Recent Caffeine Ingestion Reduces Adenosine Efficacy in the Treatment of Paroxysmal Supraventricular Tachycardia

Objectives:  Caffeine, an adenosine receptor blocker, should theoretically reduce adenosine efficacy in the treatment of paroxysmal supraventricular tachycardia (SVT). We aimed to determine the effect of recent caffeine ingestion on the likelihood of reversion of SVT with adenosine.
Methods:  This was a multicenter, case–control study of adult patients with SVT treated with adenosine between September 2007 and July 2008. The primary endpoint was reversion to sinus rhythm (SR) after a 6-mg adenosine bolus, as a function of recent (within 2, 4, 6, and 8 hours) caffeine ingestion. Caffeine ingestion data were collected using a self-administered questionnaire.
Results:  Of 68 patients enrolled, 52 (76.5%, 95% confidence interval [CI] = 64.4% to 85.6%) reverted after a 6-mg adenosine bolus. There were no significant differences in age, sex, or daily caffeine ingestion between patients who did and did not revert (p > 0.05). However, as a group, patients who did not revert had recently ingested significantly more caffeine (p < 0.05). If caffeine had been ingested less than 2 or 4 hours before the adenosine bolus, the odds of reversion to SR were significantly reduced (odds ratio [OR] = 0.18, 95% CI = 0.04 to 0.93; and OR = 0.14, 95% CI = 0.04 to 0.49, respectively). If caffeine had been ingested less than 6 or 8 hours before the adenosine, the odds of reversion were not reduced (OR = 0.31, 95% CI = 0.09 to 1.02; and OR = 0.31, 95% CI = 0.09 to 1.08, respectively).
Conclusions:  Ingestion of caffeine less than 4 hours before a 6-mg adenosine bolus significantly reduces its effectiveness in the treatment of SVT. An increased initial adenosine dose may be indicated for these patients.
ACADEMIC EMERGENCY MEDICINE 2010; 17:44–49 © 2009 by the Society for Academic Emergency Medicine     

Surgical Treatment of Supraventricular Tachycardia: A Five-Year Experience

Two hundred and eight patients underwent operative therapy of supraventricular tachycardia between June 1984 and June 1986. There were 196 patients with Wolff-Parkinson-White syndrome, one with AV nodal reentry, two with atrial flutter, one with ectopic atrial tachycardia, three with paroxysmal sinus tachycardia, and five with atrial fibrillation. Map guided or direct surgery was performed in all patients except the three with atrial fibrillation. Direct surgery was generally successful with failures including one patient with Wolff-Parkinson-White syndrome, one with atrial flutter, and the three patients with paroxysmal sinus tachycardia. There was no mortality. Major complications were uncommon and included three resternotomies for bleeding, one chylopericardium. Six patients required reoperation.     

Provocation of Atrioventricular Reentry Tachycardia: A Paradoxical Effect of Adenosine

Adenosine has been used to diagnose latent preexcitation in patients with the Wolff-Parkinson-White syndrome. A case is reported in which intermittent preexcitation had been previously observed, however only retrograde accessory pathway conduction was documented at the time of invasive eiectrophysiological study, Administration of intravenous adenosine during sinus rhythm resulted in provocation of orthodromic atrioventricular reentry tachycardia.     

Intravenous vs Subcutaneous Naloxone for Out-of-hospital Management of Presumed Opioid Overdose

Objective : To determine whether naloxone administered IV to out-of-hospital patients with suspected opioid overdose would have a more rapid therapeutic onset than naloxone given subcutaneously (SQ).
Methods : A prospective, sequential, observational cohort study of 196 consecutive patients with suspected opioid overdose was conducted in an urban out-of-hospital setting, comparing time intervals from arrival at the patient's side to development of a respiratory rate ≥10 breaths/min, and durations of bag-valve-mask ventilation. Subjects received either naloxone 0.4 mg IV ( n = 74) or naloxone 0.8 mg SQ ( n = 122), for respiratory depression of <10 breaths/min.
Results : Mean interval from crew arrival to respiratory rate ≥ 10 breaths/min was 9.3 ± 4.2 min for the IV group vs 9.6 ± 4.58 min for the SQ group (95% CI of the difference -1.55, 1.00). Mean duration of bag-valve-mask ventilation was 8.1 ± 6.0 min for the IV group vs 9.1 ± 4.8 min for the SQ group. Cost of materials for administering naloxone 0.4 mg IV was $12.30/patient, compared with $10.70/patient for naloxone 0.8 mg SQ.
Conclusion : There was no clinical difference in the time interval to respiratory rate ≥10 breaths/min between naloxone 0.8 mg SQ and naloxone 0.4 mg IV for the out-of-hospital management of patients with suspected opioid overdose. The slower rate of absorption via the SQ route was offset by the delay in establishing an IV.     

Patient Refusal of Care in the Out-of-hospital Setting

A case vignette of out-of-hospital refusal of emergency care is reported with accompanying discussion. This case illustrates the challenges faced by out-of-hospital emergency care personnel in these scenarios and provides guidance to the emergency physician and emergency medical technician. Recommendations are provided for preparing the emergency medical services system to handle these cases.     

Oral Flecainide, Sotalol, and Verapamil for the Termination of Paroxysmal Supraventricular Tachycardia

The ability to terminate supraventricular tachycardia (SVT) acutely with an oral dose of flecainide (2.5–3.3 mg/kg). sotalol (2.0–2.9 mg/kg), and verapamil (3.3–3.7 mg/kg) was investigated in an observational study of six patients u'ith SVT normally controlled by an antitachycardia pacemaker. The pacemaker was programmed to induce SVT and the stahility of SVT was observed for 90 minutes as a baseline. Subsequent studies involved testing of the three antiarrhythmic drugs on separate occasions, given in random order as crushed tablets in orange juice during pacemaker induced SVT, with plasma drug levels collected every 15 minutes for 90 minutes post drug ingestion. Sotalol produced drug induced slowing of SVT in all six patients, with termination of SVT in three patients by 60–65 minutes, with maximum plasma levels of 0.76–2.09 μg/mL achieved by 90 minutes. Flecainide produced maximum plasma levels of 83–745 ng/mL, 60–90 minutes post ingestion, and slowed SVT in three patients, SVT was terminated in three patients after 45–85 minutes, but no effect on SVT was seen in two patients who had inodequate plasma levels (≤ 166 ng/mL) from doses < 3 mg/kg. Verapamil produced maximum plasma levels of 0 (undetectable) to 388 ng/mL, 45–90 minutes post ingestion, and slowed SVT in three patients, but only one of these patients reverted to sinus rhythm (at 40 min). No effect on SVT was seen in three patients due to undetecfable plasma levels. We concluded that sotalol (≤ 2 mg/kg) and flecainide (≤ 3 mg/kg) appeared to be suitable oral drugs for termination of SVT. Verapamil appeared unsuitable due to its unpredictable bioavailability, despite the use of high doses (> 3 mg/kg).     

Adenosine and Verapamil-Sensitive Ventricular Tachycardia Originating From the Left Ventricle: Radiofrequency Catheter Ablation

A ventricular tachycardia (VT) with right bundle branch block (RBBB) QRS morphology and left axis originating from the inferoapical segment of the left ventricle is described in a 49-year-old man without structural heart disease. This VT could be initiated during isoproterenol infusion and was terminated with intravenous administration of adenosine and verapamil. Radiofrequency ablation eliminated the tachycardia. Previous reports have suggested reentry as the mechanism for a verapamil-sensitive VT with this ECG morphology, while cAMP-mediated triggered activity has been proposed as a mechanism for VTs sensitive to adenosine. The latter more typically arise in the right ventricular outflow tract. The electrophysiological and electropharmacological characteristics of the tachycardia in this patient suggest that this VT morphology is not specific for a mechanism but rather for the location of the site of origin.     

U22, a Protocol to Quantify Symptoms Associated with Supraventricular Tachycardia

Background: The main indication for ablation of supraventricular tachyarrhythmias (SVTA) is symptomatic relief. Specific paroxysmal symptoms cannot be quantified with general measures of quality of life, such as with the SF-36 questionnaire. U22 is a new protocol which measures the effects of arrhythmia on well-being, the intensity of discomfort during an episode, the type and temporal characteristics of dominant symptoms, and the duration and frequency of episodes. Discrete 0–10 scales are used. Unlike SF-36, U22 can be used in individual patients.
Methods: U22 and SF-36 protocols were used in the symptomatic evaluation of 88 patients (mean age = 49.6 ± 16.4 years; 43 men), who underwent catheter ablation of SVTA.
Results: The U22 scores (SD) for (a) well-being (10 being best), (b) effects of arrhythmia on well-being (10 being worst), and (c) discomfort during arrhythmia (10 being worst) were 5.6 (2.7), 7.5 (2.8), and 8.0 (2.4), respectively. For comparison, the physical and mental component summaries of SF-36 were 45.3 (11.0) and 45.2 (12.1), respectively, slightly lower than the expected normal of 50. The intensity of dominant symptom scored by U22 was 9.7 (1.2), 10 being worst. In 29% of patients ≥4 symptoms were equally dominant. Multiple dominant symptoms in U22 were associated with a low general well-being in SF-36.
Conclusion: We found U22 useful to quantify symptoms associated with SVTA.     

Out-of-hospital Treatment of Opioid Overdoses in an Urban Setting

Objectives : To investigate clinical outcomes in a cohort of opioid overdose patients treated in an out-of-hospital urban setting noted for a high prevalence of IV opioid use. Methods : A retrospective review was performed of presumed opioid overdoses that were managed in 1993 by the emergency medical services (EMS) system in a single-tiered, urban advanced life support (ALS) EMS system. Specifically. all patients administered naloxone by the county paramedics were reviewed. Those patients with at least 3 of 5 objective criteria of an opioid overdose [respiratory rate <6/min, pinpoint pupils, evidence of IV drug use, Glasgow Coma Scale (GCS) score <12, or cyanosis] were included. A response to naloxone was defined as improvement to a GCS 14 and a respiratory rate 10/min within 5 minutes of naloxone administration. ED dispositions of opioid-overdose patients brought to the county hospital were reviewed. All medical examiner's cases deemed to be opioid-overdose-related deaths by postmortem toxicologic levels also were reviewed. Results : There were 726 patients identified with presumed opioid overdoses. Most patients (609/726, 85.4%) had an initial pulse and blood pressure (BP). Most (94%) of this group responded to naloxone and all were transported. Of the remainder, 101 (14%) had obvious signs of death and 16 (2.2%) were in cardiopulmonary arrest without obvious signs of death. Of the patients in full arrest, 2 had return of spontaneous circulation but neither survived. Of the 609 patients who had initial BPs, 487 (80%) received naloxone IM (plus bag-valve-mask ventilation) and 122 (20%) received the drug IV. Responses to naloxone were similar; 94% IM vs 90% IV. Of 443 patients transported to the county hospital, 12 (2.7%) were admitted. The admitted patients had noncardiogenic pulmonary edema (n = 4). pneumonia (n = 2), other infections (n = 2), persistent respiratory depression (n = 2). and persistent alteration in mental status (n = 2). The patients with pulmonary edema were clinically obvious upon ED arrival. Hypotension was never noted and bradycardia was seen in only 2% of our presumed-opioid:overdose population. Conclusions : The majority of the opioid-overdose patients who had initial BPs responded readily to naloxone, with few patients requiring admission. Noncardiogenic pulmonary edema was uncommon and when present, hypoxia was evident upon arrival to the ED. Naloxone administered IM in conjunction with bag-valve-mask ventilation was effective in this patient population. The opioid-overdose patients in cardiopulmonary arrest did not survive.     

Supraventricular Tachycardia Cardioverted by an Automated External Debrillator in a 9-year-old Male with a History of Wolff-Parkinson-White Syndrome

Abstract

Early defibrillation for cardiac arrest patients is a formidable link in the chain of survival promulgated by the American Heart Association. Automated external defibrillators (AEDs) provide public access defibrillation for out-of-hospital cardiac arrests and improve survivability. AEDs are only approved for use in patients in cardiac arrest; defibrillation may be inadvertently advised if utilized on a patient not experiencing cardiac arrest. We describe a case report of an AED cardioversion of a stable, pediatric patient with acute supraventricular tachycardia secondary to underlying Wolff-Parkinson-White syndrome. We discuss general AED principles, the cardioversion function on the particular AED used in this encounter, and the importance of community and organizational policies to encourage the correct application of AEDs.     

Early Stroke Recognition: Developing an Out-of-hospital NIH Stroke Scale

Objective : To develop an abbreviated and practical neurologic scale that could assist emergency medical services or triage personnel in identifying patients with stroke.
Methods : A prospective, observational, cohort study was performed at university-based EDs. Participants were 74 patients treated in a thrombolytic stroke trial and 225 consecutive non-stroke patients evaluated during 4 random 12-hour shifts in the ED. Scores on the NIH Stroke Scale were obtained for all patients by physicians. Items of this scale were modified and recoded to a binomial (normal or abnormal) scale. Serial univariate analyses using χ² were performed to rank items. Recursive partitioning was then performed to develop the decision rule for predicting the presence of stroke.
Results : Three items identified 100% of patients with stroke: facial palsy, motor arm, and dysarthria. An Abbreviated NIH Stroke Scale based on these items had a sensitivity of 100% and a specificity of 92%. A proposed Out-of-hospital NIH Stroke Scale consisting of facial palsy, motor arm, and a combination of dysarthria and best language items (abnormal speech) had a sensitivity of 100% and a specificity of 88%.
Conclusion : Using the derivation data set, a proposed Out-of-hospital NIH Stroke Scale had a high sensitivity and specificity for identifying patients with stroke when performed by physicians in this group of 299 ED patients. Prospective studies of other health care professionals using the scale in the out-of-hospital arena are needed.     

国产艾司洛尔治疗阵发性室上性心动过速的临床观察

目的:评价国产艾司洛尔治疗阵发性室上性心动过速的疗效和安全性。方法:用国产艾司洛尔治疗阵发性室上性心动过速42例,观察其转复窦性心律和控制心室率的情况,并记录用药前后的血压变化。结果:静脉注射国产艾司洛尔起效时间为4.2±1.5分钟,治疗有效率为78.6％;副作用较少,静脉注射后仅轻度影响收缩压,共有4例出现低血压,给予快速补液后好转。结论:国产艾司洛尔不仅能有效地转复阵发性室上性心动过速,而且使用安全。     

Verapamil or Adenosine for the Immediate Treatment of Supraventricular Tachycardia

A comparison of verapamil with adenosine for the immediate treatmentof supraventricular tachycardia was made from a retrospectivereview of 164 spontaneous episodes of paroxysmal tachycardiain 43 patients. Verapamil administered to 33 patients restoredsinus rhythm in 91 of 112 episodes (81 per cent). Hypotensionoccurred in 9 per cent of episodes. Adenosine terminated 94per cent of episodes of supraventricular tachycardia in 25 patients.The arrhythmia recurred shortly after adenosine restored sinusrhythm in 20 episodes. Transient side effects were common. Fifteenpatients were treated with both agents. Adenosine was successfulin all, but verapamil failed to restore sinus rhythm at leastonce in seven of the 15 patients. Early recurrence of tachycardiaoccurred in five of these after adenosine, but in only one afterverapamil. Verapamil and adenosine are both effective in the treatmentof supraventricular tachycardia; adenosine has the higher successrate and is safer, but transient symptoms are common and arrhythmiasmay recur.     

Review article: Adenosine use in the emergency department

Objective: To perform a review of the efficacy of adenosine, including its potential role as first‐line treatment in unstable supraventricular tachycardia (SVT) and its use in wide complex tachycardias and diagnosing difficult arrhythmias. The dose and administration, nature and frequency of side‐effects and relevant interactions and dosage adjustments are also discussed. Methods: A search of the Medline database from 1950 to 2007 and the Embase Database from 1974 to 2007 was carried out. A manual search was performed of references of each article. Results: Adenosine is efficacious at treating stable SVT, but it is no more effective than cheaper alternatives. It has a possible role in the first‐line treatment of unstable SVT and is generally safe and effective when used to treat and/or diagnose wide complex tachycardias. There is a small risk of inducing serious arrhythmias, such as prolonged atrioventricular blockade and ventricular fibrillation. There is evidence that recommended initial doses for infants might be too low, but initial doses for children and adults are adequate. There is evidence that central venous administration requires lower doses, but there are no studies addressing peripheral sites of administration and size of flush. Minor and self‐limiting side‐effects are common. The need for dosage adjustments in the presence of interacting medications is well documented, but no studies have addressed how to rationally effect these adjustments. Conclusion: There is extensive evidence showing adenosine to be efficacious at treating SVT, but no more efficacious than cheaper alternatives. More studies are required to investigate other areas of adenosine use.