Stability of pacing indices and need for pacing in cardiac transplant patients over 1 year of follow-up.

BACKGROUND: A significant minority of cardiac transplant patients require permanent pacemaker (PPM) implant, primarily for sinus node dysfunction. The stability of pacing indices has not been determined in this unique patient population, and data regarding ongoing need for pacing are limited. METHODS: Pacing indices (sensing, threshold, and impedance) as well as the percentage of time patients required pacing were recorded, from 30 cardiac transplant patients that underwent PPM implant, over 1 year of follow-up. Repeated measure ANOVA (analysis of variance) was used to compare pacing indices and the percentage of time patients required pacing in each cardiac chamber (right atrium (RA) and right ventricle (RV)) and at different time points. RESULTS: There was no difference in sensing among the follow-up time points (p = 0.9). Thresholds at 3 months were significantly higher compared to the day of implant (p = 0.005) and the day after implant (p = 0.03). Impedances at implant were significantly higher compared to day 1 (p < 0.001), 3 months (p < 0.003), and 12 months (p < 0.001) post-implant. The mean percentage of RA pacing was 85 ± 6% the day after implant, 74 ± 6% at 3 months, and 80 ± 6% at 1 year (p = 0.17). CONCLUSION: In cardiac transplant patients, pacing impedances decrease and thresholds trend up in short-term follow-up, but subsequent sensing, threshold, and impedance remain stable at 1 year. This is comparable to the pattern observed among noncardiac transplant PPM recipients. The atrial pacing percentage was stable over 1 year, suggesting continued relative sinus node dysfunction.

Reconocimiento electrocardiográfico de una dextrocardia / Recognition electrocardiographic a dextrocardia

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Latino children's body mass index at 2-3.5 years predicts sympathetic nervous system activity at 5 years.

BACKGROUND: To understand whether the relationship between young children's autonomic nervous system (ANS) responses predicted their BMI, or vice versa, the association between standardized BMI (zBMI) at 2, 3.5, and 5 years of age and ANS reactivity at 3.5-5 years of age, and whether zBMI predicts later ANS reactivity or whether early ANS reactivity predicts later zBMI, was studied. METHODS: Low-income, primarily Latino children (n=112) were part of a larger cohort study of mothers recruited during early pregnancy. Study measures included maternal prenatal weight, children's health behaviors (i.e., time watching television, fast food consumption, and time playing outdoors), children's height and weight at 2, 3.5, and 5 years, and children's ANS reactivity at 3.5 and 5 years. ANS measures of sympathetic nervous system (i.e., pre-ejection period) and parasympathetic nervous system (i.e., respiratory sinus arrhythmia) activity were monitored during rest and four challenges. Reactivity was calculated as the difference between mean challenge response and rest. Structural equation models analyzed the relationship between children's zBMI at 2, 3.5, and 5 years and ANS reactivity at 3.5 and 5 years, adjusting for mother's BMI, children's behaviors, and changes in height. RESULTS: There was no association between zBMI and ANS cross-sectionally. Children with high zBMI at 2 or 3.5 years or large zBMI increases from 2 to 3.5 years of age had decreased sympathetic activity at 5 years. Neither sympathetic nor parasympathetic reactivity at 3.5 years predicted later zBMI. CONCLUSIONS: Increased zBMI early in childhood may dampen young children's SNS responses later in life.

Alternancia eléctrica, patrón electrocardiográfico en el diagnóstico de enfermedad cardiaca grave / Electrical alternans, electrocardiogram pattern in the diagnosis of a severe heart disease

La alternancia eléctrica es un amplio concepto que describe las variaciones, latido a latido, en la dirección, amplitud y/o duración de cualquier componente del electrocardiograma. Se asocia a taponamiento cardiaco, arritmias malignas y muerte súbita. Presentamos el caso de una paciente de 77 años con alternancia eléctrica a partir de la cual se llegó al diagnóstico de taponamiento cardiaco (AU)

Electrical alternans is a broad term that describes alternate-beat variation in the direction, amplitude and duration of any component of the ECG wave-form. It is associated with cardiac tamponade, serious ventricular arrhythmias, and sudden death. We present the clinical case of a 77-year-old female with electrical alternans, from which a diagnosis of cardiac tamponade was established (AU)

Atrial fibrillation: cure or treat?

Controversies exist with regard to the optimal management of atrial fibrillation (AF). Restoration and maintenance of sinus rhythm is a desirable goal in AF patients because the prevention of recurrences may improve cardiac function, relieve symptoms and should reduce the likelihood of adverse events. Pharmacological therapy for AF has been disappointing with unacceptable rates of AF recurrence and other proarrhythmic sequelae. Recent studies suggested that potential benefit of sinus-rhythm maintenance with respect to mortality may have been neutralized by harmful effects of currently available antiarrhythmic therapies. Because of the inefficacy and dangers with nonablative therapies currently available for maintaining sinus rhythm, alternative treatments are certainly desirable. Curative treatment of atrial fibrillation with catheter ablation is now a legitimate option for a large number of patients. In several studies AF ablation has consistently been demonstrated to be superior to antiarrhythmic medications for the maintenance of sinus rhythm. Nevertheless, many aspects of the therapy are still controversial and large-scale prospective studies are needed to confirm the efficacy and safety of this approach.

An unusual resolution of T-wave oversensing in an implantable cardioverter defibrillator in a child with long QT syndrome.

T-wave oversensing poses a clinical challenge often resulting in inappropriate therapies and shocks. T-wave oversensing can often be resolved by certain programmable adjustments while accepting a small risk of undersensing ventricular fibrillation. The following case depicts a girl with LQT whose transvenous defibrillator repeatedly demonstrated T-wave oversensing despite optimizing various programmable features and a separate pace/sense lead. Utilization of an LV epicardial pace/sense lead with stable R-waves affirmed an unusual resolution of T-wave oversensing and avoidance of inappropriate shocks.

Pacemaker therapy for early and late sinus node dysfunction in orthotopic heart transplant recipients: a single-center experience.

BACKGROUND: Sinus node dysfunction (SND) is a well-known early complication of orthotopic heart transplantation (OHT). Its incidence over the lifetime of transplant recipients is less well characterized. The goal of this study was to determine the incidence and timing of SND treated with a permanent pacemaker in a large cohort of OHT recipients. METHODS: The databases of the Yale University Heart Transplant and Electrophysiology Services were reviewed and cross referenced. Patients who received pacemakers for SND were identified for analysis. A total of 241 patients underwent OHT using biatrial anastamoses from 1984 to 2006. Two hundred sixteen patients, 149 men and 55 women, mean age 50.2 +/- 11.6 years, survived > 5 days post-OHT. These, minus 12 lost to follow-up, were included in the analysis. RESULTS: These 204 patients were followed in the Yale Heart Transplant Clinic and had yearly electrocardiograms and 24-hour ambulatory monitoring. Of these patients, 24 (four female, 20 male, mean age at transplant 49 +/- 12 years) were felt to have clinically significant SND and received a pacemaker. Fourteen patients received pacemakers within 30 days of OHT; 10 patients received pacemakers 45 to 4,329 days after OHT. CONCLUSIONS: Although frequently seen as an early complication of OHT, SND remains a risk throughout the lifetime of OHT recipients. Its mechanism is likely multifactorial, and whether this risk can be mitigated over the long term by newer techniques such as bicaval anastamoses remains to be established.

Resting respiratory sinus arrhythmia buffers against rejection sensitivity via emotion control.

Emerging evidence suggests that high resting heart rate variability in the respiratory frequency band, or respiratory sinus arrhythmia (RSA) may capture individual differences in the capacity to engage in situationally appropriate regulation of affect and behavior. The authors therefore hypothesized that high RSA may act as a protective factor against difficulties controlling negative affect and hostile behaviors in conflicts with romantic partners in highly rejection-sensitive individuals--a population otherwise vulnerable to these responses. Results were consistent with this hypothesis such that highly rejection-sensitive participants reported less emotion control and more hostility in conflicts only if they were also low in RSA. Furthermore, emotion control mediated the joint effect of rejection-sensitivity and RSA on hostile conflict behavior. These results are consistent with the argument that resting RSA is a marker of flexible responding in the context of highly emotional situations, and further suggest that it may serve as a protective factor particularly in vulnerable populations.

Efficacy and late recurrences with wide electrical pulmonary vein isolation for persistent and permanent atrial fibrillation.

AIMS: Early recurrences of atrial arrhythmia after wide electrically isolating ablation for atrial fibrillation (AF) are well described, but the long-term risk of recurrence for patients with persistent and permanent AF has not been studied in detail. METHODS AND RESULTS Fifty-six consecutive patients [45 men (80.4%), age 55.9 +/- 8.7 years] with persistent [39(69.6%)] or permanent [17(30.4%)] AF were followed for 21.6 +/- 8.8 months after ablation. Atrial fibrillation duration prior to ablation was 6.4 +/- 5.6 years. Electrically isolating lesions encircling the left and right pulmonary veins (PVs) in pairs were created. After 1.5 +/- 0.7 procedures, 48 (85.7%) had sinus rhythm (SR) at 21.6 +/- 8.8 months of follow-up: achieved with 1 procedure in 27 (56.3%) and without anti-arrhythmics in 30 (62.5%). Atrial fibrillation recurrence was observed in 69.6% after the first and 46.4% after the last procedure. Of those with late recurrences (>90 days) following the last procedure, most [18 (69.2%)] did not have early recurrences. Pre-procedural AF duration (P = 0.007) and female gender (P = 0.005) were independent predictors of recurrence following the last procedure. CONCLUSION: Circumferential PV isolation is effective in most patients with persistent or permanent AF. However, repeat procedures are frequently required. Late recurrences are common and not precluded by the absence of early post-procedural arrhythmias.

Electrocardiographic features of ventricular pacing lead in the middle cardiac vein vs. right ventricular apex in a patient with persistent left superior vena cava.

A 53-year-old woman with sinus node dysfunction underwent dual-chamber pacemaker implantation through a persistent left superior vena cava draining into the coronary sinus, which was detected at the time of implantation. We managed to fix the ventricular lead in the right ventricular (RV) apex by forming a clockwise loop in the right atrium. Inadvertently, the lead was placed in the middle cardiac vein resembling RV apical position under fluoroscopic guidance. The paced QRS complex showed a pattern of tall R in V(1) through V(3), RS in V(4) through V(5), and QS in V(6). The pacing lead was carefully manipulated back into the RV apex, with the paced QRS complex showing a pattern of right bundle branch block, rR' in V(1) through V(2), and QS in V(3) through V(6). Careful attention to the surface electrocardiogram helps in distinguishing the pacing site even in those patients showing a pseudo-right bundle branch block pattern with RV apical pacing.

Physiologic pacing for atrial fibrillation prevention in sinus node disease: long-term results.

BACKGROUND: Physiologic pacing has been demonstrated to be effective in preventing atrial fibrillation recurrences in patients with sinus bradycardia. Aim of the study was to evaluate long-term incidence of atrial fibrillation in a large population of patients affected by sinus node disease receiving physiologic pacing. Furthermore, predictors of arrhythmia recurrence and effect of pacing mode were investigated. POPULATION: Four hundred twenty-five patients (220 Male, 77 +/- 9 years) were retrospectively analyzed: implanted system was AAI in 20.5% and DDD in 79.5%. Thirty-four percent had atrial fibrillation before implant. RESULTS: Follow-up lasted on average 51 +/- 36 months (median 42, range 1 month-18 years). Sixty-six percent were on antiarrhythmic drug therapy. After 5 years, 89% survived, 74.5% had at least one episode of atrial fibrillation, 39.9% were submitted to electrical cardioversion, 67.2% were hospitalized because of cardiac causes, 33.3% developed permanent atrial fibrillation. Primary conduction system disease and valvular heart disease were independent predictors for atrial fibrillation recurrence. Preimplant atrial fibrillation predicted arrhythmia recurrence during the follow-up, but it did not predict development of permanent atrial fibrillation. AAI pacing, when compared with DDD, was associated to a lower rate of atrial fibrillation recurrences (AAI 28.7%, DDD 53.3%, P < 0.001). CONCLUSION: In spite of expected benefits of physiologic pacing, the development of atrial fibrillation and permanent atrial fibrillation were quite common. The additional benefits of multifunction pacemakers designed to prevent and treat atrial fibrillation should be evaluated in controlled studies.

Inadvertent malposition of a transvenous pacing lead in the left ventricle.

We report the case of inadvertent malpositioning of a pacemaker lead in the left ventricle. The lead went through an open foramen ovale from the right to the left atrium and through the mitral valve into the left ventricle. After a review of the literature, we decided to anticoagulate the patient and leave the electrode in place. During a follow-up period of 16 months, there were no clinical complications.

Fractal ventilation enhances respiratory sinus arrhythmia.

BACKGROUND: Programming a mechanical ventilator with a biologically variable or fractal breathing pattern (an example of 1/f noise) improves gas exchange and respiratory mechanics. Here we show that fractal ventilation increases respiratory sinus arrhythmia (RSA) -- a mechanism known to improve ventilation/perfusion matching. METHODS: Pigs were anaesthetised with propofol/ketamine, paralysed with doxacurium, and ventilated in either control mode (CV) or in fractal mode (FV) at baseline and then following infusion of oleic acid to result in lung injury. RESULTS: Mean RSA and mean positive RSA were nearly double with FV, both at baseline and following oleic acid. At baseline, mean RSA = 18.6 msec with CV and 36.8 msec with FV (n = 10; p = 0.043); post oleic acid, mean RSA = 11.1 msec with CV and 21.8 msec with FV (n = 9, p = 0.028); at baseline, mean positive RSA = 20.8 msec with CV and 38.1 msec with FV (p = 0.047); post oleic acid, mean positive RSA = 13.2 msec with CV and 24.4 msec with FV (p = 0.026). Heart rate variability was also greater with FV. At baseline the coefficient of variation for heart rate was 2.2% during CV and 4.0% during FV. Following oleic acid the variation was 2.1 vs. 5.6% respectively. CONCLUSION: These findings suggest FV enhances physiological entrainment between respiratory, brain stem and cardiac nonlinear oscillators, further supporting the concept that RSA itself reflects cardiorespiratory interaction. In addition, these results provide another mechanism whereby FV may be superior to conventional CV.

Superior left atrial approach to the mitral valve: incidence of postoperative arrhythmia.

BACKGROUND AND AIM OF THE STUDY: The superior left atrial approach to mitral surgery involves exposure of the mitral valve through a longitudinal, craniocaudally orientated incision in the roof of the left atrium. The study aim was to evaluate the incidence of postoperative arrhythmias following this procedure. METHODS: Fifty-nine patients underwent either mitral valve repair (n = 20), mitral valve replacement (n = 26) or an associated procedure (n = 13), including aortic valve replacement, coronary artery bypass grafting and atrial septal defect closure. Eight patients had undergone previous surgery on the mitral valve. Patients were classified according to their preoperative rhythm: sinus rhythm (SR), paroxysmal or chronic atrial fibrillation (AF), or permanent pacing. Changes in cardiac rhythm were evaluated postoperatively, after four weeks, and at late follow up (mean 23.8 months). RESULTS: Preoperatively, 24 patients had shown SR, 10 had paroxysmal AF, 24 had chronic AF, and one patient had permanent pacing. At the time of discharge, SR was recorded in 18 patients who had SR preoperatively, in seven who had paroxysmal AF preoperatively, and in one patient who had chronic AF preoperatively. At follow up, SR was seen in 19 patients with preoperative SR, in seven with paroxysmal AF preoperatively, and in two with chronic AF preoperatively. Four patients received permanent pacemakers postoperatively due to total heart block or bradycardia. CONCLUSION: The superior left atrial approach to mitral valve surgery appears to be safe as it maintains the sinus rhythm in a high proportion of patients postoperatively. In addition, it is not normally prone to technical complications.

[+Gx-tolerance by the Cosmonauts of ISS crews 1, 6-9 and visiting crews 1-7 aboard Soyuz vehicles].

Analysis of +Gx tolerance of 15 members of short-term ISS missions and 9 members of long-term ISS missions aboard the Soyuz vehicles showed good tolerance during insertion and satisfactory during descent provided the use of in-flight countermeasures and anti-g suit Kentaur inside the vehicle. Objective data about the tolerance of off-nominal +Gx (6.26 and 8.1 G) pointed to a more pronounced sinus tachycardia and tachypnea in a ballistic descent following long-duration weightlessness as compared with nominal. Physiological deviations were transient, functional by character. Cardiac arrhythmia was largely observed during return to Earth. Two cosmonauts were found to develop prognostically unfavorable ECG indications during off-nominal descent. Main factors in these deviations could be age (above 45) and existence of some individual specifics of cardiac rhythm regulation. These results emphasize the necessity of more careful screening of candidates older than 45 years, as weightlessness may impact their general condition and tolerance of g-loads during return to Earth.

Prevention of paroxysmal atrial fibrillation in patients with sinus bradycardia: role of right atrial linear ablation and pacing site.

INTRODUCTION: Right atrial linear lesions (RALL), either alone or in combination with antiarrhythmic drug therapy, may modify the substrate for maintenance of atrial fibrillation (AF). The aim of this prospective randomized study was to determine whether RALL provides additional benefit to right atrial appendage pacing (RAAP) and/or interatrial septum pacing (IASP) and drug therapy in patients with symptomatic paroxysmal AF and sinus bradycardia requiring permanent atrial pacing. METHODS AND RESULTS: Sixty-four patients (33 men and 31 women, mean age 73 +/- 10 years) completed the 6-month follow-up. Patients were randomized to either RALL (n = 33) or non-right atrial linear lesions (NRALL), and then to either IASP (n = 32) or RAAP (n = 32). Fifteen RALL patients were paced at the IAS and 18 at the RAA. Seventeen NRALL patients were paced at the IAS and 14 at the RAA. No statistical difference was observed with regard to the mean atrial tachyarrhythmia (AT) burden between NRALL (84 +/- 169 min/day) and RALL patients (202 +/- 219 min/day). Mean AT burden was significantly lower in the IASP group (70 +/- 150 min/day) than in RAAP group (219 +/- 317 min/day; P < 0.016). In the RALL group, the mean AT burden was 99 +/- 180 min/day in the IASP patients and 288 +/- 372 min/day in the RAAP patients (P < 0.046). In the NRALL group, no statistical difference in the mean AT burden was observed between IASP patients (46 +/- 117 min/day) and RAAP patients (130 +/- 211 min/day). CONCLUSION: The results of the present study indicate that RALL did not provide any additional therapeutic benefit to combined antiarrhythmic drug therapy and septal or nonseptal atrial pacing in patients with sinus bradycardia and paroxysmal AF.

[Assessment of the use of various cardiac pacing modes for selection of antiarrhythmic therapy for prevention of recurrent attacks of atrial fibrillation and flutter]. / Otsenka ispol'zovaniia razlichnykh rezhimov kardiostimuliatsii dlia opredeleniia protivoretsidivnoi antiaritmicheskoi terapii paroksizmov mertsaniia i trepetaniia predserdii

AIM: To determine optimal mode of transesophageal pacing for selection of appropriate antiarrhythmic therapy for prevention of attacks of atrial fibrillation and flutter in patients with ischemic heart disease. MATERIAL AND METHODS: Two hundred eighteen patients with ischemic heart disease and attacks of atrial fibrillation or flutter. Selection of antiarrhythmic drugs was carried out with the use of competitive, rapid, salvos of ultra rapid, and slowly accelerating ultra rapid modes of pacing. Results. Most effective and reproducible method for induction of attacks of atrial flutter and fibrillation was slowly accelerating ultra rapid mode of pacing. Average duration of positive clinical effect of preventive antiarrhythmic therapy selected basing on the results of this mode in patients with ischemic heart disease was 3.1-/+0.3 years. Unfavorable prognostic sign decreasing preventive effect of antiarrhythmic therapy was left atrial dilatation. CONCLUSION: Slowly accelerating mode of transesophageal pacing was most effective tool for selection of antiarrhythmic therapy aimed at prevention of attacks of atrial fibrillation and flutter in patients with ischemic heart disease.

Sympathetic restraint of respiratory sinus arrhythmia: implications for vagal-cardiac tone assessment in humans.

Clinicians and experimentalists routinely estimate vagal-cardiac nerve traffic from respiratory sinus arrhythmia. However, evidence suggests that sympathetic mechanisms may also modulate respiratory sinus arrhythmia. Our study examined modulation of respiratory sinus arrhythmia by sympathetic outflow. We measured R-R interval spectral power in 10 volunteers that breathed sequentially at 13 frequencies, from 15 to 3 breaths/min, before and after beta-adrenergic blockade. We fitted changes of respiratory frequency R-R interval spectral power with a damped oscillator model: frequency-dependent oscillations with a resonant frequency, generated by driving forces and modified by damping influences. beta-Adrenergic blockade enhanced respiratory sinus arrhythmia at all frequencies (at some, fourfold). The damped oscillator model fit experimental data well (39 of 40 ramps; r = 0.86 +/- 0.02). beta-Adrenergic blockade increased respiratory sinus arrhythmia by amplifying respiration-related driving forces (P < 0.05), without altering resonant frequency or damping influences. Both spectral power data and the damped oscillator model indicate that cardiac sympathetic outflow markedly reduces heart period oscillations at all frequencies. This challenges the notion that respiratory sinus arrhythmia is mediated simply by vagal-cardiac nerve activity. These results have important implications for clinical and experimental estimation of human vagal cardiac tone.