New onset postural orthostatic tachycardia syndrome following ablation of AV node reentrant tachycardia

Sick Sinus Syndrome Can Be Associated with Postural Tachycardia Syndrome and Inappropriate Sinus Tachycardia Syndrome

As a known phenomenon, crossover between sinus node dysfunction and common atrial tachyarrhythmias—most notably, atrial fibrillation and atrial flutter—in older individuals has previously been seen. Here, we present one of the first case series demonstrating a similar relationship between sinus node dysfunction and much rarer etiologies of tachyarrhythmia—that is, postural tachycardia syndrome and inappropriate sinus tachycardia. The exact pathological mechanisms behind these arrhythmias as well as the observation of concurrent nodal dysfunction are poorly understood. Here, we propose both potential mechanistic pathways as well as an initial treatment algorithm for sinus node dysfunction based upon the existing evidence.

A Case of Intermittent Preexcitation and Palpitations: More than Meets the Eye

We discuss the case of a 22-year-old female who presented to the clinic experiencing recurrent palpitations. She was also found to have intermittent preexcitation on her electrocardiogram (ECG). Her palpitations were attributed to stress. Previously, she had gone to the emergency department a few times and was diagnosed with sinus tachycardia. Her ECG revealed a right-sided accessory pathway. Given her atypical finding of orthodromic reciprocating tachycardia, a 30-day event monitor was implanted, which revealed that one episode was correlated with sinus tachycardia, with a heart rate of 120 bpm. She mentioned experiencing other episodes that were severe, but she did not activate the monitor manually at the time of these incidents. After a long discussion with the patient about available management options for her symptoms, it was decided to proceed with long-term monitoring with an implantable loop recorder to gather better symptom–rhythm correlation data. At six months after surgery, the patient experienced multiple manually triggered transmissions from her device, which were all consistent with sinus tachycardia. She had no episode suggestive of any supraventricular tachycardia and is thus being treated for inappropriate sinus tachycardia. This case highlights the importance of gathering adequate symptom–rhythm correlation data before pursuing more invasive treatment options for an arrhythmic etiology in low-risk patients.

Slow pathway ablation for typical atrioventricular nodal re-entrant tachycardia significantly alters the autonomic modulation of atrioventricular conduction

PURPOSE

Atrioventricular (AV) conduction turbulence, biphasic dromotropic response of AV node to single ventricular premature contraction (VPC), consists of early shortening and later prolongation of AV conduction intervals due to the direct electrophysiological mechanisms and perturbation in autonomic modulation. We investigated the acute effect of radiofrequency catheter ablation of slow pathway on AV turbulence.

METHODS

The electrophysiological study was performed in 18 patients (7 men, mean age 49 ± 15 years) undergoing catheter ablation for AV nodal reentrant tachycardia. The stimulation protocol consisting of series of isolated VPC (coupling interval of 273 ± 23 ms) delivered from right ventricle apex during constant atrial pacing at 100 bpm was performed immediately prior to and 8 ± 4 min after successful slow-pathway ablation. Averaged post-VPCs profiles of AV conduction intervals were analyzed by purpose-written software. The descriptors of AV turbulence, turbulence onset (TOAV), turbulence slope (TSAV), and AV recovery (R AV) were assessed.

RESULTS

Slow-pathway ablation suppressed the AV nodal responsiveness to VPC as evidenced by significant reduction of AV turbulence indices: TOAV: -6.4 ± 7.5 % vs. -4.3 ± 6.1 % (p < 0.05); TSAV: 2.0 ± 2.6 ms/RRi vs. 1.0 ± 0.7 ms/RRi (p < 0.05); and R AV: -13.8 ± 7.3 % vs. -6.5 ± 12.7 % (p < 0.05).

CONCLUSIONS

Slow-pathway ablation significantly attenuated both vagal and non-autonomic modulation of AV nodal conduction. This effect is likely due to direct thermal injury of AV node associated with the change of properties of AV nodal fast-pathway although specific alteration of peri-AV nodal ganglionated plexi or their neural inputs into the AV node cannot be excluded.

Postural orthostatic tachycardia syndrome after surgical correction of an aortic coarctation: a case report

INTRODUCTION

We report a case of postural tachycardia syndrome occurring after the surgical correction of an aortic coarctation, and coexisting with upper airway resistance syndrome.

CASE PRESENTATION

A 29-year-old Caucasian man complained of extreme fatigue, daytime sleepiness, shortness of breath on exertion, light-headedness and general weakness on standing. These symptoms began shortly after the surgical correction of an aortic coarctation and became progressively more debilitating, impairing any daily activity. An extensive work-up revealed postural tachycardia syndrome and a coexisting sleep-related breathing disorder, characterized as upper airway resistance syndrome.

CONCLUSION

This is the first reported case describing the occurrence of postural tachycardia syndrome after the surgical correction of an aortic coarctation. This case also provides evidence for the suggestion that this syndrome may coexist with upper airway resistance syndrome, although the exact nature of their relationship must still be better established.

Heart rate variability and atria function in children at late follow-up evaluation after atrioventricular node slow-pathway radiofrequency ablation

This study was designed to assess the changes in the conductive system, autonomic dysfunction, and global and regional function of the atria and ventricles in children late after slow-pathway radiofrequency ablation (RFA). The study enrolled 22 children, who has successfully undergone RFA 2 to 5 years previously (RFA group) and 20 healthy children (control group). Electrophysiologic study was performed for the RFA group. Holter monitoring and echocardiography were performed for all the children. At a late follow-up assessment, the RFA children were free of paroxysms, whereas 8 of the 22 children (36%) reported transient palpitations. Both mean and maximal heart rates (HR) were significantly increased, whereas indices of HR variability (% of successive normal sinus RR intervals exceeding 50 ms [pNN50], root mean square of the successive normal sinus RR interval difference [rMSSD], high-frequency component [HFC]) were significantly decreased in the RFA group compared with preablation and control data. Left atrial (LA) and right atrial (RA) volumes were significantly higher, and atria deformation indices were significantly lower in the RFA group. Correlations were found between the mean HR and the volumes of LA (r = 0.477; p < 0.001) and RA (r = 0.512; p < 0.001). A negative correlation between the maximal LA volume and the longitudinal strain rate (SR) during relaxation (r = -0.476; p = 0.03) and a positive correlation between the minimal LA volume and both longitudinal SR (r = 0.361; p = 0.03) and strain (ε) (r = 0.375; p = 0.024) during contraction were shown. These data suggest a possible link between atrial dysfunction and the hyperadrenergic state after RFA.