Symptomatic, Inspiration-Induced Atrioventricular Block: Treated with Pacemaker Implant.

BACKGROUND: The respiratory sinus arrhythmia is the most common cardiac arrhythmia. It consists of phasic variations of sinus cycle length produced by an autonomic reflex, and is characterized by increased heart rate during inspiration and decline in expiration. This phenomenon is due to a reduction of the parasympathetic tone during inspiration, causing a rise in the heart rate, while during expiration the opposite phenomenon occurs. This arrhythmia is more frequent in young adults, although it can also be seen in any age group. METHODS AND RESULTS: We report the case of a 46-year-old female, who was transferred to our institution because of dizziness and loss of balance reported during deep inspiration, associated with sinus bradycardia and atrioventricular block.

Breast cancer and pacemakers.

AIMS: The combination of breast cancer and the need for a pacemaker is infrequent, and device implantation under these circumstances may be a technical challenge with several treatment options, most of them complex. METHODS AND RESULTS: Eight patients, all women, with an average age of 69.62 ± 11.4 years. We present a technique for patients with bilateral breast cancer who need a pacemaker or those who had already implanted a device and developed a homolateral breast cancer. All the pacemakers were implanted in a neck pocket, as a first implantation or if they were moved from a prepectoral pocket to the neck. Seven patients had a good outcome and one had an infection. CONCLUSION: We suggest a simple alternative to lead extraction or epicardial approach in patients with coexisting breast cancer and the need for a rhythm control device consisting in placing the device in a neck pocket and preserving the existing leads by tunnelling them either above or below the clavicle.

Lack of current implantable cardioverter defibrillator guidelines application for primary prevention of sudden cardiac death in Latin American patients with heart failure: a cross-sectional study.

AIMS: This cross-sectional study evaluated the application of accepted international implantable cardioverter defibrillator (ICD) guidelines for primary prevention of sudden cardiac death in patients with heart failure. METHODS AND RESULTS: The PLASMA (Probabilidad de Sufrir Muerte Arritmica) study was designed to characterize management of cardiac patients in Latin America. Twelve centres included 1958 consecutively admitted patients in cardiology units in 2008 and 2009. Discharged patients were evaluated for primary prevention, ICD indication and prescription by general cardiologists. Of 1711 discharged patients, 1525 (89%) had data available for evaluating indication status. Class I indications for ICD therapy were met for 153 (10%) patients based on collected data. Only 20 (13%, 95% confidence interval: 7.7-18.4%) patients with indication were prescribed an ICD. Patients prescribed an ICD were younger than patients who were not prescribed an ICD (62 vs. 68 years, P < 0.01). The reasons given by cardiologists for not prescribing an ICD for 133 patients with an indication were: indication criteria not met (75%), life expectancy <1 year (9.7%), rejection by the patient (5.2%), no medical coverage paying for the device (3.7%), psychiatric patient (2.2%), and other reasons (4.2%). CONCLUSIONS: In Latin America, international guidelines for primary prevention ICD implantation are not well followed. The main reason is that cardiologists believe that patients do not meet indication criteria, even though study data confirm that criteria are met. This poses a significant challenge and underlines the importance of continuous and improved medical education.

Role of nitric oxide in young patients with vasovagal syncope.

AIMS: Nitric oxide (NO) formed in the vascular endothelium produces, among other effects, a strong vasodilation. In order to evaluate the possible role of NO in hypotension induced by head-up tilt test (HUT), we measured plasma levels of its metabolites, nitrites and nitrates (NOx), during the test. METHODS AND RESULTS: Twelve patients with vasovagal syncope and positive HUT [HUT(+)] (mean age: 23+/-5 years) and 13 healthy volunteers with negative HUT (controls) (mean age: 24+/-5 years) were included. Venous blood samples were obtained during the baseline stage for biochemical measurements. Plasma values of NOx were obtained under baseline conditions (T0), at the end of the HUT (T1), and 15 min after the end of the HUT (T2). The baseline biochemical values as well as haemodynamic parameters were similar in HUT(+) patients and controls. NOx plasma values (in micromol/L) were as follows [HUT(+) vs. controls]: T0: 5.7+/-1.6 vs. 8.8+/-4.7 (P=0.05), T1: 6.1+/-3.2 vs. 8.5+/-3.6 (P=NS), and T2: 6.1+/-3 vs. 10.2+/-8.9 (P=NS). The NOx levels were directly correlated with the insulin levels (Spearman's R=0.53, P=0.008). CONCLUSION: Baseline plasma levels of NOx were significantly lower in HUT(+) patients than in controls. However, since the expected increase in NOx values during HUT-induced syncope was not observed, the possible role of NO in vasovagal hypotension is uncertain.

Implantable cardioverter defibrillators and Chagas' disease: results of the ICD Registry Latin America.

AIMS: Chagas' disease is an endemic parasitic affliction in Latin America. It is frequently associated with ventricular tachyarrhythmia and sudden death. The aim of this study is to assess the evolution of patients with Chagas' disease treated with an implantable cardioverter defibrillator (ICD). METHODS AND RESULTS: Eighty-nine chagasic patients with ICD were included for analysis from the Medtronic ICD Registry Latin America. At implant, mean age was 59 +/- 10 years, and 72% were male. Eighty-one patients (91%) had secondary prevention indications. Mean left ventricular ejection fraction was 40 +/- 11%, and mean follow-up was 12 +/- 7 months. During follow-up, six patients died (6.7%); three due to congestive heart failure, one due to sudden death, and two due to non-cardiac cause. Hospitalization occurred in seven patients. Thirty-eight patients (42%) received appropriate ICD therapies. A total of 737 episodes were detected by the ICD. The mean period between ICD implantation and the first appropriate therapy was 104 days. Electrical storms were observed in 14 of the 89 patients (15.7%). Inappropriate therapies were observed in seven patients. CONCLUSION: This registry confirms that ICD therapy provides protection by effectively terminating life-threatening arrhythmias in patients with Chagas' disease. This is especially so when patients receive the device for secondary prevention.

[New conduction disturbances and pacemaker indications after CoreValve® transcatheter aortic valve replacement. Incidence and follow up in a single center experience]. / Desarrollo de trastornos de conducción e indicaciones de marcapasos postimplante de válvula aórtica CoreValve® por vía endovascular. Incidencia y seguimiento en un solo centro.

INTRODUCTION: Transcatheter aortic valve implantation (TAVI) is currently reserved for patients with symptomatic aortic stenosis and high surgical risk. One major limiting factor related to TAVI procedural complications is conduction abnormalities and the need for permanent pacemaker implantation. OBJECTIVES: Evaluate the incidence of new conduction disturbances and pacemaker indications in patients with TAVI CoreValve® prosthesis (Medtronic Inc. Minneapolis, Minnesota, United States). METHODS: We included 28 patients, mean age 80 years. ECG parameters were evaluated previous and after implantation. All patients were monitorized during TAVI. Follow up Holter monitoring was performed at one, 6 and 12 months after the procedure and we also evaluated telemetry of implanted pacemaker. RESULTS: In previous ECG we found 7 patients had right bundle branch block and 7 patients had left bundle brunch block (LBBB). The post implant ECG showed 7 new LBBB: 3 during valvuloplasty and 4 on the end of it. Six patients required pacemaker implantation for permanent or paroxysmal complete AV block (CAVB). At one year follow up, 3 patients with LBBB during valvuloplasty had a normal ECG, one still had LBBB and one an asymptomatic CAVB found in Holter monitoring. CONCLUSIONS: Conduction abnormalities are frequent after CoreValve® aortic valve prosthesis implantation. The incidence of new LBBB was 25%. CAVB during or post TAVI require PM implantation. New LBBB may need a closer follow up because in a 3% of the cases it may progress to CAVB.

Insulin sensitivity in young women with vasovagal syncope.

BACKGROUND: Insulin, in addition to its known metabolic effects, has sympatho-excitatory and vasodilatory actions on muscular blood vessels. The goal of this study was to evaluate insulin sensitivity in young women with vasovagal syncope and positive tilt test results (HUT+) and to compare it with that in patients with negative tilt test results (HUT-) and in control subjects without a history of syncope. METHODS: Different indices of insulin sensitivity were obtained by an oral glucose tolerance test (OGTT) in 13 young women with syncope and HUT+ (age 26.8 +/- 9.1 years, body mass index 20.4 +/- 2.1), 8 patients with HUT- (age 26 +/- 5.6 years, body mass index 21.9 +/- 2.4), and 13 control subjects without syncope and HUT- (age 28.9 +/- 8.8 years, body mass index 23.1 +/- 1.7). The following parameters were assessed: fasting glucose and insulin levels (G(0), I(0)); G(0)/I(0) ratio; G(0) x I(0); areas under the curve for glucose and insulin; homeostatic model assessment (HOMA); quantitative insulin sensitivity check index (QUICKI); and composite whole-body insulin sensitivity index (ISI). RESULTS: G(0) and I(0) values were significantly lower in patients with HUT+ than in control subjects (G(0) 4.9 vs 81.9, P <.05, I(0) 4.7 vs 9.1, P <.005). All the fasting values-based indices (ie, HOMA 0.9 vs 1.9, P <.005) and the ISI (12.8 vs 7.1, P =.01) differed significantly in both groups. None of the parameters showed significant differences between patients with HUT- and control subjects. Sixty-one percent of patients with HUT+ had a vasovagal reaction during OGTT. CONCLUSIONS: Young women with vasovagal syncope and HUT+ have a greater insulin sensitivity. They have a propensity to reproduce symptoms during the OGTT. This hypersensitivity could be one of the predisposing factors for vasovagal episodes.

Automatic beat-to-beat left heart AV normalization: is it possible?

Programming the right heart AV interval to a normal value may cause a nonphysiological left heart AV due to interatrial and interventricular conduction delays, thus affecting cardiac performance. Since AV normalization at rest and exercise may be invalidated by pacing or sensing (mode) changes, the aim of this study was to (1) study the feasibility of a mode independent pacemaker (PM) algorithm for automatic beat-to-beat left AV normalization, (2) establish normal values for the time between mitral flow A wave (Af) and ventricular activation (Va), the AfVa interval, the mechanical surrogate of left AV, and (C) determine the range of values of the interatrial electromechanical delays (IAEMDs) and the effect of RA pacing. To pace with the proper right AV, the previously reported RV-paced interventricular electromechanical delay and the interatrial electromechanical delay, either P-sensed (IAEMDs) or atrial-paced (IAEMDp) are required inputs. Data were collected during diagnostic echo Doppler studies in 84 subjects divided in three groups: (1) control with narrow QRS and no structural heart disease (n = 33, age 50 +/- 21 years, 42% men); (2) patients in sinus rhythm with diverse cardiac pathologies except LBBB (n = 39, age 69 +/- 14 years, 56% men), and (3) DDD-paced patients (n = 12, mean age 71 +/- 6 years). Normal values of AfVa were established from the control group, while IAEMDs and IAEMDp and active atrial flow time (A-peak), in all subjects. The algorithm was tested by computer simulation under all possible modes with the following calculation: RAV = N + IAEMD - IVD, where RAV is the right AV, N is the desired normal AfVa value, IAEMD is either P-sensed or A-paced, and IVD is close to zero for intrinsic narrow QRS and biventricular pacing, or 79 ms for RV pacing. The results demonstrated (1) Normal (controls) AfVa: 85 +/- 15 ms (range 52-110 ms); (2) IAEMDs (All): 84 +/- 16 ms; (3) atrial pacing prolonged IAEMDs by 57 +/- 18 ms (from 93 +/- 15 to 150 +/- 25 ms, P < 0.0001); and (4) Computer simulation of rate and mode changes validated the normalization algorithm. An automatic, beat-to-beat left AV normalization algorithm to preserve a normal AfVa without a hemodynamic sensor is feasible. The normal value of AfVa is 85 +/- 15 ms.

Cardiodesfibrilador automático implantable: desfibrilación ventricular. Resultados de la experiência del ICD LABOR / Implantable automaitc ventricular defibrillator. Results of ICD LABOR Experiment

En la presente publicación se expone la experiencia acumulada por el ICD LABOR, un registro latinoamericano de cardiodesfibriladores implantables, en relación a la indución de fibrilación ventricular y los valores de umbral de desfibrilación durante el procedimento del implante. Sobre un total de 857 pacientes implantados entre Enero de 1995 y Octubre de 2004, se indujo fibrilación ventricular (FV) en 818 de ellos (95 por cento), con el propósito de comprobar la eficacia del sistema de detección y el nivel de energía requerido para revertir la arritmia. De los 39 pacientes restantes, en 2 individuos (0,23 por cento) la FV no pude ser inducida; mientras que en los otros 37 (4,77 por cento) el test de inducción no fue realizado. En el 74 por cento de los pacientes, uma energia de 15 J o menos suficiente para revertir la FV. En 42 sujetos fue empleada la máxima energía (30J), con fracaso de la reversión en 7 patients, que fueron rescatados mediante un choque externo. Los umbrales reales o verdaderos entre los tres principales grupos de patologías (enfermedad coronaria, enfermedad de Chagas y miocardiopatia dilatada idiopática), fueron semejantes y no pudo establecerse relaciones entre patología de base y necesidades de energía para la reversión de la FV. Trampoco se demostró relación entre el umbral ó verdadero de desfibrilación y la sobrevida durante el tiempo que duró el seguimiento

Cardiodesfibrilador automático implantable: Desfibrilación Ventricular. / Implantable automatic ventricular defibrilador. Results of ICD-Labor Experiment

En la presente publicación se expone la experiencia acumulada por el ICD-LABOR, un registro latinoamericano de cardiodesfibriladores implantables, en realación a la inducción de fibrilación ventricular y los valores de umbral de desfibrilación durante el procedimento del implante. Sobre un total de 857 pacientes impantados entre enero de 1995 y Octubre de 2004, se indujo fibrilación ventricular (FV) en 818 de ellos (95 por cento), con el propósito de comprobar la eficacia del sistema de detección y el nivel de energia requerido para revertir la arritmia. De los 39 pacientes restantes, en e individuos (0.23 por cento)la FV no pudo ser inducida; mientras que en los otros 37 (4.77 por cento), el test de inducción no fue realizado...

Registro latino-americano de cardiodesfibriladores do ICD registry: aspectos demográficos / Latin american cardiodefribrillator registry ICD registry: demographic aspects

Apresenta-se pela primeira vez na literatura mundial uma avaliação do acompanhamento de pacientes que receberam implante de cardiodesfibriladores na américa latina(ICD Registry - Medtronic Latin America). O resgistro é de vital importância para orientar condutas em cardiopatias de diferentes etiologias, tais como doença de chagas, miocardiopatia dilatada idiopática e coronariopatias...