atrium to the left atrium.

Retrograde flow through the ductus arteriosis

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