Perioperative Management of Angina - A Professor's Lecture for MD Final Exams

The Core Physiologic Framework - Never Forget This

• Coronary perfusion pressure (diastolic BP - LVEDP)
• Diastolic filling time (heart rate - slower = more time)
• Oxygen-carrying capacity (Hb, SaO2)
• Coronary vascular tone (vasospasm vs. dilation)

• Heart rate (most important - also reduces supply)
• Wall stress (afterload x radius / 2 x wall thickness - LaPlace)
• Contractility

Part 1: Preoperative Assessment

Step 1 - Urgency of Surgery (The Non-Negotiable First Step)

• Emergency surgery: Proceed immediately. Risk-stratify clinically, set up appropriate monitoring, and manage risk factors postoperatively. No time for workup.
• Urgent/elective surgery: Proceed through the full stepwise algorithm below.

Step 2 - Identify Active Cardiac Conditions (These STOP Elective Surgery)

• MI within 7 days = "active" condition - do NOT proceed
• MI within 1 month with myocardium still at ischemic risk = also "active" - delay
• Old MI with no ischemic territory at risk = low risk - proceed after full algorithm

Step 3 - Estimate Perioperative MACE Risk (Surgery-Specific + Clinical Risk)

The Revised Cardiac Risk Index (RCRI) - Lee's Index

1. High-risk type of surgery
2. History of ischemic heart disease
3. History of congestive heart failure
4. History of cerebrovascular disease (TIA/stroke)
5. Insulin-dependent diabetes mellitus
6. Preoperative serum creatinine ≥2.0 mg/dL

Cardiac risk (MACE %) by RCRI class and surgical procedure - Barash's Clinical Anesthesia 9e

Step 4 - Functional Capacity (Metabolic Equivalents - METs)

The Full ACC/AHA Decision Algorithm

Stepwise perioperative cardiac assessment for CAD - Morgan & Mikhail's Clinical Anesthesiology 7e (ACC/AHA 2014)

1. Emergency? → Proceed, manage clinically
2. ACS present? → Cardiology referral, GDMT (STEMI/NSTEMI CPGs)
3. Estimate MACE risk (RCRI + surgical risk)
   • Low risk (<1%) → No further testing, proceed
   • Elevated risk → Go to functional capacity assessment
4. Functional capacity ≥4 METs?
   • Moderate/good (4-10 METs) → Proceed (Class IIb: no further testing)
   • Excellent (>10 METs) → Proceed (Class IIa)
   • Poor or unknown (<4 METs) → Question 5
5. Will further testing change management?
   • Yes → Pharmacologic stress testing (Class IIa). If abnormal → coronary revascularization per existing CPGs
   • No → Proceed per GDMT or consider alternate/palliative strategy

Preoperative Testing - When to Order What

• Indicated for patients with known CAD, significant arrhythmia, peripheral artery disease, cerebrovascular disease prior to intermediate/high-risk surgery (Class IIa)
• May be considered in asymptomatic patients before intermediate/high-risk surgery (Class IIb)
• NOT useful in asymptomatic patients before low-risk surgery (Class III)

• If dyspnea of unknown origin
• Known LV dysfunction - if no echo within 1 year or significant functional change

• Reserve for elevated RCRI risk + poor/unknown functional capacity (<4 METs) + testing will change management
• Pharmacologic stress (dobutamine stress echo, nuclear perfusion imaging) when patient cannot exercise
• NOT recommended for low-risk surgery or good functional capacity (>4 METs)

Part 2: Preoperative Medical Optimization

Beta-Blockers - The Most Exam-Relevant Drug

1. Continue beta-blockers in patients already receiving chronic therapy - do NOT withdraw (evidence A)
2. Never start beta-blockers de novo on the day of surgery
3. Consider initiating beta-blockade perioperatively (titrated, well in advance) in very select patients: intermediate/high-risk ischemia on stress testing, OR ≥3 RCRI risk factors

Statins

• Continue existing statin therapy perioperatively (evidence B) - important for plaque stabilization, anti-inflammatory effects
• Initiate statin therapy for patients undergoing vascular surgery (evidence B)
• Multiple trials show reduced perioperative MACE and mortality, especially in vascular surgery
• The LOAD trial showed no benefit from atorvastatin loading in statin-naive patients for non-vascular surgery - so be selective

ACE Inhibitors / ARBs

• Continue for heart failure or hypertension management (maintain RAAS continuity)
• Hold on the morning of surgery if used solely for hypertension - reduces risk of severe intraoperative hypotension
• Resume postoperatively when hemodynamically stable

Aspirin / Antiplatelet Therapy

• Continuing aspirin does NOT prevent cardiovascular complications perioperatively
• BUT does increase major bleeding risk (which is itself a risk factor for perioperative stroke)
• General recommendation: hold aspirin 72 hours before surgery for most patients
• Exception: consider continuing in patients with high-risk atherosclerotic CVD or recent stroke within 9 months

• Most dangerous period: 4-6 weeks post-stent implantation (highest stent thrombosis risk)
• DAPT (Dual Antiplatelet Therapy) duration:
  • BMS (bare metal stent): minimum 30 days DAPT before elective surgery
  • DES (drug-eluting stent) for stable disease: minimum 6 months DAPT
  • DES post-ACS: minimum 12 months DAPT
• Drug washout before surgery: clopidogrel - 5 days; prasugrel - 7 days; ticagrelor - 3-5 days
• If surgery truly cannot be delayed: continue aspirin, discuss with cardiology

Prophylactic Revascularization - A Common Misconception

Part 3: Intraoperative Management

Monitoring

• 5-lead ECG with ST-segment monitoring: leads II (inferior territory), V4 or V5 (anterior/lateral territory - most sensitive for LAD ischemia). Combination of II + V5 detects ~80% of ischemic events
• Arterial line for continuous BP monitoring in moderate/high-risk cases
• Central venous access as indicated
• TEE (transesophageal echocardiography): The most sensitive intraoperative monitor for ischemia - detects new regional wall motion abnormalities (RWMA) before ECG changes or hemodynamic compromise. Gold standard for high-risk cases. (Miller's Anesthesia 10e, p. 3457)
• Pulmonary artery catheter: selected cases with severe LV dysfunction or anticipated major fluid shifts

Anesthetic Goals - The Hemodynamic Targets

Choice of Anesthetic Technique

Intraoperative Ischemia - Recognition and Treatment

• ST depression >1 mm in two contiguous leads (subendocardial ischemia - most common pattern)
• ST elevation (transmural ischemia - more alarming)
• New T-wave inversions
• New LBBB

• Drug of choice for acute intraoperative ischemia
• Works via systemic venodilation (↓ preload, ↓ LVEDP) + coronary arterial dilation including collateral beds
• Effective at stenosed coronaries
• Caution: Higher doses cause systemic hypotension → reflex tachycardia → worsens ischemia
• Prophylactic nitroglycerin infusion does NOT prevent intraoperative ischemia or reduce cardiac complications
• Side effect at high/prolonged doses: methemoglobinemia

Part 4: Postoperative Management

High-Risk Period

1. Plaque rupture + thrombosis (most common - similar to spontaneous ACS)
2. Demand ischemia from tachycardia, hypotension, pain, anemia, hypoxia

Postoperative Monitoring

• Routine ECGs and troponins are NOT recommended in all patients
• In high cardiac risk patients: the benefit of routine troponin/ECG surveillance remains uncertain
• Any symptomatic event (chest pain, new hemodynamic instability, new arrhythmia, hypoxia): obtain ECG and troponin immediately and treat as ACS

Postoperative Treatment

• Treat as standard ACS protocol
• Key caveat: Bleeding risk from anticoagulants must be carefully weighed against thrombotic risk given recent surgery
• Dual antiplatelet therapy decisions require surgical team input regarding bleeding risk
• Urgent cardiology consultation
• Consider coronary angiography/PCI timing based on clinical stability and surgical bleeding risk

Continue Chronic Medications

• Resume beta-blockers, statins, ACE inhibitors/ARBs postoperatively as soon as patient is hemodynamically stable and tolerating oral medications
• Abrupt beta-blocker withdrawal perioperatively is associated with rebound tachycardia, hypertension, and ischemia

Summary Table for Exam Revision

Exam Hot Tips

1. The single most important intraoperative monitor for ischemia = TEE (wall motion abnormalities precede ECG changes)
2. Tachycardia is the most dangerous hemodynamic derangement in ischemic heart disease - it both increases demand AND decreases supply
3. POISE trial lesson = high-dose perioperative beta-blocker initiation reduces MI but increases stroke and death; always titrate slowly in advance
4. Prophylactic revascularization before noncardiac surgery is NOT indicated (CARP trial)
5. <4 METs = poor functional capacity = increased perioperative cardiac risk
6. Nitroglycerin prophylaxis infusion = does NOT prevent intraoperative ischemia
7. DES stent = minimum 6 months (stable) or 12 months (post-ACS) before elective surgery to complete DAPT
8. Most perioperative MIs are silent - don't wait for chest pain postoperatively in a sedated patient

Cardiac Arrest in the Operating Theatre - A Professor's Teaching Lecture for MD Final Viva

Section 1: Epidemiology and Why the OT is Unique

• Cardiac arrest occurs in approximately 1 in every 10,000 anesthetics when the cause is anesthesia-related
• Data from the ACS NSQIP database shows a broader incidence - 1 in every 203 surgical patients - with over 70% dying within one month
• When cardiac arrest is purely anesthesia-related, successful resuscitation occurs approximately 90% of the time
• Overall in-hospital survival to discharge is ~25% for perioperative cardiac arrest

1. The patient is already fully monitored - you see it the moment it happens
2. There is immediate expert personnel present
3. All resuscitation equipment is at hand - defibrillator, drugs, airway

Section 2: Classification of Causes - The "ANESTHESIA + H's & T's" Framework

1. Anesthesia/surgery-specific causes (unique to OT)
2. General ACLS causes (H's and T's - same as anywhere else)

Stream A: OT-Specific Causes (The Examiner's Favorites)

1. Airway Catastrophe - Hypoxia from Failed Intubation / Oesophageal Intubation

2. Drug-Related Causes

• Epinephrine IV is the first-line drug - 0.1-0.5 mg (1:10,000) IV boluses, escalating as needed. NOT just IM.
• Stop the trigger
• Aggressive IV fluids (1-2 L rapid)
• Bronchodilators (salbutamol nebulized or IV)
• Antihistamines and corticosteroids are secondary

• Stop injection immediately
• Airway management, 100% O2, IV access
• Seizures: benzodiazepine (NOT propofol - cardiovascular depression)
• 20% Lipid Emulsion (Intralipid) - the specific antidote:
  • Bolus: 1.5 mL/kg over 1 minute
  • Infusion: 0.25 mL/kg/min
  • Repeat bolus every 3-5 min if no response
  • Maximum total dose: 10 mL/kg over first 30 minutes
• For cardiac arrest: standard ACLS + lipid emulsion
• Avoid propofol as lipid emulsion substitute (insufficient lipid load, adds cardiac depression)

3. Total Spinal / High Spinal Anesthesia

• Hand/arm tingling (cervical root involvement)
• Intercostal paralysis
• Diaphragm paralysis (C3-5)
• Apnea + LOC (brainstem)
• Cardiac arrest

• 100% O2, secure airway (intubate)
• Vasopressors (epinephrine/phenylephrine IV) for hypotension
• Atropine/epinephrine for bradycardia
• Psychological support and reassurance (patient may be conscious initially)
• Block resolves with time - generally recovers fully

4. Malignant Hyperthermia (MH)

• Stop trigger agents immediately
• Call for help + MH hotline
• Dantrolene 2.5 mg/kg IV rapidly, repeat until ETCO2 falls (continue until crisis resolves, up to 10 mg/kg or more)
• 100% O2 at high flows to wash out volatile agents
• Active cooling (cold IV fluids, ice packs, cooled lavage)
• Treat hyperkalemia aggressively (cardiac arrest from K+ is a major risk)
• Bicarbonate for severe acidosis
• Continue surgery only if life-threatening

5. Venous Air Embolism (VAE)

• Flood surgical field / stop air entry
• Aspirate via right heart/CVP catheter
• Place patient left lateral decubitus + Trendelenburg (Durant maneuver) - moves air bubble away from right ventricular outflow tract
• 100% O2 to dissolve air (NO nitrous oxide - it expands air bubble)
• CPR if arrest occurs - chest compressions may fragment large bolus

6. Tension Pneumothorax

7. Cardiac Tamponade

8. Acute Coronary Syndrome / Massive MI

Stream B: The H's and T's (AHA 2020 ACLS Guidelines)

Section 3: Recognition in the OT

• SpO2 waveform loss (first sign often)
• ETCO2 sudden drop to zero (no cardiac output = no CO2 delivery to lungs)
• Arterial line trace goes flat
• ECG: VF, pulseless VT, asystole, PEA
• Surgical field: sudden "empty" vessels, no bleeding

• During good CPR, ETCO2 should be >10 mmHg
• ETCO2 >40 mmHg during CPR = very likely ROSC
• Helps guide compression quality without interrupting CPR

Section 4: The OT Cardiac Arrest Algorithm - 2020 AHA / 2023 ESAIC-ESTES

Immediate Response (First 30 seconds)

1. Call for help - designate team leader immediately
2. Confirm cardiac arrest - pulse check <10 seconds
3. Start high-quality CPR - 30:2 if not intubated; continuous compressions if intubated
4. Apply defibrillator pads
5. Assess rhythm

CPR Quality Standards (2020 AHA)

Shockable vs. Non-Shockable Rhythms

• Shock immediately: Biphasic 120-200J, monophasic 360J
• Resume CPR immediately after shock (do NOT check pulse first)
• Epinephrine 1 mg IV every 3-5 minutes (after 2nd shock)
• Amiodarone 300 mg IV bolus (after 3rd shock) - for refractory VF/VT
• Internal defibrillation (open chest): 10-50J if chest is open

• CPR immediately
• Epinephrine 1 mg IV as soon as possible, then every 3-5 minutes
• Identify and treat H's and T's
• Atropine: NOT recommended for asystole/PEA (insufficient evidence, not harmful but not helpful)

• All benefit comes from alpha-adrenergic vasoconstriction
• Increases aortic diastolic pressure → increases coronary perfusion pressure → improves myocardial blood flow
• Beta effects are actually detrimental (increase post-ROSC arrhythmias and O2 demand)

Section 5: OT-Specific Modifications to Standard ACLS

1. Airway advantage: The anesthesiologist can maintain a definitive airway immediately - use it. Continuous capnography during CPR is essential.
2. Open Chest Cardiac Massage (OCCM): In cardiac surgery cases or when chest is already open - internal cardiac massage is far more efficient than external compressions (generates higher cardiac output). Use internal paddles for defibrillation starting at 10J.
3. Position: External CPR in prone-positioned patients - place pads at T7 and right shoulder; compressions at same location as standard. Do NOT routinely reposition prone patients unless compressions are completely ineffective.
4. Drug delivery: Intraosseous (IO) access - humeral IO is rapid and allows 100 mL/min flow. If no IV access, use IO. Do NOT use endotracheal route as primary route.
5. TEE: Provides real-time diagnosis of cause (wall motion abnormality, pericardial effusion, RV failure, PE) without interrupting compressions. Gold standard for intraoperative diagnosis.
6. Surgical control of hemorrhage: If cardiac arrest is due to surgical hemorrhage, surgical hemostasis takes priority alongside CPR.
7. REBOA (Resuscitative Endovascular Balloon Occlusion of the Aorta): In select trauma cases, can temporize hemorrhagic cardiac arrest by occluding descending aorta - complex, requires specific training and infrastructure.

Section 6: Drugs in OT Cardiac Arrest - Quick Reference

Section 7: Post-Resuscitation Care (Post-ROSC)

Post-Cardiac Arrest Care Algorithm - AHA 2020 (Barash's Clinical Anesthesia 9e)

Initial Stabilization Phase:

• Secure airway with ETT + confirm with waveform capnography
• Ventilate at 10 breaths/min (start)

• Titrate FiO2: SpO2 92-98% (avoid hyperoxia - generates free radicals)
• Titrate ventilation: PaCO2 35-45 mmHg (avoid hypocapnia - causes cerebral vasoconstriction)

• Systolic BP >90 mmHg, MAP >65 mmHg
• Vasopressors/inotropes as needed

Continued Management:

• If patient is comatose (not following commands) after ROSC → TTM at 32-36°C for 24 hours
• Prevents secondary neurological injury from reperfusion
• Use cooling device with feedback loop
• Monitor core temperature continuously (esophageal, rectal, bladder)
• TTM + EEG monitoring + brain CT are all part of the comatose post-arrest bundle

• Maintain normoglycemia (hyperglycemia worsens neurological outcome)
• Continuous or intermittent EEG (detect subclinical seizures)
• Lung-protective ventilation
• Avoid hyperthermia after TTM completion

Section 8: DNAR Orders in the OT

• Up to 60% of anesthesiologists mistakenly believe DNAR orders are automatically suspended in the OT
• This is legally and ethically wrong - advance directives are binding
• ASA, American College of Surgeons, AORN, and The Joint Commission all require reconsideration, not abandonment, of DNAR in the perioperative period
• The discussion must occur preoperatively, must be documented, and must be shared with the full OT team
• Families have successfully sued for damages when DNAR instructions were ignored

Section 9: Prevention - The Anesthesiologist's Priority

VIVA QUESTIONS - Rapid Fire

Approximately 1 in 10,000 anesthetics when purely anesthesia-related; 1 in 203 surgical patients in the broader NSQIP database.

Because patients are already fully monitored, arrest is recognized immediately, expert personnel are present, and all resuscitation equipment is immediately available. When anesthesia-related, ROSC approaches 90%.

H's: Hypovolemia, Hypoxia, Hydrogen ion (acidosis), Hypo/Hyperkalemia, Hypothermia, Hypoglycemia. T's: Tension pneumothorax, Tamponade, Toxins, Thrombosis-pulmonary, Thrombosis-coronary.

Epinephrine 1 mg IV every 3-5 minutes. Its benefit is entirely through alpha-adrenergic vasoconstriction - increases aortic diastolic pressure → raises coronary perfusion pressure → improves myocardial blood flow. Beta effects are not beneficial during arrest.

Tension pneumothorax. Stop ventilation briefly to confirm, immediately perform needle decompression at 2nd intercostal space, midclavicular line, followed by intercostal tube thoracostomy. Do NOT wait for CXR in haemodynamic compromise.

Succinylcholine-induced hyperkalemia. Upregulation of extrajunctional acetylcholine receptors causes massive K+ efflux. Treatment: standard CPR, calcium gluconate 10 mL IV (membrane stabilization), insulin + dextrose, sodium bicarbonate. Avoid succinylcholine in any patient with >4 days of denervation, burns, prolonged immobilization, or critical illness.

LAST - Local Anesthetic Systemic Toxicity. Specific treatment is 20% lipid emulsion: 1.5 mL/kg bolus over 1 minute → infusion at 0.25 mL/kg/min. Repeat bolus every 3-5 min. Maximum 10 mL/kg over 30 min. Standard ACLS simultaneously. Avoid propofol as a substitute - it adds cardiovascular depression and the lipid concentration is insufficient.

Unexplained tachycardia + rising ETCO2 (most important early sign) + masseter spasm (after succinylcholine) + metabolic acidosis + hyperkalemia + hyperthermia (late). Specific treatment: Dantrolene 2.5 mg/kg IV bolus (repeat until ETCO2 falls), plus stop triggers, active cooling, treat hyperkalemia. Dantrolene prevents Ca2+ release from sarcoplasmic reticulum by blocking RYR1 channels.

Single biphasic shock (120-200J; manufacturer-specific) → immediate CPR resumption (do NOT pulse check) → 2 minutes CPR → rhythm check. If VF persists: shock → CPR. Epinephrine 1 mg IV after 2nd shock. Amiodarone 300 mg IV after 3rd shock. Internal defibrillation (open chest): start at 10J, increase as needed.

After the 3rd failed defibrillation attempt in refractory VF or pulseless VT. Dose: 300 mg IV rapid bolus during arrest, then 150 mg supplements as needed. Maximum 2g/day. It improves survival to hospital admission (3 randomized trials) but has not shown survival to discharge benefit. Lidocaine 1-1.5 mg/kg is the alternative if amiodarone is unavailable.

The ABCDE approach: (A) Oesophageal intubation / tube displacement, (B) Circuit disconnection, (C) Cardiac arrest / massive pulmonary embolism (no blood reaching lungs), (D) Massive air embolism. First check patient (is pulse present?), check airway, check circuit. ETCO2 also correlates with CPR quality - a rising ETCO2 during CPR indicates improving cardiac output.

Per 2023 ESAIC guidelines: place defibrillator pads at T7 (posterior) and right shoulder (anterior). Compressions are applied at the same position as standard (lower third of sternum against the table). Do not routinely turn the patient supine unless compressions are definitively ineffective - repositioning wastes critical time.

Targeted Temperature Management at 32-36°C for 24 hours in comatose patients (those not following commands) after ROSC. Reduces secondary neurological injury from reperfusion. Do NOT allow hyperthermia. Monitor temperature continuously. Accompany with EEG monitoring (detect subclinical seizures), brain CT, and normoglycemia. Neuroprognostication should not occur before 48-72 hours post-arrest.

No. This is a common misconception - 60% of anesthesiologists erroneously believe this. DNAR must be reconsidered, not abandoned in the perioperative period. Anesthesiologist must discuss with patient, document the agreement, and communicate with the full OT team preoperatively. Advance directives are legally binding. Courts have awarded damages when DNAR was overridden without consent.

TEE is the gold standard intraoperative diagnostic tool during cardiac arrest. It can identify: new RWMA (myocardial infarction), pericardial effusion/tamponade, right heart failure (PE), hypovolemia (empty heart), massive air embolism, and the adequacy of compressions - all without interrupting CPR. The 2023 ESAIC guidelines support its use in the OT setting.

Summary Framework for Exam

Cardiac Arrest in OT
│
├── RECOGNIZE (< 10 sec): Monitor loss, no pulse
│
├── CALL FOR HELP + START CPR (100-120/min, 5-6 cm)
│
├── DEFIBRILLATOR ON → Shockable? → Shock + CPR
│                                ↓ Non-shockable?
│                              CPR + Epinephrine
│
├── FIX THE CAUSE (H's & T's + OT-specific)
│   ├── Airway failure → Reoxygenate, eFONA
│   ├── Anaphylaxis → Epinephrine IV + fluids
│   ├── LAST → Lipid emulsion 20%
│   ├── Total spinal → Airway + vasopressors
│   ├── MH → Dantrolene + cooling
│   ├── VAE → Durant maneuver + O2
│   ├── Tension PTx → Needle decompression
│   ├── Tamponade → Pericardiocentesis
│   └── Hyperkalemia → Ca2+, bicarb, insulin
│
└── POST-ROSC → TTM (if comatose), STEMI? → Cath lab
                 SpO2 92-98%, PaCO2 35-45, MAP >65

• Barash's Clinical Anesthesia 9e, Chapter 58 (pp. 4896-4948)
• Miller's Anesthesia 10e (pp. 634, 6127, 1973)
• Hinkelbein J et al. "Cardiac arrest in the perioperative period: a consensus guideline." Eur J Anaesthesiol. 2023 Oct (PMID: 37218626) - ESAIC/ESTES Practice Guideline
• AHA 2020 Guidelines for CPR and ECC (Circulation. 2020;142:S366-S468)
• ASRA Local Anesthetic Systemic Toxicity Checklist (2020)
• Morgan & Mikhail's Clinical Anesthesiology 7e