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Cardiovascular 1

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mlinnie's version from 2018-11-09 22:25

Section

Question Answer
Systolic heart failureInability of the heart to generate adequate cardiac output to perfuse tissues
Diastolic heart failurePulmonary congestion despite normal stroke volume and cardiac output
Left Heart FailureContractility- MI, Myocarditis, Cardiomyopathies. Leads to hypertrophy and dilation of the myocardium
Stroke volumecontractility, preload, and afterload
Right heart failureCommonly caused by a diffuse hypoxic pulmonary disease. Can result from an increase in left ventricular filling pressure that is reflected back into the pulmonary circulation
High-output failureInability of the heart to supply the body with blood-borne nutrients, despite adequate blood volume and normal or elevated myocardial contractility
. Trace a drop of blood flowing through the heart, pulmonary vasculature and systemic vasculature. Start systemic veinssystemic veins→ RA → RV → pulmonary arteries → lungs → pulmonary veins → LA → LV → aorta → systemic arteries → organs a tissues → systemic veins
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READ PHYSIO BOOK ABOUT HEART FOR ANATOMY REFRESHER

 

ECG components
Question Answer
P wave--atrial depolarization
PR interval--time from onset of atrial activation to ventricular activation
QRS complex--ventricular depolarization
T wave--ventricular repolarization
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Question Answer
Myocardial oxygen consumption (MVO2)correlates with total energy requirements, determined by 3 major factors--1. wall stress during systole (estimated by BP), 2. duration of systolic wall tension, and 3. contractile state of myocardium
Oxygen is delivered to heart by the coronary arteries. And only the coronary arteries, 70-75% O2 used immediately by cardiac muscle, Little to no oxygen reserve, So more energy needed you need to increase the coraonary blood flow
Factors directly affecting cardiac performancepreload, afterload, heart rate, contractility
Preloadpressure generated in left ventricle at the end of diastole, depends on end-diastolic volume
Afterloadresistance or impedance to ejection of blood from left ventricle, aortic systemic pressure is used as an index
Cardiac output =Stroke volume x heart rate
Stroke volume influenced bypreload, afterload, and contractility
Heart rate influenced byCNS, ANS, neural reflexes, atrial receptors, and hormones
Contractility influenced byend diastolic volume, sympathetic stimulation, myocardial oxygen supply
Afterload influenced byaortic pressure and aortic valvular function
Preload influenced byend- systolic volume and venous return
Heart ratecharacteristic of cardiac tissue, but subject to neural and hormonal influence
Contractilitycharacteristic of cardiac tissue, subject to neural and hormonal influence
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– Frank-Starling Law of the Heart ???????? Laplace’s Law

 

Question Answer
factors increasing contractility cause heart to operate at ahigher length-tension curve
heart failure is characterized by lower length-tension curve
stroke volume (SV; volume of blood ejected with each heart beat) depends on force of contraction
force of contraction depends onmyocardial contractility (or degree of myocardial fiber shortening)
force of contraction determined by1. changes in ventricular stretch caused by changes in ventricular volume (preload), and 2. sympathetic activation of ventricle
inotropic agents affectcontractility
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Inotropic agents
Question Answer
positive--increase velocity of contraction and SV; include TH, epinephrine, norepinephrine, dopamine and isoproterenol
negative--decreased velocity of contraction and SV; include alcohol, procainamide, quinidine and propanolol
Cardiac output (CO)quantity of blood pumped by left ventricle into the aorta each minute. CO = HR x SV. normally about 5 liters/min
Ejection fractionnot all of the blood is ejected from the ventricle, normal ejection fraction is about 60-75%
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Question Answer
Hypertensionconsistent elevation of systemic arterial BP, 50 million Americans have it (including children)
Primary hypertensions--most with hypertension have it as a primary disease
Secondary hypertension--caused by altered hemodynamics associated with diseases such as atherosclerosis
isolated systolic hypertension(diastolic pressure less than 90 mmHg) is manifestation of increased CO and/or rigid aorta
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Question Answer
Primary hypertensiongenetic and environmental factors may be responsible, genetic predisposition may be related to defects in renal sodium excretion, cell membrane. transport of sodium and calcium, and sympathetic response to neurogenic hormones. populations at risk have high sodium intakes. smoking is associated with a high incidence--nicotine is a vasoconstrictor and can increase systolic and diastolic pressure
Chronic hypertension,damages walls of systemic vessels, prolonged vasoconstriction with high pressure, thickens arteries and arteries to withstand stress, arterial smooth muscle hypertrophies and undergoes hyperplasia, injury stimulates inflammatory mediators, hypertension aggravates and contributes to atherosclerosis
Orthostatic hypotensiondecrease in systolic and diastolic pressure upon standing, normally, gravitational changes are compensated by reflex arteriolar constriction, increased HR and factors such as valve closure in the venous system and pumping action of leg muscles
Normally, with postural changes--volume shifts initiate baroreceptor reflex activity, which increases sympathetic activity, the reflex increases HR and constricts arterioles, BP maintained
Orthostatic hypotension accompanied by--dizziness, vision loss, syncope, Due to insufficient vasomotor compensation and reduction in blood flow to brain
Acute orthostatic hypotension associated with--prolonged immobility associated with illness, drug reactions (anti-hypertensive drugs and antidepressants), starvation, exhaustion, conditions associated with blood volume depletion, venous pooling, altered blood chemistry, elderly are particularly susceptible
Chronic orthostatic hypotensionmay be a primary problem, often secondary to adrenal insufficiency, DM, intracranial tumors and many other conditions
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BP Classification for Adults
Question Answer
Normal<120/<80
Prehypertension120-139/ 80-89
Stage 1 hypertension140-159/ 90-99
Stage 2 hypertension>160/ >100
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Question Answer
Heart FailureGeneral term used to describe several types of cardiac dysfunction that result in inadequate perfusion of tissues with blood-borne nutrients
Congestive heart failurecan be systolic or diastolic
Systolic heart failureInability of the heart to generate adequate cardiac output to perfuse tissues
Diastolic heart failurePulmonary congestion despite normal stroke volume and cardiac output
Myocarditisinflammation of the heart muscle. Viral, bacterial, fungal infections.
CardiomyopathiesDeterioration of the function of the myocardium
Left Heart FailureContractility- MI, Myocarditis, Cardiomyopathies. Leads to hypertrophy and dilation of the myocardium
Right heart failureCommonly caused by a diffuse hypoxic pulmonary disease, Can result from an increase in left ventricular filling pressure that is reflected back into the pulmonary circulation
High-output failureInability of the heart to supply the body with blood-borne nutrients, despite adequate blood volume and normal or elevated myocardial contractility
memorize