Paroxysmal Atrial Arrhythmias Research Articles

Prevalence and Associated Factors of Paroxysmal Atrial Fibrillation and Atrial Arrhythmias During Hospitalizations for Exacerbation of COPD.

This study aimed to investigate the proportion and risk factors of paroxysmal atrial fibrillation (AF) and atrial arrhythmias (AA) in patients hospitalized for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in Vietnam. A prospective observational study was conducted at two major hospitals in Hanoi, Vietnam, from January 2022 to January 2023. A total of 197 AECOPD patients were recruited. ECG and 24-hour Holter ECG were used to diagnose paroxysmal AF and AA. The prevalence of paroxysmal AF and AA were 15.2% and 72.6%, respectively. Factors associated with a higher likelihood of paroxysmal AF included aging 75 years old and above (aOR = 3.15; 95% CI: 1.28 to 8.48), Premature atrial complex (PAC) with 500 or more (aOR = 3.81; 95% CI: 1.48 to 10.97) and severity of COPD as group C and D (aOR = 3.41; 95% CI: 1.28 to 10.50). For AA, aging 75 years old and above (aOR = 2.25; 95% CI: 1.28 to 5.20), smoking (aOR = 2.10; 95% CI: 1.07 to 4.23) and P wave dispersion (PWD) with 40 milliseconds or more (aOR = 3.04; 95% CI: 1.54 to 6.19) were associated with a higher likelihood of AA. Overall, our findings highlight the associated factors with the paroxysmal AF and AA among AECOPD patients. This underscores the importance of a multifaceted approach to risk assessment and management in this vulnerable population, focusing not only on respiratory symptoms but also on comprehensive cardiovascular evaluation and intervention.

PO-702-06 SUCCESSFUL TREATMENT OF SWALLOWING INDUCED ATRIAL TACHYCARDIA WITH SCOPOLAMINE

Swallowing Induced Atrial Tachycardia (SIAT) is a rare clinical entity with an incidence of 0.6% among paroxysmal atrial arrhythmias. It is usually seen in middle aged males and is associated with structurally normal hearts. The tachycardia originally thought to be related to a mechanical effect of the esophagus on the left atrium was shown under ICE to initiate with swallowing but before peristalsis. Recent data from heart rate variability analyses also indicate a surge in parasympathetic activity prior to induction of tachycardia.

Changes in Renal Function in Patients with Recurrence of Atrial Arrhythmia after an Initial Catheter Ablation.

Background Impaired renal function and atrial fibrillation (AF) can form a vicious cycle. Although there have been reports on improved renal function in patients who undergo successful AF ablation, renal function in patients with recurrence of AF has not been studied separately. We explored the changes in renal function in recurrent AF patients after catheter ablation with mild renal dysfunction and the influencing factors. Methods We retrospectively recruited nonvalvular AF (NVAF) patients with mildly impaired renal function admitted for catheter ablation and readmitted due to recurrence of AF. The estimated glomerular filtration rate (eGFR) was calculated before the index procedure and during readmission. △eGFR was defined as the difference between eGFR readmission and eGFR baseline. The same calculation applied for △CHA2DS2-VASc score. The primary endpoint was improved renal function (△eGFR >0) after AF catheter ablation in patients with atrial arrhythmia recurrence. Results A total of 132 NVAF patients were included in this study. The mean eGFR at readmission was significantly increased compared with the eGFR at baseline before the index ablation procedure (81.5 ± 1.1 vs. 78.0 ± 0.7 ml/min/1.73 m2, P < 0.001). The multivariable Cox regression analysis showed that a lower △CHA2DS2-VASc score (HR: 0.42, P=0.003) and paroxysmal recurrent atrial arrhythmia (HR: 2.97, P=0.001) were associated with better renal function. Conclusion In NVAF patients with mildly impaired renal function, even those with recurrence after the initial catheter ablation, we observed improvements in renal function, which was associated with a lower △CHA2DS2-VASc score and paroxysmal recurrent arrhythmia.

Bilateral coronary-pulmonary artery fistula with paroxysmal atrial arrhythmia: a case report

Bilateral coronary-pulmonary artery fistula with paroxysmal atrial arrhythmia: a case report

298Atrioventricular synchronous pacing in leadless ventricular pacemaker is safe and effective in patients with paroxysmal AV block and atrial arrhythmias

Abstract Funding Acknowledgements Medtronic, Inc. Background/Introduction Accelerometer (ACC)-based AV synchronous pacing by tracking atrial activity is feasible using a leadless ventricular pacemaker. Patients may experience variable AV conduction (AVC) and/or atrial arrhythmias during the lifetime of their device. ACC-based AV synchronous pacing should facilitate AVC and pace appropriately in those two common rhythms. Purpose To characterize the behavior of ACC-based AV synchronous pacing algorithms during paroxysmal AV block (AVB) and atrial arrhythmias. Methods The MARVEL2 (Micra Atrial tRacking using a Ventricular accELerometer) was a 5-hour acute study to assess the efficacy of atrial tracking with a temporarily downloaded algorithm into a Micra leadless pacemaker. Patients with a history of AVB were eligible for inclusion. The MARVEL2 algorithm included a mode-switching algorithm that switched between VDD and VVI-40 depending upon AVC status. The AVC algorithm requires 2 ventricular paces (VP) at 40 bpm out of 4 pacing cycles to switch to VDD. Results Overall, 75 patients (age 77.5 ± 11.8 years, 40% female, median time from Micra implant 9.7 months) from 12 centers worldwide were enrolled. During study procedures, 40 patients (53%) had normal sinus rhythm with complete AVB, 18 (24%) had 1:1 AVC, 5 (7%) had varying AVC status, 8 (11%) had atrial arrhythmias, and 2 other rhythms. Two patients with complete AVB had the AVC mode switch feature disabled due to an idioventricular rate &amp;gt;40 bpm. Among the 40 subjects with a predominant 3rd degree AVB and normal sinus function the median %VP was 99.9% compared to 0.2% among those with 1:1 AVC (Figure). In the patients with 1:1 AVC, there were 64 opportunities to AVC mode switch with 48 switching to VDI-40. In the other 16 cases (2 patients) the mode remained VDD due to sinus bradycardia varying between 40-45 bpm. High %VP was observed in 2 patients with 1:1 AVC and sinus bradycardia &amp;lt;40 bpm. The AVC mode switch minimized %VP (&amp;lt;1%) in patients with PR intervals &amp;gt; 300 ms (N = 2). Among patients with varying AVC, the algorithm appropriately switched to VDD when the ventricular rate was paced at 40 bpm. During infrequent AVB or AF with ventricular response &amp;gt;40 bpm, VVI-40 mode was maintained. In patients with AF, the ACC signal was of low amplitude and there was infrequent sensing, resulting in VP at the lower rate (50 bpm). In the one patient with atrial flutter, the ACC was intermittently detected, resulting in VP at 67 bpm (IQR 66-67 bpm). Conclusion(s) The mode switching algorithm in the MARVEL2 reduced %VP in patients with 1:1 AVC and appropriately switched to VDD during complete AVB. If greater AV synchrony or rate support is required, disabling the AVC algorithm may be appropriate for low grade AVB or idioventricular rhythms. In the presence of atrial arrhythmias, the algorithm paced near the lower rate. Abstract Figure. Distribution of VP% by heart rhythm

Atrial arrhythmia after transcatheter closure of secundum atrial septal defects in patients ≥40 years of age.

Data on arrhythmia outcome following device closure of atrial septal defect (ASD) are lacking. This study provides medium-term follow-up data on atrial arrhythmias in patients who were ≥40 years of age at the time of transcatheter ASD closure. It is a retrospective review. Mean age of the 159 patients was 57 years. Median follow-up was 3.6 years (range 6 months-10.9 years). Patients were classified, according to arrhythmia status prior to ASD closure, into Group I, no history of atrial arrhythmia (n = 119, mean age 55.5 years); Group II, paroxysmal atrial arrhythmia (n = 18, mean age 55.7 years); and Group III, persistent atrial fibrillation (n = 22, mean age 65.7 years). Group III patients were significantly older, had larger left atrial size, and had higher mean pulmonary arterial pressure than Group I and II patients (P < 0.001). Prior to closure, radiofrequency ablation was carried out in 12/18 (66%) of Group II and 3/22 (14%) of Group III. After device closure, 7 patients (6%) of Group I developed new atrial fibrillation. Fifty per cent (9/18) of Group II but only 9% (2/22) of Group III were in sinus rhythm on follow-up. Device closure alone in patients with persistent atrial arrhythmia is not likely to restore sinus rhythm in the medium term. New atrial arrhythmia occurred in 6% of patients who were in sinus rhythm prior to device closure. At least 50% of the patients with paroxysmal atrial arrhythmia continue to have significant atrial arrhythmia following device closure, and the role of ablation prior to closure in patients with a history of arrhythmia requires refinement.

Multidisciplinary Assessment in Optimising Results of Percutaneous Patent Foramen Ovale Closure.

Percutaneous patent foramen ovale (PFO) closure is a therapeutic option to prevent recurrent cerebral ischaemia in patients with cryptogenic stroke and transient cerebral ischaemia (TIA). The apparent lack of benefit seen in previous randomised trials has, in part, reflected inclusion of patients with alternate mechanisms of stroke. The role of formal neurology involvement in accurately delineating the likely aetiology of stroke or TIA is crucial in appropriate identification of patients for device closure. Furthermore, as the benefits of device closure may accrue over time, long-term follow-up is essential to define the role of device closure in management of presumed cryptogenic stroke. We retrospectively reviewed our experience with percutaneous PFO device closure since 2005. All subjects who underwent PFO closure at John Hunter and Lake Macquarie Private Hospitals were included in the study. All patients referred for device closure following cryptogenic stroke or TIA had first undergone formal neurology review with appropriate imaging and exclusion of paroxysmal atrial arrhythmia. Patients with a history of transient ischaemic attack (TIA) are frequently referred to a specialised clinic, aimed to identify patients with conditions not referable to cerebral ischaemia, with investigations initiated by the specialist clinic to elucidate an underlying aetiology. Outcome data was derived from the Hunter New England Area Local Health District Cardiac and Stroke Outcomes Unit, in addition to review of the medical record. The Cardiac and Stroke Outcomes Unit prospectively identified all patients presenting with stroke, TIA and atrial fibrillation. One hundred and twelve consecutive patients undergoing percutaneous patent foramen ovale closure between 2005 and 2015 were identified. The average age was 42.7 years and 57 (50.9%) patients were male. Cryptogenic stroke (68.8%) and transient cerebral ischaemia (23.2%) were the most common indications for PFO closure, with the Amplatzer device used in 83 cases (74.1%). Early residual shunting was visible in seven patients (6.3%), however on follow-up agitated saline study only two patients had residual shunt (1.8%). The annual risk of recurrent stroke or TIA was 0.21%. Percutaneous patent foramen ovale closure can be performed safely and effectively in patients with paradoxical embolism. In selected patients, following appropriate multidisciplinary specialist pre-procedural assessment, excellent long-term results with low incidence of recurrent events may be achieved.

96-15: Atrial tachyarrhythmias in patients after surgical CryoMaze ablation procedure

Purpose of the study: The CryoMaze ablation procedure was developed as a surgical alternative to incisional treatment for atrial fibrillation. Incomplete lines can decrease the efficacy of the ablation procedure and can be proarrhythmic. The aim of this study is to determine incidence and mechanisms of atrial tachyarrhythmias occurring after surgical CryoMaze. We also studied the efficacy of completing surgical lines by RF catheter ablation to maintain sinus rhythm. Methods: Fourty-eight consecutive patients who required surgical CryoMaze ablation for persistent atrial fibrillation as an adjunct to a cardiac surgery were enrolled in the study. All patients had a 7-day ECG Holter 3 months after the surgical CryoMaze. Patients with documented paroxysmal or persistent atrial arrhythmias on the ECG Holter underwent an electrophysiological study with the right and left atria electroanatomical mapping using a CARTO3 navigation system. According to the protocol, patients in sinus rhythm were tested with incremental atrial pacing to induce atrial tachyarrhythmias after all gaps in surgical lines had been re-ablated using RF catheter ablation. If persistent atrial tachycardia was recorded at the beginning of the study, the tachycardia was mapped and ablated as the first step, which was followed by finalization of the surgical lines. All patients were followed-up for 24 months with repeated 7-day ECG Holters Summary of results: Thirteen (27%) patients had persistent and 12 (25%) patients had paroxysmal atrial tachyarrhythmia on the 7-day ECG Holter. Persistent arrhythmias were later confirmed during the electrophysiological study as atrial fibrillation in 5 patients, typical isthmus-dependent atrial flutter in 4 patients, 2 peri-mitral flutters, 1 roof dependent flutter and 1 focal atrial tachycardia from the inter-atrial septum. In patients with sinus rhythm in the beginning of the study, surgical lines were re-ablated in all patients. In 3 cases, incremental atrial pacing induced different focal atrial tachycardias after all surgical ablation lines had been finalized. All spontaneous and inducible arrhythmias were successfully mapped and ablated. Twenty-three out of 25 patients who underwent catheter ablation after surgical CryoMaze remained in sinus rhythm without antiarrhythmic medication during the 24-month follow-up. Conclusion: One quarter of patients after surgical CryoMaze suffer from persistent atrial tachyarrhythmias and another quarter have paroxysmal atrial arrhythmias. Catheter ablation of these tachyarrhythmias and finalization of surgical lines is effective approach to treat patients with documented atrial arrhythmias after surgical CryoMaze.

62 Prolonged, Intermittent Monitoring using a Handheld ECG Significantly Increases the Diagnostic Yield of Paroxysmal Atrial Fibrillation

Purpose Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia. Paroxysmal AF (PAF) comprises approximately half of AF cases and poses an equivalent risk of thromboembolism to other AF sub-types. However, PAF poses a particular diagnostic challenge given its variable frequency, potential brevity and frequent lack of symptoms. Currently, no definitive method to identify PAF has been proposed although 24-hour or 1-week rhythm monitoring remain common practice. We aim to determine whether the longer-term, intermittent use of a handheld ECG monitor is an effective investigational tool to improve the diagnosis of PAF in a targeted population. Methods Patients meeting the following criteria were entered into the study: suspected paroxysmal atrial arrhythmia (defined as palpitations or detection of an irregular pulse); aged 40 years and over; no previously documented atrial arrhythmia; sinus rhythm confirmed with a 12-lead ECG; no significant electrolyte disturbance. Participants were issued with an automated cardiac event recorder for 1-week, deemed standard practice (R Test Evolution 4, Novacor). They also used a handheld ECG monitor (OMRON Portable ECG Monitor HCG-801), recording 30-second segments twice-daily and with relevant symptoms, for a 12-week period. Recordings were analysed by a blinded cardiologist. Results We recruited 110 consecutive eligible participants (mean age 66 years; 70% female). 84% were referred with palpitations and 16% with an irregular pulse. 90% of participants completed the study and 99% of recordings were suitable for analysis. Atrial arrhythmias were detected in 29 patients (26%). Of these 23 were diagnosed with PAF, 5 with atrial flutter and 1 with atrial tachycardia. This group had a mean CHA 2 DS 2 VASc score of 2.1. 31% of cases were identified using the standard device, 41% using the handheld ECG monitor (p = 0.72) and 28% with both devices. A significantly greater number of atrial arrhythmias were detected over a 12-week monitoring period as compared to both a 24-hour (n = 29 vs 5, p = 0.0001) and 1-week monitoring period (n = 29 vs 17, p = 0.03); see Figure 1. Conclusions The intermittent use of a handheld ECG monitor over 12-weeks significantly increases the diagnostic yield of PAF when compared to standard investigation. Our findings suggest that the duration of cardiac monitoring used in current practice should be extended.

Complex atrial arrhythmias as first manifestation of catecholaminergic polymorphic ventricular tachycardia: an unusual course in a patient with a new mutation in ryanodine receptor type 2 gene

Catecholaminergic polymorphic ventricular tachycardia is a rare life-threatening arrhythmogenic disorder. An association with paroxysmal atrial fibrillation and other atrial arrhythmias has been described, but in all published cases the initial manifestation of the disease was ventricular arrhythmia. This is the first report about a patient who presented with complex atrial tachycardia and sinus node dysfunction about 1 year before the typical ventricular arrhythmias were observed, leading to the diagnosis of catecholaminergic polymorphic ventricular tachycardia. In this girl, a mutation of the ryanodine receptor type 2 gene, which has not been described so far, was discovered.

Atrial arrhythmia after Fontan surgery leads to giant thrombus: Opening Pandora's box

The Fontan procedure is performed in paediatric patients with a single anatomical or functional ventricle aiming to redirect the venous blood flow directly to the lungs bypassing the single ventricle [1]. The most common form of Fontan surgery is the atriopulmonary connection in which the right atrium is connected to the pulmonary artery. In this case, the right atrium functions at higher than normal pressures leading to atrial distension and injury to the sinus node or its blood supply [2]. Late consequence of the above is the occurrence of paroxysmal or persistent atrial arrhythmias [3].

Cardiac Arrhythmias in Obstructive Sleep Apnea (from the Akershus Sleep Apnea Project)

Increased prevalence of cardiac arrhythmias has been reported in patients with severe obstructive sleep apnea (OSA), but this may not be generalizable to patients from the general population with a milder form of the condition. The aim of this study was to assess the association between cardiac arrhythmias and OSA of mainly mild and moderate severity. In total, 486 subjects (mean age 49 years, 55% men) recruited from a population-based study in Norway underwent polysomnography for OSA assessment and Holter recordings for arrhythmia assessment. Of these, 271 patients were diagnosed with OSA (apnea-hypopnea index [AHI] ≥5, median AHI 16.8, quartiles 1 to 3 8.9 to 32.6). Mean nadir oxygen saturations were 82% and 89% in patients with and without OSA, respectively. Ventricular premature complexes (≥5/hour) were more prevalent in subjects with OSA compared to subjects without OSA (median AHI 1.4, quartiles 1 to 3 0.5 to 3.0) during the night (12.2% vs 4.7%, p = 0.005) and day (14% vs 5.1%, p = 0.002). In multivariate analysis after adjusting for relevant confounders, AHI was independently associated with an increased prevalence of ventricular premature complexes at night (odds ratio per 1-U increase of log-transformed AHI 1.5, 95% confidence interval 1.1 to 2.0, p = 0.008) and during the day (odds ratio 1.37, 95% confidence interval 1.0 to 1.8, p = 0.035). In conclusion, the prevalence of ventricular premature complexes is increased in middle-aged patients with mainly mild or moderate OSA, suggesting an association between OSA and ventricular arrhythmias even in mild OSA.

Does Bachmann's bundle pacing prevent atrial fibrillation in myotonic dystrophy type 1 patients? A 12 months follow-up study

Paroxysmal atrial arrhythmias occur in myotonic dystrophy type 1 (MD1) patients frequently. Pacemaker (PM) including detailed diagnostic functions may facilitate the diagnosis and management of frequent paroxysmal atrial tachyarrhythmias that may remain undetected during conventional clinical follow-up. Aim of our study was to evaluate the preventive effects of interatrial septum pacing in the Bachmann's Bundle region on atrial fibrillation (AF) in MD1 patients during 12 months follow up period. Thirty MD1 patients (age 50.3 +/- 7.3; 11 F) who underwent dual chamber PM implantation were randomized at implantation to receive right atrial appendage pacing (16 patients) or Bachmann's bundle pacing (14 patients). No statistically significant difference in the electrical parameters (P wave amplitude, pacing threshold and lead impedance) was found between the two groups at implantation. Patients were followed at 1 month, 3 months, and every 6 months thereafter. They underwent clinical assessment, a standard 12-lead ECG and assessment of device performance at every visit. We counted the number of episodes of atrial arrhythmia occurred during the collection period and the duration of each episode. At 12 months of follow-up, no statistically significant differences in the number of AF episodes or in AF duration were found. Lead parameters remained stable over time and there were no displacements of the electrodes after implantation. Implantation of an atrial-active fixation lead on the atrial septum is safe and feasible. However, this study showed no significant difference between septal pacing and high atrial pacing, using the endpoints of AF duration and number of AF episodes.

What have we learned about the contribution of autonomic nervous system to human arrhythmia?

Myocardial infarction results in denervation, followed by neural remodeling characterized by nerve sprouting and heterogeneous sympathetic hyperinnervation throughout the myocardium. There is an association between the density of sympathetic nerves and occurrence of cardiac arrhythmia in humans. Autonomic nerve recording in ambulatory dogs showed a close association between autonomic nerve activity and paroxysmal atrial and ventricular arrhythmias. Cryoablation of the stellate ganglion prevented paroxysmal atrial tachycardia and atrial fibrillation in canine models. Further studies are needed to determine if these same methods can be used to control atrial arrhythmias in humans.

An unusual diagnosis of atrial shunt defect by magnetic resonance imaging

Paroxysmal atrial arrhythmias especially atrial fibrillation are frequently encountered in adult patients with atrial septal defect. However, the diagnosis of atrial defect can be difficult. Thransthoracic echocardiography, the mostly utilized cardiac technique, has shown a limited ability to identify small atrial defects. Transesophageal echocardiography has shown high accuracy to identify but it isn't well tolerated of the patients. Recently, the utility of multislice computed tomography in the evaluation of direction, location, and size of shunt flow in congenital heart disease has been demonstrated. Cardiac magnetic resonance imaging (MRI) is a recent imaging technique that permits with high spatial resolution and without ionising radiation an accurate identification of many cardiovascular diseases. We report an unusual detection of an atrial defect by phase-contrast cine MRI in a patient clinically suspected of arrhitmogenic right ventricular displasia.

A Case of Acute Ventricular Capture Threshold Rise Associated with Flecainide Acetate

Antiarrhythmic agents may increase capture threshold, but this is rarely of clinical significance. Flecainide acetate, a class IC agent, is reported to have a significant effect on the myocardial capture threshold. In this presentation, we report the case of a 72-year-old male, with a previously implanted VVI pacemaker due to sick sinus syndrome, who was treated with flecainide acetate for paroxysmal atrial arrhythmia control. During the fifteenth day of treatment, an abrupt rise in the ventricular capture threshold with ventricular pacing failure was noted. The capture threshold decreased two days after discontinuation of flecainide acetate.

24-hour ambulatory electrocardiographic monitoring is unhelpful in the investigation of older persons with recurrent falls

Although frequently used in the assessment of patients with falls, it is unclear whether 24-hour ambulatory electrocardiography contributes to their assessment in older persons. To identify electrocardiographic abnormalities in patients with recurrent falls and case controls, and determine whether 24-hour ambulatory electrocardiography identifies causal arrhythmias for falls. Prospective case-control study. 24-hour ambulatory electrocardiography recordings were compared for the type and prevalence of arrhythmias and symptom correlation in consecutive older subjects with recurrent falls attending the accident and emergency department and in case controls (no previous falls or syncope). ECG abnormalities were categorised as major (ventricular arrhythmia, pauses, <30 b.p.m., Mobitz II, complete heart block) and minor (multiple ectopics, paroxysmal atrial arrhythmia and other bradyarrhythmias). 128 fallers (76 +/-6 years) and 100 case controls (75 +/-5 years) were recruited. Co-medication and co-morbidity were similar in both groups. 49% (63) of recordings in fallers and 41% (41) of recordings in controls were abnormal. There was no difference between groups in the prevalence of major or minor abnormalities or of symptoms during recording (breathlessness, fatigue, chest pain and dizziness). Palpitations occurred in 10% of fallers and 13% of controls. One patient fell during monitoring with no associated rhythm abnormality. Multiple abnormalities are present on 24-hour ambulatory electrocardiography in older people whether or not they have experienced falls. 24-hour electrocardiography does not discriminate between fallers and non-fallers and is not helpful in the investigation of recurrent falls.

Evaluation of P wave duration and P wave dispersion in adult patients with secundum atrial septal defect during normal sinus rhythm

Background: Paroxysmal atrial arrhythmias especially atrial fibrillation (AF) are frequently encountered in adult patients with atrial septal defect (ASD). Previously it was shown that maximum P wave duration and P wave dispersion in 12-lead surface electrocardiograms are significantly increased in individuals with a history of paroxysmal AF. The aim of this study was to determine whether P maximum and P dispersion in adult patients with ASD and without AF are increased as compared to healthy controls. In addition, the relationship of pulmonary to systemic flow ratio ( Qp/ Qs) and these P wave indices were investigated. Methods and results: Sixty-two consecutive patients [39 women, 23 men; mean age 33±13 years (range 16 to 61 years)] with ostium secundum type ASD and 47 healthy subjects [25 women, 22 men; mean age 36.6±9.5 years (range 18 to 50 years)] were investigated. P maximum, P minimum and P dispersion (maximum minus minimum P wave duration) were measured from the 12-lead surface ECG. There were no significant differences with respect to age ( P=0.08), gender ( P=0.3), heart rate ( P=0.3), left atrial diameter ( P=0.5) and left ventricular ejection fraction ( P=0.3) between patients and controls. Pulmonary artery peak systolic pressure was significantly higher in patients with ASD as compared to controls ( P<0.0001). P maximum was significantly longer in patients with ASD as compared to controls ( P<0.0001). In addition, P dispersion of the patients was significantly higher than controls ( P=0.001). P minimum was not different between groups ( P=0.12). Mean Qp/ Qs of the patients with ASD was 2.5±0.7 (minimum 1.5; maximum 4.1) and found to be significantly correlated with P maximum ( r=0.34; P=0.006) and P dispersion ( r=0.61; P<0.0001). Conclusions: Prolongation of P maximum and increased P dispersion could represent mechanical and electrical changes of atrial myocardium in patients with ASD. These changes of atrial myocardium may be more prominent with higher left to right shunt volumes.

Significant association of atrial vulnerability with atrial septal abnormalities in young patients with ischemic stroke of unknown cause.

Atrial septal abnormalities have been associated with cryptogenic ischemic stroke in young patients, but the causal link has not yet been established. Paradoxical embolism is considered the most likely mechanism but is rarely proven. It can be hypothesized that, in those patients, paroxysmal atrial arrhythmias, potentially favored by the anatomic abnormalities, can be another cause of thrombus formation and subsequent embolism to the brain. In this study we assessed the relationship between atrial vulnerability, reflecting arrhythmogenic properties of the atria, and atrial septal abnormalities in young patients with cryptogenic ischemic stroke. We enrolled 62 consecutive patients aged <55 years who had ischemic stroke of unknown cause and transesophageal echocardiography to assess atrial septal aneurysm (ASA) or patent foramen ovale (PFO) (ie, atrial septal abnormalities). These patients underwent electrophysiological study to measure atrial refractoriness and conduction time defining a vulnerability index (ie, latent atrial vulnerability) and to assess the inducibility of sustained (lasting >60 seconds) atrial fibrillation with the use of programmed atrial stimulation. Actual atrial vulnerability was defined by the presence of both latent vulnerability and inducibility of sustained atrial fibrillation lasting >60 seconds. We found atrial vulnerability in 58% of patients with atrial septal abnormalities and in 25% of patients without (odds ratio=4.1 [95% CI, 1.3 to 12.7; P<0.02]). The difference between patients with and without PFO or between patients with both PFO and ASA and those without were also significant. Patients with inducible sustained atrial fibrillation had more frequent past history of palpitations and syncope than patients without (P<0.02). Atrial vulnerability is associated with atrial septal abnormalities in patients with cryptogenic stroke. This result raises the question of the potential role of transient atrial arrhythmias in thrombus formation in the presence of PFO or ASA.

Tiered management of atrial arrhythmias: The Pulsar Max TM family of pacemakers

Background: In order to provide atrioventricular (AV) synchronous pacing in patients with paroxysmal atrial arrhythmias, a number of automatic mode switching algorithms have been developed since the early 1990s. Aim and method: One aim of mode switching is to achieve an appropriate ventricular rate during atrial arrhythmias by using smooth transitions between atrial tracking and nontracking modes. The new family of Pulsar MaxTM pacemakers (Guidant, St Paul, MN) has a two-zone mode switching algorithm, consisting of atrial tachy response (ATR) and atrial flutter response (AFR). Results: This two-zone approach enables discrimination between atrial tachycardia and atrial flutter, helping to minimize patient symptoms. Related parameters, such as atrial sensitivity and blanking periods, must also be appropriately programmed to optimize mode switch function. Suggestions are given for programming these related parameters, as well as for ATR/AFR. Pulsar MaxTM pacemakers also provide advanced diagnostics to enable verification of appropriateness of mode switching. They have the capability of storing intracardiac electrograms during mode switching episodes. Several examples are given to illustrate how the device facilitates assessment of appropriate versus inappropriate mode switching. Conclusion: Use of these pacemaker features may help physicians otimize pacing therapy for their patients. The ultimate goal is to help prevent uncomfortable symptoms in pacemaker patients prone to atrial tachyarrhythmias.