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Biomedical subjects

M Matas

Publications and source records attributed to M Matas.

At least 37 records · Page 2Linked to original sources
PubMed1998

Radiofrequency ablation of anteroseptal, para-Hisian, and mid-septal accessory pathways using a simplified femoral approach.

Feasibility of RF ablation using a simplified two-catheter technique from a femoral approach was studied in 97 consecutive patients with a manifest or concealed accessory pathway located at the anteroseptal, mid-septal, and para-Hisian areas. RF was applied at the site with the shortest V-delta interval or the earliest retrograde atrial activation during orthodromic tachycardia or right ventricular pacing. Ablation was initially successful in 88 of 97 patients (91%). Success rate was 94% (16/17) for anteroseptal, 94% (39/43) for para-Hisian, and 89% (33/37) for mid-septal accessory pathways, without differences between manifest and concealed pathways for any of the locations. Mean number of RF pulses was 8 +/- 5 for anteroseptal, 6 +/- 6 for mid-septal, and 12 +/- 13 for para-Hisian accessory pathways. Two patients (2%) required implantation of a permanent pacemaker for complete AV block. At a mean follow-up of 27 +/- 14 months, four patients with previous manifest preexcitation experienced resumption of intermittent preexcitation, but only one required a second successful procedure for recurrence of palpitations. RF ablation can be used effectively and without impairment of normal AV conduction in the majority of patients with anteroseptal, para-Hisian, and mid-septal accessory pathways using a simplified two-catheter technique from a femoral approach.

Adult↗
PubMed1998

Enhanced detection criteria in implantable defibrillators.

INTRODUCTION: Enhanced detection criteria in third-generation implantable defibrillators have been implemented to avoid inappropriate therapy of fast supraventricular arrhythmias. We prospectively analyzed the use of these criteria in patients with an implantable defibrillator with electrogram storing capability. METHODS AND RESULTS: In 82 consecutive patients with a Guidant-CPI implantable defibrillator, sudden onset > 9% and stability < 40 msec were systematically programmed in zone 1 of therapy together with a sustained rate duration security mechanism. All detected tachycardia episodes were analyzed. The study population consisted of 59 patients who had at least one episode of tachycardia detected in zone 1 during follow-up. The tachycardia rate in zone 1 never exceeded 210 beats/min. Twenty patients had no episodes during follow-up, and three patients had episodes detected exclusively in zone 2 of therapy. Supraventricular arrhythmias were detected frequently in the ventricular tachycardia zone (193 of 690 tachycardia episodes in 23 of 59 patients). Use of sudden onset was very effective in detecting sinus tachycardias (65 of 67 episodes), and stability was very useful in detecting atrial fibrillation (31 of 32 episodes). However, sensitivity in detecting ventricular tachycardia was only 90% (451 of 497 episodes). Application of the sustained rate duration criterion allowed appropriate treatment of all ventricular tachycardia episodes, increasing sensitivity to 100%; however, specificity in appropriate nontreatment of supraventricular decreased from 96% to 83%. Subsequent analysis of different algorithms applied to our data showed that sudden onset > 9% and stability < 40 msec was the algorithm with the best specificity and sensitivity. CONCLUSION: Programming sudden onset and stability detection criteria with a sustained rate duration safety net for triggering tachycardia therapy results in appropriate device management in most patients with supraventricular and slow (< 210 beats/min) ventricular tachycardias.

Algorithms↗
PubMed1997

Atrial fibrillation induced by atrioventricular nodal reentrant tachycardia.

In 4 patients with recurrent episodes of paroxysmal atrial fibrillation as the only documented arrhythmia, electrophysiologic study showed that atrial fibrillation originated after a very fast transition from atrioventricular nodal reentrant tachycardia. Recognition of atrioventricular nodal reentrant tachycardia as the triggering factor for atrial fibrillation has important therapeutic consequences.

Adult↗
PubMed1997

[Radiofrequency ablation of occult left accessory pathways without catheterization of the coronary sinus].

BACKGROUND: Radiofrequency catheter ablation of concealed left-sided accessory pathways conventionally implies the introduction of several catheters for the assessment of electrophysiological properties as well as for the localization of the accessory pathways. PATIENTS AND METHODS: Feasibility of radiofrequency ablation using a simplified two-catheter technique without coronary sinus catheterization was prospectively studied in 95 consecutive patients with a single concealed left free-wall accessory pathway. A 6F quadripolar catheter was introduced into the right atrium/right ventricle and tachycardia was induced by electrical stimulation. The presence of a concealed left-sided accessory pathway was suggested electrocardiographically (negative P wave in I and/or aVL during orthodromic tachycardia) or by earlier atrial activation in the pulmonary artery compared to the right atrium. Mapping of the mitral annulus and ablation were performed during orthodromic tachycardia or ventricular pacing using a 7F steerable catheter. Radiofrequency energy was applied at sites with the shortest VA interval. The procedure was considered effective if tachycardia could not be induced and if VA dissociation or exclusive nodal VA conduction were observed. RESULTS: The procedure was initially successful in 93 out of 95 patients (98%). Mean number of applications were 3.2 +/- 2. Mean fluoroscopy time and total procedure duration were 14 +/- 9 and 108 +/- 33 minutes respectively. At a mean follow-up of 21 +/- 13 months, 2 patients required a second session because of tachycardia recurrence. CONCLUSIONS: Radiofrequency catheter ablation of concealed left-sided accessory pathways can be safely, effectively and rapidly performed using a two-catheter technique without coronary sinus catheterization.

Adult↗
PubMed1997

Radiofrequency ablation of concealed left free-wall accessory pathways without coronary sinus catheterization: results in 100 consecutive patients.

INTRODUCTION: Feasibility of radiofrequency (RF) ablation using a two-catheter technique without coronary sinus catheterization was studied in 100 consecutive patients with a single concealed left free-wall accessory pathway. METHODS AND RESULTS: Tachycardia was induced by electrical stimulation in the right atrium/right ventricle, and the presence of a concealed left free-wall accessory pathway was suggested electrocardiographically (negative P wave in leads I and/or aVL during orthodromic tachycardia) or by earlier atrial activation in the pulmonary artery compared to the high right atrium. Mapping of the mitral annulus was performed during right ventricular pacing or orthodromic tachycardia, and RF energy was applied at the site with the earliest retrograde atrial activation. Ablation was considered effective if tachycardia could not be induced, and if VA dissociation or exclusive retrograde nodal conduction was observed. Ablation was initially successful in 98 of 100 patients. Mean number of radiofrequency pulses were 3.2 +/- 2. Mean fluoroscopy time and total procedure time was 14 +/- 9 and 107 +/- 32 minutes, respectively. There were no complications related to the procedure. At a mean follow-up of 22 +/- 13 months, two patients experienced tachycardia recurrence and required a second procedure, which was successful. CONCLUSIONS: Our results suggest that RF catheter ablation of concealed left free-wall accessory pathways can be safely, effectively, and rapidly performed using a simplified two-catheter technique with no need for coronary sinus catheterization.

Adult↗
PubMed1996

[Heart block caused by hyperkalemia as a complication of ureteroileostomy].

Report case of a patient who, after an ureteroileostomy, developed complete atrioventricular block secondary to severe hyperkaliemia, a condition for which no references have been found in the literature. Special mention is made of the mechanisms which trigger the electrolytic changes in these by-pass techniques.

Aged↗
PubMed1996

[One thousand consecutive radiofrequency ablation procedures. Indications, results, and complications].

INTRODUCTION: Radiofrequency ablation has become the treatment of choice in the majority of patients suffering from cardiac arrhythmias. In this study we present our experience in a large group of patients treated using this procedure. METHODS: Between January 1992 and February 1996, we performed 1000 consecutive ablation procedures in 938 patients with different cardiac arrhythmias. The indication for ablation were: tachycardias due to the presence of an accessory pathway (n = 487), atrio-ventricular nodal reentrant tachycardia (n = 284), atrio-ventricular nodal ablation (n = 104), atrial tachycardia (n = 42), atrial flutter (n = 41) and ventricular tachycardia (n = 42). RESULTS: Radiofrequency ablation was initially effective in 908 out of the 938 patients (97%). Effectiveness ranged from 100% in atrio-ventricular nodal ablation to 83% in atrial tachycardia. During follow-up, a total of 45 recurrences of the arrhythmia were documented (5%) ranging from 2% in atrial tachycardia to 28% in atrial flutter. In 40 out of the 45 patients a second procedure was performed, being effective in 34 of them. Finally, radiofrequency ablation was effective in 896 out of the 938 patients (96%). A total of 13 significative complications were observed (1.3%). Of them, 10 occurred during the 250 initial procedures (4%) and 3 in the remaining 750 procedures (0.4%). CONCLUSIONS: In centers performing a large number of procedures, radiofrequency ablation is a safe and effective method for the treatment of the majority of cardiac arrhythmias.

Adolescent↗
PubMed1995

Radiofrequency catheter ablation of atriofascicular accessory pathways guided by discrete electrical potentials recorded at the tricuspid annulus.

BACKGROUND: The purpose of this study was to test the feasibility of using the recording of discrete electrical potentials to guide radiofrequency catheter ablation of atriofascicular accessory pathways with Mahaim-like properties. METHODS AND RESULTS: Four patients (3 females, 1 male) who fulfilled criteria for having atriofascicular accessory pathways with Mahaim-like properties and preexcited reciprocating tachycardia underwent radiofrequency catheter ablation. The mean age was 35 years (range 27-47). Symptoms were present for a mean of 10.5 years (range 6-18). Recording of discrete electrical potentials of the atriofascicular pathway was attempted by mapping the tricuspid annulus in sinus rhythm, during atrial pacing, and during reciprocating tachycardia. During atrial pacing, a mean of seven radiofrequency pulses (range 1-14), delivered to the tricuspid annulus at the area where electrical potentials were recorded, eliminated conduction through the atriofascicular accessory pathway in all patients. No complications occurred. Tachycardia did not reoccur during a mean follow-up of 5 months (range 3-9). CONCLUSIONS: Recording of discrete electrical potentials at the tricuspid annulus identifies an optimal ablation site where radiofrequency current can safely eliminate conduction through atriofascicular accessory pathways with Mahaim-like properties.

Adult↗
PubMed1994

A five year review of youth suicide in Manitoba.

Suicide is the second leading cause of death in adolescents. The suicide rate in the 15 to 24 year old age group has increased at a faster rate than in any other age group. This study is a descriptive and retrospective investigation of 204 files from the Chief Medical Examiner's office of all youths aged 24 years and less in the province of Manitoba who committed suicide between 1984 and 1988. The study found a high male to female ratio, a large number of younger adolescents and a suicide rate in the Native population which was ten times that of non-Natives. The method of suicide varied by gender and race. Males more often used hanging and guns; females were more likely to overdose. Natives tended to hang themselves more than non-Natives, while non-Natives more often used guns. The highest percentage of Native suicides occurred in urban areas. Depression and substance abuse were identified as risk factors. A number of recommendations regarding information gathering post-suicide, as well as prevention and intervention programs are proposed.

Adolescent↗
PubMed1994

The right to refuse treatment: recent Canadian developments.

In this article, we examine one of the most contentious and divisive issues in mental health law: the right of the involuntary patient to refuse treatment. The recognition of this right can be traced to American case law starting in mid-1970s. The passing of the Canadian Charter of Rights and Freedoms in 1982 precipitated somewhat similar developments in Canada. Many provincial Mental Health Acts have been changed to reflect this newly acknowledged right. In addition, there have been two recent court decisions in Canada, Thwaites v. Health Sciences Center and Fleming v. Reid, which reflect the impact of the Canadian Charter on this issue. The right to refuse treatment has implications for the field of psychiatry.

Canada↗
PubMed1994

[Radiofrequency ablation of the slow nodal pathway in cases of paroxysmal nodal reentry tachycardia].

INTRODUCTION: We describe our experience in the treatment of supraventricular tachycardia due to atrioventricular nodal reentry by radiofrequency catheter ablation of the slow pathway. PATIENTS AND METHODS: Thirty-four patients (mean age 52 +/- 13 years) with recurrent drug refractory atrioventricular nodal reentrant tachycardia underwent radiofrequency catheter ablation of slow-pathway as the first procedure. Maximal energy used was 28 +/- 8 W, mean time was 4.4 +/- 2.8 min, and a mean number of 13 +/- 9 discharges per patient. RESULTS: Of the 34 patients 14 were successfully treated (no slow-pathway conduction, no AV nodal reentrant echo complexes, no inducible tachycardia), 11 were considered as partially successful (no inducible tachycardia, with slow-pathway conduction or echoes) and 9 patients were unsuccessfully treated (all of them underwent fast-pathway ablation with a successful outcome). Eight recurrences were observed during a mean follow-up period of 7 +/- 4 months: One in a patient with previously successful ablation (remained asymptomatic while taking beta-blockers), 6 in patients with first procedure partially successful (all of them underwent effective second slow-pathway ablation) and 1 in a patient with an unsuccessful procedure that underwent fast pathway ablation. A repeated procedure was successful in ablating the slow pathway. None of our patients developed complete atrio-ventricular block. One patient developed cardiac tamponade that needed surgical drainage. At last follow-up all patients are free from tachycardias. CONCLUSION: Slow pathway ablation is an effective method of treatment in patients with atrio-ventricular nodal reentrant tachycardia. Long term success is related to complete abolition of slow pathway conduction.

Adolescent↗
PubMed1993

[Early diabetic nephropathy in a patient with agenesis of one kidney].

A 24 year old male diagnosed of type II diabetes mellitus of 2 years of known clinical evolution discovered by an episode of hyperglycemic decompensation without ketoacidosis is presented. In the study of possible visceral involvement of the disease agenesis of the left kidney with compensating hypertrophy of the right kidney, increase of glomerular filtrate and proteinuria of 1.8 g/24 hours were observed. Renal histologic study demonstrated the existence of diffuse intercapillar glomerulosclerosis compatible with diabetic glomerulopathy. From these data and review of the literature the possibility of the greater risk of individuals with a single kidney to present nephropathy in the case of coexistence of associated diabetes mellitus.

Adult↗
PubMed1993

Feasibility of early discharge after acute Q wave myocardial infarction in patients not receiving thrombolytic treatment.

OBJECTIVES: The purpose of this study was to analyze the feasibility of early discharge (4 days) after acute myocardial infarction in patients not receiving thrombolytic therapy by first identifying predictors of short-term prognosis and then testing the derived risk profile in an independent cohort of patients. BACKGROUND: Previous studies have shown that early discharge after acute myocardial infarction is possible. However, physicians are reluctant to shorten the standard 7- to 10-day hospital stay, presumably because of difficulty in selecting low risk patients. METHODS: From January 1985 to November 1986, 358 patients with acute myocardial infarction who did not receive thrombolytic therapy were screened. Those with a Q-wave infarction showing no complications on day 4 were considered candidates for early discharge and were transferred to the ward for a mean of 12 days. During this period, we looked for any event (cardiac or noncardiac) that would have prompted readmission if the patient had been previously discharged. Univariate and multiple regression analysis were performed to identify predictors of these events among 25 baseline variables. The derived risk profile was tested in an independent validation cohort. RESULTS: One hundred five (29.3%) of the 358 patients were free of symptoms on day 4, and 29 (27.6%) had at least one cardiac event, including four deaths and one reinfarction. Multivariate analysis selected diabetes, ejection fraction < 40% and age as independent predictors of events. Using the risk profile, 18 (13.2%) of the 136 validation cohort patients were categorized as low risk, and only 1 of them had a major event (progressive angina). Sensitivity for the risk profile was high (91%), but specificity was low (34%). CONCLUSIONS: The use of simple clinical variables may allow the safe reduction of hospital stay after infarction in selected patients. However because the proportion of candidates for early discharge is small (12.6%), it seems unlikely that the current policies on length of hospital stay will change in the near future.

Cohort Studies↗
PubMed1992

A profile of the noncompliant patient: a thirty-month review of outpatient psychiatry referrals.

Missed appointments to outpatient psychiatry programs have been identified as a major form of noncompliance in the literature. Over a two-and-a-half year period, 874 referrals to the outpatient psychiatry department of a large teaching hospital were examined for significant differences between compliant and noncompliant patients. Noncompliant patients comprised 17.8% of the total number of cases dispositions and were significantly more likely to be single, diagnosed personality disorder or substance abuse, and referred from the Emergency Department than complaint patients. Further analysis of emergency referrals, the single most significant predictor, indicated that patients from this referral source were more likely to be male, unmarried, unemployed or on welfare, and diagnosed personality disorder or substance abuse than referrals from general practice and internal sources. The results are discussed in light of previous research, and recommendations are made for increasing compliance to outpatient appointments.

Adult↗
PubMed1991

Who misses appointments? An empirical analysis.

Patient noncompliance is a major problem in clinical practice. In order to better understand this issue, 236 appointments at an outpatient psychiatry clinic of a large urban general hospital were examined. Five variables significantly discriminated patients who kept their appointments from patients who did not. Patients who were younger, had a history of missed appointments, were scheduled to see a resident physician, had a routine appointment and lived a distance from the hospital, were at greater risk of missing their appointment. This information helps to identify patients at high risk of nonattendance and allows clinicians to plan schedules and appointments more efficiently.

Adult↗
PubMed1991

Psychogenic voice disorders: literature review and case report.

This paper explores some of the similarities and differences between hysteria and hypochondriasis and suggests that voice disorders are a prototype of disorders which reflect the intricate interplay of emotional, cognitive and physiological functions. Speech production requires the involvement of various systems of the body, including the central nervous system, respiratory and vocal systems. Voice disorders can take many different forms and can be caused by a variety of factors. A review of the relevant literature is presented along with a clinical case record of a woman with hysterical dysarthria.

Dysarthria↗