Why do we “preop” a patient?
Minimize peri-operative mortality and morbidity
Minimize surgical delays
Determine post-op disposition
Evaluate patient’s health
Formulate anesthetic plan
Communicate issues among providers
*Gov’t over site requires a pre-anesthesia eval w/in 48 hrs of scheduled surgery
Coronary risk factors
Smoking HTN DBM HLD Family hx Socioeconomic status (access to care)
Comorbidites related to cardiothoracic surgery include:
Respiratory Neurological PVD Renal Thyroid Peptic ulcer disease Past cardiac surgery
Why is knowing about past cardiac surgery important?
Re-do procedures associated with higer blood loss and morbidity
Dental hygiene is important for what type of cardiac disease?
Valvular disease
Criteria for low risk procedures
Low chance of: bleeding long surgery time unlikely to cause surgical stress <1% MACE
Criteria for high risk procedures
High CV morbidity
Longer hospital stays
Higher risk of bleeding
>1% MACE
Major Patient-related risk factors
Unstable angina Recent MI (<6 weeks) Malignant arrhythmias -SVT -2 or 3 degree AV blocks -Symptomatic bradycardia -VT
Intermediate Patient related risk factors
Established CAD Previous MI btwn 6 weeks-3 months prior to surgery Stable angina CHF with EF of < 35% DBM CKD with creat >2.0 CVA
Minor Patient Related risk factors
Previous CABG more than 6 years before
Myocardial revascularization > 3 months negative stress test within the past 2 years
HTN
>70 years of age
AHA recommendations for elective noncardiac surgery following Acute Coronary Syndrome
60 days
What is one of the biggest indicators for post op major adverse cardiac complications?
Heart failure with EF < 30%
AHA recommendations for pt with known valvular disease?
Echo w/in 1 year of surgery
PHTN
High risk complications
Prevent hypoxia and hypercarbia to help with complications
Perioperative myocardial inury (2 stages)
Stunning (temporary)
MI (cell death)
Determinants of perioperative myocardial injury
Disruption of blood flow
Re perfusion of ischemic myocardium
Adverse effects from bypass (inflammatory cascade and immune system activation)
Morbidity and mortality rate of pts with periopertive MI
49% (vs 4% of those that do not)
What is time limit of ischemia before necrosis occurs?
20 minutes
What is the wavefront phenomena?
necrosis starts in the subendocardial region and progresses to the subepicardial region
What is the primary trigger for apoptosis
Acidosis
MI diagnosis
1 biomarker in 99th percentile and any of these symptoms:
ECG changes
Echo with RWMA
Patient symptoms
MI biomarkers
Myoglobin CK CK-MB Troponin LDH
Peroperative MI definition in CABG
elevation of more than 10x the 99th percentile of normal
Which biomarkers show immediately with MI?
None
Order biomarkers occur
Myoglobin - peaks at 4 hours CK - peaks at 16 hours CK-MB - 24 hours Troponins - 24 hours Lactate - 72 hours
What is the most reliable assessment of contractile dysfunction?
TEE - RWMA can occur w/in 10-15 sec of ischemia onset
ECG changes with MY
new Q waves of 0.03 sec
new QRS deflections
ST changes not reliable in OR because of body placement and lead placement, hypothermia, electrolyte imbalances
Parsonnet Index
Risk model derived from 3500 operations to provide approximation of risk based on 47 factors
STS National Adult Cardiac Surgery Database
largest database for nwer risk-adjusted scoring system
100K pts analyzed
30 risk factors
Highest mortality rates seen in renal failure, emergent status, multiple reoperations, and NYHA class IV status
EurosCORE II
20K pts
Most widely used model and current standard for cardiac surgical risk
identifies multiple high risk pt comorbidities - pts are low, med, high risk
OK to assess pt for CABG and valve surgeries, but not combined
Consistent risk factors for cardiac surgery
Every 5 years over age 60 Female EF < 30% Obese Reoperation Type of surgery Emergent surgery
METs
Excellent >10
Good 7-10
Moderate 4-6
Poor < 4
Examples of 4 METs
walking up hill, running short distance
walk 4 city blocks
heavy work around house
1 MET is equal to
basal metabolic rate - 3.5 mL O2/kg/min
Non-Cardiac surgery risk tools
RCRI - evaluates 6 factors but is not surgery specific
ACS-NSQIP - surgery specific risk; preferred tool
Gupta- includes medical therapies
T or F: High risk pts undergoing low risk procedures require ECG
False. Routine ECGs in asymptomatic patients is not useful. However, if surgery is not low-risk, ECG is warranted
T or F: Lab markers for MI are are recommended for pts at high risk of complications that may benefit from an intervention
True
T or F: Beta Blockers should be continued in non-cardiac surgery pts who have been taking these meds
True. Avoids acute withdrawl
T or F: Beta Blockers should be started within 1 day of non-cardiac surgery
False. Increased risk of hypotension, stroke, and death. UNLESS pt at high risk fro MI
T or F: Statins should be continued perioperatively
True. Pts having vascular surgery should have statin treatment initiated.
T or F: Alpha 2 agonists should be initiated before noncardiac surgery
False. Increased risk of cardiac arrest, hypotension, AKI.
T or F: Aspirin therapy in pts w/o stents is not recommended
True. Unless pt risk of MI is higher than surgical bleeding
T or F: RBC transfusion increases O2 carrying capacity of the blood
False. 2,3-DPG and ATP must normalize. Recommend restrict transfusion < 7 g/dL in asymptomatic, hemodynamically stable pts without CAD. In pts with CAD, number is < 8 g/dL unless symptomatic
Standard of care after stent placement is:
Dual anti platelet therapy wit aspirin and a P2Y12 platelet inhibitor. Continued for 6 weeks for bare metal; 1 year for DES.
If pt has angioplasty with no stents, how long should wait before having elective surgery?
2 weeks
IF pt having acute coronary syndrome should wait how long before elective noncardiac surgery?
60 days
How long after DES should pt wait for elective surgery?
6 months
T or F: Evidence is against using preoperative elective PCI to reduce risk of surgery
T. If noncardiac surgery is performed w/in 4 weeks of PCI, 10% chance of cardiac event
BMS - endothelial stent coverage is complete by when? What is the significance?
12 weeks; risk of re-stenosis drops. IF noncardiac surgery w/in 6 weeks of BMS, risk of cardiac complications is 30%
DES
perform better than BMS for 1st year, but similar after. Cause less long-term inflammation.
What three physiologic responses occur after balloon angioplasty?
- Immediate arterial wall recoil w/in 24 hours
- Negative arterial remodeling
- Neointimal hyperplasia response of smooth muscle proliferation and migration
Stent Restenosis peaks when?
4-12 months
When vessel is 50% with symptoms or 70% total, intervention needed
Stent thrombosis
Occurs w/in 30 days. High risk pts have 2.5% chance
What is the most widely used cardiac diagnostic tool
Echo. LV EF, RWMA, Valvular disease
4 classifications of assessing RWMA during echo (LV)
- Normal
- Hypokinetic
- Akinetic
- Dyskinetic/anuerysmal
RV diastolic function can be assessed how during an echo?
IVC. If collapses by 50% on inspiration, RA pressures are normal (<5 mmHg)
Normal Mitral Valve
4-6 cm2
Mitral valve stenosis
Mild - >1.5 cm2
Mod 1-1.5 cm2
Severe - 1cm2
What is important to remember in pts with MS?
Preload
Mitral valve regurg
Common with LV dysfunciton Independent predictor of morbidity and mortality Mild - <30% Mod 30-49% Severe - >50%
Normal aortic valve
2.6-3.5 cm2
Aortic stenosis
Mild - >1.5 cm2
Mod - 1-1.5 cm2
Severe < 1 cm2
Concerns with AS
LVEDP increases - causing LV hypertrophy. Filling becomes dependent on LA contraction, leading to afib. In severe cases, LV systolic function declines
Recommendations fro symptomatic hemodynamically significant AS prior to elective noncardiac surgery
AVR
Aortic regurg
Mild - <30%
Mod - 30-49%
Severe - >50%
Which has higher mortality rate? AR or AS?
AR
Tricuspid regurg
Tricuspid annulus > 4 cm needs surgical correction
Tricuspid stenosis
very rare
Pulmonary Valve regurg
Very rare. PHTN
Pulmonary valve stenosis
Usually congenital. Not well seen on Echo.
Prosthetic valves
Difficult to assess on echo due to acoustic shadows
Stress echo
Pt on treadmill or bike
12 lead ECG and BP
Ischemia dx with ST segment depression > 1 mm, fall in BP, or CP
Limited if pt on BB
Pharmacologic stress test
Pt receives chronotropic/inotropic agent - dobutamine or a vasoldilator like adenosine. Atropine can increase sensitivity of the test
Formula - cardiac output
CO = HR x SV
Formula - SVR
[(MAP - RAP)/systemic blood flow ] x 80
Myocardial Nuclear Scintigraphy
Most common dx tool to evaluate for MI in preop assessment. Performs better than exercise stress test.
CT or PET scan
Radioactive substance is injected and machine picks up the decay around the heart. Areas of scarring won’t have decay.
Mod to large areas of ischemia is associated with high sensitivity for risk of perioperative MI and death. A normal study has a very high negative predictive value
CCT/Cardiac Computed Tomography
256-320 slices of heart
Ionizing radiation is used
Pts HR slowed to 60 bpm with BB to allow for imaging
94% dx of CAD and 99% negative predictive value
*Note. Only validated in pts with no known CAD
Gold standard for evaluating aorta
Cardiac MRI
Function, flow, morphology, tissue eval, perfusion, angiography, metabolic studies of cardiac structures w/o radiation
Gold standard for BiVentricultar volumes, EF, and mass. Also gold standard for myocardial scarring eval, RV eval, and chronic thoracic aneurysm
Negative predicitve value for 3 yr cardiac events is 99%.
Carotid artery stenosis
Major cause of stroke
Bruits on physical exam
US is performed first with CT or MRA performed if needed
Carotid exams should be done if pt has a bruit, hx of CVA, or PVD
Renal artery stenosis
Cause of secondary htn
US performed initiially
Coronary Angiography
Gol standard for coronary anatomy and severity of CAD
Indications: >40 in men, post menopause women, symptoms, LV dysfunction, CV risk factors
PCI has 99% success rate
Must be < 1 yr for pts undergoing CABG
ECG, coag studies H & H, GFR
Must have 5 lead ECG
Contrast dye precautions
Allergies
Anticoagulant and antiplatelet effects
Induce transient HB, QT prolongation, hypotension
Nephropathy - esp pts with DBM, CKD, HF
Avoid hypotension, NSAIDS, provide hydration
Max dose for healthy kidneys is 4 mL/kg
Dx of contrast induced nephropathy
Creat elevation > 0.5 mg/dl or 25% in 48 hours
Creat levels of 1/5 mg/dL or GFR < 60 mL/min red flag
Right side Cath complications
RBBB, Complete HB, Valvular damage, perforation, paradoxical air embolus
Left side cath complications
MI, VF, VT, stroke, thrombus
EP lab - ablation
Catheter in femoral vessels; systemic heparinization required
Mapping areas of arrhythmia
Scar tissue created
Can be long procedures
EP lab - cardioversion
Want to slow accessory pathways - not AV node - avoid BB, verapamil, digoxin. Do use amiodarone, procainamide.
Opioids have no effect on conduction system. Volatile agents depress AV node but also depress accessory pathway conduction so ok to use.
Paralytics that have cholinergic effects (Succ, pancuronium) avoided
Avoid sympathetic stimualtion
Postop care Handoff
What procedure performed TEE results Ease of transitioning from bypass What inotropic support needed Prescribed hemodynamic parameters
Tamponade
hypotension, raised CVP, pulses paradoxus, ECG dampening
Arrhythmias post op
Common
Check electrolytes - K and Mg common causes
Brady most common after valve surgery
Afib most common overall - 90% of pts that were in SR before will return
Complications after cardiac surgery
- Device related infections (IEDs, LVAD) - mortality up to 35%
- Sternal wound infections - 7% mortality rate
- Endocarditis - prosthetic valve