Ischemic heart disease Exam 2 Flashcards
What chemical mediators are released from ischemia? (2)
- Adenosine = vasodilator, decreases HR, nociceptor activation
- Bradykinin = inflammatory and pain, nociceptor activation
How does IHD usally present initially in someone who is undiagnozed? (3)
- Angina pectoris
- Acute MI
- sudden death (dysrhythmias)
What are the 2 most important risk factors for IHD?
- male gender
- increasing age
How are pain signals transmitted from an ischemic heart? Which nerves?
- Adenosine released from ATP breakfdown
- Bradykinin released from ischemic tissue
- activates cardiac C fibers in T1-T5 spinal pathway
What 12 lead EKG changes might be seen in someone with an AMI? (3)
- ST depression
- ST elevation
- T-wave inversion
What diagnostics are used to assess for coronary artery disease? (5)
- 12 lead EKG
- Exercise stress test
- Nuclear stress test
- Echocardiography
- Angiography
Compare exercise and nuclear stress test
- EST: Patient walks on a treadmill or pedals a bike, relies on EKG changes
- NST: Combines stress (exercise or drug like adenosine) with a radioactive tracer injection
Why is nuclear stress test preferred?
- Greater sensitivity
- asses coronary perfusion vs ischemic areas
- Size of perfusion abnormality = significance of CAD detected
- Estimates LV systolic size and function
- Differentiates new perfusion abnormality vs. “old” MI
How does the tracer identify ischemic areas?
Poor tracer uptake pinpoints ischemic or scarred areas
Areas of persistently absent uptake signify an old MI
For nuclear stress testing, what is the most important indicator of CAD?
- The size of the perfusion abnormality
- bigger size = more CAD
What nuclear stress test tracers are used with exercise?
Thallium
What nuclear stress test drugs are used without exercise?
- Atropine, Dobutamine, Pacing (increases HR)
- adenosine, dipyridamole (coronary dilator)
When are adenosine and dipyridamole used with nuclear stress testing? Why?
- For patients who cannot undergo normal stress testing
- They dilate normal coronary arteries but not atherosclerotic ones (shows as abnormality in reading)
What test would be useful for imaging wall motion abnormalities or valvular function?
Echocardiography
What is coronary angiography? What is it useful for?
- Determines location of occlusive disease
- diagnose prinzmetal angina
- assess results of angioplasty/stenting
Does coronary angiography measure plaque stability? (i.e. is it going to dislodge?)
Does not measure plaque stability in CAD
What is the mechanism of action for aspirin? Recommended dose?
- COX-1 enzyme Inhibition
- TXA2 inhibition (prostaglandin)
- Permanent Plt aggregation inhibition (7-10 days)
- 75-325mg/day
How can aspirin be reversed?
Trick question. It can’t be, platelets are damaged until they die and are replaced. (7-14 days)
- What are Platelet glycoprotein IIb/IIIa receptor antagonists? What do they do?
- abciximab, eptifibatide, tirofiban
- Inhibit platelet activation, adhesion, and aggregation.
How do P2Y12 inhibitors work? What drugs were discussed in class?
Inhibit ADP receptor P2Y12 and thus inhibit platelet aggregation
* Clopidogrel
* Prasugrel (Effient)
How do PPIs affect P2Y12 inhibitors?
- PPIs inhibit CYP450 which activates prodrug clopidogrel (P2Y12 inhibitor)
- results in reduced drug efficacy = increased clotting
How does Prasugrel compare to Clopidogrel?
- More predictable pharmacokinetics
- greater bleeding risk
What drug classes are synergistic with nitrates? (2)
beta-blockers
calcium channel blockers
What are benefits of nitrates?
- Increase amount of exercise to produce ST-segment depression
- Dilate coronary arteries and collaterals
- Decrease PVR
- Decreases preload
- Potential anti-thrombotic effects
When are nitrates contraindicated? (2)
- Aortic Stenosis
- Hypertrophic Cardiomyopathy
- Decreased preload and afterload = hypotension
What drug class is the only one proven to prolong life in CAD patients?
beta-blockers
What properties do β-blockers have?
- Anti-ischemic
- Anti-hypertensive
- Anti-dysrhythmic
Which β blockers are cardioselective? (beta 1)
- Atenolol
- Metoprolol
- Acebutolol
- Bisoprolol
Which β blockers are non-selective? (beta 1 & 2)
- Propanolol
- Nadolol
What risk is associated with non-selective β blockers in asthma patients?
↑ risk of bronchospasm in reactive airway disease patients.
What drug class decreases severity/frequency of coronary vasospasm?
Calcium Channel Blockers
What are ACE inhibitors used for?
- Hypertension
- Heart failure
- Cardioprotective
Angiotensin II causes an increase in what 4 things?
- Myocardial hypertrophy
- Interstitial myocardial fibrosis
- Coronary vasoconstriction
- Inflammatory responses
What are statins used for?
Coronary plaque stabilization
Reduces mortality noncardiac surgery and vascular surgery
Decreases:
* Lipid oxidation
* Inflammation
* Matrix metalloproteinase
* Cell death
When is revascularization indicated?
- Failure of medical therapy
- > 50% L main coronary artery
- > 70% epicardial coronary artery
- Impaired EF < 40%
When is CABG indicated?
- LMCA involvement, 3-vessel disease, DM + 2 or 3-vessel disease
- Failed PCI/angioplasty
- ventricular septal rupture
- mitral regurgitation
What is ACS? What are the 3 categories of ACS?
Acute or worsening imbalance of myocardial oxygen supply to demand
1. Unstable angina
2. NSTEMI
3. STEMI
What is the major cause of STEMI: emboli or thrombosis?
Thrombosis is major cause
Rarely emboli
Diagnostic data of STEMI?
-
eleveated troponin (must have) and at least one of the following:
ischemia symptoms
ST-T changes/new LBBB
pathological Q-waves on EKG
imaging/angiography of thrombus
what is the most specific diagnostic lab for an MI?
Troponin
How soon will troponin start to increase after myocardial injury? How long might they remain elevated?
- 3 hours after MI
- 7-10 days
What drugs are used for reperfusion therapy?
What is the time frame?
- tPA, streptokinase, reteplase, tenecteplase
- initiate within 30-60 mins
- < 12 hrs from onset
How soon should PCI occur after an ischemic event?
Within 90 minutes of hospital arrival
Within 12 hours of symptom onset.
How soon should initiation of tPa be for ischemic event?
Within 30-60 min of hospital arrival
Within 12 hours of symptom onset.
What are indications for PCI treatment of an MI?
- Contraindicated tPa therapy
- Severe HF and/or pulm edema
- S/S for 2-3 hours
- Mature clot
What risks are associated with PCI (percutaneous coronary intervention)?
- Bleeding
- Thrombosis
- endothelium destruction
What are the goals of care for unstable angina/NSTEMI?
- decreasing myocardial oxygen demand
- stabilizing culprit lesion
- prevention of disease progression
What is the treatment for unstable angina/NSTEMI?
- MONA
- DAPT and/or heparin
- calcium channel blockers, beta blockers
- analgesics
- tPA not indicated
What is Dual Antiplatelet Therapy (DAPT)?
ASA + P2Y12 inhibitor
How long would one want to wait for elective surgery post angioplasty without stenting?
2 - 4 weeks
How long would one want to wait for elective surgery post angioplasty with bare-metal stent placement?
30 days - 12 weeks
How long would one want to wait for elective surgery post angioplasty with drug-eluting stent placement?
1 year
How long would one want to wait for elective surgery post-CABG?
6 weeks - 12 weeks
When can we D/C clopidogrel/ticagrelor or prasugrel before surgery? ASA?
- clopidogrel/ticagrelor = 5 days
- prasugrel = 7 days
- ASA = continue
In these ACS pts, what is the preferred drug for bradycardia?
Glycopyrrolate or atropine can be used
glycopyrrolate > atropine (less chronotropic/central effect)
What ACS drugs must be continued perioperatively?
Beta blockers
What antihypertensive drugs can be stopped 24 hrs before surgery?
ACE inhibitors
What is the goal for glucose in ACS patients?
< 180 mg/dL
What can cause decreased O2 delivery and/or increased O2 demand in periop?
- bleeding
- inflammation
- pain
- shivering
- hypoxia
- hypotension
What components are worth 1 point on the Revised Cardiac Risk Index (6)?
- High risk surgery
- IHD
- Hx of CHF
- Hx of CVA
- DM on insulin
- Cr > 2 mg/dL
What % risk of major cardiac events would be conferred by a RCRI score of 0, 1, 2, or >3?
- 0 = 0.4%
- 1 = 1.0%
- 2 = 2.4%
- > 3 = 5.4%
- 0-1 = low risk, > 1 = elevated risk
What does 1 MET equal?
3.5mL O₂/kg/min
What are the 3 surgical urgency criteria?
Emergency: within 6 hr
Urgent: within 6-24 hr
Time-sensitive: within 1-6 weeks
What kind of cardiac criteria would you avoid anesthesia?
- Recent MI (>60 days post MI ideal)
- unstable/severe angina
- Decompensated HF
- Severe valvular disease
- significant dysrhythmias
- age
What drug is the preferred treatment for tachycardia?
Esmolol
Drug of choice for hypotension?
- fluid bolus
- ephedrine, phenylephrine
What does the RCA supply?
- posterior/inferior LV
- Posterior fascicle of LBB
- Pacemakers (SA/AV)
- Right ventricle
What does the LAD supply?
- septum
- Anterior wall LV
- Bundle branches
What does the circumflex supply?
- posterior/lateral LV
- Pacemakers (SA/AV)
What coronary artery would you expect to be affected from abnormalities noted on II, III, and aVF?
- “I” = inferior MI
- RCA
What coronary artery would you expect to be affected from abnormalities noted on I and aVL?
- “L” = lateral
- Circumflex
What coronary artery would you expect to be affected from abnormalities noted on V3 - V5?
- A + L = anterolateral LV
- LAD
What are some contraindications for tPa?
- Major surgery
- uncontrolled HTN
- aneurysms
- recent thrombolytics
- active bleeding
Raking leaves, gardening would be what MET equivalent?
4 METs
Climbing 1 flight of stairs, dancing or bicycling would be what MET equivalent?
5 METs
What drug class is indicated in patients with severe LV dysfunction?
Opioids > general anesthesia
Is nitrous oxide contraindicated in MI patients?
N2O does not inrease mortality and CV complications
What are the 2 contradictory implications of volatile anesthetics in MI patients?
- Decreases myocardial O2 requirements
- Decreases BP and coronary perfusion pressure
What is pseudonormalization of T waves?
When a pt has chronically inverted T waves from previous MI/ischemia and now are upright and “normal” during myocardial ischemia
