What preoperative clearance is needed for an elderly female patient with a 20+ year history of Right Bundle Branch Block (RBBB), well-controlled Hypertension and Type 2 Diabetes, scheduled for Total Knee Arthroplasty (TKA)?

Preoperative Clearance for TKA with Chronic RBBB, Controlled HTN, and Type 2 Diabetes

This patient requires a focused cardiovascular assessment including ECG, evaluation for cardiac autonomic neuropathy, and glucose control verification, but the chronic stable RBBB itself does not require additional cardiac testing or delay surgery. 1

Essential Preoperative Workup

Cardiovascular Assessment Required

Obtain a current ECG to compare with prior tracings and evaluate for:

• New ischemic changes or silent myocardial infarction 1
• Tachycardia or arrhythmias beyond the baseline RBBB 1
• Prolonged QTc interval (>440 ms suggests cardiac autonomic neuropathy) 1
• Signs of progression from isolated RBBB to more advanced conduction disease 1

The 20+ year history of stable RBBB is reassuring—this is a chronic finding that does not independently require cardiology consultation or stress testing for intermediate-risk surgery like TKA. 2

Diabetes-Specific Cardiac Evaluation

Screen for cardiac autonomic neuropathy (CAN) given the diabetes history, as this significantly impacts perioperative risk: 1

• Check for symptoms: permanent tachycardia, orthostatic hypotension, post-prandial hypotension, or severe hypoglycemia without warning symptoms 1
• Measure orthostatic vital signs: BP supine after 10 minutes, then at 1,2, and 3 minutes standing—a drop of ≥20 mmHg systolic (or ≥10 mmHg diastolic) indicates serious sympathetic dysfunction 1
• Perform respiratory heart rate variability testing: deep breathing test analyzing HR variations during 6 cycles of deep respiration over 1 minute 1

If CAN is confirmed by two abnormal tests or symptomatic findings, plan for intra- and postoperative monitoring in a high-dependency unit. 1

Risk Stratification for Silent Ischemia

Calculate the Lee (Revised Cardiac Risk Index) score: 1

• If score ≥2 AND functional capacity <4 METs, refer to cardiology for ischemia testing 1
• If score <2 OR functional capacity ≥4 METs, proceed without stress testing 1

For this patient, risk factors include diabetes and likely age >70, potentially yielding a Lee score of 1-2. Assess functional capacity by asking if she can climb two flights of stairs or walk four blocks without symptoms. 1

Do not routinely screen for silent myocardial ischemia unless she has: 1

• Other arterial damage (cerebrovascular disease, peripheral arteriopathy)
• Macroproteinuria or renal failure
• Coronary calcium score >400 Agatston units (if previously obtained)
• Lee score ≥2 with poor functional capacity 1

Diabetes Management Assessment

Verify current glycemic control: 1

• Check HbA1c if not done within 3 months 1
• Assess for diabetic complications: nephropathy (check creatinine, urinalysis for proteinuria), neuropathy, retinopathy 1
• Review current medications and insulin regimen 1

Screen for microangiopathic complications as these increase cardiovascular risk and warrant CAN testing: 1

• Urinary test strip for proteinuria 1
• Serum creatinine for renal function 1

Hyperglycemia alone does not delay surgery unless the patient is ketotic or severely dehydrated. 3

What Does NOT Need to Be Done

Do not order: 2

• Routine echocardiography (only if symptoms of heart failure or unexplained dyspnea)
• Stress testing for stable, asymptomatic patients with chronic RBBB
• BNP/pro-BNP unless cardiac ischemia is suspected 1
• Cardiology clearance for isolated chronic RBBB without symptoms

Do not delay surgery for "optimization" of chronic stable conditions—the RBBB has been present for 20+ years and represents her baseline. 3

Anesthetic Considerations

Regional anesthesia (spinal/epidural) is preferred for TKA in diabetic patients as it: 1, 3

• Reduces sympathetic hyperactivity 1
• May improve outcomes in patients with cardiac autonomic neuropathy 3
• Allows better postoperative pain control and early mobilization 3

However, be aware that neuraxial anesthesia increases risk of perioperative hemodynamic instability in diabetic patients with CAN. 1

Critical Pitfalls to Avoid

• Do not assume RBBB is entirely benign: While the chronic nature is reassuring, recent data suggests RBBB may be associated with increased cardiovascular mortality even without overt CVD 4, 5
• Do not miss cardiac autonomic neuropathy: This is the most important modifiable risk factor in diabetic patients undergoing surgery and requires specific testing 1
• Do not order unnecessary cardiac testing: Stable chronic RBBB without symptoms does not require stress testing or cardiology consultation for intermediate-risk surgery 2
• Do not delay surgery for chronic conditions: Well-controlled hypertension and diabetes do not require delay 3

Summary Algorithm

1. Obtain current ECG → compare to prior, look for new changes 1
2. Calculate Lee score + assess functional capacity → if score ≥2 AND <4 METs, refer cardiology 1
3. Screen for CAN: orthostatic vitals + respiratory HR variability testing 1
4. Check diabetes control: HbA1c, creatinine, urinalysis 1
5. If CAN confirmed → plan high-dependency monitoring 1
6. Proceed to surgery with regional anesthesia preferred 1, 3