Acute conversion of paroxysmal supraventricular tachycardia with intravenous diltiazem. IV Diltiazem Study Group

Keeping It "Current": A Review of Treatment Options for the Management of Supraventricular Tachycardia

OBJECTIVE

To review treatment options and updates that exist for the management of paroxysmal supraventricular tachycardia (PSVT).

DATA SOURCES

A literature search of PubMed was performed including articles from 1974 to June 2023 using the terms: arrhythmias, adenosine, verapamil, diltiazem, esmolol, propranolol, metoprolol, beta-blockers, amiodarone, PSVT, synchronized cardioversion, methylxanthines, dipyridamole, pediatrics, heart transplant, and pregnancy. Primary literature and guidelines were reviewed.

STUDY SELECTION AND DATA EXTRACTION

Studies were considered if they were available in English and conducted in humans.

DATA SYNTHESIS

PSVT is a subset of supraventricular tachycardia (SVT) that presents as a rapid, regular tachycardia with an abrupt onset and termination. Due to frequent emergency department (ED) visits annually with symptoms of PSVT, appropriate and efficient management of these patients is vital. This review provides an overview of the pathophysiology of PSVT, while also describing the literature behind nonpharmacologic and pharmacologic management of PSVT.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

This review describes new literature regarding the improved success of the modified Valsalva maneuver as a nonpharmacologic therapy in PSVT. In addition, it describes a new technique in administration of adenosine that has improved outcomes, defines dose adjustments needed for drug interactions with adenosine, compares the utilization of nondihydropyridine calcium channel blockers with adenosine, and provides management recommendations for patients in special populations.

CONCLUSIONS

With high annual rates of ED visits for SVT, providers should be aware of the data behind management and modifications of therapy based on patient-specific factors (ie, patient preference, pharmacokinetics/pharmacodynamics, drug interactions, and special populations).

Diltiazem Dosing Strategies in the Management of Atrial Fibrillation With Rapid Ventricular Rate

Introduction

Diltiazem is commonly used for the management of atrial fibrillation (AFIB) with rapid ventricular rate (RVR) in the emergency department (ED). Conflicting studies comparing the efficacy of diltiazem have led to various dosing strategies. The objective of this study was to investigate diltiazem administration in a community ED and determine the effect of varying doses on heart rate (HR) control, systolic blood pressure (SBP) and diastolic blood pressure (DBP).

Methods

This is a retrospective, single-center study of adult patients treated with diltiazem for AFIB-RVR in the ED between January 1 and December 31, 2019. Inclusion criteria included pretreatment HR > 120 beats per minute (bpm). Patients were administered diltiazem at the discretion of the ED physician. Primary endpoint was time to achieve HR < 100 bpm after diltiazem. Secondary endpoints included mean weight-based dose of diltiazem, percentage of patients achieving HR < 100 bpm within 240 minutes of diltiazem, nadir SBP and nadir DBP.

Results

Ninety-nine patients were included in the study. Seventy-two percent of patients received ≤ 10 mg diltiazem bolus. Mean weight-based dose of diltiazem bolus was 0.13 mg/kg. Mean time to achieve HR < 100 bpm was 270 minutes for the entire cohort. Patients treated with ≥ 0.13 mg/kg diltiazem achieved an HR < 100 bpm at a mean time of 169 minutes compared to 318 minutes for < 0.13 mg/kg (p = 0.0107). HR control was achieved in 61% of patients who received ≥ 0.13 mg/kg compared to 36% of patients who received < 0.13 mg/kg diltiazem (p = 0.0213). No patients discontinued diltiazem for hypotension or bradycardia. The lowest recorded SBP and DBP within 240 minutes of diltiazem were 90 mmHg and 47 mmHg, respectively. There was no significant difference in the lowest SBP and DBP for patients who received < 0.13 mg/kg compared to ≥ 0.13 mg/mg diltiazem.

Conclusion

The majority of patients with AFIB RVR received a 10 mg non-weight-based diltiazem bolus dose in the ED. Diltiazem bolus dosing ≥ 0.13 mg/kg was associated with significantly improved times to achieve HR control compared to < 0.13 mg/kg and was not associated with hypotension or bradycardia.

Overview of drug treatment for paroxysmal supraventricular tachycardia in Taiwan emergency departments: Adenosine using trend from 2000 to 2012

BACKGROUND

Before 2010, guidelines recommended adenosine 6, 12, and a repeat dose of 12 mg for paroxysmal supraventricular tachycardia (PSVT). After 2010, these doses were reduced to two. This study aims to outline adenosine using trend from 2000 to 2012 in Taiwan emergency departments (EDs).

METHODS

This was an ecological study. PSVT were drawn from one million individuals of the National Health Insurance Database. The χ² test was used to determine an association between different adenosine doses and other antiarrhythmic drugs (OADs), including verapamil, diltiazem, amiodarone, digoxin, and labetalol.

RESULTS

There were 3361 PSVT visits from 2000 to 2012; 834 (24.8%) did not receive an antiarrhythmic drug, and 2527 (75.2%) did, either adenosine with/without OADs or OADs alone. The use of an OAD was significantly different between the adenosine 6-18 mg and 19 + mg groups.

CONCLUSIONS

Most PSVT episodes converted with adenosine within 18 mg, and the success conversion rate was 62.2%. It could be up to 65.2% if they received more. Of the patients who did not have their PSVT reverted with< 18 mg, 37.8% could have been successfully treated with more doses. The necessity of using the 3rd dose of adenosine is needed to be further explored.

[Adult advanced life support]

These European Resuscitation Council Advanced Life Support guidelines are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

In The Line of Treatment: A Systematic Review of Paroxysmal Supraventricular Tachycardia

Paroxysmal supraventricular tachycardia (PSVT) is a common tachyarrhythmia, and an electrocardiogram is the best tool for making a diagnosis. If Valsalva maneuvers and carotid sinus massage do not give positive results, then the next choice is either adenosine or calcium channel blockers. At this time, adenosine is the drug of choice of treatment. Verapamil and diltiazem are the most commonly used calcium channel blockers (CCBs). This review aimed to compare the efficacy of both drugs in the treatment of PSVT.

We utilized the databases PubMed Central and Medline by using keywords: "calcium channel blockers OR adenosine AND supraventricular tachycardia." In the end, we finalized 32 studies, including observational studies, literature reviews, systematic reviews/metanalysis, and randomized control trials. We included articles only in the English language and related to humans. Two authors completed the quality assessment and evaluation of bias according to specific guidelines. Only high-quality studies were included in this systematic review based on the cut-off score of seven or above. Calcium channel blockers have a longer half-life than adenosine and were previously used as the drug of choice in the treatment of PSVT. Calcium channel blockers are safe if given slowly; however, adenosine is safer and useful when an electrocardiogram is uncertain. We compared both drugs in certain aspects and found equal efficacy. Though safer, adenosine was found to have a higher cost and a higher probability of re-initiation arrhythmia compared to calcium channel blockers. 

European Resuscitation Council Guidelines 2021: Adult advanced life support

These European Resuscitation Council Advanced Life Support guidelines, are based on the 2020 International Consensus on Cardiopulmonary Resuscitation Science with Treatment Recommendations. This section provides guidelines on the prevention of and ALS treatments for both in-hospital cardiac arrest and out-of-hospital cardiac arrest.

In vitro and in vivo investigation for optimization of niosomal ability for sustainment and bioavailability enhancement of diltiazem after nasal administration

Diltiazem hydrochloride (DTZ) is a calcium channel antagonist depicted by extensive first pass metabolism and low oral bioavailability. The aim of this work was to develop niosomes for potential nasal delivery of DTZ. Niosomes protect hydrophilic drugs inside their core while nasal route offers both rapid onset and evasion of first-pass metabolism. Niosomes were prepared using a combination of Span 60 or Brij-52 with cholesterol (CHOL) in different molar ratios followed by determination of entrapment efficiency, particle size and in vitro drug release. A parallel design was adopted to evaluate the pharmacokinetic performance of DTZ-loaded niosomes in male Wistar rats. Non-compartmental analysis was performed where Cmax, Tmax, t1/2, MRT, area under the release curve (AUC) and Ke were assessed. The prepared niosomes were spherical with mean particle size 0.82-1.59 μm. Span 60-cholesterol niosomes (1:1 molar ratio) showed the highest entrapment and release efficiencies. In vivo study revealed an increase in MRT, t1/2 and AUC with a decrease in Ke. In conclusion, nasal niosomal formulation of DTZ expressed suitable pharmacokinetic parameters and bioavailability through prolonged duration of action inside the body as well as low rate of elimination depicting a promising alternate to the conventional oral route.

Adenosine versus intravenous calcium channel antagonists for supraventricular tachycardia

BACKGROUND

People with supraventricular tachycardia (SVT) frequently are symptomatic and present to the emergency department for treatment. Although vagal manoeuvres may terminate SVT, they often fail, and subsequently adenosine or calcium channel antagonists (CCAs) are administered. Both are known to be effective, but both have a significant side effect profile. This is an update of a Cochrane review previously published in 2006.

OBJECTIVES

To review all randomised controlled trials (RCTs) that compare effects of adenosine versus CCAs in terminating SVT.

SEARCH METHODS

We identified studies by searching CENTRAL, MEDLINE, Embase, and two trial registers in July 2017. We checked bibliographies of identified studies and applied no language restrictions.

SELECTION CRITERIA

We planned to include all RCTs that compare adenosine versus a CCA for patients of any age presenting with SVT.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by Cochrane. Two review authors independently checked results of searches to identify relevant studies and resolved differences by discussion with a third review author. At least two review authors independently assessed each included study and extracted study data. We entered extracted data into Review Manager 5. Primary outcomes were rate of reversion to sinus rhythm and major adverse effects of adenosine and CCAs. Secondary outcomes were rate of recurrence, time to reversion, and minor adverse outcomes. We measured outcomes by calculating odds ratios (ORs) and assessed the quality of primary outcomes using the GRADE approach through the GRADEproGDT website.

MAIN RESULTS

We identified two new studies for inclusion in the review update; the review now includes seven trials with 622 participants who presented to an emergency department with SVT. All included studies were RCTs, but only three described the randomisation process, and none had blinded participants, personnel, or outcome assessors to the intervention given. Moderate-quality evidence shows no differences in the number of people reverting to sinus rhythm who were treated with adenosine or CCA (89.7% vs 92.9%; OR 1.51, 95% confidence interval (CI) 0.85 to 2.68; participants = 622; studies = 7; I² = 36%). Low-quality evidence suggests no appreciable differences in major adverse event rates between CCAs and adenosine. Researchers reported only one case of hypotension in the CCA group and none in the adenosine group (0.66% vs 0%; OR 3.09, 95% CI 0.12 to 76.71; participants = 306; studies = 3; I² = 0%). Included trials did not report length of stay in hospital nor patient satisfaction.

AUTHORS' CONCLUSIONS

Moderate-quality evidence shows no differences in effects of adenosine and calcium channel antagonists for treatment of SVT on reverting to sinus rhythm, and low-quality evidence suggests no appreciable differences in the incidence of hypotension. A study comparing patient experiences and prospectively studied adverse events would provide evidence on which treatment is preferable for management of SVT.

Computational approaches to understand the adverse drug effect on potassium, sodium and calcium channels for predicting TdP cardiac arrhythmias

Ion channels play a crucial role in the cardiovascular system. Our understanding of cardiac ion channel function has improved since their first discoveries. The flow of potassium, sodium and calcium ions across cardiomyocytes is vital for regular cardiac rhythm. Blockage of these channels, delays cardiac repolarization or tend to shorten repolarization and may induce arrhythmia. Detection of drug risk by channel blockade is considered essential for drug regulators. Advanced computational models can be used as an early screen for torsadogenic potential in drug candidates. New drug candidates that are determined to not cause blockage are more likely to pass successfully through preclinical trials and not be withdrawn later from the marketplace by manufacturer. Several different approved drugs, however, can cause a distinctive polymorphic ventricular arrhythmia known as torsade de pointes (TdP), which may lead to sudden death. The objective of the present study is to review the mechanisms and computational models used to assess the risk that a drug may TdP.

KEY POINTS

There is strong evidence from multiple studies that blockage of the L-type calcium current reduces risk of TdP. Blockage of sodium channels slows cardiac action potential conduction, however, not all sodium channel blocking antiarrhythmic drugs produce a significant effect, while late sodium channel block reduces TdP. Interestingly, there are some drugs that block the hERG potassium channel and therefore cause QT prolongation, but they are not associated with TdP. Recent studies confirmed the necessity of studying multiple distinctionic ion channels which are responsible for cardiac related diseases or TdP, to obtain an improved clinical TdP risk prediction of compound interactions and also for designing drugs.

Executive Summary: European Heart Rhythm Association Consensus Document on the Management of Supraventricular Arrhythmias: Endorsed by Heart Rhythm Society (HRS), Asia-Pacific Heart Rhythm Society (APHRS), and Sociedad Latinoamericana de Estimulación Cardiaca y Electrofisiologia (SOLAECE)

This paper is an executive summary of the full European Heart Rhythm Association (EHRA) consensus document on the management of supraventricular arrhythmias, published in Europace. It summarises developments in the field and provides recommendations for patient management, with particular emphasis on new advances since the previous European Society of Cardiology guidelines. The EHRA consensus document is available to read in full at http://europace.oxfordjournals.org.

Effects of prototypic calcium channel blockers in methadone-maintained humans responding under a naloxone discrimination procedure

Accumulating evidence suggests that L-type calcium channel blockers (CCBs) attenuate the expression of opioid withdrawal and the dihydropyridine L-type CCB isradipine has been shown to block the behavioral effects of naloxone in opioid-maintained humans. This study determined whether two prototypic L-type CCBs with differing chemical structures, the benzothiazepine diltiazem and the phenylalkamine verapamil, attenuate the behavioral effects of naloxone in methadone-maintained humans trained to distinguish between low-dose naloxone (0.15 mg/70 kg, i.m.) and placebo under an instructed novel-response drug discrimination procedure. Once discrimination was acquired, diltiazem (0, 30, 60, 120 mg) and verapamil (0, 30, 60, 120 mg), alone and combined with the training dose of naloxone, were tested. Diltiazem alone produced 33-50% naloxone- and novel-appropriate responding at 30 and 60 mg and essentially placebo-appropriate responding at 120 mg. Verapamil alone produced 20-40% naloxone- and 0% novel-appropriate responding. Diltiazem at 60 mg decreased several ratings associated with positive mood and increased VAS ratings of "Bad Drug Effects" relative to placebo, whereas verapamil increased ratings associated with euphoria. When administered with naloxone, diltiazem produced 94-100% naloxone-appropriate-responding with 6% novel-appropriate responding at 60 mg (n=3). When administered with naloxone, verapamil produced 60-80% naloxone- and 0% novel-appropriate responding (n=5). Diltiazem decreased diastolic blood pressure and heart rate whereas verapamil decreased ratings of arousal relative to placebo. These results suggest that CCBs with different chemical structures can be differentiated behaviorally, and that diltiazem and verapamil do not attenuate the discriminative stimulus effects of naloxone in humans at the doses tested.

WITHDRAWN: Adenosine versus intravenous calcium channel antagonists for the treatment of supraventricular tachycardia in adults

BACKGROUND

Patients with paroxysmal supraventricular tachycardia frequently present to the Emergency Department. Where vagal manoeuvres fail, the two most commonly used drugs are adenosine and calcium channel antagonists. Both are known to be effective but both have a significant side-effect profile.

OBJECTIVES

To examine the relative effects of adenosine and calcium channel antagonists and, if possible, to determine which is most appropriate for the management of supraventricular tachycardia.

SEARCH METHODS

Studies were identified from The Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library, Issue 2, 2010, MEDLINE (1966 to May Week 1 2010) and EMBASE (1980 to 2010 week 19). The searches were originally run in June 2006 and updated and re-run in May 2010. Bibliographies of identified studies were also examined. No language restrictions were applied.

SELECTION CRITERIA

Randomised trials comparing adenosine and a calcium channel antagonist in patients of any age with supraventricular tachycardia, where one of the defined outcomes was reported. Outcomes of interest were: reversion rate, mortality, time to reversion, rate of relapse, major and minor adverse events, length of hospital stay and patient satisfaction.

DATA COLLECTION AND ANALYSIS

Two authors independently checked the results of searches to identify relevant studies. Dichotomous outcomes were reported as Peto Odds ratios and continuous outcomes as weighted mean differences.

MAIN RESULTS

A total of ten trials were identified (two new trials were identified through the updated search in May 2010), all of which used verapamil as the calcium antagonist. In the pooled analysis there was no significant difference in reversion rate between the two drugs. Time to reversion was slower for verapamil than adenosine in all studies that reported this outcome, but the data were not suitable for combining. Relapse rates were higher for adenosine compared with verapamil (OR 0.25, 95% CI 0.07 to 0.99. P=0.05). Minor adverse events such as nausea, chest tightness, shortness of breath and headache were reported much more frequently in patients treated with adenosine with 10.8 % of patients reporting at least one of these events, compared with 0.6% of those treated with verapamil (OR 0.15, 95% CI 0.09 to 0.26, P<0.001). Hypotension was reported exclusively in the verapamil treatment group (4/214), and occurred in none of the patients treated with adenosine (OR 10.8, 95% CI 1.46 to 80.22, P=0.02).

AUTHORS' CONCLUSIONS

Adenosine and verapamil are both effective treatments for supraventricular tachycardia in the majority of patients. There is a high incidence of minor but unpleasant side effects and a greater risk of relapse in patients treated with adenosine while some patients treated with verapamil may develop significant hypotension. Patients should be fully informed of these risks prior to treatment.

Antiarrhythmic Drug Therapy of Supraventricular Tachycardia

Pharmacologic therapy is commonly used for the acute treatment and termination of paroxysmal supraventricular tachycardia (SVT) and continues to be an important long-term option for some patients. Drug choice depends on the correct diagnosis of the arrhythmia and an understanding of its mechanism. Pharmacologic agents commonly used in the acute and chronic treatment of SVT are reviewed along with their effect on the various types of SVT. Drugs that are well tolerated with minimal side effects are preferred over agents with perhaps more efficacy but higher risk of toxicity.

Adenosine versus intravenous calcium channel antagonists for the treatment of supraventricular tachycardia in adults

BACKGROUND

Patients with paroxysmal supraventricular tachycardia frequently present to the Emergency Department. Where vagal manoeuvres fail, the two most commonly used drugs are adenosine and calcium channel antagonists. Both are known to be effective but both have a significant side-effect profile.

OBJECTIVES

To examine the relative effects of adenosine and calcium channel antagonists and, if possible, to determine which is most appropriate for the management of supraventricular tachycardia.

SEARCH STRATEGY

Studies were identified from The Cochrane Central Register of Controlled Trials (CENTRAL), Issue 3 2006, MEDLINE (1966 to June 2006), Pre-MEDLINE and EMBASE (1980 to June 2006). Bibliographies of identified studies were also examined. No language restrictions were applied.

INCLUSION CRITERIA

randomised trials comparing adenosine and a calcium channel antagonist in patients of any age with supraventricular tachycardia, where one of the defined outcomes was reported. Outcomes of interest were: reversion rate, mortality, time to reversion, rate of relapse, minor adverse events, major adverse events, length of hospital stay and patient satisfaction. Major adverse events were defined as cardiac arrest, prolonged hypotension, symptomatic bradycardia requiring treatment and acute cardiac failure. Minor adverse events were any other reported event.

DATA COLLECTION AND ANALYSIS

Two reviewers independently checked the results of searches to identify relevant studies. Dichotomous outcomes were reported as Peto Odds ratios and continuous outcomes as weighted mean differences.

MAIN RESULTS

Eight trials were identified. In the pooled analysis there was no significant difference in reversion rate or relapse rate between the two drugs. Time to reversion was slower for verapamil than adenosine in all studies that reported this outcome, but the data were not suitable for combining. Minor adverse events such as nausea, chest tightness, shortness of breath and headache were reported much more frequently in patients treated with adenosine with 10.8 % of patients reporting at least one of these events, compared with 0.6% of those treated with verapamil (OR 0.15, 95% CI 0.09 to 0.26, P<0.001). There was no significant difference in the rate of major adverse events between the two groups, although hypotension was reported exclusively in the verapamil treatment group (3/166 patients treated with verapamil, 0/171 treated with adenosine).

AUTHORS' CONCLUSIONS

Adenosine and verapamil are both effective treatments for supraventricular tachycardia in the majority of patients. However, given the high incidence of minor but unpleasant side effects in patients treated with adenosine and the potential for hypotension with verapamil, patients should be fully informed of these risks prior to treatment.

Clinical significance of wide QRS complexes at the termination of paroxysmal supraventricular tachycardias

BACKGROUND

A wide QRS complex is not a rare electrocardiographic phenomenon at the termination of paroxysmal supraventricular tachycardia (PSVT), but no plausible underlying mechanism has yet been proposed. The purpose of the present study was to elucidate the frequency and the underlying mechanism of the wide QRS complexes at the termination of PSVT.

METHODS

We retrospectively reviewed 305 electrocardiograms (ECGs) from 100 patients, on which PSVT termination was recorded. The frequency of the wide QRS complexes was analyzed in 181 ECGs to avoid duplication, because there were 124 ECGs obtained from the same patients with same methods. The 181 ECGs were divided by morphology into three groups: Type A, termination with wide QRS complex without pause; Type B, wide QRS complex following initial pause after termination; Type C, wide QRS complex following the first narrow QRS after termination.

RESULTS

The wide QRS complex was recorded in 81/181 (44.8%) ECGs (Type A; 3/81 (3.7%), Type B; 44/81 (54.3%), Type C; 62/81 (55.6%) ) and its frequency was not dependent on the mechanism of PSVT. It was more frequently observed after a long pause, and was frequently induced by procedures that increase vagal tone, such as intravenous adenosine 5'-triphosphate administration (16/22: 72.7%) and vagal stimulation maneuvers (16/32: 50%). There were a total of 41 wide QRS complexes (44.6%) which had a preceding sinus P wave, out of a total of 92 wide QRS complexes in all three types. These 41 wide QRS complexes included 30/44 (68.2%) Type B wide QRS, and 11 (24.4%) Type C wide QRS complexes.

CONCLUSION

The aberrant conduction or escaped ventricular contraction was suggested to be the underlying mechanism of the majority of wide QRS complexes and ventricular premature contraction is less frequent.

Supraventricular tachycardia

Supraventricular tachycardias (SVT) comprise those tachycardias that originate above the bifurcation of the bundle of His. They can be classified broadly as AV node dependent and AV node independent. The mechanism and clinical manifestation of SVTs, which is essential to their correct diagnosis, is reviewed. The therapeutic management of SVTs, including acute and chronic drug therapy and catheter ablation, is discussed also.

Rapid reversal of life-threatening diltiazem-induced tetany with calcium chloride

We describe a patient who developed tetany with sudden respiratory arrest after the infusion of intravenous diltiazem. The administration of calcium chloride rapidly resolved the patient's tetany with prompt recovery of respiratory function, averting the need for more aggressive airway management and ventilatory support. The emergency physician should be aware that life-threatening tetany may accompany the administration of intravenous diltiazem and that calcium chloride may be a rapid and effective remedy.

Intravenous Diltiazem for Treatment of Supraventricular Tachycardia after Coronary Artery Bypass Surgery

Between 1995 and 1997, 180 patients who had undergone coronary artery bypass grafting were given intravenous diltiazem for conversion of supraventricular tachycardia to sinus rhythm or control of ventricular rhythm in atrial fibrillation. The patients were divided into three groups of 60 each: group 1 required no inotropic support; group 2 had mild inotropic support with dopamine; group 3 had high-dose inotropic support with adrenalin and dopamine. Thirty-eight patients in group 1 (63%), 40 in group 2 (67%), and 32 in group 3 (53%) responded to one or two doses of diltiazem. There was no difference between the groups in terms of the success rate of the treatment (p > 0.05). Additional procedures were needed in 70 patients including cardioversion in 20 (12 in group 1, 8 in group 2). Mean cardiac index was significantly increased and mean pulmonary artery pressure was significantly decreased in all three groups after diltiazem treatment. After the first dose of diltiazem (0.25 mg·kg−1), the mean heart rate decreased from 141.5mg·kg−1 ± 3.8, 136.9 ± 8.5, and 140.2 ± 4.7 to 118.2 ± 5.1, 101.2 ± 6.7, and 105.6 ± 16.8 in groups 1, 2, and 3, respectively. The maximum decrease was seen after 5 minutes. After the second dose of diltiazem (0.35 mg·kg−1), although mean heart rates were not significantly decreased, 45% of group 1, 44% of group 2, and 46% of group 3 patients who did not respond to the first dose of diltiazem, converted to sinus rhythm. In the early postoperative period after coronary artery bypass graft surgery, diltiazem was of benefit in the treatment of supraventricular tachycardia and atrial fibrillation or flutter. This treatment may be especially useful in patients who are in poor hemodynamic condition.

Current role of pharmacologic therapy for patients with paroxysmal supraventricular tachycardia

Intravenous antiarrhythmic drugs will continue to have an important role in the acute management of SVT. Long-term antiarrhythmic drug therapy is often effective in preventing or reducing frequency and severity of arrhythmic episodes. The cost, adverse effects, and inconvenience of long-term drug therapy will result in the increasing use of curative ablation for most individuals with problematic SVT.

Management of paroxysmal atrioventricular nodal reentrant tachycardia in the critically ill surgical patient

OBJECTIVES

Paroxysmal atrioventricular nodal reentrant tachycardia is an infrequently encountered supraventricular arrhythmia that continues to present difficult management problems in the critically ill surgical patient. The purpose of this study was to evaluate the efficacy of a new treatment algorithm involving the sequential administration of different classes of antiarrhythmic agents until conversion to sinus rhythm was achieved.

DESIGN

Nonrandomized, consecutive, protocol-driven descriptive cohort.

SETTING

University hospital surgical and trauma intensive care unit (ICU).

PATIENTS

During an 11-month period, we prospectively evaluated all hemodynamically stable patients who sustained new-onset atrioventricular nodal reentrant tachycardia.

INTERVENTIONS

Vagal maneuver, followed by the rapid, sequential infusion of antiarrhythmic agents (i.e., adenosine, verapamil, and esmolol, respectively) until the arrhythmia was terminated.

MEASUREMENTS AND MAIN RESULTS

Twenty-seven patients (4% of all admissions) were evaluated, including 16 trauma patients (injury Severity Score of 20 +/- 8) and 11 general surgical patients (Acute Physiology and Chronic Health Evaluation II score of 17 +/- 7). Time from ICU admission to onset of atrioventricular nodal reentrant tachycardia was 4.5 +/- 5 days (median 2.5). Arrhythmia termination was achieved in all patients within minutes (mean 13 +/- 10 [SD]). Incremental sequential adenosine administration alone, however, was successful in affecting conversion to sinus rhythm in only 44% of initial episodes of atrioventricular nodal reentrant tachycardia (95% confidence interval 21% to 67%). A total of 14 (52%) patients developed 38 relapses of paroxysmal supraventricular tachycardia in the ICU after initial conversion to sinus rhythm. These relapses required additional antiarrhythmic therapy. Adenosine was only effective in 34% of the relapses (95% confidence interval 17% to 53%). Seven (50%) of these 14 patients developed multiple relapses. However, only two patients were receiving suppressive calcium-channel or beta-adrenergic receptor blockade at the time of relapse.

CONCLUSIONS

The use of a multiagent algorithm was effective for the initial conversion of new-onset atrioventricular nodal reentrant tachycardia to sinus rhythm in critically ill surgical and trauma patients. This preliminary report suggests that adenosine has marginal efficacy in the critically ill surgical or trauma patient. Given the high frequency of relapses, regardless of the agents used to achieve initial control, suppression therapy for the arrhythmia during the period of maximal cardiovascular stress is essential.

Safety and efficacy of intravenous diltiazem in atrial fibrillation or atrial flutter

This study examines the efficacy of various doses of intravenous diltiazem to control the ventricular response during atrial fibrillation or atrial flutter. Control of the ventricular response of patients with atrial fibrillation and a rapid ventricular response can provide patients with relief of symptoms and improve hemodynamics. Eighty-four consecutive patients with atrial fibrillation or atrial flutter, or both, received an intravenous bolus dose of diltiazem followed by a continuous infusion of diltiazem at 5, 10, and 15 mg/hour. The mean ventricular response and blood pressure were monitored. Overall, 94% of patients (79 of 84) responded to the bolus dose with a > 20% reduction in heart rate from baseline, a conversion to sinus rhythm, or a heart rate < 100 beats/min. Seventy-eight patients received the continuous infusion. After 10 hours of infusion, 47% of patients (confidence interval [CI]: 36%, 59%) had maintained response with the 5 mg/hour infusion, 68% (CI: 57%, 79%) maintained response after the infusion was titrated to 10 mg/hour, and 76% (CI: 66%, 85%) after titration from the 5 and 10 mg/hour infusion to the 15 mg/hour dose. For the 3 diltiazem infusions studied, mean (+/- SD) heart rate was reduced from a baseline value of 144 +/- 14 beats/min to 98 +/- 19, 107 +/- 25, 107 +/- 22, 101 +/- 22, 91 +/- 17, and 88 +/- 18 beats/min at infusion times 0, 1, 2, 4, 8, and 10 hours, respectively. By the end of the infusion, 18% of patients (14 of 78) had conversion to sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of KRN2391 on canine ventricular arrhythmia models

1. KRN2391 (3-30 micrograms/kg, i.v.) produced a decrease in mean blood pressure (MBP) with concomitant increase in heart rate (HR) and change in electrocardiogram (ECG) such as the shortening of PP and PQ intervals and the prolongation of QTc and these changes in HR and ECG were attenuated by pretreatment with propranolol (1 mg/kg) in normal dogs. 2. KRN2391 at 30 micrograms/kg induces neither suppression nor aggravation of ventricular arrhythmias caused by adrenaline and digitalis. 3. In two-stage coronary ligation-induced arrhythmia, KRN2391 inhibited arrhythmia at 48 hr. 4. These results suggest that KRN2391 may be effective on arrhythmia related to ischemia. In addition, it is considered that arrhythmia is not induced even by a high dose of KRN2391 in the normal condition.