Chapter 24 Disorders of Cardiac Function

1. Chapter 24Disorders of Cardiac Function

2. Definition and Functions of the Pericardium • Definition • A double-layered serous membrane surrounding the heart • Functions • Isolates the heart from other thoracic structures • Maintains its position in the thorax • Prevents it from overfilling • Contributes to coupling the distensibility between the two ventricles during diastole; they both fill equally

3. Types of Pericardial Disorders • Pericardial effusion • The accumulation of fluid in the pericardial cavity • Cardiac tamponade • Slow or rapid compression of the heart due to accumulation of fluid, pus, or blood in pericardial sac • Pericarditis • An acute inflammatory process of the pericardium • Can be acute, chronic, or constrictive

4. Types of Pericardial Disorders (cont.) • Constrictive pericarditis • Calcified scar tissue develops between the visceral and parietal layers of the serous pericardium • Cardiac output and cardiac reserve become fixed • Ascites, pedal edema, dyspnea on exertion, fatigue, and the Kussmaul sign

5. Clinical Manifestations • Acute pericarditis is based on clinical manifestations • ECG, chest radiography, and echocardiography • Friction rub • Chronic pericarditis • No pathogen identified • Autoimmune disorders

6. Coronary Circulation • Left main coronary artery • Left anterior descending artery • Circumflex branch • Right coronary artery • Posterior descending artery

7. Coronary Heart Disease • Impaired coronary blood flow that may cause: • Angina • Myocardial infarction or heart attack • Cardiac arrhythmias • Conduction defects • Heart failure • Sudden death

8. Question • Which of the following conditions will result in pathological changes arising from pulseless electrical activity? • Pericardial effusion • Cardiac tamponade • Pericarditis

9. Answer • Pericardial effusion • Cardiac tamponade: Cardiac tamponade is the result of restricted movement of the muscle and will inhibit ventricular contraction. The conduction is intact, but there will be little or no SV. • Pericarditis

10. The Evaluation of Coronary Blood Flow and Myocardial Perfusion • ECG • Changes in pattern or orientation of wave forms • Echocardiogram • M-mode, two-dimensional, Doppler, and esophageal • Exercise stress testing • Motorized treadmill and bicycle ergometer • Nuclear cardiovascular imaging methods • Myocardial perfusion imaging, infarct imaging, radionuclide angiocardiography, and positron emission tomography

11. Classification of Coronary Heart Disease • Chronic ischemic heart disease • Chronic stable angina, silent myocardial ischemia, and variant or vasospastic angina • Acute coronary syndromes • Represent the spectrum of ischemic coronary disease, ranging from unstable angina through myocardial infarction

12. Types of Angina • Chronic stable angina • Associated with a fixed coronary obstruction that produces a disparity between coronary blood flow and metabolic demands of the myocardium • Stable angina • The initial manifestation of ischemic heart disease in approximately half of people with CHD

13. Populations Affected by Silent Myocardial Ischemia • Persons who are asymptomatic without other evidence of CHD • Persons who have had a myocardial infarct and continue to have episodes of silent ischemia • Persons with angina who also have episodes of silent ischemia

14. Nonpharmacologic Treatment of Angina • Smoking cessation in persons who smoke • Stress reduction • Regular exercise program • Limiting dietary intake of cholesterol and saturated fats • Weight reduction if obesity is present • Avoidance of cold or other stresses that produce vasoconstriction

15. Antiplatelet and Anticoagulant Therapy • Aspirin • The preferred antiplatelet agent for preventing platelet aggregation in persons with CHD • Inhibits synthesis of prostaglandin, thromboxane A2 • Ticlopidine and clopidogrel • May be used when aspirin is contraindicated • Irreversibly inhibits the binding of ADP to its receptor on the platelets; no effect on prostaglandin synthesis

16. Antiplatelet and Anticoagulant Therapy (cont.) • Platelet receptor antagonists • Target a single step in the aggregation process • Block the receptor involved in the final common pathway for platelet adhesion, activation, and aggregation • Treat acute coronary syndrome

17. Determinants of ACS Status • Persons with an ACS are routinely classified as low risk or high risk for infarction based on • Presenting characteristics • ECG variables • Serum cardiac markers • Timing of presentation

18. Causes of Unstable Angina • Atherosclerotic plaque disruption • Platelet aggregation • Secondary hemostasis

19. Characteristics of Pain Associated With Unstable Angina • The pain has a more persistent and severe course and is characterized by at least one of three features: • It occurs at rest (or with minimal exertion) usually lasting more than 20 minutes (if not interrupted by nitroglycerin). • It is severe and described as frank pain and of new onset. • It occurs with a pattern that is more severe, prolonged, or frequent than previously experienced.

20. Basis for Diagnosis of Unstable Angina • Pain severity and presenting symptoms • Hemodynamic stability • ECG findings • Serum cardiac markers

21. Manifestations of ST-Segment Elevation Acute Myocardial Infarction • Abrupt onset • Severe and crushing pain, usually substernal, radiating to the left arm, neck, or jaw • Gastrointestinal complaints (nausea and vomiting) • Complaints of fatigue and weakness • Tachycardia, anxiety, restlessness, feelings of doom • Pale, cool, and moist skin

22. Factors Determining the Extent of an Infarct • Location and extent of occlusion • Amount of heart tissue supplied by the vessel • Duration of the occlusion • Metabolic needs of the affected tissue • Extent of collateral circulation • Heart rate, blood pressure, and cardiac rhythm

23. Involvement of Heart Muscle in an Infarct • Transmural infarcts • Involve the full thickness of the ventricular wall • Occur when there is obstruction of a single artery • Subendocardial infarcts • Involve the inner one third to one half of the ventricular wall • Occur more frequently in the presence of severely narrowed but still patent arteries

24. Medical Management Following Infarct • Thrombolytic therapy • Revascularization interventions • Coronary artery bypass grafting (CABG) • Percutaneous coronary intervention (PCI) • Atherectomy • Cardiac rehabilitation programs

25. Question • Which type of angina is brought about by exercise or stress? • Stable • Unstable

26. Answer • Stable: Stable angina does not present as a problem until there is an increase in workload. • Unstable

27. Myocardial Diseases • Myocarditis • Inflammation of the heart muscle and conduction system without evidence of myocardial infarction • Primary cardiomyopathies • Heart muscle diseases of unknown origin • Secondary cardiomyopathies • Conditions in which the cardiac abnormality results from another cardiovascular disease, such as myocardial infarction

28. Types of Cardiomyopathies • Dilated • Hypertrophic • Restrictive • Arrhythmogenic right ventricular • Peripartum

29. Cardiomyopathy Development (American Heart Association) • Heterogeneous group of diseases of the myocardium • Associated with mechanical and/or electrical dysfunction • Usually (but not invariably) exhibit inappropriate ventricular hypertrophy or dilatation • Due to a variety of causes that frequently are genetic • Cardiomyopathies either are confined to the heart or are part of generalized systemic disorders. • Often lead to cardiovascular death or progressive heart failure–related disability

30. Primary Genetic Hypertrophic Arrhythmogenic right ventricular Left ventricular noncompaction cardiomyopathy Inherited conduction system disorders Ion channelopathies Mixed cardiomyopathy Dilated cardiomyopathy Restrictive cardiomyopathy Secondary Acquired cardiomyopathies Myocarditis Peripartum cardiomyopathy Stress cardiomyopathy Alcoholic cardiomyopathy Primary and Secondary Cardiomyopathies

31. Treatment of Cardiomyopathy • Treatment depends on the type • Medication • Implanted pacemakers • Defribillators • Ventricular assist devices • Ablation • The goal of treatment is often symptom relief, and some patients may eventually require a heart transplant.

32. Predisposing Factors for Endocarditis • A damaged endocardial surface • A portal of entry by which the organism gains access to the circulatory system • The presence of valvular disease, prosthetic heart valves, or congenital heart defects provides an environment conducive to bacterial growth. • In persons with preexisting valvular or endocardial defects, simple gum massage or an innocuous oral lesion may afford the pathogenic bacteria access to the bloodstream.

33. Invasion of the heart valves and endocardium by a microbial agent Formation of bulky, friable vegetations and destruction of underlying cardiac tissues Systemic manifestations Streptocococci Enterococci Haemophilus sp. Actinobacillus actinomycetemcomitans Cardiobacterium hominis Eikenella corrodens Kingella kingae Gram-negative bacilli Fungi Infective Endocarditis

34. Manifestations of Rheumatic Fever • Acute stage • History of an initiating streptococcal infection • Involves mesenchymal connective tissue of the heart, blood vessels, joints, and subcutaneous tissues • Recurrent phase • Extension of the cardiac effects of the disease • Chronic phase • Permanent deformity of the heart valves

35. Function and Disorders of the Heart Valves • Function: promote directional flow of blood through the chambers of the heart • Dysfunction results in disorders: • Congenital defects • Trauma • Ischemic damage • Degenerative changes • Inflammation

36. Disruptions Occurring With Valvular Heart Disease • Narrowing of the valve opening so it does not open properly • Stenosis • Distortion of the valve so it does not close properly • Incompetent or regurgitant valve: permits backward flow to occur when the valve should be closed

37. Valve Disorders • Mitral valve disorders • Mitral valve stenosis • Mitral valve regurgitation • Mitral valve prolapse • Aortic valve disorders • Aortic valve stenosis • Aortic valve regurgitation

38. Fetal Blood Flow • Parallel rather than in series • Right ventricle delivering most of its output to the placenta for oxygen uptake • Left ventricle pumping blood to the heart, brain, and primarily upper body • Umbilical vein and two umbilical arteries • Foramen ovale • Ductus arteriosus

39. Cyanosis and Shunting • Defects that increase resistance to aortic outflow increase left-to-right shunting. • Defects that obstruct pulmonary outflow increase right-to-left shunting. • Crying, defecating, or stress of feeding may increase pulmonary vascular resistance and cause an increase in right-to-left shunting. • Resulting cyanosis

40. Factors Affecting Postnatal Pulmonary Vascular Development • Prematurity • Alveolar hypoxia • Lung disease • Congenital heart defects

41. Signs and Symptoms of Childhood Congenital Heart Disease • Symptoms associated with altered heart action • Heart failure • Pulmonary vascular disorders • Difficulty in supplying the peripheral tissues with oxygen and other nutrients

42. Kawasaki Disease • Skin, brain, eyes, joints, liver, lymph nodes, and heart • Vasculitis in the small vessels; progresses to involve some of the larger arteries • Immunologic in origin • Acute phase: fever, conjunctivitis, rash, involvement of the oral mucosa, redness and swelling of the hands and feet, and enlarged cervical lymph nodes • Subacute phase: defervescence and desquamation • Convalescent phase: complete resolution of symptoms until all signs of inflammation have disappeared after about 8 weeks

43. Types of Congenital Heart Defects • Patent ductus arteriosus • Atrial septal defects • Ventricular septal defects • Endocardial cushion defects • Pulmonary stenosis • Tetralogy of Fallot • Transposition of the great vessels • Coarctation of the aorta • Kawasaki disease

44. Question • Which of the following might result in the development of a cardiomyopathy? • Valvular stenosis • Valvular regurgitation • MI • Ischemia • All the above • None of the above

45. Answer • Valvular stenosis • Valvular regurgitation • MI • Ischemia • All the above: Any of these conditions can contribute to the development of a cardiomyopathy. • None of the above