Necesidad de estimulación ventricular rápida en la inducción de taquicardia por reentrada del nodo aurículo-ventricular: Caso clínico / Requirement of fast ventricular stimulation to induce atrio ventricular nodal tachycardia: Report of one case

We report a 59 year-old woman who had recurrent episodes of paroxystic supraventricular tachycardia despite pharmacologic therapy. A previous electrophysiological study (EPS) was done two years earlier without induction of any sustained arrhythmia. A new EPS was performed, during which atrial and ventricular programmed stimulation failed to induce tachycardia, and only by fast ventricular stimulation during intravenous isoproterenol infusion, a typical atrio ventricular nodal reentrant tachycardia (AVNRT) was induced. We successfully ablated the slow nodal pathway. After ablation the tachycardia was not inducible. We comment the occasional difficulties to induce AVNRT and the importance of a complete induction protocol to avoid false negative studies during the EPS.

Seguimiento en fase aguda de catpeteres electrodos de estimulación endocavitaria permanente: Comparación de tres modelos / Comparison of three brands of intracardiac pacemarker leads

Background: Electrode lead design and materials influence their performance, stability and manipulation characteristics. In our laboratory, we use straight intracardiac, active fixation, steroid eluting leads. These features are shared by three brands of pacemarker distributors. Aim: To compare the short term results of three brands of leads used in our laboratory in patients requiring the implant of a pacemarker of cardioverter. Material and methods: One hundred and four patients (mean age 70 years, 59 males) subjected to a pacemarker or cardioverter implant were studied and followed during the first three months post implant. In these patients, 49 Guidant Flextend® 4087 or 4088, 27 Saint Jude Tendril® 1488T and 10 Medtronic Capsurefix® 5076 leads were implanted in the right atrium and 60 Guidant Flextend® 4087 or 4088, 29 Saint Jude Tendril® 1488T and 19 Medtronic Capsurefix® 5076 leads were implanted in the right ventricle. Results: Implant parameters were adequate for all leads. A sub-acute rise in ventricular stimulation threshold was detected in one Flextrend® lead. Three atrial leads (two Flextend® and one Capsurefix®) and one Capsurefix® ventricular lead experienced an acute displacement. One patient with a Flextend® lead, had a cardiac tamponade caused by an atrial perforation. Conclusions: The three brands of leads tested can be successfully implanted with comparable parameters and without differences in the evolution of patients during the first three months.

Experiencia en el uso de un nuevo catéter electrodo de estimulación endocavitaria: Seguimiento a un año / Experience in the use of a new endocardial stimulation electrode

Background: Since February 2002, Flextend® electrode catheters are used at the Cardiovascular Unit of the Catholic University Clinical Hospital. These transvenous catheters have an IS-1 connector, silicone coating, active fixation and retractile helix with dexamethasone acetate. Aim: To report early and one year results using Flextend® catheters. Material and methods: Retrospective analysis of all patients that received an implant of a Flextend® catheter in the Unit. Results: Forty one Flextend® catheters were implanted in 24 patients, without acute displacement or clinical pericarditis. In 18 electrode catheters located in the right atrium the mean values for p wave, stimulation threshold and impedance at the moment of placement, were 2.9±1.4 mV, 0.8±0.4 V and 522±86 Ohms, respectively. The figures 24 hours after placement were 3.6±2.1 mV, 0.8±0.3 V and 612±69 Ohms, respectively. In 23 electrode catheters in the right ventricle, mean values at the moment of placement for R wave, stimulation threshold and impedance were 11.3±3.6 mV, 0.8±0.2 V and 756±108 Ohms, respectively. The figures 24 hours after placement were 3.6±2.1 mV, 0.8±0.3 V and 612±69 Ohms, respectively. In one patient, the stimulation threshold increased two months after placement and required a new intervention. Conclusions: Flextend® catheters ca be placed successfully with a low rate of complications and stable function parameters on follow up.

Implante de marcapaso definitivo en pacientes con vena cava superior izquierda persistente y ausencia de vena cava superior derecha: Caso clínico / Permanent pacemaker implantation in patients with persistent left superior vena cava and absent right superior vena cava: Report of three cases

Persistent left superior vena cava and absent right superior vena cava is an uncommon anatomical association. This is a challenging situation for permanent pacemaker implantation. We report three patients with this anomaly and a permanent pacemaker successfully implanted through the left superior vena cava and coronary sinus, without acute or chronic complications.

Estimulación ventricular derecha multisitio en insuficiencia cardíaca refractaria a tratamiento con resincronización biventricular / Multisite right ventricular stimulation for cardiac failure refractory to biventricular resynchronization therapy. Case report

The prevalence of congestive heart failure has increased in the world. Despite advances in pharmacological treatment, some patients have progression of the disease and deterioration of their functional class. In this group of patients cardiac resynchronization therapy has been accepted as a treatment option. However, some patients are non-responders to cardiac resynchronization, and others who respond favorably, will experience reappearance of their symptoms. For these patients, multisite stimulation with the implant of a second electrode in the right ventricle has been published as a new option. We report a 76 year-old woman with a dilated cardiomyopathy, who was treated with resynchronization therapy with good clinical response during two years, but symptoms of congestive heart failure reappeared and her functional class deteriorated to NYHA class IV. She was successfully treated with right ventricular multisite stimulation, with a reduction of symptoms that has lasted during the two months of follow up after the procedure.

Experiencia de plan piloto para pacientes del FONASA portadores de arritmias atendidos en el Hospital Clínico de la Pontificia Universidad Católica de Chile / Treatment of beneficiaries of the Chilean public health system with arrhythmias in a University Clinical Hospital

Background: The costs of medical care increase along with technological advances. Therefore, highly complex and expensive procedures should be performed in a limited number of institutions. Aim: To report the initial experience on electrophysiological studies performed to beneficiaries of a public health insurance system in Chile (FONASA). Material and methods: An agreement was reached between the Electrophysiology Unit of the Clinical Hospital of the Catholic University and FONASA, to perform electrophysiological studies at a minimal cost, that only considered disposable materials and hospital stay. Thirty patients with supraventricular arrhythmias or ventricular arrhythmias without an associated cardiopathy, were attended using this agreement at the unit. Results: In all treated patients, arrhythmias disappeared. Costs remained within the assigned budget, excepting occasional complementary tests. Conclusions: This pioneering experience demonstrated that it is possible that public health insurance systems can buy complex and expensive procedures to private hospitals.

Fulguración con radiofrecuencia de taquicardia ventricular después de corrección quirúrgica de Tetralogía de Fallot: Caso Clínico / Radiofrequency ablation of ventricular tachycardia in a patient after surgery for Tetralogy of Fallot: Case report

Ventricular tachycardia is one of the most feared complications after surgical repair of Tetralogy of Fallot and it is associated with sudden death. We report a 26 years old female with a history of surgical repair of Tetralogy of Fallot at age of 4 year-old, who developed sustained ventricular tachycardia despite antiarrhythmic drugs. She was successfully treated with radiofrequency catheter ablation. Radiofrequency catheter ablation is a valid treatment for these patients.

Dolor torácico y alteración del segmento ST en pacientes con vías accesorias aurículo-ventriculares: Report of three cases / Chest pain and ST segment abnormalities in patients with accessory atrioventricular pathways

We report three patients with pre-excitation syndrome that resembled an acute coronary syndrome. A 65 years old woman, consulting in the emergency room for palpitations and retrosternal pain. EKG showed regular tachycardia and ST depression that reverted spontaneously after an episode of vomiting. A subsequent EKG demonstrated a pre-excitation syndrome and the accessory pathway was fulgurated. A 18 years old male presenting with tachycardia and chest pain elicited during exercise. An EKG showed a pre-excitation syndrome and ST segment elevation in V2 and V3. A coronary angiogram was normal. The accessory pathway successfully fulgurated. A 63 years old woman that presented tachycardia while exercising. She was subjected to an electrical cardioversion. An electrophysiological study showed an accessory pathway that was successfully fulgurated.

Flutter auricular: Resultados inmediatos y alejados de la fulguración con radiofrecuencia del istmo cavo-tricuspídeo / Results of radiofrequency ablation of the inferior vena cava-tricuspid valve isthmus for atrial flutter

Background: Radiofrequency ablation of the inferior vena cavatricuspid valve isthmus relieves atrial flutter in 95percent of cases. Aim: To evaluate the long term results of radiofrequency ablation of the inferior vena cavatricuspid valve isthmus in atrial flutter. Material and methods: Retrospective review of 86 patients with common atrial flutter, treated with radiofrequency ablation of the isthmus, while in sinus rhythm or flutter. Patients were contacted by telephone for a new clinical and electrocardiographic assessment, three to 40 months after the procedure. Results: Of all the patients treated, five died and five were lost from follow up, thus 76 patients (mean age 56 years, 58 males) were contacted for reassessment. At the moment of the procedure, 51percent had an underlying cardiac disease and 25percent had high blood pressure. All referred palpitations, 25percent had dyspnea, 84percent were receiving antiarrhythmic drugs and 33percent were on oral anticoagulants. Flutter was paroxystic in 83percent and chronic in 17percent. Fulguration was successful in all patients; one patient presented a high grade atrioventricular block as a complication of the procedure. At reassessment, 82percent of patients were in sinus rhythm, 16percent had atrial fibrillation and 2percent, an atypical flutter. Conclusions: Radiofrequency fulguration is a safe and effective treatment of atrial flutter.

Taquicardia recíproca de la unión auriculoventricular: características electrofisiológicas en un paciente con la variedad paroxística. Caso clínico / Paroxysmal tachycardia in a patient with a permanent form of junctional reciprocating tachycardia

Junctional reciprocating tachycardia is an atrioventricular reentrant tachycardia whose anterograde conduction occurs via the His Purkinje and the retrograde conduction via an accessory pathway with slow conduction. The most common form is incessant tachycardia but a paroxysmal form also exists. We report a 35 years old female with recurrent paroxysmal tachycardia, that underwent electrophysiological evaluation. A left posterolateral accessory pathway was documented. Reciprocating paroxysmal tachycardia was induced by electrical stimulation and a successful pathway ablation was performed (Rev MÚd Chile 2004; 132: 608-13).

Características clínicas y electrofisiológicas de pacientes fulgurados con radiofrecuencia por taquicardia por reentrada nodal típica / Clinical and electrophysiological characteristics of patients with atrioventricular nodal reentry tachycardia who underwent slow pathway ablation

AV nodal reentry tachycardia (AVNRT) is the most common cause of paroxysmal supraventricular tachycardia. Radiofrequency ablation is today the treatment of choice. Aim: To report our experience in patients who underwent slow pathway ablation. Patients and methods: Fifty six consecutive patients (68% female, mean age 43 years old) that underwent slow pathway ablation are reported. Results: Sixty four percent of patients had failed drug therapy. During electrophysiological study, AVNRT was induced in 55 patients. Isoproterenol was required for induction in 36%. Programmed atrial stimulation revealed dual AV nodal pathway in only 64% of the patients; 29% had AVNRT with single nodal curve and 7% only prolongation of AH interval. The slow pathway was ablated in 55 patients. One patient refused ablation because of risk of AV block. All patients had immediate success post ablation. Sixty four percent of patients persisted with partial evidence of dual curve manifested by sudden AH prolongation and single echoes. Conclusions: Isoproterenol is essential for ruling out AVNRT, since 29% of the patients had baseline single nodal curve and in only 64% was tachycardia induced without isoproterenol. Persistence of residual dual physiology does not rule out the success of ablation (Rev Méd Chile 2003; 131: 1237-42).

Flutter auricular crónico: una manifestación infrecuente de enfermedad del nódulo sinusal: caso clínico / Chronic atrial flutter as an infrequent manifestation of sick sinus syndrome: report of 1 case

We report a 41 years old female, previously operated of an atrial septal defect, presenting with a persisting atrial flutter. Sinus node dysfunction became evident during an electrophysiological study at the moment of interrupting the flutter with electrical stimulation. The patient was treated with his bundle ablation and implantation of a definitive pacemaker. After one year of follow up, she is devoid of symptoms

Taquicardia paroxística supraventrictular con disociación ventrículo auricular: a propósito de un caso / 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 relocities and refractory periods in the atrioventricular mode. These are the slow and fast nodal pathways. That ventricular tissue does not form part of the circuit of this arrbythmia 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 electrophystological study be presented an atrial and ventricular dissociation during the tachycardia. These findings allow a better undestanding of the electrophysiological substrae of this arrhytmia

Taquicardia ventricular idiopática originada en el ventrículo izquierdo / Idiopathic ventricular tachicardia originated at left ventricle

Patients and methods: We report six patients (five male), aged 35 years old as a mean, with idiopathic left ventricular tachycardia that were subject to conventional electrophysiological studies with atrial and ventricular simulation programs and radiofrequency fulguration, between December 1993 and May 1996. Results: The mean lapse of disease was 24 months and five patients received antiarrytmic 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

Fulguración de haz izquierdo en paciente con transposición de grandes vasos / Left accessory bundle ablation in a patient with transposition of great vessels

En este artículo presentamos el caso clínico de un paciente con cirugia de Senning por transposición de los grandes vasos, quien fue sometido a fulguración con radiofrecuencia de un haz paraespecífico izquierdo. Se ha documentado la asociación entre esta condición clínica y la presencia de arritmias auriculares, pero no encontramos datos publicados de tratamiento con radiofrecuencia en un paciente con cirugia de Senning y taquicardia paroxística supraventricular por un haz paraespecífico.

Fulguración con radiofrecuencia de la vía nodal lenta: experiencia en 30 casos consecutivos / Radiofrequency fulguration of the slow nodal pathway: experience in 30 consecutives cases

Atrioventricular nodal reentry tachycardia (AVNRT) is one of the most 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 here 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 37ñ3.7 years. All patients had symptomatic tachycardia and six had history of syncope. Electrophysiological studies revealed AVNRT in all patients, in addition, 2 patients had a left accesory pathway. Slow pathway ablation was performed with Mansfield 7 F catheter, guided by both fluoroscopic positioning and endocardial signals. A mean of 13 burst were applied. In the 30 patients conduction though the slow pathway was interrupted and thus tachycardia was no longer inductible. 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 15.7ñ2.5 months and are asymptomatic in the absence of antiarrhythmic therapy

Fulguración por radiofrecuencia de haces paraespecíficos / Fulguration by radiofrecuency of paraspecific bundles

Between august 1991 and august 1993, 75 patients (42 male) with Wolff Parkinson White syndrome (43 concealed) were subjected to radiofrequency ablation of accesory pathway at our institution. 55 had left, 8 postero septal, 2 anteroseptal and 10 right accesory 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 accesory pathways and for some with posteroseptal pathways were ablated using a right heart approach placing the ablation catheter in the tricuspid annulus. Ablation was successful in 61 patients (81 per cent ). 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 accesory pathways is a curative procedure for a great majority of patients with Wolf Parkinson White syndrome

Ablación por radiofrecuencia de haces auriculoventriculares anómalos en niños con taquicardia paroxística supraventricular / Radiofrequency ablation of abnormal atrioventricular bundle in children with paroxysmal supraventricular tachycardia

En 21 pacientes (edad promedio 9,7, márgenes 4 a 16 años) con taquicardias paroxísticas supraventriculares por haces paraespecíficos, se realizaron estudios eslectrofisiológicos y ablación de los haces por radiofrecuencia. Dos pacientes tenían malformaciones congénitas del corazón. La ablación se consiguió en 12/15 haces anómalos izquierdos (80 por ciento) y en 4/6 derechos (67 por ciento), en 10/12 pacientes con preexitación (83//) y 6/9 haces ocultos (67 por ciento) (diferencias no significativas). El buen éxito se obtuvo en 76 por ciento (16/21) del total de pacientes, pero éste aumentó a 84 por ciento (p=0,048 Fisher) después de eliminar los pacientes con malformaciones congénitas. Las complicaciones observadas incluyeron obstrución arterial con síndrome de compartimiento y perforación con taponamiento (un caso de cada una). La ablación por radiofrecuencia es un tratamiento adecuado y definitivo en niños con taquicardia paroxística supraventricular,independientemente de la localización de la vía anómala y la presencia de preexitación, pero puede fracasar en casos de malformaciones cardíacas. Las complicaciones de importancia son poco frecuentes, pero pueden llegar a ser graves, lo que exige una rigurosa selección de los pacientes a estudiar