Heart Flashcards
The best examples of CHDs that are diagnosed after infancy and childhood are:
- Bicuspid aortic valve stenosis: It is found in 1% or 2% of the total population. Because of hemodynamic changes related to the valvular abnormality, bicuspid aortic valves tend to degenerate and calcify and are an important cause of calcific aortic stenosis in late adult life.
- Mitral valve prolapse (‘‘floppy mitral valve’’): This occurs in approximately 2% to 3% of all adults and is usually diagnosed in adolescence or early adulthood.
How are CHDs classified clinically?
Three groups of defects are recognized depending on whether there are defects in the septum between the two sides of the heart and whether shunting of blood occurs:
- Malformations with a left-to-right shunt (acyanotic)
- Atrial septal defect
- Ventricular septal defect
- Malformations with a right-to-left shunt (early cyanosis)
- Tetralogy of Fallot
- Malformations without shunts
- Coarctation of the aorta
List five CHDs that present with early cyanosis at the time of birth or soon thereafter.
thereafter. Five diseases, all beginning with T, present with early cyanosis:
- Tetralogy of Fallot (most common).
- Transposition of the great arteries (aorta arising from the right ventricle and pulmonary artery arising from the left ventricle).
- Truncus arteriosus communis (aorta and pulmonary artery are not separated from each other and form a single vessel overriding both ventricles).
- Tricuspid valve atresia (usually with atrial septal defect).
- Total anomalous return of the pulmonary veins (oxygenated blood returns to the right instead of the left atrium).
What are the features of ventricular septal defect?
- This is the most common CHD (30%).
- It most often involves the upper part (i.e., the membranous part) of the septum (80%). Muscular septal defects are less common but may be multiple.
- Small defects (50% of all) are recognized by high-pitched holosystolic murmur (Roger disease). They tend to close spontaneously in the first 2 years of life.
- The shunt is initially left to right, leading to pulmonary hypertension and right ventricular hypertrophy.
- Reversal of the shunt occurs when the pulmonary hypertension exceeds the pressure in the aorta.
- & Reversal of the shunt from left to right to right to left (Eisenmenger syndrome) leads to cyanosis (cyanose tardive)
What are the features of atrial septal defect (ASD)?
- ASD accounts for 10% of all CHDs.
- It may present in several forms depending on which part of the septum is involved.
- Ostium secundum defect occurs at the fossa ovalis and represents the most common form of ASD (90%).
- Ostium primum defect involves the lower portion of the septum and may be associated with deformities of the mitral valve.
- Sinus venosus–type defect is located at the entry level of the superior vena cava into the right atrium.
- Shunt is left to right and causes fewer problems than ventricular septal defect (VSD).
- Pulmonary hypertension and heart failure occur in 10% of cases.
- ASD is usually diagnosed in early adult life (probably the most common CHD to be diagnosed in adult life)
Explain the pathophysiology of tetralogy of Fallot.
The narrowing of the pulmonary artery does not allow the entry of venous blood into the lungs. Instead, the unoxygenated venous blood passes through the VSD into the aorta that is overriding the VSD and thus receives the blood from both ventricles. The entry of the venous blood into the aorta leads to cyanosis and generalized hypoxia. In addition to the complex cardiologic findings, other clinical features include:
- Cyanosis (Bluish discoloration of the skin and mucosa may be evident at birth. In some infants, cyanosis develops at variable rates after birth, but in most children it is evident by age 4 months.)
- Hypoxemic spells (These spells are marked by deepening cyanosis or dyspnea. The children may faint or lose consciousness.)
- Retarded growth
- Squatting position frequently assumed by older children
- Clubbing of fingers
Mild cases of tetralogy of Fallot
Acyanotic Variety
What is coarctation of the aorta?
Coarctation of the aorta is characterized by narrowing of the aorta. It occurs in two forms:
- Infantile form: In this condition, the aortic arch and the ascending aorta are markedly narrowed. Ductus arteriosus does not undergo atresia, and it serves as the conduit for the blood to the aorta below the narrowing. Most infants do not survive without surgical correction of the defect. The head and the upper extremities are hypoxic, whereas the lower parts of the body (receiving the venous blood through the open ductus arteriosus) are cyanotic.
- Adult type: The narrowing of the aortic arch occurs opposite the insertion of the ductus arteriosus, which undergoes normal atresia. Because of aortic narrowing, there is hypertension in the head and upper extremities (i.e., parts of the body supplied by the arteries originating from the arch of the aorta). The parts of the body below the obstruction are hypoxic, and the blood pressure measured on the legs is lower than the pressure measured on the arms. Collateral circulation develops through internal mammary arteries so that the arterial blood from the branches of the subclavian arteries may provide oxygen to the aorta beyond the obstruction. Collaterals that involve the intercostal arteries cause notching of the ribs.
What is patent ductus arteriosus?
Ductus arteriosus is a normal fetal blood vessel allowing the blood from the venous system to bypass the lungs. After birth, ductus undergoes atresia and transforms into a narrow strand of connective tissue. Delayed occlusion of the ductus is a common finding in prematurely born infants. Ductus is kept open by prostaglandin (PGE2), and closure can be accelerated by injecting inhibitors of PGE2, such as indomethacin.
If the ductus arteriosus does not close, it will provide a venue for the reflow of arterial blood from the aorta into the pulmonary artery. This left-to-right shunt is associated with a loud ‘‘machinery murmur.’’ Pulmonary hypertension develops.
How common are heart tumors?
Primary heart tumors are so rare that they are not included in official statistics, and their real incidence is not known. Metastases are much more common, but even these secondary tumors are rare.
Myxomas account for more than 50% of all primary heart tumors. Most myxomas are sporadic, but some occur as part of Carney syndrome (skin and endocrine tumors and schwannomas).
List the most important facts about myxomas.
- They are most often (80%) found in the left atrium.
- They typically arise from the atrial septum around the fossa ovalis.
- Most are pedunculated, but some are broad based and sessile. The size varies, but most are 5 mm to 5 cm.
- On gross examination, myxomas appear gelatinous (‘‘myxoid’’).
- Histologically they are composed of spindle-shaped cells surrounded by loose myxoid matrix.
What are the clinical features of cardiac myxomas?
- Tumor may have a ball-valve effect and partially obstruct the mitral valve. Mitral obstruction results in symptoms that are indistinguishable from those caused by mitral stenosis.
- Symptoms may be nonspecific (e.g., fever, anemia, and elevated erythrocyte sedimentation rate) and are often described as protean (varied).
- Tumor may fragment and give rise to arterial emboli.
- Echocardiography is the most useful technique for visualizing the tumors.
What are rhabdomyomas?
Rhabdomyomas are the most frequent primary benign tumor of the heart in infants and children.
They are actually hamartomas or malformations rather than true neoplasms.
Cardiac rhabdomyoma is associated with tuberous sclerosis due to defect in the TSCI or TSC2 tumor suppressor gene. The TSC proteins stimulate the cell growth and are involved in myocyte overgrowth.
Rhabdomyomas are generally small, gray-white myocardial masses protruding into the ventricular chambers. Histologically they are composed of large, rounded, or polygonal cells containing numerous glycogen-laden vacuoles separated by strands of cytoplasm running from the plasma membrane to the more or less centrally located nucleus, the so-called spider cells.
What are the most common malignant tumors of the heart?
Primary malignant tumors of the heart are extremely rare. Histologically, these tumors are sarcomas (angiosarcoma) or mesotheliomas. Metastases of malignant tumors originating in other organs are approximately 50 to 100 times more common than either primary benign or malignant cardiac tumors. Most often, these metastases originate in primary malignant tumors of the lung and breast. Malignant melanomas also tend to metastasize to the heart. Metastases may grow in any part of the heart, but most often they are found in the pericardium.
