Pathophysiology CV


Question Answer Factors that increase O2 demand in the heart Tachycardia, hypertension, SNS stimulation, increased wall tension, increased end-diastolic volume, increased afterload, increased contractility Factors that reduce O2 delivery: Factors that decrease arterial oxygen content (CaO2) Hypoxemia, Anemia Factors that reduce O2 delivery: Factors that decrease O2 extraction Left shift of Hgb dissociation curve, decreased capillary density Factors that reduce O2 delivery: Factors that decrease coronary blood flow tachycardia, decreased aortic pressure, decreased vessel diameter, increased end diastolic pressure primary components of cardiac output preload, afterload, contractility, LV compliance, HR _____ determines the degree of tension cardiac fibers must develop before systolic ejection can occur afterload normovolemic anemia ____ (increases/decreases) cardiac output increases definition: the ventricular wall tension at the end of diastole preload independent of preload and afterload contractility decrease in contractility, decrease in ______ cardiac output what effects contractility (1) chemicles (particularly calcium) ***factors that increase contractility SNS stimulation, catecholamines, calcium, digitalis, phosphodiesterase inhibitors ***factors that decrease contractility myocardial ischemia, hypoxia, acidosis, hypercapnia, hyperkalemia, hypocalcemia, volatile anesthetics, propofol, beta-blockers, calcium channel blockers normal systemic vascular resistance 800-1500 dynes normal pulmonary vascular resistance 150-250 dynes the majority of afterload is usually set by ______ systemic vascular resistance ***greatest risk for perioperative MI unstable angina Risk factors for perioperative cardiac morbidity and mortality for non-cardiac surgery ***unstable angina, high risk sx, history of ischemic heart disease, hx of CHF, CVD, DM, serum creatinine > 2mg/dl definition of unstable angina new onset < 2months, increasing symptoms, duration > 30 min, not responsive to medical therapy ***Chart that illustrates the relationship between ventricular volume and ventricular output frank-starling curve ____ is lost with atrial fibrillation atrial kick (20-30% of EDV) These patients are more likely to experience a reduction in cardiac output with cardiac rhythm disturbances such as junctional rhythm patients with "stiff" or non-compliant ventricles ***What do pressure-volume loops tell us? systolic and diastolic function, integrity of the valves T/F – pressure-volume loops tell us a lot about heart rate and linear time false – nothing about these things normal stroke volume? Normal end systolic volume? 70ml, 50ml, pressure volume loop: length of the bottom represents what Stroke volume pressure volume loop: height of the sides represents what? pressure it takes to open/close valves pressure volume loop: a diagonal line going up at the bottom of the curve would represent what? non-compliant ventricle pressure volume loop: diastole represented by what phases? Systole represented by what phases? 4 and 1; 2 and 3 Ejection fraction (EF) equation SV/EDV -OR- (EDV-ESV)/EDV Normal EF 60-70% EF of left ventricular dysfunction EF < 40% two type of dysrythmias benign vs life-threatening heart rate is a function of autonomic tone, intrinsic firing rate of the dominant pacemaker ***Beats per minute: SA node, AV node, Perkinje fibers 70-80, 40-60, 15-40 T/F – all cells of the myocardium are capable of automaticity true the ____ nervous system modulates the heart rate autonomic PNS tone: The _____ (which nerve) innervates the SA node and the _____ (which nerve) innervates the AV node right vagus, left vagus SNS tone: what innervation accelerates the heart Cardiac accelerator fibers (T1-T4) what is the difference between the waveforms of an SA node action potential and a AV node action potential AV node potential has a lower slope during phase 4 Duration: PR interval 0.12 – 0.2 Duration: QRS interval 0.5 – 1.2 disease of the arteries that occurs due to deposition of fatty lesions on the intimal layer leading to thickening and hardening of the arteries Atherosclerosis leading cause of death of patients in their 40's and 50's CAD CAD: Fatigue in ____ (gender), shortness of breath ____ (gender) females, males

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