ISCHEMIC HEART DISEASE Flashcards
1
Q
risk factors for development of CAD
A
**male gender
**increasing age
hypercholesterolemia
HTN
cigarette smoking
DM
obesity
sedentary lifestyle
family hx
personality (stress, type A)
2
Q
stable angina
A
partial occlusion or chronic narrowing of a segment of coronary artery
- no change in frequency, severity, or duration x2months
- occurs in a predictable pattern, predictably relieved
3
Q
angina pectoris
A
imbalance between myocardial oxygen supply & demand
- release of adenosine & bradykinin = pain, slowing of AV conduction rate, decreased contractility
4
Q
unstable angina
A
- angina at rest
- angina of new onset
- increase in severity or frequency of previously stable angina
5
Q
major treatment categories of CAD
A
- lifestyle modification
- pharmacologic therapy
- revascularization
6
Q
pharmacologic therapy for CAD
A
- antiplatelet drugs (aspirin 81mg, plavix/ticlid if indicated)
- BB (decrease O2 demand via decreased HR & contractility, increased supply via increased coronary perfusion time)
- CCB (long acting); uniquely effective in variant angina
- nitrates (dilate coronaries & collaterals –> increased supply)
- ACEI/ARBs
7
Q
ACS pathophysiology
A
hypercoaguable state: - focal disruption of plaque susceptible plaques = fibrous cap + lipid-rich core - triggers coagulation cascade: -- thombus formation -- vasoconstriction
8
Q
diagnosis of acute MI
A
2 of:
- chest pain
- serial EKG changes indicative of MI
- increase & decrease of serum cardiac enzymes
9
Q
MI treatment
A
- evaluate hemodynamic stability/tx if necessary
- 12 lead EKG
- administer O2
- pain relief: IV morphine (reduce catechol)
- nitroglycerin (dilate)
- aspirin/plavix (decrease further thrombus formation)
- reperfusion therapy (tPA, streptokinase) w/in 30-60mins of arrival (RISK: ICH)
- coronary angioplasty (preferred to reperfusion) w/in 90mins of arrival
10
Q
acute MI complications
A
- cardiac dysrhythmias (including vfib, vtach, afib, HB)
- pericarditis (px worse w/ inspiration & lying down; auscultate friction rub)
- mitral regurg (ischemia of papillary m. or vent m. @ attachment point) –> papillary m. rupture?
- ventricular septal rupture
- CHF & cardiogenic shock (hypotension/oliguria)
- myocardial rupture
- RV infarction (isolated RV infarct is unusual)
- CVA
11
Q
preoperative MI factors that change incidence
A
- preoperative medical condition
- specific surgical procedure
- surgeon skill
12
Q
surgery-induced risk factors of MI
A
- inflammatory response = hypercoaguable state (lead to decreased O2 supply)
- neuroendocrine response = increased HR/BP (increased O2 demand)
- postop shivering = increased O2 demand
- decreased Hct = decreased O2 supply
- hypoxia = decreased O2 supply
13
Q
major clinical predicators of increased perioperative CV risk
A
- unstable coronary syndromes (acute/recent MI, unstable or severe angina)
- decompensated HF
- significant dysrhythmias (AVB, symptomatic ventricular dysrhythmias, supraventricular dysrhythmias w/ rapid ventricular rate)
- severe valvular heart dz
14
Q
intermediate clinical predictors of increased perioperative CV rsik
A
- mild angina
- h/o MI
- compensated or h/o HF
- DM
- renal insufficiency
15
Q
minor clinical predictors of increased perioperative CV risk
A
- advanced age (>70)
- abnormal EKG (LV hypertrophy, LBBB, ST abnormalities)
- rhythm other than SR
- low functional capacity
- h/o CVA
- uncontrolled HTN
16
Q
best evidence of decreased cardiac reserve (in the absence of significant lung disease)
A
exercise tolerance
- if pt can climb 2-3 flights of stairs w/out symptoms, it is likely that cardiac reserve is adequate
17
Q
elective surgery after angioplasty?
A
- wait 4-6 weeks
- 6 weeks after bare metal stent placement
- 12 months after drug-eluting stent placement
18
Q
high risk surgery
A
- emergency major surgery
- AAA repair or other major vascular surgery
- peripheral vascular operation
- prolonged procedures w/ large fluid shifts/blood loss:
- thoracotomy
- major abdominal operation
19
Q
preoperative management goals w/ ischemic heart disease patient
A
- determining the extent of ischemic heart disease & any previous interventions
- determining severity & stability of the disease
- reviewing medical therapy & noting any drugs that can increase bleeding/contraindicate a particular anesthetic technique
20
Q
Lee Revised Cardiac Risk Index
PREOP
(6 independent predictors of major cardiac complications)
A
- high risk surgery
- ischemic heart disease
- CHF
- cerebrovascular disease
- IDDM
- creatinine >2.0mg/dL
21
Q
preop algorithm for pts with ischemic heart disease
A
- emergent/urgent surgery?
- optimize & proceed - elective surgery?
- unstable CAD/change in cardiac condition –> get cardiac consult
- stable –> stratify risk further:
risk stratification:
for high/intermiedate risk procedure w/ moderate/minor risk factors:
1. prior revascularization?
- prior CABG w/ stable medical condition = proceed to OR
- prior PCI = consider type of stent & proceed accordingly
2. no prior revascularization?
- stable CAD = proceed to OR
- unstable or unable to assess = obtain noninvasive testing FIRST
22
Q
functional capacity evaluation & documentation
A
expressed as metabolic equivalent of task (MET)
- 3.5mL/kg O2 consumption = 1 MET
- increased risk w/ poor functional capacity, <4MET
4MET = baking, dancing, golfing, walking
23
Q
intermediate risk surgery
A
- carotid endarterectomy
- head/neck surgery
- orthopedic surgery
- prostate surgery
- intraperitoneal & intrathoracic surgery
24
Q
low risk surgery
A
- endoscopic
- superficial
- cataract
- breast
25
who gets further cardiac evaluation preoperatively?
2 of:
1. high risk surgery
2. low exercise tolerance
3. moderate clinical risk factors
26
interventions that can modulate triggers of perioperative cardiac events
1. statins = decrease plaque buildup
2. antiplatelet/angicoagulants = decrease thrombus formation
3. oxygen = decrease hypoxia
4. transfusion = increase hct/O2 delivery
5. nitroglycerin = prevent vasoconstriction
6. maintain BP = ensure adequate coronary flow
7. alpha2 agonists/analgesics = attenuate neuroendocrine response to surgery (catechol release)
8. normothermia = prevent shivering (O2 demand)
9. BB = prevent increased O2 demand
27
intraoperative management goals in those w/ ischemic heart disease
1. optimize myocardial O2 supply & keep O2 demand low
| 2. monitor for ischemia, & tx it if it develops
28
factors that decrease myocardial O2 supply
1. decreased coronary blood flow (patency)
2. tachycardia
3. diastolic hypotension
4. hypocapnia (= coronary artery vasoconstriction)
5. coronary artery spasm
6. decreased PaO2
7. anemia
8. arterial hypoxemia
9. L shift of oxyhemoglobin dissociation curve
10. increased blood viscosity
29
factors that increase myocardial O2 demand
1. SNS stimulation
2. tachycardia
3. HTN
4. increased myocardial contractility
5. increased afterload
6. increased preload
7. shivering
8. hyperglycemia
30
induction of anesthesia in pts w/ ischemic heart disease
1. anxiolysis pre-operatively
2. no ketamine, preferably etomidate or high opioids
3. use NDNMB w/out HR/BP implications (vec, roc, cis)
4. be quick w/ DL
5. minimize SNS response = lidocaine, esmolol, fentanyl
31
anesthesia maintenance w/ ischemic heart disease
- AVOID TACHYCARDIA
- NO HYPOTENSION
- keep vitals w/in 20% of pre-op value
- normal preload & afterload
- decrease contractility if LVF is normal (demand)
- maintain NSR
Options
- volatile agent = controlled myocardial depression to avoid increased demand
- opioids for those w/ LVF = avoid myocardial depression w/ volatiles
- regional = avoid hypotension >20% of initial BP --> phenylephrine or ephedrine if bradycaria
32
EKG monitoring for ischemia perioperatively
- evaluate for ST depression
- II (RCA)
- V5 (LAD)
33
lead/vessel relationship
```
RCA = II, III, aVF
LCx = I, aVL
LAD = V3, V4, V5
```
34
perioperative ischemia monitoring options
1. EKG (ALWAYS)
2. PA cath (not shown to be associated w/ improved outcomes)
3. transesophageal echocardiography (evaluate regional wall motions)
- abnormalities occur before EKG changes occur
- abnormalities can be attributed to events other than myocardial ischemia
35
intraoperative management of MI
- when ST segment changes >1mm on EKG
tx changes in HR/BP
- IV BB
- nitroglycerin if BP elevated
- sympathomimetic to tx hypotension
- inotropes if hemodynamically unstable
- intra-aortic balloon pump may be necessary
- plan for early postop cardiac catheterization if applicable
36
causes of ischemic heart disease
- atherosclerosis (most common)
- severe HTN or tachycardia
- coronary artery vasospasm
- hypoxia
- anemia
- severe AI or AS
37
perioperative MI incidence
risk of perioperative death 2/2 cardiac causes = <1% in general population
- most perioperative MIs occur w/in the first 24-48hrs postoperatively
