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Flashcards in CAD reduced Deck (24):
1

Most perioperative MIs occur within ____________. what are the typical diagnosis patterns

24- 48hours

Typical diagnosis patterns not on slides!

  1. Mostly postoperative
  2. Mostly N-STEMI and diagnosed with EKG and cardiac biomarkers 
  3. they are usually preceeded by tachycardia and ST depression
    • tachycardia increases Oconsumption→ with CAD  the coronaries inability to dialate leads to the MI

2

What physiologic changes post-op that lead to a pro-thrombotic state and plaque rupture

(NOT IN LECTURE)

  1. increased blood viscosity
  2. ∆s in catecholamine levels
  3. ∆s in cortisol levels
  4. ∆s in endogenous tissue plasminogen activator levels
  5. ∆s in plasminogen activator inhibitor levels.

(post op autopsies have shown significant numbers of deths via trhombus in a coronary artery that is NOT critically stenosed→even MORE reason to make sure to blunt the stress response!)

3

Main problem in ischemic heart disease

Imbalance between myocardial O2 supply and  demand

4

Compare Stable, Unstable and Prinmental Angina

Stable:

  • no ∆ in frequency or duration in the last 60 days
  • associated with a fixed narrowing (usually 75%+)
  • relieved by rest or NTG 

Unstable:

  • becoming more frequent, longer, or more severe
  • occuring at rest or with less exertion;
  • associated with an unstable plaque/thrombosis;
  • signals impending MI

Prinzmetal: coronary vasospastic disease

 

5

What are the casues of ischemic heart disease?

Caused by increased oxygen demand or decreased oxygen supply

  1. Athlerosclerosis is the mose common casue
  2. Severe Hypertension or tachycardia
  3. Coronary Vasospasm
  4. Severe Hypotension
  5. Hypoxemia
  6. Anemia
  7. Severe aortic insuficiency or Aortic Stenosis

6

What are the Clinical manifestations of ischemic heart disease?

  1. Angina
  2. Ischemia
  3. Myocardial Infarction
  4. Arrythmias
  5. Ventricualr dysfunction 
  6. Congestive heart failure
  7. Sudden death

7

Ischemic heart disease drug management and effects: 

  1. ß-Blockers-
    • decreases HR and contractility 
  2. Ca++ Channel Blockers
    • dilates coronaries, decreases contractility, decreases afterload
  3. ACE inhibitors
    • improve contractility via decreased afterload
  4. Nitrates
    • dilates coronaries and collaterals, decreases preload (vasodilation) and afterload (decreases periperal vascular resistance) 
  5. Antiplatelets-
    • reduce potential for thrombosis

8

Ischemic heart disease surgical interventions

 

  1. PCI- balloons, stents, drug stents
  2. CABG- off-pump, minimally invasive, robotics, all kinds of stuff
  3. Transmyocardial revascularization- sounds impressive

9

What is myocardial Infarction?

  1. Necrosis caused by ischemia
  2. In the heart, begins to occur within 20-30 minutes of ischemia onset
  3. Typically starts in the subendocardium
  4. Full infarct size usually occurs in 3-6 hours
  5. Size depends on proximity of lesion and collateral circulation

10

Periop MI risk

  • Risk is less than 1% in the general population
  • Most occur in the 24-48 hours after surgery

11

What  decreases Myocardial O2 SUPPLY and should be avoided/prevented/promtly treated in patients with CAD?

  1.  **Tachycardia** (sympathetic stimulation)
  2. Hypotension (decreases coronary blood fow) 
  3. Vasoconstriction
  4. disruptions in O2 carrying capacity
    1. acid/base (hypocapnea from hyperventilation will also cause coronary vasoconstiction)
    2. anemia
    3. hypoxia 
  5. Blood Viscosity
  6. Arterial patency
  7. Coronary spasm

12

What increases myocardial O2 DEMAND and should be avoided/prevented/promtly treated in patients with CAD?

  1. **Tachycardia**
  2. Increased contractility (drugs)
  3. Increased preload (fluids)
  4. Increased afterload (drugs)
  5. Shivering
  6. Hyperglycemia
  7. HTN

13

regoional vs general anesthesia in patients with Ischemic heart disease/CAD 

  1. Regional
    • sympathectomy will likely lead to hypotension
    • treat with phenylephrine.
    • Use ephedrine if bradycardia also present.
  2. General  
    • Maintain O2 supply/demand balance
    • DO NOT allow for sustained periods of hypo/hypertension or tachycardia.

14

Monitoring for ischemia with an EKG

  • EKG indicators of ischemia?
  • what can individual leads tell us?
  • What leads are best?

  1. EKG - Ischemia is manifested by
    • ST elevation or depression (+/- 1 mm MUST be detected)
    • T-wave changes (may have inverted T waves from an old MI and ischemia a is manifested as T waves that are right-side-up)
    • R-wave changes
  2. Leads II, III and aVF reflect: Right coronary artery
    • ​​supplies:
      • Right atrium and right ventricle
      • Inferior aspect of left ventricle
      • SA node and AV node
  3. Leads V3-V5 reflect: Left anterior descening 
    • supplies:  Anterolateral aspect of left ventricle
  4. Leads I and aVL reflect: Left circumflex artery
    • supplies:  Lateral aspect of left ventricle
  5. ​​​​​​Best lead combos (II and aV5) or (II, V4, V5) or (V3, V4, V5)

(Slide says we can also use TEE and PA catheters)

15

Ischemic heart disease Induction anesthesia considerations

The goal is to minimixe hemodynamic changes

  1. Decrease the duration of laryngoscopy
  2. Minimize SNS response
    • USE: gas, lidocaine, Propofol, opioids esmolol
    • Ketamine is definately a NO!!
  3. For severe LV dysfunction
    • May not tolerate anesthesia induced myocardial depression  
    • USE: high opioid technique and  Etomidate!

16

Ischemic heart disease anesthetic mainitinence GOALS

  1. **Avoid tachycardia** and keep in a NSR
  2. Normal Preload
  3. Normal Afterload 
  4. Decrease Contractility (if LVF normal)
  5. MVO2 - much easier to control demand, attenuate SNS outflow

​(NOT ON powerpoint)

  1. **Avoid tachycardia** and keep in a NSR
    • pretreat for anything that will elicit a sympathetic resopnse (DVL, incision)
    • ß-blocker - esmolol
    • Opioids
  2. Normal Preload
    • do not want to rapidly increase preload, it will increases myocardial demand - steeady smooth fluid balance (consider phenylephrine or dobutamine)
  3. Normal Afterload 
    • ​​too low = decreased coronary profusion pressure (decreases supply)
    • too high = myocardial contractility must increase to overcome (increases demand) (vasodilate IAs or NTG)
  4. Decrease Contractility (if LVF normal)
    • this will decrease the myocardial O2 demand
    • ß-blockers
    • Gas
  5. Maintain NSR if possible
  6. MVO2 - much easier to control demand, attenuate SNS outflow as needed (avoid sympathomimetics)

17

major

clinical predictors of increased periop cardiovascular risk

may require delay of elective surgery to get cardiology evaluation

  1. unstable coronary syndrome
  2. acute/recent MI
  3. unstable/severe angina
  4. decompensated heart failure
  5. significan dysrhythmia
  6. high grade AV block
  7. sympromatic ventricular dysrhythmia with underlyining heart disease
  8. SVT with uncontrolled rate
  9. severe valvular disease

18

minor 

clinical predictors of increased periop cardiovascular risk

markers of coronary disease not demonstrated to increase peri-op risk

  1. advanced age (>70yo)
  2. abnormal EKG (left ventr hyperthrophy, LBBB, etc)
  3. rhythm other than sinus
  4. low fxn capacity
  5. hx of stroke
  6. uncontrolled HTN

19

who gets further testing before going into OR

  1. pts with two of these factors:
    1. high risk surgery
    2. low exercse tolerance
    3. moderate clinical factors
  2. pts with low funtional capacity
  3. pts whose functional capacity cannot be assessed

20

high risk surgeries

  • abdominal aortic aneurysm (AAA)
  • aortic or major vascular surgery
  • peripheral vascular surgery
  • thoracotomy
  • major abdominal surgery
  • prolonged surgery with large fluid shift

21

intermediate risk surgery

carotid edarterectomy

head & neck surgery

intraperitoneal and thoracic surgery 

ortho

prostate

22

low risk surgery

endoscopic surgery

superficial surgery

cataract surgery

breast surgery

23

who can go to surgery without need of stress testing

  • no prior revascularization but stable CAD & good exercise tolerance
  • unstable CAD/low exercise tolerance BUT EKG and non invasive testing came negative 
  • unstable CAD/low exercise tolerance BUT the cardiac cath showed no left main disease 
  • had CABG (
  • PCI with bare-metal stent in > 6 weeks, minila anti-platelet & no change in medical condition

24

who needs cardiac consult before surgery

  • PCI in the last 12 months with DES and dual antiplatelet therapy
  • unstable CAD or decreased exercise tolerance w/ positive EKG and left main artery disease on cardiac cath