Cardiovascular Disorders

1. Cardiovascular Disorders Pathophysiology

2. Review of Anatomy & Physiology • Anatomy • Chambers • A-V valves • Semilunar valves • Coronary arteries • Left • Ant. Descending • Circumflex • Right

3. Cardiac Cycle = one complete heartbeat • Systole = contraction of heart ; Diastole = relaxation of the heart • In systole: • first the two atria contract (atrial systole) • then the two ventricles contract (ventricular systole) • Atrial diastole begins when ventricles contracting

4. Stroke Volume = volume of blood ejected from one ventricle during a beat • Cardiac Output = amount of blood one ventricle can pump each minute • normal = 5 liters per minute (at rest) • Note: CO = SV x Heart Rate

5. Stimulation of cardiac cycle • myocardium has automaticity; it will contract rhythmically by itself, but quite slowly (30-40 beats per minute) • “Vagal escape” = can’t voluntarily stop the heart • minute by minute stimulation of heart is by Autonomic Nervous System • parasympathetic (Vagus nerve) ---------SLOWS the heart rate • sympathetic (adrenergic) ----------------INCREASES heart rate • these impulses when reach the heart are carried throughout the myocardium via the Cardiac Conduction System • SA node • AV node • Bundle of His • Left bundle branch • Right bundle branch • Purkinje’s fibers

6. Control of heart is via “cardiac control center” in medulla • It’s messages sent to heart via ANS • Sensors • Baroreceptors = in wall of aorta & internal carotid; responds to BP & volume • R-A-A system = responds to BP & volume changes • ADH = responds to osmotic pressure changes via osmoreceptors in hypothalamus • Electrocardiogram & the cardiac cycle • Contraction = depolarization ---- sodium entering cell • In cardiac muscle get “plateau” --- thus, get absolute refractory period • Due to calcium entering cell • Recovery = repolarization --- potassium leaves cell • P = atria depolarization • PR length = time from SA none to AV node • QRS = depolarization of ventricles • ST segment & T wave = repolarization • (see next slide)

8. Cardiovascular Pathology • Major intrinsic functions of the heart • Strength of the muscular contraction --- INOTROPIC function • Rate (rhythm) of contractions ------------ CHRONOTROPIC function • Main types of cardio-vascular disease • (1) Coronary artery disease (CAD) • Angina pectoris • Myocardial infarction • High cholesterol & triglyceride • (2)Congestive heart failure (CHF) • Hypertension • (3)Cardiac arrhythmias • (4) Vascular occlusion • Terms • Preload = venous return to the heart • Afterload = peripheral resistance • Pulse pressure = difference between systolic & diastolic pressures • Pulse deficit = difference in rate between apical & radial pulse

9. Risk factors for CVD • Major ones • Hypertension • High cholesterol • Cigarettes • Diabetes • Family history • Minor ones • Inactive lifestyle • Obesity • Gender

10. Diagnostic tests for C-V function • EKG = electrocardiogram • Holter monitor • Echocardiogram • Stress test • Stress test with thallium imaging • Cardiac catheterization • Angiography • Doppler studies of peripheral vessels • Blood test • Enzymes (isoenzymes) • CK = creatine kinase • LDH = lactate dehydrogenase • C-reactive protein • Homocystine • Troponin • Arterial blood gases

11. Therapeutic modalities • General measures • Lifestyle changes • Drug therapy • Cardiac glycosides ---- digitalis • Coronary vasodilators • Anti- arrhythmics • Beta blockers ----- slow the rate • Calcium channel blockers --- slow the rate • Antihypertensives • Diuretics • Lipid- lowering agents • Anticoagulants

12. Heart Diseases • def: decreased flow through the coronaries arteries caused by narrowing which can result in : • myocardial ischemia (angina pectoris) • myocardial necrosis (myocardial infarction) • etiology • arteriosclerosis • from fat deposits (atherosclerosis) Key: see next slide • from aging • from systemic diseases such as diabetes & hypertension • *long term hypertension causes endothelial damage • vasospasm • thrombus and/or embolus • symptoms • no chest pain until at least 75% occlusion • in angina, pain on exertion relieved by nitroglycerine • in angina, get permanent damage within 6 hours if pain not relieved • in MI, pain on exertion or rest , not relieved by rest or meds Coronary Heart Disease (CAD)

13. Atherosclerosis • Atherosclerosis leads to atheromas • Atheromas = plaques of lipids, fibrin, cell debris with or without attached thrombi • Key to their development = “endothelial injury” • Lipid transportation & distribution • Lipids circulate as free fatty acids or lipoproteins (most transported as lipoproteins) • Lipoproteins= lipid-protein complexes that contain large insoluble glycerides or cholesterol • 5 types • Chylomicrons = formed in intestinal cells;carry free FA’s & monoglycerides into blood vessels • VLDL, IDL, LDL, HDL = made in liver • Density is determined by amount of protein in the lipoprotein • VLDL = triglycerides to tissues • LDL = carry cholesterol to tissues • HDL = carry cholesterol in plasma back to liver where it’s recycled & used or excreted in the bile • Lipoprotein lipase in endothelial cells breaks down Cholemicrons & VLDL to release fatty acids into cells

14. Chronic endothelial injury--gives you-- damaged endothelium • Causes: • Hypertension --- angiotensin II produces inflam. cytokines locally • Smoking • Hyperlipidemia • Hypercholesterolemia • Hyperhomocystinemia • Hemodynamic factors • Toxins • Viruses • Immune reactions

18. Disease of “generalized atherosclerosis” affects: • Heart • Brain • Peripheral arteries

19. Coronary Artery Disease (cont) • diagnosis • EKG changes, • stress test (with or without thallium) • cardiac catheterization with angiography • elevated enzymes(see figure) • treatment • prevention ----- decrease risk factors • coronary vasodilators • surgery: angioplasty or bypass graft (CABG)

21. definition = inability of cardiac muscle to pump adequate blood to sustain life • left sided failure = gives patient pulmonary edema • right sided failure = gives peripheral back up • also called Cor Pulmonale • etiology = many • main causes • hypertension • coronary artery disease • valvular disease Congestive Heart Failure

22. Congestive Heart Failure (cont) • types • left sided failure -------------- gives one pulmonary edema • Main causes = CAD & hypertension • right sided failure ---------------also called Cor Pulmonale; gives one peripheral edema , ascites, & hepatomegaly • main cause of pure right sided failure = lung pathology, especially COPD (Chronic Obstructive Pulmonary Disease) • also results from Pulmonary Hypertension (Phen-fen) • combined right & left sided failure is the most common presentation

23. Congestive Heart Failure (cont) • Dx • get decreased breath sounds on physical exam • get edema ------ pulmonary edema and/or peripheral edema • echocardiogram gives detail about size of heart chambers • Right Sided Failure = Cor Pulmonale • peripheral back up of fluid gives: • * distended neck veins • * hepatospleenomegaly • * edematous extremities • etiol: Acute Failure = pulmonary emboli • Chronic Failure = COPD • polycythemia occurs --- thus increase blood viscosity & catch 22 !!

24. Congestive Heart Failure (cont) • Dx • Pulmonary Edema (From pure left sided failure) • true medical emergency • path = in lungs, the fluid shifts to the extravascular space • Sx include dyspnea, orthopnea, increase pulse & resp. rate, & bloody frothy sputum, • Key = pulmonary circulation is overloaded with excess volume of fluid • Dx = rales, ronchi, wheezing * arterial blood gases shows a decrease in O2 saturation • Note that with either kind you can get both right & left ventricular hypertrophy (see previous slide) • Treatment • inotropic drugs -----------------------------increases contraction strength • diuretics -------------------------------------reduces edema • vasodilators if hypertension present ----reduces peripheral resistance

25. etiology is usually damage to the conducting system • types • Too Fast • 1. Premature contractions = atrial & ventricular • 2. Tachycardia (X2) = atrial & ventricular • 3. Flutter (X3) = atrial & ventricular • 4. Fibrillation (X4) = atrial & ventricular • Too Slow • 1. Heart Block (called AV block) • * 3 degrees; in third degree get complete disassociation • 2. Bradycardia (less than 60) • Sinus Arrhythmia • normal condition; rate changes with respiration • “sick sinus syndrome” = alternating bradycardia & tachycardia • note that ventricular fibrillation = lethal arrhythmia Arrhythmias (Dysrhythmias) • Classification

27. Congenital heart disease is divided into 2 categories: acyanotic & cyanotic • Acyanotic Congenital Heart Disease • Diagnoses are suspected by the presence of murmurs • 2 types: (1) increase pulmonary blood flow & (2) obstructive lesions • These lesions usually increase pulmonary blood flow • Ventricular Septal Defect (VSD) • most common (1/3 of all congenital heart problems) • not too serious as in over 50% of the cases the defect spontaneously closes by age 18 • Most close within first year of life • Atrial Septal Defect (ASD) • Persistence of fossa ovale • Patent Ductus Arteriosus (PDA) • 80% close within 2 weeks of age Congenital Heart Defects • Most arise during the first 8 weeks of gestation

29. Acyanotic Congenital Heart Disease (cont) • These are obstructive lesions • If severe they produce acyanotic CHF • Coarctation of the Aorta • In time get left ventricular failure • Hypotension distal to coarctation • Coarctation usually juxtaductal (ductus arteriosus) • When ductus closes ; patient goes into CHF • Aortic stenosis • Pulmonary stenosis • Severe form = pulmonary atresia

30. Cyanotic Congenital Heart Disease • Tetralogy of Fallot • most common cyanotic congenital heart defect • includes: VSD, pulm stenosis, dextroposition of aorta, RVH • Transposition of the Great Arteries

31. 2 main types • insufficiency = failure of valves to close • stenosis = hardening of cusps • both types allow for blood regurgitation • All come from disorders of endocardium • 2 etiologies • Congenital • Acquired • * from rheumatic fever • * from infective endocarditis • Congenital malformations most commonly affect; • aortic & pulmonary valve (see previous slides) • mitral valve most commonly affected in rheumatic heart disease • Mitral Stenosis --- most commonly from rheumatic fever • Mitral Insufficiency Valvular Disorders

33. Inflammatory & Infectious Heart Diseases • Deals primarily with acquired illnesses that can cause: • Endocarditis ---- valve damage • Myocarditis ---- arrhythmias • Pericarditis --- effusion

34. Pericarditis • def = acute or chronic inflammation of pericardium • frequently get blood or exudate into pericardial sac • can be primary or secondary to infection elsewhere in body • etiol : • Trauma (heart surgery) • infection e.g. - rheumatic fever or viral infections • secondary to MI • Tumor • TB • Radiation therapy • Sx : get symptoms from constrictive pericarditis • chest pain that fluctuates with inspiration • SOB • friction rub • chills, fever, malaise • Pericardial effusion (with cardiac tamponade) • Tx • acute = resolves • chronic = may need surgery

35. Myocarditis • def = inflammation of heart muscle • etiol = • viruses are commonest pathogen • complication of certain diseases such as rheumatic fever, mumps, diphtheria, flu • toxic agents e.g. alcohol, cocaine • Sx & Px = onset abrupt & disease resolves usually quickly with no residual heart damage Endocarditis • Note that the heart valves arise from the endocardium, thus any disease that results in endocarditis will result in valvular disease • etiol • septicemia &/or bacteremia • from systemic infection (such as rheumatic fever), invasive procedures, IV drug use • from heart disease &/or previous damaged heart valves • from abnormal immunologic reaction • Key = get vegetative growths on valves which may break off and cause emboli

36. Rheumatic Fever • First get Strept infection (pharyngitis) & 1-5 weeks later get abnormal immune reaction to the toxin from the bacteria • Sx • polyarthritis • carditis( primarily endocarditis) ---- follows joint pain within 1 week • Subcutaneous nodules --- on extensor surfaces • Chorea -- from affect on basal ganglia • rash on trunk (erythema marginatum) --- non pruritic * never on face or hands

37. Vascular disorders • Hypertension • #1 cause of morbidity & mortality of adult Americans • Called “silent killer” • 3 types: • Primary (essential) • Secondary • Malignant hypertension • Effects of uncontrolled hypertension

38. Vascular Conditions • Emboli • def = clots of aggregated material that break free from their original site and travel to a different site & obstruct • causes = blood, fat, air, bacteria, amniotic fluid • Arteriosclerosis • Aneurysms • def = weakening of arteriole wall & get local dilitation • Sx = bruit on auscultation • Phlebitis • superficial & deep • get no edema distal to area • Thrombophlebitis • get edema distal to area • Varicose Veins • Buerger’s Disease(Thromboangiitis Obliterans) • def = inflammation of small peripheral arteries and veins of extremities with clot formation • Raynaud’s Disease ( or Raynaud’s Phenomenon) • def = vasospastic condition of fingers, hands, and feet precipitated by cold and/or stress • women affected more than men; between ages 15-40