[Intermittent left bundle branch block - reversal to normal conduction during general anesthesia]

Area of Science:

• Cardiology
• Anesthesiology
• Electrophysiology

Background:

• Complete left bundle branch block (CLBBB) is typically permanent but can be transient and heart-rate-dependent.
• Intraoperative development or remission of CLBBB is rare, often linked to myocardial ischemia, hypertension, tachycardia, or certain drugs.
• CLBBB can indicate underlying cardiac conditions like coronary artery disease, aortic valve disease, or cardiomyopathy.

Observation:

• A case of CLBBB was observed preoperatively, resolving during general anesthesia with a decreased heart rate.
• The CLBBB recurred intermittently and was heart-rate-dependent in the early postoperative period.
• Cardiac muscle necrosis markers were negative, suggesting the CLBBB was not due to acute myocardial infarction.

Findings:

• The transient CLBBB resolved spontaneously during surgery and later during postoperative monitoring.
• Elevated heart rate, potentially due to surgical pain, was implicated as the trigger for the CLBBB.
• The electrocardiographic changes of CLBBB can mimic or mask signs of myocardial ischemia.

Implications:

• Anesthesiologists must be vigilant for the rare occurrence of transient CLBBB during surgical procedures.
• While potentially benign, accurate diagnosis is crucial to differentiate from more serious conditions like myocardial ischemia.
• Recognizing heart-rate-dependent CLBBB is vital for patient management, especially under general anesthesia where symptoms cannot be reported.