Atrial Dissociation Research Articles

Results of Palliative Stenting in Malignant Superior Vena Cava Syndrome Analyzing Self-Expanding Stainless Steel and Nitinol Venous Bare Metal Stents.

The purpose was to analyze the technical, clinical, and survival outcomes of our patients with malignant superior cava vein syndrome (SVCS) treated with endovascular approach and analyze the efficacy of different stent types used. It is an observational, retrospective, single-center study. From 2006 to 2023, 42 patients (32 male, 10 female, mean age 62 years, age range, 41-87 years) underwent percutaneous stent placement for malignant SVCS. One stainless steel stent (Wallstent) and 2 venous nitinol stent type (Sinus-XL, Venovo) were used. Follow-up mean was 276 days. A total of 53 stents were deployed. Clinical success was 97.6% in less 24 hours. Technical success was achieved in 97.6%. No complications were found except 1 patient died during the procedure due to stent migration and atrial dissociation (2.3%). Overall intraprocedural stent migration rate was 11.9% (18.8% stainless steel stent, 9.6% nitinol stent, p>0.05). Overall survival rates were 87.8%, 41.99%, and 34.12%, and overall primary patency rates were 100%, 93.3%, 91.6% at 1, 6, and 12 months, respectively. Endovascular treatment is a safe and effective therapeutic option for SVCS with high technical and clinical success rates and low complication and recurrence rates. The malignant superior cava vein syndrome is a rare clinical entity treated classically with radiation and chemotherapy with a slower response, or surgical bypass, which is an aggressive surgical technique. Endovascular treatment offers a low-invasive technique with quick clinical resolution and good permeability results. However, further studies are lacking to deal with procedure technical characteristics, stent type used, technical complications, and medium- and long-term patency studies. This study aims to evaluate all these items, analysing self-expanding stainless steel and nitinol venous bare metal stents, and add value to endovascular treatment, confirming the good results of this technique.

Transient P′ waves in a hyperkalemic cat: artifact or dissociation?

A 15-year-old Sphynx cat was referred for cervical ventroflexion, ataxia, and lethargy associated with hypokalemia. After administration of supplemental potassium, the cat became severely hyperkalemic. Transient P′ (vs. pseudo P′ waves) were detected on the electrocardiogram. Over the course of hospitalization, the cat's potassium normalized, and the abnormal P′ waves did not recur. These images are presented to highlight the differential diagnoses for this type of electrocardiogram. Diagnostic considerations included complete or transient atrial dissociation (as a rare consequence of hyperkalemia), atrial parasystole, and various electrocardiographic artifacts. Definitive diagnosis of atrial dissociation requires an electrophysiologic study or echocardiographic documentation of two independent atrial rhythms with associated mechanical activity, but these were unavailable in this case.

Abstract 9436: Treatment Options for Left Atrial Septal Pouch: A Case Report

Introduction: Left Atrial Septal pouch (LASP) is defined as an incomplete closure between the septum primum and septum secundum with an elongated septum secundum. This produces a crevice in the left atrium that functions as a source for static blood and atrial dissociation. This in turn could progress to the formation of thrombi within the left atrium that has the potential to embolize causing ischemic infarcts. Case Description: Here we present a 63 year old Hispanic female with a past medical history of paroxysmal atrial fibrillation on apixaban, recurrent strokes, dyslipidemia, and hypertension who presented with expressive aphasia, and prosopagnosia. Previously, the patient was reported of having two cardioembolic cerebral vascular accidents (CVA). Computed tomography of the brain demonstrated an old infarct of the left posterior parietal lobe. Patient was treated with intra-arterial tissue plasminogen activator of the left posterior cerebral artery and right middle cerebral artery. MRI demonstrated four acute punctate infarcts in the left frontal lobe consistent with embolic infarcts. TEE demonstrated a large patent foramen ovale (PFO), a prominent eustachian valve, and LASP. It was determined that her PFO and LASP were the culprit for her recurrent CVA despite appropriate AC. The PFO/LASP were successfully closed with an Amplatzer PFO occluder device. Patient was discharged home. Discussion: The LASP can function as a source of thrombus formation and atrial disassociation, which can cause embolic CVA. No guidelines exist on how to properly address a LASP. One option would be to use a PFO closure device to close LASP. Other options may include AC despite the absence of atrial fibrillation. Conclusions: In conclusion, further studies are necessary in order to establish the most appropriate management in patients with LASP.

Unilateral Atrial Ectopic Rhythm in a Golden Retriever

Background: Atrial ectopic rhythm is a type of supraventricular arrhythmia, originating in two distinct points in the atrial region. In the electrocardiographic (ECG) tracing, it is represented by independent depolarizations of sinus P waves and ectopic P waves. The occurrence of this disorder is rare, and the diagnosis criteria are the presence of the described waves within the basal rhythm. In humans, there have been reports related to severe heart failure with an unfavorable prognosis. The present report aimed to describe the clinical case of a dog with unilateral atrial ectopic rhythm without any underlying cardiac disorder.Case: A 8-year-old male golden retriever was brought to a veterinary clinic for a preoperative evaluation for lipoma removal in the right forelimb. On clinical examination, the owner stated that the patient was active, with no signs of easy fatigue or cough. The canine displayed normophagy, normodipsia, normoquezia, and normouria. On physical examination, he demonstrated a lymphatic temperament with tachypnea. The temperature and capillary filling time were within the normal range, with a normokinetic pulse. Cardiac auscultation revealed a mild grade I/VI murmur in mitral focus and an 80-bpm heart rate. Respiratory auscultation revealed the presence of harshy lung sounds. The cough reflex was positive; the Piparote test, negative. The blood test showed no noticeable changes in blood count and serum biochemistry. Systemic systolic blood pressure was 120 mmHg. On radiographic examination, no evidence of heart or lung abnormalities were identified. After the clinical evaluation, an ECG examination was performed; a unilateral atrial ectopic rhythm was observed with different frequencies between atrial and ventricular rhythm and with P (164°) and P waves (80°). On echocardiographic examination, no morphological abnormalities were seen, though trivial mitral insufficiency was identified in a color Doppler study. Blood was collected to measure electrolytes to check for possible electrolytic abnormalities; the results were within the normal range. The patient was released for and remained stable throughout the procedure, maintaining the rhythm detected during the transoperatory time. Upon reassessment in a new ECG examination, the arrhythmia persisted, suggesting that a primary lesion in the atrial tissue was present.Discussion: An atrial ectopic rhythm diagnosis requires a detailed study with the aim of ruling out heart diseases that may affect the propagation of the cardiac stimulus. However, no morphological or functional abnormalities of note that justified triggering stimuli for the ectopic rhythm were observed. In addition, based on the echocardiographic evaluation, myocardial function was preserved, supporting the canine’s release for the procedure. The suspicion of hydroelectrolytic alteration and hypoxia was present after discarding structural causes, though it was discarded due to normal laboratory results. The presence of ectopic P waves was due to the non-interference in the sinus P’ waves; consequently, they were found in the sinus heart rhythm. Upon assessing the ectopic P wave frequency, the atrial rhythm frequency was higher than the heart rate, juxtaposing the different irregular intervals within the atrial cycle. The rhythm alone may explain that its severity can be linked to the physical findings. This indicated that they did not influence the presentation of ectopia since the cardiac output, controlled by the sinus rhythm part, was responsible for maintaining the rhythm and the demand of the organism; the electrical conduction system, responsible for atrial systole, represents 15-25% of the blood ejection for the ventricular filling. Patients with rhythm disorders as described need guidance and follow-up for the early detection of clinical signs resulting from the destabilization of the condition.Keywords: atrial dissociation, supraventricular arrhythmia, electrocardiogram, dogs.

A Case of a Dog Whose Atrial Dissociation Disappeared After an Atropine Response Test

A Case of a Dog Whose Atrial Dissociation Disappeared After an Atropine Response Test

Inter/Intra-Atrial Dissociation in Patients With Maze Procedure and Its Clinical Implications: Pseudo-Block and Pseudo-Ventricular Tachycardia.

BackgroundSevere conduction delay and inter/intra‐atrial dissociation may occur in patients who undergo an extensive catheter ablation or a maze procedure for atrial tachyarrhythmia. We report a series of patients with inter/intra‐atrial dissociation that mimicked complete atrioventricular block or ventricular tachycardia.Methods and ResultsWe retrospectively reviewed the medical records of 7 patients who were referred for the evaluation of atrioventricular block (patients 1–6) or ventricular tachycardia (patient 7) that occurred after biatrial maze procedure and valvular surgery. During the electrophysiologic study, slow atrial or junctional escape rhythm dissociated from isolated atrial activity mimicked complete atrioventricular blocks. Intra‐atrial dissociation of the right atrium or left atrium was observed. Atrioventricular nodal conduction from the nondissociated atrium to the ventricle was preserved in all patients, while the conduction from the dissociated atrium was blocked. In patient 7, the pacing of the ventricle by tracking of atrial tachycardia from the nondissociated left atrium/coronary sinus mimicked ventricular tachycardia during pacemaker interrogation. A total of 5 patients received new permanent pacemaker implantations during the index hospitalization for the surgery (n=2) or as a deferred procedure (n=3) according to the treatment for sick sinus syndrome.ConclusionsPseudo‐atrioventricular block or pseudo‐ventricular tachycardia may occur because of inter/intra‐atrial dissociation after a maze procedure. The selection of patients for permanent pacemaker implantation should be determined based on the patient’s symptoms and the status of the escape pacemaker and not on the apparent atrioventricular block. Proper diagnosis is important to avoid unnecessary implantation of a pacemaker or a defibrillator.

Abstract 13148: Clinical Importance of Left Atrial Infiltration in Cardiac Transthyretin Amyloidosis

Introduction: The clinical significance of left atrial (LA) involvement and dysfunction in ATTR amyloidosis cardiomyopathy (ATTR-CM) has not been characterized. We sought to study: 1) LA pathology in heart specimens from ATTR-CM patients 2) LA stiffness and mechanics using echocardiographic speckle tracking (EST) in cardiac ATTR-CM 3) the association between parameters of atrial function and mortality. Methods: Congo red staining and immunohistochemistry was performed to assess amyloid in the atria from 5 ATTR-CM heart specimens. 2D EST was used to assess LA reservoir, conduit, contractile function and stiffness in 906 ATTR-CM patients (551 wt ATTR; 93 T60A ATTR; 241 V122I ATTR; and 21 other gene variants). Results: There was extensive ATTR amyloid infiltration in the 5 atria, with loss of normal architecture, infiltration and remodelling of vessels, capillary disruption and subendocardial fibrosis. EST demonstrated increased atrial stiffness [median (25th-75th quartile) 1.83 (1.15-2.92)] that remained independently associated with reduced survival, after adjusting for known prognostic variables (lnLA stiff: HR= 1.26, CI 1.07-1.57; p=.009). There was substantial impairment of the three phasic functional atrial components [reservoir 8.86(5.94-12.97)%; conduit 6.5(4.53-9.28)%; and contraction 4.0(2.29-6.56)%]. Atrial contractile function was absent in 21.6% of patients whose ECG showed sinus rhythm (SR)-atrial electro-mechanical dissociation (AEMD). AEMD was associated with a poorer prognosis compared to SR patients who had effective mechanical contraction (p <.0001). AEMD conferred a similar prognosis to patients in AF. Conclusions: The phenotype of ATTR-CM includes clinically significant infiltration of the atrial walls characterized by progressive loss of function and increased stiffness, a strong independent predictor of mortality. AEMD emerged as a distinctive functional phenotype identifying patients in SR with poor prognosis.

Atrial strain in cardiacATTR amyloidosis from pathophysiology to prognosis: is it time to rethink our approach to disease?

Abstract Background Left atrial (LA) involvement in cardiac ATTR amyloidosis (ATTR-CM) has never being explored. The aim of the study is to characterize the spectrum of changes in LA structure in ATTR-CM, the functional consequences on LA mechanics and the association with mortality. Methods We studied 936 patients with ATTR-CM who underwent prospective protocolized evaluations comprising ECG, full echocardiographic assessment, 6MWT, blood biomarkers sampling and survival assessment between 2000 and 2019. Reservoir (LAr), conduit (LAcd) and booster (LAcont) function were assessed according to current guidelines. LA stiffness (LAstiff) was estimated as the ratio between E/e' and LAr. The presence and extent of amyloid infiltration was assessed in two autopsied hearts from patients ATTR-CM with congo red staining and TTR antibodies. Results 936 patients with ATTR-CM were included, 567 with wtATTR-CM and 346 with hATTR-CM, of whom 246 had the V122I variant and 100 the T60A variant. LA indexed area was similar across the 3 genotypes, whilst LAr, LAcd and LAcont were significantly reduced in V122I patients compared to Wt and T60A patients (LAr: 10.4±6.4 vs 12.8±8.5 vs 8.59±5.7%, p<0.0001; LAcd: 5.6±5.0 vs 6.9±5.7 vs 4.0±3.6%, p<0.0001; LAcont 7.5±4.1 vs 8.2±4.9 vs 6.7±4.2%, p=0.023; in Wt, T60 and V122I respectively). Similarly, LAstiff was significantly worse in V122I compared to Wt and T60A (LAstiff: 2.39±2.62 vs 2.59±4.83 vs 2.96±2.88, p<0.0001, in Wt, T60 and V122I respectively). In the overall population, LAstiff remained independently associated with mortality, after adjusting for rhythm, systolic and diastolic functional parameters, ventricular longitudinal strain, genotypes, clinical variables and NAC staging system (lnLA stiff: HR=1.26, CI: 1.07–1.57; p=0.009). In the overall population, 584 patients were in sinus rhythm and 344 in atrial fibrillation, atrial flutter or atrial tachycardia (non-sinus rhythm group – NSR). Among patients in SR, 21.6% did not show a measurable LA mechanical contraction on strain analysis (LAcont). Patients in SR without LAcont on strain analysis showed similar structural and functional LA changes, NTproBNP, NYHA class, and 6MWT to NSR patients. Mortality of patients in SR with no LAcont was significantly reduced compared to patients in SR with LAcont and similar to patients in AF (Figure 1). On the two autopsies hearts there was extensive amyloid infiltration of TTR type in the atrial wall as confirmed with CR and TTR antibodies (Figure 1). Conclusions ATTR-CM is characterized by primary infiltration of the atrial walls with progressive loss of atrial function and increased stiffness. LA stiffness is a strong independent predictor of mortality after adjusting for known predictors. Atrial electro-mechanical dissociation emerged as a distinctive functional phenotype identifying patients in SR with worse prognosis. Figure 1 Funding Acknowledgement Type of funding source: None

A Tale of 2 Nodes After Orthotopic Heart Transplant

We report the case of a 30-year-old man who underwent orthotopic heart transplant via biatrial anastomosis technique. His post-operative electrocardiogram showed atrial dissociation, which is infrequently seen with newer surgical techniques in heart transplantation. (Level of Difficulty: Advanced.)

Unilateral atrial fibrillation - how common is atrial divorce?

Atrial fibrillation is the most common pathologic supraventricular tachycardia. It has many causes, is an expensive disease, impairs quality of life and leads to an increased risk of death. Atrial dissociation is characterised by the presence of two independent sets of P-waves. This peculiar abnormality may give rise to the scenario where one atrium is in atrial fibrillation while the other is in sinus rhythm. This is the first published case of atrial dissociation where the phenomenon is demonstrated by transmitral and transtricuspid pulsed wave Doppler.

症例 左右心房解離,その他種々の不整脈を呈した1症例

症例 左右心房解離,その他種々の不整脈を呈した1症例

A broad complex tachycardia with conflicting information from pacing manoeuvres

A patient with a biventricular implantable cardioverter defibrillator for heart failure had a recurrent broad complex tachycardia and underwent electrophysiologic testing. The tachycardia was induced only with ventricular pacing. There was a 1:1 atrioventricular relationship with simultaneous atrial and ventricular activation. However, atrial pacing during tachycardia suggested atrial dissociation from the circuit. The findings, potential mechanisms, and treatment are discussed.

Electrocardiographic and echocardiographic evidence of atrial dissociation

A 4-year-old Boxer dog with a history of ventricular premature contractions was evaluated for anorexia. An electrocardiogram revealed atrial dissociation and an echocardiogram supported simultaneous mechanical atrial systole with the ectopic atrial electrical activity. This case and the supporting images provide further credence to the existence of atrial dissociation.

Clinically silent atrial dissociation in a dog

A Labrador retriever, presented for a routine yearly wellness exam, shows on ECG a normal sinus rhythm with first degree atrioventricular blockade and atrial dissociation (AD). A detailed cardiologic examination was performed including thoracic radiography, echocardiography and blood pressure measurement, all of which were considered normal. The dog described in this current report was re-examined several times over the subsequent 2 years and no clinical signs of heart failure, heart disease or other diseases were recognized, the AD appears to have been benign.

Is this atrial parasystole, atrial dissociation, or an artifact?

Is this atrial parasystole, atrial dissociation, or an artifact?

Histopathological findings on a case of atrial dissociation and partial atrial standstill with dilated cardiomyopathy

Histopathological findings on a case of atrial dissociation and partial atrial standstill with dilated cardiomyopathy

Heterogeneity of anterograde fast-pathway and retrograde slow-pathway conduction patterns in patients with the fast-slow form of atrioventricular nodal reentrant tachycardia: electrophysiologic and electrocardiographic considerations.

This study sought to define the electrophysiologic and electrocardiographic characteristics of fast-slow atrioventricular nodal reentrant tachycardia (AVNRT). In fast-slow AVNRT the retrograde slow pathway (SP) is located in the posterior septum, whereas the anterograde fast pathway (FP) is located in the anterior septum; however, exceptions may occur. Twelve patients with fast-slow AVNRT were studied. To determine the location of the retrograde SP, atrial activation during AVNRT was examined while recording the electrograms from the low septal right atrium (LSRA) on the His bundle electrogram and the orifice of the coronary sinus (CS). Further, to investigate the location of the anterograde FP, single extrastimuli were delivered during AVNRT both from the high right atrium and the CS. The CS activation during AVNRT preceded the LSRA in six patients (posterior type); LSRA activation preceded the CS in three patients (anterior type), and in the remaining three both sites were activated simultaneously (middle type). In the anterior type, CS stimulation preexcited the His and the ventricle without capturing the LSRA electrogram (atrial dissociation between the CS and the LSRA), suggesting that the anterograde FP was located posterior to the retrograde SP. In the posterior and middle types, high right atrial stimulation demonstrated atrial dissociation, suggesting that the anterograde FP was located anterior to the SP. In the posterior and middle types, retrograde P waves in the inferior leads were deeply negative, whereas they were shallow in the anterior type. Fast-slow AVNRT was able to be categorized into posterior, middle and anterior types according to the site of the retrograde SP. The anterior type AVNRT, where an anteriorly located SP is used in the retrograde direction and a posteriorly located FP in the anterograde direction, appears to represent an anatomical reversal of the posterior type which uses a posterior SP for retrograde and an anterior FP for anterograde conduction. Anterior type AVNRT should be considered in the differential diagnosis of long RP (RP > PR intervals) tachycardias with shallow negative P waves in the inferior leads.

Involvement of a Nodofascicular Connection in Supraventricular Tachycardia with VA Dissociation

We present the case of a patient with episodes of supraventricular tachycardia and atrial dissociation that were terminated by either adenosine or verapamil. Involvement of an accessory pathway was shown by ventricular extrastimuli, elicited during His-bundle refractoriness, that interrupted the tachycardia or advanced the next His potential. The tachycardia circuit was demonstrated to be confined to the nodofascicular region based on the exclusion of surrounding tissues. Atrial activity, including that in the perinodal region, was totally dissociated during tachycardia. The lowest part of the circuit was determined to be located above the Hisian bifurcation, as multiple episodes with either a right or left bundle branch configuration during tachycardia did not modify the HH cycle. The ventricular septum summit was determined not to be involved, as no preexcitation was present during tachycardia or atrial pacing, and the right bundle branch was not part of the circuit. Radiofrequency current applied beneath the tricuspid valve at the His region successfully eliminated the nodofascicular connection with preservation of 1:1 AV conduction. The anatomical substrate underlying the abnormal connection may be either nodofasciculoventricular Mahaim fibers or a duality or dispersion of the nodo-Hisian conducting system.

Demonstration of Right and Left Atrial Dissociation by Atrial Rapid Pacing or Extrastimulation During Fast‐Slow (Uncommon) Form of Atrioventricular Nodal Reentrant Tachycardia

Some recent works suggest that extranodal atrial fibers may form part of the reentry circuit in the atrioventricular (AV) nodal reentrant tachycardia (AVNRT). This hypothesis is based on the fact that the perinodal dissection successfully abolished AVNRT while preserving intact AV conduction. Apart from the surgical success, the electrophysiological evidence supporting this hypothesis has not been demonstrated, especially in the uncommon (fast-slow) form of AVNRT. We present some electrophysiological evidence suggesting atrial participation in eight patients with the fast-slow form of AVNRT. During the tachycardia, rapid pacing or extrastimulation was done from the orifice of the coronary sinus (CS) and the right atrium (RA), while recording the electrograms of the CS and the low septal RA. In seven patients, right and left atrial dissociation was demonstrated during pacing from the RA, while in the remaining one this was demonstrated from the CS. The interatrial dissociation will be unlikely if the intranodal reentry circuit connects with the atria via a single upper common pathway. This suggests that the upper turnaround of the reentry circuit involves atrial tissue and that the extranodal accessory pathway with long conduction times may form the ascending limb of the circuit (atrionodal reentry). Alternatively, the reentry circuit is entirely intranodal and two or more connecting pathways are present between the atria and the circuit.

Segmental atrial fibrillation resulting in chronic atrial dissociation: A case report

Atrial arrhythmias are diagnosed on the basis of the analysis of P wave morphology, timing and rate, the surface electrocardiogram, and intracardiac recordings. Recent intracardiac studies have demonstrated dissimilar atrial rhythms with direct intra-atrial recordings, the former otherwise not evident on the surface ECG (Zipes et al. 1972, Wu et al. 1975, Friedman et al. 1974, Gomes et al. 1981). This paper reports the electrocardiographic diagnosis of atrial dissociation made on the surface electrocardiogram. The findings suggest the following: (1) That sinus rhythm exists, with the dominant sinus rhythm depolarizing the major portion of the right as well as the left atrium; (2) Atrial fibrillation localized specifically to lead III, and at times to leads III and AVL, on the surface electrocardiogram; and (3) Intraesophageal recordings and echocardiography revealed an area of the posterior right and left atria that had wall motion abnormalities and electrical activity compatible with those of atrial fibrillation.