Cardiovascular DisordersCardiovascular Disorders

Pathophysiology

Review of Anatomy & Physiology

• Anatomy– Chambers

– A-V valves

– Semilunar valves

– Coronary arteries

• Left– Ant. Descending

– Circumflex

• Right

• 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

– 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

– 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

• 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)

Cardiovascular PathologyCardiovascular 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

Risk factors for CVD

• Major ones

1. Hypertension

2. High cholesterol

3. Cigarettes

4. Diabetes

5. Family history

• Minor ones

1. Inactive lifestyle

2. Obesity

3. Gender

• 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

• 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

Heart DiseasesHeart DiseasesCoronary Heart Disease (CAD)

–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

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

• Chronic endothelial injury--gives you-- damaged endothelium– Causes:

1. Hypertension --- angiotensin II produces inflam. cytokines

locally

2. Smoking

3. Hyperlipidemia

4. Hypercholesterolemia

5. Hyperhomocystinemia

6. Hemodynamic factors

7. Toxins

8. Viruses

9. Immune reactions

• Disease of “generalized atherosclerosis” affects:

1. Heart

2. Brain

3. Peripheral arteries

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)

Congestive Heart Failure

– 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 (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

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 !!

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

Arrhythmias (Dysrhythmias)• Classification

– etiology is usually damage to the conducting system– types

• Too Fast1. 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 disassociation2. Bradycardia (less than 60)

• Sinus Arrhythmia» normal condition; rate changes with respiration

“sick sinus syndrome” = alternating bradycardia & tachycardia

– note that ventricular fibrillation = lethal arrhythmia

Congenital Heart Defects

• Most arise during the first 8 weeks of gestation

– 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

– 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

– 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

Valvular Disorders

– 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

Inflammatory & Infectious Heart Diseases

• Deals primarily with acquired illnesses that can cause:

• Endocarditis ---- valve

damage• Myocarditis ---- arrhythmias• Pericarditis --- effusion

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

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

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

Vascular disordersVascular disorders

• Hypertension – #1 cause of morbidity &

mortality of adult Americans

– Called “silent killer”

– 3 types:• Primary (essential)

• Secondary

• Malignant hypertension

• Effects of uncontrolled hypertension

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