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Biomedical subjects

M Fromer

Publications and source records attributed to M Fromer.

66 records · Page 4Linked to original sources
PubMed1988

Tachycardia cycle length and maximum capacity of anterograde and retrograde atrioventricular conduction in paroxysmal supraventricular tachycardia.

Anterograde and retrograde pathways are the two major components of the reentry circuit in patients with paroxysmal supraventricular reentrant tachycardias. Therefore, the capacity of each pathway to maintain 1:1 conduction would be expected to determine the cycle length (CL) of the tachycardia. In this study, the possible relationship between the CL of reentrant tachycardia and the maximum capacities of anterograde and retrograde conduction in the maintenance of a 1:1 response during atrial and ventricular pacing were examined. This relationship was analyzed in 26 patients with orthodromic reentrant tachycardia due to Wolff-Parkinson-White syndrome (group 1) and compared with that in 26 patients with atrioventricular nodal reentrant tachycardia (group 2). There were no statistically significant differences between the two groups in the shortest tachycardia CLs (mean +/- SD, 325 +/- 44 versus 329 +/- 52 ms); in the shortest ventricular pacing CLs with 1:1 response (314 +/- 63 versus 319 +/- 38 ms); nor in the CLs that produced retrograde atrioventricular block (306 +/- 62 versus 301 +/- 37 ms). In contrast, the longest atrial pacing CL that produced Wenckebach's phenomenon and the shortest atrial pacing CL with 1:1 response were significantly shorter for group 1 than for group 2 patients (290 +/- 38 versus 390 +/- 88 ms, P less than 0.001) and (305 +/- 38 versus 406 +/- 90 ms, P less than 0.001), respectively. It was concluded that the CL of orthodromic tachycardia can best be predicted from the shortest atrial pacing CL that maintains 1:1 anterograde conduction via the normal pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

Efficacy and safety of intravenous and oral diltiazem for Wolff-Parkinson-White syndrome.

The electrophysiologic effects and safety of diltiazem administered either intravenously or orally were studied in 14 patients with Wolff-Parkinson-White syndrome during orthodromic reentrant tachycardia and atrial fibrillation (AF). Anterograde and retrograde effective refractory periods of the accessory pathway did not change significantly from baseline during either i.v. or oral administration. Administration by either route prevented induction of sustained reentrant tachycardia in 8 patients. In 6 patients, the reentrant tachycardia was either nonsustained (2 patients) or sustained at much slower rates than the baseline rates (mean +/- standard deviation, baseline, 290 +/- 41 ms; i.v., 355 +/- 40 ms [p less than 0.001]; and oral, 377 +/- 33 ms [p less than 0.001]). In these patients anterograde atrioventricular conduction was prolonged significantly from the mean baseline value of 163 +/- 36 ms to 212 +/- 35 ms with i.v. administration (p less than 0.005) and 225 +/- 33 ms with oral administration (p less than 0.005). Retrograde conduction via the accessory pathway did not change significantly after administration of diltiazem. The shortest preexcited RR intervals during AF were significantly reduced during i.v. but not during oral administration: control, 327 +/- 47 ms; i.v., 270 +/- 28 ms (p less than 0.001); and oral, 323 +/- 44 ms (difference not significant). In 5 patients AF was sustained for a mean of 20 minutes after i.v. and for 12 minutes after oral administration (p less than 0.20), compared with a baseline mean value of 0.83 minute.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1985

[Effect of heart rate on the refractory period of the accessory atrioventricular pathway in Wolff-Parkinson-White syndrome].

Electrophysiologic investigations have been performed in 13 patients with symptomatic WPW syndrome. The effective refractory periods of the right atrium (AERP), the antegrade effective refractory periods of the accessory pathway (AP-ERP) during sinus rhythm and at different cycle length, the shortest RR-intervals with preexcitation during atrial fibrillation (RR-AF) and the appearance of block in the AP during incremental atrial pacing have been measured. The data collected during sinus rythm (SR) and at different pacing rates were analyzed and compared. During SR (cycle length 851 +/- 157 ms) AERP measured 263 +/- 56 ms and AP-ERP 309 +/- 55 ms. At a cycle length of 450-550 ms, AERP measured 221 +/- 36 ms and AP-ERP 250 +/- 35 ms, and at a cycle length of 400-450 ms AERP was 213 +/- 35 ms and AP-ERP 230 +/- 42 ms. The mean RR-AF was 253 +/- 35 ms. A significant correlation was found between AERP and AP-RP at a cycle length of 400-450 ms (r = 0.92), but not between AP-ERP and RR-AF at any cycle length. Block in the AP occurred at a mean pacing cycle length of 280 +/- 42 ms. The electrophysiologic measurements of patients with syncope did not differ from patients without syncope in our group. The data show that in patients with a long AP-ERP (greater than 290 ms) during SR an increase of the heart rate leads to a significant shortening of the AP-ERP. No relevant correlation was found between AP-ERP and mean RR-AF. Patients with AP-ERP shorter than RR-AF appear to be a high-risk subgroup for ventricular fibrillation during AF.

Adolescent↗
PubMed1983

[Considerations on the therapy with physiologic pacemakers].

Physiologic pacemakers offer hemodynamic benefits in comparison to conventional pacing, but demand more detailed diagnosis of the arrhythmia in need of treatment. In order to prevent endless loop tachycardias, ventriculoatrial conduction must be analyzed. Normal sinus node and atrial function should be confirmed in atrial triggered ventricular stimulation. The techniques and values of preimplantation investigations, including intracardiac electrophysiological procedures, are discussed.

Atropine↗
PubMed1983

[Binodal disease: diseased sinus node and atrioventricular block].

Atrioventricular (AV) conduction disturbances in patients (pts) with sick sinus syndrome (SSS) are well known, but sinus node function (SNF) in AV block is not well documented. We therefore performed electrophysiological tests to evaluate SNF in 30 pts with high-degree AV block (group 1) and AV conduction in 15 pts with SSS (group 1). These measurements were repeated after vagolysis with atropine in group 2. In group 1 ergometry was performed if the electrophysiological SNF tests were abnormal. Results (mean +/- 1 SD) for group 1 were: sinus node recovery time (SNRT) 1184 +/- 473 ms, corrected SNRT (cSNRT) 337 +/- 394 ms. In 3 pts SNRT or cSNRT was abnormal. In these 3 pts the response of sinus rate to exercise was insufficient. In group 2 SNRT before and after atropine was 2345 +/- 822 ms and 1558 +/- 815 ms respectively (p less than 0.05), cSNRT 1285 +/- 965 ms and 954 +/- 832 ms (n.s.), sinoatrial conduction time 319 +/- 283 ms and 150 +/- 149 ms (n.s.), and Wenckebach point 532 +/- 178 ms and 383 +/- 68 ms (p less than 0.01). His-ventricle time was 48 +/- 5.8 ms. In 6 of these 15 pts impaired AV-conduction was present (defined as Wenckebach point below 500 ms), but normalized in 4 pts after atropine. We postulate that persistence of abnormal SNF and AV conduction after vagolysis is an argument for organic binodal disease. This occurs with equal frequency in both groups in about 10% of patients. Increased vagal tone is common in SSS and uncommon in AV block. In patients with SSS the frequent additional AV conduction delay must be taken into consideration when atrial pacing is considered.

Adult↗
PubMed1979

Progression of mild mitral stenosis and incidence of restenosis after open commissurotomy: a study using echocardiography.

Thirteen patients with mild mitral stenosis and 21 asymptomatic patients after commissurotomy were studied by echocardiography in order to assess the rate of progression of mitral stenosis and the incidence of restenosis after successful open mitral commissurotomy. In the group with mitral stenosis there was a decrease of the diastolic closing velocity (E-F slope) from 35.7 to 29.5 mm./sec. (p less than 0.0005) over a period of 37 months. In 23% of the patients the stenosis increased significantly (p less than 0.0005) by echocardiographic parameters. Forty-eight months after commissurotomy we noted a significant over-all slowing of the diastolic closing velocity (from 52.6 to 44.8 mm./sec., p less than 0.0005) and a decrease of the mitral valve closure index DE/MAIC (from 1.7 to 1.5, p less than 0.0025). Five of 21 patients (24%) showed a change in one or both of these parameters which was greater than 2 standard deviations of the mean change. Based on echocardiographic criteria, we conclude that patients with mild mitral stenosis and asymptomatic patients following successful commissurotomy need only be checked approximately every 3 years.

Adult↗
PubMedDate not supplied

Subband modeling of the human cardiovascular system: new insights into cardiovascular regulation.

We present a new approach to cardiovascular analysis based on a well-known signal processing technique, namely, the frequency subband decomposition. The subbands are chosen in accordance with physiological standards: (1) 0-0.04 Hz, (2) 0.04-0.15 Hz, (3) 0.15-0.4 Hz. It is shown that such a pre-processing drastically improves the accuracy of the analysis and introduces a new direction in the understanding of the relationships between cardiovascular signals.

Adult↗
PubMedDate not supplied

Termination of sustained ventricular tachycardia with a new antitachycardia pacemaker: role of the nonautomatic mode to follow pacemaker function.

The use of an antitachycardia pacemaker for the treatment of recurrent, drug resistant nonsyncopal sustained ventricular tachycardia in a 28-year-old patient is described. The report emphasizes the role of electrocardiographic recording during manual activation of the tachycardia response in an outpatient setting. The follow-up covers 12 months with 26 spontaneous tachycardia episodes forcing the patient to go to an emergency room to monitor tachycardia termination. Mean ventricular tachycardia cycle length was 340 +/- 21 ms. Tachycardias were terminated either by the primary or secondary modality without acceleration or degeneration to ventricular fibrillation. Thus, it was possible to assess the efficacy and the safety of the termination programs. Unlike during intensive in-hospital testing, restoration of stable sinus rhythm was complicated by re-emergence of ventricular tachycardia. It is concluded that manual activation with medical supervision provides safe management of selected patients with ventricular tachycardia. However, in-hospital testing overestimated, in this case, the efficacy of tachycardia response modalities to terminate spontaneous tachycardia episodes. The customization of an antitachycardia pacemaker with an automatic implantable cardioverter/defibrillator may increase the quality of life as it would allow switching to automatic pace termination.

Adult↗