Pulmonary venous ectopic drainage, also known as pulmonary venous malformation drainage or pulmonary venous malformation connection, refers to one or all branches of the pulmonary veins that are not connected to the left atrium, and blood from the pulmonary circulation cannot flow into the left atrium, but flows back to the right atrium directly or indirectly through the venous system of the body circulation. There are two types of pulmonary venous ectopic drainage: complete and partial, often combined with atrial septal defect, patent foramen ovale, or other cardiovascular malformations.
Complete pulmonary venous ectopic drainage is defined as the ectopic connection of all pulmonary veins to the right atrium or to the veins introducing the right atrium, without connection to the left atrium. It can be combined with atrial septal defect (about 25%) or patent foramen ovale (about 75%). It is one of the four major cyanotic heart diseases in infants and children.
(A) Pathophysiology
It is characterized by the formation of a bidirectional shunt in the right atrium. The factors affecting the bidirectional shunt include the obstruction of the anomalous connection, the size of the atrial septal defect and the combination of other cardiac malformations, etc. Ultimately, it depends entirely on the degree of venous mixing between the body and pulmonary circulation in the right atrium, and the severity of the patient’s clinical symptoms also depends on these factors. If there is no obstruction of the ectopic pulmonary venous connection and the atrial septal defect is large enough, the oxygen saturation of the four chambers of the heart is the same, and the oxygen saturation of the arteries of the body circulation is only mildly decreased, and there may be no cyanosis or only mild cyanosis in the clinic. If the interatrial traffic is small, cyanosis may be evident clinically. In addition, in some cases, pulmonary hypertension and even right ventricular failure may develop.
(II) Diagnostic points
The clinical symptoms are related to the degree and nature of pulmonary hypertension, which mainly include shortness of breath, cyanosis, right heart enlargement and congestive right heart failure. If there is pulmonary hypertension or pulmonary vein stenosis, cyanosis is obvious and pulmonary edema occurs repeatedly. On the contrary, those who do not have pulmonary hypertension or pulmonary vein stenosis, cyanosis appears relatively later and lighter.
2. Signs Cyanosis, enlarged heart, fixed 2nd heart sound split and increased pulmonary blood on X-ray chest film are called tetralogy of complete pulmonary vein ectopic connection. The signs of this disease are characterized by.
(i) cyanosis with pestle-like fingers (toes).
(ii) Large liver.
(iii) Heart murmur similar to atrial septal defect, systolic murmur can be heard at the 2nd-3rd intercostal space on the left edge of the sternum, with hyperactive splitting of P2.
④continuous murmur can be heard in the left upper chest, which is produced by blood flow through ectopic pulmonary veins.
3.Auxiliary examination
The diagnosis is mainly confirmed by echocardiography and right heart catheterization.
(C) Indications and contraindications for surgery
1.Surgical indications and timing
(1) Complete pulmonary venous ectopic drainage should be diagnosed as soon as possible after birth, and once pulmonary venous return obstruction is found, surgery should be performed immediately.
(2) If there is no pulmonary venous return obstruction but pulmonary hypertension, early surgery is required; if there is no pulmonary venous return obstruction and no pulmonary hypertension, surgery should be performed within 5 years of age at an opportune time.
(3) Pulmonary hypertension and rising whole lung resistance in the neonatal period are not contraindications to surgery.
2. Contraindications to surgery
A. Complex congenital heart malformation that cannot be repaired; B. Total pulmonary resistance/body circulatory resistance 0.75.
(D) Prognosis
The prognosis for complete pulmonary venous ectopic drainage is extremely poor, with 80% of deaths occurring within 1 year of age. The surgical mortality rate of this disease varies significantly, and in the cases summarized by Oelert, it is as high as 42% for the subcardiac type, 14% for the supracardiac type, and 11% for the intracardiac type. The most important factor affecting the outcome of surgical treatment is the pulmonary hypertension caused by obstruction of the common pulmonary vein.