Late Outcomes of Surgical Ablation for Inappropriate Sinus Tachycardia

Abstract

Background. Inappropriate sinus tachycardia (IST) is a rare clinical disorder characterized by an elevated resting heart rate and an exaggerated rate response to exercise or autonomic stress. Pharmacologic therapy and catheter ablation are considered first-line treatments for IST but can yield suboptimal relief of symptoms. The results of surgical ablation at our center were reviewed for patients with refractory IST. Methods. Between 1987 and 2018, 18 patients underwent surgical sinoatrial (SA) node isolation for treatment-refractory IST. All 18 patients had previously failed pharmacologic therapy, and 15 patients had failed catheter ablation of the SA node. Results. Ten patients underwent a median sternotomy, and 8 patients underwent a minimally invasive right thoracotomy. The SA node was isolated with the use of surgical incisions, cryoablation, or bipolar radiofrequency ablations. Sinus tachycardia was eliminated in 100% of patients in the immediate postoperative period. Long-term follow-up data were available for 17 patients, with a mean follow-up of 11.4 ± 7.9 years. At last follow-up, 100% of patients were free from recurrent symptomatic IST. More than 80% of patients were completely asymptomatic, whereas 3 patients reported occasional palpitations. Four patients were on b-blockers, and 5 patients required subsequent pacemaker implantation. All 8 patients who underwent minimally invasive isolation were in normal sinus rhythm at last follow-up, and only 1 patient complained of palpitations. Conclusions. Surgical isolation of the SA node is a feasible treatment for IST refractory to pharmacologic therapy and catheter ablation. A minimally invasive surgical approach offers a less morbid alternative to traditional median sternotomy.

Innervation and Neuronal Control of the Mammalian Sinoatrial Node: A Comprehensive Atlas

“…Adjunctive ablation of the posterior atrial GP, which is located between the SVC and aorta, may have abolished SGS-induced tachycardia, as murine and canine models have suggested TH-positive fibers course via the medial aspect of the SVC to the SAN (63,64). As some cardiothoracic surgeons are exploring SAN denervation for SAN ablation for inappropriate sinus tachycardia, these findings suggest that the region of the RAGP-SAN should be spared (65).…”

“…Heterogeneity in targets for intervention across studies has yielded variable results, and the approach of ablating GPs does not selectively target neurons, as afferent, efferent and local circuit neurons are likely impacted (9,76). Inappropriate sinus tachycardia has emerged as a consequence of disrupting parasympathetic fibers to the SAN, although SAN denervation has also been applied to cases of inappropriate sinus tachycardia (65,77). In studies of GP ablation for sinus bradycardia and syncope, radiofrequency ablation of the RAGP resulted in increased HRs and a 95% reduction in syncope, respectively, but the long-term consequences of such cardioneuroablation are, as yet, unclear (61,62).…”

The sinoatrial node in medication‐resistant inappropriate sinus tachycardia: To modify or to ablate?

“…Surgical treatment of IST has proposed a solution to the latter conflict when isolating the SA node with a wide cuff of surrounding atrial muscle 19 . And with the advent of bipolar RF clamps and minimally invasive cardiac surgical techniques with thoracoscopic guidance, this approach appears more appealing than before, especially when combined with endocardial ablation 19 . But again, current data specifies employing these techniques in highly selected cases.…”

“…Although the number of patients in the available studies is generally small, both procedures have documented an encouraging success rate in the short‐term, while being less impressive in the long‐term. It has been hypothesized that this discrepancy is due to the relatively large potential area of atrial pacemaker cells 18 ; modification or ablation may fail to ablate or isolate all the pathways that comprise the functional SA node because they often target the anatomic part and the area of earliest atrial activation 19 . Others have explained that the long‐term slowing in rhythm fails because these procedures inconsistently produce transmural lesions in the right atrium.…”

“…Others have explained that the long‐term slowing in rhythm fails because these procedures inconsistently produce transmural lesions in the right atrium. Surgical treatment of IST has proposed a solution to the latter conflict when isolating the SA node with a wide cuff of surrounding atrial muscle 19 . And with the advent of bipolar RF clamps and minimally invasive cardiac surgical techniques with thoracoscopic guidance, this approach appears more appealing than before, especially when combined with endocardial ablation 19 .…”