Cardiology - Congenital Heart Disease
What is the most common congenital cardiac anomaly in adults?
Bicuspid aortic valve occurs in about 2% of the general population, is the most common congenital cardiac anomaly encountered in adult populations, and accounts for up to half of surgical cases of aortic stenosis in adults.
How is ASD diagnosed?
Cardiac ultrasonography is diagnostic and provides important prognostic information.
What is atrial septal defect (ASD)?
Classification of ASDs is based on anatomic location. Most commonly, an ostium secundum ASD occurs in the central portion of the interatrial septum as a result of an enlarged foramen ovale or excessive resorption of the septum primum.
How is ASD treated?
Closure of an ASD either percutaneously or surgically is indicated in the presence of right-sided heart enlargement, with or without symptoms. Centrally located defects measuring up to 3.5 cm can be occluded by transcatheter techniques in a cardiac catheterization laboratory.
What is the epidemiology of congenital heart disease?
Congenital heart defects are diagnosed in approximately 1% of births in the United States. The prevalence of congenital heart disease has increased in the general population, with the steepest rise observed in adults with severe or complex lesions. An overall prevalence of 6 per 1000 adults has been documented. The median age of patients with severe lesions has increased from childhood to late adolescence.
How are congenital heart lesions often classified?
Congenital heart lesions can be classified as acyanotic or cyanotic. Cyanosis refers to a blue discoloration of the mucous membranes resulting from an increased amount of reduced hemoglobin. Central cyanosis occurs when the circulation is mixed because of a right-to-left shunt.
What is the proper workup for a patient with congenital heart disease?
A clinical assessment, 12-lead electrocardiogram (ECG), chest radiograph, and baseline oxygen saturation should be part of every initial assessment. Two-dimensional transthoracic echocardiography and Doppler and color flow imaging are used to establish the diagnosis and to monitor the evolution of documented hemodynamic complications.
What is the most common congenital cardiac anomaly in children?
A solitary VSD represents 15 to 20% of all congenital lesions and is the most common congenital cardiac lesion observed in children; its high spontaneous closure rates explain the lesser prevalence in adults.
What are genetic determinants of congenital heart disease?
About 20% of congenital heart defects are associated with a syndrome or chromosomal anomaly, and the most common such chromosomal anomaly is Down syndrome (trisomy 21), in which about 50% of patients have defects of the endocardial cushions and the ventricular septum. The most frequently observed defects in patients with Turner syndrome (45,X) are aortic coarctation, aortic stenosis, and atrial septal defect.
How does VSD sound on auscultation?
Auscultation reveals normal S1 and S2 without gallops. A grade 4 or louder, widely radiating, high-frequency, pansystolic murmur is heard maximally in the third or fourth intercostal space and reflects the high-pressure gradient between the left and right ventricles throughout systole. A thrill may be palpable at the left sternal border.
How is VSD diagnosed?
Echocardiography can identify the defect and determine the significance of the shunt by assessing left atrial and ventricular size, pulmonary artery pressure, and presence or absence of right ventricular hypertrophy.
What causes cyanosis in pulmonary hypertension?
Cyanosis occurs when persistent venous to arterial mixing results in hypoxemia. Adaptive mechanisms to increase oxygen delivery include an increase in oxygen content, a rightward shift in the oxyhemoglobin dissociation curve, a higher hematocrit, and an increase in cardiac output. When cyanosis is not relieved, chronic hypoxemia and erythrocytosis result in hematologic, neurologic, renal, and rheumatic complications.
What is Eisenmenger syndrome?
Eisenmenger complex refers to flow reversal across a ventricular septal defect (VSD) when pulmonary vascular resistance exceeds systemic levels. Eisenmenger physiology designates the physiologic response in a broader category of shunt lesions in which a right-to-left shunt occurs in response to an elevation in pulmonary vascular resistance. Eisenmenger syndrome is a term applied to common clinical features shared by patients with Eisenmenger physiology. The clinical manifestations of Eisenmenger's syndrome include dyspnea on exertion, syncope, chest pain, congestive heart failure, and symptoms related to erythrocytosis and hyperviscosity.1b On physical examination, central cyanosis and digital clubbing are hallmark findings. Systemic oxygen saturations typically vary between 75 and 85%. The pulse pressure narrows as the cardiac output falls.
What is ventricular septal defect (VSD)?
For anatomic classification of VSDs, the interventricular septum can be divided into four regions. Defects of the membranous septum are located in a small translucent area beneath the aortic valve and account for up to 80% of VSDs. Infundibular defects or supracristal outlet VSDs occur in the conal septum above the crista supraventricularis and below the pulmonary valve. Inlet defects are identified at the crux of the heart between the tricuspid and mitral valves and are usually associated with other anomalies of the atrioventricular canal. Defects of the trabecular or muscular septum can be multiple and occur distal to the septal attachment of the tricuspid valve and toward the apex.
What are hematologic complications of chronic hypoxemia?
Hematologic complications of chronic hypoxemia include erythrocytosis, iron deficiency, and bleeding diathesis. Hemoglobin and hematocrit levels as well as red blood cell indices should be checked regularly and correlated with systemic oxygen saturation levels. Symptoms of hyperviscosity include headaches, faintness, dizziness, fatigue, altered mentation, visual disturbances, paresthesias, tinnitus, and myalgia.
What is the treatment for Eisenmenger's syndrome?
In patients with Eisenmenger syndrome, bosentan (e.g., 62.5 mg twice daily for 4 weeks, then 125 mg twice daily) may improve hemodynamics and exercise capacity. In the iron-replete state, moderate to severe hyperviscosity symptoms typically occur when hematocrit levels exceed 65%. If no evidence of dehydration is present, removal of 500 mL of blood during a 30- to 45-minute period should be followed by quantitative volume replacement with normal saline or dextran. Treatment of spontaneous bleeding is dictated by its severity and the abnormal hemostatic parameters. For severe bleeding, platelet transfusions, fresh-frozen plasma, vitamin K, cryoprecipitate, and desmopressin have been used. Reduction in erythrocyte mass also improves hemostasis, so cyanotic patients undergoing surgery should have prophylactic phlebotomy if the hematocrit is greater than 65%.
What are clinical manifestations of ASD?
Initial symptoms include exercise intolerance, dyspnea on exertion, and fatigue caused most commonly by right-sided heart failure and pulmonary hypertension.2 Palpitations, syncope, and stroke can occur with the development of atrial arrhythmias.
What is a patent foramen ovale (PFO)?
Integrity of the fetal circulation depends on the patency of the foramen ovale. In most cases, the fall in pulmonary vascular resistance at birth induces the foramen to become sealed. Necropsy studies have revealed that the foramen ovale remains patent beyond the first year of life in about 30% of individuals, and clinical studies have demonstrated that the prevalence of patent foramen ovale is three times higher in patients with cryptogenic stroke.
How does VSD present clinically?
Minimal or mild defects usually cause no significant hemodynamic or physiologic abnormality. A moderate or severe defect causes left atrial and ventricular dilation consistent with the degree of left-to-right shunting.
What are neurologic complications of chronic hypoxemia?
Neurologic complications, including cerebral hemorrhage, can be caused by hemostatic defects and are most often seen after inappropriate use of anticoagulant therapy. Patients with right-to-left shunts may be at risk for paradoxical cerebral emboli. Focal brain injury may provide a nidus for brain abscess if bacteremia supervenes.
How does ASD sound on auscultation?
On auscultation, the hallmark of an ASD is the wide and fixed splitting of the second heart sound. Pulmonary valve closure, as reflected by P2, is delayed because of right ventricular overload and the increased capacitance of the pulmonary vascular bed. A soft midsystolic murmur generated by the increased flow across the pulmonary valve is usually heard in the second left interspace.
What are the variations in severity of VSD?
Patients who have a small defect with trivial or mild shunts are defined as those with a of less than 1.5 and normal pulmonary artery pressure and vascular resistance. Patients with moderate defects have a ratio of greater than 1.2 and elevated pulmonary artery pressure but not elevated pulmonary vascular resistance. Patients with a large and severe defect have an elevated ratio with high pulmonary pressure and elevated pulmonary vascular resistance.
What are pulmonary complications of chronic hypoxemia?
Pulmonary complications include massive pulmonary hemorrhage and in situ arterial thrombosis. A rapid clinical deterioration associated with progressive hypoxemia often marks the terminal stage of disease.
What is pulmonary hypertension?
Pulmonary hypertension secondary to structural disease of the heart or circulation can occur with or without an increase in pulmonary vascular resistance. Pulmonary vascular obstructive disease occurs when pulmonary vascular resistance rises and becomes fixed and irreversible. In the most common congenital anomalies, pulmonary hypertension is a result of increased pulmonary blood flow because of a native left-to-right shunt.
What are renal complications of chronic hypoxemia?
Renal dysfunction can be manifested as proteinuria, hyperuricemia, or renal failure. Focal interstitial fibrosis, tubular atrophy, and hyalinization of afferent and efferent arterioles can be seen on renal biopsy. Increased blood viscosity and arteriolar vasoconstriction can lead to renal hypoperfusion with progressive glomerulosclerosis.
What are sequelae of ASD?
Right-sided heart failure, atrial fibrillation, or atrial flutter can occur as a result of chronic right-sided volume overload and progressive ventricular and atrial dilation. Stroke can result from paradoxical emboli, atrial arrhythmias, or both. A rise in pulmonary pressure occurs because of the increased pulmonary blood flow.
What are clinical manifestations of Eisenmenger's syndrome?
The clinical manifestations of Eisenmenger's syndrome include dyspnea on exertion, syncope, chest pain, congestive heart failure, and symptoms related to erythrocytosis and hyperviscosity.1b On physical examination, central cyanosis and digital clubbing are hallmark findings. Systemic oxygen saturations typically vary between 75 and 85%. The pulse pressure narrows as the cardiac output falls.
What is the pathophysiology of VSD?
The pathophysiology and clinical course of VSDs depend on the size of the defect, the status of the pulmonary vascular bed, and the effects of shunt size on intracardiac hemodynamics. Unlike ASDs, a VSD may decrease in size with time. Approximately half of all native VSDs are small, and more than half of them close spontaneously; moderate or even large VSDs may also close in 10% or less of cases. The highest closure rates are observed in the first decade of life; spontaneous closure in adult life is unusual.
What is the pathophysiology of ASD?
The pathophysiology is determined by the effects of the shunt on the heart and pulmonary circulation. Right atrial and right ventricular dilation occurs as shunt size increases with pulmonary to systemic flow ratios greater than 1.5 : 1.
What is the consequence of Eisenmenger's syndrome?
The term Eisenmenger's syndrome should be reserved for patients in whom pulmonary vascular obstructive disease is present and pulmonary vascular resistance is fixed and irreversible. These findings, in combination with the absence of left-to-right shunting, render the patient inoperable.
How is PFO treated?
There is a probable small benefit of closure compared with medical therapy which is warfarin to an international normalized ratio of 2.0 to 3.0. Primary closure of a patent foramen ovale is clearly indicated when a patient has contraindications to medical therapy, if medical therapy has failed, or in the presence of a hypercoagulable state not treatable by medical therapy.
