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Syndrome of hypoplasia of the left heart
Last reviewed: 23.04.2024
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The hypoplasia syndrome of the left heart consists of left ventricular hypoplasia and ascending aorta, underdevelopment of aortic and mitral valves, atrial septal defect and wide open arterial duct. If the physiological closure of the arterial duct is not prevented by the infusion of prostaglandin, cardiogenic shock will develop and the child will die. Often a loud single tone II and nonspecific systolic noise are heard. Diagnosis is based on emergency echocardiography or cardiac catheterization. Radical treatment - stage-by-stage surgical correction or heart transplantation. It is recommended to prevent endocarditis.
The hypoplasia syndrome of the left heart is 1% among congenital heart defects. Oxygenated blood returning to the left atrium from the lungs can not enter the hypoplastic left ventricle. Instead, the blood through the interatrial communication enters the right heart, where it mixes with venous neoxigenic blood. This relatively non-oxygenated blood exits from the right ventricle and through the pulmonary arteries enters the lungs, and also through the arterial duct - into the large circle of blood circulation. A large circle of blood circulation receives blood only through right-left blood discharge through the arterial duct; so the prognosis for life immediately after birth depends on the preservation of the open arterial duct.
Symptoms of left heart hypoplasia syndrome
Symptoms occur when the arterial duct begins to close during the first 24-48 hours of life. Further symptoms of cardiogenic shock develop (for example, tachypnea, dyspnea, weak pulse, cyanosis, hypothermia, pallor, metabolic acidosis, drowsiness, oliguria and anuria). When the systemic circulation is disturbed, the perfusion of cerebral vessels and coronary vessels can be reduced, which leads to the appearance of symptoms of myocardial ischemia or brain. If the arterial duct can not be reopened, death quickly begins.
In physical examination, vasoconstriction of the vessels of the extremities and a gray coat of the skin are revealed (due to cyanosis and hypoperfusion). II tone is loud and single. Sometimes a soft nonspecific noise is heard. Characteristically, heavy metabolic acidosis is disproportionate to Po and PCo.
Diagnosis of left heart hypoplasia syndrome
The diagnosis is based on clinical data and is confirmed in two-dimensional echocardiography with color Dopplercardiography. Cardiac catheterization is usually necessary to clarify the anatomy of the blemish before surgery.
On the roentgenogram, cardiomegaly and venous congestion in the lungs or pulmonary edema are detected. On the ECG, almost always detect hypertrophy of the right ventricle.
[Treatment of left heart hypoplasia syndrome
All children should be immediately placed in the intensive care unit of newborns. Vascular access should be provided, usually through the umbilical venous catheter; then an infusion of prostaglandin E1 [PGE1; the initial dose of 0.05-0.1 μg / (kg x min) IV) in order to prevent the closure of the arterial duct or reopen it. As a rule, newborns should undergo intubation of the trachea and begin artificial ventilation. Metabolic acidosis is corrected by infusion of sodium bicarbonate. Newborns in serious condition with cardiogenic shock may require the appointment of inotropes and diuretics to improve cardiac function and control the volume of circulating blood.
In the future, newborns require a phased correction, after which the right ventricle begins to function as a systemic one. The first stage - the Norwood operation - is conducted in the first week of life. The pulmonary trunk is separated, the distal branch is covered with a patch and ligated with an arterial duct. Then, a right-sided shunting through Blalock-Taussig or the formation of a channel between the right ventricle and the pulmonary artery (Sano modification) is performed; the interatrial septum increases, and the proximal pulmonary artery and the hypoplastic aorta are connected to the aortic or pulmonary artery allograft to form a new aorta. Stage 2, which is performed after 6 months, consists of a bi-directional bypass surgery - Glenn surgery (anastomosis end in the side between the superior vena cava and right pulmonary artery) or hemi-Fontan surgery (see "tricuspid valve atresia"). The third stage, which occurs approximately 12 months after the 2nd, includes a modified Fontan operation; blood from the inferior vena cava is directed to the pulmonary circulation, completely bypassing the right ventricle. Survival is 75% after the first stage, 95% after the second, 90% after the third stage. 5-year survival after surgical correction is 70%. Many patients develop disability, associated with a violation of neuropsychic development, which, most likely, may be a consequence of previous anomalies of the central nervous system, rather than surgery.
In some centers, heart transplantation is the method of choice; at the same time, the infusion of prostaglandin E1 should be continued until the moment when the presence of the donor heart is known. Also, the availability of donor hearts is very limited; about 20% of newborns die, waiting for a donor heart. 5-year survival after cardiac transplantation and after a multi-stage correction is approximately the same. After heart transplantation, the appointment of immunosuppressants is necessary. These drugs make patients more susceptible to infections and after 5 years cause pathological changes in the coronary arteries of the graft in more than 50% of patients. The only known way to treat coronary artery disease of a transplant is repeated transplantation.
All patients should receive endocarditis prophylaxis before dental or surgical procedures in which bacteraemia may develop.