Prospective Study of the Clinical Features and Outcomes of Emergency Department Patients with Delayed Diagnosis of Pulmonary Embolism

Objectives: The authors hypothesized that emergency department (ED) patients with a delayed diagnosis of pulmonary embolism (PE) will have a higher frequency of altered mental status, older age, comorbidity, and worsened outcomes compared with patients who have PE diagnosed by tests ordered in the ED.
Methods: For 144 weeks, all patients with PE diagnosed by computed tomographic angiography were prospectively screened to identify ED diagnosis (testing ordered from the ED) versus delayed diagnosis (less than 48 hours postadmission). Serum troponin I level, right ventricular hypokinesis on echocardiography, and percentage pulmonary vascular occlusion were measured at diagnosis; patients were prospectively followed up for adverse events (death, intubation, or circulatory shock).
Results: Among 161 patients with PE, 141 (88%) were ED diagnosed and 20 (12%) had a delayed diagnosis. Patients with a delayed diagnosis were older than ED-diagnosed patients (61 [±15] vs. 51 [±17] years; p < 0.001), had a longer median time to heparin administration (33 vs. 8 hours; p < 0.001), and had a higher frequency of altered mental status (30% vs. 8%; p = 0.01) but did not have a higher frequency of prior cardiopulmonary disease (25% vs. 23%). Patients with a delayed diagnosis had equal or worse measures of PE severity (right ventricular hypokinesis on echocardiography, 60% vs. 58%; abnormal troponin I level, 55% vs. 24%); on computed tomographic angiography, ten of 20 patients with a delayed diagnosis had PE in lobar or larger arteries and >50% vascular obstruction. Patients with a delayed diagnosis had a higher rate of in-hospital adverse events (9% vs. 30%; p = 0.01).
Conclusions: In this single-center study, the diagnosis of PE was frequently delayed and outcomes of patients with delayed diagnosis were worse than those of patients with PE diagnosed in the ED.     

Excitation of the intrinsic conduction system through his and interventricular septal pacing

BACKGROUND: Direct His bundle pacing results in rapid synchronous ventricular activation. However, clinical experiences with such pacing have been associated with long procedure times and compromised pacing and sensing performance. METHODS: We evaluated myocardial activation sequences (AS) for pacing of the His bundle and peri-His region and assessed acute pacing performance using custom-designed plunge electrodes. Unipolar pacing was performed in isolated swine hearts (n = 10) using four quadripolar stimulation/sensing electrodes implanted into the interventricular septum and equally spaced between the membranous septum and the coronary sinus ostium (zones 1-4, respectively; electrode depth (ED) 1 = most distal, ED 4 = most proximal). Optimal pacing sites were defined as: pacing thresholds < or = 1.5 V, a P-R ratio of < or = 0.5, and > or = 50% occurrence of an intrinsic midseptal left ventricular (LV) endocardial electrical breakout (BO) and activation pattern. RESULTS: Pacing thresholds improved with greater depth of electrode location within the septum (ED 1: 1.51 +/- 0.8 V vs ED 4: 5.2 +/- 3.8 V, P < 0.001), as did the P-R ratio (0.34 +/- 0.6 vs 0.78 +/- 1.0, P < 0.05). His potentials were only observed in zone 1 and 2 electrodes (0.12 and 0.02 mV, respectively). Only electrodes in zones 1 and 2 produced LV endocardial electrical BOs in the midseptal region that demonstrated an intrinsic-like endocardial AS. Depth 1 and 2 electrodes (11.75 and 8.75 mm, respectively) in zone 1 satisfied all three optimal pacing site requirements. CONCLUSIONS: This study has shown that LV activation patterns similar to sinus rhythm may be achieved without direct activation of the His bundle, while maintaining acceptable pacing and sensing performance. These data indicate that pacing systems designed to stimulate the tissues below the point at which the His bundle penetrates the central fibrous body may provide improved system efficiency and LV performance in comparison to both direct His bundle pacing and traditional pacing sites.     

High Energy Transcatheter Cardioversion for Chronic, Poorly Tolerated Atrial Fibrillation

Between August 1991 and May 1993, 14 patients affected by chronic, poorly tolerated atrial fibrillation (AF) were submitted to high energy transcatheter Cardioversion. Mean duration of AF was 27.4 ± 45.1 months. In nine patients (56%), AF lasted for > 1 year. All patients had underlying heart disease, with a mean LVEF of 45.2%± 11.8% and a NYHA Class ≥ II. Previously, a mean of 2.9 ± 1.3 patients failed external electrical Cardioversion, with and without antiarrhythmics, have been attempted. Transcatheter conversion was performed by pulling the His-bundle catheter back in the right atrial cavity until no His bundle activity was recorded on distal poles, and then delivering the shock between a proximal electrode (cathode) and a back plate (anode). In all patients, transcatheter conversion restored sinus rhythm. Transient complete atrioventricular (AV) block was observed in four patients (28%), and treated by prophylactic temporary pacing. At 1 year, seven patients (50%) were still in sinus rhythm. In this series, only younger age could be related to AF recurrence (46.1 ± 10.8 vs 63.4 ± 6.8 years, P ≤ 0.004), even if prophylaxis with amiodarone showed a positive trend versus sinus rhythm maintenance (71 % vs 14%, P = NS). In conclusion, high energy transcatheter Cardioversion is a safe and effective method of restoring sinus rhythm in patients with chronic, poorly tolerated AF. In these patients, high energy transcatheter Cardioversion could be considered as an alternative to AV node ablation techniques, avoiding pacemaker implant and embolic risk. Larger studies are needed to determine better patient selection and delineate drug strategy after the procedure.     

The Probability of Pulmonary Embolism Is a Function of the Diagnoses Considered Most Likely Before Testing

Objectives: To determine the frequency of pulmonary embolism (PE) diagnosis when different alternative diagnoses were considered most likely before testing, because the relationship between specific alternative diagnoses and the diagnosis of PE has not been explored.
Methods: This study was a preplanned secondary analysis of a prospective study of the diagnosis of pulmonary embolism conducted in the emergency department (ED) of an urban university hospital. Physicians were queried as to their most likely pretest diagnosis when they ordered any of the following tests to evaluate possible PE: D-dimer, contrast-enhanced computed tomography of the chest, ventilation–perfusion lung scan, or pulmonary angiogram. To compare the frequency of PE diagnosis across alternative diagnoses, risk ratios, 95% confidence intervals (CI), and p-values using Fisher's exact test were calculated.
Results: Six hundred seven patients were enrolled, and 61 had PE. Physicians thought PE was the most likely pretest diagnosis in 162 (26.7%) patients, and 20.4% (95% CI = 14.4% to 27.4%) of these patients had PE. For four alternative diagnoses, PE was diagnosed less frequently than when PE was considered most likely: musculoskeletal pain (2.2%, 95% CI = 0.4% to 6.2%), anxiety (1.7%, 95% CI = 0.0 to 9.2%), asthma or chronic obstructive pulmonary disease (0, 95% CI = 0.0 to 10.9%), and viral syndrome (0, 95% CI = 0.0 to 14.3%).
Conclusions: The frequency of PE is related to the most likely pretest alternative diagnosis. PE is diagnosed infrequently when anxiety, asthma or chronic obstructive pulmonary disease, musculoskeletal pain, or viral syndrome is the most likely alternative diagnosis.     

Is the Fascicle of Left Bundle Branch Involved in the Reentrant Circuit of Verapamil‐Sensitive Idiopathic Left Ventricular Tachycardia?

The exact reentrant circuit of the verapamil-sensitive idiopathic left VT with a RBBB configuration remains unclear. Furthermore, if the fascicle of left bundle branch is involved in the reentrant circuit has not been well studied. Forty-nine patients with verapamil-sensitive idiopathic left VT underwent electrophysiological study and RF catheter ablation. Group I included 11 patients (10 men, 1 woman; mean age 25 +/- 8 years) with left anterior fascicular block (4 patients), or left posterior fascicular block (7 patients) during sinus rhythm. Group II included 38 patients (29 men, 9 women; mean age 35 +/- 16 years) without fascicular block during sinus rhythm. Duration of QRS complex during sinus rhythm before RF catheter ablation in group I patients was significant longer than that of group II patients (104 +/- 12 vs 95 +/- 11 ms, respectively, P=0.02). Duration of QRS complex during VT was similar between group I and group II patients (141 +/- 13 vs 140 +/- 14 ms, respectively, P=0.78). Transitional zones of QRS complexes in the precordial leads during VT were similar between group I and group II patients. After ablation, the QRS duration did not prolong in group I or group II patients (104 +/- 11 vs 95 +/- 10 ms, P=0.02); fascicular block did not occur in group II patients. Duration and transitional zone of QRS complex during VT were similar between the two groups, and new fascicular block did not occur after ablation. These findings suggest the fascicle of left bundle branch may be not involved in the antegrade limb of reentry circuit in idiopathic left VT.     

Noninvasive Arrhythmia Risk Stratification in Idiopathic Dilated Cardiomyopathy: Design and First Results of the Marburg Cardiomyopathy Study

The Marburg Cardiomyopathy Study (MACAS) is a prospective, observational study designed to determine the value of the following potential noninvasive arrhythmia risk predictors in at least 200 patients with idiopathic dilated Cardiomyopathy (IDC) over a 5-year follow-up period: NYHA-class, left ventricular ejection fraction (LVEF), left ventricular end-diastolic diameter, left bundle branch block and atrial fibrillation on ECG, QT/JT dispersion on 12-lead ECG, signal-averaged ECG, ventricular arrhythmias and heart rate variability (HRV) on 24-hour Hotter ECG, baroreflex sensitivity, and microvolt T wave alternans during exercise. This article describes the findings among the first 159 patients with IDCs enrolled in MACAS until May 1998 (40 women, 119 men;age:49 ± 12 years; LVEF: 32 ± 10%). Twenty-nine patients (18%) had atrial fibrillation and 130 patients (82%) were in sinus rhythm. Patients with sinus rhythm were further stratified according to LVEF < 30% (n = 54) versus LVEF ≥ 50% (n = 76). Compared to patients with LVEF ≥ 30%, patients with LVEF < 30% more often had left bundle branch block (43% vs 25%, P < 0.05), nonsustained VT (44% vs 22%, P < 0.05), decreased HRV (SDNN: 95 ± 39 vs 128 ± 42 ms, P < 0.01), decreased baroreflex sensitivity (5.6 ± 4 vs 8.3 ± 6 ms/mmHg, P < 0.01), and T wave alternans (59% vs 37%, P < 0.05). The prognostic significance of these findings will be determined by multivariate Cox analysis at the end of a 5-year follow-up. Primary endpoints in MACAS are overall mortality and arrhythmic events (i.e., sustained VT or VF, or sudden cardiac death).     

Genetic variations observed in arterial and venous thromboembolism--relevance for therapy, risk prevention and prognosis.

We undertook genetic and biochemical assays in patients with arterial (n = 146) and venous (n = 199) thromboembolism and survivors of pulmonary embolism (n = 58) to study causation and gene-life style interactions. In the clinical material from North Western Russia, factor V Leiden was found to be a risk factor in venous thrombosis (OR = 3.6), while the methylenetetrahydrofolate reductase (MTHFR) C677T mutation was a significant variable in both venous (p = 0.03) and arterial thrombosis (p = 0.004). Homocysteine levels were determined (n = 84) and hyperhomocysteinemia correlated with the T allele of the MTHFR gene, and with smoking and coffee consumption. Vitamin supplementation reduced homocysteine levels dependent on MTHFR genotype (36% TT, 25% CT, 22% CC). In pulmonary embolism patients, frequency of the -455G/A beta-fibrinogen dimorphism was studied. Carriers of this allele were significantly underrepresented (p < 0.02) among pulmonary embolism survivors (34.5%) compared to controls (56.7%). Additionally, -455AA homozygotes were found in 11.7% controls but only 1.7% of pulmonary embolism patients (p = 0.006). In venous and arterial thrombosis cases, MTHFR and homocysteine data led to effective dietary supplementation with a reduced risk of disease progression. Results from the pulmonary embolism study may indicate that screening tests for the -455G/A beta-fibrinogen genetic variation could be of prognostic value, and may point the way for novel anticoagulation strategies.     

Internal low energy cardioversion of atrial fibrillation using a single lead system: comparison of a left and right pulmonary artery catheter approach

Internal cardioversion (ICV) has been demonstrated as an effective and safe method for restoring sinus rhythm in patients with AF. Recently, a new single lead system with a balloon-guided cardioversion catheter was introduced. ICV was performed after advancing a 7.5 Fr catheter flow-directed into the left or right pulmonary artery (PA, distal array, cathode). The proximal array (anode) was placed at the lateral RA wall. Synchronized shocks (3/3 ms biphasic impulse) were applied using a stepwise protocol (0.5, 3, 6, 9, 12, 15 J) until sinus rhythm was restored or maximum energy (15 J) was reached. Sixty-five patients (mean age 58 +/- 13 years) with acute and chronic AF were included. Sinus rhythm could be restored in 59 (91%) patients. Cardioversion success was 93% in the left PA compared to 86% in right PA. DFTs for the left and right PA approaches were 7.1 +/- 4.0 J and 10.2 +/- 4.0 J, respectively (P < 0.0001). It was significantly higher in patients with an AF history > 7 days (7.2 +/- 4.1 J) than for those with a recent onset of AF (5.6 +/- 4.1 J), P = 0.0012. Shock impedance differed for the left and right PA lead configuration (53 +/- 11 vs 49 +/- 13 omega, P < 0.05). A right PA lead configuration is as effective compared to a left PA catheter approach when performing ICV for AF. ICV with a single lead system is safe and cardioversion success is comparable to other internal and external cardioversion techniques. In combination with hemodynamic monitoring, flow-directed nonfluoroscopic catheter positioning is feasible and may serve as a valuable therapeutic and diagnostic tool in intensive care units.     

心电图在急性肺动脉栓塞诊断中的价值

目的 评估心电图对急性肺动脉栓塞(肺栓塞)的诊断价值.方法 回顾性分析43例既往无心肺疾病的急性肺栓塞患者住院首次、溶栓后及出院前系列心电图变化.结果 ①入院时首次心电图:心动过速26例(60.47%),右束支传导阻滞10例(23.26%);V1导联和V1～V2导联、V1～V3导联、V1～V4导联、V1～V5导联、V1～v6导联T波倒置分别为34例(79.70%)、20例(46.52%)、12例(27.91%)、9例(20.93%)、7例(16.28%)和2例(4.65%);SⅠ＞0.1 mV、TⅢ倒置、QⅢ和SⅠQⅢTⅢ分别为23例(53.49%)、21例(48.84%)、27例(62.79%)和20例(46.52%).②溶栓后心电图:心动过速消失20例(76.9%),右束支传导阻滞消失4例(40%),胸前导联T波倒置加深4例,SⅠ变浅、QⅢ减小或消失、TⅢ倒置变浅或直立11例.③出院前心电图:心动过速消失;胸前导联T波直立数增加,ST段回基线,QⅢ进一步减小或消失,TⅢ倒置变浅或直立.结论 急性肺栓塞心电图变化多变,需动态观察并密切结合临床加以识别.     

Cardiac rhythm disturbances in patients with left atrial isomerism

This long-term study sought to determine the clinical implication of defective sinus node and AV conduction tissue in patients with left atrial isomerism (LAI). From 1984 to 1998, a total of 22 patients were identified as LAI. Patient age at the last follow-up ranged from 2 to 276 months (90+/-70 months). Associated cardiac anomalies were interruption of the inferior vena cava (n = 18, 82%), common atrium (n = 9, 41%), AV canal (n = 14, 64%), double-outlet right ventricle (n = 8, 36%), and pulmonary stenosis (n = 15, 68%). Palliative interventions were performed in 16 patients (Fontan-type operation in 4 patients, shunt followed by Fontan-type operation in 2, repair of septal defect in 4, and extracardiac intervention in 6). During the follow-up, over half of the patients (n = 14, 64%) developed bradyarrhythmia (onset age: from 1 to 264 months; median 78 months): junctional rhythm (n = 11), sinus bradycardia (n = 8) (5 patients also had junctional rhythm), and AV block (n = 2, both also had junctional rhythm). The probability free from bradyarrhythmia was 80% and 46% at the age of 2 and 6 years, respectively. None of the bradyarrhythmias were directly related to open-heart surgery. Besides, junctional ectopic tachycardia occurred after Fontan-type operation in three of six patients. In two patients, a Mahaim-like pathway was identified during the electrophysiological study. The patients with LAI had a high probability of developing bradyarrhythmias due to abnormal sinus node function. Varied AV conduction abnormalities may include compromised AV conduction, junctional ectopic tachycardia after Fontan-type operation, and an association of Mahaim-like pathway.     

Management of new-onset atrial fibrillation in the emergency department: is there any predictive factor for early successful cardioversion?

OBJECTIVES: The aim of this retrospective study was to assess the initial management of atrial fibrillation (AF) in the emergency department (ED) and to identify predictive factors of early conversion to sinus rhythm, which could justify a short stay in the ED observation unit (EDOU) instead of longer hospitalization. PATIENTS AND METHODS: All patients with acute AF, either of new onset or recurrent, admitted to our hospital during a 12-month period were included in the study. Hospital records were reviewed retrospectively. The success of conversion to sinus rhythm was recorded in association with a series of clinical and laboratory factors. RESULTS: Sixty-seven patients (39 men and 28 women), with a mean age of 63.6+/-12.2 years, were studied. The most frequent presenting symptom was palpitations (n=40, 59.7%). In forty-two patients (62.7%) the duration of symptoms was less than 48 h. Digoxine was the anti-arrhythmic agent most frequently administered (n=26, 38.8%), followed by amiodarone (n=17, 25.4%). Fifty patients (73.1%) converted to sinus rhythm and for 45 of them conversion took place during their stay in the ED or in the EDOU. Factors associated with early conversion to sinus rhythm were aged younger than 65 years (P=0.021) and symptom duration of less than 48 h (P=0.001). On the other hand, the presence of signs of heart failure was significantly associated with unsuccessful early cardioversion (P=0.001). CONCLUSIONS: The majority of patients admitted with AF of acute onset had early conversion to sinus rhythm. AF in young patients, with a duration of symptoms of less than 48 h and without signs of heart failure can be managed in the EDOU, thus avoiding a longer hospitalization.     

Conversion of atrial fibrillation to sinus rhythm during treatment with intravenous esmolol or diltiazem: a prospective, randomized comparison

Prior studies have suggested that intravenous diltiazem reduces the probability of spontaneous conversion of atrial fibrillation (AF) to sinus rhythm in the electrophysiology laboratory and in patients with postoperative AF. Whether diltiazem exerts the same effect in patients presenting to the emergency department (ED) with spontaneous AF is unclear. Fifty patients presenting to the ED with new-onset or paroxysmal AF and a rapid ventricular rate (>100 beats per minute) were randomly assigned to receive intravenous diltiazem or esmolol during the first 24 hours of presentation. Conversion to sinus rhythm occurred in 10 patients (42%) in the diltiazem group compared with 10 patients (39%) in the esmolol group (P = 1.0). Diltiazem does not decrease the likelihood of spontaneous conversion of AF to sinus rhythm in the ED setting.     

Electrocardiographic manifestations of pulmonary embolism

The electrocardiogram (ECG) may be entirely normal in the patient with pulmonary embolism (P/E); alternatively, any number of rhythm and/or morphologic abnormalities may be observed in such a patient. The abnormal ECG may deviate from the norm with alterations in rhythm, in conduction, in axis of the QRS complex, and in the morphology of the P wave, QRS complex, and ST segment/T wave. The electrocardiographic findings associated with PE are numerous, including arrhythmias (sinus tachycardia, atrial flutter, atrial fibrillation, atrial tachycardia, and atrial premature contractions), nonspecific ST segment/T wave changes, T wave inversions in the right precordial leads, rightward QRS complex axis shift and other axis changes, S1Q3 or S1Q3T3 pattern, right bundle branch block, and acute cor pulomnale. This review focuses on the ECG and the various abnormalities seen in the patient with PE.     

Therapy and outcomes in massive pulmonary embolism from the Emergency Medicine Pulmonary Embolism in the Real World Registry

Study Aim

Clinical guidelines recommend fibrinolysis or embolectomy for acute massive pulmonary embolism (PE) (MPE). However, actual therapy and outcomes of emergency department (ED) patients with MPE have not previously been reported. We characterize the current management of ED patients with MPE in a US registry.

Methods

A prospective, observational, multicenter registry of ED patients with confirmed PE was conducted from 2006 to 2008. Massive PE was defined as PE with an initial systolic blood pressure less than 90 mm Hg. We compared inpatient and 30-day mortality, bleeding complications, and recurrent venous thromboembolism.

Results

Of 1875 patients enrolled, 58 (3.1%) had MPE. There was no difference in frequency of parenteral anticoagulation (98.3% [95% confidence interval {CI}, 90.5-101.6] vs 98.5% [95% CI, 97.9-99.1], P = .902) between patients with and without MPE. Fibrinolytic therapy and embolectomy were infrequently used but were used more in patients with MPE than in patients without MPE (12.1% [95% CI, 3.7-20.5] vs 2.4% [95% CI, 1.7-3.1], P < .001, and 3.4% [95% CI, 0.0-8.1] vs 0.7% [95% CI, 0.3-1.1], P = .022, respectively). Comparison of outcomes revealed higher all-cause inpatient mortality (13.8% [95% CI, 4.9-22.7] vs 3.0% [95% CI, 2.2-3.8], P < .001), higher risk of inpatient bleeding complications (10.3% [95% CI, 2.5-18.1] vs 3.5% [95% CI, 2.7-4.3], P = .007), and a higher 30-day mortality (14.0% [95% CI, 4.4-23.6] vs 1.8% [95% CI, 1.2-2.4], P < .001) for patients with MPE.

Conclusions

In a contemporary registry of ED patients, MPE mortality was 4-fold higher than patients without MPE, yet only 12% of the MPE cohort received fibrinolytic therapy. Variability exists between the treatment of MPE and current recommendations.     

How Many Patients with Dilated Cardiomyopathy May Potentially Benefit from Cardiac Resynchronization Therapy?

GRIMM, W., et al .: How Many Patients with Dilated Cardiomyopathy May Potentially Benefit from Cardiac Resynchronization Therapy? The clinical and electrocardiographic Marburg Cardiomyopathy database was analyzed to identify potential candidates for cardiac resynchronization therapy (CRT) with biventricular or left ventricular pacing among 566 patients with dilated cardiomyopathy (DCM). All of the following restrictive selection criteria were fulfilled by 38 patients (7%): NYHA functional class ≥ 3 (   n = 193   , 34%), left ventricular ejection fraction (LVEF) <30% (n = 238, 42%), sinus rhythm (   n = 437   , 77%), left bundle branch block (LBBB,   n = 142   , 25%), and QRS duration ≥ 150 ms (   n = 136   , 24%). In 78 of the 566 patients (14%) all of the following less restrictive selection criteria were fulfilled: NYHA functional class ≥3 (   n = 193   , 34%), LVEF < 35% in presence of any underlying rhythm (n = 326, 58%), QRS duration ≥ 120 ms with right or left bundle branch block (   n = 223   , 39%). Thus, between 7% and 14% of patients with DCM were candidates for CRT depending on the application of strict versus less restrictive selection criteria.(PACE 2003; 26[Pt. II]:155–157)     

Relationship Between QT Interval Duration and Electrical Induction of Ventricular Tachycardia

The relation of inducible ventricular tachycardia (VT) to QT interval duration of ventricular paced rhythm has not been evaluated. To clarify this relation we measured corrected QT interval duration (QT_C) during sinus rhythm and QT interval duration during ventricular paced rhythm (QT-V) in patients with coronary artery disease without (non-VT group = group B) and with inducible VT (VT group = group A). Duration of QT-V was greater in the VT group (n = 20) compared with non-VT group (n = 20) during ventricular pacing at cycle lengths of 600 ms (424 ± 26 vs 396 ± 19 ms, P < 0.01), of 500 ms (407 ± 20 vs 383 ± 21 ms, P < 0.01), and of 400 ms (390 ± 21 vs 362 ± 17 ms, P < 0.001). During sinus rhythm the mean values of QT_C were similar in both groups (408 ± 25 vs 413 ± 20 ms, NSJ. During ventricular stimulation the percentage of patients with values of QT-V exceeding 380 ms was 35% in non-VT group and 95% in VT group (P <0.01) at cycle length of 500 ms and 5% versus 60%, respectively, (P < 0.01), at cycle length of 400 ms. Thus, a trend toward longer QT values of ventricular paced rhythm exists in patients with inducible VT.     

Ibutilide for treatment of atrial fibrillation in the emergency department

The purpose of this study was to assess the efficacy and safety of ibutilide, a class III antiarrhythmic drug, for acute treatment of atrial fibrillation (AF) in the emergency department (ED) setting. A retrospective analysis was done reviewing all patients with AF who received ibutilide in the ED in a university hospital setting. A total of 22 patients received ibutilide. Another 24 patients who received rate control drugs only served as a control group. Of the 22 patients who received ibutilide, 14 (64%) converted to sinus rhythm. The mean (SD) rate of AF was 137 (24) bpm and the mean QTc interval immediately after conversion to sinus rhythm was 420 (28) ms. There were no complications. In the rate control group 7 patients (29%) converted to sinus rhythm (p<0.05, compared with ibutilide). The mean rate of AF was 126 (26) bpm (p = ns, compared with ibutilide) and the mean QTc interval in those who converted was 377 (28) ms (p<0.05, compared with ibutilide). One patient developed severe bradycardia. Ibutilide is effective for conversion of recent onset AF in patients presenting to the ED and there is a low rate of complications from ibutilide in this setting.     

Fast Track and the Pediatric Emergency Department: Resource Utilization and Patient Outcomes

OBJECTIVE: To examine differences in the evaluation, management, and outcomes for patients seen in an on-site "fast track" (FT) vs the main ED. METHODS: Over a three-month period, patients presenting to an urban pediatric ED were prospectively assessed. Patients included were: triaged as "nonurgent"; aged 2 months to 10 years; not chronically ill; and had fever, or complaint of vomiting, diarrhea, or decreased oral intake. Evening and weekend care was provided in the FT; at all other times these low-acuity patients were seen in the ED. Seven days after the visit, families were interviewed by telephone. RESULTS: Four hundred seventy-nine and 557 patients were seen in the FT and ED, respectively. The patients in the two settings did not differ in age, clinical condition, race, or commercial insurance status. Patient mean test charges were $27 and $52 for the FT and ED, respectively (p < 0.01). Twenty-four percent of the FT patients vs 41% of the ED patients had tests performed (p < 0.01). Average length of stay was 28 minutes shorter in the FT (95% CI = 19 to 36, p < 0.01). Follow-up was completed for 480 of 755 families with telephones (64%). The FT and ED patients did not differ at follow-up: 90% vs 88% had improved conditions (p = 0.53), 18% vs 15% had received unscheduled follow-up care (p = 0.44), and 94% of the families in both groups were satisfied with the visit (p = 0.98). CONCLUSIONS: Compared with those in the main ED, the study patients seen in the FT had fewer tests ordered and had briefer lengths of stay. These findings were not explained by differences in patient ages, vital signs, or demographic characteristics. No difference in final outcomes or satisfaction was detected among the families contacted for follow-up.     

Exact Location of the Branching Bundle in the Living Heart

Aims: The His bundle electrogram is believed to reflect the exact location of the His bundle. However, the distinction between distal His bundle potential and proximal right bundle branch potential is challenging. The aim of this study was to pinpoint the location of the branching point of the His bundle, and to compare that site with the site of recording of the largest His bundle electrogram (LH) during sinus rhythm.
Methods: We hypothesized that the site of earliest His activation (EH) during retrograde conduction via the left bundle branch is the branching point. We studied 15 nonconsecutive patients (mean age = 40 ± 22 years; eight men). We performed a programmed stimulation from right ventricular apex until retrograde right bundle branch block appeared. At that point we measured (1) the distance between antegrade LH site and retrograde EH site and (2) the atrial-to-ventricular amplitude ratio (A/V ratio) at both sites.
Results: EH was recorded at the proximal electrode of the His bundle catheter in all patients. Mean distance between EH and LH was 9.8 ± 2.5 mm. The mean A/V ratios at the EH site and the LH site were 1.01 ± 0.42 and 0.08 ± 0.06, respectively.
Discussion: This study showed that the EH site is located approximately 10-mm proximal to the LH site. The mean A/V ratio at the EH site during sinus rhythm is approximately 1.0. These observations suggest that the majority of His potentials reflect proximal right bundle activation. Before delivering radiofrequency energy in the para-Hisian area, attention should be paid to the presence of a His potential and to the A/V ratio, rather to the amplitude of the His electrogram.     

Treatment of Out-of-hospital Supraventricular Tachycardia: Adenosine vs Verapamil

Objective: To compare the use of adenosine and the use of verapamil as out-of-hospital therapy for supraventricular tachycardia (SVT). Methods: A period of prospective adenosine use (March 1993 to February 1994) was compared with a historical control period of verapamil use (March 1990 to February 1991) for SVT. Data were obtained for SVT patients treated in a metropolitan, fire-department-based paramedic system serving a population of approximately 1 million persons. Standard drug protocols were used and patient outcomes (i.e., conversion rates, complications, and recurrences) were monitored. Results: During the adenosine treatment period, 105 patients had SVT; 87 (83%) received adenosine, of whom 60(69%) converted to a sinus rhythm (SR). Vagal maneuvers (VM) resulted in restoration of SR in 8 patients (7.6%). Some patients received adenosine for non-SVT rhythms: 7 sinus tachycardia, 18 atrial fibrillation, 7 wide-complex tachycardia (WCT), and 2 ventricular tachycardia; no non-SVT rhythm converted to SR and none of these patients experienced an adverse effect. Twenty-five patients were hemodynamically unstable (systolic blood pressure < 90 mm Hg), with 20 receiving drug and 13 converting to SR; 8 patients required electrical cardioversion. Four patients experienced adverse effects related to adenosine (chest pain, dyspnea, prolonged bradycardia, and ventricular tachycardia). In the verapamil period, 106 patients had SVT; 52 (49%) received verapamil (p < 0.001, compared with the adenosine period), of whom 43 (88%) converted to SR (p = 0.11). Two patients received verapamil for WCT; neither converted to SR and both experienced cardiovascular collapse. VM resulted in restoration of SR in 12 patients (11.0%) (p = 0.52). Sixteen patients were hemodynamically unstable, with 5 receiving drug (p = 0.005) and 5 converting to SR; 9 patients required electrical cardioversion (p = 0.48). Four patients experienced adverse effects related to verapamil (hypotension, ventricular tachycardia, ventricular fibrillation). Recurrence of SVT was noted in 2 adenosine patients and 2 verapamil patients in the out-of-hospital setting and in 23 adenosine patients and 15 verapamil patients after ED arrival, necessitating additional therapy (p = 0.48 and 0.88, for recurrence rates and types of additional merapies, respectively). Hospital diagnoses, outcomes, and ED dispositions were similar for the 2 groups. Conclusion: Adenosine and verapamil were equally successful in converting out-of-hospital SVT in patients with similar etiologies responsible for the SVT. Recurrence of SVT occurred at similar rates for the 2 medications. Rhythm misidentification remains a common issue in out-of-hospital cardiac care in this emergency medical services system.