Perloff Congenital Heart Disease Reader.epub
Виталий Филимонов
The management of patients with congenital heart disease that results in congestive heart failure needs to be examined from several aspects: (a) age group, (b) rhythm, (c) volume overload, pressure overload, or cardiac muscle disease, (d) surgical sequelae, (e) pulmonary vascular disease, and (f) the consequences of chronic hypoxemia. Unlike many of the disorders in adults with acquired heart disease for which the development of congestive heart failure is necessary to warrant the risk of surgery, most congenital heart defects are corrected or palliated before the development of congestive heart failure (CHF). Thus, for many defects, prevention through surgery is the most effective management of heart failure. When CHF supervenes late in the course of the disease, the opportunity for intervention, short of transplantation, may be primarily medical.
Dr. Perloff, the founding father of the field of adult congenital heart disease, presents a decade's worth of research and clinical data in the completely redefined 3rd edition to bring you the most current information. With advances in diagnosis and treatment in children, more and more of those with CHD survive well into adulthood. Expert contributors in various fields offer a multi-disciplinary, multi-system approach to treatment so you get comprehensive coverage on all aspects of the subspecialty, including basic unoperated malformations, medical and surgical perspectives, postoperative residue, and sequelae. As someone who treats these patients, you need to be ready to provide the continual care they require.
Congenital heart disease (CHD) are structural abnormalities of the heart or intrathoracic great vessels occurring during fetal development. CHD is the most common type of birth defect and the leading cause of death in children with congenital malformations. CHD can be subdivided in non-cyanotic CHD and cyanotic CHD which is also called critical congenital heart disease (CCHD). CCHD can be further classified into 3 different types of lesions: right heart obstructive lesions, left heart obstructive lesions, and mixing lesions. This activity reviews the workup of cyanotic heart disease and describes the role of health professionals working together to manage this condition.
Objectives:
- Describe the types of cyanotic heart disease.Review the presentation of cyanotic heart disease.Summarize the treatment of cyanotic heart disease.Outline the workup of cyanotic heart disease and describes the role of health professionals working together to manage this condition.
Congenital heart disease (CHD) are structural abnormalities of the heart or intrathoracic great vessels occurring during fetal development. CHD is the most common type of birth defect and the leading cause of death in children with congenital malformations. CHD can be subdivided in non-cyanotic CHD and cyanotic CHD which is also called critical congenital heart disease (CCHD). CCHD can be further classified into 3 different type of lesions: right heart obstructive lesions, left heart obstructive lesions, and mixing lesions.[1][2][3][4]
The etiology of CHD is still largely unknown. Many cases of CHD are multifactorial and result from a combination of genetic predisposition and environmental risk factors. CCHD is usually isolated and sporadic, but it can also be associated with genetic syndromes. Approximately 15% to 20% of infants with CCHD are related to known chromosomal abnormalities, most of these are aneuploidies (trisomy 21, 13, and 18 and Turner syndrome). Potential environmental risk factors include maternal illnesses, including diabetes and phenylketonuria, maternal exposure to toxins or drugs and viral infections during pregnancy.
Congenital heart disease (CHD) affects 8 to 9 per 1000 live births, and approximately 25% are considered CCHD. The incidence of CHD increase to 2% to 6% for a second pregnancy after the birth of a child with CHD or if a parent is affected. Tetralogy of Fallot (TOF) is the most common CCHD (5% of all CCHD). Transposition of the great arteries (TGA) is the second most common CCHD (approximately 2% of all CCHD), and it is the most common CCHD manifesting in the first week after birth. It is estimated that 35% of infant deaths due to congenital malformations are related to cardiovascular anomalies.
In fetal circulation, gas exchange occurs in the placenta. From the placenta, oxygenated blood travels through the umbilical vein into the Inferior vena cava (IVC) through the ductus venosus (DV), bypassing the liver circulation. In the heart, most of the oxygenated blood is shunted from the right atrium to the left atrium through the foramen ovale (FO). From the left atrium, blood is pumped to the left ventricle and into the aorta to reach systemic circulation. A small portion of blood is pumped from the right atrium to right ventricle and the pulmonary artery. From the pulmonary artery, blood is shunted to the aorta through the ductus arteriosus (DA), bypassing the lungs. Deoxygenated blood return to the placenta by the umbilical arteries.[5][6][7]
CCHD is silent in fetal life because fetus receives oxygenated blood from the placenta and either the FO or DA can increase systemic blood flow. After DA and FO closure soon after birth, most CCHD become symptomatic. Cyanosis may be caused by persistence of fetal circulation, right-to-left shunting across the FO and ductus DA in the presence of pulmonary outflow tract obstruction or persistent pulmonary hypertension of the newborn.
The diagnosis of CCHD might be missed prenatally, or during birth hospitalization; therefore, clinicians should be aware of its clinical manifestation during the first weeks of life. History alone may be not sufficient to differentiate between congenital heart disease, pulmonary disease, an inborn error of metabolism and sepsis. Additional physical exam findings and diagnostic evaluations would be necessary to identify CCHD. Thorough family history must also be obtained giving the genetic component of CCHD.
A fetal echocardiogram should be performed in all fetuses with a suspected cardiac abnormality noted on obstetric ultrasound. Prenatal ultrasound can identify structural heart disease. However, the sensitivity of congestive heart disease detection is highly variable, depends on the operator expertise, gestational age fetal position, and type of cardiac defect.[8][9][10]
The pulse oximetry screening for CCHD in newborns was added to the Recommended Uniform Screening Panel in the United States in 2011, and it was endorsed by the American Academy of Pediatrics in 2012. Screening is performed in the well-infant nursery when the baby is at least 24 hours of age, or as late as possible if the baby is to be discharged from the hospital before 24 hours of life. Earlier screening can lead to false-positive results.
CCHD screening will only identify cardiac lesions with the right to left shunt and cyanosis. Screening is recommended in the right hand and either foot. Positive screen result includes one of the following:
Differential cyanosis, lower oxygen saturation in the lower extremities, can be seen in PPHN with interrupted aortic arch, and coarctation of the aorta. Reverse cyanosis, lower oxygen saturation in the right hand, is a manifestation of TGA with concurrent CoA or IAA. Positive pulse oximetry screen will require prompt evaluation, including 4-limb blood pressure measurement, chest radiography, ECG, and echocardiography.
The seven primary CCHD screening targets are hypoplastic left heart syndrome (HLHS), pulmonary atresia (PA), Tetralogy of Fallot (TOF), total anomalous pulmonary venous return (TAPVR), transposition of great arteries (TGA), tricuspid atresia, and truncus arteriosus. Secondary screening targets are coarctation of the aorta (CoA), interrupted aortic arch (IAA), critical aortic stenosis, DORV, Ebstein anomaly and single ventricle complex. CCHD screening would miss about 15% of all CCHD cases; COA/IAA, TAPVR and TOF cases are the most common conditions missed. A failed newborn screen may also indicate other disease processes, such as pulmonary hypertension, primary pulmonary parenchymal disease, or hemoglobinopathies.
Hyperoxia test is the initial method to distinguish CCHD from pulmonary disease. The test consists in measuring an arterial blood gas at room air and 100% inspired oxygen after 10 minutes. Neonates with congenital heart disease are usually not able to increase PaO2 above 100 mm Hg during 100% oxygen administration. In patients with pulmonary disease, PaO2 generally increased greater than or equal to 100 mm Hg with 100% oxygen as ventilation-perfusion discrepancies are overcome. A positive result indicates the cardiac origin and further cardiac workup is indicated to rule out CCHD.
Right heart obstructive lesions lead to decrease pulmonary flow. PDA supplies pulmonary blood flow by shunting blood from the aorta to the pulmonary artery. There is a right-to-left intracardiac shunt. PFO shunts deoxygenated blood from the right atrium to the left atrium, and when VSD is present, blood is shunted from the right ventricle to the left ventricle.
Positive CCHD screening with oxygen saturation less than 90% without a difference in oxygenation between upper and lower extremities. Hyperoxia test is positive in these conditions. Chest x-ray shows decreased or normal pulmonary blood flow. ECG is an important tool to differentiate among these lesions. Left axis (0 to 90 degrees) is characteristic of pulmonary atresia; left superior axis (0 to -90 degrees) for tricuspid atresia, and right axis (90 to 180 degrees) for critical pulmonary stenosis and TOF.
Left heart obstructive lesions lead to decreased systemic flow. PDA supplies systemic blood flow by shunting blood from the pulmonary artery to the aorta. There is a Left-to-right intracardiac shunt with secondary pulmonary over-circulation. PFO shunts oxygenated blood from the left atrium to the right atrium, and when VSD is present, blood is shunted from the left ventricle to the right ventricle.
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