week 5 Flashcards
what are the layers of the heart?
Epicardium , Myocardium , Endocardium
what is Stroke Volume ?
amount of blood ejected with each heartbeat, ml/beat
what is Cardiac Output?
amount of blood pumped by ventricle in liters per minute
what is Contractility ?
ability of the heart to contract in response to electrical impulse
what is After Load?
resistance to ejection of blood from ventricle
what is Preload?
degree of stretch of cardiac muscle fibers at end of diastole
what is Ejection Fraction?
percent of end of diastolic volume ejected with each heartbeat
recite the Conduction Pathway
1) depolarization begins at SA, 2) Intraatrial and internodal pathway to AV, 3) Delay impulse begins at AV for ventricle filling , 4) Bundle of His, 5) Left and right bundle braches , 6) Punkinje fibers
what is the SA node and where is it located ?
It is the primary pacemaker where the depolarization begins (electrical impulse) and its located at the top of the righ atrium
summarize the Cardiac Cycle?
1)Depolarization , active electrical activity and systole = contraction , 2) Repolarization, resting electrical activity and diastole = resting or filling phase
True Or False : mechanical activity preceds electrical activity
False, electrical activity preceds mechanical activity
what is the formula for Cardiac Output ?
CO (ml/min) = SV X HR
what is the average heart rate?
70 BPM
what is the average stroke volume ?
70-80 ml/beat
what is the average cardiac output ?
5000 ml/min
what is Stroke Volume affected by?
after load is affected by : systemic vascular resistance , pulmonary vascular resistance
contractility is affected by : catecholamine (increase) , SNS, medications (increase or decrease) , hypoxemia (decrease) , acidosis (decrease)
what does ECG do?
records cardiac activity , displays the hearts electrical impulse through the conduction system ,
what is the purpose of EKG?
diagnosing a variety of cardiac abnormality
what can an ECG indicate ?
electrical conduction , areas of ischemia , myocardial damage , LV hyperatrophy , electrolyte distrubances , drug toxicity
what are the small boxes in the ECG paper represent ?
0.04s
what does 5 small boxes represnt in ECG reading?
0.20s
what is the P Wave?
atrial depolarization , normal , no more than 3 boxes , means the impulse started at SA node
what is the QRS complex ?
ventricle polarization , Q wave : negative delflection after p wave , R wave : positive delflection after p wave , S wave : negative waveform after r wave , T : ventricle repolarization
Do P waves have intervals ?
yes , they lost between ventricles and it doesn’t show on the ECG
what is U wave ?
its between P and T wave
how long does PR intervals take ?
0.12-0.20s
what does short intervals mean ?
shorter than 0.12-0.20 , impulse from the AV junction ,
what does a longer interval mean?
It means it takes longer than 20s, first degree AV block ,
how long does a QRS interval take?
0.6-0.10 secs
what does a wide QRS interval indicate ?
a slowed conduction , bundle branch block (BBB) , ventricular rythem
what does a ST segment depression indicate ?
reciprocal changes , digoxin , ischemia
what does an elevated ST segment indicate ?
myocardial injury
what does inversion of T wave indicate ?
myocardial ischemia
how do you interpret rythms of on the ECG?
by rythmicity , rate (atrial & ventricular) , waveform configuration and location, intervals
what is rythmicity?
pattern of heart beats
when is P-P interval rythem regular?
when the distance between P-P intervals is equal
True Or Flase : P-P intervals are atrial
True.
when are R-R intervals regular ?
when the distance between the R-R intervals are equal
what is a regular rate in ECG?
1500 in small blocks , 300 in large blocks
what is an irregular rate in ECG?
6-second strip
what is Atherosclerosis ?
Its the accumulation of lipids and fibrous tissue in the atrial walls , it narrows the vessels causing a decreased blood flow to the heart
what are the CM of Atherosclerosis ?
chest pain, weakness , dyspnea , nausea
what is Angina Pectoris ?
episodes of paroxysmal pain or pressure in the interior chest by insufficient coronary blood flow
what is Stable Angina ?
predictable and consistant pain , occurs on exertion , relieved by rest or nitroglycerin
what is Unstable Angina (crescendo angina) ?
Increase in frequency and severity , may not be relieved by rest & nitroglycerin
what is Variant Angina ( Prinzmetal’s Angina) ?
pain when resting , with reversible ST-segment elevation , caused by coronary artery vasopasm
describe Angina Pain?
mild to severe , tightness - choking - heavy sensation , may radiate to : neck , jaw , shoulder , back or arms (usually left) , anxiety accompanies pain
what are other symptoms of Angina ?
Dyspnea , SOB , dizzines , nausea ,vomiting, typically subsides with rest of NTG ,
what is the treatment of Angina
it seeks to decreas myocardial oxygen demand and increase oxygen supply ( medications , oxygen, reduce & control risk factors , reperfusion therapy)
what are the medications given for Angina?
NTG, Beta-adrenergic blocking agent , calcium channel blocking agent (amlodipine) , Aspirin , Clopidogrel and ticlopidine, Heparin , Glycoprotein , antiplatelet
what is Myocardial Infraction?
an area of the myocardium is permanently destroyed
what causes Myocardial Infraction ?
by reduced blood flow in a coronary artery ,
what are the goals of MI treatment ?
minimize myocardial damage , preserve myocardial fucntion , prevent complicatipns
what are the medications given for MI ?
aspirin , NTG, morphine , beta-blockers , Angiotensin-converting enzyme inhibtors within 24hrs , bedrest , heparin
