Chapter 13: Cardiac Pathology

Cardiac Pathology on cardiac pathology serves as a comprehensive review for medical students preparing for board exams, focusing on the pathophysiology, clinical presentation, and morphological changes associated with heart disease. The text begins by establishing ischemic heart disease as the leading cause of death in the United States, typically resulting from coronary artery atherosclerosis, and differentiates between the clinical presentations of stable angina, Prinzmetal variant angina, and the high-risk unstable angina. It provides an in-depth analysis of myocardial infarction, tracing the timeline of coagulative necrosis, the utility of serum markers like Troponin I and CK-MB for diagnosis, and the critical complications such as arrhythmias, cardiac rupture, and ventricular aneurysms that can follow an ischemic event. Significant attention is given to congestive heart failure, contrasting the pulmonary symptoms of left-sided failure, such as dyspnea and orthopnea, with the systemic venous congestion seen in right-sided failure, which leads to hepatosplenomegaly and dependent edema. The summary explores valvular heart disease, including the age-related degeneration seen in calcific aortic stenosis and the autoimmune mechanisms of rheumatic heart disease, where cross-reactive antibodies to Group A streptococci cause chronic valve damage and characteristic Aschoff bodies. Infective endocarditis is categorized by organism virulence, distinguishing between acute cases caused by Staphylococcus aureus and subacute cases often linked to Viridans streptococci. A major section is dedicated to congenital heart defects, classifying them into cyanotic right-to-left shunts like the Tetralogy of Fallot and Transposition of the Great Vessels, and acyanotic left-to-right shunts such as Ventricular Septal Defects, Atrial Septal Defects, and Patent Ductus Arteriosus, while explaining the pathophysiology of Eisenmenger syndrome and Coarctation of the Aorta. The chapter concludes by defining the primary cardiomyopathies—dilated, hypertrophic, and restrictive—based on their etiology and functional impairment, alongside discussions on pericardial diseases, carcinoid heart disease, and primary cardiac tumors like myxomas and rhabdomyomas associated with tuberous sclerosis.