Cardiac patient peri-operative period Flashcards
What is the purpose of preoperative evaluation in cardiac patients?
- ensure adherence to guideline directed medical therapy (GDMT)
- provide clinical risk profile for informed decision making
- cardiac complications are a leading cause of morbid/mortality (17%)
What is the definition of myocardial infarction?
- Rise and or fall in serum troponin plus:
- Evidence of ischaemia based on
- ECG - new changes (path q waves)
- imaging evidence of new loss of myocardium/regional wall abnormality
- angiographic criteria (coronary thrombus on angio/autopsy)
What is MINS? Why is it significant?
Myocardial injury after non-cardiac surgery
- only relevant 30 days post
- VISION 2012 - vascular events in non cardiac surgery - showed peak trop t (TnT) associated with 30 day mortality. Used 4th gen (not high sensitivity trop) with measures in 3 post op days
- VISION 2017 used fifth gen trop - a change in 5ng/L was associated with mortality - severity of MINS (hs-TNT rise) correlated with 30 day postop mortality
updated criteria
- elevated postop hs-TNT
- resulting from myocardial ischaemia (no evidence of non-ischaemic aetiology)
- e.g. sepsis
93% with MINS have no ischaemic sxs
What is the severity scale for MINS? what are some stats surrounding how common it is?
MINS 12-18% of patients over 45 years and
patients undergoing vascular surgery with risk factors are 17% of MI
30 day mortality <20ng/L = 0.5% 20-64ng/L = 3% 65-999ng/L = 9.1% >1000ng/L = 29.6%
What is the risk of perioperative stroke?
risk = 0.08-2.9% after general surgery - covert stroke is higher.
Overt stroke has poor prognosis (death in 16-18%)
NeuroVISION - age 65 or older 7% risk of covert stroke.
- cerebral emboli on MRI in 13%
- 1/4 of patients had prior chronic infarct on postop MRI
What are the classifications of MI?
Type 1 MI
- due to plaque rupture and subsequent intraluminal thrombus
- ST elevation
Type 2 MI
- due to supply/demand mismatch
- coronary flow does not meet demand (periop stress)
- ECG changes minor
Most periop MIs are ‘silent’/aymptomatic (65-68%)
What are some risk factors for a type 2 MI?
Anything causing supply/demand mismatch: Poor supply - tachycardia - arrhythmias - CAD - hypertrophic cardiomyopathy - aortic stenosis Increased demand - sympathetic stimulation - shivering
What are some factors that may contribute to periop trop rise?
postoperative troponin rises may be
1) myocardial ischaemia
- type 1 (MI - plaque rupture/thrombus)
- type 2 (increased demand)
2) non-ischaemic cardiac causes
- cardiac failure
- cardiac trauma (pacing)
- stress cardiomyopathy
- myocarditis
3) non cardiac disease
- PE
- sepsis
- neurologic (stroke)
4) Drug induced
- chemotherapy (antracyclines - adramycin/doxorubicin, bevacizumab)
5) chronic pre-existing troponin elevation
- cardiac failure
- CKD
What are some challenges in cardiac risk stratification for non-cardiac surgery?
Multiple guidelines - ACC (US), ESC (European), CCS (Canadian)
what strategy?
- disability, death, mortality
What is the RCRI used in the Canadian risk stratification system?
RCRI gives equal weight to
- high risk surgery (intraperitoneal, intrathoracic, suprainguinal vascular)
- IHD
- CCF
- cerebrovascular disease
- insulin dependent diabetes
- renal impairment
they combine this with proBNP to stratify necessity for the procedure and risk.
What is MACE? What are some considerations in perioperative cardiac care?
MACE - major adverse cardiac event
surgical risk
- low
- intermediate
- high risk
patient specific risk
- 3 major risk indexes
What is the NSQIP MICA risk index used by Americans?
MICA may underestimate risk because biomarker surveillance not performed
- but outperformed RCRI in vasc surgery
NSQIP
- 21 patient specific variables
- neither has external validation
Should we use cardiac biomarkers when assessing cardiac risk?
Natriuretic peptides
- BNP (brain natriuretic peptide) >92
- N-terminal pro BNP (NT-proBNP) >300
produced by myocytes in response to wall stress and ischaemia
- CCS recommends measurement if baseline risk >5%
Troponin
- Cardiac troponins (T and I) are preferred for diagnosis
What are some other risk prediction tools for cardiac risk?
P -POSSUM - only post-op, in research, over-predicts in young and under- predicts in elderly
RCRI
MACE - (MI, APO, VF, cardiac arrest, CHB)
- under-predicted in vascular patients
NSQIP
- surg risk calculator
- data about co-morbidities and operation
- nice presentation and for shared care, nil external validation
AHA prior testing pre-op
- risk via RCRI + combining it with assessment of functional capacity
European guideline
- <4 METS
- ECHO or stress depending on risk factors
How can you assess exercise tolerance/pre-op risk? what are some tools?
MET (metabolic equivalent)
- O2 sitting at rest in 40y.o. male 14mlO2/kg/min
- one flight of stairs (2 flights or 4 mets)
less than VO2 max 15 of 4 METS = high risk
1) physician and self assessment are poor predictors
2) DASI - questionaire structured
0-58 and use a formula for approximation
- only moderate
3) Troponin/BNP pre-op
- associated with increased rate of Cx
- variable thresholds used
Why might you choose to undergo perioperative cardiac testing? What are some options
- elevated risk
- Unknown functional capacity (METS <4)
testing must improve decision making and guide management
Tests:
- 6 minute walk test
- number of laps
- cardiopul transplant planning
- discriminate high/low risk well - Exercise testing (CPET)
- VO2 max/anaerobic threshold (bike/treadmill with protocol)
- ECG monitoring
- BNP vs CPET 2013 showed good prediction
METS study coming soon (subjective vs CPET vs DASI vs BNP)
What are some risk factors that predict perioperative risk in cardiac patients?
CAD
HF
- JVP, creps, thirs heart sound
- HFREF, HFPEF
cardiomyopathy
- restrictive vs dilated
- HOCM - tachycardia, vasodilation, volume loss and reduced preload worsen dynamic left ventricular outflow tract (LVOT) obstruction
- for HOCM maintain afterload, avoid inotropic agents and maintain preload
Valvular Heart Disease
- preop ECHO
- if meets indications have prior to non cardiac surgery to reduce risk
- aortic stenosis
- mitral stenosis
- mitral regurg (left sided > right sided to tolerate anaesthesia
Arrhythmias/Conduction disorders
- AF common - main problem is anticoagulation - bridging clexane with warfarin
- AV block - rarely progress perioperatively. Care with beta-blockade
Pulmonary vascular disease
- pul HTN high risk and need specialist care
- group 1 (pul art HTN)
- high. pul pressures (sys >70)
- mod or greater ventricular dilatation
- pul vasc resis >3 woods units
- NYHA class 3 or 4
Adult congenital heart disease
In a patient with an intermediate risk surgery a TTE is indicated for a patient with unknown exercise tolerance?
False
- CCS guidelines state ECHO has poor risk stratification
- NT-proBNP better predictor
If exam showed AS/HOCM or pul HTN then ECHO should be obtained
ESC - 2 risk factors + high risk surg do an ECHO
Abdominal aortic aneurysm repair with double vessel CAD
which of the following should be considered?
- periop balloon angioplasty
- PCI with bare metal stents
- revascularisation strat best for left main disease
- none of these
coronary revascularisation is before major vascular surgery is recommended
