Intraoperative diagnosis of rate-dependent bundle branch block

Rate-dependent Left Bundle Branch Block during Anaesthesia

Rate-dependent left bundle branch block during general anaesthesia is rare. Its occurrence makes electrocardiographic diagnosis of acute myocardial ischaemia or infarction difficult. It can also be confused with a slow rate ventricular tachycardia. We present a case of rate-dependent left bundle branch block in a patient with no previous history of ischaemic heart disease. Carotid sinus massage resulted in a decrease in heart rate and reversion to normal sinus rhythm.

Rate-related left bundle branch block and cardiac memory in a patient with bradycardia: Case report and literature review

Rate-related left bundle branch block (LBBB) is a well-studied phenomenon. Cardiac memory is another physiologic phenomenon in which T-wave abnormalities occur in the absence of ischemia. The association between these 2 phenomena has been described in several case reports. A literature review was performed through Ovid and PubMed, where at total of 93 cases of rate-related LBBB were identified. Cases were reviewed, and data were collected on rates of appearance and disappearance as well as the presence or absence of cardiac memory. There is some overlap in the rate at which LBBB appears. Cardiac memory is associated with rate-related LBBB in several cases, but its true prevalence is unknown. Cardiac memory is a phenomenon that is well described in the literature but is often underrecognized in clinical practice. As a consequence of overlooking this phenomenon and not including cardiac memory in the differential when T-wave abnormalities are observed, patients may be subjected to unnecessary invasive diagnostic testing.

Rate-Dependent Left Bundle Branch Block in an Ambulatory Surgery Patient: A Case Report

A 52-year-old woman, ASA II (American Society of Anesthesia classification II) scheduled for cholecystectomy in an ambulatory center, exhibited a wide-complex tachycardia with ectopy on the monitor after induction with propofol and succinylcholine. Blood pressure remained stable; amiodarone was administered for presumed ventricular tachycardia. A 12-lead electrocardiogram (ECG) showed a new left bundle branch block (LBBB) at 98 beats per minute (bpm), which resolved when the heart rate slowed. Surgery was postponed, and both the LBBB and ectopy recurred frequently during the next 24 hours in the intensive care unit, particularly at heart rates >90 bpm. Troponins were normal, and the patient was diagnosed with a rate-dependent LBBB and cleared for surgery.

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

BACKGROUND AND OBJECTIVES

Transient changes in intraoperative cardiac conduction are uncommon. Rare cases of the development or remission of complete left bundle branch block under general and locoregional anesthesia associated with myocardial ischemia, hypertension, tachycardia, and drugs have been reported. Complete left bundle branch block is an important clinical manifestation in some chronic hypertensive patients, which may also be a sign of coronary artery disease, aortic valve disease, or underlying cardiomyopathy. Although usually permanent, it can occur intermittently depending on heart rate (when heart rate exceeds a certain critical value).

CASE REPORT

This is a case of complete left bundle branch block recorded in the preoperative period of urgent surgery that reverted to normal intraoperative conduction under general anesthesia after a decrease in heart rate. It resurfaced, intermittently and in a heart-rate-dependent manner, in the early postoperative period, eventually reverting to normal conduction in a sustained manner during semi-intensive unit monitoring. The test to identify markers of cardiac muscle necrosis was negative. Pain due to the emergency surgical condition and in the early postoperative period may have been the cause of the increase in heart rate up to the critical value, causing blockage.

CONCLUSIONS

Although the development or remission of this blockade under anesthesia is uncommon, the anesthesiologist should be alert to the possibility of its occurrence. It may be benign; however, the correct diagnosis is very important. The electrocardiographic manifestations may mask or be confused with myocardial ischemia, factors that are especially important in a patient under general anesthesia unable to report the characteristic symptoms of ischemia.

Case report: transient left bundle branch block associated with ECT

We present the first reported case of transient left bundle branch block (LBBB) occurring during electroconvulsive therapy (ECT). LBBB is an important clinical finding, as it is associated with a significant increase in mortality. Physicians providing ECT should be aware of the significance of new-onset LBBB; it may occur during treatment.

Postoperative episodic left bundle branch block

Transient left bundle branch block (LBBB) associated with physical exertion has been described in patients with and without coronary artery disease. A 64-year-old woman with no history of coronary artery disease underwent Nissen fundoplication under general anesthesia. Preoperatively, an exercise-tolerance test revealed LBBB, without ischemic symptoms. Intraoperatively, the electrocardiogram revealed normal sinus rhythm. Postoperatively, LBBB appeared in the absence of clinical symptoms or physiologic stress. The patient reported several similar episodes previously. Cardiac enzymes were negative. Subsequent electrocardiograms revealed persistence of LBBB. Anesthesiologists should be aware of the possibility of perioperative transient LBBB in the absence of cardiac ischemia.