Supraventricular Ectopy Research Articles

Holter electrocardiogram should be systematic in Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is due to mutations in the dystrophin gene on chromosomeXp21.1. Dystrophin is a sarcolemmal protein which binds actin to extra cellular matrix. A deficiency in dystrophin leads to breakdown of muscle membrane and muscular alteration [1]. The disease is clinically characterized by proximal weakness and wasting, leading to loss of ambulation by 12 years of age. The heart is affected to various degrees, depending on the stage of the disease. The most common cardiac abnormality in DMD is dilated cardiomyopathy. Conduction system disease and tachyarrhythmias may occur in some patients. Death occurs in early adulthood secondary to respiratory or cardiac failure [2], even if recent advances in the use of inspiratory and expiratory muscle aids have greatly reduced the risk of pulmonary morbidity and mortality rates [3].The typical initial manifestation of cardiac involvement in DMD is sinus tachycardia [1]. Cardiac involvement is due to progressive replacement of the cardiomyocytes and the Purkinje system by connective tissue or fat [1]. Impairment of cardiac autonomic function in patients with DMD is well known. Kirchmann found sinus tachycardia in 26% and reduced heart rate variability in 51% [4]. In human cardiac purkinje fibers, immunocytochemical staining showed that dystrophin was localised to the membrane surface of the purkinjer fiber [5]. The cardiac rhythm abnormalities play a significant role in morbidity and mortality in this disease [6]. Supraventricular ectopy or couplets are reported to indicate increasing severity of arrhythmia with the progression of disease [7]. 33% of DMD patients had ventricular premature beats in a study including 45 Duchenne muscular dystrophy patients without congestive heart failure and followed up for 3 years [8].

Nonlinear oscillator model reproducing various phenomena in the dynamics of the conduction system of the heart

A dedicated nonlinear oscillator model able to reproduce the pulse shape, refractory time, and phase sensitivity of the action potential of a natural pacemaker of the heart is developed. The phase space of the oscillator contains a stable node, a hyperbolic saddle, and an unstable focus. The model reproduces several phenomena well known in cardiology, such as certain properties of the sinus rhythm and heart block. In particular, the model reproduces the decrease of heart rate variability with an increase in sympathetic activity. A sinus pause occurs in the model due to a single, well-timed, external pulse just as it occurs in the heart, for example due to a single supraventricular ectopy. Several ways by which the oscillations cease in the system are obtained (models of the asystole). The model simulates properly the way vagal activity modulates the heart rate and reproduces the vagal paradox. Two such oscillators, coupled unidirectionally and asymmetrically, allow us to reproduce the properties of heart rate variability obtained from patients with different kinds of heart block including sino-atrial blocks of different degree and a complete AV block (third degree). Finally, we demonstrate the possibility of introducing into the model a spatial dimension that creates exciting possibilities of simulating in the future the SA the AV nodes and the atrium including their true anatomical structure.

Ambient particulate air pollution and cardiac arrhythmia in a panel of older adults in Steubenville, Ohio

Objectives: Ambient particulate air pollution has been associated with increased risk of cardiovascular morbidity and mortality. Pathways by which particles may act involve autonomic nervous system dysfunction or inflammation, which...

Supraventricular ectopy and recurrence of atrial fibrillation after electrical cardioversion

Paroxysmal atrial fibrillation (AF) is usually preceded by a premature atrial complex (PAC). We hypothesized that patients with a high frequency of atrial ectopic activity after restoration of sinus rhythm following direct current cardioversion would be more likely to experience recurrence of AF. Forty-four patients with documented persistent AF were studied. A 24 h Holter recording was performed from the day of external direct current cardioversion. Patients were reviewed at 1 week, 1 month, and 6 months. After 6 months, 59% of patients had experienced a recurrence of AF. Neither the frequency of PACs nor the frequency or duration of supraventricular tachycardia (SVT) episodes predicted AF recurrence (P=0.60, 0.30, and 0.42, respectively). There was a trend towards maximum rate of SVT predicting recurrence of AF (P=0.08). Frequency of supraventricular ectopy or the number and length of SVT runs in the 24 h after restoration of sinus rhythm are not strong predictors of recurrence of AF after electrical cardioversion. A larger study would be required to detect a small predictive effect.

Chronotropic incompetence in young patients with late postoperative atrial flutter: a case-control study

Atrial flutter causes late postoperative morbidity in congenital heart disease (CHD). Sinoatrial node dysfunction is associated with late postoperative atrial flutter, but pacing interventions driven by minimum heart rates (HR) have yielded mixed results. A retrospective case-control study was used to test the hypothesis that late postoperative atrial flutter is associated with chronotropic incompetence in active young CHD patients. Control CHD patients aged < or =18 years without documented supraventricular ectopy (n = 42) were matched with 42 patients (cases) having atrial flutter onset > or =6 months postoperatively. Minimum, average, and maximum non-flutter HRs were obtained from outpatient ambulatory 24 h ECG (Holter) recordings and graded exercise tests. Chronotropic competence was assessed using percentage of age-specific predicted maximum HR achieved, and calculated chronotropic index. Effects of rate-adaptive programming and maximum atrial pacing rates were analysed in 19 permanently paced cases. Least square estimates of minimum HRs were similar in cases and controls (54+/-2 vs. 52+/-2 bpm). Average HRs were lower in cases (75+/-2 vs. 81+/-2 bpm, P=0.02). Cases and controls differed most significantly with respect to percentage of predicted maximum HR achieved (67+/-2 vs. 80+/-2%, P < 0.001). This difference remained highly significant when the data were adjusted for age, sex, permanent pacing, and negatively chronotropic medication usage at the time of testing. Among paced patients, atrial flutter was significantly less likely to be observed in the setting of rate-adaptive pacing [odds ratio (OR) = 0.36; P < 0.05], and the likelihood of detecting atrial flutter decreased relative to the maximum programmed atrial pacing rate (OR 0.87 for every 5% increment in maximum pacing rate relative to maximum predicted HR for age; P < 0.05). Late postoperative atrial flutter is associated with chronotropic incompetence in paediatric CHD patients.

Safety of Exercise Stress Testing in Patients With Abnormal Concentrations of Serum Potassium

The objective of this study was to determine the safety of performing exercise stress testing in patients with abnormal serum potassium concentrations. Data were reviewed from 9,084 patients (mean age 63 +/- 12 years) referred for exercise echocardiography who had serum potassium measured <48 hours before the test were reviewed, and the occurrence of arrhythmias during stress testing was determined. Of 10,272 studies, 9,067 (88%) were in patients with normokalemia and 1,205 (12%) were in patients with abnormal serum potassium concentrations: 309 (26%) with hypokalemia (mean 3.4 +/- 0.16 mmol/L) and 896 (74%) with hyperkalemia (mean 5.1 +/- 0.19 mmol/L). Ventricular and supraventricular ectopy were common during exercise. Only 1 patient (potassium 4.9 mmol/L) had sustained ventricular tachycardia; all other episodes were nonsustained. Although ventricular and supraventricular ectopy are common during exercise testing, life-threatening arrhythmias are not. Exercise testing is generally safe despite mild to moderate hypokalemia or hyperkalemia.

Experience with an ambulatory 12-lead Holter recording system for evaluation of pediatric dysrhythmias

Background The 12-lead electrocardiogram demonstrates noninvasively many details concerning cardiac arrhythmias and their mechanism, but only for a limited period. A Holter system can record heart rhythm for a longer period, but shows 2 or 3 leads only. An ambulatory 12-lead Holter recording system combines the advantages of both. We report on our experience with the 12-lead Holter system in children. Study Population Twenty-four patients (age range, 3-22 years) underwent one or more 12-lead Holter recordings. Twelve patients had suspected or documented tachyarrhythmia, and 12 patients had suspected or proven long QT syndrome (LQTS). Results In the tachyarrhythmia group, 4 patients had supraventricular tachycardia and 7 ventricular tachycardia (VT). In the supraventricular tachycardia, group 1 patient had intra-atrial reentrant tachycardia with a single reentrant circuit, whereas another had multiple P-wave morphologies, suggesting multiple circuits. Two others had evidence for concealed atrioventricular accessory pathways. One patient had isolated supraventricular ectopy. In the VT group, 4 patients had uniform VT, and 3 patients had polymorphic VT. One patient with LQTS had macroscopic T-wave alternans. Two others showed intermittent extreme QT prolongation and T-wave notching during 12-lead Holter recording. Therapeutic Implications Patients with uniform VT underwent catheter ablation, guided in 2 instances by intracardiac pace mapping and comparison with the 12-lead Holter QRS morphology. All reentrant supraventricular arrhythmias with single P-wave morphology were ablated. One patient with intra-atrial reentrant tachycardia and multiple circuits received an antitachycardia pacemaker. In the LQTS group, the neonate with T-wave alternans received mexiletine in addition to β-blocker therapy. Conclusion In individual patients, the 12-lead Holter system provides important additional information about the arrhythmia and helps to plan appropriate therapy. Intermittent T-wave morphology changes can be diagnosed using 12-lead Holter recordings in patients with LQTS, allowing dynamic T-wave changes to be monitored. In specific cases, this may help identify patients with LQTS and also influence pharmacological therapy.

Spectrum and prognostic significance of arrhythmias on ambulatory Holter electrocardiogram in hypertrophic cardiomyopathy

The goal of this study was to assemble a profile and assess the significance of arrhythmias in a nontertiary-based hypertrophic cardiomyopathy (HCM) cohort. Hypertrophic cardiomyopathy is associated with arrhythmia-related consequences, particularly sudden death. Ventricular tachyarrhythmias on Holter electrocardiograms (ECG) have been reported as markers for sudden death in highly selected HCM populations. We assessed the profile of ventricular and supraventricular ectopy and bradyarrhythmia on ambulatory 24-h Holter ECG and also related these findings to clinical outcome in 178 HCM patients. Of the 178 study patients, 157 (88%) had premature ventricular complexes (PVCs), including 21 (12%) with >/=500 PVCs, 74 (42%) had couplets, 67 (37%) had supraventricular tachycardia (SVT), and 56 (31%) had nonsustained ventricular tachycardia (NSVT). Mean number of PVCs was 330 +/- 763 (range 1 to 5,435) and increased with age (p < 0.01); NSVT was associated with greater left ventricular hypertrophy (p = 0.01) and severe symptoms (New York Heart Association functional classes III and IV) (p = 0.04); SVT occurred more commonly in patients with outflow obstruction (p = 0.02). Over a follow-up of 5.5 +/- 3.4 years, 11 (6%) patients died suddenly (annual mortality rate, 1.1%) including 5 patients with NSVT. For sudden death, NSVT on Holter ECG had negative and positive predictive values of 95% and 9%, and sensitivity and specificity of 45% and 69%, respectively. In this nontertiary-based HCM cohort, ventricular and supraventricular tachyarrhythmias were particularly frequent and demonstrated a broad spectrum on ambulatory (Holter) ECG. Paradoxically, despite such a highly arrhythmogenic substrate, sudden death events proved to be relatively uncommon. Ventricular tachyarrhythmias had a low positive and relatively high negative predictive value for sudden death in this HCM population.

Cardiopulmonary events during hemodialysis: Effects of dialysis membranes and dialysate buffers

Adverse cardiac and pulmonary events are frequently observed during hemodialysis and contribute to significant morbidity and mortality. The temporal relationship between these events during the intradialytic period has not been well defined. To examine the event rate and timing of silent ischemia, cardiac ectopy, and hypoxemia, we conducted a prospective, single-blind, randomized study of 10 subjects undergoing maintenance hemodialysis with four contiguous combinations of dialysis membranes (cuprammonium or polysulfone) and dialysates (acetate or bicarbonate). The frequency of oxygen desaturation events peaked during the first 2 hours, whereas silent myocardial ischemia and supraventricular ectopies occurred more often in the later hours. Ventricular ectopy occurred steadily throughout the intradialytic period. The combination of acetate dialysis and cuprammonium membrane is associated with the most frequent events. We conclude that cardiopulmonary events can occur frequently during hemodialysis, and the frequency is dependent on the type of dialysis membrane and dialysate buffer used.

LEVOSIMENDAN ENHANCES CARDIAC PERFORMANCE IN PATIENTS UNDERGOING CARDIAC SURGERY

Introduction Levosimendan (L) is a new myofilament calcium sensitizer that has been shown to enhance left ventricular (LV) systolic and diastolic function and produce arterial and venous vasodilation in vivo. This investigation was designed to assess the safety and efficacy of L in enhancing cardiac performance after cardiopulmonary bypass (CPB) in patients undergoing cardiac surgery. Methods The hemodynamic and electrophysiologic effects of L were characterized in 18 patients undergoing cardiac surgery including CPB. After Institutional Review Board approval, the trial was carried out in a randomized, double-blind manner. Patients gave written, informed consent and were then randomized to receive either intravenous placebo, or low dose L (18 ug/kg bolus followed by a 0.2 ug/kg/min infusion), or high dose L (36 ug/kg bolus followed by a 0.3 ug/kg/min infusion). Placebo or L boluses were administered 15 min prior to separation from CPB and infusions were maintained for a total of 6 hours. Systemic and pulmonary hemodynamics were recorded at selected intervals before and after CPB. Pulmonary capillary wedge pressure was maintained between 10-15 mmHg with the infusion of intravenous crystalloid. Arterial blood gas tensions and plasma concentrations of L were obtained at selected intervals. ECG was continuously recorded by Holter monitoring (8 hrs preoperative to 30 hrs postoperative). Changes between placebo and experimental groups were assessed with Two-way ANOVA analysis with p<0.05 constituting statistical significance. Results Demographics, preoperative hemodynamics, type of surgery, and durations of aortic crossclamp and CPB were equivalent between groups. L significantly increased cardiac output in a dose dependent fashion (mean +/- SD data, Figure 1) Heart rate was not significantly increased while stroke volume increased with L. Systemic and pulmonary pressures and vascular resistances were reduced by L. Myocardial oxygen demand was not increased relative to control for low or high dose L. Blood gas tensions and shunt fraction were similar between groups. No significant alteration in the frequency of supra-ventricular and ventricular ectopy were observed.Figure 1Conclusion Levosimendan improves cardiac performance in patients undergoing cardiac surgery and CPB. It also appears safe by virtue of not causing dysrhythmias or tachycardia. Future trials will compare L to other therapies for hemodynamic support after CPB.

A comparison of cardiac rate-pressure product and pressure-rate quotient with Holter monitoring in patients with hypertension and cardiovascular disease: A follow-up report

Objectives. The purpose of this study was to evaluate patients with hypertension or cardiovascular disease, or both, for myocardial ischemia and cardiac arrhythmias while undergoing minor oral surgery. Study design. Sixteen patients were studied with noninvasive monitoring including heart rate, systolic, diastolic, and mean arterial blood pressure to calculate rate-pressure product (systolic blood pressure multiplied by heart rate) and pressure-rate quotient (mean arterial pressure divided by heart rate). These calculated measures were compared with the incidence of cardiac arrhythmias and ST segment depression recorded on a continuous Holter monitoring system. Results. Nine of 16 (56%) developed supraventricular or ventricular ectopy during dental extractions or minor preprosthetic surgery performed with local anesthesia 2% xylocaine with 1 100,000 epinephrine dilution. Three of the nine patients who experienced these arrhythmias had coincident abnormal rate pressure product and pressure-rate quotient values. None of these patients exhibited ST-T wave changes suggestive of myocardial ischemia. Atrial or ventricular ectopy suggests that myocardial irritability was more likely to occur than ischemia as measured by Holter monitoring and compared with abnormal rate pressure product and pressure-rate quotient values recorded.

Evaluation of Cardiac Rhythm Disturbances During Extravehicular Activity

This study represents the first systematic evaluation of dysrhythmias before, during, and after spaceflight including extravehicular activity (EVA). The data, based on 7 Shuttle crew members, revealed a nonsignificant decrease in ventricular and supraventricular ectopy during EVA, suggesting that the incidence of dysrhythmias is no greater during EVA than with any other phase of a mission or preflight.

Rhythm annotation and interobserver reproducibility of measures of heart rate variability

In summary, these data indicate that interobserver reproducibility is high for time domain and power spectral measures of heart rate variability, but that reproducibility is greater for the low-frequency measures, and especially for SDANN, than for the high-frequency measures. Overall interobserver variability of <8% for these measures is largely (50% to 75%) explained by interobserver differences in annotation of supraventricular ectopy and sinus arrhythmia.

Lack of proarrhythmia as assessed by Holter monitor after atrial radiofrequency ablation of supraventricular tachycardia in children

The purpose of this study was to assess the short-term arrhythmogenicity of atrial radiofrequency (RF) ablation lesions in children. Patients with the greatest exposure to RF energy comprised the study group. Holter data on 35 RF ablation procedures in 31 patients with a median age of 13.2 years (range 3 months to 20 years) was retrospectively analyzed. Patients received an average of 19.9 (SD = 13.6) RF lesions, all delivered by an atrial approach. Supraventricular ectopy and ventricular ectopy were compared immediately before and after and 4 to 9 weeks after RF ablation by serial Holter monitoring. Factors thought to possibly predispose patients to a proarrhythmic effect were used to define subgroups for separate analysis. No increase in ambient supraventricular ectopy or ventricular ectopy was observed either immediately after or 4 to 9 weeks after RF ablation compared with the baseline Holter recordings. Children exposed to relatively large doses of RF energy may demonstrate transient and asymptomatic nonsustained tachycardias in the short term. However, no new sustained tachycardias and no increase in supraventricular or ventricular ambient ectopy are detected by short-term Holter monitoring.

Cardiac response of elderly adults to normal activities and aerobic walking.

To assess the cardiac response of elderly adults, three sedentary men and six women (M = 68 years) with no known cardiovascular disease had their cardiac responses to activities done in a laboratory setting (walking, climbing stairs, carrying bags, shuffleboard); normal daily activities and aerobic walking (pace at 60% of the age-adjusted heart rate) were assessed by a 24-hour holter monitor. Supraventricular and ventricular ectopies were common during the 24 hours of monitoring, but none occurred during any of the activities. Bradycardia occurred at night, along with some supraventricular and ventricular ectopy, none clinically significant. Heart rate increased as the intensity of the activity increased (e.g., 68/ minute for carrying 5 pounds of groceries to 90/ minute during aerobic walking). When prescribing exercise or activity limitations, the chronotropic effects of usual daily activities must be considered in counseling sedentary, apparently healthy older adults.

Prognostic value of electrocardiographic monitoring of patients with severe diphtheria.

The clinical, the 12-lead, and the 24-hour electrocardiographic findings in 15 consecutively studied Vietnamese children (aged 7 months to 16 years) with severe diphtheria were documented. Five patients died, three from respiratory arrest and two from cardiogenic shock; one of these two patients had complete heart block that necessitated insertion of a pacemaker. Electrocardiographic abnormalities were detected by 24-hour monitoring in all 15 cases, even though most patients had no clinical signs of myocarditis. Rates of supraventricular and ventricular ectopy were elevated and remained high long after other clinical manifestations were no longer noted. The degree of ventricular ectopy at the time of presentation was significantly associated with fatal outcome. In this series, more than two ventricular ectopic beats on a recording upon admission to the hospital predicted fatal outcome with 100% sensitivity and 100% specificity. A variety of nonsustained bradyarrhythmias and tachyarrhythmias were also observed up until discharge from the hospital. The time course of recovery from diphtheritic myocarditis is longer than has been appreciated previously.

1031–33 Intravenous Triiodothyronine in Patients with Advanced Heart Failure

Thyroid hormone metabolism is frequently abnormal in patients with advanced congestive heart failure (CHF), with low triiodothyronine (T3) levels associated with poor hemodynamics and increased mortality. Studies have suggested that intravenous (i.v.) T3 improves hemodynamics acutely in patients immediately post-bypass surgery. To assess the safety of i.v. T3 (which may have unique inotropic mechanisms) in CHF, 22 patients with class III or IV CHF were given an Lv. T3 bolus ± 6 hour infusion (total dose range 0.05 – 1.7 /.μg/kg) under hemodynamic and ECG monitoring. Basal metabolic rate (BMR) by indirect calorimetry and LVEF by echo were measured at baseline and 2–4 hours post dosing. No patient had angina or sustained supraventricular or ventricular ectopy and mean heart rate (HR) did not change significantly (94 ± 16 to 98 ± 13 bpm, p = NS), with only 3/22 patients having an increase in HR &gt; 10 bpm. There was no significant change in mean BMR (2221 ± 899 to 2449 ± 682 Kcal/day, p = NS) and only minimal change in mean core temperature (36.8 ± 0.4 to 37.3 ± 0.6°C, P = 0.007), reflecting a peak temperature 38.0–38.5°C in 4 patients. Cardiac output increased by &gt; 1.0 L/mm in 11/22 patients (&gt;50% increase over baseline in 8/22 patients) with no significant change in LVEF (22 ± 7 to 23 ± 6%, P = NS) or filling pressures. Acute intravenous T3 administration is well tolerated in patients with advanced CHF and has potential hemodynamic benefit warranting further investigation.

MCL1 and MCL6 Compared to V1 and V6 in Distinguishing Aberrant Supraventricular from Ventricular Ectopic Beats

Use of V1 and V6 has been suggested for distinguishing aberrant supraventricular from ventricular ectopy. For two decades, "modified" leads MCL1 and MCL6 have been widely used as V1 and V6 substitutes for bedside monitoring, but their use has never been validated. To determine the value of MCL1 and MCL6, 81 morphologically distinct wide QRS ectopic beats were recorded from 46 patients during cardiac electrophysiological study. As determined by the His-bundle electrogram, 31 of the ectopics were aberrant supraventricular, 50 were ventricular. A new criterion, measurement of QRS onset to the predominant peak or nadir of the complex, was valuable in diagnosing wide complexes in MCL6 and V6. An interval of 50 msec or less predicted aberrant supraventricular ectopy; an interval of 70 msec or more predicted ventricular ectopy. There was agreement between the modified and conventional precordial leads regarding which QRS patterns were useful in distinguishing aberrant supraventricular from ventricular ectopy. A greater proportion of wide complexes in MCL1 and V1 exhibited patterns useful in making the diagnosis compared to MCL6 and V6. Using well-established criteria, the proportion of correct diagnoses that was made from individual leads was: MCL1 = 86%, V1 = 85%, MCL6 = 72%, V6 = 67%. The bedside leads (MCL1 and MCL6) were not statistically different in diagnostic accuracy from their conventional lead counterparts (V1 and V6); however, MCL1 and V1 were superior to MCL6 and V6. When the new criterion was added to make the diagnosis from MCL6 and V6, no difference in diagnostic accuracy was present between the four leads.

Cardiac fibroma presenting with clinically significant arrhythmias in infancy

Supraventricular or ventricular ectopy has been reported in association with cardiac fibroma. We report two patients, one with acquired complete heart block and one with mixed ventricular and supraventricular arrhythmias associated with this rare tumor of the heart.

Cardiovascular rhythm effects of gamma recombinant DNA interferon

Twenty patients receiving recombinant DNA gamma interferon were prospectively assessed for cardiac rhythm disturbances. All patients were evaluated with baseline electrocardiograms, pretreatment ambulatory monitoring and ejection fraction determination. Each patient was then monitored continuously during drug administration. Quantitative ventricular ectopy was not increased, nor were average heart rate, maximal heart rate, or quantitative supraventricular ectopy when comparing baseline to during therapy parameters. Complex cardiac ectopy and noteworthy cardiac events (NCE) were defined and identified in 2/20 (10%) patients pretreatment, and in 8/18 patients (44%) with normal baseline tracings during treatment (p = .02). This difference was not apparent when corrected for total days monitored pre- and post treatment (p greater than .2). These consisted predominantly of nonsustained short duration ventricular tachycardia (seven of eight patients). We conclude that life threatening cardiac events are uncommon with gamma interferon therapy.