Effects of head-up tilt after stellate ganglion block on QT interval and QT dispersion

Validation and Reliability of a Novel Vagus Nerve Neurodynamic Test and Its Effects on Heart Rate in Healthy Subjects: Little Differences Between Sexes

Background

The vagus nerve (VN), also called the pneumogastric nerve, connects the brainstem to organs contained in the chest and abdomen. Physiologically, VN stimulation can rapidly affect cardiac activity and heart rate (HR). VN neuropathy can increase the risk of arrhythmias and sudden death. Therefore, a selective test of VN function may be very useful. Since peripheral neurodynamic tests (NDT) are reliable for the assessment of neuropathies in somatic nerves, we aimed to validate a novel NDT to assess VN activity, namely, the VN-NTD.

Methods

In this cross-sectional double-blind, sex-balanced study, 30 participants (15 females) completed a checklist of autonomic dysfunction symptoms. During the VN-NDT administration, HR and symptoms (i.e., mechanical allodynia) were monitored in parallel to a real-time ultrasonography imaging (USI) and motion capture analysis of the neck. The VN-NDT impact on HR and its accuracy for autonomic symptoms reported in the last 7 days were tested.

Results

The VN-NDT induced a significant HR reduction of about 12 and 8 bpm in males and females [t(1, 119) = 2.425; p < 0.017; η_p² = 0.047, 95% confidence interval (CI): 0.93–9.18], respectively. No adverse events were observed during VN-NDT. A substantial interexaminer agreement between the evaluators in symptoms induction by VN-NDT was detected [F(1, 119) = 0.540; p = 0.464; η_p² = 0.005, low effect]. Notably, mechanical allodynia accuracy for gastrointestinal dysfunctions was excellent (p < 0.05; 95% CI: 0.52–0.73; p < 0.001; 95% CI: 0.81–0.96).

Conclusions

The novel VN-NDT is a valid and accurate test capable of detecting VN activation with high sensitivity. Data provided are suitable for both sexes as a hallmark of HR variation due to VN normal response. The proposed VN-NDT may be reliable as daily routine neurological examination tests for the evaluation of neuropathic signs related to neuroinflammation of the VN.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT04192877.

Cardiac Denervation for Arrhythmia Treatment with Transesophageal Ultrasonic Strategy in Canine Models

Stellate ganglion (SG) modification has been investigated for arrhythmia treatment. In this study, transesophageal SG imaging and intervention were explored using a homemade 30F integrated focused ultrasonic catheter in healthy mongrel canines in vivo. Anatomic details of SGs were ultrasonically imaged and evaluated. SG had a heterogeneous echoic structure and characteristic profiles sketched by hyper-echoic outlines in an ultrasonogram. Left SGs in the experimental group were successfully ablated through the esophagus under ultrasonic guidance provided by the catheter itself. Two weeks after the ablation, the QT and QTc of the experimental group decreased compared with those of the sham group and at baseline (both p values < 0.001). Histologic examination revealed that left SGs were destroyed. No major complications were observed. This approach may be further explored as a method for ganglia remodeling evaluation and as a strategy of ganglia modification for arrhythmia and for other diseases.

Augmentation of cardiac sympathetic tone by percutaneous low-level stellate ganglion stimulation in humans: a feasibility study

Modulation of human cardiac mechanical and electrophysiologic function by direct stellate ganglion stimulation has not been performed. Our aim was to assess the effect of low-level left stellate ganglion (LSG) stimulation (SGS) on arrhythmias, hemodynamic, and cardiac electrophysiological indices. Patients undergoing ablation procedures for arrhythmias were recruited for SGS. A stimulating electrode was placed next to the LSG under fluoroscopy and ultrasound imaging; and SGS (5-10 Hz, 10-20 mA) was performed. We measured hemodynamic, intracardiac and ECG parameters, and activation recovery intervals (ARIs) (surrogate for action potential duration) from a duodecapolar catheter in the right ventricular outflow tract. Five patients underwent SGS (3 males, 45 ± 20 years). Stimulating catheter placement was successful, and without complication in all patients. SGS did not change heart rate, but increased mean arterial blood pressure (78 ± 3 mmHg to 98 ± 5 mmHg, P < 0.001) and dP/dt max (1148 ± 244 mmHg/sec to 1645 ± 493 mmHg/sec, P = 0.03). SGS shortened mean ARI from 304 ± 23 msec to 283 ± 17 msec (P < 0.001), although one patient required parasympathetic blockade. Dispersion of repolarization (DOR) increased in four patients and decreased in one, consistent with animal models. QT interval, T-wave duration and amplitude at baseline and with SGS were 415 ± 15 msec versus 399 ± 15 msec (P < 0.001); 201 ± 12 msec versus 230 ± 28 msec; and 0.2 ± 0.09 mV versus 0.22 ± 0.08 mV, respectively. At the level of SGS performed, no increase in arrhythmias was seen. Percutaneous low-level SGS shortens ARI in the RVOT, and increases blood pressure and LV contractility. These observations demonstrate feasibility of percutaneous SGS in humans.

Hypotensive bradycardic events during shoulder arthroscopic surgery under interscalene brachial plexus blocks

Sudden, profound hypotensive and bradycardic events (HBEs) have been reported in more than 20% of patients undergoing shoulder arthroscopy in the sitting position. Although HBEs may be associated with the adverse effects of interscalene brachial plexus block (ISBPB) in the sitting position, the underlying mechanisms responsible for HBEs during the course of shoulder surgery are not well understood. The basic mechanisms of HBEs may be associated with the underlying mechanisms responsible for vasovagal syncope, carotid sinus hypersensitivity or orthostatic syncope. In this review, we discussed the possible mechanisms of HBEs during shoulder arthroscopic surgery, in the sitting position, under ISBPB. In particular, we focused on the relationship between HBEs and various types of syncopal reactions, the relationship between HBEs and the Bezold-Jarisch reflex, and the new contributing factors for the occurrence of HBEs, such as stellate ganglion block or the intraoperative administration of intravenous fentanyl.

QTc interval and neurological outcomes in aneurysmal subarachnoid hemorrhage

BACKGROUND

Prolonged heart rate-corrected QT (QTc) interval is frequently observed in subarachnoid hemorrhage (SAH). This study was conducted to determine the relationship between QTc interval and neurological outcome during the acute posthemorrhagic period after aneurysmal SAH.

METHODS

We studied 71 patients undergoing surgery who were admitted within 24 h after the onset of aneurysmal SAH. Standard 12-lead electrocardiography was performed on admission (T1) and at 1 and 7 days after operation (T2 and T3). QT intervals were corrected by heart rate according to the Fridericia formula. The Glasgow Coma Scale (GCS) score was calculated over the period T1-T3. Neurological outcome was assessed using the Glasgow Outcome Scale at hospital discharge.

RESULTS

Among the 71 patients, 31 had an unfavorable neurological outcome. Although QTc interval prolongation improved in patients with a good outcome, QTc interval prolongation continued in patients with an unfavorable outcome. The areas under the receiver-operator characteristic curves showed that the QTc and GCS score at T3, and the Hunt and Hess grade were significant predictors of an unfavorable neurological outcome. The threshold value, sensitivity, and specificity for the QTc at T3 were 448 ms, 73% [95% confidence interval (CI), 68-78], and 93% (95% CI, 90-96), respectively.

CONCLUSION

This study confirms that QTc interval prolongation continues in the SAH patients with an unfavorable outcome but that QTc interval prolongation improves in patients with a good outcome, suggesting that a QTc interval of more than 448 ms at 7 days after operation is a predictor of neurological outcome after SAH.

Factors contributing to episodes of bradycardia hypotension during shoulder arthroscopic surgery in the sitting position after interscalene block

Background

Arthroscopic shoulder surgery has been performed in the sitting position under interscalene block (ISB). Bradycardia hypotension (BH) episodes have a reported incidence of 13-29% in this setting. We performed a retrospective study to investigate contributing factors to the occurrence of BH episodes.

Methods

According to BH episodes, we divided 63 patients into two groups: BH group (n = 13) and non-BH group (n = 50). Anesthetic records and block data sheets were reviewed for demographic data, intraoperative medications, sites of ISB, use of epinephrine in local anesthetics, degree of sensory blockade, and percent change of heart rate or systolic blood pressure (SBP). Statistical analysis was done using Chi square test and Student's t-test.

Results

There were no significant differences in the use of epinephrine in local anesthetics between the two groups. The location of ISB site was different between the two groups in that there were relatively more right-sided ISBs in the BH group than in the non-BH group (P = 0.048). The degree of sensory blockade was lower, but not significantly, in the C8 and T1 dermatomes of the BH group than in the non-BH group (P = 0.060 and 0.077, respectively). There was a relatively higher incidence of fentanyl supplementation in the BH group than in the non-BH group (P = 0.000).

Conclusions

These results suggest that right ISB and perioperative supplementation of fentanyl due to incomplete block are possible contributing factors to the occurrence of BH episodes in the sitting position during shoulder surgery using ISB.