alterations of cardiovascular function muscle pump is ineffective ! tissue congestion, edema,...
TRANSCRIPT
1
Alterations of Cardiovascular Function
w Chapter 23
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Simplified Path of Blood Flow
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The Heart Layers
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Cardiac Conduction System
5
w Ventricles relaxed
w Blood entering atria
w Blood flows through AV valves into ventricles
w Semilunar valves are closed
Cardiac Cycle-Diastole
Cardiac Filling
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w Ventricles contract
w Blood pushes against AV valves and they shut
w Blood pushes through semilunar valves into aorta and pulmonary trunk
Cardiac Cycle-Systole
Cardiac Emptying
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Cardiac Cycle
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Arteriosclerosis
w Arteriosclerosis: normal consequence of aging w Hardening of the arteries, smooth muscle and
collagen grow into lumen and stiffen the wall w Atherosclerosis
w Type of arteriosclerosis w Fatty lesions in the intimal lining of large and
medium sized arteries
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w Lipids get into the vascular endothelium
w Proportional to LDL level
w White blood cells try to clear them away à foam cells
w WBCs and vascular endothelium release growth factors that promote plaque formation
w Plaques block the arteries
w *** inflammation plays a BIG role as an initiator
Atherosclerosis in a Nutshell
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1
3
1) Intimal injury allows LDL to penetrate vessel wall
2) LDL modifications trigger chemotaxis of monocytes
3) Monocytes enter vessel wall and phagocytize LDL
4) Engorged monocytes become ‘Foam’ cells & ‘Fatty Streak’ visible
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Atherosclerosis
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Complicated plaques are the ones that rupture and this exposes collagen which activates platelets and thrombi form
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Fatty Streak
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§ Chronic inflammatory process ensues causing smooth muscle proliferation and fibrous tissue accumulation
§ Now have fibrous plaque with isolated pools of lipid vulnerable to rupture
Atherosclerosis
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Atherosclerosis
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The most important complication of atherosclerosis
w Vessel Occlusion w Ischemia: may be reversible w Infarction: permanent damage
Clinical Consequences
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w Risk Factors for atherosclerosis and coronary artery disease w Smoking w Hypertension w Gender w Age w Hyperlipidemia w Sedentary w Stress w INFLAMMATION like in RA, obesity, periodontal
disease
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Sites of Atherosclerosis
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Peripheral Arterial Disease
w Atherosclerotic changes in the peripheral arteries result in tissue ischemia w Lower extremities are
most common w High risk group are men
in their 60’s & 70’s w More common with
atherosclerosis risk factors
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Peripheral Artery Disease
w Gradual onset of intermittent claudication (uncomfortable, or tired feeling in the legs that occurs during walking and is relieved by rest)
w Pain at rest only if severe PAD
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Peripheral Artery Disease
w Thromboangiitis obliterans (Buerger disease) w Occurs mainly in young men who smoke w Inflammatory disease of peripheral arteries
resulting in the formation of nonatherosclerotic lesions w Digital, tibial, plantar, ulnar, and palmar
arteries w Obliterates the small and medium-sized
arteries
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Atrophic Skin Changes
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Peripheral Arterial Disease
w Diagnostic Test Findings w Inspection w Check pulses w Ankle Brachial Index
w Treatment w Walking program w Avoid injury w Reduce risk factors w Antiplatelet agents w Surgery
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Peripheral Artery Disease
w Raynaud phenomenon and Raynaud disease w Episodic vasospasm in arteries and
arterioles of the fingers, less commonly the toes
w Raynaud disease is a primary vasospastic disorder of unknown origin
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Peripheral Artery Disease
w Raynaud phenomenon and Raynaud disease w Raynaud phenomenon is secondary to
other systemic diseases or conditions w Collagen vascular disease
(scleroderma), smoking, pulmonary hypertension, myxedema, and environmental factors (cold and prolonged exposure to vibrating machinery)
w Seen in patients with RA, SLE, Sjogren’s
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Raynaud’s Phenomenon
w Diagnosis w History w Example
w Treatment w Avoidance of cold w No Smoking w Medications (Ca++channel blockers dilate blood vessels
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Aneurysm
w Abnormal out pouching or localized dilation of a blood vessel or wall of the heart
w Various causes w Atherosclerotic plaque formation w Congenital abnormality of arterial wall w Trauma w Infection w "true" aneurysm is one that involves all three layers
of the wall of an artery w Classified also by shape
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Aneurysm
w Various locations (aorta most common) w Abdominal aorta (between renal arteries and iliac
branches) w Thoracic aorta (ascending, transverse or
descending) w Cerebral artery (at circle of Willis) w Femoral and popliteal arteries
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Aneurysm
w Complications w Rupture – risk increases with increasing size w Pressure on adjacent structures
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Berry Aneurysm
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w Berry & saccular used interchangeably. Are often congenital
w Fusiform, either partially or fully, by thrombus, plaque
w Dissecting: tears w associated with
hypertension
Aneurysms & Dissections
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Dissecting Aneurysm
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Abdominal Aortic Aneurysms
w Develop after age 50 w Usually men w Severe Atherosclerosis
& Hypertension are major causes
w Most (>90%) occur below the renal artery
w Pulsating abdominal mass may be first sign
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Hypertension
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Hypertension w Essential Hypertension
w 90% of hypertensive patients w Unknown cause w Men > Women w Black > White w Poor > Rich w Older > Younger w Obese > Thin
w Secondary Hypertension w 10% of hypertensive patients
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Hypertension
w Risk Factors w Constitutional Factors
w Family History, Race, Sex w Lifestyle Factors
w High sodium diet, obesity (increased vessel length increases resistance), Physical inactivity, Excessive alcohol consumption, Oral contraceptives, Sleep apnea
w Not stress (acute changes only) w Not high fat diets (risk of CAD) w Smoking increases risk of CAD but ? risk in HTN
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Hypertension
w Pathophysiologic Changes w Asymptomatic w Elevated blood pressure w Most are the result of chronic complications
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Hypertension
w Complications w Target Organ Damage
w Kidneys – Renal Failure w Brain – CVA, TIA w Heart – LVH, Angina, CAD, CHF w Eyes - Retinopathy w Blood Vessels - PVD
w Atherosclerosis w Cardiovascular disorders
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Hypertension
w Diagnosis w > 2 BP readings on > 2 separate days
w Treatment w Lifestyle Modification
w Reduce weight, Reduce sodium, Reduce alcohol, Increase exercise
w Pharmacologic Treatment w Stepwise approach
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Malignant hypertension: Rapidly progressive hypertension, diastolic pressure is usually >140 mm Hg with papilledema (optic disc swelling), biggest concern is encephalopathy Up to 1% of patients with essential hypertension develop malignant hypertension, but the reason some patients develop malignant hypertension whereas others do not is unknown.
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Orthostatic Hypotension
w Abnormal drop in blood pressure w Upon standing w Transient
w Symptoms w Dizziness and Syncope (fainting)
w Causes w Reduce blood volume, Drug induced, Aging,
Immobility
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Orthostatic Hypotension
w Diagnosis w Sitting and Standing BP measurements w Tilt table
w Treatment – alleviate the cause w Education w Adjusting medication w Support hose
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Disorders of Venous Circulation
w Varicose veins w Dilated and tortuous veins w Venous valves are incompetent
w Thrombophlebitis w Clot formation with inflammation w Deep vein is most dangerous
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Varicose Veins
w Dilated, tortuous veins, engorged with blood resulting from improper venous valve function w Weakening in valve allows backflow of blood w Increase pressure in the veins causing walls to
stretch w Primary
w Originates in the superficial veins w Secondary
w Impaired flow in the deep venous channels
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Varicose Veins
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Varicose Veins
w Pathophysiologic Changes w Dilated, tortuous, purple veins most pronounced in
the legs w Edema of the calves w Leg heaviness w Dull aching in the legs
w Complications w Blood clots secondary to venous stasis w Venous stasis ulcers
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Varicose Veins
w Testing w Visual inspection w Doppler ultrasonographic flow analysis
w Treatment w Treat underlying cause w Anti-embolism stockings w Regular exercise w Surgical stripping w Weight loss is patient is obese
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Diseases of the Veins
w Superior vena cava syndrome w Progressive occlusion of the superior vena
cava that leads to venous distention of upper extremities and head
w usually the result of the direct obstruction of the superior vena cava by malignancies
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Chronic Venous Insufficiency w Chronic venous insufficiency: inadequate venous
return over a long period w Consequence of valvular incompetence
w Venous muscle pump is ineffective w Tissue congestion, edema, impaired tissue
nutrition w Fat necrosis & skin atrophy w Brown pigmentation due to hemosiderin deposits w Stasis dermatitis and ulcers because poor O2
levels so cells die
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Chronic Venous Insufficiency
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Venous Thrombosis
w The acute development of a blood clot that may cause vessel occlusion or embolization w Thrombosis causes vessel irritation and resulting
inflammation which contributes to occlusion or embolization
w May occur in deep or superficial veins
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Venous Thrombosis Triad
w Venous Stasis w Bed rest, immobility, shock, airplane rides, long
car rides, w Hypercoagulability of Blood
w Pregnancy, childbirth, BCP’s, dehydration, cancer, SLE
w Vascular Trauma w Venous catheters, surgery, massive trauma, hip
fracture, orthopedic surgery
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Venous Thrombosis
w Pathophysiologic Changes w Tenderness, redness, and
warmth over the affected area due to inflammation
w Swelling of the affected leg from venous congestion
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Venous Thrombosis
w Prevention w Ambulation w Support hose w Low dose anticoagulation
w Treatment w Anticoagulation w Surgical clot removal
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Diseases of the Arteries and Veins
w Thrombus formation w Blood clot that remains attached to the
vessel wall w Thromboembolus: blood clot that dislodges
and travels to a new vessel w Arterial thromboembolus: source often the
heart & obstructs lower extremities, coronary and cerebral vessels
w Venous thromboembolus: source usually legs & obstructs pulmonary arteries
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Diseases of the Arteries and Veins
w Embolism w Bolus of matter that is circulation in the
bloodstream w Dislodged thrombus, air bubble, amniotic
fluid, aggregate of fat, bacteria, cancer cells, or a foreign substance
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Pericardium
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Pericarditis
w Inflammation of the pericardium as a result of systemic or cardiac diseases w Primary – usually viral or idiopathic w Secondary – infection, connective tissue disease or
trauma
w Often associated with fluid collection within the pericardial space
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Pericarditis
w Pathophysiologic Changes w Pericardial friction rub and sharp substernal pain w Shallow rapid respirations due to associated pleurisy w Mild fever resulting from inflammation w Dyspnea, orthopnea, tachycardia w Relief when sit up and slouch over
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fluid in pericardial cavity
restricts heart expansion
left ventricle cannot accept enough blood
decreased cardiac output
decreased blood pressure and
shock
right ventricle cannot accept enough blood
increased venous pressure; jugular
distension
Pericardial Effusion
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Pericarditis
w Testing w Echocardiogram shows pericardial fluid
w Treatment w Most cases resolve on their own
w Pericardiocentesis w Pericardial window w Pericardiectomy
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Cardiac Tamponade
w Rapid increase in intrapericardial pressure caused by fluid accumulation in the pericardial sac w Compression of the
heart chambers w Causes impaired
diastolic filling of the heart
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Cardiac Tamponade
w Causes w Acute MI w Connective tissue disorders w Adverse drug reactions w Infective pericarditis w Hemorrhage from trauma w Post irradiation pericarditis
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Cardiac Tamponade
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Coronary Artery Disease
w Impaired coronary blood flow w Narrowing of coronary arteries due to atherosclerosis
resulting in: w Heart disease secondary to myocardial ischemia w Strength of myocardial contraction is reduced w Wall motion is abnormal resulting in lower cardiac
output
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Coronary Artery Blood Flow.
w Coronary Arteries originate in the aortic sinuses w Controlled by aortic pressure (aortic resistance) w Perfuse during diastole
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w Imbalance in blood supply and the heart’s demands for oxygen w Less blood
w Atherosclerosis w Vasospasm w Thrombosis
w Higher oxygen demand w Stress w Exercise w Cold
Coronary Artery Disease
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Coronary Artery Disease
w Nontraditional risk factors w Markers of inflammation and thrombosis
w C-reactive protein, fibrinogen, protein C, and plasminogen activator inhibitor
w Hyperhomocysteinemia w Infection
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w Chronic Stable Angina w Pain when heart’s oxygen demand increases w coronary artery size is not changed
w Variant Angina w Pain when coronary arteries spasm w Prinzmetal’s angina (vasospastic angina,
occurs at rest), due to hyperactive sympathetic nerve, patient may have NO atherosclerosis or clots
w Intermittent coronary vasospasms w Silent myocardial ischemia
w Myocardial ischemia without pain
Coronary Artery Disease
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Angina
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w
Coronary Heart Disease
transmural subendocardial
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w ECG changes w T-wave inversion w ST-segment depression or elevation w Abnormal Q wave
w Serum cardiac markers w Proteins released from necrotic heart cells
w Myoglobin, creatine kinase, troponin I and T
Acute Coronary Syndromes
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Acute Coronary Syndromes
w Unstable Angina w Causes myocardial ischemia w Worse than stable angina but not quite a MI w Due to atherosclerotic plaque disruption
platelet aggregation hemostasis w Vasospasm may play a role
w Acute Myocardial Infarction w Ischemic death of myocardial tissue w Sudden onset Pain
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Myocardial Infarction
w Reduced blood flow through one or more coronary arteries causing myocardial ischemia and necrosis w Caused by coronary artery occlusion w If ischemia lasts more than 45 minutes irreversible
damage occurs w All infarcts have a central hypoxic area
w Transmural infarction involves the full thickness of the cardiac wall (myocardium)
w Subendocardial infarction involves the inner half of the cardiac wall (myocardium)
w Injured tissue is potentially viable if circulation is restored
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Acute Myocardial Infarction
w Ischemic death of myocardial tissue
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Acute Myocardial Infarction
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Myocardial Infarction
w Causes w Atherosclerosis w Thrombosis w Coronary artery stenosis or spasm w Platelet aggregation
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Myocardial Infarction
w Pathophysiologic Changes w Persistent, crushing substernal chest pain
w Caused by coronary artery occlusion w May radiate to left arm, jaw, neck or shoulder
w Cool extremities, hypotension due to impaired myocardial function
w Perspiration, anxiety, hypertension and feeling of impending doom resulting from pain or sympathetic stimulation
w Nausea & vomiting due to pain or vagal stimulation
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w Complications w Heart failure
w AMI is the most common cause of left HF w Cardiogenic shock w Pericarditis w Thromboembolism
w Rupture of the heart w Ventricular aneurysms w Cardiac Arrhythmias
w Most common cause of sudden death with AMI
Myocardial Infarction
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Ventricular Rupture of the Heart
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Myocardial Infarction w Structural and functional changes
w Myocardial stunning: reversible reduction of function of heart contraction after reperfusion not accounted for by tissue damage or reduced blood flow. Last for hours to days
w Hibernating myocardium: some segments of the myocardium exhibit abnormalities of contractile function. Until perfusion restored
w Myocardial remodeling: refers to the changes in size, shape, and function of the heart after injury to the ventricles. Often necrosis followed by fibrous scarring which is not a contractile tissue therefore function declines
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Myocardial Infarction
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Myocardial Infarction
w Treatment w Thrombolytic therapy within 3 hours of onset of
symptoms w Percutaneous transluminal coronary angioplasty to
open blocked or narrowed arteries w Oxygen w Bypass surgery
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Dysrhythmias
w Disturbance of the heart rhythm w Range from occasional “missed” or rapid beats
to severe disturbances that affect the pumping ability of the heart
w Can be caused by an abnormal rate of impulse generation or abnormal impulse conduction
w Respiratory sinus arrhythmia: is a naturally occurring variation in heart rate . inspiration triggers inhibitory signals to the vagus nerve so tonic attenuation of inherent SA node rate is transiently shut down thereby increasing heart rate
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w pulsus paradoxus (PP), also paradoxic pulse or paradoxical pulse, is defined as an exaggeration (more than 10 mmHg) of the normal variation during the inspiratory phase of respiration, in which the blood pressure declines as one inhales and increases as one exhales. It is a sign that is indicative of several conditions including cardiac tamponade, pericarditis, chronic sleep apnea, croup, and obstructive lung disease (e.g. asthma, COPD).[1]
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Dysrhythmias w Examples:
w Tachycardia: >100 bpm w Flutter: typical atrial flutter, has an atrial rate of 250
to 300bpm or atypical is typically faster, usually 340-350 bpm, ventricular flutter rate over 200bpm
w Fibrillation: >300 bpm irregular, and unsynchronized contraction of muscle fibers (atria or ventricles) Ventricular fibrillation is a cause of cardiac arrest and sudden cardiac death. The ventricular muscle quivers and is useless
w Bradycardia: under 60bpm, though it is seldom symptomatic until the rate drops below 50
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w Premature ventricular contractions PVC the heartbeat is initiated by the heart ventricles rather than by the SA node
w Junctional rhythm: AV node instead of SA node sets the heart rate
w Sick sinus syndrome, also called sinus node dysfunction, is a group of abnormal heart rhythms (arrhythmias) presumably caused by a malfunction of the sinus node, the heart's primary pacemaker. Bradycardia-tachycardia syndrome is a variant of sick sinus syndrome in which slow arrhythmias and fast arrhythmias alternate
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w Following the PVC there is a pause and then the normal beat returns - only to be followed by another PVC. The continuation of this pairing of beats is an example of bigeminy.
w PVCs that occur at intervals of 2 normal beats to 1 PVC is called trigeminy
w Quadrigeminy is where one PVC occurs after every 3 normal beats of the heart
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Heart condition in which delayed repolarization of the heart following a heartbeat, leading to re-entrant ventricular arrhythmias. Symptoms may only manifest to patient during extreme exercise, but that 1st symptom may be sudden death like in young athletes May be the result of various gene mutations Patient may be put on beta blockers or may get a defibrillator implant
Long QT Syndrome
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Heart block: impeded neuroconduction any place along the conduction pathway. AV blocks have 3 degrees with 3rd degree causing complete nerve block between the atria and ventricles
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Cardiomyopathy
w Group of disorders affecting the myocardium w Primary Confined to the myocardium w Secondary Other disease conditions
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Cardiomyopathy
w Hypertrophic cardiomyopathy w Autosomal dominant disorder or aortic stenosis or
anything increasing the workload of the heart over a chronic period
w Hypertrophied ventricle becomes stiff and noncompliant and unable to relax causing a reduction in ventricular filling
w 1 out of 500 in the general population w Common cause of sudden death in athletes w Signs and symptoms vary greatly
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Cardiomyopathy
w Dilated cardiomyopathy w Extensively damaged myocardium reduces
contractility causing a decline in systolic function and cardiac output (heart failure)
w Leading cause of heart transplant w Causes: viral, HTN, valve insufficiency
w Restrictive cardiomyopathy w Fibrosis and stiffening of the ventricle reducing the
ability to relax and fill during diastole resulting in a decrease in cardiac output, amyloidosis
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Cardiomyopathy
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Hypertrophic Cardiomyopathy
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Myocarditis
w Focal or diffuse inflammation of the cardiac muscle which may be acute or chronic w Inflammatory cardiomyopathy w Inflammation may lead to hypertrophy, fibrosis or
inflammatory changes of the conduction system w Usually resolves spontaneously w Heart muscle weakens and contractility is reduced
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Myocarditis
w Causes w Infection: bacterial, viral, etc. w Radiation therapy w Hypersensitivity immune reaction, autoimmune SLE w Toxins such as lead, chemicals and cocaine w Chronic alcoholism
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Myocarditis
w Complications w Arrhythmias and sudden death w Chronic valvulitis w Dilated cardiomyopathy w Heart failure w Pericarditis w Cardiac rupture w Thromboembolism
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Endocarditis
w Infection of the endocardium, heart valves or cardiac prosthesis w Causing deformities and destruction of valvular
tissue and chordae tendineae causing rupture and valvular insufficiency
w Collection of microorganisms, fibrin and platelets form vegetations that can cover the valve surface
w Vegetations may break off and form emboli w AKA: Bacterial Endocarditis
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Endocarditis
w Causes w Bacterial or fungal invasion w Predisposing factors
w Portal of entry w I.V. Drug abuse, surgery, teeth cleanings
w Damaged endocardial surface w Presence of a prosthetic heart valve w Rheumatic heart disease
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Endocarditis
w Signs & Symptoms w Fever and chills due to bacterial infection w Heart murmur due to turbulent blood flow
w Diagnostic Test Findings w Positive blood cultures w Elevated WBC count
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Endocarditis
w Complications w Acute renal failure w Brain abscess w Cardiac arrhythmia w Cerebral emboli w Heart failure w Meningitis w Death
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Rheumatic Heart Disease
w Acute rheumatic fever is a systemic inflammatory disease of childhood that develops after infections with group-A streptococcus (pharyngeal not skin) w Inflammation mainly involves the heart, joints, CNS,
skin and subcutaneous tissues. w Rheumatic heart disease is the cardiac and valvular
manifestations of rheumatic fever w Includes pericarditis, myocarditis & endocarditis
during the early phase w Chronic valve disease in the later phase
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Rheumatic Heart Disease
w Underlying Pathophysiology w GAS infection leads to a autoimmune reaction in
which antibodies produced to combat GAS affect connective tissues of the body
w Antibodies may attack healthy body cells by mistake because the bacterial antigens are similar to the body’s own cells
w Molecular mimicry
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Rheumatic Heart Disease
w Pathophysiologic Changes w Polyarthritis caused by inflammation w Firm movable subcutaneous nodules w Erythema marginatum skin rash found on the trunk w Carditis with dyspnea and chest pain w Sydenham’s chorea is a CNS manifestation
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Rheumatic Heart Disease
Erythema Marginatum
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Rheumatic Heart Disease
w Complications w Destruction of the mitral and aortic valves w Heart failure w Infection
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Rheumatic Heart Disease
w Treatment w Prompt treatment of GAS with antibiotics w Salicylates to relieve fever and pain w Corticosteroids for carditis w Corrective surgery
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Valve Stenosis
w Occurs when there is narrowing of a heart valve opening
w Stenosis of the heart valve w Blood accumulates in chamber preceding stenosed
valve w Results in increased chamber pressure due to
resistance to flow through the valve w May cause hypertrophy of cardiac wall
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Valve Insufficiency
w Occurs when heart valve leaflets don’t completely close
w Cardiac valve insufficiency w Incompetent heart valves allow blood to flow in both
directions through valve w Volume of pumped blood increases w Involved heart chambers dilate to accommodate
increased volume
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w The blood going through the valve makes a noise w These are called heart murmurs w You can identify them by:
w Where they are—which valve are they near? w How they sound—high or low pitched? w When they happen—systole or diastole?
Murmurs
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Mitral valve prolapse is the most common cardiac valve disease in the US. More common in women and is believed to be inherited, causes regurgitation of blood into the left atrium. Some experience fatigue, anxiety, and palpitations. Whether the MVP causes these symptoms is in dispute
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Heart Failure
w Syndrome that occurs when the heart cannot pump enough blood to meet the body’s needs (pump failure) w Results in intravascular and interstitial volume
overload and poor tissue perfusion w Classified as “left sided” or “right sided”
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Heart Failure
w Left Sided Heart Failure w Caused by scars from MI
w Pumping ability of the left ventricle fails w Cardiac output falls w Blood backs up into the left atrium… w Pulmonary edema
w Right Sided Heart Failure w Pumping ability of the right ventricle fails w Blood backs up into the right atrium and peripheral
circulation w Peripheral edema develops w Caused by left heart failure and COPD
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Heart Failure
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Pitting Edema
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Ascites
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Shock
w An acute failure of the circulatory system to supply the peripheral tissues and organs of the body with an adequate blood supply resulting in cellular hypoxia.
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w Cardiogenic
w Hypovolemic
w Obstructive
w Neurogenic AKA vasogenic
w Distributive
w Septic
Shock
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Cardiogenic Shock
w Diminished cardiac output severely impairs tissue perfusion (pump failure) w The left ventricle initiates a series of compensatory
mechanisms that attempt to increase cardiac output w The actions initially stabilize and later deteriorates as
oxygen demands increase on an already compromised heart
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Cardiogenic Shock
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Cardiogenic Shock
w Causes w Acute myocardial infarction w End stage cardiomyopathy w Cardiac tamponade w Myocardial ischemia w Ventricular arrhythmias
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Hypovolemic Shock
w Circulatory dysfunction and inadequate tissue perfusion caused by reduced intravascular blood volume
w Venous return is reduced and cardiac output fails w Acute loss of 15% to 20% of blood volume
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Hypovolemic Shock
w Causes w Blood loss w Burns w GI fluid loss
w Pathophysiologic Changes w Tachycardia restlessness w Reduced urine output w Hypotension w Cyanosis
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Hypovolemic Shock
w Diagnostic Test Findings w Hypotension w Many others…
w Treatment w Oxygen w Fluids w Blood replacement
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Obstructive Shock
w Mechanical obstruction of blood flow w Great veins w Heart w Lungs
w Causes w Aortic aneurysm w Pulmonary embolism (most common)
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Distributive Shock
w Inadequate tissue perfusion and circulatory collapse in response to infection (burns, anaphylaxis, neurogenic)
w Caused by loss of blood vessel tone and enlargement of the vascular compartment
w Capacity of the vascular compartment expands such that normal blood volume will not fill the circulatory system
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w Causes w Decreased sympathetic activity increased
parasympathetic activity: neurogenic w Brain or spine injury; anesthetics; insulin
shock; emotion w Vasodilator substances in blood
w Type I hypersensitivity (anaphylactic shock) w Inflammatory response to infection (sepsis
and burns)
Distributive Shock
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Distributive Shock
w Pathophysiologic Changes w Chills and fever due to proinflammatory cytokines w Tachycardia w Reduced urine output due to hypotension w Cyanosis
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Distributive Shock
w Complications w Death w Heart failure w Renal failure
w Diagnostic Test Findings w Blood cultures are positive w And ruled out anaphylaxis
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Distributive Shock
w Treatment w Antibiotics therapy w Medications to increase cardiac output w Oxygen
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Multiple Organ Dysfunction Syndrome
w Progressive dysfunction of two or more organ systems resulting from an uncontrolled inflammatory response to severe illness or injury such as burns or other traumatic injury, infection, acute pancreatitis
w Mortality rate ~50-90%
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Multiple Organ Dysfunction Syndrome
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Left-to-right shunts w Most common type of
congenital heart defect w Atrial septal defect –
incomplete closure of the embryonic atrial septum
w Ventricular septal defect – incomplete closure of the embryonic ventricular septum; usually associated with other congenital heart defects; large defects require surgery
w Patent (persistent) ductus arteriosus – failure of the ductus arteriosus to close at birth; may close with medication or may require minor surgical intervention
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Right-to-left shunts w Less common - result when there
is malrotation of the embryonic chambers
w Characterized by early cyanosis; require surgical intervention
w Tetralogy of Fallot – most common: 4 defects – w Ventricular septal defect w Pulmonary artery stenosis w Overriding aorta – misplaced
and sits low on the ventricular septal defect
w Right ventricular hypertrophy
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Right-to-left shunts w Transposition of great vessels –
2nd most common w Aorta arises from the right
ventricle and pulmonary artery from the left ventricle
w Incompatible with life w Requires immediate surgical
intervention