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47 Cards in this Set
- Front
- Back
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Hemostasis |
The body's response to blood loss due to vessel injury. |
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What are the three steps to reduce/eliminate broken vessel hemorrhage (blood loss)? |
1. Vascular spasm: smooth muscle contraction due to exposed tissue and pain receptors 2. Platelet plug formation: platelets in blood are attracted to injury site by exposed collagen, and stick together and attract more platelets 3. Blood clotting: Fibrin pulls clot together, Ca produces shell/hardening of clot |
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Blood clots consist of: |
Entrapped RBC's, plasma, and platelets |
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Fibrinolysis |
- Clot removal by lysis (breaking up of fibrin molecules - Clots contains plasminogen, which is normally found in plasma - Tissue and blood contain enzymes that cover plasminogen to plasmin - Plasmin slowly dissolves clots by fibrinolysis |
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Intrinsic Blood Clotting |
- Begins with platelet attraction to injured (but intact) or inflames blood vessels - Also can occur from blood stagnation - Takes a long time to produce the clot, which is referred to as a thrombus |
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Atherosclerosis |
- A progressive build up of fatty deposits of cholesterol, lipoproteins, calcium, etc. on arterial inner linings - Blood supply is reduced/eliminated - Function of affected tissues is compromised (cells die) - Plague weakens walls and cause an aneurysm - Silent disease (takes decades) - Causes: hypertension, high cholesterol, smoking, diabetes |
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Arterial and Venous Occlusion |
Partial or total blockage of blood flow in an artery or vein by: - slow progressive build up of plague - thrombus from injury - >70% blockage is significant, >90% blockage is urgent |
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Pulmonary Embolism |
- Often caused by a blood clot coming up from the legs and blocking a pulmonary artery or vein - If massive, need to do something fast |
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Blood Flow flows from what to what? |
High pressure to low pressure |
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What's an AV fistula? |
- Artificial pathway from artery to vein - The doctor puts it in, and they will always have a constant access to blood for dialysis, etc. |
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Physics of Blood Flow (Poiseuille's Law) |
Small arteriole radius changes produce relatively large resistance changes Radius decreases, resistance increases and vice versa Heart valves normally provide low resistance to flow |
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Physics of Blood Pressure Control |
Small changes in systemic arteriole radii are the primary means to maintain systemic blood pressure near a mean of 100 mmHg Small arteriole radius changes produce relatively large resistance changes! |
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Where does most of the pressure drop occur in systemic circulation? |
Arterioles |
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Aortic Booster Pump |
- Pumping of the stored blood during diastole because of recoil - Provides blood flow to the capillaries during diastole - Arteries stiffen as aging occurs and the booster pump doesn't function as well |
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Laminar Blood Flow |
- Cross-section has a dome shaped velocity profile - The velocity at the center is the highest and the velocity at the edges (the walls) is smallest |
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Turbulent Blood Flow |
- Blood pathway restrictions can increase velocity above a critical value, and turbulence is created - Cross-section has unidirectional blood flow with eddies and vortices (twists and turns) - Examples of this are heart valve closure, plague or thrombus lesions, and blood pressure cuff use |
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Stagnant Blood Flow |
- Blood is stagnant - Atrial fibrillation, plague, etc. - Platelets stick together and initiate clotting - Thromboemboli can be fatal (pulmonary embolism, MI, or stroke) |
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When do you hear sounds with a blood pressure cuff? |
When the systolic pressure is slightly higher than the cuff pressure |
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Coronary Circulation |
- Flow rate increases in response to low oxygen, or increasing adenosine and CO2 - Systolic compression limits left coronary artery blood flow during systole (almost all flow to left occurs during diastole) |
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Atrial Electrical Pathways |
AV node: on floor of RA, back up pacemaker, picks up wave of excitation from atria and transmits to ventricles Specialized pathways: - Bachman's Bundle: conducts action potential directly to LA - Three internal pathway: conducts action potentials to AV node |
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Ventricular Electrical Pathways |
AV node: picks up wave of excitation from atria and transmits to ventricles Atrioventricular Bundle Rt and Lt Branches Perkinje Fibers |
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Fast Response Action Potential |
- Myocardial cells - Fast depolarization due to sodium gates opening quickly and then shutting quickly - Depolarization due to potassium diffusing out in potassium gates - Ca diffusion allows for a sustained ventricular contraction |
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Sarcoplasmic Reticulum |
In actin/myosin relationship, 80% of calcium comes from the sarcoplasmic reticulum but 20% comes from the interstitial spaces |
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Slow Response Action Potential |
- Nodal (S-A and A-V) cells - Ca diffusion depolarizes membrane during resting period (diffusion is slow) - Repolarization is also slow, due to delayed potassium diffusion |
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End Diastolic Volume |
Volume of chamber at end of filling |
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End Systolic Volume |
Volume of chamber at end of systole (pumping) |
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Chronotropic Response |
Ability of the heart to increase HR when needed and decrease HR when needed. |
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NYHA Classifications |
New York Heart Association Classifies cardiovascular symptoms: Class 1: no symptoms Class 2: symptoms on exertion Class 3: all the time symptoms Class 4: bedridden/unable to function |
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Pre-load and Stroke Volume |
Physiological increases of preload increases tension and contractility (strength of contractions when shortening). More blood is ejected or pumped from the heart chamber. (excess blood volume increases it, decreased blood volume lowers it) |
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After-load and Stroke Volume |
As after load increases, more tension is required to produce the higher outflow pressure needed to open the outflow valve. |
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Ejection Fraction |
- Characterizes the strength of cardiac contractions - Almost always expressed as a percent of LV emptying - Normal resting values are 50-55% - Resting and exercise values fall as cardiac disease progresses - Formula: EDV-ESV (stroke volume)/EDV * 100 - Lower the ejection fraction the sicker the patient |
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Heart Sounds |
- Made by the closure of valves - S1: LUBB- Closure of AV valves - S2: DUPP- Closure of semilunar valves |
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Law of LaPlace |
- Pressure in a vessel is directly related to the wall tension and inversely related to the vessel radius. - Smaller radii can withstand higher pressure - The left ventricle can withstand 5-6 times greater pressure than the right due to its smaller radii and thicker walls |
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Interval-Strength Relationship |
Longer-filling time produces stronger beats, and shorter filling time produces weaker beats. |
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Premature ventricular contractions produce ____________ beats followed by a ____________ beat? |
Weaker, stronger (weaker beat is due to less filling time, there is a pause and then the first normal beat after is usually stronger in order to compensate for the weak beat) |
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Cardiac Catheterization: Ventriculography |
Common intra-cardiac catheterization procedure that can: - sample tissue - measure pressure - electrical mapping - fluoroscopy (injecting dye to visualize flow, check for heart defects, etc.) |
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Introducer System |
- Large bore syringe needle used to access vein/artery - Introducer is a flexible sheath that eases catheter access/withdrawl - Remains in place throughout entire procedure |
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Guidewire |
- Very small and flexible wire - Provide a direct catheter pathway from access site to the target site |
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Dilator |
- Dilates vessel access and is inserted alone or along with introducer |
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Catheter |
- Flexible, hollow tube with/without diagnostic/therapeutic capabilities |
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Embolytic Protection |
- Distal embolytic filters or proximal occlusion methods help to prevent emboli from causing problems due to the catheter breaking off plaque or a clot forming at the site of broken vessels |
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Fluoroscopy |
An x-ray technique where a contrast media (dye) is injected into the bloodstream to visualize heart chambers, blood vessels, or tumors |
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Access Site Closure |
Hemostasis plug or compression device |
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Typical Catheterization Pathways to Heart |
- Arm - Wrist - Groin |
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Catheterization Access Factors (impact decision of where to access heart) |
- Catheter vs. arterial size - Ability to palpitate access artery - Distance to target site - Ability to maneuver catheter sure to longer blood path, tortuosity, or vessel deformity - Can access artery with needle or whether you need to cut down surgically (like in groin) |
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Swans-Ganz Catheter |
- Pulmonary artery catheter for measuring cardiac output, central venous pressure, pulmonary artery pressure - Inserted in peripheral veins through right heart with tip in pulmonary artery - Can be used to diagnose pulmonary artery hypertension |
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Risks/Complications of Cardiac Catheterization |
- Major Cardiac Adverse Event (MACE): 1-4% - Arrhythmias - Kidney failure - Cardiac Tamponade - Pneumothorax - Allergic reaction to dye - Coronary artery dissection, rupture, or abrupt closure - Access site complications |
