Efficacy and safety of midodrine hydrochloride in patients with refractory vasovagal syncope.
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Adrenergic alpha-Agonists↗
Biomedical subjects
D G Benditt
Publications and source records attributed to D G Benditt.
Atrioventricular dissociation exacerbating posturally-induced syncope.
We report a case of an 85-year-old patient with posturally-induced syncope in whom symptoms were reproduced during tilt table testing in conjunction with development of an accelerated junctional rhythm with isorhythmic atrio-ventricular (AV) dissociation. That loss of AV synchrony was crucial to development of hypotension and syncope was demonstrated during electrophysiologic testing in which both an accelerated junctional rhythm and an inducible atypical AV nodal re-entrant tachycardia (AVNRT) were induced. The accelerated junctional rhythm was accompanied by moderate hypotension with the patient in the supine posture, whereas blood pressure was well maintained during atypical AVNRT despite a much faster ventricular rate. Thus, symptomatic hypotension due to AV dissociation, presumably the result of transient autonomic disturbance, may be another manifestation of neurally-mediated syncope.
Aged↗
Central clinical research issues in electrophysiology: report of the NASPE Committee.
This article contains the results of an attempt by appointed members of the North American Society of Pacing and Electrophysiology to define the research frontier in electrophysiology and suggest areas of study as an aid in setting the research agenda.
Arrhythmias, Cardiac↗
Unusual cause of supraventricular tachycardia after acute myocardial infarction.
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Adult↗
Syncope in pharmacologically unmasked Brugada syndrome: indication for an implantable defibrillator or an unresolved dilemma?
A 30-year-old Caucasian male was referred for evaluation of a 2-year history of recurrent post-exertion lightheadedness and near syncopal spells in the setting of a family history of unexplained sudden cardiac death. Cardiac evaluation demonstrated normal heart structure, but the 12-lead surface ECG was suggestive of but not diagnostic of Brugada syndrome. An exercise stress test reproduced the patient's usual symptoms during the recovery period, and was consistent with a typical vasovagal faint. The same symptoms were observed during a head-up tilt table test. However, given the family history and ECG, pharmacological testing with procainamide, isoprenaline and metoprolol, as well as programmed ventricular stimulation, were undertaken. Pharmacological provocation further supported a diagnosis of Brugada syndrome, whereas programmed ventricular stimulation was considered non-diagnostic regarding ventricular tachyarrhythmia susceptibility. Consequently, despite ECG and pharmacological findings suggestive of Brugada syndrome, there appeared to be sufficient evidence to believe that this patient's symptoms were the result of neurally mediated syncope and not due to ventricular tachyarrhythmias. The patient was treated with midodrine, and has remained symptom-free for 16 months. Thus, given the frequency with which vasovagal syncope occurs in young patients, its occurrence is not unexpected in individuals with concomitant diagnoses such as Brugada syndrome. In as much as current recommendations favour implantable defibrillators in symptomatic Brugada syndrome, the identification of other causes of syncope in such patients poses an uncomfortable, and currently unsettled dilemma.
Adult↗
Left ventricular-based pacing in patients with chronic heart failure: comparison of acute hemodynamic benefits according to underlying heart disease.
BACKGROUND: Acute left ventricular-based pacing has been shown to improve hemodynamics in patients with severe heart failure and left bundle branch block (LBBB). However, it is not known whether the cause of the underlying heart disease influences the potential effect of left ventricular-based pacing. OBJECTIVES: The aim of this study was to determine whether beneficial hemodynamic effects of acute left ventricular-based pacing in severe chronic heart failure are dependent on underlying heart disease. METHODS: After coronary angiography, patients with severe heart failure and LBBB were separated into two groups: dilated (25 patients; 20 male) and ischemic cardiomyopathy (21 patients; 20 male). Hemodynamic parameters were evaluated at baseline and during left ventricular-based pacing. RESULTS: Improvement in hemodynamic parameters were similar in both groups, during acute left ventricular pacing (changes expressed in percentage): pulmonary capillary wedge pressure, -16+/-15% vs. -14+/-10%; V wave amplitude, -25+/-18% vs. -21+/-17%; and biventricular pacing, -15+/-15% vs. -11+/-11% and -23+/-18% vs. -16+/-18%, respectively. CONCLUSION: Underlying heart disease does not influence the response to acute left ventricular-based pacing in patients with severe heart failure and LBBB. This finding provides support for including all patients with enlarged heart and heart failure in future studies evaluating left ventricular-based pacing.
Aged↗
Atrial fibrillation: defining potential curative ablation targets.
The concept that atrial fibrillation (or at least certain forms of the arrhythmia) may be amenable to reversal or amelioration by transcatheter ablation techniques has become increasingly accepted in recent years. As yet, however, the techniques being studied for ablation of atrial fibrillation address neither known critical anatomic elements nor well defined electrophysiologic markers. The approaches, although essentially empirical, are conceptually based on the 'multiple wavelet' or 'focal origin' hypotheses. To date, addressing 'focal origin' atrial fibrillation by transcatheter ablation has been the more encouraging. However, as technology evolves, both in terms of catheter design and possibly endocardial mapping techniques, approaches to wavelet or rotor mechanisms may become similarly effective. This communication examines concepts regarding the manner in which atrial fibrillation is initiated and maintained. The goals are to better understand the encouraging success of empirical ablation methods, and possibly derive insights which may help refine ablation targeting in the future.
Atrial Fibrillation↗
Respiratory changes during the evolving vasovagal faint: physiologic and clinical implications.
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Biomarkers↗
Pharmacotherapy of neurally mediated syncope.
A wide variety of pharmacological agents are currently used for prevention of recurrent neurally mediated syncope, especially the vasovagal faint. None, however, have unequivocally proven long-term effectiveness based on adequate randomized clinical trials. At the present time, beta-adrenergic receptor blockade, along with agents that increase central volume (eg, fludrocortisone, electrolyte-containing beverages), appear to be favored treatment options. The antiarrhythmic agent disopyramide and various serotonin reuptake blockers have also been reported to be beneficial. Finally, vasoconstrictor agents such as midodrine offer promise and remain the subject of clinical study. Ultimately, though, detailed study of the pathophysiology of these syncopal disorders and more aggressive pursuit of carefully designed placebo-controlled treatment studies are essential if pharmacological prevention of recurrent neurally mediated syncope is to be placed on a firm foundation.
Adrenergic beta-Antagonists↗
Living anatomy of the atrioventricular junctions. A guide to electrophysiologic mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrhythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE.
Current nomenclature for the atrioventricular (AV) junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, although the mouth of the coronary sinus is shown as being posterior. Although this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal reentry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. It proposes a new anatomically sound nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value for description of the AV junctions, establishing the principles of this new nomenclature.
Atrioventricular Node↗
Maintenance of sinus rhythm with oral d,l-sotalol therapy in patients with symptomatic atrial fibrillation and/or atrial flutter. d,l-Sotalol Atrial Fibrillation/Flutter Study Group.
Currently d,l-sotalol is widely used to prevent recurrence of atrial fibrillation and/or atrial flutter, although a randomized dose-response study has not previously been conducted to guide therapy for this indication. This study summarizes findings of a double-blind, placebo-controlled, multicenter, randomized trial evaluating the efficacy, safety, and dose-response relation of 3 fixed doses of d,l-sotalol (80, 120, and 160 mg twice daily) for the maintenance of sinus rhythm in 253 patients with atrial fibrillation and/or atrial flutter. All patients were in sinus rhythm at randomization. Treatment (69 patients on placebo, 59 on 80 mg, 63 on 120 mg, and 62 on 160 mg given twice daily) was continued for 12 months or until documented recurrence of symptomatic atrial fibrillation and/or flutter. Transtelephonic electrocardiographic monitoring was used to detect symptomatic recurrences. Demographic characteristics were not different in the 4 groups. Structural heart disease was present in 57% of patients. Patients with a history of heart failure were excluded. The time from randomization to symptomatic arrhythmia recurrence was significantly longer in the 2 higher d,l-sotalol dose groups than in the placebo group. The median times to recurrence were 27, 106, 229, and 175 days for the placebo, 80, 120, and 160 mg groups, respectively. There were no deaths or cases of torsade de pointes, sustained ventricular tachycardia, or ventricular fibrillation reported. Thus, d,l-sotalol appeared to be both safe and effective in maintaining sinus rhythm in patients with symptomatic atrial fibrillation and/or flutter. Further, the 120-mg twice daily dose appeared to provide the most favorable benefit and/or risk.
Anti-Arrhythmia Agents↗
Evaluation of left ventricular based pacing in patients with congestive heart failure and atrial fibrillation.
Acute hemodynamic data of left ventricular based pacing were assessed in 2 groups of patients with severe cardiac failure: 11 patients with atrial fibrillation and 17 patients with sinus rhythm. Both biventricular and left ventricular pacing significantly improved acute hemodynamic findings to a similar degree in both groups, suggesting that left ventricular based pacing may be beneficial in patients with severe cardiac failure regardless of whether or not they are in sinus rhythm.
Aged↗
Resumption of motor vehicle operation in vasovagal fainters.
This study surveyed current practice patterns with respect to the manner by which cardiac arrhythmia specialists advise patients with vasovagal syncope regarding resumption of motor vehicle operation. Among 66 physician-respondents from 9 countries, 98% indicated that they rely on tilt-table testing to establish a diagnosis, and, if an effective treatment is found based on serial tilt-table testing, they recommend a 6- to 7-week symptom-free waiting period before advising return to driving.
Attitude of Health Personnel↗
Cardiac pacing for prevention of vasovagal syncope.
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Adult↗
"Rate-drop response" cardiac pacing for vasovagal syncope. Rate-Drop Response Investigators Group.
Recent reports suggest that cardiac pacing incorporating a rate-drop response algorithm is associated with a reduction in the frequency of syncopal episodes in patients with apparent cardioinhibitory vasovagal syncope. The detection portion of the algorithm employs a programmable heart rate change-time duration "window" to both identify abrupt cardiac slowing suggestive of an imminent vasovagal event and trigger "high rate" pacing. The purpose of this study was to develop recommendations for programming the rate-drop response algorithm. Pacemaker programming, symptom status, and drug therapy were assessed retrospectively in 24 patients with recurrent vasovagal syncope of sufficient severity to warrant consideration of pacemaker treatment. In the 53 +/- 19 months prior to pacing, patients had experienced an approximate syncope burden of 1.2 events/month. During follow-up of 192 +/- 160 days, syncope recurred in 4 patients (approximate syncope burden, 0.3 events/month, p < 0.05 vs. pre-pacing), and pre-syncope in 5 patients. In these patients, rate-drop response parameters were initially set based on electrocardiographic and/or tilt-table recordings, and were re-programmed at least once in 14 (58%) individuals. A 20 beat/min window height (top rate minus bottom rate), a window width of 10 beats (61% of patients), and 2 or 3 confirmation beats (79% of patients) appeared to be appropriate in most patients. Treatment intervention rate was set to > 100 beats/min in 89% of patients, with a duration of 1 to 2 min in 79%. In conclusion, a narrow range of rate-drop response parameter settings appeared to be effective for most individuals in this group of highly symptomatic patients.
Adolescent↗
Generic antiarrhythmic drugs: what constitutes equivalency.
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Amiodarone↗
Living anatomy of the atrioventricular junctions. A guide to electrophysiological mapping. A Consensus Statement from the Cardiac Nomenclature Study Group, Working Group of Arrythmias, European Society of Cardiology, and the Task Force on Cardiac Nomenclature from NASPE. North American Society of Pacing and Electrophysiology.
Current nomenclature for atrioventricular junctions derives from a surgically distorted view, placing the valvar rings and the triangle of Koch in a single plane with antero-posterior and right-left lateral coordinates. Within this convention, the aorta is considered to occupy an anterior position, while the mouth of the coronary sinus is shown as being posterior. While this nomenclature has served its purpose for the description and treatment of arrhythmias dependent on accessory pathways and atrioventricular nodal re-entry, it is less than satisfactory for the description of atrial and ventricular mapping. To correct these deficiencies, a consensus document has been prepared by experts from the Working Group of Arrhythmias of the European Society of Cardiology, and the North American Society of Pacing and Electrophysiology. It proposes a new, anatomically sound, nomenclature that will be applicable to all chambers of the heart. In this report, we discuss its value as regards the description of the atrioventricular junctions, establishing the principles of this new nomenclature.
Atrioventricular Node↗
Prehospital discharge defibrillation testing in ICD recipients: a prospective study based on cost analysis.
Prehospital discharge defibrillation testing is often performed to verify the function of newly implanted cardioverter defibrillators (ICDs). To determine whether elimination of predischarge testing could reduce costs without placing patients at additional risk, 31 patients were randomized in this prospective clinical evaluation to either receive or not receive a predischarge ICD defibrillation test. Expenses associated with postimplant care was the primary endpoint. All patients underwent induction of ventricular fibrillation after 6 months to evaluate ICD function. The groups were well matched in terms of patient characteristics, initial lead implant parameters, and defibrillation thresholds. Elimination of prehospital discharge testing resulted in a savings of $1,800/patient after 6 months, with no difference between groups in terms of ICD complication rates or unanticipated hospital admissions. Further studies are needed to better define the most appropriate time to assess defibrillation thresholds in the first year after implantation.
Aged↗