Case 2 - Recent MI

Question 1

Patient comes to your pre-op clinic for evaluation and clearance prior to surgery. How would you assess the cardiac history?

Answer 1

1) severity and reversibility of CAD
* RF, anginal patterns, history of MI
2) LV and RV function
* excercise capacity, pulm edema, pulm HTN
3) presence of sympatomic arrhythmias
* palpitations, syncopal or presyncopal episodes

4) coexisting valvular disease

5) presence of PPM or ICD

Question 2

What is considered 4 METs, what is considered less than 4 METs

Answer 2

METs 1 to 3:

• eat, dress, use toilet
• walk indoors around house
• walk a block or 2 on level ground

METs of 4 or greater:

• do light work around house (washing dishes)
• climb a flihgt of stairs or walk up a hill
• run a short distance

Question 3

What are active Cardiac condtions that require noninvasive testing?

Answer 3

Active Cardiac Conditions / Major Clinical Risk Factor

• Unstable coronary syndromes
  
  • unstable angina
  • Recent MI (w/i 7-30 days -> high rate of reinfarct)
• decompesated CHF
• Significant arrhythmias
  
  • 3rd degree AVB, mobitz type 2
  • symptomatic ventric arrhythmias
  • SVT with RVR (> 100 bpm)
  • symptomatic bradycardia
• Severe valvular disease
  
  • Severe AS
    
    • mean pressure gradient > 40 mm Hg
    • AVA < 1.0
    • symptomatic - angina, DOE, syncope
  • severe MS
    
    • symptomatic (DOE, exertinal presyncope, CHF)

Question 4

What are considered high risk surgeries? What makes them high risk surgeries?

Answer 4

high risk surgery

• procedures with greater potential for hemodynamic cardiac stress
  
  • alterations HR, BP fluctuation, fluid volume shifts, clotting issues, oxygenation issues, neurohumoral activation, blood loss, pain
  • all factors lead to increase in periop cardiac events (PCE)
• aortic and other major vascular surgery
• peripheral vascular surgery

Question 5

Review the algorithm for managing a patient with CAD underoing noncardiac surgery

Answer 5

clinical risk factors:

revised cardiac risk index

• ischemic heart disease
• CHF
• DM (insulin dependent)
• CVA
• SCr > 2

Question 6

You go through algorithm and decided to order a noninvasive cardiac test (like dobut stress echo), it shows reversible drug induced ischemia. Which patients should be considered for coronary revascularilzation before noncardiac surgery?

Answer 6

Coronary revascularization:

• includes percu coronary angioplastic, stent, and CABG

coronary revasc before noncardiac surgery:

• stable angina with left main coronary stenosis
• stable angina with 3-V disease
• stable angina with 2-V disease + significant proximal LAD stenosis and EF < 50% or ischemia on noninvasive testing
• STEMI
• unstable angina or NSTEMI

Question 7

what are the recommendations for stent/PCA and noncardiac surgery?

Answer 7

patients should remain on dual antiplatelet therapy prior to elective surgery for…

PCA - wait > 4 weeks

BMS - wait > 6 weeks

DSE - wait > 12 months

**CABG - no specific recommendation. **

• resonable to wait 4-6 weeks with CABG

continue ASA in all cases during perioperative period

Question 8

patient has a recent DES placed (2 months ago), and he comes for emergent surgery. Should his dual anti plt therapy be continued during periop period?

Answer 8

• dual antiplatelet therapy should be continued in periop period if possible
• if not, then continue ASA and restart thienopyridine (plavix) ASAP
• ALWAYS asses risk vs benefit: does decrease in surgical bleeding outweigh risk of stent thrombosis

Question 9

What intraop monitors would you use in a recent MI patient presenting for emergent surgery?

Answer 9

1) Arterial line

• beat to beat blood pressure monitoring
• maintain BP within 20% of preop values
• facilitate lab testing: glucose, acid-baes status, h/h
  
  • hyperglycemia independent risk factor of periop cardiac event

2) temperature

• normothermia. hypothermia inc o2 demand

3) EKG

• multilead EKG. Lead II and V5 - detects >90% ischemic episode
• ST segment continuous analysis
• not useful in LVH, LBBB, Ventric PPM, conduction abnormalities

4) PAC

• V waves on PCWP is an indication of myocardial ischemia (not reliable)
• intravascular volume status
• SVo2
• calculate PVR, SR, SV

5) TEE

• most sensitive detector of intraop ischemia
• RWMA
• LVEF, intravasc status, LV/RV function

Question 10

patient is having ischemia and hemodynamic aberrations intraop, what will you do treat?

Answer 10

myocardial supply and demand imbalance

• goal: increase supply, decrease demand
• Decrease demand
  
  • dec HR - BB
  • dec contractility - BB
  • decrease afterload - BB and NTG
  • decreaes preload - nitroglycerin
• increase supply
  
  • SaO2 increase
  • h/h
  • increase aortic diastolic pressure - phenylephrine

Question 11

what are your anesthetic managemnet goals in a patient with recent MI, presenting for surgery?

Answer 11

no anesthetic technique proven to be superior

Goals: maintain o2 supply and demand balance

• avoid tachycardia (ketamine, panc)
  
  • opioid for pain control
• avoid inc afterload
• avoid inc preload
  
  • judicious fluid use. use vasopressor for hypotension
• avoid inc contracility
  
  • use inhaled anes / IV anesthetic - dec myocardial contracility, venodilator and dec SVR

Question 12

how would you manage this patient who underwent emregent surgery with a recent MI postoperatively?

Answer 12

• ICU for continous monitoring
  
  • hemodynamic alterations, hypothermia, ischemia)
• **Most common time for periop cardiac events is w/i 48 hrs of surgery**
• serial troponin measurement with chest pain or EKG changes
• proper pain managment to avoid excess sympathetic stimulation -> inc o2 demand