Pulmonary Stenosis

Seoul National University Hospital

Department of Thoracic & Cardiovascular Surgery

Pulmonary Stenosis and Intact Ventricular Septum

1. Definition A form of right ventricular outflow tract obstruction in which stenosis is usually valvar or infundibular, or both ( rarely, supravalvar ) * Simple, pure, isolated pulmonary valvar stenosis(70%) * Pulmonary stenosis with normal aortic root 2. History Doyen : 1st attempt of surgical relief in 1913 Sellors : Closed transventricular instrumental valvotom

y repair in 1947 Brock : Closed valvotomy in 1948 Swan : Open correction during circulatory arrest in 1952 Kan : Percutaneous balloon valvuloplasty in 1982

Pulmonary Stenosis and Intact Ventricular Septum

Pathophysiology • Usually involves a stenotic valve that obst

ructs right ventricular empting and pulmonary blood flow, producing right ventricular hypertrophy and cyanosis.

• Subvalvar and supravalvar stenosis are other forms of this defect.

Pulmonary Stenosis and Intact Ventricular Septum

Patterns of pulmonary stenosis 1. Critical valvar pulmonary stenosis in neonates 2. Pulmonary stenosis in infants, children, & adults

Critical PS in Neonates

1. Pulmonary valve Uniform fibrous cone Pulmonary valve dysplasia 2. Pulmonary arteries Hypoplastic in 50% 3. Right ventricle Mild to moderately reduced Rarely severely reduced Concentric ventricular hypertrophy Diffuse fibrosis

4. Tricuspid valve Normal dimension in 50% Severe hypoplasia in 10% 5. RV-Coronary A. fistulae 2% have fistulae 10% have sinusoids 6. Right atrium Usually large, at least PFO 7. Coexisting cardiac diseases Uncommon Ebstein anomaly in 1%

Morphology

Clinical Features & Diagnosis

Critical PS in Neonates 1. Critically ill, irritable, tachypneic, hypoxic

2. Tachycardia & heart failure, tricuspid insufficiency

may be present

3. Chest X-Ray, EKG show less evidence

4. Echocardiography, cardiac catheterization,

cineangiography provide precise information.

5. Tricuspid valve is competent in 10% & the other

90% show incompetence.

Critical PS in Neonate

Natural History

1. Presentation is nearly always within 1st 2 weeks of life.

2. All neonates in whom severe hypoxia develops die

without treatment, although some may live for a few

months.

Critical PS in Neonate

Operation for Critical PS 1. Percutaneous balloon valvotomy 2. Open pulmonary valvotomy using CPB 3. Transannular patch 4. Systemic-pulmonary artery shunt 3.5 - 4.0mm PTFE graft in case of PaO2 less than 30mmHg after CPB

Critical PS in Neonate

Special features of postoperative care 1. PGE1 intravenously preoperatively and early postoperatively to maintain ductal patency 2. Infants should be restudied at 6-12 months of age if systemic-pulmonary artery shunt has been performed . 3. In about 10% of patients, follow-up evaluation indicates important residual right ventricular hypertension.

Critical PS in Neonate

1. Survival

Early death ; less than 10%

Time-related survival

2. Modes of death

Hypoxia

Acute cardiac failure

3. Incremental risk factors

for premature death

RV enlargement

(cardiomyopathy)

Reduction of cavity size

without shunt

4. Reintervention

5. Residual RVOTO

6. Morphologic & functional

changes after valvotomy

RV cavity is normal or mildly

reduced in 90%.

More than 80% of patients ;

no tricuspid incompetence

Surgical Results

PS - membranous

PS

PS with Post-stenotic Dilatation

PS

Critical PS in Neonate

Indications for operation 1. Interventional treatment is indicated for all neonates.

2. Severe hypoplasia of the pulmonary annulus ( z < -4)

& severe reduction of RV cavity size; a transannular

patch & concomitant systemic-pulmonary artery shunt

are indicated in 10-20% of patients as initial procedure.

3. In patients who fail to develop adequate oxygen level

(more than 85% ) & RA pressure (less than 12-15mmHg)

at rest with atrial septum and shunt temporally closed,

Fontan operation is ultimately indicated.

PS in Infants, Children, Adults

1. Pulmonary valve Better developed than in neonates Commissural fusion ; deformed, thickened, myxomatous, Secondary infundibular stenosis in older patients

2. Pulmonary artery Poststenotic dilatation in 70%

3. Right ventricle Uncommon hypoplasia Thickening of RV wall 10-20% have only infundibular stenosis

4. Tricuspid valve Usually morphologically normal

5. Right atrium Wall is hypertrophied Patent foramem ovale in most

6. Left ventricle Idiopathic hypertrophic subaortic stenosis (Noonan syndrome) Altered left ventricular geometry affect ventricular function (revert to normal after correction)

7. Associated anomalies Noonan’s syndrome Intrauterine rubella Neurofibromatosis

Morphology

Clinical Features & Diagnosis

1. Symptoms Symptomatic, but less severe than neonates 30-40% are asymptomatic. Effort dyspnea & cyanosis may appear.

2. Signs Systolic murmur with a thrill Pulmonary component of second sound is decreased.

3. Electrocardiography RAE, RAD, RVH T- waves in right precordial lead

4. Echocardiography, catheterization & cineangiography

PS in Infants, Children, Adults

Pulmonary Stenosis with IVS

Natural History 1. Incidence 8~10% of CHD Slightly predominance of females 2. Patients presenting in infancy Wide variation of obstruction (mild stenosis in 40%, moderate 47%. Severe 14%) 3. Patients presenting after infancy Pressure gradient less than 25mmHg rarely progress. 4. Effect of right ventricular hypoplasia 14% of PS have varying degree of hypoplasia & left untreated, affect unfavorably

Techniques of Operation

1. Comment Percutaneous balloon valvotomy is treatment of

choice for valvar pulmonary stenosis, if not possible,

open surgical valvotomy is indicated.

2. Open operation during CPB Pulmonary valvotomy

Infundibular resection

Transanular patch

PS in Infants, Children, Adults

Techniques of Operation

Valvar PS ; Operative View( Dysplastic leaflets with commissural fusion )

Special Features & Postoperative Care

1. Withdrawl pressure tracing 24 hrs after operation 2. Known tendency for infundibular hypertrophy to regress with time 3. When the RV is severely hypoplastic, symptoms and signs are substantially altered, and when they appear they tend to progress more rapidly. 4. Pulmonary stenosis with RV hypoplasia is associated with less than the expected degree of RV hypertrophy. 5. Balloon valvotomy may not be as effective, & surgical approach may be required in RV hypoplasia group.

PS in Infants, Children, Adults

Indications for Operation of PS

1. When patients first show signs & symptoms, at one or more months of age, pulmonary valvotomy is advisable. 2. Intervention is advised in asymptomqatic infants with severe stenosis. 3. In those with moderate stenosis, intervention is debatable, when stenosis is mild, not recommended. 4. In older patients, management differs only in the group with moderate stenosis. 5. The presence and degrees of RV hypoplasia are taken into account when deciding upon intervention.

PS in Infants, Children, Adults

Surgical Results of PS with IVS

1. Survival Early deaths ; near zero RV hypoplasia Advanced chronic CHF Time-related survival 2. Complete relief of PS 3. Reoperations 4. Cyanosis When PFO or residual ASD with impaired compliance, & hypoplastic RV

5. Pulmonary incompetence

6. Morphologic changes

RV enlarges and becomes

normal size in most

Tricuspid incompetence is

usually absent late postop.

7. Functional Capacity

Excellent late result

Inferior in hypoplasic ventricle

Persistent, recurrent RV failure

PS in Infants, Children, Adults