Lecture: Cardiovascular Diseases for 2nd-Year Anaesthetic

Cardiovascular Diseases

A Comprehensive Lecture for 2nd-Year Anaesthetic Technicians

1. Introduction 2. Pathophysiology 3. Coronary Artery Disease 4. Heart Failure 5. Valvular Disease 6. Arrhythmias 7. Perioperative Management 8. Monitoring & Drugs 9. Case Studies 10. Summary

1. Introduction to Cardiovascular Diseases (CVD)

Cardiovascular diseases remain the leading cause of perioperative morbidity and mortality in surgical patients. As anaesthetic technicians, understanding CVD is critical for:

• Preoperative risk assessment
• Intraoperative hemodynamic management
• Recognizing early signs of decompensation
• Assisting with advanced monitoring and drug administration

Key Statistic: 30% of patients undergoing non-cardiac surgery have CVD or significant risk factors. (Fleisher et al., 2014 ACC/AHA Guideline)

Learning Objectives

1. Identify common CVDs and their pathophysiology
2. Understand anaesthetic implications of each condition
3. Master perioperative monitoring and drug management
4. Recognize red flags requiring immediate intervention

2. Core Pathophysiology Concepts

Cardiac Output (CO) = HR × SV

Stroke Volume (SV) depends on:

• Preload: Venous return (Frank-Starling)
• Afterload: Resistance to ejection (SVR)
• Contractility: Myocardial force (inotropy)

Anaesthetic Implication: All anaesthetic agents affect preload, afterload, and contractility. Volatile agents ↓ contractility and SVR; opioids preserve CO better.

Oxygen Supply-Demand Balance

Supply Factors	Demand Factors
Coronary perfusion pressure	Heart rate
Diastolic time	Wall tension (afterload)
Hb, SaO₂	Contractility

3. Coronary Artery Disease (CAD) & Ischemic Heart Disease

Pathophysiology

Atherosclerotic narrowing → fixed obstruction → supply-demand mismatch during stress.

Perioperative Risk

• Major Adverse Cardiac Events (MACE): MI, ischemia, HF, death
• Risk highest in first 48 hours post-op

Revised Cardiac Risk Index (RCRI) – 6 independent predictors:

1. High-risk surgery
2. History of IHD
3. History of HF
4. History of CVA
5. Diabetes on insulin
6. Cr > 2.0 mg/dL

≥3 factors → >11% risk of MACE

Anaesthetic Management

Goal	Strategy
Avoid tachycardia	β-blockers, opioids, avoid light anaesthesia
Maintain DBP >60 mmHg	Phenylephrine, cautious fluid
Avoid hypoxia/hypercarbia	High FiO₂, normoventilation

Red Flag: New ST depression >1mm or chest pain → notify anaesthetist immediately.

4. Heart Failure (HF)

Types

• HFrEF (≤40%): Systolic dysfunction
• HFpEF (>50%): Diastolic dysfunction, "stiff ventricle"

Perioperative Concerns

• Fluid overload → pulmonary edema
• Low CO → organ hypoperfusion
• Arrhythmias (especially AF)

NYHA Classification:

• I: No limitation
• II: Slight limitation
• III: Marked limitation
• IV: Symptoms at rest → avoid elective surgery

Anaesthetic Goals

• HFrEF: ↑ contractility (inotropes), ↓ afterload (ACEi, hydralazine)
• HFpEF: Control HR (β-blockers), avoid fluid overload
• Avoid hypovolemia and large fluid shifts

5. Valvular Heart Disease

Key Lesions

Lesion	Pathophysiology	Anaesthetic Goal
Aortic Stenosis (AS)	Fixed CO, ↓ coronary perfusion	Avoid ↓SVR, tachycardia, hypovolemia
Mitral Regurgitation (MR)	Volume overload, ↓ forward flow	↓ SVR, avoid ↑ afterload
Aortic Regurgitation (AR)	Diastolic reflux	↑ HR, ↓ SVR

Critical AS (valve area <1.0 cm²): Maintain sinus rhythm, avoid hypotension. Use arterial line mandatory.

6. Common Arrhythmias in Perioperative Period

Atrial Fibrillation (AF)

• Most common
• Risk: hypovolemia, pain, sepsis, electrolyte imbalance
• New-onset AF → rate control (β-blockers, digoxin), anticoagulation if >48h

Bradyarrhythmias

• Sinus bradycardia, AV block
• Treatment: atropine, glycopyrrolate, pacing if symptomatic

Emergency Drugs You Must Know:

• Atropine: 0.5 mg IV, repeat q3–5 min (max 3 mg)
• Adenosine: 6 mg → 12 mg (SVT)
• Amiodarone: 150 mg IV over 10 min (VT/AF)

7. Perioperative Risk Stratification & Management

Preoperative Assessment

• History: exertional dyspnea, angina, syncope
• Functional capacity: >4 METs = low risk
• ECG: look for Q waves, LBBB, AF
• Echo if murmur or poor functional status

Beta-Blockers

• Continue in chronic users
• Do NOT start on day of surgery (POISE trial)

Anticoagulation

• Warfarin: stop 5 days, bridge with LMWH if high risk
• DOACs: stop 48h (renal function dependent)

8. Advanced Monitoring & Pharmacology

Monitoring Tools

• 5-lead ECG: Essential for ischemia detection
• Invasive BP (Art line): AS, HF, major surgery
• CVP: Trend fluid status
• PAC (rare): Only in high-risk cardiac surgery
• TEE: Gold standard for valve/CO assessment

Key Vasoactive Drugs

Drug	Dose	Effect
Phenylephrine	50–100 mcg bolus	↑ SVR
Noradrenaline	0.05–0.1 mcg/kg/min	↑ SVR, ↑ contractility
Dobutamine	2–20 mcg/kg/min	↑ contractility, ↓ SVR
Nitroglycerin	0.5–2 mcg/kg/min	↓ preload, coronary vasodilation

9. Case Studies

Case 1: 68M, AS (valve area 0.8 cm²), for hip replacement

• Art line pre-induction
• Avoid spinal (↓ SVR)
• Phenylephrine ready
• Maintain HR 60–70

Case 2: 75F, CAD, stents 6 months ago, on aspirin + clopidogrel

• Continue aspirin
• Stop clopidogrel 5 days
• High-risk → consider ICU post-op

10. Summary & Key Takeaways

• CVD = major perioperative risk
• Know RCRI, functional capacity, ECG
• Tailor anaesthesia to pathophysiology
• Master monitoring and emergency drugs
• Communication with anaesthetist is critical

Final Word: "The best anaesthetic is the one that maintains homeostasis." – Always think: preload, afterload, contractility, rate, rhythm.

© 2025 Anaesthetic Technician Education Series | For Educational Use Only

References: ACC/AHA Guidelines, ESA Guidelines, UpToDate, Miller's Anesthesia