KIN 407 Midterm 2 Flashcards
Acute coronary artery syndromes?
Stable angina pectoris, unstable agina, acute MI, sudden cardiac death
What determines myocardial oxygen supply?
O2 content from coronary blood flow…coronary perfusion pressure, coronary vascular resistance (external compression and intrinsic regulartion via neural innervation, endothleial factors, and local metabolites)
What determines myocardial oxygen demand?
Wall stress and heart rate and contractility
Situational triggers of coronary events?
Physical exertion, emotional excitement or anger, large meal, cold weather (vasoconstriction)…all constrict arteries or rupture plaque
Stenosis at 70% versus 90%?
70%, BF is adequate at rest but becomes a challenge with stress…stenosis at >90% is insufficient BF at rest
5 types of angina pectoris?
Stable angine, silent angina, variant angina, unstable angina, postprandial angina
What is stable angina?
chronic pattern of angina, narrow lumen, vasoconstriction, relieved by rest, NO PERMANENT DAMAGE
Variant angina?
pain at rest, coronary artery spasm, but if severe enough can cause sudden cardian death. “Prinzmental angina”
Silent angina?
No symptoms/pain, detected by EMG, diabetics, women and old people are most common, damage to microvasculature of heart
unstable angina?
Increased frequency and duration of angia, platelets –> thrombus, pain during less exertion or rest, high freqency of progression to an MI
Postprandial angia?q
After a meal, a marker of extensive CAD and can precipitate to an MI
Consequences of ischemia?
1) Swithch from aerobic to anaerobic metabolism because of inadequate O2 2) Impaired contraction (both systolic contraction and diastolic relaxation…both require O2) 3) Increased LV diastolic pressure –> pulmonary congestion (dyspnea) 4) Waste products (esp. H+) activate peripheral pain receptor in the C7-T4 causing angina and triggers arrhythmia 5) Increased SNS, leading to sweating, high HR and BP
Symptoms of angina?
Chest pain (pressure, discomfort, tightness, burning, heaviness. location is diffuse not localized). tachycadria, sweating, nasusea, fatigue and weakness. ECG changes
Diagnosis of ischemia/angina/
history, physical exam, ECG, stress testing, nuclear imaging studies, echocardiogram, coronary angiography
Treatment for ischemia?
restore O2 supply balance, pharmacology, revascularization, coronary bypass sutgery
What is an MI?
A myocardial infarction…death of tissues (myocardial necrosis)…prolonges cessation of blood supply…acute thrombus,,,depends on amount of occlusion and extent of collateral circulation…damage is IRREVERSBLE
SIgns of unstable angina?
ST depression, no tissue damage, partial occlusion, no necrosis of tissues, no TN-T or TN-I in blood
Signs of a non-St-elevation MI (NSTEMI)?
ST depression, damage, partial occlusion, necrosis of tissue, TN-I an TN-T in blood
ST-Elevation MI (STEMI)?
ST elevation, damage (most), complete occlusion, necrosis of tissues, TN-I and TN-T in blood
What is a transmural infarct?
Entire thickness of myocardium, and results from total prolonged occlusion
What is a subendothelial infarct?
Inner most layer of the myocardium…some contraction may still occur
Amount of tissue affected from a MI depends on?
Mass of affected myocardium, magnitude and duration of impaired flow, O2 demand at that region, collateral circulation (more collaterals = less damage), the degree of tissue response that modifies the ischemic response
Metabolic changes occur hoe long after blood flow decreases?
Decrease function in 2 minutes
When does irreversible cell injury occur?
20 minutes
WHen does edema occur in an infarcted heart?
4-12 hours
When do wavy myofibrils appear after an infarct?
1-3 hours
When does total necrosis of cardiac tissue occur following an infarct?
2-4 days
When does clearing of the necrotic myocardium happen in an infarcted area?
5-7 days
WHen does the deposition of collagen to form scar tissue begin in the infarcted heart?
7 weeks
What are the functional alterations of ischemia?
Systolic dysfunction, wall motion abnormalities, diastolic dysfunction, ventricular remodelling
Ventricular remodeling due to ischemia causes what?
Thinning and infarcted tissues (increases wall stress, impairs systolic contraction, increases likelihood of aneurysm), dilation of noninfarcted wall (increases Q at first, but leads to heart failure/arrhythmias later on)
Systolic dysfunction due to ischemia is caused by?
Lack of ATP and death of cells…leads to impaired ventricular contraction
What are the wall motion abnormalities caused by ischemia?
Hypokinetic (low functional movement), Akinetic (no movement), Dyskinetic (outward bulge instead of contracting)
Diastolic dysfunction due to ischemia is caused by?
lack of ATP…impaired diastolic relaxation, which causes the intraventricualr pressure to being to rise leading to dyspnea
What are the 4 ways a MI is diagnosed?
Patient’s symptoms, Acute ECG abnormlaities (ST segment elevation, T wave inversion, Q wave developments), Detection of specific serum markers of necrosis (cTNI, cTNT), Imaging
Clinical features of a MI?
chest pain, shortness of breath, anxiety, weakness, tiredness, sweating, dizziness, palpitations, nausea, vomiting
Sympathetic effects of a MI?
triggered by pain, diaphoresis, cool/clammy skin, anxiety, dizziness, palpitations
Parasympthetic effects of a MI?
nausea, vomiting, weakness
WHen do serum markers appear in the blood following an MI, when do they peak?
3-4 hours after pain, peak 18-36 hours
Main serum markers of a MI?
cTNT and cTNI
Imaging techniques for discovering a MI?
echocardiography, stress test, angiography
Immediate care for a MI?
ECG, pain control, pharmacology (anti-ischemic, anti-thrombotic, anticoagulant), adjuvant (statin and ACE inhibitors)
What is the fibrinolytic therapy for acute treatment of STEMI?
Recombinant tissue-type plasminogen activator such as Alteplase, reteplase, or tenectplace, which all stimulate the natural fibrinolytic system to break down blood clots. Complications = bleeding
Triggers of sudden cardiac death?
transient ischemia, hemodynamic fluctuations, neurovascular fibrillation, environmental factors
Predominant cause of sudden cardiac death in adults?
CAD…plaque disruption with thrombus occlusion
Triggers of CAD that lead to sudden cardiac death?
wall stress, flexing of artery, augmenting catecholamine-induced platelet aggregation, coronary artery spasm/variant angina
hypertrophic cardiomyopathy and sudden cardiac death?
inherited condition…enlargement of the cells in the heart wall, especially the left ventricle, thickens the heart muscle, decreases stroke volume, inefficient contraction of sarcomeres, can cause electrical conduction disturbances and lethal heart rhythms
3 rules of cardiac vectors?
- Toward + electrode = upright deflection 2. away from + electrode = downward reflection 3. Perpendicular to + electrode = biphasic deflection or no signal
dEPOLARIZATION towards a negative electrode = ?
negative deflection
depolarization towards a positive electrode = ?
upward deflection
DIrection and magnitude of an ECG depends on?
how the electrical forces are aligned to a specigic reference axis (ECG leads)
Positive and negative electrode of lead 1?
Positive on left arm, negative on right arm
Positive and negative electrode on Lead 2?
Positive and left leg, negative on right arm
Positive and negative electrode on Lead 3?
Positive on left leg, negative on left arm
Location of aVR?
Right arm
Location of aVL?
Left arm
Location of aVF?
Left leg?
Criteria for a normal P wave?
<0.25 mV high
Criteria for a normal PR interval?
0.12-0.2 s
A PR internval that isn’t between 0.12-0.2 s means?
Problem between the SA node and AV node
Criteria for a normal QRS complex?
0.12s
Criteria for a normal corrected QT inteval?
0.35-0.44s
Criteria for a normal ST segment?
should be isoelectric
Criteria for a normal T wave?
same orientation as QRS
What is an R wave?
A positive reflection
What is any positive reflection called?
A R wave
What is a Q wave?
A negative deflection before an R wave
What is a S wave?
A negative deflection after an R wave
Standard calibration of an ECG reading?
10 mm - 1 mV, 1 mm = 1 mV, 1 mm = 0.4 s at 25 mm/s
Summary of steps for 12 lead analyses?
1) Check rates 2) Rhythm 3) Axis–calculate mean QRS 4) hypertrophy 5) ischemia and infarction 6) conclusions
Quickest way to determine heart rate?
1500/#mm per beat
PR interval greater than 0.2s?
AV block
PR internval less than 0.12?
pre-excitation syndrome
QRS greater than 0.12s?
Bundle branch block
QTc greater than 0.44?
Long QT syndrome
How to correct for QT (how to calculate QTc)?
QT/ square root of R-R interval
If +ve in Lead 1 and aVF?
normal axis
If +ve in Lead 1 and -ve in aVF?
left axis deviation
If -ve in Lead 1 and +ve in AVF?
right axis deviation
Normal axis range?
-30 degrees to 90 degrees
Left axis deviation range?
-30 to -90 degrees
Right axis deviation?
90 to 150
Possible cause of left axis deviation?
Left ventricular hypertrophy
Possible cause of right axis deviation?
Right ventricular hypertrophy, left ventricular infarction
Right Atrial Hypertrophy showings in an ECG?
Tall peaked waves >2,5 mm in LEAD 2. Diphasic P waves with initial phase larger than terminal phase in V1
Left atrial hypertrophy showings in an ECG?
Wide notched P wave (>0.12 s wide, >1 mm) in Lead 2. Diphasic waves with initial phase smaller than terminal phase in V1.
Right ventricular hypertrophy showings in an ECG?
R/S ratio >1.0 in V1. Right axis deviation.
Left ventricular hypertrophy showings in an ECG?
R wave in V5+ S wave in V1 = >35mm. Left axis deviation.
Ischemia showings in an ECG?
ST segment depression >0.5 mm (most common) OR T-wave inversion
Injury or infarction showings in an ECG?
ST-segment elevation above isoelectric line >1mm. Significant Q wave that is 1/4 the height of R wave or Q >0.04 s duration
What is the criteria for a significant Q wave?
1/4 height on R wave or Q >0.04s duration
Acute MI signs in an ECG?
ST segment is still elevated
Old MI signs in an ECG?
ST segment normalized, significant Q wave persists.
Significant Q waves must be found in what leads for a lateral MI?
Lead 1, aVL, V5, V6
Significant Q waves must be found in what leads for an inferior MI?
Lead 2 and 3, and aVF
Significant Q waves must be found in what leads for an anterior MI?
V1, V2, V3, V4
What is sinus bradycardia?
HR <60 bpm…normal if well-trained or caould be pathological (bad pacemaker) or drug-induced
What is sinus tachycardia?
HR > 100 bpm. Could be normal id from exercise or pathological if there is a fever, hypoxia, or anemia. QT waves blend together.
What does sinus arrythymia look like on an ECG?
Normal PQRST (each complex looks the same), but the rate varies
What does a wandering pacemaker ECG look like?
P-shape changes (something else in the atria besides SA node is firing). QRST is consistent.
What does atrial fibrillation look like on an ECG?
No P-wave, multiple atrial firings (just quivering, so no real P-wave), very varying QRS.
What is the biggest concern with atrial fibrilllation?
Low CO, so feel lightheaded. When the blood isn’t being pumped from the hear, it sits there and begins to coagulate. If the heart goes to a normal rhythm, clot is ejected = stroke
What are premature beats?
beats that occur early, followed by a pause