Partial atrial standstill: a case report

Left Bundle Branch Area Pacing in a Giant Atrium With Atrial Standstill: A Case Report and Literature Review

Atrial standstill (AS) is a rare condition defined by the lack of atrial electrical and mechanical activities. It is usually clinically manifested as symptomatic bradycardia, which requires permanent pacemaker (PPM) implantation. Traditional right ventricular apical pacing causes electrical and mechanical dyssynchrony resulting in left ventricular dysfunction, heart failure, and arrhythmias. As a novel physiological pacing strategy, left bundle branch area pacing (LBBaP) has demonstrated effectiveness and safety in recent years, but its application in exceptional conditions is rarely reported. We report the case of a 47-year-old female, who was diagnosed with AS complicated with a giant atrium, and successfully received a single-chamber PPM with LBBaP.

Indications for permanent pacing in dogs and cats

Pacemaker implantation is considered as a standard procedure for treatment of symptomatic bradycardia in both dogs and cats. Advanced second-degree and third-degree atrioventricular blocks, sick sinus syndrome, persistent atrial standstill, and vasovagal syncope are the most common rhythm disturbances that require pacing to either alleviate clinical signs or prolong survival. Most pacemakers are implanted transvenously, using endocardial leads, but rarely epicardial leads may be necessary. To decide whether a patient is a candidate for pacing, as well as which pacing modality should be used, the clinician must have a clear understanding of the etiology, the pathophysiology, and the natural history of the most common bradyarrhythmias, as well as what result can be achieved by pacing patients with different rhythm disturbances. The goal of this review was, therefore, to describe the indications for pacing by evaluating the available evidence in both human and veterinary medicine. We described the etiology of bradyarrhythmias, clinical signs and electrocardiographic abnormalities, and the choice of pacing modality, taking into account how different choices may have different physiological consequences to selected patients. It is expected that this review will assist veterinarians in recognizing arrhythmias that may require permanent pacing and the risk-benefit of each pacing modality and its impact on outcome.

Atrial standstill presenting as cerebral infarction in a 7-year-old girl

Atrial standstill is a rare arrhythmia defined by the absence of mechanical and electrical activity in the atria. Few cases of atrial standstill have been described in children, none of which have presented with cerebral infarction confirmed by imaging. We report a unique case of a 7-year-old girl presenting with expressive aphasia, central facial palsy and irregular pulse with cerebral infarction secondary to atrial standstill. This case illustrates that cardiogenic cerebral embolism in children can be caused by rare conditions like atrial standstill and should be considered in paediatric patients undergoing evaluation for stroke. There are no established treatment guidelines for atrial standstill. We recommend that treatment be directed towards any potential underlying cause. All patients with atrial standstill should receive long-term oral anticoagulation treatment and a permanent cardiac pacemaker implant to reduce the risk of further strokes or other cardiac events.

Persistent atrial standstill following the Cox-maze III procedure: reversal with sustained atrial pacing

Atrial standstill is a rare disorder of cardiac rhythm that is characterized by total absence of electrical activity in one or both atria. We report herein the case of a patient with atrial fibrillation and symptomatic 4.0 s pauses who received a ventricular demand pacemaker. The patient later underwent mitral valve replacement with a pericardial tissue valve and the Cox-maze III procedure for symptomatic mitral stenosis and atrial fibrillation. Following surgery, he developed atrial standstill and became pacemaker dependent. The pacemaker was later revised to an atrioventricular sequential pacemaker. Twelve hours after revision, atrioventricular sequential pacing was noted and mechanical function of the atria was confirmed by Doppler echocardiography.

Left Atrial Inexcitability in Children With Congenital Lupus-Induced Complete Atrioventricular Block

Background

Congenital atrioventricular block is a well‐established immunologic complication of maternal systemic lupus erythematosus. We sought to further characterize the electrophysiological manifestations of maternal systemic lupus erythematosus on neonatal atria.

Methods and Results

Cases of isolated congenital atrioventricular block treated at our center over the past 41 years were identified. Data were extracted from clinical charts, pacemaker interrogations, ECGs, echocardiograms, and histopathological reports, when available. Of 31 patients with isolated congenital atrioventricular block, 18 were negative for maternal antibodies and had normal epicardial atrial sensing and pacing thresholds. In contrast, 12 of 13 patients with positive maternal antibodies had epicardial pacemakers, 5 (42%) of whom had left atrial (LA) inexcitability and/or atrial conduction delay. In 3 patients, the LA could not be captured despite high‐output pacing. The fourth patient had acutely successful LA appendage and left ventricular lead placement. At early follow‐up, an increased delay between the surface P‐wave and intracardiac atrial depolarization was observed, indicative of atrial conduction delay. The fifth patient exhibited LA lead dysfunction, with atrial under‐sensing and an increased capture threshold, 2 weeks after implantation. Biopsies of LA appendages performed in 2 patients showed no evidence of atrial fibrosis or loss of atrial myocytes.

Conclusions

Herein, we report previously undescribed yet prevalent electrophysiological ramifications of maternal systemic lupus erythematosus, which extend beyond congenital atrioventricular block to encompass alterations in LA conduction, including LA inexcitability. These manifestations can complicate epicardial pacemaker implantation in newborns. In the absence of histological evidence of extensive atrial fibrosis, immune‐mediated functional impairment of electrical activity is suspected.