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28 Cards in this Set
- Front
- Back
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1. Define Cardiac Index, and BSA and how to calculate them? |
Cardiac Index-Hemodynamic parameter that relates cardiac output from left ventricle in one minute to body surface area (BSA), relates heart performance to the size of the individual.CI=CO/BSA=SV x HR/BSABSA(m^2)=sqrt(height(m) x weight(kg))/36 |
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Typical values of flow and Pressures for LVAD, TAH (separate for Left and right ventricle) |
TAH - Max Flow Rate - (8 - 10 L/min)/(3 - 5 L/min)Max Pressure - (300 mmHg)LVAD - Flow Rate: Full (2.5 - 4 L/min) Flow RatePartial (.49 +/- .46) Flow Rate |
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Why TAH designs very often preserve native atria? |
TAH are often preserved because pump inlets are mounted / integrated with left and right atria. Heart valves and ventricle are replaced the left and right atria are kept. |
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What are the advantages of continuous flow LVADs over pulsatile flow designs? |
Continuous flow LVADs advantage doesn’t need to be synchronized to EKG. Continuous flow LVAD has centrifugal pump in it. |
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What is hemolysis? |
Hemolysis - Rupture or destruction of red blood cells. Shear rate (stress) too high -> Hemolysis |
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What are the indicators of hemolysis? |
A high shear stress rate (NIH, into vitro, in vivo) |
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When thrombus forms inside the LVAD, TAH chamber? |
Thrombus - Occur when shear rate (stress) too low (in-vivo) |
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What methods are used to measure velocities inside the TAH/LVAD prototype? |
Methods to measure velocities inside TAH / LVAD prototypeMoens - Kurtweg Equation / laser one momentry, particle visualition,valve flow |
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How do we define input impedance of the cardiovascular system? |
Input impedance is what the device is going to read from the heart.P = abs(P)expi(wt-gamma) |
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What animal models are used for TAH and LVAD studies? |
TAH: CalvesLVAD: Goats, sheepRats: Ventricle loading and unloading LVAD procedure |
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Definition of NIH
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Normalized Index of HemolysisNIH(g/100L)=[deltaHB*V*(100-Ht)]/[(Q*T)/100]Delta(Hb) - Increase in Free Hemoglobin Concentration [g/L]V - Total Blood Volume (L), Q is flow rate (L/min), Hl is hemotocri in%, T - duration of test(min)
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Definition of HRI
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Hemolysis Rate Index - HRI(g/hr) = [delta(Hb+v+(100-Ht)/T]
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Why partial support with LVAD needs to be synchronized with ECG? |
Partial support needs to be synchronized with EKG because synchronization assures LVAD ejects blood when aortic valve is closed. |
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What are the two typical ways of connecting LVAD to the circulatory system? |
Two ways to connect to LVAD to circulatory systemare non-pulsatile (continuous LVAD) and pulsatile. |
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What are the typical values for SVR and PVR? |
SVR - 4.6 - 29.8 wood units (mmHg / 1 min^-1)PVR - Pulmonary vascular resistance, 2.8 - 3.4 wood units (mmHg / min^-1) |
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What feature of the circulatory system is represented by the windkessel model? |
The feature of the circulatory system represented in windkessel model is from pressure relationship to big arteries (ex. aorta) |
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What are the advantages of the distributed model of the circulatory system over the windkessel model? |
Advantages of distributed model of circulatory system over windkessel is 1. Effect of arterial distension on pressure wave velocity. 2. Pressure wave reflections from impedance mismatch. |
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What is the average shear rate and shear stress in human circulatory system? |
Average shear stress in human: 8 - 12 dynes / cm^2; (.8 - 1.2 N/m^2). Shear Rate |
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What are the advantages of the distributed model of the circulatory system over the windkessel model? |
Advantages of distributed model of circulatory system over windkessel is 1. Effect of arterial distension on pressure wave velocity. 2. Pressure wave reflections from impedance mismatch. |
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What is the average shear rate and shear stress in human circulatory system? |
Average shear stress in human: 8 - 12 dynes / cm^2; (.8 - 1.2 N/m^2). Shear Rate |
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At what rate the human body can clear itself off of the free hemoglobin |
The rate at which the human body can clear itself off of free hemoglobin is 20g a day. 64 (5 mg/dl/hg) by reticuloendothelial system |
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What is the only FDA approved application of TAH? |
FDA approve application of TAH is syncardia (freedom) |
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What are the advantages of receiving TAH prior to transplant? |
Advantages of receiving, TAH prior to transplantImmediate availability @ syncardia centerPatients recover rapidlyUp to 9.5 L/min through both ventricles74% bridge to transplant rateFaster bridge to transplantEliminate complication caused by a failing heartPatient body automatically adjusts blood flowReliability second to noneHospital Reimbursement |
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. Types of pacemakers |
Asynchronous Pacemakers - Repetition rate is independent of electrical activity of the heartSynchronous Pacemakers - Repetition rate is directly related to the electrical activity of the atriaRate Responding Pacemakers - Sensors that read rate and pulse |
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Types of electrodes |
Unipolar and bipolar |
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Atrial Synchronous pacemaker -principle of operation |
Atrial synchronous pacemaker - Principle operation. It detects the atrial electrical signal. Activities a stimulus pulse to the ventricles. Takes time delay into account so ventricles fill up enough |
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Cardioverter -principle of operation |
Treats irregular heartbeats that occurs in the ventricles. The operation decides to activate cardioverter. The ECG detects R wave, 30 ms delay, cardioverter sends the pulse (defibrillation), STOP, operator watches the result |
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Intra-aortic balloon pump - principle of operation |
Intra-aortic balloon pump - principle of operation placed in descending aorta, inflated during diastole. When aortic valve opens the balloons deflated. Deflation of the balloon decreases pressure “seen” by the heart balloon generates region of lower pressure to which blood can be easily moved by weakened heart. |
