Download Cardiovascular Disorders

Cardiovascular Disorders
Pathophysiology
Review of Anatomy & Physiology
• Anatomy
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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
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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 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
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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
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Major ones
1. Hypertension
2. High cholesterol
3. Cigarettes
4. Diabetes
5. Family history
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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 Diseases
Coronary 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
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Atherosclerosis leads to atheromas
– Atheromas = plaques of lipids, fibrin, cell debris with or without attached thrombi
– Key to their development = “endothelial injury”
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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
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Chronic endothelial injury--gives you-- damaged endothelium
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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
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Disease of “generalized
atherosclerosis” affects:
1. Heart
2. Brain
3. Peripheral arteries
Coronary Artery Disease (cont)
– diagnosis
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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
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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)
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Classification
– 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
Congenital Heart Defects
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Most arise during the first 8 weeks of gestation
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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
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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
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Deals primarily with acquired
illnesses that can cause:
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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 disorders
• Hypertension
– #1 cause of morbidity &
mortality of adult Americans
– Called “silent killer”
– 3 types:
• Primary (essential)
• Secondary
• Malignant hypertension
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Effects of uncontrolled hypertension
Vascular Conditions
– Emboli
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» 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