Pulmonary valve stenosis

Congenital obstruction of the right ventricular outflow is usually due to pulmonary valve stenosis, but may also be intracavitary or supravalvar with involvement of the main and branch pulmonary arteries. The pulmonary valve is located between right ventricle and pulmonary artery and allows the flow of blood from the ventricle to the artery but prevent it from flowing back in the ventricle.



-Fig 5.1
Pulmonary valve stenosis. The spread of the valve is reduced e causes an obstruction for the blood flow-.
Superior Vena Cava
Aorta
Pulmonary Artery
Pulmonary Veins Pulmonary Veins
Left Atrium
Right Atrium
Left Ventricle
Right Ventricle
Inferior Vena Cava


Pulmonary stenosis with and without other associated lesions, occurs in 25% to 30% of patients with congenital heart disease. Isolated pulmonary valve stenosis is found in 80% to 90% of patients with right ventricular outflow obstruction and count for about 8-10% of congenital heart diseases. Generally patients with valvar pulmonary stenosis are asymptomatic, and the diagnosis is made when a pathologic murmur is detected on routine examination. Symptoms are rarely present in childhood but become more common with increasing age in patients with moderate to severe stenosis and consist with exertional dyspnea and fatigue due to inability of the right ventricle to increase its output in response to exertion. Children with valvar pulmonary stenosis usually exhibit normal growth and development regardless of the severity of obstruction. Squatting is extremely rare even in patients with significant central cyanosis. If squatting is present, other diagnoses, should be sought. Infants with critical pulmonary stenosis are cyanotic at birth, and the cyanosis may be severe enough to be life threatening. The stenosis of the valve determines an increase in the right ventricle pressure, The more severe the stenosis, the higher the pressure overload is and induces ventricle hypertrophy and if not relieved may conduce to heart failure. In some cases the stenosis is subvalvular, in the right ventricle just under the pulmonary valve; it is generally caused by fibromuscular tissue which stretch out in the ventricle just under the valve. Valvular and subvalvular stenosis can be associated. Pulmonary valve stenosis can be treated without surgery. In about 95% of cases it is possible to dilate the stenotic valve with catheter balloon valvuloplasty and the procedure can be performed event in neonate if required. In the other cases, included subvalvular stenosis, surgery is necessary. In cases with mild stenosis, in which the right ventricle pressure is not sufficiently high and no treatment is required, the child should be followed-up periodically to monitor right ventricle pressare and enlargment.

 

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