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

4. Pericarditis • An acute inflammatory process of the pericardium • Can be acute, chronic, or constrictive • May be due to autoimmune disease, infection, Rheumatic fever • Difficulty breathing, swelling of legs and ankles, dry cough, fatigue, anxiety, chest pain

5. Types of Pericardial Disorders (cont.) • Constrictive pericarditis • A disorder caused by inflammation of the pericardium • Eventual thickening, scarring and contracture of the pericardium occurs causing it to be less elastic. • This prevents the pericardium from stretching and results in reduced filling of the chambers of the heart. • This reduces the amount of blood pumped by the heart and causes blood to back up behind the heart, resulting in symptoms of heart failure. • Constrictive pericarditis may be life threatening if untreated.

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

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

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

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

12. Answer • Pericardial effusion • B. 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

13. 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

15. Classification of Coronary Heart Disease • Chronic ischemic heart disease • Chronic stable angina • Silent myocardial ischemia • Variant or vasospastic angina

16. Acute coronary syndromes (ACS) • Represent the spectrum of ischemic coronary disease • Ranges from unstable angina through myocardial infarction • Chest pain (angina) that feels like burning, pressure or tightness and lasts several minutes or longer • Pain elsewhere in the body, such as the left upper arm or jaw (referred pain • Nausea • Vomiting • Shortness of breath (dyspnea • Sudden, heavy sweating (diaphoresis)

17. 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

18. 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

19. Non-pharmacologic 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

20. Anti-platelet and Anticoagulant Therapy • Aspirin • The preferred anti-platelet agent for preventing platelet aggregation in persons with CHD • Inhibits synthesis of prostaglandin andthromboxaneA2

21. Anti-platelet 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

22. Determinants of ACS (Acute Coronary Syndrome) 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

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

24. Characteristics of Pain Associated With Unstable Angina • The pain has a more persistent and severecourse and is characterized by at least one of threefeatures: • 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.

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

26. 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

28. 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

29. Involvement of Heart Muscle in an Infarct • Transmural infarcts • Involves the full thickness of the ventricular wall • Occur when there is obstruction of a single artery • Associated with atherosclerosis involving major coronary artery

31. Subendocardial infarcts • Involves the inner one third to one half of the ventricular wall • Occur more frequently in the presence of severely narrowed but still patent arteries

32. Medical Management Following Infarct • Thrombolytic therapy • The use of drugs to break up or dissolve blood clots, which are the main cause of both heart attacks and stroke. • Revascularization interventions • Coronary artery bypass grafting (CABG) • Percutaneous coronary intervention (PCI) • Atherectomy • Cardiac rehabilitation programs

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

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

35. 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

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

37. 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

38. Primary and Secondary Cardiomyopathies • Primary • Genetic • Hypertrophic • The Heart Muscle thickens • Arrhythmogenic right ventricular • progressive fibrofatty replacement of the myocardium that predisposes to ventricular tachycardia and sudden death • Left ventricular non-compaction cardiomyopathy • the muscular wall of the main pumping chamber of the heart (the left ventricle) appears to be spongy

39. Secondary • Acquired cardiomyopathies • Myocarditis • Inflammation of the heart muscle • Symptoms • Abnormal Heart Beat • Flu-like Symptoms • Leg Swelling • Fainting • Stress cardiomyopathy • Caused by rapid and severe heart muscle weakness • Alcoholic cardiomyopathy

40. Mixed cardiomyopathy • Dilated cardiomyopathy • A condition in which the heart becomes weakened and enlarged, and it cannot pump blood efficiently • Due to alcohol, lupus, rheumatoid arthritis, coronary artery disease • Restrictive cardiomyopathy • A group of disorders in which the heart chambers are unable to properly fill with blood because of stiffness in the heart

41. 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.

42. 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.

44. 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 Haemophilussp. Actinobacillusactinomycetemcomitans Cardiobacteriumhominis Eikenellacorrodens Kingellakingae Gram-negative bacilli Fungi Infective Endocarditis

46. 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

47. 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

48. 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

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

50. 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 • Allows blood to enter the left atrium from the right atriumDuctusarteriosus • A shunt connecting the pulmonary artery to the aortic arch