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Biomedical subjects

J A Reiffel

Publications and source records attributed to J A Reiffel.

At least 19 recordsLinked to original sources
PubMed1994

Electrophysiological testing of sinus node function: diagnostic and prognostic application-including updated information from sinus node electrograms.

Sinus node function, including automaticity, conduction, and refractoriness, can be studied in the human electrophysiology laboratory. This review details the current methods used for such studies and discusses their clinical value. Of special emphasis in this article is the role of sinus node electrography in the clinical laboratory. Included also is an update of the data relating the duration of sinus node depolarization as measure on sinus node electrograms to other parameters that assess sinus node function as well as data supporting the direct relationship between the duration of the sinus node depolarization as the severity of sinus node dysfunction.

Action Potentials↗
PubMed1991

Optimum duration of transtelephonic ECG monitoring when used for transient symptomatic event detection.

Transtelephonic electrocardiographic monitoring (TTM) has been used for postpacemaker follow-up study, postmyocardial infarction monitoring, and transient symptomatic event detection (TSED). For postpacemaker follow-up study, TTM is continued indefinitely. For postmyocardial infarction monitoring, TTM is continued for 1 year or more. For TSED, the appropriate duration for TTM has not yet been adequately assessed. Accordingly, the authors determined the yield, by week, of TTM for TSED. Five thousand fifty-two patients who made 20,590 calls were analyzed for this investigation. Ninety-five percent of patients making symptomatic calls or making a call in which an arrhythmia was documented did so within 5 weeks. Shorter periods would sacrifice yield, longer periods may not be cost-effective.

Arrhythmias, Cardiac↗
PubMed1989

Efficacy, safety, and tolerance of d-sotalol in patients with refractory supraventricular tachyarrhythmias.

The efficacy, safety, and electrophysiologic effects of intravenous and oral d-sotalol, an investigational class III antiarrhythmic agent, are not yet well characterized. We evaluated the electrophysiologic, antiarrhythmic, and hemodynamic effects of d-sotalol infusion (1.5 to 2.75 mg/kg) and of chronic oral therapy (200 to 400 mg bid) in 10 patients with chronic, paroxysmal supraventricular tachyarrhythmias refractory to 5 +/- 2 standard agents. Four patients had paroxysmal supraventricular tachycardia (PSVT), four had paroxysmal atrial fibrillation, two had atrial flutter, and one had nonparoxysmal reciprocating junctional tachycardia (NPRJT). PSVT was inducible or spontaneously present in 4 of 4 before d-sotalol. After intravenous d-sotalol PSVT was noninducible in three patients and slowed by 40% in one. Atrial fibrillation was inducible or spontaneously present in 4 of 4 before therapy. After intravenous d-sotalol, one became noninducible, and three achieved rate-slowing (the mean falling from 69 to 61 bpm). In one patient, atrial flutter became noninducible; in another, d-sotalol slowed the rate of atrial flutter by 28%. D-sotalol restored sinus rhythm in the patient with NPRJT. Intravenous d-sotalol increased the sinus cycle length; the QTc, PR, and AH intervals; and the AV nodal functional refractory period, the AV nodal effective refractory period; and the right ventricular effective refractory period significantly. The atrial effective refractory period, sinoatrial conduction time, and corrected sinus recovery time tended to increase, but did not reach statistical significance. The QRS, PA, and HV intervals did not change. Mean BP fell 13.4 +/- 9.2% after intravenous d-sotalol, but no adverse symptoms developed.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1989

The duration of the sinus node depolarization on transvenous sinus node electrograms can identify sinus node dysfunction and can suggest its severity.

Catheter recorded sinus node electrograms (SNE) allow visualization of sinus node depolarization (SND). The SND on a bipolar SNE is probably a composite reflecting both P cell action potentials and intranodal conduction. Reduced rate of rise, prolonged action potential duration and/or delayed intranodal conduction might each prolong the SND duration. Thus, SND duration might reflect several clinically important sinus node abnormalities and aid in the recognition of sick sinus syndrome. Moreover, the SND duration might be expected to be the most prolonged in patients with the most severe sinus node dysfunction. To test this hypothesis, we determined SND duration in 32 patients and correlated it with the presence or absence of evidence of sinus node dysfunction by ECG and/or electrophysiological (EP) studies. Seven patients had no sinus node dysfunction (group 1); 10 patients had mild sinus node dysfunction (a single abnormality of corrected sinus recovery time, sinoatrial conduction time, PCLp, or ECG) (group 2); and 15 patients had two or more abnormalities electrocardiographically and/or by EP testing (group 3). The SND duration (mean/range) was 129/95-190 msec in group 1, 151/95-225 msec in group 2, and 196/140-260 msec in group 3. In group 3, three patients who had ECG evidence of sick sinus syndrome and abnormalities on all three EP parameters, the SND duration was 230/200-260 msec. Carotid sinus massage (CSM) was found to prolong the SND duration in 5/7 patients in groups 2 and 3 where the SND could be measured both before and during CSM. CSM was necessary to allow visualization of the SND in 3/7 group 1 patients; thus their recorded values may be falsely long. The normal with a SND duration greater than 150 (190 msec) had it measured during CSM. None of the group three patients with SND duration less than msec had a prolonged CSRT or ECG evidence of sick sinus syndrome. Literature review revealed SNE recordings on 18 patients with sick sinus syndrome on which the SND duration could be measured; it was greater than or equal to 200 msec in all. Thus, the SND duration appears to reflect the presence and degree of sinus node dysfunction. Sinus node dysfunction appears unlikely if the SND duration is less than 150 msec and is likely to be severe if the SND duration is greater than 200 msec.

Adult↗
PubMed1989

Relation of baseline characteristics to suppression of ventricular arrhythmias during placebo and active antiarrhythmic therapy in patients after myocardial infarction.

In the Cardiac Arrhythmia Pilot Study (CAPS), patients early (6-60 days) after acute myocardial infarction (MI) with ventricular premature complexes (VPCs) of over 10 per hour were randomized to receive, unaware, therapy with one of four antiarrhythmic drugs (n = 402) or placebo (n = 100). Treatment success was defined as 70% or more decrease in VPC rate and 90% or more decrease in VPC runs. If the first active drug was ineffective, a second drug was given. If placebo was ineffective, a second placebo was given. To determine whether or not baseline clinical characteristics predict the response to antiarrhythmic therapy, 10 baseline variables were selected for investigation: age, prior MI, time from CAPS MI to randomization, ejection fraction, baseline VPC frequency, presence of runs (greater than or equal to 3 consecutive VPCs, greater than or equal to 100 beats/min), beta-blocker therapy, digitalis therapy, MI transmurality, and MI location. At the end of the first drug treatment, apparent treatment success in patients receiving placebo was associated on univariate analysis with absence of prior MI, with trends for younger age and Q wave MI, whereas in patients receiving active therapies, higher ejection fraction and younger age were associated with better suppression. In the encainide and flecainide treatments, where the greatest response was observed, absence of prior MI, higher ejection fraction, and younger age were associated with more successful treatment. In a multivariate analysis with these variables, ejection fraction and age remained significant for all active therapies, absence of prior MI and ejection fraction remained significant in the encainide and flecainide treatments, and absence of prior MI in the placebo treatment. Few variables except ejection fraction were associated with VPC suppression during the 1-year follow-up, and only lower ejection fraction and older age related to loss of long-term suppression. Thus, there are only a few independent baseline clinical variables (notably, ejection fraction) that substantially affect antiarrhythmic drug efficacy in suppressing VPCs in patients early after MI. Some variables, however, may be associated with spontaneous arrhythmia variability, leading to an apparent (placebo) response. These findings will be helpful in designing and interpreting treatment studies in patients after MI.

Anilides↗
PubMed1986

Phase analysis of gated blood pool scintigraphic images to localize bypass tracts in Wolff-Parkinson-White syndrome.

The ability of radionuclide techniques to localize bypass tracts in patients with Wolff-Parkinson-White syndrome to sites around the atrioventricular (AV) ring using a three view triangulation method was investigated. In 17 patients with Wolff-Parkinson-White syndrome, phase images were generated from gated blood pool scans using the first Fourier harmonic of the time-activity curve of each pixel. In addition, the difference between left and right ventricular mean phase angles was calculated for each patient and for 13 control subjects. Bypass tracts were localized to one or more sites on a 10 site grid schematically superimposed on the AV ring (Duke grid) by electrophysiologic study in all patients and by intraoperative mapping in 7 of the 17 patients. These same 10 anatomic sites were projected onto three scintigraphic views and the site of earliest ventricular phase angle was located in each view. The 10 sites around the AV ring were divided into two anatomic groups: free wall and septal/paraseptal. Phase image locations correlated with electrophysiologic locations within one grid site in 11 of 11 patients with free wall tracts and were confirmed at surgery in 5 of the 11. In five of six patients with septal/paraseptal tracts, electrophysiologic study could not localize the bypass tract to one site, whereas phase images localized two of the five as free wall adjacent to the septum, one as paraseptal and two as true posteroseptal. One posteroseptal site was confirmed at surgery. In one patient, in whom phase image analysis and electrophysiologic study showed different sites, existence of both tracts was confirmed at surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Electrophysiologic evaluation of sinus node function.

Sinus node dysfunction can be evaluated by invasive and noninvasive means. In this article, invasive testing of sinus node function and its clinical utility are reviewed. Sinus recovery times, sinoatrial conduction times, sinus node refractory periods, and sinus node electrograms are all reviewed in detail, with regard to both theory and practice.

Electrophysiology↗
PubMed1985

Nitrate therapy for angina pectoris. Current concepts about mechanism of action and evaluation of currently available preparations.

Nitrates are presently used in the therapy for angina pectoris. They have both direct coronary vascular and indirect systemic effects; each appears to contribute to their anti-anginal efficacy. The various nitrate preparations, including the newer preparations recently made clinically available, have varying utilities in the relief of acute ischemic pain or for anginal prophylaxis. Nitrate tolerance and dependence are proved phenomena, yet their impact on the clinical usage of nitrates is not clearly defined. The utility of nitrates, including intravenous nitroglycerin, in the treatment of unstable angina and vasospastic angina is well documented. Their efficacy compared with that of calcium channel blockers is still being investigated. The reported adverse effects of nitrates are few, despite their many years of usage in clinical medicine.

Administration, Oral↗
PubMed1985

Electrophysiologic testing in patients with recurrent syncope: are results predicted by prior ambulatory monitoring?

Syncope is a common medical problem which can result from many etiologies, including cardiac dysrhythmias. Because ambulatory monitoring usually fails to capture a syncopal episode, electrophysiologic testing has been used to elucidate dysrhythmic mechanisms in patients with recurrent syncope. To assess whether findings on ambulatory monitoring not obtained during syncope can be used to indicate the results which are found on electrophysiologic testing in patients with recurrent syncope, we reviewed the ambulatory monitoring records of 59 such patients referred for electrophysiologic testing. Although 29 patients had abnormalities on electrophysiologic testing, 13 of which were severe, in only six were the findings suggested by the abnormalities recorded during ambulatory monitoring. Twenty-one patients actually had concordance between electrophysiologic testing and ambulatory monitoring results, but in 15 of the 21 results of both tests were normal. Severe abnormalities were more frequently detected in our patient population by electrophysiologic testing than by ambulatory monitoring, especially if patients had organic heart disease.

Adolescent↗
PubMed1985

Sinus node echoes and concealed concealed conduction: additional sinus node phenomena confirmed in man by direct sinus node electrography.

Direct sinus node electrography has been previously used to assess several aspects of sinus node physiology: sinus node pauses, overdrive suppression, sinoatrial entrance block. This report presents data in which sinus node electrograms confirm two additional physiologic phenomena in man: concealed conduction in the sinoatrial junction and sinus node reentry. These findings verify the presence of previously suspected phenomena by careful deductive analysis of electrocardiographic and electrographic tracings.

Adult↗