Endocardial cushion defect overview

# Overview
Endocardial cushion defects is a congenitial disorder most commonly associated with Down's syndrome. They are part of AV canal disorder resulting due to either genetic mutations or alteration in growth hormone in fetus leading to cardiac malformation during embryogenesis. Based on the anatomical features and their impact on physiology, endocardial cushion defect may be classified into complete, partial, intermediate, transitional, and intermediate forms. AV canal connects the atria to the ventricles. At four to five weeks of gestation, the superior and inferior endocardial cushions of the common AV canal fuse. Results in the formation of the mitral and tricuspid valve and the AV septum. Any failure of fusion results in endocardial cushion defect. Pathophysiology of endocardial cushion defects depends upon level of left to right shunting and degree of shunting. Incompetent AV valves in endocardial cushion defect results in regurgitation. ndocardial cushion defects are transmitted in families as an autosomal dominant. The characteristic pattern of genetic mutation has been attributed to trisomy 21 and Down syndrome. The blowing holosystolic murmur of endocardial cushion defects must be distinguished from mitral regurtitaion, tricuspid regurgitation and a ventricular septal defect. Though ECG and chest x-ray may share some common features, echocardiography can be efficiently used for an accurate diagnosis. The prevalence of endocardial cushion defect is approximately 300 to 400 per 1000,000 live births. Certain factors might increase risk of developing endocardial cushion  defect include down syndrome, rubella, alcohol consumption during pregnancy, gestational diabetes, smoking during pregnancy. Routine fetal ultrasound during prenatal care can detect endocardial cushion defects. Diagnostic findings on fetal ultrasound suggestive of endocardial cushion defect include large defect at the crux of the heart that involves the atrial and ventricular septa and a large common AV valve. If left untreated, majority of patients with endocardial cushion defect may progress to develop life threatening conditions. Common complications of endocardial cushion defect include dilatation of heart,  pulmonary hypertension, respiratory tract infections , and heart failure. Surgical mortality rate of patients with partial endocardial cushion defect is approximately 0.6%. For complete cushion defect the surgical mortality rate is 2.5-9%. Prognosis of endocardial cushion defect is generally good with treatment. However, some children might develop valvular and rhythm disorders after surgical correction. Echocardiography can be helpful in the diagnosis of endocardial cushion defect. Findings on an echocardiography diagnostic of endocardial cushion defect include diastolic movement of the mitral valve with paradoxical motion of the interventricular septum. Other findings on echocardiography include absence of the interventricular septum and right ventricular dilation. The majority of patients with endocardial cushion defect are asymptomatic. Symptoms of endocardial cushion defect include chronic upper respiratory tract infections, pneumonia, and poor growth attributable to feeding difficulties. Patients with endocardial cushion defect may have a positive history of difficulty with crying, frequent pauses during feeding and nasal flaring. Volume overload of the right side of heart can lead to right heart failure that may present with symptoms of swelling of the extremities, difficulty breathing and signs such as hepatomegaly and an elevated jugular venous pulse. On cardiovascular examinations there is a fixed splitting of second heart sound. Also, a systolic ejection murmur that is attributed to the increased flow of blood through the pulmonic valve can be heard. Patients with endocardial cushion defect may have polycythemia on CBC, which is usually due to cyanosis. Presence of a superior axis directed more towards the left is the most characterstic feature of endocardial cushion defects on electrocardiogram. Other findings on a ECG suggestive of endocardial cushion defect include prolongation of PR interval and right ventricular enlargement. The management of endocardial cushion defect depends upon the type of defect, underlying etiology and associated cardiac conditions. Surgical correction of defective valve holds the the mainstay of treatment for endocardial cushion. Medical management provides supportive care in preparing the patient for surgery. The management of endocardial cushion defect depends upon the type of defect, underlying etiology and associated cardiac conditions. Surgical correction of defective valve holds the the mainstay of treatment for endocardial cushion. Medical management provides supportive care in preparing the patient for surgery. Effective measures for the secondary prevention of endocardial cushion defects include annual cardiology evaluation, routine neurological screening, infective endocarditis prophylaxis, and risk assessment during pregnancy.

# Classification
Based on the anatomical features and their impact on physiology, endocardial cushion defect may be classified into complete, partial, intermediate, transitional, and intermediate forms.

# Pathophysiology
AV canal connects the atria to the ventricles. At four to five weeks of gestation, the superior and inferior endocardial cushions of the common AV canal fuse. Results in the formation of the mitral and tricuspid valve and the AV septum. Any failure of fusion results in endocardial cushion defect. Pathophysiology of endocardial cushion defects depends upon level of left to right shunting and degree of shunting. Incompetent AV valves in endocardial cushion defect results in regurgitation. There is a strong association between endocardial cushion defects and Down syndrome

# Causes
The most common cause of endocardial cushion defect is genetic mutations. Endocardial cushion defects are transmitted in families as an autosomal dominant. The characteristic pattern of genetic mutation has been attributed to trisomy 21 and Down syndrome.

# Differentiating Xyz from Other Diseases
The blowing holosystolic murmur of endocardial cushion defects must be distinguished from mitral regurtitaion, tricuspid regurgitation and a ventricular septal defect. Though ECG and chest x-ray may share some common features, echocardiography can be efficiently used for an accurate diagnosis.

# Epidemiology and Demographics
The prevalence of endocardial cushion defect is approximately 300 to 400 per 1000,000 live births. There is no racial predilection to endocardial cushion defects and it affects men and women equally.

# Risk Factors
There are no established risk factors for endocardial cushion defects. However, certain factors might increase risk of developing endocardial cushion  defect include down syndrome, rubella, alcohol consumption during pregnancy, gestational diabetes, smoking during pregnancy.

# Screening
Routine fetal ultrasound during prenatal care can detect endocardial cushion defects. Diagnostic findings on fetal ultrasound suggestive of endocardial cushion defect include large defect at the crux of the heart that involves the atrial and ventricular septa and a large common AV valve.

# Natural History, Complications, and Prognosis
If left untreated, majority of patients with endocardial cushion defect may progress to develop life threatening conditions. Common complications of endocardial cushion defect include dilatation of heart,  pulmonary hypertension, respiratory tract infections , and heart failure. Surgical mortality rate of patients with partial endocardial cushion defect is approximately 0.6%. For complete cushion defect the surgical mortality rate is 2.5-9%. Prognosis of endocardial cushion defect is generally good with treatment. However, some children might develop valvular and rhythm disorders after surgical correction.

# Diagnosis

## Diagnostic Study of Choice
Echocardiography can be helpful in the diagnosis of endocardial cushion defect. Findings on an echocardiography diagnostic of endocardial cushion defect include diastolic movement of the mitral valve with paradoxical motion of the interventricular septum. Other findings on echocardiography include absence of the interventricular septum and right ventricular dilation.

## History and Symptoms
The majority of patients with endocardial cushion defect are asymptomatic. Symptoms of endocardial cushion defect include chronic upper respiratory tract infections, pneumonia, and poor growth attributable to feeding difficulties. Patients with endocardial cushion defect may have a positive history of difficulty with crying, frequent pauses during feeding and nasal flaring.

## Physical Examination
Volume overload of the right side of heart can lead to right heart failure that may present with symptoms of swelling of the extremities, difficulty breathing and signs such as hepatomegaly and an elevated jugular venous pulse. On cardiovascular examinations there is a fixed splitting of second heart sound. Also, a systolic ejection murmur that is attributed to the increased flow of blood through the pulmonic valve can be heard.

## Laboratory Findings
Patients with endocardial cushion defect may have polycythemia on CBC, which is usually due to cyanosis.

## Electrocardiogram
Presence of a superior axis directed more towards the left is the most characterstic feature of endocardial cushion defects on electrocardiogram. Other findings on a ECG suggestive of endocardial cushion defect include prolongation of PR interval and right ventricular enlargement.

## X-ray
There are no x-ray findings associated with endocardial cushion defect. However, an x-ray may be helpful in the general screening of endocardial cushion defect which demonstrates cardiac enlargement and increased pulmonary vascular markings.

## Echocardiography and Ultrasound
Echocardiography can be helpful in the diagnosis of endocardial cushion defect. Findings on an echocardiography diagnostic of endocardial cushion defect include diastolic movement of the mitral valve with paradoxical motion of the interventricular septum. Other findings on echocardiography include absence of the interventricular septum and right ventricular dilation.

## CT scan
There are no CT scan findings associated with endocardial cushion defect.

## MRI
There are no MRI findings associated with endocardial cushion defect.

## Other Imaging Findings
There are no other imaging findings associated with endocardial cushion defect.

## Other Diagnostic Studies
There are no other diagnostic studies associated with endocardial cushion defect.

# Treatment

## Medical Therapy
The management of endocardial cushion defect depends upon the type of defect, underlying etiology and associated cardiac conditions. Surgical correction of defective valve holds the the mainstay of treatment for endocardial cushion. Medical management provides supportive care in preparing the patient for surgery.

## Interventions
There are no recommended therapeutic interventions for the management of endocardial cushion defects.

## Surgery
The management of endocardial cushion defect depends upon the type of defect, underlying etiology and associated cardiac conditions. Surgical correction of defective valve holds the the mainstay of treatment for endocardial cushion. Medical management provides supportive care in preparing the patient for surgery.

## Primary Prevention
There are no established measures for the primary prevention of endocardial cushion defect.

## Secondary Prevention
Effective measures for the secondary prevention of endocardial cushion defects include annual cardiology evaluation, routine neurological screening, infective endocarditis prophylaxis, and risk assessment during pregnancy.