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Purpose: The safe delivery of cardiac radioablation (CR) for atrial fibrillation (AF) is challenged by multi-direction target motion, cardiac rate variability, target proximity to critical structures, and the importance of complete target dose coverage for therapeutic benefit. Careful selection of appropriate treatment procedures is therefore essential. This work characterizes AF cardiac radioablation target motion and target proximity to surrounding structures in both healthy and AF participants to guide optimal treatment technique and technology choice. Methods: Ten healthy participants and five participants with AF underwent MRI acquisition. Multi-slice, cardiac-gated, breath-hold cines were acquired and interpolated to create three-dimensional images for 18-30 cardiac phases. Treatment targets at the left and right pulmonary vein ostia (CTVLeft and CTVRight respectively) and adjacent cardiac structures were contoured and their displacements throughout the cardiac cycle were assessed. Target proximity to surrounding structures were measured. Free-breathing real-time two-dimensional cine images were also acquired at 4 Hz frequency for between 1- and 2-min duration. The motion of easily identifiable points within the target, diaphragm and sternum was measured to assess respiratory motion. Results: Target motion due to cardiac contraction was most prominent in the medial-lateral direction and of 4-5 mm magnitude. CTVRight displacements were smaller in participants with AF than healthy participants in normal sinus rhythm. Nearby cardiac structures often moved with different magnitudes and motion trajectories. CTVLeft and/or CTVRight were in direct contact with the esophagus in 73% of participants. Target motion due to respiration was most prominent in the superior-inferior direction and of 13-14 mm magnitude in both healthy and AF participants. Conclusion: AF CR target motion and relative displacement was characterized. The combination of target motion magnitude and relative displacement to critical structures highlights the importance of personalizing motion compensation techniques for effective AF CR treatments.

A 59-year-old female underwent a dual-chamber pacemaker implantation for intermittent complete heart block. A baseline electrocardiogram showed normal sinus rhythm with first-degree atrioventricular (AV) block and right bundle branch block. A His bundle lead placement was attempted. An intracardiac electrogram from the His bundle lead demonstrated atrial-His, and His-ventricular intervals were 186 and 110 ms, respectively. Pacing was performed from the His bundle lead with a decremental pacing output to assess for the His bundle capture threshold. However, there were no significant QRS morphology changes during the pacing. Is the His bundle captured? The tracing evaluation demonstrated the fascinating physiology of activation wavefront in His Purkinje system that could be applied in the use of conducting system pacing technologies.

INTRODUCTION Atrial fibrillation is often asymptomatic and un-diagnosed in the community resulting in an increased risk of heart failure and stroke to those patients. We evaluated the effectiveness, tolerability, and accuracy of a novel six-channel electrocardiogram digital-health screening device, the RhythmPad, for the detection of atrial fibrillation. METHODS Seven hundred and fifty-two participants attending the cardiology department were recruited. Two recordings were taken-a six-lead electrocardiogram using the RhythmPad device and a standard 12-lead electrocardiogram. Recorded traces were analyzed by two blinded cardiologists. The computer-generated automated diagnostic reports from both systems were also compared. Post-participation feedback was obtained from study participants using a three-part questionnaire. RESULTS The sensitivity of the six-lead electrocardiogram compared to the 12-lead electrocardiogram, analyzed by two blinded cardiologists, for the detection of normal sinus rhythm was 95.9%, with a specificity of 97.2%. The sensitivity for the detection of atrial fibrillation using the six-lead ECG was 93.4%, with specificity 96.8%. The six-lead automated diagnostic report had a sensitivity and specificity of 97.5% and 98.6%, respectively, for correctly diagnosing normal sinus rhythm. For the correct diagnosis of atrial fibrillation, the six-lead automated diagnostic report had a sensitivity and specificity of 95.4% and 98.8%, respectively. A total of 95.4% of participants found RhythmPad to be comfortable, with only 0.5% preferring the 12-lead ECG device in comparison to six-lead ECG acquisitions. CONCLUSION The RhythmPad digital health device and its automated diagnostic report were highly accurate in detecting atrial fibrillation when compared to a standard 12-lead electrocardiogram.

BACKGROUND Tiletamine-zolazepam is a widely used as an alternative chemical immobilization method in non-human primates, with a safe application pathway and necessary relaxation. In order to determine the electrocardiographic parameters of Sapajus libidinosus after intramuscular tiletamine-zolazepam administration at the dose of 5 mg/kg, nine animals were submitted to anesthesia. METHODS The interpretation of the electrocardiogram determined: heart rate in bpm and heart rhythm, P wave, P-R interval, R wave, QRS complex, T wave, Q-T interval, corrected QT interval and electrical axis. The mean HR was 206 ± 32 bpm. RESULTS The majority of the monkeys showed normal sinus rhythm, but one animal showed sinus tachycardia. The most commonly observed electrical axis was between +30° and +90°. Two animals presented bigger alterations in the tracing such as low amplitude QRS and T wave bigger than 1/4 of the R wave. CONCLUSIONS The administration of tiletamine-zolazepam was safe and efficacious, with minimal cardiovascular effects.

Grading severity of AS in AF is complicated by varying stroke volumes associated with fluctuating maximum velocities and pressure gradients across the aortic valve. Current guidelines recommend averaging five continuous-wave peak velocity and mean gradient (MG) Doppler signals across the aortic valve when estimating severity of AS in AF. However, it is unknown when grading severity of AS how the average of multiple Doppler signals vs the highest Doppler signal in AF compares to the Doppler signals when the patient is in normal sinus rhythm. We present a series of patients with AS who had two echocardiograms performed within 2-4 months of each other, one when in normal sinus rhythm and one when in AF, and compare the aortic valve hemodynamics associated with the two rhythms.

This paper presents a new approach for biometric personal identification based on electrocardiogram (ECG) features. ECG, which reflects cardiac electrical activity, is a distinctive characteristic of a person and can be used for security needs. Twenty-one features based on temporal and amplitude distances between detected fiducial points and 10 morphological descriptors are extracted from each heartbeat. Then, support vector machine (SVM) is used as a classifier. A comparative study between two kernels, Gaussian and polynomial, was made in order to determine the best kernel and the appropriate values of hyperparameters that improve the recognition performance. The algorithm is evaluated using two databases, namely MIT-BIH Arrhythmia and MIT-BIH Normal Sinus Rhythm. Analysis of the results shows that the combination of all features allows improvement of our system efficiency with regard to healthy human subjects and those with arrhythmia. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

QT Interval Readings With a Smartphone Heart MonitorIntroduction A variety of medications ranging from antiarrhythmics to psychotropics, as well as conditions such as bradycardia, can prolong the QT interval, increasing the risk for life-threatening arrhythmias. Monitoring the corrected QT interval (QTc) is therefore critical for patient safety. The recent development of smart phone heart monitors (SHM) may allow for easier QTc monitoring. We sought to evaluate the accuracy of an SHM for assessing the QTc, as compared to the standard 12-lead ECG. Methods and Results We compared the QTc interval in lead-I and lead-II between an SHM and 12-lead ECG. Healthy volunteers and hospitalized patients in sinus rhythm being loaded on dofetilide or sotalol were included. Manual and automatic measurements were studied. Across 99 healthy volunteers, the SHM QTc demonstrated good agreement (bias = 4 milliseconds, standard deviation of bias = 11 milliseconds) compared to the 12-lead ECG, using the Bland–Altman method of agreement. Across all hospitalized patients, the SHM was capable of demonstrating QTc prolongation. Between the 12-lead ECG and SHM, lead-I measurements had reasonable agreement (bias = 3 milliseconds, standard deviation of bias = 46 milliseconds). A QTc of > 500 milliseconds was associated with a higher likelihood (OR = 12.0; 95% CI 1.5–111.4; P = 0.02) to not achieve perfect agreement. Conclusion The SHM is accurate in measuring QTc interval in sinus rhythm when compared to 12-lead ECG in healthy volunteers. For patients receiving QT prolonging antiarrhythmics, SHM is capable of detecting QTc prolongation, and lead-I of the SHM is most accurate in measuring the QTc if < 500 milliseconds.

Electrical cardioversion (EC) for atrial fibrillation (AF) is a common procedure performed in an attempt to restore normal sinus rhythm (NSR). Many factors predict long-term maintenance of NSR and the risk of AF recurrence. The duration of AF, cardiac size and function, rheumatic heart disease, significant mitral valve disease, left atrial enlargement, and older age are among the most common recognized factors. A number of interventions can potentially decrease the AF recurrence rate. Identifying and treating reversible causes and the use of antiarrhythmic medications in certain situations can help decrease the risk of AF recurrence. The role of the newer anticoagulants is expanding, and wider application is expected in the near future. We hope that this summary will serve as a guide to physicians and healthcare providers to address the question of who should undergo cardioversion, as there are patients who are most likely to benefit from this procedure and others that will revert back into AF within a short period. To identify who would benefit most from EC and have a reasonable chance of long-term maintenance of NSR, a thorough evaluation of each individual patient should be performed to tailor the best therapy to each individual.

Background The term “permanent” atrial fibrillation (AF) is generally used to describe the rhythm status of patients for whom cardioversion has failed or attempts to restore normal sinus rhythm (NSR) have ceased. However, the rhythm status of such patients is typically assessed by symptoms or intermittent monitoring, and therefore categorization may be imprecise. Methods We evaluated the presence of NSR among patients who were identified by their physicians as having permanent AF and who underwent prior insertion of a cardiac rhythm management device in the OMNI study. Patients with a dual- or triple-chamber device (pacemaker, implantable cardiac defibrillator, or cardiac resynchronization therapy) and ≥30 days of device data were studied. We tabulated the percentage of follow-up days spent entirely in NSR, entirely in AF, or in both NSR and AF. Results A total of 69 patients met inclusion criteria and were followed for 767 ± 479 days. More than 73% of patients experienced ≥1 entire day in NSR. On average, 38.2% of days were spent entirely in NSR, 11.8% of days were spent in a combination of NSR and AF, and only 50.0% of days were spent entirely in AF. The median daily AF burden during follow-up was 14.6 [1.1–23.7] hours/day. Conclusions NSR is common in many device patients thought to have permanent AF, suggesting that continuous arrhythmia monitoring could be useful in identifying permanent AF patients who may benefit from renewed rhythm control efforts. Alternatively, some permanent AF patients undergoing atrioventricular nodal ablation may benefit from dual-chamber devices due to likely periods of NSR.

Background: Biphasic pacing is a novel mode of pacing that was suggested to increase cardiac conduction velocity as compared with cathodal monophasic pacing. We aimed to evaluate the safety and efficacy of rapid atrial pacing to convert atrial fibrillation (AF) to normal sinus rhythm. Methods: Multiple biphasic (anodal/cathodal), reverse biphasic (cathodal/anodal), and monophasic (cathodal) atrial pacing therapies were performed among 12 patients undergoing left atrial catheter ablation for AF. The efficacy end point was successful conversion of AF to sinus rhythm, and safety end point no induction of ventricular arrhythmias. Patients were paced at three cycle lengths (100, 200, and 333 msec) for 60 seconds at three locations (right and left atrial appendages and coronary sinus). Results: Among the 66 biphasic (anodal/cathodal) pacing procedures one procedure in a patient with chronic AF, which involved pacing at the left atrial appendage with a cycle length of 200 msec, led to conversion of AF to sinus rhythm. None of the 66 monophasic pacing procedures or the 66 reverse biphasic (cathodal/anodal) pacing procedures was associated with AF termination. None of the biphasic pacing procedures was associated with induction of ventricular arrhythmias. Conclusions: Rapid atrial pacing using a variety of waveforms at the cycle length and output used in the current study was found to be safe. There was a single success in converting a chronic AF to sinus rhythm. Ann Noninvasive Electrocardiol 2012;17(1):22–27

Objectives: This study was designed to determine the safety and efficiency of asymmetric and symmetric ventricular septal occluders (AVSDOs and SVSDOs, respectively) for closure perimembranous ventricular septal defect (PMVSD) in children. Methods: Between January 2003 and December 2007, 142 children with PMVSD were treated with occluders (64 with AVSDOs and 78 with SVSDOs). Results: The defect diameter was 5.3 ± 1.1 mm in the AVSDO group and 5.4 ± 1.3 mm in the SVSDO group (P > 0.05). The success rates were similar between two groups [93.8% (AVSDO) vs. 94.9% (SVSDO), P > 0.05]. Two patients in the AVSDO group were switched to the SVSDO group due to residual shunts, and one patient in the SVSDO group was switched due to aortic regurgitation after deployment of the occluder. After procedure, 17 patients [seven with AVSDOs and nine with SVSDOs (P > 0.05)] developed various types of heart block (HB). Among them, 13 patients converted to the normal sinus rhythm. The remaining four cases had not recovered at the end of the study. Conclusions: Transcatheter closure of PMVSD using both AVSDO and SVSDO was safe and effective. Development of HB was the main complication for both devices. © 2010 Wiley-Liss, Inc.

Background: Tissue Doppler imaging (TDI) of mitral (MA) and tricuspid annulus (TA) events characterizes systolic and diastolic properties of each respective ventricle. However, the effect of chronic pulmonary hypertension (cPH) on these TDI annular events has not been well described. Methods: Measurements of right ventricular (RV) performance with TDI of the lateral mitral and tricuspid annuli, to measure isovolumic contraction (IVC) and systolic (S) signals were recorded from 50 individuals without PH and from 50 patients with cPH. To avoid confounding variables, all patients had normal left ventricular ejection fraction and were in normal sinus rhythm at the time of the examination. Results: As expected, markers of RV systolic performance were markedly reduced while LV systolic function remained largely unaffected in cPH patients when compared to patients without PH. TDI interrogation of the MA revealed lengthening of the time interval between IVC and systolic signal (70 ± 17 msec) when compared to individuals without PH (43 ± 8 msec; P < 0.0001). In contrast, cPH markedly shortened the time interval between IVC and the TA systolic signal (34 ± 12 msec) when compared to individuals without PH (65 ± 17 msec; P < 0.0001). Conclusions: cPH lengthens time interval between the IVC and the MA systolic signal while shortening this same interval when the TA is interrogated with TDI; reflecting the potential influence that cPH exerts in biventricular performance. Whether measuring these intervals be routinely used in the follow-up of cPH patients will require further study. (Echocardiography 2010;27:969-976)

In three patients admitted to hospital after ingestion of an overdose of chloral hydrate, the ECG showed supraventricular and ventricular tachyarrhythmias. The possible mechanism for the arrhythmias may be an enhanced automaticity of supraventricular and ventricular pacemaker cells caused by metabolites of chloral hydrate. The ventricular arrhythmia responded to i.v. treatment with lignocaine in one patient, and to phenytoin in another in whom lignocaine failed to restore a normal sinus rhythm.

Atrial fibrillation (AF) is an increasingly important disorder. In most patients the treatment of AF usually employs anti-arrhythmic drugs (AADs). Despite the widespread utilization of AADs for the conversion of atrial fibrillation and maintenance of normal sinus rhythm, their use is limited by modest efficacy, frequent intolerance, and the potential for serious ventricular proarrhythmia and organ toxicity. In addition to AADs, ablations for AF have come into vogue. If ablation techniques improve, one might ask whether there will still be a role for AADs, and, if so, what will it be and what agents will be used. This manuscript will attempt to answer these questions.

• ATRIAL FIBRILLATION (AF) is the most common sustained disturbance of cardiac rhythm, affecting an estimated 2.3 million people in North America and 4.5 million people in the European Union. • ALTHOUGH AF IS ASSOCIATED with significant morbidity, mortality, and increased health care costs, more-precise and less-invasive surgical ablation procedures have been developed. Specific cardiac sites emitting the aberrant, premature electrical signals that induce AF are ablated, which results in excellent cure rates and allows normal sinus rhythm to resume. • THESE PROCEDURES can be performed with or without the use of cardiopulmonary bypass, through either traditional sternotomy or minimally invasive thoracotomy incisions. AORN J 86 (July 2007) 23-40. © AORN, Inc, 2007.

Premature ventricular contractions (PVC) trigger muscle sympathetic nerve activity (MSNA) of greater amplitude and duration compared to MSNA in normal sinus rhythm (NSR). The increase is usually at...

‘Cardiac memory’ describes an electrocardiographic T wave vector change, recorded during normal sinus rhythm that reflects the QRS complex vector during prior periods of ventricular pacing or arrhythmia. In this brief review we consider the mechanisms responsible for cardiac memory, which offer a unique window for relating molecular determinants of repolarization to their expression in the function of ion channels and in the electrophysiology of the heart. Understanding the steps that translate the molecular mechanisms for memory into clinical expression in this relatively straightforward model facilitates our comprehension of the complex pathways that order normal cardiac repolarization and repolarization changes.

The popularity of amiodarone has grown due to its effectiveness in converting arrhythmia and its formulation availability. Formulations of the drug also contain iodine; the iodine content is 75 mg in a 200-mg tablet of amiodarone and 18.7 mg/ml in the intravenous solution. Approximately 10% of the iodine content of oral amiodarone is released into the circulatory system and may increase the risks of hypersensitivity reactions in iodine-sensitive patients. Documented allergies to contrast media or shellfish should not imply that a patient is allergic to iodine. Reactions to contrast media are likely due to the high osmolar or ionic content of the dye. The primary allergen in shellfish that stimulates allergic reactions is tropomyosin. Although amiodarone can cause thyroid disorders due to the high iodine load delivered to the body with each dose, no known association exists between amiodarone and reactions to contrast media or shellfish. Three patients whose medical charts listed an allergy to iodine were administered amiodarone for chemical cardioversion of arrhythmia to normal sinus rhythm. No anaphylactic or anaphylactoid reactions were observed in any of the patients during oral or intravenous amiodarone administration. In patients with true iodine hypersensitivity, however, the potential for such reactions exists.

Linear Lesions Prevent Atrial Fibrillation.Introduction: In the animal model, segmentation of the atria with radiofrequency-generated linear lesions (LL) using the loop catheter has been shown to be highly effective in terminating chronic atrial fibrillation (AF). This study addresses the question whether the same lesion set also would prevent reinduction and sustainability of AF. Methods and Results: We studied two groups of dogs. The AF group included eight dogs in which the atria were paced until chronic AF was present. After 6 months of sustained AF, the dogs were converted to normal sinus rhythm (NSR) by the creation of LL in both atria. Rapid atrial pacing was restarted 6 months later and continued for 4 weeks. In the NSR group, there were nine dogs in NSR without inducible AF at baseline. LL were created, and after 6 months rapid atrial pacing was applied for 4 weeks. Rhythm status was monitored weekly. Transthoracic echocardiography was performed at baseline, before linear lesion placement, and before pacing/repacing. At the conclusion of the study, the hearts were excised and examined. The lesions were stained, and their quality was assessed. AF was induced in a much shorter interval in the dogs in which AF had previously been present than in NSR dogs (8 ± 5 days vs 25 ± 13 days; P < 0.05). LL prevented sustainability of AF induced via rapid pacing once the pacing stimulus was stopped. Incomplete lesions were associated with increased inducibility of atrial tachycardia and AF. Conclusion: In this animal model of AF, LL are not only capable of terminating chronic AF, but also lead to self-termination of AF once the rapid pacing is stopped. Self-termination of AF after induction with rapid pacing was not observed in this AF model in the absence of LL. In the dogs with 6 months of AF, the presence of AF led to increased atrial susceptibility to AF induction by rapid pacing, even with LL and after 6 months of recovery. Incomplete LL allows induction of atrial tachycardia and AF.

Forty-seven Presa canario dogs were diagnosed with congestive heart failure due to dilated cardiomyopathy (DCM). Supraventricular or ventricular tachydysrhythmias were found in 29 dogs. Atrial fibrillation was the most common dysrhythmia. Ventricular dysrhythmias were observed infrequently and had a very important prognostic value in Presa canario dogs with DCM. Abnormalities of cardiac conduction were diagnosed in 16 (34%) dogs and changes in wave morphology were found in 29 (62%) dogs. Normal sinus rhythm was recorded in only 12 (26%) Presa canario dogs with DCM.

Procainamide and T-Wave Alternans. Introduction: The measurement of microvolt level T wave alternans (TWA) is a technique for detecting arrhythmia vulnerability. Previous studies demonstrated that the magnitude of TWA is dependent on heart rate. However, the effects of antiarrhythmic drugs on TWA are unknown. Methods and Results: This was a prospective evaluation of intravenous procainamide on TWA in 24 subjects with inducible sustained ventricular tachycardia (VT). Measurements of TWA were performed at baseline in the drug-free state and after procainamide loading (1,204 ± 278 mg). Recordings were made in normal sinus rhythm, and during atrial pacing at 100 heats/min and 120 heats/min. The magnitude of TWA in the vector magnitude lead was decreased by procainamide at all heart rates: 0.6 ± 0.8 to 0.3 ± 0.4 μV in sinus rhythm, 2.0 ± 1.6 to 0.7 ± 0.7 μV at 100 beats/min, and 3.0 ± 2.0 to 1.7 ± 1.8 μV at 120 beats/min (P < 0.001 by analysis of variance). The sensitivity of TWA for the induction of VT at baseline was 5% in sinus, 60% at 100 beats/min, and 87% at 120 beats/min, while it decreased with procainamide to 5%, 19%, and 60%, respectively. Decreases in TWA in response to procainamide were independent of the antiarrhythmic effects on VT inducibility. Conclusions: These results indicate that the magnitude of TWA decreases with acute procainamide loading and this effect decreases the sensitivity of TWA for the induction of sustained VT.

The peak endocardial acceleration (PEA, unit g) shows a near correlation with myocardial contractility during the isometric systolic contraction of the heart (dP/dtmax), with sympathetic activity and, thus, with physiological heart rate modulation. The (Biomechanical Endocardial Sorin Transducer (BEST) sensor is incorporated in the tip of a pacing lead and measures PEA directly near the myocardium. In an international study, the lead was implanted with the dual chamber pacemaker Living-1 (Sorin) in 105 patients. The behavior of the PEA signal was tested under conditions of physical and mental stress and during daily life activities by 24-hour recordings of PEA (PEA Holter) at 1 to 2 months and approximately 1 year after implantation. Implantation of the BEST lead was performed without complications in all patients. The sensor functioned properly in the short- and long-term in 98% of patients. Although PEA values differed from patient to patient, the values closely reflected the variations in sympathetic activity due to physical and mental stress in each patient. During exercise and during daily life activities a close correlation between PEA and heart rate was observed among patients with normal sinus rhythm. Peak endocardial acceleration allows a nearly physiological control of the pacing rate.

Chronic atrial fibrillation (AF) had been documented in a patient with atrial septal defect for 7 years. A right atrial separation procedure was performed for ablation of chronic AF, concomitant with repair of the atrial septal defect, and followed by atrial electrophysiological mapping. A horizontal transectional incision extending to the borders of the atrial septum and the tricuspid annulus was made. Cryolesions of the atrial isthmus between the margin of the upper incision and the tricuspid valve annulus were created at -60 degrees C for 2 minutes at a time. After the operation, the patient had restored normal sinus rhythm during a subsequent follow-up period of 48 months.

The pressure phase plane (PPP), defined by dP(t)/dt versus P(t) coordinates has revealed novel physiologic relationships not readily obtainable from conventional, time domain analysis of left ventricular pressure (LVP). We extend the methodology by introducing the normalized pressure phase plane (nPPP), defined by 0 ≤ P ≤ 1 and −1 ≤ dP/dt ≤ +1. Normalization eliminates load-dependent effects facilitating comparison of conserved features of nPPP loops. Hence, insight into load-invariant systolic and diastolic chamber properties and their coupling to load can be obtained. To demonstrate utility, high-fidelity P(t) data from 14 subjects (4234 beats) was analyzed. PNR, the nPPP (dimensionless) pressure, where –dP/dtpeak occurs, was 0.61 and had limited variance (7%). The relative load independence of PNR was corroborated by comparison of PPP and nPPP features of normal sinus rhythm (NSR) and (ejecting and nonejecting) premature ventricular contraction (PVC) beats. PVCs had lower P(t)max and lower peak negative and positive dP(t)/dt values versus NSR beats. In the nPPP, +dP/dtpeak occurred at higher (dimensionless) P in PVC beats than in regular beats (0.44 in NSR vs. 0.48 in PVC). However, PNR for PVC versus NSR remained unaltered (PNR = 0.64; P > 0.05). Possible mechanistic explanation includes a (near) load-independent (constant) ratio of maximum cross-bridge uncoupling rate to instantaneous wall stress. Hence, nPPP analysis reveals LV properties obscured by load and by conventional temporal P(t) and dP(t)/dt analysis. nPPP identifies chamber properties deserving molecular and cellular physiologic explanation.

UNLABELLED Automatic mode switching (AMS) is absolutely dependent on atrial tachyarrhythmia detection. The effects of programming several features that could influence tachyarrhythmia detection were assessed in 18 patients (six women; mean age 64 years) with pacemakers having AMS capability. The atrial electrogram amplitude in sinus rhythm at implant (SR-EGM), last measured atrial sensing threshold prior to tachycardia (A-SENS), and atrial sensing threshold for effective AMS during atrial tachyarrhythmia (AMS-SENS) were obtained. Additionally, ten patients had AV intervals increased from 60 to 200 ms, while seven patients had detection algorithms made more stringent from 5 beats at 150 beats/min to 11 beats at 200 beats/min to assess their effects on AMS efficacy. RESULTS Sensitivities:Mean SR-EGM = 3.55 mV; mean A-SENS = 2.06 mV; and mean AMS-SENS = 1.46 mV. Fourteen patients developed atrial fibrillation and four atrial flutter. Thirteen of 14 patients who developed atrial fibrillation sensed adequately at > or = 1.0 mV in normal sinus rhythm (NSR), but only six patients had effective AMS at these settings in atrial fibrillation. Three of four patients who developed atrial flutter had effective AMS at > or = 2.0 mV. AV Interval:AMS was effective in eight of ten patients at AV intervals up to 200 ms. One patient lost AMS at an AV interval of 120 ms. Algorithm: In two of seven patients, AMS was not effective if the detection algorithm was more stringent than five beats at 150 beats/min. CONCLUSIONS (1) In atrial fibrillation, effective AMS requires more sensitive atrial settings than in NSR; (2) AV intervals as short as 120 ms can interfere with AMS function; and (3) More stringent detection algorithms may be inappropriate for effective AMS function.

Background: The purpose of this trial was to evaluate a patient actuated transtelephonic cardiac monitoring system in order to document cardiac arrhythmias and cardiac pacemaker function. Material: Eighty-two patients were prospectively evaluated, 69 with pacemaker (group I) and 13 with symptomatic arrhythmias (group II). Two different recorders were used: a memory loop-recorder (KH) and a wrist-worn recorder (HW). Both of them were implemented using a small, portable, battery-powered transmitter, which monitors a modified V5 in KH and a lead 1 with the HW over regular nondigital pulse telephone lines. Results: In group I, 54 patients used single chamber pacemakers, 2 VDDR, and 13 used dual chamber devices. In group II, all patients included referred palpitations as their symptom. In group I, 248 registers were made using the KH and 50 with the HW. Recordings were made with KH had a 96% accuracy in the diagnosis of the ECG, while HW recordings failed to detect the QRS and the spike in 52% of the cases. Arrhythmia patients (group II) made 65 recordings with KH, all symptomatic: 28 were ventricular ectopic beats (23 isolated, 4 bigeminy, and 1 coupled ventricular ectopic beats); 9 supraventricular ectopic beats (isolated); 18 episodes of sinus tachycardia; and 10 normal sinus rhythm. Artifact was present partially in 6 other recordings, but did not affect the diagnosis. Two patients made no recordings and were excluded from the trial (group I). Conclusions: The loop-recording transtelephonic monitoring system is an excellent tool for the evaluation of patients with symptomatic arrhythmias and pacemaker. The memory KH had an excellent performance, even over regular telephone lines. The accuracy of the HW recordings was low and failed to evaluate the QRS, probably due to the direction of the AQRS vector.

We report the case of a patient with persistent cardiac rhythm originating from the superior vena cava (3 cm above the vena cava-atrial junction). It was detected by noncontact balloon mapping before induction of tachycardia and confirmed by conventional contact mapping with image studies. Thus, a 12-lead ECG showing normal morphologies of P waves may not indicate that the P waves are of sinus node origin.

OBJECTIVES To determine whether warm lavage liquid ventilation (LV) would provide rapid cardiopulmonary rewarming in swine with severe hypothermia and ventricular fibrillation. METHODS Intubated common swine (n = 3; mean +/- SEM weight 26+/-1.2 kg) were cooled to a mean aortic temperature of 26.4+/-0.9 degrees C. Ventricular fibrillation was induced by transthoracic electrical shock. Rewarming was initiated by continuous endotracheal instillation of warm (44 degrees C) pre-oxygenated, perfluorocarbon liquid at 5 mL/kg/min. Endotracheal instillation of perfluorocarbon occurred while standard gas ventilation continued. Manual chest compressions were performed throughout the 30-minute rewarming process. Outcome measures were the absolute and relative rates of change of all temperatures. RESULTS After 30 minutes of warm lavage LV, the mean aortic and pulmonary artery temperatures increased by 6.6+/-0.6 degrees C, respectively. Esophageal, nasal, and rectal temperatures did not change significantly. In one animal, normal sinus rhythm spontaneously returned after 16 minutes of rewarming. CONCLUSIONS During cardiac arrest, warm lavage liquid ventilation may produce rapid cardiopulmonary rewarming.

The pacing rate response of a new acceleration driven pulse generator (SWING 100, SORIN BIOMEDICA) was compared with simultaneous normal sinus rhythm (NSR) during two different treadmill exercises. This pacemaker has a gravitational acceleration sensor able to discriminate between physical activities and vibrations. Six healthy volunteers (three male, three female; aged 21.7 +/- 4.3 years), with the pacemaker strapped to their right infraclavicular area, performed each test three times with different rise response curve (RRC) each time: fast, normal, and slow. The fall response curve used was the same as the rising one during each test. Pacing rates were recorded using the VEGA analyzer (SORIN BIOMEDICA) and compared with simultaneous NSR recorded by a 7-channel ECG recorder (MINGOGRAF 7, SIEMENS). During all tests immediate (within seconds) rapid increase in pacemaker rate was seen up to about 60 seconds, then a slower increase followed thereafter. The mean correlation between pacing rates and NSR during the Bruce tests were 0.7941 +/- 0.10, 0.8562 +/- 0.14, and 0.8292 +/- 0.07; during the discontinuous tests 0.7292 +/- 0.16, 0.7233 +/- 0.10, and 0.7480 +/- 0.11 for fast, normal, and slow RRC, respectively. Each 30 seconds, nonsignificant differences were present between pacing rate and NSR during all the discontinuous tests; similar responses were observed only during the first two stages of Bruce tests after which NSR was significantly higher than pacemaker rates. The speed of rise to upper rate was the main difference between the different programs (fast, normal, and slow). The discontinuous tests showed that the pacemaker responds more to speed than to grade.(ABSTRACT TRUNCATED AT 250 WORDS)

The usual mode of controlling ventricular rate after His-bundle ablation is placement of a ventricular demand rate responsive pacemaker. Atrioventricular synchrony is therefore lost in individuals whose atrial rhythm disturbances are paroxysmal. Thirty-seven His ablations were performed at this institution, since January of 1983, for atrial rhythm disturbances that were not suppressible with medical therapy alone. Of those, ten patients were identified whose atrial rhythm disturbances were intermittent and who would otherwise benefit by having proper atrioventricular sequence during sinus rhythm. These patients underwent placement of a dual chamber pacemaker system having a fallback mode. At a mean follow-up period of 17 +/- 11 months, eight patients continued to maintain proper atrioventricular sequence with ventricular pacing tracking atrial activation during sinus rhythm. Supraventricular tachyarrhythmic attacks were associated with attainment of the programmed upper rate limit at which time the fallback mode was activated and the pacemaker automatically converted to a ventricular demand (VVI) mode. Restoration of normal sinus rhythm was associated with restoration of proper atrioventricular sequence. Two patients have developed chronic atrial fibrillation and their pacemakers continue to function in the fallback mode as VVI devices. In conclusion, intermittent supraventricular tachyarrhythmias which are resistant to drug therapy can be treated with His ablation and dual chamber pacing utilizing special pacemaker features such as the fallback mode.

WALSH, C.A., ET AL.: Differentiation of Sinus Rhythms from Supraventricular Tachydysrhythmias by Activation Sequence and Timing. Implantable device detection of tachydysrhythmias remains unreliable and inexact. False responses may occur because of misinterpretation of sinus tachycardia (ST) as a supraventricular tachydysrhythmia (SVTD). Timing of atrioventricular (AV) activation and ventricular dispersion identified and discriminated between ST and SVTDs in 11 dogs. Three bipolar epicardial electrodes recorded left atrial and left and right ventricular depolarizations simultaneously during normal sinus rhythm (NSRJ (mean of 5 beats in 11/11 dogs), ST produced by phlebotomy (50 beats in 10 episodes in 6/11) or isoproterenol infusion (105 beats in 21 episodes in 10/11), sinus bradycardia (SB) produced by vagal stimulation (140 beats in 29 episodes in 10/11), and during atrial flutter (AFL) (15 beats in 3 episodes in 3/11) and atrial fibrillation (AF) (152 beats in 31 episodes in 9/11) induced by programmed electrical stimulation. During lidocaine infusion, NSR (55 beats in 11 episodes in 10/11 dogs), SB (84 beats in 17 episodes in 7/11), AFL (10 beats in 2 episodes in 1/11], and AF (103 beats in 21 episodes in 7/11) were recorded. During isoproterenol infusion, SB (45 beats in 9 episodes in 5/11), AFL (15 beats in 3 episodes in 2/11), and AF (64 beats in 13 episodes in 5/11) were recorded in addition to ST. The interval between the left atrial and left ventricular intrinsic deflections (A-V1) and between the left and right ventricular intrinsic deflections (V1-V2) of each beat was measured. The mean value (msec) of A-V1 and V1-V2 in each episode was compared to NSR in the same dog. A difference of ≥ 16 ms was used for differentiation. In all cases except SB with first-degree AV block, V1-V2 in each episode was insignificant (0-14msec), categorizing the rhythms as supraventricular. During NSR, ST and SB without AV block, Δ A-V1 was small (0–15 msec). In contrast Δ A-V1 was ≥ 16 ms in 6/8 episodes of AFL. The remaining two episodes could be differentiated by the greater number of atrial versus ventricular beats. AF could be detected by the variability of A-V1. An algorithm using the relative number of atrial vs ventricular beats and A-V1 and V1-V2 timing can provide automated dysrhythmia detection, without effect from lidocaine or isoproterenol infusion.

Although prenatally detected intracardiac tumors are reported to have a poor prognosis, tumor regression and even tumor disappearance have been observed during childhood. A case of prenatal cessation of fetal cardiac tumor growth and return of cardiac arrhythmia to normal sinus rhythm is presented.

Background Although there are many well-known cardiac results of insecticide poisoning, atrial fibrillation (AF) has not been reported as the result of insecticide intoxication. Case Twenty-six-year-old male, complaining of nausea and vomiting, presented to the emergency department with a history of methomyl dust exposure. All physical examination findings were normal except irregular heart rate on cardiac auscultation. The electrocardiogram of the patient showed AF with normal ventricular response. Patient's acetylcholinesterase (ACE) level was 3,319 IU/L in presentation and pralidoxim use was seen unnecessary for the treatment. The patient's rhythm spontaneously returned to sinus rhythm 24 hr after the presentation and no cardiopulmonary pathology was found during the follow-up. The patient was discharged without symptoms. Conclusion AF is a rare complication of insecticide intoxication. In this case, treatment of symptoms was adequate until a normal sinus rhythm returned. Am. J. Ind. Med. 50:48–49, 2007. © 2006 Wiley-Liss, Inc.

Introduction: Currently the recommended treatment for atrial fibrillation is pharmacologic therapy. The ability of antiarrhythmic drugs to maintain normal sinus rhythm ranges from 39% to 79% in the first year. A multicenter, prospective clinical study involving 20 centers and 80 subjects has shown promising results for an effective, minimally invasive treatment of paroxysmal AF with a novel RF ablation microcatheter (Cardima®). Methods: Patients with drug refractory, paroxysmal AF were treated with an RF ablation version of the MAZE procedure placing linear lesions in the right atrium. Patients served as their own controls, establishing a baseline episode frequency in the 30 days prior to treatment. Treatment outcomes were compared to baseline to determine treatment effectiveness. Results: Of 79 subjects who reached 6 months follow up by July 2002, 46.8% reported 100% reduction in symptomatic AF episodes and 84.8% reported ≥50% reduction in episode frequency. Subjects also demonstrated clinically significant and statistically significant improvements in quality of life measurements. Conclusion: These results indicate substantial patient benefit from the minimally invasive maze procedure performed with the REVELATION Tx Microcatheter.

It has been argued that many subjects may have low awareness of visceral sensations because such feedback is of little relevance and salience in normal activity. This experiment examines awareness of cardiac sensations (heartbeats) in a group of 13 subjects, aged 37–67 yrs, all of whom had myocardial infarcts within the preceding 6 yrs previous to the experiment. Cardiac awareness was contrasted with the performance of a gender and age matched noncardiac control group on 80 Whitehead type discrimination trials. It was hypothesized that since rehabilitated cardiac patients frequently profess extreme sensitivity to their heart's activity and often experience benign arrhythmias which cause them to focus attention on their heart rate, that this group would show greater awareness of heartbeats than controls. The results clearly show that cardiac patients are no better able to discriminate true from false trials than are normals. Only one of 26 subjects showed above chance levels of discrimination, which is much lower than the percentage usually reported for young adult subjects. Respiration rate and amplitude, finger pulse volume, and heart period showed no differences between groups. The results suggest that although cardiac patients may feel aware of cardiac activity, they show no higher awareness of heartbeats during normal sinus rhythm than noncardiac controls.

Three young Standardbred pacers with atrial fibrillation were treated with quinidine sulphate (QS) by stomach tube. They were given 10g QS every 2 hours until cardioversion was achieved. Total doses varied between 20 and 30 g. No premedication was given nor any follow up treatment after return to sinus rhythm. All horses were given 3 months rest after the treatment, and when electrocardiographed then, and at 6 months, showed normal sinus rhythm. As all 3 horses won races after cardioversion and showed subsequent normal electrocardiograms it seems likely that atrial fibrillation can occur without detectable pathological changes in the heart.

LIN, D., ET AL.: Identification of ventricular tachycardia using intracavitary ventricular electrograms: analysis of time and frequency domain patterns. Tachycardia detection by impladtable antitachycardia devices using rate alone has major limitations. Several alternative methods have bden proposed to distinguish ventricular tachycardia or ventricular fibrillation from normal sinus rhythm using intracardiac electrograms. These methods have not been tested, however, for recognition ofventticular tachycardia in patients with abnormal surface QRS conduction during sinus rhythm or with antiarrhythrnic drug therapy. In this study, three techniques for the indentification of ventricular tachycardia from intracavitary bipolar ventricular electrograms were examined and compared: correlation waveform analpsis, amplitude distribution analysis, and spectral analysis using Fast Fourier transformation. Thirty episodes of induced monomorphic ventricular tachycardia were analyzed and compared sinus rhythm in four groups of patients with: 1. Normal surface QRS conduction during sinus rhythm without antidrrhythmic drug therapy [five episodes); 11. Intraventricular conduction delay or bundle branch block during sinus rhythm without antiarrhythmic drug therapy [nine episodes); III. Normal surface QRS conduction during sinus rhythm with antiarrhythmic therapy (six episodes); and N. Intraventricular conduotion delay or bundle branch block during sinus rhythm with antiarrhythmic drug therapy (ten episodes). Correlation waveform analysis had 100% sensitivity and specificity in distinguishing ventricular tachycardia from sinus rhythm, even in the presence of an intraventricular conduction delay, bundle branch block, and antiarrhythmic drug therapy. In contrast, amplitude distribution analysis differentiated 15/30 episodes (50.0%) ofventricular tachycardia from sinus rhythm, and a maximum of 18/30 episodes (60.0%) of ventricular tachycardia were identified by specal analysis using Fast Fourier transformation. Correlation waveform analysis appears to be a reliable technique to discriminate ventricular tachycardia from sinus rhythm using intracavitary ventricular electrograms. Its computational demands are modest, making it suitable for consideration in an implantable antitachycardia device. [PACE, Vol. 11, November 1988)

The use of two ventricular sensing electrodes to determine electrical activation sequence could provide a method for differentiation of normal from abnormal rhythms by implantable antitachycardia devices. Simultaneous recordings from two ventricular sites were obtained during dual chamber pacemaker implantation (5/8 patients), cardioverter-defibrillator implantation (2/8 patients), or programmed electrical stimulation study (1/8 patients). Recordings were made in normal sinus rhythm (NSR) (5 beats each in 8/8 patients), during ventricular tachycardia (VT) (38 beats with 7 morphologies in 3 patients) and during premature ventricular contractions (PVCs) (20 beats with 8 morphologies in 6 patients). Leads were placed transvenously in the right ventricle in 6 patients, and epicardially on the left ventricle in two. Intervals between the intrinsic deflection of the two ventricular electrograms ranged from 0 to 91 ms (mean of 26 ms) during NSR, from 13 to 141 ms (mean of 66 ms) during VT, and from 10 to 72 ms (mean of 40 ms) during PVCs and were reproducible within each patient for each type of rhythm. In all patients, the difference in sequence and timing between the dual electrograms in NSR beats vs. ectopic beats allowed for the differentiation of normal and abnormal complexes. These differences in each patient ranged from 23 to 210 ms (mean of 81 ms) during VT and from 3 to 89 ms (mean of 44 ms) during PVCs. Fourteen of the 15 ectopic morphologies exhibited greater than 20 ms difference in timing compared to their corresponding NSR beats. Combined with the appropriate software, multiple ventricular leads may be used by antitachycardia devices to discriminate between normal and abnormal ventricular activity.

A patient with symptomatic sick sinus syndrome which manifested as a brady-tachy syndrome, was admitted to our institute in 1969. Following cardiac pacing for 10.5 years, the brady-tachy syndrome disappeared and normal sinus rhythm was restored. Her stable normal sinus rate has persisted up to the present, 2.5 years after termination of pacing.

Isolated tricuspid insufficiency (TI) is relatively uncommon and mostly of traumatic origin. We report clinical noninvasive and invasive findings and surgical results in 5 cases. All patients had complete clinical, noninvasive and invasive studies including right and left catheterization, and coronary angiographies in 3 patients. All but 1 patient had nonpenetrating trauma. All had large jugular V waves, right precordial impulse, systolic liver pulse, positive Carvallo sign documented also by noninvasive techniques. Right heart failure was present in 3 patients. Chest x-ray showed prominent right atrium and distended vena cavae. Electrocardiogram showed normal sinus rhythm in 4 patients and atrial fibrillation in 1. Two patients had right bundle-branch block, and 2 presented RSR'-pattern. Echocardiogram showed large right atrium (RA) (6-10 cm), floppy tricuspid valve (TV) in all, dilated right ventricle (RV) in 2 patients. Findings of left heart were normal in all. Three patients had right-to-left shunt. In RA A waves were 4-8, Y waves 1-3, and V waves 12-22 mmHg, respectively (mean RV and PA pressures were 23/3 and 23/10 mmHg, respectively). Four patients had anuloplasty, 2 of them repair of valve and chordae. Surgical results were good in 2 patients with valve repair, satisfactory in 1; there was significant TI resistance in 1 case. We conclude that TI has distinctive clinical findings and must be ruled out in all patients with chest trauma. Surgery must include not only anuloplasty, but, cusps and chordae must also be evaluated and reconstructed if necessary.

Two patients with hemodynamically well-tolerated recurrent ventricular tachycardia, drug resistani and previousiy requiring numerous external electrical cardioversions, had a permanent pacemaker implanted which could be programmed lo deliver extrastimuli to convert the ventricular tachycardia to normal sinus rhythm. The patient- or physician-activated device can be programmed to induce or terminate ventricular tachycardia with extrastimuli delivered at the predetermined intervals which consistently induced or terminated the arrhythmia in the electrophysiology laboratory, allowing repeated evaluation of drug regimens. The pacemaker has reliably, painlessly, and consistently induced and terminated repeated episodes of ventricular tachycardia. This programmable pacemaker offers an alternative therapy for patients with hemodynamically weil-tolerated refractory ventricular tachycardia. (PACE. Vol. 5, May-June, 1982)

Nursing home patients were studied to determine the usefulness of a maintenance dose of digoxin in elderly patients with normal sinus rhythm. Of 64 patients, 26 were identified to be on digoxin. Thorough history and physical examination were done on all the patients. Baseline electrocardiogram showed normal sinus rhythm in 19 patients, who were observed very closely for the period of four months after withdrawal of digoxin. Eighteen of 19 patients did well without digoxin, which suggests that most of the elderly nursing home patients with normal sinus rhythm do not need a maintenance dose of digoxin. J Am Geriatr Soc 33:850, 1985

A rare side effect is reported following treatment of preterm labor with ritodrine hydrochloride. The patient developed persistent supraventricular tachycardia, which had to be changed to normal sinus rhythm by cardioconversion.