Cardiac Pathophysiology

1. Cardiac Pathophysiology

2. Pericarditis • Often local manifestation of another disease • May present as: • Acute pericarditis • Pericardial effusion • Constrictive pericarditis

3. Acute Pericarditis • Acute inflammation of the pericardium • Cause often unknown, but commonly caused by infection, uremia, neoplasm, myocardial infarction, surgery or trauma. • Membranes become inflamed and roughened, and exudate may develop

4. Symptoms: • Sudden onset of severe chest pain that becomes worse with respiratory movements and with lying down. • Generally felt in the anterior chest, but pain may radiate to the back. • May be confused initially with acute myocardial infarction • Also report dysphagia, restlessness, irritability, anxiety, weakness and malaise

5. Signs • Often present with low grade fever and sinus tachycardia • Friction rub (sandpaper sound) may be heard at cardiac apex and left sternal border and is diagnostic for pericarditis (but may be intermittent) • ECG changes reflect inflammatory process through PR segment depression and ST segment elevation.

7. Treatment • Treat symptoms • Look for underlying cause • If pericardial effusion develops, aspirate excess fluid • Acute pericarditis is usually self-limiting, but can progress to chronic constrictive pericarditis

8. Pericardial effusion Accumulation of fluid in the pericardial cavity May be transudate May be exudate May be blood Not clinically significant other than to indicate underlying disorder, unless: Pressure becomes sufficient to cause cardiac compression – cardiac tamponade

9. Outcome depends on how fast fluid accumulates. • If development is slow, pericardium can stretch • If develops quickly, even 50 -100 ml of fluid can cause problems • When pressure in pericardium = diastolic pressure, get ↓ filling of right atrium, ↓ filling of ventricles, ↓ cardiac output → circulatory collapse.

10. Clinical manifestations • Pulsus paradoxus – B.P. higher during expiration than inspiration by 10 mm Hg • Distant or muffled heart sounds • Dyspnea on exertion • Dull chest pain • Observable by x-ray or ultrasound

11. Treatment • Pericardiocentesis • Treat pain • Surgery if cause is aneurysm or trauma

12. Constrictive (chronic) pericarditis • Years ago, synonymous with T.B. • Today, usually idiopathic, or associated with radiation exposures, rheumatoid arthritis, uremia, or coronary bypass graft

13. Pathophysiology: • Fibrous scarring with occasional calcification of pericardium • Causes parietal and visceral layers to adhere • Pericardium becomes rigid, compressing the heart →↓ C.O. • Stenosis of veins entering atria • Always develops gradually

14. Symptoms and Signs • Exercise intolerance • Dsypnea on exertion • Fatigue • Anorexia

15. Clinical manifestations • Weight loss • Edema and ascites • Distention of jugular vein (Kussmaul sign) • Enlargement of the liver and/or spleen • ECG shows inverted T wave and atrial fibrillation • Can be seen on imaging

16. Treatment • Drugs and diet • Digitalis • Diuretics • Sodium restriction • Surgery to remove restrictive pericardium

17. Cardiomyopathies • Disorders of the heart muscle • Most cases idiopathic • Many due to ischemic heart disease and hypertension. • Three categories: • Dilated ( formerly, congestive) • Hypertrophic • Restrictive • Heart loses effectiveness as a pump

18. Dilated cardiomyopathy ↓ C.O.; ↑ thrombi formation ; ↓ contractility, and mitral valve incompetence, arrhythmias Tx: relieve symptoms of heart failure, decrease workload, and anticoagulants; transplants

19. Hypertrophic Cardiomyopathy C.O. is normal,↑ inflow resistance, and mitral valve incompetence, arrhythmais and sudden death.

20. Restrictive cardiomyopathy Reduced diastolic compliance of the ventricle. C.O. is normal or↓;↑ formation of thrombi, dilation of left atrium, and mitral valve incompetence.

21. Disorders of the Endocardium:Valvular dysfunction • Endocardial disorders damage heart valves • Changes can lead to : • Valvular Stenosis = too narrow • Valvular Regurgitation = too leaky (or insufficiency or incompetence)

23. Valves that are most often affected are the mitral and aortic valves, but in I.V. drug users and in athletes that inject performance enhancing drugs, > 50 % involve only the tricuspid valve. • Heart Murmur – sound caused by turbulent blood flow through damaged valves.

24. Both types of valve disorders: • Cause increased cardiac work, and increased volumes and pressures in the chambers. • This leads to chamber dilation and hypertrophy. • Chamber dilation and myocardial hypertrophy are compensatory mechanisms to increase the pumping capability of the heart. • Eventually, the heart fails from overwork

25. Aortic Stenosis • Three common causes: • Rheumatic heart disease -Streptococcus infection – damage by bacteria and auto-immune response • Congenital malformation • Degeneration resulting from calcification

26. Aortic Stenosis • Blood flow obstructed from LV into aorta during systole Causes increased work of LV → LV dilation & hypertrophy as compensation → prolonged contractions as compensation Finally heart overwhelmed • → increased pressures in LA, then lungs, then right heart

27. Clinical manifestations • Develops gradually • Decreased stroke volume • Reduced systolic blood pressure • Narrowed pulse pressure • Heart rate often slow and pulse faint • Crescendo-decrescendo heart murmur • Angina, dizziness, syncope, fatigue • Can lead to dysrhythmias, myocardial infarction, and left heart failure

28. Mitral Stenosis • Most common of all valve disorders • Usually the result of rheumatic fever or bacterial endocarditis • During healing the orifice narrows, the valves become fibrous and fused, and chordae tendineae become shortened • Get decreased flow from LA to LV during filling • Results in hypertrophy of LA

29. By causing LA to become pump: • Get increased pulmonary vascular pressures; pressures increase through LA into lung • →pulmonary congestion • →lung tissue changes to accommodate increased pressures • →increased pressure in pulmonary artery • →increased pressure in right heart • →right heart failure

30. Clinical Manifestations • Atrial enlargement can be seen on x-ray • Rumbling decrescendo diastolic murmur, and accentuated first heart sound • Dyspnea • Tachycardia and risk of atrial fibrillation • Other signs and symptoms are of pulmonary congestion and right heart failure

31. Aortic Regurgitation • Caused by acute or chronic lesion of rheumatic fever, bacterial endocarditits, syphilis, hypertension, connective tissue disorder (e.g.Marfan syndrome) or atherosclerosis

32. Reflux of blood from aorta to LV during ventricular relaxation. • Causes LV to pump more blood w/ each contraction • → LV hypertrophy • LV takes on “globular shape” • →increased pressures in LA, lung, right heart

33. Clinical manifestations • Widened pulse pressure • Prominent carotid pulsations and throbbing peripheral pulses • Palpitations • Fatigue • Dyspnea • Angina • High-pitched or blowing heart sound during diastole

34. Mitral Regurgitation • Causes: mitral valve prolapse, rheumatic heart disease, infective endocarditis, connective tissue disorders, and cardiomyopathy • Permits backflow of blood from the LV into the LA during ventricular systole • Loud pansystolic murmur that radiates into the back and axilla

35. Causes blood to flow simultaneously to aorta and back to LA. • Both LV and LA pump harder to move same blood twice • →LV hypertrophy and dilation as compensation • Compensation works awhile, then see ↓C.O. • → heart failure • Also →LA hypertrophy • → increased pressures through lungs → ↑ pressures in right heart →right heart failure • Can see edema, shock

36. Clinical Manifestations • Weakness and fatigue • Dyspnea • Palpitations

37. Mitral Valve Prolapse • Cusps of valve billow upward into the LA during ventricular systole • Mitral regurgitation can occur • Most common valve disorder in U.S. • Studies suggest an autosomal dominant inheritance pattern • Many cases completely asymptomatic • Regurgitant murmur or midsystolic click

38. Clinical manifestations • Palpitations • Tachycardia • Light-headedness, syncope, fatigue, weakness • Chest tightness, hyperventilation • Anxiety, depression, panic attacks • Atypical chest pain

39. Once considered to be a psychiatric malady • May have an autonomic dysfunction in which large quantities of catecholamines are produced. • May be a normal variant • Can see: • chorda rupture • ventricular failure • systemic emboli and sudden death • actually associated with minimal morbidity and mortality

40. Management • Echocardiography for diagnosis • Related to degree of regurgitation • Antibiotics before invasive procedures •  blockers to relieve syncope, severe chest pain, or palpitations • Avoid hypovolemia • Surgical repair

41. General Treatment for Valve disorders • Antibiotics for Strep • Anti-inflammatories for autoimmune disorder • Analgesics for pain • Restrict physical activity • Valve replacement surgery

42. Heart failure • Definition – When heart as a pump is insufficient to meet the metabolic requirements of tissues. • Acute heart failure • 65% survival rate • Chronic heart failure • Most common cause is ischemic heart disease

43. Ischemic Heart Disease • Coronary Artery Disease (CAD), myocardial ischemia and myocardial infarction are progression of conditions that impair the pumping ability of the heart by depriving it of oxygen and nutrients.

44. Coronary Artery Disease • Any vascular disorder that narrows or occludes the coronary arteries. • Most common cause is atherosclerosis

45. The arteries that supply the heart are the first branches off the aorta • Coronary artery disease decreases the blood flow to the cardiac muscle. • Persistent ischemia or complete occlusion leads to hypoxia. • Hypoxia can cause tissue death or infarction, which is a “heart attack,” which accounts for about one third of all deaths in U.S.

46. Risk Factors • Hyperlipidemia • Hypertension • Diabetes mellitus • Genetic predisposition • Cigarette smoking • Obesity • Sedentary life-style • Heavy alcohol consumption • Higher risk for males than premenopausal women

47. Myocardial Ischemia • Myocardial cell metabolic demands not met • Time frame of coronary blockage: • 10 seconds following coronary block • Decreased strength of contractions • Abnormal hemodynamics • See a shift in metabolism, so within minutes: • Anaerobic metabolism takes over • Get build-up of lactic acid, which is toxic within the cell • Electrolyte imbalances • Loss of contractibility

48. 20 minutes after blockage • Myocytes are still viable, so • If blood flow is restored, and increased aerobic metabolism, and cell repair, • →Increased contractility • About 30-45 minutes after blockage, if no relief • Cardiac infarct & cell death

49. Clinical Manifestations • May hear extra, rapid heart sounds • ECG changes: • T wave inversion • ST segment depression

50. Chest Pain • First symptom of those suffering myocardial ischemia. • Called angina pectoris (angina – “pain”) • Feeling of heaviness, pressure • Moderate to severe • In substernal area • Often mistaken for indigestion • May radiate to neck, jaw, left arm/ shoulder