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Biomedical subjects

I Vergara

Publications and source records attributed to I Vergara.

At least 19 recordsLinked to original sources
PubMed1998

Ventricular tachycardia and fibrillation in normal hearts.

Although ventricular tachyarrhythmias usually occur in the setting of definable heart disease, up to 15% of ventricular tachycardias and 10% of ventricular fibrillation occur in patients without heart disease. Of the various clinical entities comprising these idiopathic ventricular tachyarrhythmias, a few well-defined clinical syndromes have been described, such as idiopathic right ventricular outflow tract tachycardia, idiopathic left posterior fascicular ventricular tachycardia, and the right bundle branch block and ST segment elevation syndrome of idiopathic ventricular fibrillation. Many advances have been made in the past few years in our understanding and treatment of idiopathic ventricular tachyarrhythmias, and these advances are the subject of this review.

Catheter Ablation↗
PubMed1998

[Late effects of radiofrequency fulguration: report of five cases].

Radiofrequency fulguration is the definitive treatment of several supraventricular and ventricular arrhythmias. During radiofrequency application, the conduction in a specific zone is interrupted as a consequence of cellular necrosis and edema. The disappearance of edema, minutes or hours after the procedure, allows the reappearance of conduction and arrhythmias. On the other hand, the definitive lesion is larger than the one caused acutely, due to the progression of the scar. We report five patients, in whom there was an apparent failure of the fulguration, since at the end of the procedure there was conduction in the fulgurated zone, the tachycardia was inducible or pre excitation and arrhythmias reappeared during the follow up. All five were subjected to a new electrophysiological study and in all, fulguration had been effective. We conclude that these late effects of fulguration are due to the slow progression of fibrosis, that continues days or weeks after the procedure.

Adolescent↗
PubMed1998

[Radiofrequency ablation of right accessory pathways].

BACKGROUND: Accessory pathways are muscular connections between auricles and ventricles, present in different points of mitral and tricuspid annuluses. These pathways participate in 50% of paroxysmal supraventricular tachycardias and the definitive cure of the arrhythmia is their ablation. AIM: To report our experience in patients with right accessory pathways. PATIENTS AND METHODS: Fifty consecutive patients treated between 1990 and 1996 are reported. Eight had a history of syncope, two had a diagnosis of Ebstein disease and 36 had a pre-excitation in the surface electrocardiogram. RESULTS: Fifty four accessory pathways were identified, since four patients had two pathways. Twenty four pathways were posteroseptal, 15 were lateral, 9 were medioseptal and 6 were anteroseptal. One patient had also a nodal reentry tachycardia. Fulguration was attempted in 39 patients and it was finally successful in 32. Three patients required more than one session. There were six relapses and all were successfully ablated in a second session. A mean of 28 radiofrequency applications were done (range 1-76), mean laboratory time was 6 hours and mean radioscopy time was 70 min. Four patients had a transient atrioventricular conduction blockade. CONCLUSIONS: Radiofrequency ablation of accessory pathways has a high degree of success and a low rate of complications.

Adolescent↗
PubMed1998

[Ventricular reentry tachycardia within the bundle branches. Report of 3 cases].

Vientricular tachycardia due to reentry within the bundle branches occurs in the presence of left ventricular dilatation and conduction alterations in the His-Purkinje system. A macro-reentry is formed by the His bundle, left and right bundles and ventricular myocardium. The anatomical substrate of this arrhythmia is ventricular dilatation. However, it may appear in healthy hearts. Alterations of intraventricular conduction are reflected by a prolongation of PR interval and bundle branch block in the surface EKG and prolongation of HV interval in the endocavitary registry. During tachycardia, His activation precedes ventricular activation. We report three patients aged 55, 58 and 78 years old with a dilated cardiomyopathy and ventricular tachycardia due to reentry within the bundle branches. All had a left bundle branch block and a prolonged HV internal. The arrhythmia was induced during the study in two patients. All were subjected to radiofrequency fulguration of the right branch of the His bundle. After fulguration, two remained with a pattern of complete right bundle branch block and one with a complete intermittent AV block. All three are free of arrhythmic events.

Aged↗
PubMed1997

[Cardiovascular effects of AV interval shortening with electrical stimulation in dilated cardiomyopathy].

BACKGROUND: A temporal alteration between atrial and ventricular contraction, in which the last one would be abnormally retarded, could exist in patients with dilated cardiomyopathy. This alteration could have adverse hemodynamic effects. AIM: To study the hemodynamic modifications caused by an artificial shortening of AV interval in patients with dilated cardiomyopathy. PATIENTS AND METHODS: Nine patients with dilated cardiomyopathy were studied. Hemodynamic and tissular perfusion values, echocardiographic and radioisotopic ventricular function parameters were measured before and after six hours of AV interval shortening with electrical stimulation of the heart. RESULTS: After electrical stimulation, cardiac output increased from 3.38 +/- 0.8 to 3.87 +/- 0.79 l/min (p< 0.05). Pulmonary capillary pressure decreased from 23.8 +/- 8.9 to 19.8 +/- 9.2 mm Hg (p = NS). There were no significant changes in ventricular function parameters or in systemic and pulmonary pressures. CONCLUSIONS: Electrical shortening of AV interval in patients with dilated cardiomyopathy increases cardiac output but does not change ventricular function parameters.

Adult↗
PubMed1997

[Idiopathic tachycardia originated in left ventricle].

BACKGROUND: Idiopathic ventricular tachycardia occurs in patients with no structural heart disease and may originate in left of right ventricle. AIM: To report our experience with this condition. PATIENTS AND METHODS: We report six patients (five male), aged 35 years old as a mean, with idiopathic left ventricular tachycardia that were subjected to conventional electrophysiological studies with atrial and ventricular stimulation programs and radiofrequency fulguration, between December 1993 and May 1996. RESULTS: The mean lapse of disease was 24 months and five patients received antiarrhythmic medications previously. All tachycardias had a morphology with an image of right bundle branch block. Radiofrequency fulguration was done after obtaining a satisfactory pace mapping of at least 11 of the 12 superficial EKG derivations. The procedure was successful in five patients and two had a relapse. One of the relapsed patients was successfully fulgurated again. CONCLUSIONS: Radiofrequency fulguration for idiopathic ventricular tachycardias is a safe and effective therapeutic procedure.

Adolescent↗
PubMed1997

[Supraventricular paroxysmal tachycardia with ventriculo-atrial dissociation. Report of one case].

Nodal reentrant supraventricular paroxysmal tachycardia corresponds to a reentry circuit established between fibers with different conduction velocities and refractory periods in the atrioventricular node. These are the slow and fast nodal pathways. That ventricular tissue does not form part of the circuit of this arrhythmia is accepted nowadays, and the involvement of atrial tissue is discussed. We report a 57 years old male with a nodal reentrant tachycardia. In the electrophysiological study he presented an atrial and ventricular dissociation during the tachycardia. These findings allow a better understanding of the electrophysiological substrate of this arrhythmia.

Electrophysiology↗
PubMed1996

[Radiofrequency fulguration for supraventricular tachycardia in pediatrics].

Supraventricular tachycardias (SVT) are the most frequent cause of tachycardia in children. Its pharmacological treatment has adverse effects, is not curative, and is not always effective. During the last few years radiofrequency ablation (RF-A) has changed the treatment. The purpose of this study is to evaluate our experience in RF-A in children with SVT. Between 1990 and 1995, 92 patients (1 month to 17 years old) underwent electrophysiological study after the diagnosis of SVT. RF-A was attempted in 55 patients with accessory pathways (AP), slow-pathway of the atrioventricular node, or ectopic focus. The site of ablation was decided according to the electrical signals and the catheter position. The success of the RF-A was confirmed by the interruption of the tachycardia, the change in the sequence of activation of the intracardiac signals, the regression of the preexcitation, and the inability to reinduce tachycardia. RF-A was successful in 81% of the patients; 88% in those with a left AP, 56% in those with a right AP, and 100% in those with nodal reentry. Complications were seen in 7% of the patients: 3 with arterial obstruction, one with a minimal pneumothorax, and one with cardiac tamponade. During a follow up of 16.6 months there was no relapse nor late complications. We conclude that RF-A is a safe and effective procedure in pediatric patients with SVT.

Adolescent↗
PubMed1996

[Radiofrequency catheter ablation in patients with common atrial flutter].

BACKGROUND: Type 1 atrial flutter is produced by a reentry circuit located in the right atrium that can be interrupted applying radiofrequency in the inferior cava-tricuspid valve isthmus. AIM: To report our experience in the treatment of atrial flutter with radiofrequency ablation. PATIENTS AND METHODS: Nine patients (eight male) whose ages ranged from 6 to 72 years old were studied. Two patients had an operated congenital cardiopathy, two had high blood pressure, one was subjected previously to radiofrequency ablation due to a left paraspecific pathway, one developed a cardiac failure secondary to tachycardia and three did not have evidences of cardiopathy. RESULTS: In two patients, atrial flutter was not interrupted. In the other seven patients, radiofrequency ablation was successful. There were three relapses in the first month after the procedure, of these, two patients were successfully treated again. After a mean follow up of 4.5 months, these patients are asymptomatic and without antiarrhythmic drugs. Analysis of obtained signals, showed that radiofrequency that interrupted atrial flutter always occurred in zones of double potentials. CONCLUSIONS: Radiofrequency ablation is an effective treatment for atrial flutter and the zone of successful ablation is associated to the presence of double atrial potentials.

Adult↗
PubMed1995

[Arrhythmogenic right ventricular dysplasia. Options of treatment during a 12-year follow-up of a patient].

The replacement of muscle by fibrous and adipose tissue leads to arrhythmogenic right ventricular dysplasia. We report the clinical features and therapeutic options of a 50 years old male with the disease followed during 12 years. The latter included pharmacological therapy, surgical pseudoaneurysmal resection and radiofrequency fulguration of a second arrhythmogenic focus that appeared 10 after the surgical procedure. The patient remained asymptomatic after each therapy, until the disease progressed again. This follow up is one of the longest reported and documents the disease's clinical presentation, evolution and treatment.

Anti-Arrhythmia Agents↗
PubMed1995

[Diltiazem versus intravenous nitroglycerin in the treatment of unstable angina pectoris. A randomized study].

Prognosis of unstable angina pectoris is related to admission EKG changes and prompt symptom control. The aim of this study was to compare the clinical effects of intravenous diltiazem (DTZ) or nitroglycerin (NTG) in patients with unstable angina pectoris. We studied 43 patients admitted to the hospital with a history of rest angina within the last 48 hours, associated with EKG evidence of ischemia. All subjects received intravenous heparin and oral aspirin, 23 were randomly assigned to receive intravenous DTZ and 20 to receive intravenous NTG. Both groups had similar baseline features and the endpoints of treatment were recurrence of angina, myocardial infarction, death during hospitalization and secondary side effects. Treatment with DTZ, when compared to NTG, resulted in a significant reduction of recurrent angina (8.7 and 59% respectively; p < 0.005), number of angina episodes per patient (0.18 +/- 0.5 and 0.9 +/- 1.2 respectively; p < 0.05) and lower need for dose increment to control symptoms (3 and 9 patients respectively; p < 0.05). The most common side effects observed were cephalea with NTG (60% of patients) and asymptomatic sinus bradicardia with DTZ (28% of patients). In each group, one patient had a myocardial infarction and one patient died. It is concluded that intravenous DTZ reduces myocardial ischemia to a greater extent than NTG and can be safely used in patients with unstable angina pectoris.

Aged↗
PubMed1995

[Junctional reciprocating tachycardia: clinical and electrophysiological characteristics, and the role of fulguration in 5 cases].

The permanent form is a variety of junctional reciprocating tachycardia that is refractory to medical treatment. The anterograde arm of the circuit is formed by the His Purkinje bundle and the retrograde conduction is through a slow conduction Accessory Atrioventricular Pathway. We report five patients with this type of arrhythmia, subjected to electrophysiological assessment. Their mean age was 37 years, all suffered from palpitations and several medical treatments had failed. During tachycardia, electrocardiogram had a negative P wave in inferior leads and RP interval was bigger than PR interval. Accessory Pathway were located in the right postero-septal region in three patients, in the left postero-septal region in one and in the left lateral in one. Specific bundle fulguration was successfully attempted in four patients, in whom arrhythmias did not recur without medical treatment.

Adolescent↗
PubMed1995

[Fulguration with radiofrequency of the slow nodal pathway: experience in 30 consecutive cases].

Atrioventricular nodal reentry tachycardia (AVNRT) is one of the most frequent mechanisms of paroxysmal supraventricular tachycardia. In these patients tachycardia is maintained due to anterograde conduction through a slow pathway and retrograde conduction to the atrium via a fast pathway. We present herein our experience in ablation of the slow pathway. Since January 1993, 30 consecutive patients with AVNRT underwent attempted catheter ablation of the slow pathway. Mean age was 35 +/- 3.7 years. All patients had symptomatic tachycardia and six had history of syncope. Electrophysiologic studies revealed AVNRT in all patients, in addition, two patients had a left accessory pathway. Slow pathway ablation was performed with a Mansfield 7 F catheter, guided by both fluoroscopic positioning and endocardial signals. A mean of 13 bursts were applied. In the 30 patients conduction through the slow pathway was interrupted, and thus tachycardia was no longer inducible. Retrograde conduction post ablation was evaluated in 17 of the 30 patients, significant changes were observed in three of them. One patient developed second degree AV block and a permanent pacemaker was implanted. Another patient had recurrence of tachycardia three months post ablation. After a second attempt she is arrhythmia free. Patients have been followed for a mean of 15.7 +/- 2.5 months and are asymptomatic in the absence of antiarrhythmic therapy.

Adolescent↗
PubMed1994

Natural history of spinal cord infarction caused by nucleus pulposus embolism.

Nucleus pulposus embolism causing spinal cord infarction is exceptional. A 16-year-old girl was seen with sudden onset of interscapular pain and paraplegia from fatal ischemic transverse myelopathy due to arterial and venous occlusions by fibrocartilaginous embolism. In 32 cases of nucleus pulposus embolism, females predominated (69%) and age distribution was bimodal with peaks at 22 and 60 years (median, 38.5). Embolization was either arterial and venous (50%) or purely arterial (50%). Myelopathy predominated in cervical (69%) and lumbosacral (22%) segments. Schmorl's nodes, larger volume and vascularization of nucleus pulposus in the young, and spinal arteriovenous communications, trauma, and degenerative changes in older patients could be important pathogenetic factors. Diagnosis requires histopathologic confirmation. Nucleus pulposus embolism may be an underlying cause in cases diagnosed as transverse myelitis and ischemic infarction of spinal cord.

Adolescent↗
PubMed1994

[Hypertrophic cardiomyopathy with two episodes of recuperated sudden death. Report of the first implantable defibrillator cardioverter inserted in Chile].

We report a 29 years old male with a non obstructive hypertrophic cardiomyopathy that survived two episodes of cardiac arrest and with a familiar history of the disease and sudden death. He had an implant of an automatic implantable cardioverter defibrillator by a left anterior thoracotomy with intraoperative electrophysiology. The postoperative outcome was uneventful. After one year of follow up, the patient is in good functional capacity and the implanted device has not performed defibrillations.

Adult↗
PubMed1994

[Radiofrequency fulguration of accessory pathways].

Between August 1991 and August 1993, 75 patients (42 male) with Wolff Parkinson White syndrome (43 concealed) were subjected to radiofrequency ablation of accessory pathways at our institution. 55 had left, 8 postero septal, 2 anteroseptal and 10 right accessory pathways. A retrograde aortic technique with placement of the ablation catheter in close proximity to the mitral annulus was used for most of the patients with left accessory pathways and for some with posteroseptal pathways. The right, anteroseptal and some posteroseptal pathways were ablated using a right heart approach placing the ablation catheter in the tricuspid annulus. Ablation was successful in 61 patients (81%). One subject developed a fatal cardiac tamponade after a transeptal catheterization and was unrelated to the ablation per se. It is concluded that radiofrequency ablation of accessory pathways is a curative procedure for a great majority of patients with Wolf Parkinson White syndrome.

Adolescent↗
PubMed1993

Acute ischemic stroke from fibrocartilaginous embolism to the middle cerebral artery.

BACKGROUND AND PURPOSE: Fibrocartilaginous embolism from the nucleus pulposus has been reported as a rare cause of spinal cord ischemia. We were unable to find previous reports of embolism from this source to cerebral arteries. CASE DESCRIPTION: A previously healthy 17-year-old girl fell during a basketball game. Left hemiparesis and unresponsiveness developed followed by signs of right uncal herniation and death over a 3-day period. There was no evidence of neck, head, or spine trauma, and cardiac evaluation was normal. Neuropathological examination showed extensive ischemic infarction of the right middle cerebral artery territory, brain edema, and herniation. Complete embolic occlusion of the right middle cerebral artery by fibrocartilaginous material, consistent with nucleus pulposus, was documented. Small, terminal coronary artery branches also showed embolism by the same material and limited areas of myocardial infarction. CONCLUSIONS: Acute cerebral embolism after minor trauma in a young patient may be rarely due to fibrocartilaginous embolism from the nucleus pulposus. The pathogenesis of this problem remains poorly understood, but systemic embolism appeared to have occurred in this case.

Adolescent↗