From the Guidelines
Patients with incomplete right bundle branch block (RBBB) and left ventricular hypertrophy (LVH) should undergo careful anesthetic management, prioritizing the maintenance of cardiac function and reserve, as outlined in the 2024 AHA/ACC/ACS/ASNC/HRS/SCA/SCCT/SCMR/SVM guideline for perioperative cardiovascular management for noncardiac surgery 1.
Key Considerations
- Preoperative cardiac evaluation with ECG, echocardiography, and possibly stress testing is essential to assess cardiac function and reserve.
- Continue cardiac medications, including beta-blockers, ACE inhibitors, and statins, through the perioperative period to minimize cardiac risk.
- For induction, use etomidate (0.2-0.3 mg/kg) or propofol with reduced dosing (1-1.5 mg/kg) to minimize hemodynamic effects, as recommended by the American Heart Association 1.
Anesthetic Management
- Maintain anesthesia with volatile agents at 0.5-0.8 MAC or total intravenous anesthesia with propofol (75-150 mcg/kg/min) and remifentanil (0.05-0.2 mcg/kg/min) to reduce the risk of cardiac complications.
- Employ invasive monitoring, including arterial line and possibly central venous pressure monitoring, for major surgeries to closely monitor cardiac function and respond to any changes.
- Avoid significant tachycardia by maintaining heart rate below 90 beats per minute, as tachycardia can worsen myocardial oxygen demand and reduce diastolic filling time.
- Maintain systolic blood pressure within 20% of baseline, using phenylephrine (50-100 mcg boluses) for hypotension and avoiding vasodilators that may cause reflex tachycardia.
Rationale
These precautions are necessary because LVH increases myocardial oxygen demand and reduces coronary perfusion, while RBBB can progress to complete heart block under anesthesia, especially with volatile agents that prolong cardiac conduction 1. By prioritizing the maintenance of cardiac function and reserve, anesthesiologists can minimize the risk of cardiac complications and ensure optimal outcomes for patients with incomplete RBBB and LVH.
From the Research
Incomplete Right Bundle Branch Block and Left Ventricular Hypertrophy
- Incomplete right bundle branch block (IRBBB) is a common electrocardiogram (ECG) finding that can express both benign and pathological patterns 2.
- IRBBB can appear due to various factors, including higher placement of electrodes V1 and V2, pectus excavatum, or in athletes, and is considered a benign pattern unless accompanied by family history, symptoms, or left ventricular hypertrophy (LVH) 2.
- The presence of IRBBB can make it challenging to diagnose LVH using standard ECG criteria, as the QRS voltages used for LVH detection are reduced in IRBBB 3.
Anesthesia Consideration
- There is no direct evidence in the provided studies regarding anesthesia consideration for patients with IRBBB and LVH.
- However, it is essential to note that patients with IRBBB and LVH may have underlying cardiac conditions that require careful consideration during anesthesia 2, 3.
- Further studies are needed to investigate the implications of IRBBB and LVH on anesthesia management.
Differentiation between Left Bundle Branch Block and Left Ventricular Hypertrophy
- Recent studies have highlighted the importance of differentiating between left bundle branch block (LBBB) and LVH, as patients with LBBB may benefit from cardiac resynchronization therapy (CRT), while those with LVH may not 4, 5.
- New strict criteria for diagnosing complete LBBB have been proposed, utilizing longer QRS duration thresholds and requiring the presence of mid-QRS notching/slurring in at least 2 leads 4, 5.
- These criteria may help improve patient selection for CRT and reduce unnecessary device complications and costs 4, 5.