About pulmonary valve stenosis, you should know these

In daily life, many people think that pulmonary valvular stenosis is what people often call heart disease. In fact, there is still a difference between the two, but pulmonary valvular stenosis is indeed the biggest factor causing heart disease. The severity of pulmonary valve stenosis varies at different ages. If you want to thoroughly understand this disease, you must know about its pathological anatomy, pathophysiology, main symptoms, related examinations and surgical indications. Only after understanding these can people better prevent the disease, and patients can also better detect and treat the disease in time to recover their health as soon as possible.

1. Pathological anatomy of pulmonary valve stenosis:

The junction of the three leaflets of the pulmonary valve adheres to each other, limiting its opening and causing valvular stenosis, which is the most common type of valvular stenosis in clinical practice. A valve with only two junctions and adhesions is called bivalve stenosis, which is less common in clinical practice. A valve with only a small hole in the center and no junction is called single valve stenosis, which is extremely rare in clinical practice.

The severity of the valvular orifice stenosis varies, generally 2-4 mm. Some cases are accompanied by valvular ring stenosis, usually with pulmonary artery stenosis and dilatation. Right ventricular infundibulum stenosis is mostly muscular stenosis, which can be circular or semi-circular. A few are membranous stenosis, and membranous stenosis often leads to the formation of a third ventricle. Pulmonary trunk stenosis may affect part or all of the common pulmonary artery, or it may extend to the left or right branches and be called pulmonary artery coarctation. Due to the obstruction of right ventricular outflow, the right ventricle often shows concentric hypertrophy, the ventricular cavity becomes smaller, and may expand in the late stage.

2. Pathophysiology

The normal pulmonary artery orifice area is 2cm2/m2 of body surface area, and that of a newborn is approximately 0.5cm2/m2 of body surface area. Patients with mild pulmonary valve stenosis often have no obvious hemodynamic changes. Usually, when it affects cardiac function, the stenosis has reached more than 60% of the pulmonary valve orifice. At this time, right ventricular blood discharge is significantly obstructed, right ventricular pressure increases, while pulmonary artery pressure is normal or lower than normal. The pressure difference between the two is usually between 33 and 31.92 kPa. Long-term excessive afterload on the right heart causes right ventricular hypertrophy or even failure, and increases right atrial and venous pressure, resulting in obstruction of venous return. The right ventricle is blocked from pumping blood, the right ventricular pressure increases, and the pulmonary artery pressure decreases.

3. Main symptoms:

Patients with mild stenosis may have no obvious symptoms, while those with moderate or severe stenosis may experience palpitations, shortness of breath, fatigue, and chest tightness after exertion. Severe patients may experience syncope, and may have corresponding symptoms if right heart failure occurs. Severely ill patients may suffer from hypoxic cardiac arrest and sudden death. If there is atrial septal defect or patent foramen ovale, there may be varying degrees of cyanosis.

4. Main signs: There is a loud, rough, jet systolic murmur in the second intercostal space on the left side of the sternum, often accompanied by thrill, the second heart sound is split and weakened, and there may be an early systolic click from the pulmonary artery; the murmur of the infundibulum type is loudest between the third and fourth intercostal spaces on the left side of the sternum, and there is no early systolic click of the pulmonary artery; the murmur of the arterial type spreads to the armpits and back.

5. Examination of pulmonary valve stenosis :

X-ray and MRI examinations showed enlarged right ventricle and low blood flow to the lungs. Valvular type: The vascular shadows at the hilum of the lung are normal, the pulmonary artery segment is obviously bulging, and the heart shadow is gourd-shaped; funnel type: The pulmonary artery segment is not bulging, and is occasionally concave; arterial type: The pulmonary artery shadow occasionally becomes smaller.

Electrocardiogram and echocardiogram: Electrocardiogram and vectorcardiogram may be normal, incomplete right bundle branch block, right ventricular hypertrophy or right ventricular hypertrophy with strain, right atrial hypertrophy, right axis deviation, and large frontal QRS vector loop

The vector can be above (+) 90°. Echocardiography showed ventricular hypertrophy, thickening of the pulmonary valve protruding toward the pulmonary artery in a dome-like shape, or ventricular outflow tract stenosis. Doppler echocardiography helps estimate the pressure difference between the anterior and posterior valve orifices.

Cardiac catheter examination: right ventricular pressure increased, pulmonary artery pressure decreased, and the pressure gradient between right ventricular systolic pressure and pulmonary artery systolic pressure exceeded 1.33 kPa (10 mmHg). The membranous type only records two pressure curves, the right ventricle and the pulmonary artery; the infundibulum type can also record a third pressure curve in the infundibulum, whose systolic pressure is the same as that of the pulmonary artery, and whose diastolic pressure is the same as that of the right ventricle.

Cardiovascular angiography: Right ventriculography shows that in the valvular type, the valve leaflets fuse during ventricular systole and protrude into the pulmonary artery like a tent, and the valve orifice is shaped like a fish's mouth, from which the contrast agent is sprayed out like a narrow strip and then spreads out in a fan-like shape; in the infundibulum type, the right ventricular outflow tract is long and narrow; in the arterial type, local stenosis of the pulmonary artery or its branches is seen.

6. Surgical indications for pulmonary valve stenosis:

(1) The patient has obvious symptoms;

(2) obvious right ventricular hypertrophy on electrocardiogram;

(3) Chest X-ray shows significant enlargement of the right ventricle;

(4) When the pressure difference between the right ventricle and the pulmonary artery is greater than 4 kPa (30 mmHg) at rest, or greater than 5.33 kPa (40 mmHg) for infants and young children;

(5) Patients with recurrent right heart failure should undergo surgery as soon as possible;

(6) Newborns with severe hypoxemia should also undergo surgery as soon as possible;

(7) Patients with other cardiac malformations that can be treated surgically;

(8) The pulmonary valve area is less than 0.5 cm2/m2 of body surface area.

Surgical treatment of pulmonary valve stenosis: incision of the stenotic valve under direct vision; removal of the hypertrophic myocardium or diaphragm in the infundibulum; removal and re-anastomosis of the stenotic pulmonary artery, or bypass grafting; balloon angioplasty may also be considered.