Electrical stimulation mapping of the pulmonary artery in swine: impact on pulmonary artery denervation procedure for pulmonary hypertension

Introduction Pulmonary artery denervation (PAD) has been recently shown to decrease pulmonary artery (PA) pressure. However, there is a lack of data related to target sites for ablation. Purpose To determine the optimal PA ablation sites based on response to high-frequency stimulation mapping and anatomical areas where radiofrequency ablation (RFA) should be avoided due to the risk of severe collateral damage. Methods A total of 17 Landrace swines were included into the study. PA angiography, hemodynamic measurements by right heart-sided catheterization and electrophysiological mapping (EM) using low (cycle length 330 ms) and high-frequency (33Hz) stimulation (HFS). Stimulation was performed at PA bifurcation and proximal parts of the main PA branches with a 5-mm distance between points; catheter manipulation was performed under fluoroscopic guidance in multiple projections. Points with evoked reactions were tagged on a 3-dimentional PA model in each case. In order to confirm reproducibility of reactions, HFS was performed at least twice at each point with a response. PA models obtained from all animals were combined in one for the final analysis. RFA using an open-irrigated catheter (40 Watts; 40 s; irrigation 30 ml/min) were performed at sites with evoked reactions. Repeated HFS was performed at ablation sites. After the procedure all animals were euthanized and underwent an autopsy study. Results Low-frequency stimulation (LFS) allowed to define areas of ventricular capture (VC) where HFS was avoided due to ventricular fibrillation induction risk. During HFS the following evoked responses were documented: sinus bradycardia, sinus rhythm (SR) acceleration, phrenic nerve capture (PNC), and laryngeal recurrent nerve capture. HFS captured left and right phrenic nerves in all animals at PA trunk, and its course was tagged (Figure 1). Laryngeal recurrent nerve capture was found in 4 (23%) of animals. Atrial capture was found in all cases while LFS at the anterior aspects of both PAs even at low output, and this precluded evaluation of neural autonomic reactions in these areas. Evoked bradycardia and SR acceleration were both found during HFS in 10 (59%) of cases each. Following RFA application evoked reactions were non-reproducible in all cases. RFA was applied in areas where no PNC or VC points were observed. An autopsy study confirmed the presence of RF-induced lesions of the PA wall. Conclusions There are two important findings of our study. First, stimulation-guided PA mapping is feasible and reveals several specific responses to HFS. Ablation at points with responses leads to non-reproducibility of the evoked reactions, confirming that transcatheter RFA may be an adequate approach for PA denervation. Second, previously proposed circular PA ablation might be associated with phrenic and laryngeal recurrent nerve damage. Stimulation-guided PA denervation can be proposed as a safer procedure, and should be evaluated in clinical settings. Figure 1. PA schematic representation Funding Acknowledgement Type of funding source: Public grant(s) – National budget only. Main funding source(s): Russian Foundation for Basic Research

Endoscopic treatment of esophageal injury after thyroidectomy – a case report

The most common complications after thyroidectomy are postoperative neck hematoma, laryngeal recurrent nerve injury and hypoparathyroidism. [1] However, iatrogenic cervical esophageal perforation is a very rare repercussion of this procedure. In literature there are a few reported cases concerning that complication. We want to report a case of a patient with severe esophageal injury resulted from thyroidectomy.

Laryngeal hemiplegia in the horse: an update

Laryngeal hemiplegia is a progressive upper airway dysfunction in the horse. It is not only seen in thoroughbred racehorses but also in warmblood horses, draft horses and in ponies. The condition is most frequently seen on the left side. The left laryngeal recurrent nerve gradually loses function and the function of the left cricoarythenoideus dorsalis muscle is compromised. This condition is most often idiopathic. It possibly leads to exercise intolerance but a respiratory noise is often the primary complaint of the owner. Right sided laryngeal hemiplegia is almost always related to other pathologies causing the nerve to malfunction. The diagnosis is not always easy because of the restricted availability of endoscopy in the field. A better understanding of laryngeal ultrasound examination might offer a new possibility in diagnosing laryngeal hemiplegia. If abnormal inspiratory sound is the only problem, laser treatment alone can be satisfactory. If the horse shows clear signs of exercise intolerance, further treatment is needed. If correctly executed, the outcome of laryngoplasty is good. Other techniques, like nerve grafting and pacemakers, are being explored and might even be regarded as better alternative treatments in the future, as these are more physiologic compared to laryngoplasty. In sporthorses presented with idiopathic laryngeal neuropathy without postoperative complications, the prognosis is good.

PS01.146: THE ANALYSIS OF THE SAFETY OF A MODIFIED LEFT RECURRENT LARYNGEAL LYMPH NODES DISSECTION IN THORACOSCOPIC ESOPHAGEAL CARCINOMA SURGERY

Background To explore the thoroughness and safety of a modified left recurrent laryngeal lymph nodes dissection in thoracoscopic esophageal carcinoma surgery. Methods Retrospectively analyzed the clinical data of 136 patients with the left recurrent laryngeal lymph nodes dissection from October 2015 to October 2017 in the First Hospital Affiliated to Xiamen University. 67 cases were divided to the traditional dissection group (double lumen endotracheal intubation, 90 ° lateral position) and 69 cases were classified to the modified dissection group (single cavity tracheal intubation, thoracic CO2 positive pressure ventilation, lateral prone position and esophageal suspension technology). Observed and compared the left laryngeal recurrent nerve lymph nodes cleaning and time, intraoperative complications including thoracic duct injury, tracheal injury, hoarseness and pneumonia. Results The cleaning time of the modified dissection group (23 + 8 min) was significantly less than that of the traditional cleaning group (32 plus or minus 5min) (P < 0.01). 5 patients occurred left laryngeal nerve injury in the modified dissection group, with statistically significance (P < 0.01), less than traditional dissection group of 12 patients. The modified dissection method improves the exposure of intraoperative field, the probability of thoracic duct and tracheal injury (1/69, 0/69) were lower than the traditional group (2/67, 1/67), but the difference was not statistically significant (P > 0.05). Moreover, there was no significant difference in lymph nodes metastasis and complications incidence rate (P > 0.05). Conclusion The modified dissection method, including single cavity tracheal intubation, thoracic CO2 positive pressure ventilation, lateral prone position and using esophageal suspension technology, can achieve good operation field exposure, the left recurrent laryngeal lymph nodes ‘the whole block’ cleaning, and the greatest degree protection of laryngeal recurrent nerve, thoracic duct, trachea and other organs damage. It is worthy of clinical popularization and application. Disclosure All authors have declared no conflicts of interest.

NEUROMONITORING THE BRANCHES OF THE RECURRENT NERVE DURING THYROIDECTOMY

The lesions of the laryngeal nerves are the most severe long term complications after thyroidectomy. Visual identification of the recurrent laryngeal nerve during thyroid surgery has been recommended in many studies as the golden standard of RLN treatment. The non recurrent laryngeal nerve should always be taken into consideration in order to avoid accidental injury during thyroid surgery. Laryngeal recurrent nerve can be difficult to identify because of rare anatomical variants, extra laryngeal branches, or in complicated thyroid operations, such as voluminous goiter or thyroid cancer. Intraoperative nerve monitoring is secure for the patient, easy to use and useful in showing the integrity of laryngeal recurrent nerve, both during and after surgery. The Departament of Surgery, Valcea Country Hospital, from January 2014 to April 2015, developed a prospective study which enrolled 123 patients who underwent thyroid interventions with neuromonitoring and all had been treated by the same surgeon. The signal obtained from RLN localization, 215 nerves (96%), from a total of 222 , show a clear and reliable EMG response. 7 nerves (3%) were not received through EMG signal. In 3 cases involving 5 RLN there was a false negative result caused by electrode malposition and in 2 cases the RLN was injured during surgery.Clinical evolution of the procedure and more extended studies are needed to show if intraoperative monitoring decreases the rate of recurrent laryngeal nerves iatrogenic injury.