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Cardio Pathophysiology

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What are two types of cardiac cells
Electrical (pacemaker) and Mechanical (myocytes)
Spontaneous generation of action potentials in pacemaker cells is called
Automaticity
Action potential in pacemaker cells are associated with opening of what ion channel
Slow calcium
What are 4 cardiac cell characteristics
Conductivity, Contractility, Automaticity, Excitability
What is Absolute Refractory Period (ARP)
Cardiac cells can not conduct an electrical impulse (falls from beginning of QRS to midway of T wave)
What is Relative Refractory Period (RRP)
Cardiac cells have repolarized to threshold and can be depolarized in stimulus strong enough (falls from midway of T wave to end of T wave)
What is the basis of automaticity
Pacemaker cells are leaky to sodium at rest
How does NE and E from the SNS effect depolarization
They open the Na+/Ca++ channels leading to faster depolarization
How does acetylcholine from the PNS effect depolarization
Ach binds to muscarinic receptors which opens K+ channels slowing deplorization
The cardiac control center is located in what part of the brain
Medulla
Where are the baroreceptors located
Aorta and internal carotid arteries
What nerve conducts PNS activity
Vagus
What is the mechanism of most abnormal electrical impulse formation
Reentry
Name the 4 layers of a vessel from the inside out
Endothelium, Intima, Media, Aventitia
What extrinsic mechanism is involved in blood flow control
NE from the ANS causes vasoconstriction
What intrinsic mechanisms control blood flow
Autoregulation by brain, heart and kidney (monitor pressure and perfusion). Kidneys die at pressure greater than 80mmHg. Also have myogenic and metabolic hypothesis that adapt to pressure changes.
Vascular smooth muscle is very dependent on what extracellular mineral
Calcium
What situations may lead to thrombus development in the veins
Inactivity, IV catheter (if long term requirement-use subclavian)
Give an example of a heart condition that may lead to thrombus development
A-fib
Name some causes of blood vessel obstruction
Thrombus, emoblus, vasospasm, inflammation, mechanical compression
What causes the pain of a migraine headache
Dilation of cerebral vessels after a vasospasm leads to pounding headache
What is Monckeberg Sclerosis
Calcification in sclerotic area
What causes Arteriolar sclerosis
HTN - ususally seen in small vessels of eyes
List some modifiable risk factors for atherosclerosis
Smoking, HTN, glucose intolerance (dibetics have higher levels of fatty acids)
List some non-modifiable risk factors for atherosclerosis
Genetics, ethnicity and gender
What is the impact of thromboangitits obliterans
Inflammation that leads to decreased blood flow mainly seen in men
What triggers Raynold Syndrome
Cold or vibration or stress. Hands and fingers turn blue to white to red. Cause is unknown and mainly see in women
What is the difference between a true and false aneurysm
True-all three layers of vessel involved. False - one of the layers not effected (usually see in trauma or poor insertion of a tube)
What is the difference between a saccular and fusiform aneurysm
Saccular-weakness on one side of vessel. Fusiform-weakness on both side of vessel (Berry aneurysm)
What causes an aneurysm
Atherosclerosis and/or congenital weakness
What should you document in an acute arterial occlussion
Check and document upper and lower pulses and neurovascular (motor and sensory) function
What are some characteristics of acute arterial insufficiency
Pain, Pallor, Pulseless, Paralysis, Paresis, Poikilothermy
What are some signs of chronic arterial insufficiency
Intermittent claudication, atrophy of hair and skin, nails thicken
Name some causes of valvular incompetency
Obesity -vericose veins, Pregnancy (pressure on IVC plus progestins) cause leg swelling - should lay on left side also elevate legs
What veins are commonly affected in chronic venous incompetency
Deep veins (Femoral veins). Venous pressure over time equals arteriole pressure leading to stasis of blood. Skin turns black due to iron deposits
Describe the process leading to venous insufficiency
Ostruction of venous drainage leads to increased hydrostatic pressure causing edema and stasis
Describe the formation of PE
Venous stasis leads to thrombus formation, thrombus dislodges and occludes part of pulmonary circulation (hypoxic vasoconstriction, pulmonary edema and atelectasis) causing symtpoms (tachypnea, chest pain, dyspnea)
How are the lymphatics involved in blood volume control
They return 25-50% of blood proteins which maintain appropriate hydrostatic pressure. Without the proteins ascites and edema develop
What conditions promote lymphedema
Removal of lymph nodes (example radical mastectomy) arms swell up and alter blood flow breaking down the skin tissue in area
What is the difference between primary and secondary lymphedema
Primary is congenital (born without lymphatics or blocked thoracic duct). Secondary involves surgery
What are some risk factors for HTN
Age, Race, Sodium intake, Obesity
When should you think secondary causes of HTN
If person is under 20 or over 60
Name some potential causes of primary HTN
Excessive SNS, excessive RAS and insulin, too little naturietic peptide, insufficient dilators or excessive constrictors
List different forms of shock that can cause hypotension
Cardiogenic-pump failure, Anaphylactic-histamine dilation, Septic shock - endotoxins cause vasodilation, Distributive
What four factors determine cardiac oxygen consumption
Heart rate, contractility, afterload, wall tension
What causes stable angina and how is it treated
Increased workload due to stenotic vessel causes pain. Relieved by rest and NTG
What causes Prinzmetal (Variant) angina and how is it treated
Vasospasm of vessel unrelated to exertion or stress. Relieve via CCB and Long acting NTG
What happens in unstable angina
Plague rupture leads to partial occlussion of vessel. Clot dissolved before damage can occur
What happens in an MI
Plague rupture leads to complete occlussion of vessel causing myocardial cell death
Describe the pathogenesis of acute coronary syndrome
Plague ruptures exposing tissue thromboplastin which causes platelet aggregation and clotting cascade leading to thrombus development and eventually ischemia
What are typical EKG signs of ischemia
T wave peaking, flattening, inversion; ST segment elevation or depression; Large Q-waves
What is the difference between a transmurial infarct and a non-Qwave infarct
Transmurial - the entire thickness of the ventricular wall is effected. Non-Qwave - effects inner third to half on the ventricular wall
What factors effect cardiac output
HR, Preload, Afterload, Contractility
What nerves does the baroreceptors use to feedback to the CNS info. about HR
Cranial nerves IX and X
What 3 things are needed for proper contracility of the heart
Contracile proteins, ATP and free Ca++ ions in cytoplasm
How might afterload be increased
Aortic stenosis, systemic HTN
Describe the compensatory responses to decreased Cardiac Output
Immediate=increased SNS activity via baroreceptors, Followed by Renin system and Later by LV hypertrophy
Define heart failure
Inability to effectively pump the blood delivered to the heart
What is the difference in systolic dysfunction and diastolic dysfunction in HF
Systolic - (2/3 of people) - poor EF (<40%) often seen with MI. Diastolic (1/3 people) normal EF but poor relaxation often seen with old age
What causes left sided heart failure
Increased afterload (HTN, aortic stenosis); Impaired contractility (MI, ischemia, mitral regurg, aortic regurg);Obstruction of LV filling (mitral stenosis, tamponade); Impaired relaxation (LV hypertrophy, HOCM, Restrictive cardiomyopathy)
What are the backward and forward effects of left heart failure
Backward - Pulmonary congestion (dyspnea, orthopnea, cough, crackles, cyanosis) and Forward - poor cardiac output (fatigue, oliguria, confusion, restlessness, increased HR, faint pulses)
What are the causes of right heart failure
Left heart failure, lung disease, pulmonary HTN, PE, Pulmonic valve stenosis, RV infarct.
What are the backward and forward effects of right heart failure
Backward-Enlarged liver and spleen, ascites, anorexia, edema, JVD and Forward (fatigue, restlessness, oliguria, increased HR, confusion)
What happens during ventricular remodeling in an MI
LV thickens, wall stress increases aneurysm potential, healthy tissue becomes overworked and damaged
What happens during ventricular remodeling of CHF
Angiotensin II activates growth pathways to increase ventricular size to accommodate increased volumes--leads to further complications
What are the common valve disorders
Mitral stenosis, Mitral regurg., Aortic stenosis, Aortic regurg.
What are the signs and symptoms of mitral stenosis
Increased left atrium pressure and decrease LV filling leading to pulmonary congestion and low CO.
What arrhythmia is common with mitral stenosis
A-fib. May need to anticoagulate to prevent clot formation
What is the etiology of mitral stenosis
Rheumatic fever (type III hypersensitivity reaction), SLE, RA, Migrane med (Methysergide) - last three are rare
How do you treat mitral stenosis
Commissurotomy (break apart leaflets), Balloon valvotomy (breaks up calcium), Valve replacement
What is the Abx prophylaxis for mitral stenosis
Dental procedures: Amoxicillin. Nondental: Amp and Gent
What are symptoms of mitral regurgitation
Systolic murmur at apex and radiating to left axilla(Holosystolic in left decubitus position), prominent S3.
What is the difference in etiology between mitral regurg. and mitral prolapse
Mitral regurg. (abnormal leaflet or papillary muscle). MVP-leaflets balloon for unknown reason
What are the treatments for mitral regurg (MVP)
Asymptomatic MVP without regurg (EKG every 3-5 years), MVP with regurg (Abx prophylaxis for dental work), if have palpitations use BB
What are the signs and symptoms of aortic stenosis
Crescendo-decrescendo murmur radiating to neck, Prominent S4, Syncope-Dyspnea-Angina (classic triad), faint pulses, fatigue and pulmonary congestion as LV fails
What is the etiology of aortic stenosis
Calcium deposits on leaflets in older patients (if valve only has 2 leaflets calcium builds up more quickly), Younger patients usually see rheumatic fever as cause
What is the treatment for aortic stenosis
Surgery
What are the signs and symptoms of aortic regurg.
Diastolic murmur (thickened aortic root pulls leaflets apart), bounding pulse and wide pulse pressure (systolic minus diastolic), Austin Flint murmur (regurgent aorta flow plus mitral flow), palpitations, volume overload overstretches LV leading to failure and dyspnea,
What causes aortic regurg.
Abnormal leaflet or papillary muscle
What is the treatment for aortic regurg.
Left ventricle accomodates over the years to the extra volume until it can no longer stretch which requires valve replacement
What is the prognosis of acute aortic regurg.
Immediate surgery to avoid heart failure from the sudden overload on the LV which can't accommodate. Usually result of trauma
What are the different types of prosthetic valves
Mechanical-good longevity and need to anticoagulate (INR 2-3), Bioprosthetic (pig, human)-anticoag not needed, lower complication but higher failure rate
Describe some functions of the pericardium
Mesothelial cell secrete fluid (15-25cc), stabilizes, prevents overfilling, barrier to cancers from lungs (cancer results from secondary metastasis)
What are out patient causes of pericardial disease
Viral (Influenza, Coxsackievirus A & B, Varicella, AIDS, Epstein Bar) triggers inflammatory response leading to fluid accumulation
What are some in patient causes of pericardial disease
Trauma, Uremia (develop friction rub-need dialysis), MI (cell death triggers inflammatory response - Dressler syndrome post MI (autoimmune), Meds (Hydralazine, Procainamide), Other infections (C.difficile, diptheria, fungal), Rheumatoid, Radiation
Describe the pathogenesis of pericardial disease
Inflammation causes leakage of transudate then proteins start to leak out followed by white cells that give off an exudate
How many cc's of fluid is needed before pericardial effusion shows on X-ray
250cc (ECHO is best to evaluate)
What factors determine if a pericardial effusion is silent of symptomatic
Rate, Volume, Compliance
What are the effects of cardiac tamponade
Increased JVD, increased ventricle diastolic pressure, decreased CO and muffled heart sound
What is constrictive pericarditis
Recurrent pericarditis leads to fibrous, calcification of pericardial layers
Describe the infectious endocarditis process
A thrombus develops over injured endcardium leading to vegetations that attrack bacteria. The body tries to wall off the bacteria with fibrin which allows further proliferation of bacteria, eventually chips break off (seeding) and enter blood stream (fever)
What is the primary infectious agent (endocarditis) in non intraveneous drug users
Strep viridins, Staph aureus, Enterococci (usually aortic or bicuspid valve)
What is the primary infectious agent (endocarditis) in intravenous drug users
Staph. Aureus (tricuspid normally effected)
What bacteria cause infectious endocarditis from surgery to replace a valve
S. epidermidis, S. aureus, Gram negative organisms and fungi
What bacteria cause infectious endocarditis from transient bactermia
S. viridins, S. epidermidis, S. aureus
True of False. An athlete should stop exercising when they have a virus
True. Exercising can cause extra heart strain making it more susceptible to the virus damage
What is the mechanism of myocarditis
Virus (Coxsackie B) secretes toxins that change myocardium surface cells and the T-helper cell immune response attacks
List some etiologies of myocarditis
Viruses, Bacteria, Spirochetes (lyme disease-Borrelia burgdorferi), Antineoplastics(doxyrubison), Alcohol (cellular death), Peripartum (Twins or use of tocalytics to stop labor), CT disorders
What is cardiomyopathy
Structural abnormality of the myocardium causing HF symptoms
What are the three categories of cardiomyopathy
Dilated, Hypertrophic, Restrictive
What are the characteristics of dilated cardiomyopathy
Dilation of heart chambers that inhibits contractile forces and causes incompetent valve closure.
How would you treat dilated cardiomyopathy
ACEI, Positive inotropes (Frank-Starling mechanism eventually fails), BB
What causes dilated cardiomyopathy
Generally unknown but suspect viral and alcohol toxicity
What causes hypertrophic cardiomyopathy
Asymmetric hypertrophy of ventricular septum (muscle fibers are in disarray causing diastolic stiffness) that pushes into the LV causing poor ejection and poor coronary perfusion leading to arrythmias
What portion of the population is hypertophic cardiomyopathy most common
Athletes. Seems to be an autosomal dominance inheritence.
How would you treat hypertrophic cardiomyopathy
CCB not a positive inotrope
What causes restrictive cardiomyopathy
Endomyocardium Radiation or Metastatic tumor, Infiltration of myocardium by amyloid, sarcoid, scleroderma
What are the characteristics of restrictive cardiomyopathy
Abnormally rigid ventricles that impair diastolic filling but have normal systolic function

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