Transient Bundle Branch Block Research Articles

Transient bundle branch block during the perioperative period-A meta-summary of case reports.

Transient bundle branch block during the perioperative period-A meta-summary of case reports.

A case of transient bundle branch block in abdominal aorta and renal artery thrombosis

Aortic thrombosis with simultaneous thrombosis of the renal arteries is rare.

Transient right bundle branch block in a patient with acute pulmonary embolism

We report the case of an 86-year-old man found at home with acute chest pain and dyspnea. He presented some episodes of left chest pain combined with dyspnea. The physical examination revealed crackling sounds on the bases of the lungs without other anomalies. Electrocardiograms revealed a transient and complete right bundle branch block with inverted T waves in leads V1, V2, and V3. He was diagnosed with a proximal bilateral acute pulmonary embolism without acute cor pulmonale. We describe a case of a transient bundle branch block, without tachycardia or acute cor pulmonale, revealing a pulmonary embolism.

Relation of New Permanent Right or Left Bundle Branch Block on Short- and Long-Term Mortality in Acute Myocardial Infarction Bundle Branch Block and Myocardial Infarction

The aim of this study was to investigate the prognosis associated with bundle branch block (BBB) depending on location, time of appearance, and duration in patients with myocardial infarction (MI). From January 1998 to January 2008, we recruited 5,570 patients with acute MI. Thirty-day and 7-year all-cause mortality, according to BBB location, time of appearance, and duration were analyzed by multivariable analyses. BBB was present in 964 patients (17.3%); right BBB (RBBB) 10.6% and left BBB (LBBB) 6.7%. Overall mortality rate at 30 days was 13.2% (n= 738) and 7 years was 6.34 deaths per 100 patient-year. Both RBBB and LBBB were more frequently previous, 42.9% and 58.8%. Compared with non-BBB, all BBB groups showed higher prevalence of co-morbidities, especially rates of diabetes (49.0% vs 34.3%, p <0.001) and more often heart failure during hospitalization (54.5% vs 26.6%, p <0.001). Compared with RBBB, patients with LBBB had a higher prevalence of co-morbidities and a higher mortality, especially the new BBB, 30 days: 52.5% versus 31.6% and 7 years (incident rate): 27.2 versus 13.3 per 100 patient-year. New transient BBB had lower heart failure on admission (42.6% vs 58.3%, p= 0.008) and 30-day mortality (20.3% vs 69.6%, p <0.001) compared with permanent in both locations. New permanent RBBB was independently associated with 30-day (hazard ratio [HR] 2.01, 95% confidence interval [CI] 1.45 to 2.79) and 7-year mortality (HR 3.12, 95% CI 2.38 to 4.09). New-permanent LBBB was independently associated with 30-day (HR 2.15, 95% CI 1.47 to 3.15) and 7-year mortality (HR 2.91, 95% CI 2.08 to 4.08). In conclusion, in patients with acute MI, the appearance of a new BBB was independently associated with a higher 30-day and 7-year all-cause mortality.

Unusual presentationof rate-dependent intermittent transient bundle branch block in a patient with head injury

Unusual presentationof rate-dependent intermittent transient bundle branch block in a patient with head injury

Long-Term Follow-Up of Idiopathic Ventricular Fibrillation Ablation: A Multicenter Study

This multicenter study sought to evaluate the long-term follow-up of patients ablated for idiopathic ventricular fibrillation (VF). Catheter ablation of idiopathic VF that targets ventricular premature beat (VPB) triggers has been shown to prevent VF recurrences on short-term follow-up. From January 2000, 38 consecutive patients from 6 different centers underwent ablation of primary idiopathic VF initiated by short coupled VPB. All patients had experienced at least 1 documented VF, with 87% having experienced ≥2 VF episodes in the preceding year. Catheter ablation was guided by activation mapping of VPBs or pace mapping during sinus rhythm. There were 38 patients (21 men) age 42 ± 13 years, refractory to a median of 2 antiarrhythmic drugs. Triggering VPBs originated from the right (n = 16), the left (n = 14), or both (n = 3) Purkinje systems and from the myocardium (n = 5). During a median post-procedural follow-up of 63 months, 7 (18%) of 38 patients experienced VF recurrence at a median of 4 months. Five of these 7 patients underwent repeat ablation without VF recurrence. Survival free of VF was predicted only by transient bundle-branch block in the originating ventricle during the electrophysiological study (p < 0.0001). The number of significant events (confirmed VF or aborted sudden death) was reduced from 4 (interquartile range 3 to 9) before to 0 (interquartile range 0 to 4) after ablation (p = 0.01). Ablation for idiopathic VF that targets short coupled VPB triggers is associated with a long-term freedom from VF recurrence.

Vector electrocardiographic alterations after percutaneous septal ablation in obstructive hypertrophic cardiomyopathy. Possible anatomic causes.

Analyze the dromotropic disturbances (vector-electrocardiographic), and the possible anatomic causes, provoked by selective alcohol injection in the septal branch, for percutaneous treatment, of obstructive hypertrophic cardiomyopathy. Ten patients with a mean age of 52.7 years underwent percutaneous septal ablation (PTSA) from october 1998; all in functional class III/IV). Twelve-lead electrocardiogram was performed prior to and during PTSA, and later electrocardiogram and vectorcardiogram according to Frank's method. The patients were followed up for 32 months. On electrocardiogram (ECG) prior to PTSA all patients had sinus rhythm and left atrial enlargement, 8 left ventricular hypertrophy of systolic pattern. On ECG immediately after PTSA, 8 had complete right bundle-branch block; 1 transient total atrioventricular block; 1 alternating transient bundle-branch block either right or hemiblock. On late ECG 8 had complete right bundle-branch block confirmed by vectorcardiogram, type 1 or Grishman. Septal fibrosis following alcohol injection caused a predominance of complete right bundle-branch block, different from surgery of myotomy/myectomy.

Bundle branch block as a predictor of long-term survival after acute myocardial infarction

Using a community-based population of patients with acute myocardial infarction (AMI), we sought to: (1) determine the prevalence of bundle branch block (BBB) on the presenting electrocardiogram (ECG), (2) compare the clinical characteristics and the treatment administered to patients with and without BBB, and (3) determine the association of BBB with mortality. We analyzed the admission ECGs of 894 consecutive patients with AMI from Olmsted County, Minnesota, seen at our institution from January 1988 to March 1998. Of these, 53 had left BBB (LBBB) (5.9%) and 60 had right BBB (RBBB) (6.7%). Patients with BBB were more likely to be older, have a history of AMI or hypertension, and to be in Killip class >I at presentation. They were less likely to receive primary reperfusion therapy, β blockers, or heparin, but more likely to receive angiotensin-converting enzyme inhibitors. They had lower mean predischarge ejection fractions (38 ± 16% vs 50 ± 15%, p <0.0001). In-hospital mortality was 13.3%, 17.0%, and 9.1% for patients with RBBB, LBBB, and no BBB, respectively (p = 0.11). Respective postdischarge survival at 1, 3, and 5 years was 80%, 60%, and 50% in the RBBB group, 78%, 56%, and 51% in the LBBB group, and 92%, 85%, and 76% in the group without BBB (p <0.0001). Although BBB was not an independent predictor of mortality on multivariate analysis, the presence of transient or persistent BBB with AMI is an easily recognized clinical marker of increased mortality. Our conclusion from this study is that in a community-based population, patients who had LBBB or RBBB at the time of AMI had lower predischarge ejection fractions and higher in-hospital and long-term unadjusted mortality.

Effects of Intracavitary Blood Flow and Electrode–Target Distance on Radiofrequency Power Required for Transient Conduction Block in a Langendorff-Perfused Canine Model

Objectives. We sought to quantify the effects of electrode–target distance and intracavitary blood flow on radiofrequency (RF) power required to induce transient conduction block, using a Langendorff-perfused canine ablation model.Background. Given the thermally mediated nature of RF catheter ablation, cooling effects of intracavitary blood flow and electrode–target distance will influence lesion extension and geometry and electrophysiologic effects.Methods. In eight Langendorff-perfused canine hearts, the right ventricular free wall was opened, and the right bundle branch (RBB) carefully localized by multielectrode activation mapping. The right atrium was paced at cycle length of 500 ms. Proximal and distal electrodes were attached at the endocardial aspect of the RBB, and the perfused heart was submerged in heparinized blood at 37°C. A standard 4-mm tip ablation electrode was positioned at a constant contact pressure of 5gbetween the two electrodes at the site of maximal RBB potential (0 mm) and 2 and 4 mm distant from this site along a line perpendicular to the RBB. RF pulses (500 kHz) were delivered for 30s at 0.5-W increments until transient bundle branch block. In four hearts, intracavitary flow was simulated by directing a 30-cm/s jet of blood parallel to the septum at the ablation site, and the protocol was repeated to assess the effects on power required for block. In one heart, the effect of variable flow was assessed (0, 15 and 30 cm/s).Results. An exponential distance-related increase was seen in power required for block, from 1.8 ± 0.9 W (mean ± SD) at 0 mm to 5.4 ± 1.1 W at 4 mm. In the presence of 30-cm/s flow, an increase to 3.9 ± 0.8 W at 0 mm and 13.1 ± 2.4 W at 2 mm was seen. At 4 mm, coagulum formation invariably occurred before block could be induced. For 15-cm/s flow, less power was required: 3 and 7 W at 0 and 2 mm, respectively.Conclusions. Increasing the ablation electrode–target distance causes an exponential increase in power required for conduction block; this relation is profoundly influenced by intracavitary flow. Given the geometry of endomyocardial RF lesions, these findings are particularly relevant for directly subendocardial ablation targets.

Comparison of transesophageal and intracardiac electrophysiologic studies in characterization of supraventricular tachycardia in pediatric patients

This study sought to determine the accuracy of transesophageal electrophysiologic studies in diagnosing and characterizing various mechanisms of supraventricular tachycardia in pediatric patients. Transesophageal electrophysiologic studies are a relatively noninvasive means of characterizing supraventricular tachycardia. Although widely used, to our knowledge no data exist that directly compare information obtained from transesophageal electrophysiologic studies with that from intracardiac electrophysiologic studies. We reviewed the records of 57 pediatric patients undergoing both transesophageal and intracardiac electrophysiologic studies at our institution. The results of these studies were compared with respect to mechanism of tachycardia, localization of accessory atrioventricular (AV) connections (if present) and characterization of anterograde accessory connection conduction properties. Tachycardia mechanisms were concordant in 56 of 57 patients: orthodromic reciprocating tachycardia in 43, antidromic reciprocating tachycardia in 1, both orthodromic and antidromic tachycardia in 2, AV node reentrant tachycardia in 5, atrial reentrant tachycardia in 4 and ectopic atrial tachycardia in 2. Of 29 patients with orthodromic reciprocating tachycardia using a concealed accessory connection, transesophageal study predicted the accessory connection site through changes induced by transient bundle branch block in 12. By the Bland-Altman method in 14 patients with pre-excitation, the anterograde accessory connection effective refractory period determined by transesophageal study compared favorably with that determined by intracardiac study (mean difference 5.0 ms, limits of agreement -55 and 65 ms). Transesophageal electrophysiologic studies are a highly accurate means of diagnosing and characterizing various mechanisms of supraventricular tachycardia in pediatric patients.

790-6 The Incidence and Clinical Relevance of Bundle Branch Block in Patients with Acute Myocardial Infarction Treated with Thrombolytic Agents

In the pre-thrombolytic era the occurrence of new bundle branch block in the setting of acute myocardial infarction ranged between 6 to 12%. Whether thrombolytic therapy alter the incidence and clinical relevance of bundle branch block during acute myocardial infarction is unclear. In 324 consecutive patients with acute myocardial infarction admitted under the Gusto I protocol the incidence of new onset bundle branch block (BBB) was examined with respect to the infarct related artery (IRA). Each patient underwent continuous 12 lead ECG rnonitoring for a period of 24 – 72 hours using a system which stored any ST change persisting for more than 60 seconds. Of the 324 patients, the overall incidence of BBB was found to be 28% (n = 91), transient BBB was seen in 24.3% (n = 79) of patients, persistent BBB in 3.7% (n = 12) and alternating right and left BBB in 2.2% (n = 7). When examined with respect to the infarct related artery, patients with LAD infarcts had a higher incidence of BBB as compared to those with infarcts in the RCA/Circumflex distribution (LAD 39% vs. RCA 26% and Circumflex 15.6%, p &lt; 0.05). The occurrence of right or left BBB was not predicted based on the infarct related artery, being equally distributed in patients with LAD/RCA infarcts. Mortality in the overall population was 5% (n = 16). Persistent BBB, irrespective of the infarct related artery, was predictive of a higher mortality (33% = 4/12) than transient (5% = 4/79), or no BBB (3.4% = 8/233) (p &lt; 0.01). 1) In this population, the occurrence of persistent BBB is lower than previously reported. Whether this is secondary to the use of thrombolytic agents requires further evaluation. 2) LAD occlusion is associated with a higher incidence of BBB. 3) The occurrence of either right or left 8BB was not predicted by the occluded artery. 4) Persistent BBB predicts a worse prognosis.

Effects of free wall ischemia and bundle branch block on systolic ventricular interaction in dog hearts

Systolic direct ventricular interaction is thought to occur via the ventricular septum and the coordinated contraction of common fibers shared by both ventricles. The purpose of the present study was to evaluate the effects of transient free wall ischemia and bundle branch block, which disrupt the coordinated contraction of shared common fibers, on left-to-right systolic ventricular interaction. We produced transient right and left ventricular free wall ischemia by 2-min coronary artery occlusions and bundle branch block by ventricular pacing in nine in situ dog hearts. To eliminate any confounding effect of series interaction, we used an abrupt hemodynamic perturbation (aortic constriction), and we measured systolic interaction gain (IG) as delta right ventricular peak systolic pressure/delta left ventricular peak systolic pressure (IG(peak)) and instantaneous delta right ventricular pressure/delta left ventricular pressure at matched data sampling times (IG(inst)), along with changes in right ventricular stroke volume and stroke work before and on the beat immediately after the aortic constriction. To achieve equivalence of the interventricular septal pressure transmission contribution to ventricular interaction, the delta left ventricular peak systolic pressure produced by the aortic constriction was matched under all experimental conditions [average increase: 64 +/- 19 (SD) mmHg]. Control IG(peak) was 0.12 +/- 0.05, and control IG(inst) was 0.11 +/- 0.05. These values did not change with either free wall ischemia or ventricular pacing, with or without an intact pericardium. The changes in right ventricular stroke volume and stroke work produced by the aortic constriction were not different from zero, during either ischemia or ventricular pacing, with or without an intact pericardium.(ABSTRACT TRUNCATED AT 250 WORDS)

New bundle branch block after coronary artery bypass grafting— evaluation by CK-MB isoenzyme analysis and transoesophageal echocardiography

Twelve patients with a new complete bundle branch block after coronary artery bypass grafting underwent transoesophageal echocardiography (TEE). The results of TEE were compared with the pre-operative ventriculography, CK-MB isoenzyme time-release curves and clinical course. In eight patients with transient right bundle branch block or bifascicular block, low CK-MB activities and an uncomplicated postoperative course, transoesophageal echocardiography showed no new segmental wall motion abnormalities apart from a paradoxical septal movement in five. A persistent right or left bundle branch block was associated with either elevated isoenzyme activities, transoesophageal echocardiographic evidence of new segmental wall motion disturbance or both in four patients. One patient died because of fatal arrhythmia and one suffered from a prolonged low cardiac output syndrome. A transient bundle branch block is usually a benign electrocardiographic finding. In case of a persistent bundle branch block associated with elevated CK MB isoenzymes, new left ventricular wall motion disturbances indicating a peri-operative myocardial injury are easily detected by transoesophageal echocardiography.

Short- and long-term prognostic importance of complete bundle-branch block complicating acute myocardial infarction.

Among 1013 consecutive patients with acute myocardial infarction (AMI), 104 (10%) developed complete bundle-branch block (BBB). The clinical characteristics and the short- and long-term prognosis were similar in the 53 patients with right and the 51 patients with left BBB. Compared to the 909 patients without this conduction disturbance, these 104 patients were older (64 +/- 9 vs. 58 +/- 10 years, p less than 0.001), more frequently women (26 vs. 17%, p less than 0.05), had a larger infarct (peak CK 1672 +/- 1124 vs. 1356 +/- 1089 IU/l, p less than 0.001), more frequently anterior (60 vs. 37%, p less than 0.001). They had a higher incidence of Killip class greater than 1 (63 vs. 38%, p less than 0.001), pericarditis (40 vs. 23%, p less than 0.001), atrial fibrillation or flutter (22 vs. 12%, p less than 0.01), ventricular fibrillation (15 vs. 9%, p less than 0.05), and atrioventricular block (23 vs. 11%, p less than 0.001). Both hospital mortality (32 vs 10%, p less than 0.001) and 3-year posthospital mortality (37 vs. 18%, p less than 0.001) were much higher among patients with complete BBB. Transient BBB had the same deleterious prognosis as BBB persistent at discharge (mortality 33 vs. 39%, NS). The prognostic importance of BBB was more prominent during the first 6 months after infarction (mortality between 6 and 36 months: 18% with BBB vs. 11% without BBB, NS).

Cardiovascular Collapse in Infants: Association With Paroxysmal Atrial Tachycardia

Four infants, aged 16 to 28 days (mean 23 days), were seen in the emergency room with acute cardiovascular collapse and with normal heart rate and rhythm. During evaluation for cardiovascular collapse, no infant had sepsis; cardiac assessment revealed normal intracardiac anatomy but global cardiac chamber enlargement and poor left ventricular systolic function, which resolved with supportive treatment. However, three of the four infants demonstrated ventricular preexcitation on their surface electrocardiogram and, subsequently, two infants had transient episodes of tachycardia. During a transesophageal pacing study to evaluate inducibility and electrophysiologic characteristics of tachycardia, sustained tachycardia was initiated in all four infants. Reentrant tachycardia used an accessory atrioventricular connection as evidenced by the presence of preexcitation during sinus rhythm (three infants), the ability to initiate and terminate tachycardia by programmed electrical stimulation (four infants), minimum ventriculoatrial interval recorded in the esophagus (V-Aeso) exceeded 70 ms (four infants), transient bundle branch block during tachycardia prolonged the cycle length and the V-Aeso by 30 to 50 ms (three infants). Findings in these infants suggested prior episodes of prolonged tachycardia as the probable etiology of the cardiovascular collapse.

Differentiation of septal from free wall accessory pathway location: Observations during bundle branch block in reciprocating tachycardia in the presence of type I antiarrhythmic drugs

In patients with Wolff-Parkinson-White syndrome, observations during bundle branch block (BBB) in reciprocating tachycardia are of value in accessory pathway localization. Most importantly, an increase in the ventriculoatrial (VA) Interval of ≥ 35 ms has indicated an ipsilateral free wall location and excluded a septal location. The present study examined whether data collected in the presence of type I antiarrhythmic drugs retained localizing value. Review of retrospective data showed that observations in the drug-free state were precluded by the need to suppress atrial arrhythmia during electrophysiologic study in 20% of patients with Wolff-Parkinson-White syndrome who underwent preoperative workup. Prospectively, in 15 patients with left free wall or posteroseptal pathways, we observed transient left BBB during tachycardia before and after administration of procainamide, disopyramide or quinidine. Serum drug levels ranged from 4.6 to 6.9 mg/liter, except in 1 patient with a serum procainamide level of 18 mg/liter. Drugs increased the VA interval during narrow QRS tachycardia by 17% (p < 0.01). However, the change in the VA interval with left BBB was not significantly affected. The baseline and drug values averaged 73 ms (range 39 to 94) and 70 ms (range 39 to 90), respectively, for left free wall pathways (n = 8) and 19 ms (range 0 to 28) and 21 ms (range 2 to 35), respectively, for posteroseptal pathways (n = 7). Among the latter, the interval increased < 30 ms during left BBB except in the patient with the high serum procainamide level, in whom the increase was 35 ms. Thus, the VA interval change that accompanied left BBB remained of localizing value with moderate blood levels of type I drugs and an increase ≥ 35 ms indicated a left free wall rather than posteroseptal pathway.

Transient bundle branch block following use of hypothermic cardioplegia in coronary artery bypass surgery: High incidence without perioperative myocardial infarction

Hypothermic cardioplegia (HCP) is a method commonly used for myocardial preservation at the time of aortic cross-clamping during coronary artery bypass grafting (CABG). This study assessed the frequency and significance of transient bundle branch block (BBB) in 50 patients undergoing CABG using HCP compared to 61 controls. All patients had normal QRS complexes on preoperative ECG. Clinical, hemodynamic, and operative data were similar in both groups. Seventeen (34%) of the HCP group and four (6%) of the controls developed postoperative BBB ( p < 0.001). These changes were transient in all but three patients in the HCP group. None of the HCP patients with transient BBB had evidence of perioperative myocardial infarction. Clinical and operative parameters did not provide prediction of development of transient BBB. This study demonstrates that transient BBB in the immediate post-CABG period occurs commonly with the use of HCP and does not indicate myocardial necrosis.

His bundle recordings in patients with bundle branch block and transient neurologic symptoms.

His bundle electrograms were recorded in 19 patients with bundle branch block (BBB) and transient neurologic symptoms allowing for determination of intra-atrial (P-A), atrioventricular (A-V), nodal (A-H) as well as infranodal conduction (H-Q) times. The patients were initially monitored in a coronary care unit and have been followed for a mean period of 8 ± 4 months. In six patients (Group I) neurologic symptoms were observed in the absence of electrocardiographic evidence of A-V block. In six patients (Group II) the cause of symptoms was uncertain; two of these patients had relief of symptoms after permanent cardiac pacemaker insertion and were presumed to have episodic high grade A-V block. In seven subjects (Group III) complete A-V block was documented as the cause of the symptoms; these patients were studied when 1:1 antegrade A-V conduction returned. There was no significant difference between mean P-A, A-H, and QRS durations among the patients in the three groups. Mean H-Q (89 ± 20 msec) for Group III was significantly longer than that for Group I (56 ± 9 msec) or Group 11 (64 ± 11 msec) ( P &lt; .001). All patients with presumed or documented episodes of high grade A-V block had abnormal H-Q intervals, and six of the nine patients with presumed or documented complete A-V block had H-Q intervals &gt;80 msec. The present data suggest that patients with transient neurologic symptoms, bifascicular or left BBB associated with marked prolongation of H-Q (≧80 msec), should be seriously considered as candidates for insertion of a permanent cardiac pacemaker even in the absence of documented high grade or completeA-V block.

Diagnosis of Transient Bundle Branch Block Using Timed Vectorcardiography

Numerous electrocardiographic, clinical and pathologic studies support the concept of a trifascicular bundle branch system in man. 1 Rosenbaum MB Elizari MV Lazzari JO Los Hemibloqueos. Buenos Aires, Paidos1968 Google Scholar , 2 Lev M Anatomic basis for atrioventricular block. Am J Med. 1964; 37: 742-748 Abstract Full Text PDF PubMed Scopus (226) Google Scholar , 3 Lenegre J Etiology and pathology of bilateral bundle branch block in relation to complete heart block. Progr Cardiov Dis. 1964; 6: 409-444 Abstract Full Text PDF PubMed Scopus (254) Google Scholar Vectorcardiographic criteria have been formulated for the diagnosis of left anterior hemiblock, 4 Benchimol A Barreto EC Pedraza A et al. The Frank vectorcardiogram in left anterior hemiblock. J Electrocardiol. 1971; 4: 116-128 Abstract Full Text PDF PubMed Scopus (19) Google Scholar left posterior hemiblock 5 Benchimol A Desser KB Massey BJ The Frank vectorcardiogram in left posterior hemiblock. J Electrocardiol. 1971; 4: 129-136 Abstract Full Text PDF PubMed Scopus (12) Google Scholar and the combination of left anterior hemiblock and right bundle branch block. 6 Kulbertus H Collignon P Humblet L Vectorcardiographic study of QRS loop in patients with left superior axis deviation and right bundle-branch block. Br Heart J. 1970; 32: 386-392 Crossref PubMed Scopus (13) Google Scholar , 7 Benchimol A Desser KB Barreto EC et al. Vectorcardiographic features of left anterior hemiblock combined with complete right bundle branch block. J Electrocardiol. 1971; 4: 322-330 Abstract Full Text PDF PubMed Scopus (5) Google Scholar The development of techniques for recording timed vectorcardiograms 8 Selvester RH Haywood LJ Griggs DE The timed vectorcardiogram: a useful clinical tool (as applied to the study of 1,500 subjects). Dis Chest. 1965; 47: 170-178 Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar , 9 Benchimol A Pedraza A The timed Frank vectorcardiogram in the diagnosis of cardiac arrhythmias. J Electrocardiol. 1969; 2: 363-372 Abstract Full Text PDF PubMed Scopus (15) Google Scholar has recently afforded an opportunity to record the vectorcardiographic manifestations of transient fascicular blocks in both single and biplane modes. We describe here the graphic recordings from two patients with intermittent bundle branch block which exemplify the use of the timed Frank vectorcardiogram (running loop) for the graphic display of such conduction disturbances.

Transient Bundle Branch Block Occurring During Anesthesia

Transient Bundle Branch Block Occurring During Anesthesia