Rate-dependent Left Bundle Branch Research Articles

Paroxysmal Severe Mitral Regurgitation

ObjectiveTo investigate the clinical presentation, pathophysiology, and treatment for "paroxysmal severe mitral regurgitation" (MR), which is an underappreciated cause of heart failure with preserved left ventricular ejection fraction. MethodsWe retrospectively reviewed cases of transient severe MR that were evaluated at Mayo Clinic in Rochester, Minnesota, between January 1, 2006, and December 31, 2019. Paroxysmal severe MR was defined as the appearance of transient severe MR in patients with mild MR at rest, normal left ventricle (LV) size, left ventricular ejection fraction greater than 40%, and absence of obstructive coronary artery disease. ResultsWe identified 6 patients (5 women) with a median age of 68 years. There were 3 distinct mechanisms of paroxysmal severe MR, which we labeled types 1, 2, and 3. Type 1 MR was caused by LV dyssynchrony from a rate-dependent left bundle branch block, which led to apical leaflet tenting and incomplete coaptation. Type 2 MR occurred from mitral annular dilatation during maneuvers that increased left-sided volume. Type 3 MR was caused by coronary artery vasospasm with apical leaflet tenting. Treatments varied depending on the underlying cause and included cardiac resynchronization therapy for type 1, surgical valve replacement for type 2, and medical therapy for type 3. ConclusionParoxysmal severe MR is a rare cause of heart failure in patients with preserved LV function. We have identified 3 distinct mechanisms that can lead to this dynamic process, with treatments varying based on the underlying cause.

Oversensing issues leading to device extraction: When subcutaneous implantable cardioverter-defibrillator reached a dead-end

Subcutaneous implantable cardioverter-defibrillator (S-ICD) implantations are rapidly expanding. However, the subcutaneous detection and interpretation of cardiac signals in S-ICDs is much more challenging than by conventional devices. There is a complete paradigm shift in cardiac signal sensing with subcutaneous signal detection, leading in some cases to oversensing with restricted programming options. The aim of this single-center study was to quantify and describe cases where recurring oversensing made the extraction of the device necessary. Consecutive patients (n = 108) implanted with an S-ICD in our tertiary referral hospital were considered for analysis. Clinical and remote monitoring data were analyzed. The S-ICD had to be explanted in 6 of 108 implanted patients (5.6%) because of refractory oversensing issues: myopotential oversensing, P- or T-wave oversensing, rate-dependent left bundle branch block aberrancy during exercise with R-wave double counting, and R-wave amplitude decrease after ventricular tachycardia ablation leading to noise detection. Seventeen of 108 patients experienced oversensing (15.7%): 9 patients had at least 1 inappropriate charge without a shock (8.3%), 3 patients had at least 1 inappropriate shock (2.8%), and 5 patients had both episodes (4.6%). So far, cardiologists have had to deal with transvenous ICD lead fractures, but signal oversensing without correcting programming option could be the equivalent weakness of S-ICDs, despite an adequate screening.

Rate-dependent left bundle branch block caused by hyperkalaemia.

A 73-year-old male presented to the emergency department with vomiting and diarrhoea. No abnormalities were found on physical examination, besides a blood pressure of 80/40 mmHg. The blood tests showed acute renal insufficiency and a potassium of 9.0 mmol/L (3.5–5.0). The electrocardiogram (ECG) showed atrial fibrillation and the occurrence of a left bundle branch block (LBBB) when the heart rate exceeded 76 beats per minute (Fig. 1). When the heart rate decreased the ECG abnormalities disappeared (Fig. 2). Previous ECGs had never shown LBBB. Fig. 1 Atrial fibrillation and left bundle branch block Fig. 2 Narrow ECG complexes, the left bundle branch block has disappeared

前胸部誘導で著明な陰性T波を認めた, 心拍数依存性左脚ブロック後cardiac memoryの1例

前胸部誘導で著明な陰性T波を認めた, 心拍数依存性左脚ブロック後cardiac memoryの1例

Intraoperative Detection of Rate Dependent Left Bundle Branch Block

Rate dependent left bundle branch block (RDLBBB) is an uncommon case. RDLBBB is defined as an intraventricular conduction defect that may return, if only temporarily, to sinus rhythm at lower heart rates. It appears when the heart rate exceeds a certain critical value. Although RDLBBB is usually benign, its diagnosis and treatment have clinical importance for association of RDLBBB and myocardial ischemia and infarction. Therefore, in the case of detection of intraoperative RDLBBB, a clear differentiation should be done as soon as possible. Also it is important to start appropriate treatment and to do clinical follow-up examination. We report a case of intraoperative RDLBBB during general anesthesia for laparoscopic cholecystectomy in 82 years old female patient who has a history of hypertension.

Rate dependent left bundle branch block: Does it have any effect on the myocardial perfusion SPECT

Dear Sir, the recent issue of Nuclear Medicine Review published an interesting study by Gholamrezanezhad et al. regarding rate dependent left bundle branch block and its effect on myocardial perfusion SPECT [1]. They reported four cases with rate dependent LBBB during exercise stress for myocardial perfusion imaging. Myocardial perfusion SPECT imaging showed no evidence of reversible perfusion defects in three of the patients. They concluded that “maybe it is possible to continue exercise tolerance test (ETT) for those patients undergoing myocardial perfusion scintigraphy and developing rate dependent LBBB”. As the authors themselves mentioned in their study, the number of cases in their case report was not statistically enough to draw any definite conclusion. We would like to report a case with rate dependent LBBB during ETT who developed perfusion defects in the septal wall which disappeared on the Dipyridamole stress imaging. The case was a 45 year old female patient with history of atypical chest pain since 2 years ago. Her rest ECG was normal. The patient had inconclusive ETT one month before. She was referred to our department for myocardial perfusion SPECT for diagnosis of possible coronary artery disease (CAD). Baseline blood pressure was 130/90 mmHg and baseline heart rate was 70. Five minutes after beginning of ETT (stage II of Bruce protocol and at heart rate of 147), the patient developed LBBB on the ECG monitoring (Figure 1). Rate dependent left bundle branch block: Does it have any effect on the myocardial perfusion SPECT

Haemodynamic Benefit of Cardiac Resynchronisation Therapy Requires Left Bundle Branch Block: A Case Report

A 55-year-old woman with dilated cardiomyopathy and rate-dependent left bundle branch block had a cardiac resynchronisation therapy (CRT) device implanted. During implantation, the maximum rate of left ventricular pressure rise (dP/dtmax) was measured invasively. This case presents a description of the acute negative effect of a left bundle branch block on dP/dtmax, and the different effect of CRT on left ventricular haemodynamic function in the presence and absence of a left bundle branch block.

Rate-dependent Left Bundle Branch Block during General Anesthesia - A case report -

Department of Anesthesiology and Pain Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea Rate-dependent left bundle branch block during general anesthesia is rare, but its occurrence makes the electrocardiographic diagnosis of acute myocardial ischemia or infarction difficult. It can also be confused with slow rate ventricular tachycardia. Herein, a case of rate-dependent left bundle branch block, in a patient with no previous history of ischemic heart disease, is reported. The administration of esmolol resulted in a decrease in the heart rate, with reversion to normal sinus rhythm.

Rate-dependent left bundle branch block unmasked by adenosine

Rate-dependent left bundle branch block unmasked by adenosine

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.

Effects of intermittent left bundle branch block on left ventricular diastolic function: a case report

We investigated systolic and diastolic left ventricular function in a patient with an echocardiographically normal left ventricle and rate dependent left bundle branch block. Abnormal activation was associated with asynchronous left ventricular wall motion and secondary changes in filling pattern. The latter were similar to those seen in severe left ventricular disease. When the activation pattern reverted to normal, all of these abnormalities regressed. This case provides further evidence that abnormal activation can, on its own, cause left ventricular diastolic as well as systolic dysfunction.

Assessment of myocardial perfusion with thallium-201 scintigraphy in exercise-induced left bundle branch block: diagnostic value and clinical significance.

Myocardial perfusion scintigraphy with thallium-201 was performed in 33 subjects (mean age 45 years, range 28-61) with exercise-induced, rate-dependent left bundle branch block (LBBB) in order to assess both the value of Thallium-201 myocardial imaging for the diagnosis of coronary artery disease (CAD) and the pathogenesis (ischaemic or not) of the conduction defect. Of the 33 patients evaluated, 16 had chest pain suggestive of CAD and 17 were asymptomatic. None had a history of prior myocardial infarction or clinical and echocardiographic signs of heart disease. LBBB appeared at a heart rate ranging from 70 to 160 b.min-1. Eighteen patients showed repolarization abnormalities (ST segment depression with deep inverted T waves) compatible with ischaemia, after QRS normalization. Thallium-201 myocardial uptake was normal in 12 subjects; in the remaining 21, reversible Thallium-201 defects were demonstrated in the septum (18 patients), septum and apex (2), and septum and infero-apical wall (1). No patient had irreversible defects and all had normal coronary angiography, with negative ergonovine tests for coronary artery spasm. The patients were followed up for a mean of 43 months (range 16-80). One patient died from sudden death, but no cardiac event occurred in the other patients. In conclusion, exercise Thallium-201 myocardial scintigraphy showed a high prevalence (64%) of reversible perfusion defects in a group of patients with exercise-induced LBBB without any evidence of CAD at angiography or coronary spasm at ergonovine test. Moreover, follow-up showed a relatively low rate of major cardiac events.

Rate-related left bundle branch block as a cause of non-ischemic chest pain

A case is presented of rate-dependent left bundle branch block associated with chest pain in a patient with angiographically normal coronary arteries. Lactate extraction showed no evidence of myocardial ischemia. It appears that in this case, chest pain was associated with sudden ventricular asynergy rather than myocardial ischemia.

Four-year follow-up study in patients with angina pectoris and normal coronary arteriograms ("syndrome X")

In patients with typical stress-induced anginal pain, normal coronary arteries, and unimpaired left ventricular performance at rest ("syndrome X"), a reduced coronary dilatory capacity, abnormal lactate metabolism during stress, and reduction of left ventricular functional reserve have been described. A group of 40 patients with syndrome X was followed for several years to determine their long-term prognosis. In 27 patients pulmonary artery pressure and in 19 patients left ventricular ejection fraction were reassessed during rest and exercise approximately 4 years after the initial examination. In patients with stress-induced ST-segment depression, these variables did not change during the observation period. In patients with constant or rate-dependent left bundle branch block, however, there was significant deterioration of left ventricular performance during rest (pulmonary artery mean pressure, 16 +/- 3 vs. 17 +/- 4 mm Hg, p = NS; left ventricular ejection fraction, 62 +/- 5% vs. 55 +/- 5%, p less than 0.05) and exercise (pulmonary artery, 30 +/- 6 vs. 39 +/- 10 mm Hg, p less than 0.005; left ventricular ejection fraction, 59 +/- 6% vs. 49 +/- 5%, p less than 0.01). These findings suggest that in syndrome X two subgroups with distinctly different prognoses may be defined: In patients with stress-induced ST-segment depression during exercise, left ventricular performance remains well preserved; however, in patients with either constant or rate-dependent left bundle branch block, there is significant deterioration of left ventricular function within several years.

Chest Pain and Rate-Dependent Left Bundle Branch Block in Patients with Normal Coronary Arteriograms

A triad of exertional chest discomfort, transient rate-dependent left bundle branch block (LBBB), and normal coronary arteries is presented in seven consecutive patients. Although the clinical symptoms resembled effort angina, qualities atypical of classic angina pectoris were commonly noted: 1) the onset was always abrupt; and 2) the pain was local, never radiating; 3) palpitation; and 4) "walk through" phenomenon were often present. The abrupt pain took place simultaneously with the appearance of LBBB induced by physical exercise in all seven patients. Atrial pacing or spontaneous resting heart rate changes produced similar sensations and LBBB in four of the five patients examined in this way. Similarly, in the same four patients kinetocardiographic recordings disclosed a sudden occurrence of paradoxic cardiac movement at the moment LBBB and chest pain appeared. The paradoxic systolic motion disappeared at reversion to normal conduction.

Effect of intermittent left bundle branch block on left ventricular performance in the normal heart

The effect of left bundle branch block on left ventricular performance was studied in a patient with rate-dependent left bundle branch block and an otherwise normal heart. The timing of left heart events, hemodynamic pressures and indexes of left ventricular contractility were determined during normal intraventricular conduction and during left bundle branch block. The results indicate that in the normal heart left bundle branch block has no significant effect on left ventricular performance.

Transient unifascicular, bifascicular and trifascicular block: Electrophysiologic correlations in a patient with rate-dependent left bundle branch block and transient right bundle branch block

Correlations of the His to ventricular (H-V) conduction time were made with the surface electrocardiogram during normal intraventricular conduction, unifascicular block (right bundle branch block), bifascicular block (left bundle branch block) and trifascicular block (right and left bundle branch block) in a patient with rate-dependent left bundle branch block who had transient right bundle branch block during recording of the His bundle electrogram. The results provide a functional confirmation of the theory that a prolonged H-V time is a manifestation of trifascicular disease.