Diseases of the heart fit into several general categories: congenital heart disease, ischemic heart disease, valvular diseases, and diseases of the myocardium (i.e., cardiomyopathies). Pericardial diseases and cardiac tumors are an additional small subset of conditions affecting the heart. A common manifestation of many different forms of heart disease is congestive heart failure (CHF). In general terms, congestive heart failure is the inability of the heart to pump enough blood to supply the body's oxygen requirements. It can represent failure of cellular adaptation (e.g., decompensated hypertrophy due to hypertension or chamber dilation due to regurgitant valves) or the outcome of myocardial damage caused by other diseases (e.g., scarring due to ischemic injury, inflammation, or accumulation of iron in hemochromatosis).
Classic symptoms of heart disease are chest pain or discomfort, dyspnea (including orthopnea and paroxysmal nocturnal dyspnea), palpitations, syncope, and edema. Dyspnea is an uncomfortable awareness of breathing. Orthopnea is dyspnea when in the recumbent position due to increased venous return and increased pulmonary venous pressure. Patients with orthopnea sleep upright on pillows to avoid becoming short of breath. Paroxysmal nocturnal dyspnea is when patients awaken with dyspnea 2–4 hours after falling asleep (due to central redistribution of peripheral edema).
An understanding of heart sounds is important in the clinical evaluation of heart disease. The S1 sound is caused by closing of the mitral and tricuspid valves, and the S2 sound is caused by closing of the aortic and pulmonary valves. In a patient with hypertension (systemic or pulmonary), closing of the associated valve (aortic or pulmonic) is accentuated (louder); in a patient with stenosis, the closing is diminished in strength (softer sound). S2 is physiologically split during inspiration (aortic, A2, first and pulmonic, P2 second)—increased venous return to the right side of the heart delays closure of the pulmonic valve and decreased return to the left side speeds closure of the aortic valve. Wide splitting of S2 is caused by a greater than normal delay in pulmonic closure (e.g., right bundle branch block, pulmonic stenosis) or earlier aortic valve closure due to decreased left ventricular volume (e.g., mitral regurgitation, ventricular septal defect). Paradoxical splitting (P2 first and A2 second) occurs with delayed closure of the aortic valve (e.g., left bundle branch block, aortic stenosis). A pathologic S3 occurs with ventricular systolic dysfunction during the rapid filling phase of diastole or from impact of the left ventricle against the chest wall. It is particularly common in the setting of CHF. S4 is from ejection of blood from the atrium into a noncompliant ventricle, as might be encountered in the setting of ventricular hypertrophy related to systemic hypertension, or in the setting of an acute myocardial infarct.
This chapter will discuss congenital heart disease, ischemic heart disease, hypertensive cardiovascular disease, congestive heart failure, valvular heart disease, cardiomyopathies, myocarditis, pericardial disease, and cardiac tumors.
Overview: There are three main categories of congenital heart disease: conditions causing a right-to-left shunt; conditions causing a left-to-right shunt; and conditions causing obstruction. In a right-to-left shunt, deoxygenated blood from the right side of the heart goes to the left side; thus, deoxygenated blood is delivered to the body. This type of shunt usually results in cyanosis at the time of birth. A left-to-right shunt increases the amount of blood delivered to the right side of the heart and will result in hypertrophy and dilation of the right atrium or right ventricle (or both), depending upon the type of shunt. Eventually, the pressure in the right side of the heart increases and surpasses that in the left side of the heart, resulting in a reversal of the shunt from left-to-right to a right-to-left shunt. This change is called Eisenmenger syndrome. With obstruction, an abnormally formed valve or vessel leads to pressure overload of the involved atrium or ventricle.
Causes of right-to-left shunt
- Morphology of tetralogy of Fallot
- Pulmonary stenosis.
- Right ventricular hypertrophy (as a result of the pulmonary stenosis).
- A ventricular septal defect shunts blood to the left side of the heart.
- The aorta overrides the ventricular septal defect.
- Important points: Tetralogy of Fallot is the most common cause of a right-to-left shunt in newborns.
- Complications of tetralogy of Fallot: Erythrocytosis, paradoxical emboli (through ventricular septal defect), endocarditis, and ventricular arrhythmias.
- Clinical presentation of tetralogy of Fallot: Cyanosis and failure to thrive; patients squat to alleviate symptoms by increasing venous return. The classic pattern seen on chest radiograph is the boot-shaped heart. Patients often have paroxysms of cyanosis (“tet fits”) associated with states of increased cardiac output that increase right-to-left shunting such as crying, exercise, and hot baths.
Tricuspid atresia: The gross morphology of tricuspid atresia is an atretic tricuspid valve that obstructs the flow of blood from the right atrium to the right ventricle. A ventricular septal defect or atrial septal defect is usually present. Approximately 75% of infants with tricuspid atresia are cyanotic within the first week of life.
Truncus arteriosus: The gross morphology of truncus arteriosus is caused by abnormal development of the ventricular outflow tracts, resulting in the presence of a common arterial conduit that receives a mixture of blood from the left and right ventricles. These patients present with symptoms initially due to left-to-right shunting, and they become cyanotic within 3 to 4 months because of progressive pulmonary vascular resistance.
Totally anomalous pulmonary venous return: The gross morphology is that the pulmonary veins do not return to the left atrium as normal, but rather drain abnormally into a left innominate vein or coronary sinus. Pulmonary venous blood ultimately reaches the left atrium through an atrial septal defect or patent foramen ovale.
Transposition of the great vessels: The gross morphology is that the aorta arises from the right ...
Log In to View More
If you don't have a subscription, please view our individual subscription options
below to find out how you can gain access to this content.
Want access to your institution's subscription?
Sign in to your MyAccess Account while you are actively authenticated on this website
via your institution (you will be able to tell by looking in the top right corner
of any page – if you see your institution’s name, you are authenticated). You will
then be able to access your institute’s content/subscription for 90 days from any
location, after which you must repeat this process for continued access.
If your institution subscribes to this resource, and you don't have a MyAccess account,
please contact your library's reference desk for information on how to gain access
to this resource from off-campus.
AccessMedicine Full Site: One-Year Subscription
Connect to the full suite of AccessMedicine content and resources including more than 250 examination and procedural videos, patient safety modules, an extensive drug database, Q&A, Case Files, and more.
Pay Per View: Timed Access to all of AccessMedicine
48 Hour Subscription
Pop-up div Successfully Displayed
This div only appears when the trigger link is hovered over.
Otherwise it is hidden from view.