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110 Cards in this Set

  • Front
  • Back
Define Automaticity
The ability of cardiac cells to initiate an electrical stimulas
Define Excitability
The ability of myocardial cells to respond to an electrical stimulas
Define Conductivity
The ability to transmit the impulse from one cell to the next
Define Contractility
The ability of myocardial cells to shorten (contract) in response to an electrical stimulus
Define Refractoriness
The INABILITY of cells to respond to an electrical impulse if they have not recovered from the previous impulse.
What is the difference between th absolute and relative refractory periods?
During the absolute refractory period the heart will not respond to any stimulus of any magnitude however during the relative refractory period the heart will respond if the stimulus is strong enough.
What is cardiac output and what is its normal range? How do you calculate this?
The volume of blood pumped by the heart in one minute which is usually 4-7L. CO=(SV)(HR)
What is the difference between the CO and the CI (cardiac index)? How do you calculate this?
CI is an adjustment made to the CO based on body size in terms of body surface area (BSA). CI= CO/BSA
What is the heart rate?
The number of times the ventricles (specifically the LV) contracts in one minute.
What is the stroke volume?
The amount of blood ejected with each contraction of the LV?
What is preload?
The amount of myocardial stretch at the end of diastole. It is the volume part of the hearts work.
What is Starling's Law?
The greater the myocardial stretch, the greater the strength of the contraction.
What determines preload or in other words the amount of myocardial stretch and how does this effect the CO?
The Left Ventricular End Diastolic Volume (LVEDV) determines preload. More volume = more stretch = stronger contraction = more SV= more CO
True or False. The myocardium can not be over stretched. Increased LVEDV always causes increased myocardial strength.
False. Over time the myocardium can be overstretched and will start to lose its effectiveness.
What is afterload?
The pressure the LV must overcome to eject blood into the aorta. It is the pressure part of the hearts work.
What is the "all-or-nothing" principle?
If the threshold potential is not achieved, an action potential does not occur.
What is the threshold potential of a cardiac cell?
About -60mv
What happens during phase 0 or depolarization?
The cell is stimulated, Na+ channels open and Na+ floods into the cell leading to a rise in membrane potential (Na+ is positively charged) and goes from -90mv to +20mv
What happens during phase 1 or early repolarization?
This is the inital change in membrane potential from +20mv to 0mv when the Na+ close and some Cl- enters the cell.
What happens during phase 2 or the plateau phase?
This is the part of the action potential that is about 0mv when Ca+ channels open and Ca+ enters the cell.
What happens during phase 3 or rapid repolarization?
This is when the action potential returns to the resting membrane potential during which K+ rushes OUT of the cell.
What happens during phase 4?
This is when the cell is at resting membrane potential and would not be able to respond to a stimulus due to the ionic balance (Na+ inside and K+ outside).
What is the Sino-atrial (SA) node, how many times a minute does it depolarize where is it located?
The SA node is the normal pacemaker for the heart and depolarizes at a rate of 60-100 times/min. It is located near the area where the SVC enters the RA.
What are the internodal pathways?
They deliver the impulse from the SA node to the RA.
What is the Bachmann's bundle?
Bundle which delivers the impulse from the SA to the LA.
What is the atrioventricular (AV) node, where is it located, what is its rate of depolarization?
The AV node slows the impulse slightly as is moves through the conduction system. It also serves as a back up pacemaker if the SA node fails, but at a slower rate of 40-60/min. It is located near the junction of the atria and the ventricles.
What is the bundle of His?
It is in conjunction with the AV node and helps slow the rate of impulse transmission while delivering the impulse to the ventricles.
What are the bundle branches?
There are two: LBB and the RBB. They rapidly transmit the impulse from the bundle of His through the ventricles to the purkinje fibers.
What are the purkinje fibers?
These fibers RAPIDLY transmit the impulse to the ventricular myocardium simultaneously to ensure a coordinated effective contraction. If higher areas of the conduction system fails the ventricles could assume pacemaker function but only at a rate of 20-40 times/min.
What does the horizontal axis of the EKG monitor paper? What is the amount between two vertical lines? Between two dark vertical lines?
It registers time. Between two lines is 0.04 seconds. Between two DARK lines is 0.2
What does the vertical axis of the EKG stripi register? What is the amount between two lines? Between two DARK lines?
It registers the voltage and is 0.1mv between two lines and 0.5mv between two DARK lines.
What is the electrical and mechanical actions of a P wave? What does it look like on a monitor strip?
The P waves signify atrial depolarization and atrial contraction. The P waves are generally small, round positive deflections from the baseline and occur before the QRS complex.
Why are P waves round in shape rather than sharp spikes?
Because there is a slight delay between depolarization of the right atria and the left atria.
What is the PR interval and what does it represent? What is the normal range for the PRI?
The period of time from the beginning of the P wave to the beginning of the QRS complex and represents the time from atrial depolarization to the start of ventricular depolarization. The normal range is 0.12 to 0.20 seconds.
What is the electrical and mechanical actions of the QRS complex? What does it look like and what is the normal range?
The QRS complex represents ventricular depolarization and ventricular contraction. It is usually the largest part of the tracing on the EKG tracing and ranges from 0.04 to 0.10 seconds.
What is the T wave?
T waves represent ventricular repolarization and are usually a upright deflection following the QRS complex.
What are the 5 questions a nurse should ask when assessing monitor strips?
1. Are there P waves? Is the morphology consistent? Rate/rhythm?
2. Is there a P wave in front of each QRS complex?
3. What is the duration of the PRI?
4. What is the duration of the QRS complex?
5. What is the ventricular rate/rhythm?
Which arteries are the only ones to fill during diastole?
The coronary arteries
What are some s/sx of cardiac problems?
chest pain, dyspnea, diaphoresis, nausea, vomiting, dizziness, fatigue, palpitations, flutterings, edema, weight gain
Describe the difference between the pain caused by an MI and the pain caused by pericardial issues.
MI tend to be vice like pressure, squeezing, "elephant on chest." Pericardial issues tend to a stabbing sharp pain.
What is tachycardia and what kinds of problems can it cause?
>100 bpm which increases the workload of the heart and requires more O2. It can cause problems with coronary artery perfusion because diastole is not long enough for the arteries to fill. So the heart is requiring more O2 but less is getting to it.
What is Bradycardia and what kinds of problems can it cause?
<60 bpm. Coronary perfusion is okay, but cardiac output and thus cardiac perfusion may be compromised.
What are premature complexes?
Some spot, outside the SA node in the conduction system becomes irritable and initiates an impulse. The three types are PAC, PVC and PJC
What is and escape rhythm?
If the SA node fails another spot in the conduction system has to take over such as the AV node or the ventricles.
What are two types of temporary pacemakers?
External (noninvasive) and Internal (invasive)
Describe the two types of internal temporary pacemakers.
Transvenous: An electrode is threaded through the sub-clavian artery and into the rt. ventricle where it is hooked to the endocardium while external wires are hooked to a machine. Epicardial: bare wires are left in the epi/myocardium after heart surgery in case the person needs it. Insulated part of the wires are left in a coil on chest.
Describe permanent pacemakers.
They are usually transvenous and sit in a pouch formed in the subQ tissue. Leads are threaded into the rt. atrium from pacemaker.
Why are pacemaker electrodes placed into the right side of the heart?
Because the right side has less pressure and it is easier to access.
What is the difference between a single and a dual chambered pacemaker?
Single chambered pacemakers are attached to either the atrium or ventricle where a dual chambered pacemaker is attached to both.
When is a single chambered atrial pacemaker used?
When the conduction system is intact (no blocks), but the SA node is inadequate at being the pacemaker.
When is a single chambered ventricular pacemaker used?
When pts heart rate needs to be increased (as with bradycardiac problems or a block)
How does a dual chambered or atrioventricular sequential pacemaker work?
Atrial lead fires, then ventricle lead fires. This maintains normal heart rhythm and the atrial kick which thus increases CO
What is the difference between synchronous and asynchronous pacemakers?
Synchronous pacemakers have a pace set at a certain rate and if the pts heart rate maintains at this rate then the pacemaker does nothing. Asynchronous pacemakers however will fire at a set rate regardless of what the pts heart rate is. There is a risk for R on T wave phenomenon which can lead to V-fib so these are rarely used.
What are some complications of pacemakers?
Infection, Ectopy, failure to capture, undersensing, oversensing, and electromagnetic interference.
What is Ectopy?
During insertion (or afterwards) of a pacemaker the electrodes might bump the ventricles and cause a PVC
What is failure to capture?
Pacemaker fires, but there is no depolarization. The electricity may need to be turned up.
What is undersensing?
Pacing continues at a set rate even though the pts heart rate is above the set rate (can lead to R on T problems)
What is oversensing?
Pacing does not occur even though pts heart rate is below set rate. It may be picking up other electrical activity from other parts of the body.
What things do pts need to know about their pacemakers?
What the rate is, avoid using arm for several days, monitor site, and check pulse EVERY day at least once.
What is infective endocarditis and what are some causes?
A bacterial or fungal infection of the endocardium or valves caused by open heart surgery, cardiac defects, drug abuse (needle sharing), central lines, pacemakers, dialysis, or tongue piercings.
What are the s/sx of endocarditis?
fever >103, anorexia, weight loss, fatigue, murmur, symptoms of heart failure, positive blood cultures, petechiae, etc.
What are some interventions for endocarditis?
antibiotics, surgery, rest and good oral hygiene, combat immobility (TED hose, ROM, turning), monitoring closely, pt teaching.
What is pericarditis?
Inflammation of the pericardium
What are the types of pericarditis and their causes?
Acute: caused by viral or bacterial infection, trauma, MI, idiopathic
Chronic: caused by TB or radiation theraphy
What are some of the s/Sx of pericarditis?
sharp, substernal, pleuritic pain which can be positional. pericardial friction rub, may or may not have a fever.
What are some interventions for pericarditis?
NSAIDS, antibiotics
What are some possible complications of pericarditis?
Pericardial effusion: build up of fluids in pericardial sac or Cardiac tamponade: excess buildup of fluid in sac to the point that it cannot stretch any more. Heart is squeezed leading to a decreased c/o and eventually no c/o
What are some s/sx of cardiac tamponade?
weak or absent pulses, low b/p, JVD with no pulmonary congestion, muffled or absent heart sounds
What are some interventions for cardiac tamponade?
Pericardiocentesis, pericardial window, or pericardectomy
What is anginapectoris and how is it caused?
It is pain in the heart caused by narrowing of the lumen which doesn't allow the heart to get enough of the blood and O2 that it needs
What is stable angina?
Predictable pain. Pain that is not changing, it's consistent in pts lives. eg. Activity causes heart to need more O2 so they experience pain, but upon rest it goes away.
What is unstable angina?
Some aspect of the pain is changing. It's lasting longer, more frequent, more intense, occurs with rest, or radiates to different areas.
What sort of ECG changes might you see with angina?
inverted T waves, ST depression, or nonspecific ST wave changes
What is a MI and what causes it?
A heart attack which occurs when there is a sudden interruption of blood supply which decreases O2 supply to the heart. Possible causes are: atherosclerosis, coronary artery spasm, embolus, platlet aggregation, etc.
What is a STEMI?
MI in which the artery blockage does not extend the full thickness of the myocardium
What types of ECG changes might you see with a STEMI?
elevated ST segments
What is a transmural MI?
full thickness MI
What are the affected zones of an MI?
Zone of necrosis: center zone which is not functioning and will become dead scar tissue, can't be repaired
Zone of injury: Middle zone that is injured but once O2 is restored the cells will be repaired and will function again
Ischemia: Outer area that has minor tissue involvement and damage. Will repair and function again.
What kind of pain does an MI cause?
Vice-like, what's them up at night and starts with virtually no activity, nothing relieves the pain.
What kind of lab changes will you see when someone has had an MI?
CPK-MB will be increased for up to 3 days after the MI
Tropinin will be increased f1or up to 1 wk after an MI
Why is it important to check CPK-MB levels every 3 hrs. for 24hrs to R/O an MI?
To try to catch its peak if there was an MI. CPK-MB will peak at 12-24hrs. and normalize within 2-3 days.
What do ECG's tell us about an MI?
They tells us where the MI occurred (posterior, anterior, etc.)
What are some interventions for an MI?
Pain relief (meds), TPA, Rest, emotional support, monitor (dysrhythmias, b/p, pulse, heart & lung sounds, wt., edema, I&O, etc.), pt. education, med/surg mgmt
What are some surgical managements for an MI?
Percutaneous translumenal coronary angioplasty (balloon threaded through artery), coronary artery bypass graft (CABG), stents
What are the different classifications given to patients with a MI risk and how are they treated?
Low: treated conservatively (meds, stress test, etc.)
Mod: treated more aggressively
High: treated very aggressively with invasive treatment (meds, monitoring, early tx important, catherization, etc.)
What sort of meds will be given to a pt with a MI?
Pain/angina (nitro, morphine, etc.), Antiplatelets (asprin, heprin, plazix, GPIIb & IIIa inhibitors), Ace-inhibitors to decrease b/p, beta-blockers
What is heart failure?
Inability of heart to pump enough blood to meet the demands of the body
What causes heart failure?
MI, valve problems, infections/inflammatory process, pulmonary hypertension, etc.
What is high output heart failure?
The periphery tissues demand more blood then the heart can handle
What is low output heart failure?
The heart fails as a pump (MI or myopathy)
What is systolic heart failure?
The heart does not contract with enough force to meet the demands of the body (ejection fraction <40%)
What is the ejection fraction?
The % of blood ejected with each contraction, 50-70% is normal.
What is diastolic heart failure?
When the L ventricle won't relax enough during diastole, which decreases ventricle filling, stroke vol. and CO
What is left sided heart failure?
When the L ventricle fails to provide enough blood and so it backs up into the L atrium and then the lungs causing pulmonary edema
What is right sided heart failure?
R ventricle doesn't pump enough blood into the lungs and blood backs up into the venous system (peripheral failure)
What compensatory mechanisms does the body have for maintaining CO for some period of time?
Heart rate increases, stroke volume increases, atrial vasoconstriction, Na and water retention, and myocardial hypertrophy
What are the s/sx of left ventricular failure?
dyspnea on exertion or rest, SOB, orthopnea, parox, nocturnal dyspnea, pulmonary edema, cough, crackles, oliguria, palpitations, cardiomegaly, and decreased ejection fraction and ventricular function.
What are the s/sx of right ventricular failure?
Usually caused by left sided failure. Dependent edema, JVD, abdominal discomfort, nausea, hepatomegaly, nocturia, increased central venous pressure, cardiomegaly, and decreased ejection fraction and ventricular function.
What kind of interventions can we do for heart failure?
Ace inhibitors, diuretics, vasodilators, digoxin, beta-blockers, monitor respiratory system and cardiac system, sodium and fluid restriction
What is a stenotic valve?
narrow valve meaning its opening is not as wide as it should be and restricts blood from going through
What is a regurgant or insufficient valve?
The leaflets don't shut all the way or inverts backwards into atrium and blood back flows.
What are some of the causes of valvular heart disease?
Rheumatic heart disease, congenital problems, MI, endocarditis, etc.
What kind of murmur does mitral or aortic stenosis cause?
A diastolic murmur when the ventricles relax. lub-dub-swish
What kind of murmur does mitral or aortic regurgitation cause?
A systolic murmur when the ventricle is contracting. lub-swish-dub
What are some interventions we can do for valvular heart disease?
digoxin, O2 therapy, education, coumadin, reconstruction (repair or replace with mechanical or prosthetic valve), activity restrictions, extra rest, dietary considerations (low Na and fluid restrictions)
What is peripheral arterial disease?
Disorder that impedes arterial flow (ie. vasospasm, thromboembolic event)
What are some s/sx of peripheral arterial disease?
s/sx will occur in femoral/popiteal area or calves, ankles and feet. Cramping type of pain that decreases with rest, cool extremities, bruits, weak pulses, ulcers, higher b/p in lower extremities
What usually causes peripheral arterial disease?
What types of things can we suggest to our patients to help with peripheral arterial disease?
Encourage pt to stop smoking, change positions frequently, exercise to point of pain, avoid constrictive clothing, weight loss, low fat diet, don't sit or stand for long periods, pain control, good skin, foot & wound care
What types of treatment is there for peripheral arterial disease?
Angioplasty, bypass graft, endartectomy, amputation, meds