Atrioventricular Canal

(AV-channel defect; defect of the endocardial cushion; ostium primum atrial defect)

The AV-channel defect consists of an atrial septal defect of the ostium primum type and a common atrioventricular valve, (ventricular channel type) with or without an associated Zulaufs- ventricular septal defect (VSD). These disorders are due to a faulty development of the endocardial cushion. Patients without a VSD component or a small VSD and with good AV valve function may be asymptomatic. If a large VSD component or a significant AV Ventilregurgitation occurs, patients often have signs of heart failure, including dyspnea with feeding, poor growth in size, tachypnea and diaphoresis. Heart murmurs, tachypnea, tachycardia, and hepatomegaly are common. The diagnosis is made by echocardiography. Treatment consists of surgical correction for all but the smallest defects.

5% of congenital heart defects are AV-channel malformations. An AV septal defect can be complete, temporarily or partially. In the complete form the inlet VSD large (non-restrictive) is. In the temporary shape of the VSD is small or moderate (restrictive). In the partial form, there is no VSD. The majority of patients with the complete form have Down syndrome. The AV channel is also common in patients with asplenia or polysplenia (heterotaxia).

The AV-channel defect consists of an atrial septal defect of the ostium primum type and a common atrioventricular valve, (ventricular channel type) with or without an associated Zulaufs- ventricular septal defect (VSD). These disorders are due to a faulty development of the endocardial cushion. Patients without a VSD component or a small VSD and with good AV valve function may be asymptomatic. If a large VSD component or a significant AV Ventilregurgitation occurs, patients often have signs of heart failure, including dyspnea with feeding, poor growth in size, tachypnea and diaphoresis. Heart murmurs, tachypnea, tachycardia, and hepatomegaly are common. The diagnosis is made by echocardiography. Treatment consists of surgical correction for all but the smallest defects. 5% of congenital heart defects are AV-channel malformations. An AV septal defect can be complete, temporarily or partially. In the complete form the inlet VSD large (non-restrictive) is. In the temporary shape of the VSD is small or moderate (restrictive). In the partial form, there is no VSD. The majority of patients with the complete form have Down syndrome. The AV channel is also common in patients with asplenia or polysplenia (heterotaxia). Complete atrioventricular septal defect comprises a complete atrioventricular canal (atrioventricular septal defect (complete form).) A large ostium primum defect (ASD with a defect in the anteroinferior portion of the septum), a non-restrictive enema VSD and an AV flap opening with an insufficiency. This defect is also referred to as a complete common AV channel. A left-right shunt occurs on atrial and ventricular level and is often large. The AV valve insufficiency may be so pronounced that a shunt between the left ventricle and the right atrium is formed. These disturbances lead to an increase in all four chambers of the heart. Hemodynamics similar to that at an ostium secundum ASD. Over time, the increased pulmonary flow, the increased pulmonary vascular resistance and the increased pulmonary artery pressure can lead to shunt reversal and Eisenmenger syndrome (Eisenmenger’s syndrome). Atrioventricular septal defect (full form). The pulmonary blood flow, all chamber volumes and often the pulmonary vascular resistance is increased. Arterial pressures are medium pressures. AO = aorta; IVC = inferior vena cava; LA = left atrium; LV = Left ventricle; PA = pulmonary artery; PV = pulmonary veins, RA = right atrium; RV = right ventricle; SVC = superior vena cava. Temporary septal A temporary septal defect consists of an ostium primum ASD; a restrictive inlet VSD, whose size can be small or moderate; and a common AV valve. This defect is referred to as transient AV channel. The shunt at the atrial level is usually great. The shunt on the ventricular level is less than a full AVSD and the right ventricular pressure is lower than the left ventricular pressure. Hemodynamics depends largely on the size of the VSD and whether a significant AV valve regurgitation is present. Atrioventricular septal defect (partial form) A partial AV valves defect consists of an ASD of the ostium primum and a division of the common AV valve in 2 separate AV openings, resulting in a so-called column of the mitral valve (left AV column). The ventricular septum is intact. Hemodynamic abnormalities similar to those of the ASD in the ostium secundum (z. B. left-right shunt at the atrial level, enlarged right heart chambers, increased pulmonary blood flow) with an additional finding of various degrees of left AV valve insufficiency. Symptoms and complaints The complete AV canal with a left-right shunt caused old at 4-6 weeks children a failure (eg. As tachypnea, dyspnea with feeding, low weight gain, diaphoresis). The increased pulmonary vascular resistance (Eisenmenger’s syndrome) is usually a late complication, but may occur earlier, especially in children with Down syndrome. The partial AV channel remains asymptomatic during childhood if mitral regurgitation is missing or low. Symptoms (eg. As fatigue during exercise, fatigue, palpitations) may develop during adolescence or early adulthood. Children with moderate or severe mitral regurgitation often show signs of heart failure. Patients with transient AV septal defects may have signs of heart failure when the VSD is only slightly restrictive, or may be asymptomatic when the VSD (small) is very restrictive. The physical examination in children with complete atrioventricular septal defects shows an active precordium by volume and pressure overload of the right ventricle; a single loud 2. heart sound (S2) on the basis of pulmonary hypertension, a grade 3-4 / 6-systolic; and sometimes a diastolic murmur at the top and at the bottom left sternal. Most children with a partial defect have a wide split S2 and a mittsystolisches (or ejection) noise at the upper left sternal. In a very large atrial shunt at the lower left sternal a mittsystolisches rumble can be heard. A gap in the AV valves shows how the apical blowing noise of a mitral regurgitation. The cardiac findings in children with a partial defect similar to those in an ostium secundum ASD (atrial septal defect (ASD)). Is an additional mitral regurgitation before, you can hear a Frühsystolikum at the apex. Diagnostic chest X-ray and ECG echocardiogram Diagnosis is suspected based on clinical examination, supported by chest x-ray and EKG and confirmed by a two-dimensional Farbechokardiographie with Doppler examination. The chest x-ray showing cardiomegaly with an enlargement of the right atrium, biventricular enlargement, a prominent pulmonary artery and increased pulmonary vascular drawing. The ECG shows an upward QRS axis (z. B. a deviation of the left or northwestern axis), often an AV block 1st degree, or a left or right ventricular hypertrophy, or both and, occasionally, a right-magnification and a right bundle branch block. The two-dimensional Farbechokardiographie and Doppler studies confirm the diagnosis and can provide valuable information on the anatomy and hemodynamics. A cardiac catheterization is usually not necessary unless the hemodynamic structures need to be further clarified before an operation (for example, the pulmonary vascular resistance in a patient who introduces himself in old age, to evaluate). Treatment Surgical correction for heart failure: drug therapy (. Eg diuretics, digoxin, ACE inhibitors) before surgery A complete atrioventricular septal defects should be cured with an age of 2-4 months, because most children suffer from heart failure and failure to thrive , Even if children thrive without significant symptoms, treatment should be done before the age of 6 months in order to prevent the development of pulmonary vascular disease, especially in children with Down syndrome. In patients with two sufficiently large ventricles and no additional defect in the large central defect is closed (a combination of ostium primum ASD and upper VSD) and reconstructs the AV valves with two separate valves. The surgical mortality was previously 5-10%. This number has been reduced in recent years to 3-4%. The surgical complications are a complete bundle branch block (3%), a remaining VSD and / or left atrioventricular valves insufficiency. The banding of the pulmonary artery is no longer recommended unless there are other anomalies before that make surgical correction for a small infant very risky. In patients with a partial failure of the surgery at an age of 1-3 years is performed electively. The mortality of the procedure should be very low. Diuretics, digoxin and ACE inhibitors can help with large shunts and heart failure preoperatively about to limit the symptoms in patients. Endocarditis prophylaxis is not necessary prior to the surgery, but rather in the first 6 months after surgery or when a residual defect near the operated site is present. Key points A artrioventrikulärer (AV) channel may be complete, temporary or incomplete; the majority of patients with the complete form have Down syndrome. A complete atrioventricular septal defect includes a large ostium primum atrial septal defect (ASD), a ventricular septal defect (VSD) and a common atrioventricular valve (often with considerable insufficiency), all in a large left-right shunt, both on the atrial and the ventricular level and result in an extension of all 4 chambers of the heart. A partial AV septal defect also includes an ASD, but the common AV flap is divided into 2 separate AV openings and there is no VSD before, resulting in an enlargement of the right chambers of the heart due to a large atrial shunts without ventricular shunt. A transient AV septal comprises an ostium primum ASD, a common atrioventricular valve and a small or moderate VSD. The complete AV canal with a left-right shunt caused at 4-6-week-old children of heart failure (HF). The symptoms of partial AV septal defects vary with the degree of mitral regurgitation; if it is light or missing, the symptoms in adolescence or early adulthood may develop, but children with moderate or severe mitral regurgitation often manifestations of heart failure. The symptoms of a transient AV septal fall depending on the size of the VSD on a spectrum. The defects are surgically repaired between the ages of 2 and 4 months ago and 1 to 3 years depending on the specific defects and the severity of symptoms.

Health Life Media Team

Leave a Reply