Preoperative Cardiac Evaluation Prepared for KMRH residents in Anaesthesia July 2013 Kabul

Preoperative Cardiac Evaluation Risk assessment – Patient and Surgical Factors Pre-operative Interventions to modify risk Intra-operative Interventions to modify risk Post Operatively Surveillance

Preoperative Cardiac Evaluation Risk assessment : Patient Factors Congestive Heart Failure MI within 30 days Severe Cardiac Arrhythmia including heart block Severe Valvular disease Severe or Unstable angina Other - Remote MI, Diabetes, Renal dysfunction, Poorly managed hypertension, Rhythm other than sinus, Previous or compensated CHF, stable angina treated hypertension, LVH or LBBB, advanced age

Preoperative Cardiac Evaluation Patient Factors Congestive Heart Failure MI within 30 days Severe Cardiac Arrhythmia including heart block Severe Valvular disease Severe or Unstable angina These are severe clinical indicators and patients should be evaluated and optimized preoperatively

Preoperative Cardiac Evaluation Patient Factors Other - Remote MI, Diabetes, Renal dysfunction, Poorly managed hypertension, Rhythm other than sinus, Previous or compensated CHF, stable angina These are intermediate clinical indicators that may or may not need further evaluation depending on their functional capacity and nature of surgery.

Preoperative Cardiac Evaluation Patient Factors Functional capacity – is the patient able to : Class I – Angina only during strenuous or 8-10 METS prolonged physical activity Class II – Slight limitation, with angina only 6-8 METS during vigorous physical activity Class III –Symptoms with everyday living 4-6 METS activities, i.e., moderate limitation Class IV – Inability to perform any activity < 4 METS without angina or angina at rest, i.e.,severe limitation

Cardiac Risks of Noncardiac Surgery Surgical Factors Cardiac stress is inherent to surgery Anaesthetic technique, drugs, pain, and nature of the Surgery all effect : 1. The stress response and catecholamines – increase HR and BP 2. Fluctuations in HR, BP, intravascular volume, oxygenanation, and oxygen transport These factors will cause imbalance in myocardial O2 supply and demand Inhalational agents cause afterload reduction, decreased contractility. Spinal anesthesia causes sympathetic blockade with decrease in preload and afterload, fluid shifts.

Cardiac Risks of Non-cardiac Surgery Myocardial Oxygen Supply and Demand increased HR decreased HR increased Systolic BP increased Diastoloic BP increased wall tension reduced wall tension increases chamber pressure decreased chamber pressure adequate coronary circulation inadequate coronaries adequate hemoglobin Supply Supply

Surgery-specific risks High risk (>5% cardiac risk) Emergency major operations Especially in the elderly Aortic or major vascular surgery Extensive operations with large volume shifts or blood loss.

Surgery-specific risks Intermediate risk (<5% cardiac risk) Intraperitoneal and intrathoracic Carotid endarterectomy Head and neck Orthopedic Prostate

Surgery-specific risks Low risk surgeries (<1% cardiac risk) Endoscopic procedures Superficial biopsies Cataracts Breast surgery

Assessing the situation Determine the urgency for surgery Emergency Surgery – few options – do the best you can Options to consider (as a team) Postpone or cancel Modify the surgical procedure Delay case (for further testing or patient optimization) Perioperative medical therapy Perioperative monitoring Modification of the location of care This is often done for us. Hence, this presentation deals largely with the elective or semi-urgent surgery, during which time the case may be considered and options explored. However, one may be called upon even in the emergent setting. In this case, the consultant in medicine should focus on perioperative medical management, surveillance, and post-operative risk stratification

Pre-operative Interventions to Modify Risk Investigations EKG – suitable for most patients over 40 with risk factors CXR - if any concern from history or physical examination Bloodwork – if significant co-morbidities or chance of significant blood loss Consultation – changing nature of symptoms ( eg worsening angina ) or concern regarding valvular integrity or ventricular function Testing may include echocardiography or cardiac stress testing Medications may be adviseable – B blockers, statins, ASA, others Invasive intervention should be based on symptoms, not surgery

Intra-operative Interventions to Modify Risk Consider : Anaesthetic Technique Intra operative Monitoring Choice of Drugs Post operative analgesia Post operative care

Intra-operative Interventions to Modify Risk: Anaesthetic Technique Regional Anaesthesia – Minimizes the hormonal stress response Spinal/Epidural techniques require consideration of hemodynamic changes Never been shown superior or safer to GA Some benefit to graft patency for peripheral vascular surgery

Intra-operative Interventions to Modify Risk: Choice of Drugs Optimization of myocardial O2 supply/demand is the goal !!! B blockers pre or intra operatively may reduce incidence of adverse cardiac events , may increase risk of cerebrovascular events All volatiles (except N2O) are vasodilators and reduce contractility – so they may reduce demand, but also reduce supply ! Some ( sevoflurane ) may have intrinsic cardio-protective effects Vasopressors alpha agents ( neosynephrine ) may help increase coronary perfusion pressure and may be useful in conjunction with B blockers

Intra-operative Interventions to Modify Risk Choice of Drugs Ketamine increases HR and contractility but may minimize post induction hypotension – consider combining it with midazolam to reduce unwanted effects NTG enhances coronary perfusion but reduces BP and filling pressure ACE inhibitors and Angiotensin receptor blockers Beware as they may cause profound post induction hypotension unresponsive to sympathomimetics – may require small dose vasopressin (0.4 U) Post op Analgesia will reduce the stress response if adequate. Consider multimodal approach including neuraxial opioids ( if appropriate monitoring available )

Intra-operative Interventions to Modify Risk: Monitoring Invasive monitoring may assist in guiding fluid management, provide early warning to hemodynamic changes, and allow blood analysis EKG additional leads ( 5 lead ) may allow detection of up to 70 % of ischemic events

Post Operative Surveillance Post operative cardiac events peak at 48 hrs post op Myocardial infarctions are often silent with 50% mortality CHF as a result of remobilization of intra-operative fluids Consider intermediate care area for high risk patients

Preoperative Evaluation Algorithm Putting it all together

Preoperative Evaluation Algorithm Putting it all together For patients with major clinical predictors undergoing non-emergent noncardiac surgery, consider delaying the surgery. Medical management Medical Risk factor modification Consider invasive/non-invasive testing

Preoperative Evaluation Algorithm Putting it all together For patients with intermediate clinical predictors, evaluate functional status. Moderate to good functional status (>4 mets) promps us to look at the procedure itself. Low functional status (<4 METs) may merit further testing. High surgical risk  further testing Intermediate or low surgical risk  likely okay to OR, with risk

Preoperative Evaluation Algorithm Putting it all together For patients without intermediate clinical predictors, moderate to good functional status indicates lowest cardiac risk for all procedures Poor functional status should always prompt us to evaluate the surgical procedure and consider further testing

Preoperative evaluation algorithm Consider noninvasive testing if two or more are present: Intermediate clinical predictors Poor functional capacity High surgical risk procedure

Therapeutic Preoperative Interventions at KMRH Invasive options available ? ( PCTA, stents, CABG ) for severe symptoms Medical optimization Stress testing, Echocardiography may direct you to modify your anaesthetic plans

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