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67 Cards in this Set
- Front
- Back
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Site of highest resistance in the cardiovascular system?
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Arterioles
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Poiseuille's equation for resistance
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R = 8*n*l / pi*r^4
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Blood flow equation (hint: analogous to Ohm's law)
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Q = change in pressure / resistance
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Reynolds number predicts whether blood flow will be laminar or turbulent. What two factors increase Reynolds number?
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Decrease in viscosity (anemia, decrease in hematocrit) or increasing blood velocity (narrowing of vessel)
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Capacitance describes the ___ of blood vessles
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distensibility
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What is unstressed volume?
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The blood volume within the venous system. Arterial blood volume is known as the stressed volume.
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What is the pressure in: aorta, arterioles, capillaries, and vena cava
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100, 50, 20, 4
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What is the most important determinant of pulse pressure?
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Stroke volume
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How do you calculate Mean Arterial Pressure
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Diastolic pressure plus 1/3 pulse pressure
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What gives the SA-node, AV-node, and His-Purkinje system its automaticity character?
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Funny (I Na) channels
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What causes the A2:P2 split of S2 heart sound?
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Inspiration decreases intrathoracic pressure. Increased VR. Increased Preload to RV. Prolonged RV ejection phase. There is also a small decrease in ejection phase of LV.
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How does the parasympathetic nervous system effect the heart?
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Acts on SA node, atria, and AV node via vagal innervation. The neurotransmitter is ACh that acts on muscarinic receptors. Negative chronotropic (decrease I f), ionotropic and dromotropic (decrease Ca current and increase K current) effects.
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What is the S3 heart sounds?
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Ventricular gallop in mid-diastole. Rapid ventricular filling. Normal in young and athletes.
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How does the sympathetic nervous system effect the heart?
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Norepinephrine acts on Beta 1 receptors. Positive chronotropic, ionotropic and dromotropic effects.
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What is the S4 heart sound? What is the clinical correlation.
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Atrial gallop in late diastole. Clinical correlation: myocardial infarction causes a stiff ventricle.
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How does digitalis work?
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Increases the force of contraction by inhibiting Na/K ATPase in the myocardial cell membrane. Intracellular Na increases which decreases the Ca/Na exchange. Intracellular Ca increases.
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What heart sound could a brief period of exercise cause?
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Increased VR leads to an S3 sound.
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What is the first heart sounds, S1? When is it increased?
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Closure of AV valves in early systole. Loudest at the apex. It is increased in tachycardia and mitral stenosis.
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Cardiac output. Give two equations.
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= SV * HR (5 L/min)
= MAP/TPR |
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What is the second heart sounds, S2?
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Closure of the semilunar valves in early diastole. Physiological A2:P2 split
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What is Fick's principle?
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CO is related to whole body oxygen consumption. O2 consumption / (O2a - O2v) = CO
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What happens to the stroke volume in: aortic regurgitation and aortic stenosis
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Regurgitation - increased SV (normally there is still a decrease in effective stroke volume)
Stenosis - decreased SV |
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Below what % of Ejection fraction indicates heart failure?
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50%
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What heart sound could a brief period of exercise cause?
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Increased VR leads to an S3 sound.
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Determinants of Stroke Volume?
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Preload, contractility, afterload
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What is the LaPlace equation?
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sigma = P * r / 2h
sigma is wall tension h = wall thickness r = intralumenal radius P = intralumenal pressure |
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Increased afterload causes __1__ hypertrophy. Fluid overload causes __2__ hypertrophy.
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1 - concentric (mycoardial thickening)
2 - eccentric (sarcomeres are added in series) |
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Stroke work equation.
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= aortic pressure x stroke volume. Fatty acids are the primary energy source for stroke work.
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How does aortic stenosis change the ventricle pressure-volume loops?
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Afterload (pressure required to open aortic valve) increases. Longer phase II (isovolumeic contraction). Shorter ejection phase III. Therefore, stroke volume decreases.
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Aortic regurgitation (insufficiency) ____ pulse pressure due to a ____ diastolic pressure.
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Increases, low.
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What clinical diseases are associated with arotic regurgiation?
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Ehlers-Danlos, Marfans, syphilitic aortitis
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What does Rheumatic fever do to the heart?
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Causes Mitral stenosis. Symptoms develop 20 years later.
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When would a mitral valve prolapse be heard?
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Mid-systolic click.
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Above what Reynolds number does turbulent flow occur?
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2500
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When is an aortic stenosis murmur heard? What does it sound like? Where?
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Ejection type of murmur with a crescendo-decrescendo. Heard at 2nd right intercostal space and radiates to carotids.
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When is an aortic regurgitation murmur heard? What does it sound like?
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Early in diastole. Decrease in intensity.
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When is an mitral regurgitation murmur heard?
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Diastole.
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When is an mitral stenosis murmur heard? What does it sound like?
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Snap and rumble in diastole.
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Coronary artery blood flow depends on what three things?
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Length of diastole. Diastolic pressure of aorta, vascular resistance of coronary arteries.
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What is demand-ischemia?
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Persons with severe anemia may have elevated cardiac enzymes due to an ischemic heart.
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What is angina pectoris? Stable vs unstable?
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Chest pain caused by myocardial hypoperfusion (ischemia). Stable is due to exertion. Unstable is due to unfixed plaque, a medical emergency, chest pain at rest.
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What are the clinical features of diastolic heart failure?
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Increase afterload - concentric hypertrophy (sacromeres added in parallel) - leads o diastolic heart failure. Lead to backwards symptoms: dyspnea, shortness of breath, paroxsysmal nocturnal dyspnea.
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Name some forward heart failure symptoms.
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Related to systolic congestive heart failure. Fatigue, malasie.
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What is hypertrophic cardiomyopathy?
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Myocardium hypertrophies without a physiological stimulus. Occurs asymmetrically. Results in LV outflow obstructions. Results in syncope or sudden death. Tx with negative ionotropics.
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What murmur increases in intensity with the Valsalva manuver?
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Hypertrophic cardiomyopathy murmurs. Decrease LV preload. LV has to contract more strongly.
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What is the most common cause of dilated cardiomyopathy unrelated to volume overload?
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Excessive alcohol. Eccentric hypertrophy (minimal increase in wall thickness).
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What two important physiological roles does the refractory period of an action potential have?
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Prevents tetany and places an upper limit on heart rate.
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Force of contraction of the myocardial cells is proportional to intracellular ___ levels. What drugs effect these levels.
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Calcium. Digatalis increases Ca levels. Calcium channel blockers decreased Ca levels.
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Why must calcium must be pumped back into sarcoplasmic reticulum?
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So the cardiac muscle relaxes. This requires ATP.
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What causes vasovagal syncope? Why do patients survive?
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PNS outflow to heart during emotional upset. Ventricular escape rhythm saves the pt.
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What ECG abnormality could you see with an acute MI?
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ST segment elevation
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What ECG abnormality could you see with a bundle branch block?
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Split R wave
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What ECG abnormality could you see with an heart block?
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PR interval > 200 msec
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What ECG abnormality could you see with an old MI?
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Pathological Q wave
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What ECG abnormality could you see with an LVH?
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Deviation of mean QRS
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What ECG abnormality could you see with heart ischemia?
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Inverted T wave
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Define heart failure.
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Inadequate CO to meet metabolic demand (forward)
or Adequate CO maintained only at elevated filling pressures (backward failure) |
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Systolic heart failure results in decreased stroke volume and cardiac output. What is the pathogenesis (2)?
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Impaired contractility: MI's, regurgitations, dilated cardiomyopathy
Pathological increase in afterload: HTN, aortic stenosis |
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Diastolic heart failure results in an increase in LA filling pressure and pulmonary edema. What is the pathogenesis (2)?
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Impaired relaxation: LVH, HCM, RCM, transient MI
Obstruction of LV filling: mitral stenosis, tamponade |
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Thyrotoxicosis, severe anemia, and large AV fistulas can cause what type of heart failure?
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High output
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What is the most common cause of death in Duchenne muscular dystrophy?
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This X-linked disorder is caused by a defect in the gene for dystrophin, a protein necessary for sarcolemma stability. Muscle necrosis occurs. Death is due to fibrosis of the myocardium which leads to heart failure, pulmonary congestion, and arrhythmias.
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What condition causes a pathological S3?
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Aortic regurgitation. Early-mid diastole.
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Describe the action of nitrates and nitrites on the molecular level.
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Nitrates activate guanylate cyclase and increase cyclic guanine nucleotides. This activates cGMP dependent kinases that dephosphorylates myosin light chains. Vessels dilate.
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Nitrates are used to treat the symptoms of ____.
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Angina. Through the improvement of hemodynamics.
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Why do nitrates have a large first-pass effect?
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High-capacity organic nitrate reductase in the liver inactivates the drug.
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How are the following drugs administered?
1 - Nitroglycerin 2 - Amyl nitrite |
1 - sublingually for rapid delivery and short duration
2- volatile liquid that is inhaled |
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What are the adverse effects of nitrates and nitrites?
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Orthostatic hypotension, reflex tachy, blushing, burning sensation. Methemoglobinemia and cyanosis.
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