Ischemic Heart Disease Flashcards
What are the 2 most important risk factors for the development of atherosclerosis in coronary arteries?
Male gender and increasing age
What are the 9 risk factors for IHD?
Male gender, increasing age, hypercholesterolemia, HTN, smoking, DM, obesity, sedentary lifestyle, and genetics
What are the first manifestations of IHD?
Angina pectoris, acute MI, and sudden death
___% of surgical patients have IHD
30
Define angina pectoris
Imbalance between coronary blood flow (supply) and myocardial oxygen consumption (demand)
________ angina partial occlusion or significant (>70%) chronic narrowing of a segment of coronary artery
stable
What are the results of adenosine and bradykinin release in angina pectoris?
- Cardiac nociceptors
- Afferent neurons
- T1-T5 sympathetic ganglia
- Slow AV conduction
- Decrease cardiac contractility
Who is likely to present with ischemia with symptoms other than chest pain?
DM and women
What can cause angina in anesthesia?
hypotension
_________ is the most common cause of impaired coronary blood flow resulting in angina pectoris
Atherosclerosis
What are other causes of angina besides coronary obstruction?
myocardial hypertrophy, severe aortic stenosis, or aortic regurgitation
What are the symptoms of an MI?
Retrosternal chest pain, pressure, heaviness (dermatome C8-T4)
Radiates to neck, left shoulder, left arm, or jaw - Occasionally to back or down both arms
Shortness of breath, dyspnea
Lasts several minutes
What are 3 inducers of angina?
Physical exertion, emotional tension, and cold weather
Differentiate between chronic stable vs unstable angina
Stable - CP that does NOT change in frequency or severity in a 2-month period
Unstable - CP inc in frequency and/or severity without increase in cardiac biomarkers; new-onset angina that is severe, prolonged, or disabling
- angina at rest lasting > 10 min
What are the most dangerous causes of CP?
aortic dissection, PE, and MI
How is angina diagnosed?
- 12 lead ECG
- Exercise Stress Test
- Nuclear stress imaging
- echocardiography
- coronary angiography
Nuclear stress imaging has _______ sensitivity than exercise testing for detection of IHD
greater
ST segment depression is characteristic of ____________ ischemia
subendocardial
What does T wave inversion indicate on an ECG?
shows previous/old MI
- T wave that was inverted goes back to normal (pseudonormalization) = new MI
Do patients with typical ECG evidence of AMI need an echo?
no
Exercise stress tests have ___% sensitivity
75
Which diagnostic test is useful in patients with LBBB, abnormal ECG, or uncertain AMI?
Exercise stress test
Why is an exercise stress test not always feasible to detect an MI?
Not always feasible d/t inability of pt to exercise owing to peripheral vascular or musculoskeletal disease, deconditioning, dyspnea on exertion, prior stroke, or the presence of CP at rest or with min activity
The _______ the degree of ST-segment depression, the ______ likelihood of CAD
greater, greater
How does an exercise stress test show a greater degree of ST changes?
1 mm horizontal or downsloping ST-segment depression during or 4 min after exercise.
How long are troponin levels elevated after an MI?
bumps in 3-4 hours, elevated for up to 2 weeks
How does nuclear stress testing distinguish between perfused vs ischemic areas?
Exercise inc difference in tracer activity between normal and underperfused regions → tracer activity shows inc coronary BF except regions distal to obstruction (dec)
What does the size of perfusion abnormality indicate in nuclear stress imaging?
significance of CAD detected
Nuclear stress imaging estimates ___ size and function as well as differentiates between ____ vs ____ MI
LV systolic; new vs old
What are the tracers used in nuclear stress imaging?
Thallium and technetium
What can be used to increase HR in nuclear stress imaging? Why?
Atropine, dobutamine, pacing - inc HR to create cardiac stress
What do Adenosine and dipyridamole do during nuclear stress imaging?
Produces cardiac stress - dilate normal coronary arteries but not atherosclerotic ones
Echocardiography shows what 2 things?
Wall motion abnormalities and valvular funciton
Echocardiography is ______ sensitive than exercise stress test
more
_______ provides the best information about the condition of the coronary arteries
Coronary angiography
For which patients is coronary angiography indicated?
pts with angina and survived sudden cardiac death, max medical therapy not working, need coronary revascularization, symptom recurrence after revascularization, unknown cause of CP and cardiomyopathy
Does coronary angiography measure the stability of plaque?
NO
What test diagnoses Prinzmetal (variant/spasm) angina?
coronary angiography
How can you assess the results of angioplasty/stenting?
coronary angiography
coronary angiography determines the _________ of occlusive disease
location
Define Prinzmetal (variant/spasm) angina. When is it likely to occur? How is it diagnosed on ECG?
- spasm: a sudden, temporary narrowing or tightening of a small part of an artery resulting in temporary ischemia
- typically occurs at rest and midnight to early morning
- diagnosed by ST-segment elevation during an episode of angina pectoris.
__________ plaques are likely to rupture and form an occlusive thrombus
vulnerable
Vulnerable plaques have a thin ________ and large _______ containing a lot of ______
fibrous cap, lipid core, macrophages
Is there a way to measure the stability of plaques?
no
What are non-pharmacological ways to reduce the risk of CAD?
- Cessation of smoking
- Ideal body weight
- Low-fat, low-cholesterol diet
- Regular aerobic exercise
- Treatment of hypertension
What is the goal for LDLs in CAD treatment?
LDL > 160 mg/dL (goal is >50% reduction or <70 mg/dL)
How does hypertension increase the risk of CAD?
Direct vascular injury, LV hypertrophy, and increases myocardial oxygen demand
List the 8 meds used for CAD drug therapy
ASA, platelet glycoprotein IIb/IIIa receptor antagonists, P2Y12 inhibitors, nitrates, beta-blockers, CCBs, ACE inhibitors, and statins
MOA and dose of ASA
- Inhibits COX-1 and subsequently TXA2
- TXA2 = prothrombotic, activates new platelets and inc aggregation
- Irreversible, platelet life span
- 75 – 325 mg/day
If a patient is allergic to ASA you can give a _______ for CAD treatment.
P2Y12 inhibitor
List 3 platelet glycoprotein IIb/IIIa receptor antagonists
abciximab, eptifibatide, tirofiban
What is the MOA of platelet glycoprotein IIb/IIIa receptor antagonists?
Inhibit platelet activation, adhesion, and aggregation
Which medications are P2Y12 inhibitors?
Clopidogrel (Plavix) and Prasugrel (Effient)
What is the difference between Plavix and Effient?
Effient is more potent and has higher risk of bleeding
What is the MOA of P2Y12 inhibitors?
- Inhibits ADP receptor P2Y12 and platelet aggregation (irreversible)
- D/C ~ 80% of platelets recover to normal function
- Prodrug - activated in liver (10-20% of people hypo/hyper-responsive)
Which drugs reduce the effectiveness of P2Y12 inhibitors?
PPIs
What is the MOA of nitrates?
- Dilate coronary arteries and collaterals
- Decrease peripheral vascular resistance → reduces LV afterload and myocardial O2 consumption
- Decreases venous return and preload → dec LV preload, EDV, and pressure → dec wall tension and myocardial O2 consumption
- Potential anti-thrombotic effects
Which drugs interact with nitrates?
Synergistic with beta-blockers/calcium channel blockers (greater antianginal effects)
When are nitrates contraindicated?
Aortic stenosis and hypertrophic cardiomyopathy
What is the only drug that prolongs life in CAD patients?
Beta-blockers - Decreases risk of death and reinfarction in MI pts
What kinds of patients should you use caution when administering beta-2 selective blockers?
Pulmonary - increased risk of bronchospasm in reactive airway diseases
Beta-blockers are anti-______, _______, and ________
Anti-ischemic, anti-hypertensive, anti-dysrhythmic
What is the MOA of beta-blockers?
Blockade of β1-receptors
- Dec heart rate → inc length of diastole and coronary perfusion time, dec myocardial oxygen demand
- Dec myocardial contractility
Which medication used to treat IHD is uniquely effective for decreasing frequency/severity of spasms?
CCBs
What is the MOA of CCBs?
Dilates coronary arteries, decreasing vascular SM tone, contractility, oxygen consumption, and systemic BP
Which medication is used to treat Prinzmetal’s/variant angina?
CCBs
CCBs are _____ effective than beta-blockers in decreasing incidence of MI
less
ACE inhibitors treat what 3 things?
- Hypertension
- Heart failure
- Cardioprotective
CCBs prevent _________, stabilize ___________ of re-perfused heart, and prevent the occurrence of ___________
ventricular remodeling
electrical activity
reperfusion arrhythmias
What is the MOA of ACE inhibitors?
Block conversion of ANG I to ANG II
- ANG II increases hypertrophy, fibrosis, vasoconstriction, and inflammation
- reducing ANG II decreases myocardial workload and oxygen demand
How do statins work to treat IHD?
Stabilize coronary plaques by decreasing lipid oxidation, inflammation, matrix metalloproteinase, and cell death
Which medication reduces mortality in noncardiac and vascular surgeries?
Statins
Revascularization options
Percutaneous coronary intervention or CABG
Revascularization is considered to treat IHD when the EF is less than ____%, the L main coronary artery is ___% occluded, or when an epicardial coronary artery is ___% occluded
40%
50%
70%
Which patients should have a CABG over a PCI?
L CAD, 3-vessel CAD, and DM with 2 or 3-vessel CAD
Describe the patho of ACS
- Acute or worsening imbalance of myocardial oxygen supply to demand
- Focal disruption of an atheromatous plaque
- Triggers the coagulation cascade
- Thrombin generation
- Arterial occlusion (partial or complete) by a thrombus
What are the 3 categories of ACS based on 12-lead-ECG and cardiac-specific biomarkers?
- STEMI
- Non STEMI
- Unstable angina
The majority of STEMIs are caused by
thrombotic occlusion of a coronary artery
What are the rare causes of STEMIs?
coronary occlusion caused by coronary emboli, congenital abnormalities, coronary spasm, or inflammatory diseases
Describe the thrombogenesis pathway
- Chemical mediators (collagen, ADP, epinephrine, serotonin) stimulate platelet aggregation
- Thromboxane A2 released and causes vasoconstriction, compromising coronary blood flow
- Glycoprotein IIb/IIIa receptors on platelets are activated → increase adhesiveness, growth, and stabilization of the thrombus
- Fibrin deposit makes the clot more resistant to thrombolysis
plaques that rupture and lead to acute coronary occlusion are ______ of a size that causes significant coronary obstruction
rarely
flow-restrictive plaques that produce chronic stable angina and stimulate development of collateral circulation are _____ likely to rupture
less
What criteria must be met to diagnose a STEMI?
- rise and/or fall of cardiac biomarkers (troponin) and evidence of MI indicated by one of the following…
- symptoms of ischemia
- ECG showing new ischemia (ST changes)
- pathologic Q waves on ECG
- imaging evidence of new myocardium loss or regional wall motion abnormality
- angiography or autopsy identification of intracoronary thrombus
New unstable angina may radiate as high as the _____ but no lower than the ______
occipital area, umbilicus
What percentage of patients have no/mild pain at the time of AMI?
25% - elderly and DM
What are S/S of ischemia?
anxious, pale, diaphoretic, tachycardia, hypotension, and dysrhythmias
Development of a Q wave on ECG is more dependent on the ______ of infarcted tissue than the _______ of the infarction
volume, transmurality
Troponin levels increase within ______ and remain elevated for _____ after an MI
3 hours, 7-10 days
Troponin is ______ specific than CK-MD for MI
more - CKMB for all muscles, not just cardiac
Does troponin level correlate to the size of MI?
yes - higher troponin = larger MI
What is the primary goal in the management of STEMIs?
To reestablish blood flow in the obstructed coronary artery as soon as possible
How can you differentiate between pericarditis and angina?
Pericarditis - ST elevation in all leads, relieved by position change, increase WBCs, infection symptoms, CRP elevated
How can you differentiate between PE and angina?
blood gas, confusion, air hungry
What is the lifespan of platelets?
7-14 days
What blood test can be used to evaluate clots?
TEG - a point-of-care test that measures the viscoelastic properties of blood clots, providing information about the speed, strength, and stability of clot formation.
What are the differences in effects of esmolol vs metropolol?
- esmolol - effects HR but not contractility
- metropolol - effects contractility but not HR
When are thrombolytics indicated?
STEMI only - not unstable angina or NSTEMI d/t increased mortality
What are the risks of angioplasty?
destruction of endothelium and vessel injury → area prone to thrombosis
bleeding (DAPT)
How long do patients have to be on DAPT after PCI?
balloon angioplasty - 2–3 weeks
bare-metal stent placement - 12 weeks
drug-eluting stent - a full 1 year or longer
What is DAPT?
Dual Antiplatelet Therapy (DAPT) - ASA with P2Y12inhibitor
_________ discontinuation is the most significant independent predictor of stent thrombosis
P2Y12inhibitor
Which medications should be d/c’d prior to elective surgery in patients on DART?
- D/C to reduce bleeding risk
- 5 days - clopidogrel or ticagrelor
- 7 days – prasugrel
Continue ASA if possible
When are beta-blockers contraindicated?
HF, low CO, risk of cardiogenic shock, heart block
What meds should be avoided in patients with a STEMI?
Glucocorticoids and NSAIDs (except for aspirin)
Thrombolytic therapy should be initiated within _____ min of hospital arrival and _____ hours of symptom onset
30-60 min, 12 hours
PCI should be initiated within _____ min of hospital arrival and _____ hours of symptom onset
90 min, 12 hours
When would PCI be preferred over thrombolytics?
- Contraindication to thrombolytic therapy
- Severe HF and/or pulmonary edema
- Symptoms present for 2 - 3 hours
- Mature clot (less likely to be lysed by fibrinolytic drugs)
When is emergency CABG performed?
- angiography reveals coronary anatomy that inhibits PCI
- patients with a failed angioplasty
- evidence of infarction-related ventricular septal rupture or mitral regurgitation
Why is a neuraxial blockade not encouraged in patients on DAPT?
inc risk of spinal hematoma during time of catheter placement and removal
When can a patient have elective surgery after PCI?
angioplasty w/o stenting - 2–4 weeks
bare-metal stent placement - 4-12 weeks
coronary artery bypass grafting - 6-12 weeks
drug-eluting stent - 6-12 months
What does a carotid bruit indicate?
cerebrovascular disease
__________ can indicate attenuated ANS activity because of treatment with antihypertensive drugs
orthostatic hypotension
What are 2 signs of RV dysfunction?
JVD and peripheral edema
What sounds on auscultation can indicate LV dysfunction?
S3 or rales
Silent MI usually occurs at a ___ HR and BP
lower than during exercise-induced ischemia
Why should beta-blockers be continued for surgery? Ideal HR?
to prevent rebound hypertension and tachycardia, 50-60bpm
What meds can be administered to treat excessive bradycardia in patients on beta-blockers?
Glycopyrrolate > atropine to treat excessive bradycardia
- glycopyrrolate has less inc in HR than atropine
- neostigmine given with glycopyrrolate to balance
What medication is the antagonist for excessiveβ-blocker activity?
Isoproterenol
What should you expect in a patient undergoing anesthesia taking α2-Agonists? D/c before surgery?
Decrease sympathetic outflow, blood pressure, and heart rate
- don’t d/c
When should ACEi be d/c’d before surgery? What meds can be given to combat hypotension?
24 hours
- vasopressin, ephedrine, phenylephrine
What is the goal for blood sugar during anesthesia?
< 180 mg/dL
What determines low vs elevated risk on the RCRI scale?
- Low risk - <1%
- ≤1 RCRI risk factor
- Elevated risk - >1%
- > 2 RCRI risk factors
metabolic equivalent of task
Rate of energy consumption at rest
1 MET = 3.5 mL/kg/min
What are the concerning active cardiac conditions undergoing surgery?
Unstable coronary syndromes (MI < 60 d), severe angina, decompensated HF, severe valvular heart disease, significant dysrhythmias
What are the anesthetic goals for patients with CV history?
Prevent myocardial ischemia (optimize supply and reduce demand)
Maintain BP and HR w/in 20% of normal awake baseline
- take your time!
What can decrease oxygen delivery?
dec coronary blood flow, hypotension, tachycardia, hypocapnia, coronary artery spasm, decreased oxygen content, anemia, arterial hypoxemia, oxyhemoglobin dissociation curve shifted left
What increases oxygen requirements?
SANS stimulation, tachycardia, hypertension, increased myocardial contractility, increased afterload and preload
What meds can reduce sympathetic response to intubation?
Laryngotracheal lidocaine, IV lidocaine, esmolol, fentanyl, remifentanil, and dexmedetomidine
What is the drug of choice for tachycardia in CV problems?
esmolol
Why use neo instead of ephedrine?
ephedrine - inc BP and HR
neo - dec HR, inc BP
Cardiac leads for R/L coronary?
Leads II (R coronary) and V5 (L coronary)
