Terapia de resincronización cardiaca en paciente con vena cava superior izquierda persistente: Caso clínico / Placement of a biventricular resynchronization device in a patient with a persistent left superior vena cava: Report of one case

Persistent left superior vena cava is the most common venous congenital malformation and is usually asymptomatic. Its presence could increase the difficulty for transvenous lead implantation. We report a 71-year-old woman with an idiopathic dilated cardiomyopathy, atrial fibrillation and heart failure that required biventri-cular resynchronization therapy. During the placement of the device a persistent left superior vena cava was detected. The device was placed without problems and the patient had a satisfactory postoperative evolution.

Síndrome de Twiddler: una causa infrecuente de disfunción de marcapaso definitivo. Caso clínico / Twiddler syndrome: Report of one case

We report a 26year old patient who had a single chamber pacemaker implantation one year before. During a routine pre-operative evaluation, pacemaker dysfunction was demonstrated due to sensing and pacing failure, associated to left pectoral muscle rhythmic contraction. Chest X-ray confirmed Twiddler syndrome, in which twisting or rotation of the device inside the pocket results in lead dislodgement and device malfunction.

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.

Pérdida de resincronización biventricular: Causa inhabitual. Caso clínico / Loss of biventricular resynchronization due to an uncommon cause: Report of one case

Cardiac resynchronization therapy is a non-pharmacological treatment for patients with dilated cardiomyophaty and congestive heart failure. The success of this therapy depends of permanent biventricular stimulation. We report an 84 year-old man, with intermittent loss of biventricular pacemaker stimulation despite having adequate sensing and stimulation thresholds in the right atrium and both ventricles. The problem was solved after correcting some programming parameters.

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.

Mixoma auricular izquierdo recurrente en niño de 2 años / Recurrent left atrial myxoma. Report of a case in a 2 year-old boy

Primary cardiac tumors are uncommon in pediatric patients. We report a two year-old boy, who presented a recurrent left atrial myxoma. He was referred for cardiologic evaluation because of cardiomegaly on a chest X-ray. An echocardiography showed a big left atrial tumor attached to the atrial septum. The tumor was uneventfully removed and the pathological examination confirmed a myxoma. He remained asymptomatic and during a follow up echocardiography two years later, a recurrent tumor was noted. He was successfully operated again, remaining free of a new recurrence after 3 years of follow up.

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.

Reemplazo valvular mitral y aórtico en niños: resultados durante la última década con prótesis de última generación / Mitral and aortic valve replacement in children: last decade results with latest generation prothesis

Antecedentes: El reemplazo valvular mitral (RVM) y aórtico (RVA) es poco frecuente en pacientes pediátricos y las series publicadas reportan elevada morbi-mortalidad. Objetivo: Evaluar los resultados a mediano plazo en niños sometidos a RVM y RVA durante los últimos diez años, con el fin de determinar morbimortalidad y calidad de vida. Método: Análisis retrospectivo de 26 niños consecutivos (mediana de edad 5,6 años) sometidos a RVM y RVA, entre marzo 1992 y junio 2003. Diecisiete presentaban patología mitral y once aórtica. Resultados: Se realizaron 26 operaciones implantando 28 prótesis (26 mecánicas y 2 biológicas). Tres pacientes (12 por ciento) fallecieron durante el primer mes. La mediana de seguimiento fue de 6,2 años. Tres pacientes con RVM fallecieron alejadamente por causa no atribuible al reemplazo valvular con una sobrevida actuarial de 87 por ciento. Tres pacientes requirieron reoperación. Todos realizan actividades adecuadas a su edad, restringiéndose los deportes de contacto. Conclusión: Los resultados a mediano plazo del reemplazo valvular en niños con valvulopatía grave son satisfactorios.

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.

Cirugía paliativa mediante operación de Norwood en distintas formas de corazón univentricular: resultados quirúrgicos inmediatos / Immediate results of palliative surgery for different forms of univentricular heart using the Norwood procedure

Background: Norwood procedure is used as the first stage in the palliative treatment of the hypoplastic heart syndrome and can be used, with some technical modifications, in other forms of univentricular heart with aortic stenosis or hypoplasia. These patients have a high mortality (50 percent), derived from the procedure itself and from their abnormal physiological status. Aim: To report our experience with the Norwood procedure. Patients and methods: Retrospective analysis of all patients subjected to the Norwood procedure between February 2000 and June 2003. Results: Thirteen patients (9 females, age range 5-60 days and median weight of 3.3 kg) were operated. Eight had hypoplastic heart syndrome and five had a single ventricle with aortic arch hypoplasia. The diagnosis was done in utero in eight patients. All technical variations, according to the disposition and anatomy of the great vessels, are described. Cardiac arrest with profound hypothermia was used in all and regional cerebral perfusion was used in nine. Three patients died in the perioperative period and three died in the follow up (two, four and 10 months after the procedure). Gleen and Fontan procedures were completed in five and one patients, respectively. Conclusions: Our results with the Norwood procedure are similar to other series. There is an important mortality in the immediate operative period and prior to the Glenn procedure (Rev MÚd Chile 2004; 132: 556-63).

Operación de Fontan: resultados inmediatos y a mediano plazo con anastomosis cavopulmonar total / Fontan procedure: early and mid-term results wiht total cavopulmonary anastomosis

Background: During the last five years, 65 patients with univentricular heart have been treated surgically in our institution, according to a protocol of staged operations that have been previously reported. Aim: To evaluate the early and mid-term outcome of those patients that have completed their staging protocol by means of a Fontan procedure. Patients and Methods: Between April 1996 and June 2001, 23 patients (age 16 to 223 months) underwent a Fontan procedure, 15 with an intracardiac lateral tunnel technique and 8 with an extracardiac conduit. A retrospective review of their clinical, surgical, echocardiographic, angiographic and hemodynamic data was performed, trying to identify risk factors for both mortality and functional capacity (FC). Follow up was complete in all survivors. Results: Three patients died early after surgery (13.04 percent). Excessive pulmonary blood flow was a risk factor for early death (p= 0.03). One patient died at 14 months. Follow up was 29.9 months (1-63). For those who survived the operation, five years survival was 93.3 percent. The majority of patients are in FC I or II, with no related risk factors. Conclusions: Our current results are comparable with those of larger series. Patients reach good FC and mid-term survival, irrespective of type of single ventricle or the surgical strategy

Cateterización del bulbo yugular en niños con traumatismo encefálico grave / Yugular bulb blood oxygen saturation in children with severe head trauma

Objetivo: destacar la utilidad de la medición de la saturación de oxígeno en la sangre venosa del bulbo yugular (SatBYO2) en la vigilancia y manejo de la hipoxia o isquemia cerebral global en pacientes con traumatismo encéfalocraneano grave y sus correlaciones con las presiones arterial media, intracraneana y de perfusión cerebral. Pacientes y métodos: once niños (promedio de edades 98 meses, nueve varones), con traumatismo craneoencefálico grave (calificación de Glasgow igual o menor a 8), causado por impacto con vehículos en la vía pública, fueron admitidos a una unidad de cuidados intensivos pediátricos de un hospital suburbano de Santiago durante un período de 12 meses. En todos se introdujo un catéter en el bulbo yugular y se hicieron mediciones de SatBYO2. Resultados: la SatBYO2 era anormalmente baja en cuatro pacientes, en todos había acentuada hiperventilación y en dos hipertensión intracraneana, pero se normalizó mediante ajustes en los controles de los ventiladores mecánicos y el manejo efectivo de la hipertensión intracraneana. No se registraron complicaciones debidas al procedimiento. Todos los pacientes sobrevivieron. Conclusiones: el método es aplicable y seguro en pacientes de unidades pediátricas de cuidados intensivos. La medición de la SatBYO2 es útil como complemento en la evaluación de la oxigenación global cerebral en pacientes con traumatismo encéfalocraneano grave