Effects of unilateral stellate ganglion block on the spectral characteristics of heart rate variability

Establishment of stellate ganglion block in mice

BACKGROUND

There have been no reports on the successful implementation of stellate ganglion block (SGB) in mice.

OBJECTIVES

This study aims to investigate a new method for implementing SGB in mice by placing them in a supine position with abducted upper limbs and touching the trachea and sternoclavicular joint with the hand.

METHODS

Fifty BABL/C mice, 8-10 weeks, were selected and randomly divided into four groups: control group (n = 5); SGB-R group (n = 15); SGB-L group (n = 15); and SGB-L + R (group n = 15). SGB was administered with 0.15% ropivacaine solution in a volume of 0.1 mL. The control group received equal volumes of saline. Horner's syndrome, heart rate, and complications such as brachial plexus block, vascular injury, pneumothorax, local anesthetic toxicity, and death were observed.

RESULTS

Horner's syndrome developed in 100% of SGB surviving mice; no difference was seen in the time to onset (100.4 ± 13.4 vs 96.7 ± 12.4, mean ± SD, seconds) and duration (264.1 ± 40.5 vs 296.3 ± 48.0, mean ± SD, min) of Horner's syndrome in the left and right SGB (P > 0.05). Compared with the control group (722 [708-726], median [IQR], bpm), the heart rate was significantly slowed down in the right SGB (475 [451.5-491], median [IQR], bpm) (P < 0.05). While the heart rate was slowed down after performing the left SGB, the difference was not statistically significant (P > 0.05). The overall complication rate was 18.4%, with a brachial plexus block rate of 12.3%, a vascular injury rate of 4.6%, and a mortality rate of 1.5%, as well as no local anesthetic toxicity (includes bilateral implementation of SGB) or pneumothorax manifestations were found.

CONCLUSIONS

This method allows for the successful implementation of SGB in a mouse model.

Stellate ganglion block for the management of electrical storm: An observational study

INTRODUCTION

Electrical storm is a life-threatening emergency with a high mortality rate. When acute conventional treatment is ineffective, stellate ganglion block can help control arrhythmia by providing a visceral cervicothoracic sympathetic block. The objective of this study is to assess the effectiveness and safety of stellate ganglion block in the management of refractory arrhythmic storm.

METHOD

Follow-up of a cohort of patients with refractory electrical storm that met the criteria for performing stellate ganglion block. The block was ultrasound-guided at C6 using local anaesthetic and a steroid - left unilateral first, bilateral if no response, followed by fluoroscopy-guided radiofrequency ablation at C7 if there was a favourable response but subsequent relapse.

RESULTS

Seven patients were included. The in-hospital mortality rate was 14.29%. Four patients received unilateral and 3 bilateral stellate ganglion block. Six were ablated and 1 received an implantable cardioverter-defibrillator. Electrical storm was controlled temporarily beyond the effect of the local anaesthetic in all patients. Three patients underwent radiofrequency ablation and 2 underwent surgical thoracic sympathectomy. The only side effect was Horner's syndrome, which was observed in all cases after administering a stellate ganglion block with local anaesthetic. Two patients died after discharge and 4 are alive at the time of writing, 3 of them have not been re-admitted for ventricular events for more than 2 years.

CONCLUSION

Ultrasound-guided stellate ganglion block is an effective and safe complement to standard cardiological treatment of refractory electrical storm.

Macrophage activation in stellate ganglia contributes to lung injury-induced arrhythmogenesis in male rats

AIM

Patients suffering from acute lung injury (ALI) are at high risk of developing cardiac arrhythmias. We hypothesized that stellate ganglia (SG) neural inflammation contributes to ALI-induced arrhythmia.

METHODS

We created an ALI rat model using a single tracheal instillation of bleomycin (2.5 mg/kg), with saline as a sham control. We recorded ECGs by implanted radiotelemetry in male bleomycin and sham rats treated with and without oral minocycline (20 mg/kg/d), an anti-inflammatory drug that inhibits microglia/macrophage activation. The SG neuronal excitability was assessed by electrophysiology experiments.

RESULTS

ECG data showed that bleomycin-exposed rats exhibited significantly more spontaneous premature ventricular contractions (PVCs) from 1- to 3-week post-induction compared with sham rats, which was mitigated by chronic oral administration of minocycline. The bleomycin-exposed rats displayed a robust increase in both the number of Iba1-positive macrophages and protein expression of interferon regulatory factor 8 in the SG starting as early at 1-week post-exposure and lasted for at least 4 weeks, which was largely attenuated by minocycline. Heart rate variability analysis indicated autonomic imbalance during the first 2-week post-bleomycin, which was significantly attenuated by minocycline. Electrical stimulation of the decentralized SG triggered more PVCs in bleomycin-exposed rats than sham and bleomycin + minocycline rats. Patch-clamp data demonstrated enhanced SG neuronal excitability in the bleomycin-exposed rats, which was attenuated by minocycline. Co-culture of lipopolysaccharide (LPS)-pretreated macrophages with normal SG neurons enhanced SG neuronal excitability.

CONCLUSION

Macrophage activation in the SG contributes to arrhythmogenesis in bleomycin-induced ALI in male rats.

[Effect of ultrasound-guided right stellate ganglion block on perioperative atrial fibrillation in patients undergoing lung lobectomy: a randomized controlled trial]

OBJECTIVE

To observe the effects of preoperative right stellate ganglion block on perioperative atrial fibrillation in patients undergoing lung lobectomy.

METHODS

Two hundred patients who underwent a scheduled lobectomy were randomly divided into the S and C groups. The S group was injected with 4mL of 0.2% ropivacaine under ultrasound guidance, and the C group did not receive stellate ganglion block. The patients underwent continuous ECG monitoring, and the incidences of atrial fibrillation and other types of arrhythmias were recorded from the start of surgery to 24hours after surgery.

RESULTS

The respective incidences of atrial fibrillation in the S group and the C group were 3% and 10% (p=0.045); other atrial arrhythmias were 20% and 38% (p=0.005); and ventricular arrhythmia were 28% and 39% (p=0.09).

CONCLUSIONS

The results of the study indicated that preoperative right stellate ganglion block can effectively reduce the incidence of intraoperative and postoperative atrial fibrillation.

Stellate ganglion block and cardiac sympathetic denervation in patients with inappropriate sinus tachycardia

Background

Inappropriate sinus tachycardia (IST) remains a clinical challenge because patients often are highly symptomatic and not responsive to medical therapy.

Objective

To study the safety and efficacy of stellate ganglion (SG) block and cardiac sympathetic denervation (CSD) in patients with IST.

Methods

Twelve consecutive patients who had drug‐refractory IST (10 women) were studied. According to a prospectively initiated protocol, five patients underwent an electrophysiologic study before and after SG block (electrophysiology study group). The subsequent seven patients had ambulatory Holter monitoring before and after SG block (ambulatory group). All patients underwent SG block on the right side first, and then on the left side. Selected patients who had heart rate reduction ≥15 beats per minute (bpm) were recommended to consider CSD.

Results

The mean (SD) baseline heart rate (HR) was 106 (21) bpm. The HR significantly decreased to 93 (20) bpm (P = .02) at 10 minutes after right SG block and remained significantly slower at 97(19) bpm at 60 minutes. Left SG block reduced HR from 99 (21) to 87(16) bpm (P = .02) at 60 minutes. SG block had no significant effect on blood pressure or HR response to isoproterenol or exercise (all P > .05). Five patients underwent right (n = 4) or bilateral (n = 1) CSD. The clinical outcomes were heterogeneous: one patient had complete and two had partial symptomatic relief, and two did not have improvement.

Conclusion

SG blockade modestly reduces resting HR but has no significant effect on HR during exercise. Permanent CSD may have a modest role in alleviating symptoms in selected patients with IST.

Effects of Linearly Polarized Near-Infrared Irradiation Near the Stellate Ganglion Region on Pain and Heart Rate Variability in Patients with Neuropathic Pain

Background

Neuropathic pain associated with sympathetic overactivity can be effectively relieved by light irradiating the region near stellate ganglion (SGI), applied as an alternative to a conventional sympathetic blockade. The clinical effect of SGI on heart rate variability (HRV) and its association with pain outcomes require investigation.

Objective

This study attempted to identify the effects of SGI on pain outcomes and HRV indices and to determine the association between pain and HRV outcomes.

Design

A prospective double-blind, randomized study.

Setting

An outpatient pain medicine clinic.

Subjects and Methods

A total of 44 patients were enrolled and randomized into the experimental group ( n = 22) and control group ( n = 22). The experimental group received 12 sessions (twice weekly) of standard SGI, whereas the control group received the same protocol with sham irradiation. Pain and HRV were measured before and after each irradiation session. All outcome measures used in the first- and second-half treatment courses were analyzed.

Results

Pain and HRV outcome measures of the experimental group significantly improved after SGI when compared with the control group in both courses. Considering time and frequency domains, the changes in HRV in the second-half treatment course exceeded those in the first-half treatment course. Pain was significantly associated with postirradiated HRV indices ( P < 0.001).

Conclusions

Twelve sessions of SGI exerted time-dependent positive effects on pain and sympathovagal imbalance. HRV outcomes, including time and frequency domains, were an independent indicator of the clinical efficiency of SGI for treating pain in patients with neuropathic pain.

Effect of thoracic epidural anesthesia on heart rate variability in a porcine model

Heart rate variability (HRV) is increasingly recognized as a means of evaluating autonomic tone. Thoracic epidural anesthesia (TEA) has been previously demonstrated to suppress the electrical storms in patients. However, the effect of TEA on HRV during sympathoexcitation remains unknown. In this study, we aimed to determine the effects of TEA on HRV response to left stellate ganglion stimulation (LSS) in a porcine model. In 12 anesthetized pigs after insertion of an epidural catheter to T1 level, a median sternotomy was performed to expose the heart and the left stellate ganglion. A 56‐electrode sock was used for obtaining epicardial activation recovery interval (ARI). Animal received LSS at 4 Hz for 30 sec. After 30 min of bupivacaine epidural injection, LSS was performed in the same way as the baseline condition. LSS significantly increased low‐frequency normalized units (LF: 44.9 ± 6.7 vs. 13.6 ± 3.1 msec² baseline, P < 0.05) and decreased high‐frequency normalized units (HF: 11.5 ± 4.6 vs. 41.9 ± 5.1 msec² baseline, P < 0.05). As a result, LF/HF significantly increased from 0.3 ± 0.2 to 3.9 ± 1.4 during LSS. TEA significantly attenuated the LF/HF from 3.9 ± 1.4 to 1.6 ± 0.8 with increased HF components from 11.5 ± 4.6 to 26.5 ± 3.2 msec². LF component significantly correlates with global ARI (r = −0.81) and dispersion of repolarization (r = 0.85). HRV can precisely reflect the cardiac autonomic tone and TEA modulates the HRV by enhancing the HF components probably through a parasympathetic nerve system.

Acute effects of unilateral temporary stellate ganglion block on human atrial electrophysiological properties and atrial fibrillation inducibility

BACKGROUND

In experimental models, stellate ganglion block (SGB) reduces the induction of atrial fibrillation (AF), while data in humans are limited.

OBJECTIVE

The aim of this study was to assess the effect of unilateral SGB on atrial electrophysiological properties and AF induction in patients with paroxysmal AF.

METHODS

Thirty-six patients with paroxysmal AF were randomized in a 2:1 order to temporary, transcutaneous, pharmaceutical SGB with lidocaine or placebo before pulmonary vein isolation. Lidocaine was 1:1 randomly infused to the right or left ganglion. Before and after randomization, atrial effective refractory period (ERP) of each atrium, difference between right and left atrial ERP, intra- and interatrial conduction time, AF inducibility, and AF duration were assessed.

RESULTS

After SGB, right atrial ERP was prolonged from a median (1st-3rd quartile) of 240 (220-268) ms to 260 (240-300) ms (P < .01) and left atrial ERP from 235 (220-260) ms to 245 (240-280) ms (P < .01). AF was induced by atrial pacing in all 24 patients before SGB, but only in 13 patients (54%) after the intervention (P < .01). AF duration was shorter after SGB: 1.5 (0.0-5.8) minutes from 5.5 (3.0-12.0) minutes (P < .01). Intra- and interatrial conduction time was not significantly prolonged. No significant differences were observed between right and left SGB. No changes were observed in the placebo group.

CONCLUSION

Unilateral temporary SGB prolonged atrial ERP, reduced AF inducibility, and decreased AF duration. An equivalent effect of right and left SGB on both atria was observed. These findings may have a clinical implication in the prevention of drug refractory and postsurgery AF and deserve further clinical investigation.

Effects of ultrasound-guided stellate ganglion block on autonomic nervous function during CO2-pneumoperitoneum: A randomized double-blind control trial

BACKGROUND

CO2-pneumoperitoneum can cause sympathetic nerve activity increased and is likely to causes severe stress-related homeostatic disorders.

OBJECTIVE

Patients undergoing elective laparoscopic cholecystectomy were administered type-B ultrasound-guided stellate ganglion block (SGB) to observe the effects on autonomic nervous system during CO2- pneumoperitoneum.

DESIGN

A randomized, double-blinded, and placebo-controlled study.

SETTING

University-affiliated teaching hospital.

PATIENTS

Eighty patients (aged 32-75 years; weight, 45-80 kg; American Society of Anesthesiologists (ASA) physical status classification, class I or II) undergoing elective laparoscopic cholecystectomy.

INTERVENTIONS

The RSGB group was administered lidocaine 1% 7 ml under ultrasound guidance.

MAIN OUTCOME MEASURES

The low frequency (LF), high frequency (HF), total power (TP) and LF/HF ratio were recorded before the block (T0), 5 min (T1) and 30 min (T2) following pneumoperitoneum, 5 min after deflation of pneumoperitoneum (T3) and after surgery (T4). The low-frequency normalized unit (LFnu) and high-frequency normalized units (HFnu) were calculated.

RESULTS

Compared with T0, LF, LFnu and LF/HF ratio were significantly elevated at T1-4 (all P< .05 or .01). HFnu was significantly decreased at T2-4 in control group (P< .05) while HF was significantly elevated (P< .01). The LF/HF ratio was significantly decreased (P< .05) at T1-4 in RSGB group. Compared with control group, the LF, LFnu and LF/HF ratio were significantly decreased (P< .05) and HF and HFnu was significantly elevated (P< .05 or .01) at T1-4 in RSGB group.

CONCLUSION

Ultrasound-guided RSGB inhibited CO2-pneumoperitoneum-induced sympathetic neural excitation, upregulated vagal nerve stimulation and maintained stable autonomic nervous function.

Effects on hemodynamic variables and echocardiographic parameters after a stellate ganglion block in 15 healthy volunteers

BACKGROUND

The sympathetic nervous system has an important role in generating pain. Various pathomechanisms are involved that respond well to the application of local anesthetics (LA), for example to the stellate ganglion block (SGB).

OBJECTIVES

We wanted to know more about the effects of SGB on cardiovascular parameters.

METHODS

We included 15 healthy volunteers; another 15 healthy volunteers as a control group (sham injection of LA). In order to produce a more precise SGB, we employed only a small volume of LA (3mL), a LA with a lower permeability (procaine 1%), and a modified injection technique. Systolic and diastolic blood pressure (SBP, DBP), heart rate (HR), and echocardiographic parameters were recorded before and after SGB. We also investigated whether there are side differences (left and right SBG).

RESULTS

At baseline all parameters were within the normal range. After performing right and left SGB DBP significantly increased (on the right side from 68.73±8.61 to 73.53±11.10, p=0.015; on the left side from 70.66±13.01 to 77.93±10.40, p=0.003). In the control group no increase in DBP was observed. No side-specific differences were found, except a significant reduction in the maximum velocity of myocardial contraction during the systole with left-sided SGB.

CONCLUSIONS

Even with our methods we could not prevent the simultaneous occurrence of a partial parasympatholytic effect. For this reason, the SGB has only minor hemodynamic effects, which is desirable as it enhances the safety of the SGB.

Maladaptive autonomic regulation in PTSD accelerates physiological aging

A core manifestation of post-traumatic stress disorder (PTSD) is a disconnection between physiological state and psychological or behavioral processes necessary to adequately respond to environmental demands. Patients with PTSD experience abnormal oscillations in autonomic states supporting either fight and flight behaviors or withdrawal, immobilization, and dissociation without an intervening “calm” state that would provide opportunities for positive social interactions. This defensive autonomic disposition is adaptive in dangerous and life threatening situations, but in the context of every-day life may lead to significant psychosocial distress and deteriorating social relationships. The perpetuation of these maladaptive autonomic responses may contribute to the development of comorbid mental health issues such as depression, loneliness, and hostility that further modify the nature of cardiovascular behavior in the context of internal and external stressors. Over time, changes in autonomic, endocrine, and immune function contribute to deteriorating health, which is potently expressed in brain dysfunction and cardiovascular disease. In this theoretical review paper, we present an overview of the literature on the chronic health effects of PTSD. We discuss the brain networks underlying PTSD in the context of autonomic efferent and afferent contributions and how disruption of these networks leads to poor health outcomes. Finally, we discuss treatment approaches based on our theoretical model of PTSD.

Effects of stellate ganglion block on cardiovascular reaction and heart rate variability in elderly patients during anesthesia induction and endotracheal intubation

STUDY OBJECTIVE

To investigate the effects of stellate ganglion block (SGB) on cardiovascular response and heart rate (HR) variability in elderly patients during anesthesia induction and endotracheal intubation.

DESIGN

A randomized, double-blinded, and placebo-controlled study.

SETTING

University-affiliated teaching hospital.

PARTICIPANTS

Eighty elderly patients (American Society of Anesthesiologists grades I and II) receiving elective surgery during general anesthesia.

INTERVENTIONS

Right stellate ganglion injection (SGB) was performed in all patients using 10 mL of 1% lidocaine or normal saline.

MEASUREMENTS

Systolic blood pressure (BP), diastolic BP, HR, and calculated rate pressure product. HR variability at the following time points: conscious status before induction (T0); immediately before intubation (T1); immediately after intubation (T2); and 1, 3, and 5 minutes postintubation (T3, T4, and T5).

MAIN RESULTS

No significant differences in BP and HR were observed between the 2 groups. Rate pressure product values significantly increased in the control group compared with baseline and SGB group values. Low-frequency power (LF) and LF/high-frequency power (HF) significantly increased, and HF and normalized units of HF significantly decreased in the control group compared with baseline values. LF, normalized units of LF, and LF/HF in the SGB group significantly decreased compared with those of the control group.

CONCLUSION

SGB protects the myocardium and effectively suppresses stress responses during anesthesia induction and tracheal intubation in elderly patients.

Regional changes in cardiac and stellate ganglion norepinephrine transporter in DOCA-salt hypertension

Uptake of norepinephrine via the neuronal norepinephrine transporter is reduced in the heart during deoxycorticosterone (DOCA)-salt hypertension. We hypothesized that this was due to reduced norepinephrine transporter mRNA and/or protein expression in the stellate ganglia and heart. After 4 weeks of DOCA-salt treatment there was no change in norepinephrine transporter mRNA in either the right or the left stellate ganglia from hypertensive rats (n=5-7, p>0.05). Norepinephrine transporter immunoreactivity in the left stellate ganglion was significantly increased (n=4, p<0.05) while the right stellate ganglion was unchanged (n=4, p>0.05). Whole heart norepinephrine content was significantly reduced in DOCA rats consistent with reduced uptake function; however, when norepinephrine was assessed by chamber, a significant decrease was noted only in the right atrium and right ventricle (n=6, p<0.05). Cardiac norepinephrine transport binding by chamber revealed that it was only reduced in the left atrium (n=5-7, p>0.05). Therefore, 1) contrary to our hypothesis reduced reuptake in the hypertensive heart is not exclusively due to an overall reduction in norepinephrine transporter mRNA or protein in the stellate ganglion or heart, and 2) norepinephrine transporter regulation occurs regionally in the heart and stellate ganglion in the hypertensive rat heart.

Effect of interscalene brachial plexus block on heart rate variability

Background

Interscalene brachial plexus block (ISB) may be followed by cardiovascular instability. Until date, there is no clear picture available about the underlying mechanisms of ISB. In this study, we aimed to determine the changes in heart rate variability (HRV) parameters after ISB and the differences between right- and left-sided ISBs.

Methods

We prospectively studied 24 patients operated for shoulder surgery in sitting position and divided them into two respective groups: R (right-sided block = 14 pts) and L (left-sided block = 10 pts). HRV data were taken before and 30 min after the block. Ropivacaine without ephedrine was used for the ISB through an insulated block needle connected to a nerve stimulator. Statistical analysis implemented chi-square, Student's and t-paired tests. Skewed distributions were analyzed after logarithmic transformation.

Results

All the studied patients had successful blocks. Horner's syndrome signs were observed in 33.3% of the patients (R = 5/14, L = 3/10; [P = 0.769]). There were no significant differences in pre-block HRV between the groups. The application of ISB had differential effect on HRV variables: R-blocks increased QRS and QTc durations and InPNN50, while a statistical decrease was seen in InLF. L-blocks did not show any significant changes. These changes indicate a reduced sympathetic and an increased parasympathetic influence on the heart's autonomic flow after R-block.

Conclusions

Based on the obtained results we conclude that ISB, possibly through extension of block to the ipsilateral stellate ganglion, alters the autonomic outflow to the central circulatory system in a way depending on the block's side.

Anesthetic management of patient with hypertrophic cardiomyopathy and automatic implantable cardioverter defibrillator with a hand fracture

A 26-year-old male with a history of hypertrophic cardiomyopathy (HCM) and ventricular arrhythmias s/p automatic implantable cardioverter defibrillator (AICD) placement presented for open reduction and internal fixation of an open third metacarpal fracture and extensor tendon repair. He underwent successful surgery after placement of an ultrasound-guided infraclavicular brachial plexus block with ropivacaine 0.5% as the main anesthetic. This case report discusses the anesthetic management of patients with HCM and AICD, different approaches available for brachial plexus blockade, and potential complications of anesthesia and surgery in this group of patients.

Stellate ganglion block: a therapeutic alternative for patients with medically refractory inappropriate sinus tachycardia?

Inappropriate sinus tachycardia (IST) is a clinical syndrome characterized by presence of non-paroxysmal tachyarrhythmia manifesting with increased resting heart rate and exaggerated or persistent response to exercise or position. When IST is intolerable and medically refractory, invasive therapies such as sinus node modification or atrioventricular node ablation with placement of permanent pacemaker are tried to control symptoms. We present a 34 year old patient with symptomatic IST unresponsive to medical therapy who underwent anesthetic block of the right and left stellate ganglia. At four month follow up the patient demonstrated sustained improvement in heart rate and reported freedom from previous symptoms.

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.

Comparison of 2% mepivacaine, clipping, and radiofrequency thermocoagulation for duration and magnitude of action in peripheral arterial blood flow induced by sympathetic block in anesthetized dogs

BACKGROUND AND OBJECTIVES

Thoracic sympathetic block has recently been performed by placement of the clips on the sympathetic chain to interrupt nerve conduction. The aim of this study was to compare clipping with 2% mepivacaine and radiofrequency thermocoagulation for the potency of sympathetic block from the results of the duration and magnitude of the vasodilation effect induced by thoracic sympathetic block in dogs.

METHODS

We measured mean arterial pressure, heart rate, and right and left brachial artery blood flow (BABF) before and after thoracic sympathetic block in 24 dogs. The experimental protocol was designed as follows: (1) left thoracic sympathetic block by 1.0 mL of 2% mepivacaine (n = 8), (2) left thoracic sympathetic block by clipping (n = 8), and (3) left thoracic sympathetic block by radiofrequency thermocoagulation (n = 8).

RESULTS

Mean arterial pressure and heart rate did not change significantly throughout the study in either group. Left thoracic sympathetic block by 2% mepivacaine increased left BABF significantly from 5 to 70 mins after the block (baseline, 100%; peak at 10 mins after the block, 179% ± 33%; P < 0.01). Left thoracic sympathetic block by clipping increased left BABF significantly from 5 to 120 mins after the block (baseline, 100%; peak at 30 mins after the block, 156% ± 31%; P < 0.01). Left thoracic sympathetic block by radiofrequency thermocoagulation increased left BABF significantly from 5 to 120 mins after the block (baseline, 100%; peak at 10 mins after the block, 206% ± 31%; P < 0.01).

CONCLUSIONS

Clipping may have a same potency compared with 2% mepivacaine and a less potency compared with radiofrequency thermocoagulation in thoracic sympathetic block in dogs.

Comparison of bupivacaine, ropivacaine, and levobupivacaine in an equal dose and concentration for sympathetic block in dogs

BACKGROUND AND OBJECTIVES

The aim of this study was to compare the potency of bupivacaine, ropivacaine, and levobupivacaine in an equal dose and concentration for sympathetic block.

METHODS

We measured mean arterial pressure, heart rate (HR), and right and left brachial artery blood flow (BABF) before and after cervicothoracic sympathetic block in 24 dogs. The experimental protocol was designed as follows: (1) left cervicothoracic sympathetic block with 1.0 mL of 0.25% bupivacaine (n = 8), (2) left cervicothoracic sympathetic block with 1.0 mL of 0.25% ropivacaine (n = 8), and (3) left cervicothoracic sympathetic block with 1.0 mL of 0.25% levobupivacaine (n = 8).

RESULTS

Mean arterial pressure and heart rate did not change significantly throughout the study in either group. Left cervicothoracic sympathetic block with 0.25% bupivacaine increased left BABF significantly from 5 to 100 mins after the block (baseline, 100%; peak at 20 mins after the block, 218% +/- 48%; P < 0.01). Left cervicothoracic sympathetic block with 0.25% ropivacaine increased left BABF significantly from 5 to 100 mins after the block (baseline, 100%; peak at 10 mins after the block, 254 +/- 38%; P < 0.01). Left cervicothoracic sympathetic block with 0.25% levobupivacaine increased left BABF significantly from 5 to 80 mins after the block (baseline, 100%; peak at 20 mins after the block, 183% +/- 38%; P < 0.01).

CONCLUSIONS

Ropivacaine may induce a greater increase in vasodilation than bupivacaine and levobupivacaine at the same dose and concentration for sympathetic block in dogs.

The changes of heart rate variability after unilateral stellate ganglion block

Background

The effect of the unilateral stellate ganglion block (SGB) on cardiovascular regulation remains controversial. We wished to evaluate the changes in heart rate variability (HRV) after a unilateral stellate ganglion block in patients with head and neck pain in the present study.

Methods

Patients with head and neck pain (n = 89) were studied. HRV was determined before and after a C6 unilateral stellate ganglion block (right-sided SGB, 40; left-sided SGB, 49) using a paratracheal technique with 1% mepivacaine (6 ml).

Results

There were no significant differences in HRV indices before and after right-sided SGB. The log scale of power in the high frequency range (lnHF) was increased and ratio of power in the low frequency range (LF) to power in the high frequency range (HF) ratio was decreased after left-sided SGB.

Conclusions

These results demonstrated that left-sided SGB increased parasympathetic activities in patients with head and neck pain.

Effects of bilateral stellate ganglion block on autonomic cardiovascular regulation

BACKGROUND

Stellate ganglion block (SGB) is performed for the diagnosis and treatment of sympathetic dependent pain in the head, neck and upper limbs. However, the effects of bilateral SGB on cardiovascular and autonomic regulation remain unknown. The aim of this study was to assess the effects of bilateral SGB on cardiovascular and autonomic function by measuring heart rate variability (HRV), systolic blood pressure variability (SBPV) and spontaneous baroreflex sensitivity (SBRS).

METHODS AND RESULTS

Twenty healthy volunteers were randomly allocated to receive right or left SGB with 8 ml 1% lidocaine solution; after 20 min, the contralateral side SGB was performed. Changes in the RR interval (RRI), systolic blood pressure (SBP), HRV, SBPV and SBRS were assessed before and after bilateral SGB. The low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.4 Hz) components of HRV and SBRS decreased significantly; however, no significant changes were found in RRI, SBP and the LF and HF components of SBPV after bilateral SGB. In subjects with symptoms of vagal blockade, HRV, SBP and SBRS were significantly affected by bilateral SGB.

CONCLUSIONS

Bilateral SGB should be performed cautiously because it can reduce cardiac vagal modulation and BRS, especially for those with symptoms of vagal blockade after bilateral SGB.

Evaluation of PR, RR, QT intervals and QT dispersion following stellate ganglion block in chronic shoulder-hand pain patients

Right stellate ganglion block (SGB) can increase QT interval, rate-corrected QT interval (QTc), QT dispersion (QTD), rate-corrected QTD (QTcD), and RR interval while left SGB can decrease these intervals in healthy volunteers. No such studies have been conducted in patients with chronic pain, hence this study was designed to investigate the effects of left and right SGB on these variables in chronic shoulder-hand pain patients. In this study, 28 patients with chronic shoulder-hand pain of at least 6 months duration were given right or left SGB depending on the shoulder affected. A 12-lead electrocardiogram (ECG) was recorded before the block, 30 minutes and 60 minutes after the block. PR interval, RR interval, QT interval were recorded in all 12 leads while QTc, QTD, and QTcD were calculated. Right SGB was performed in 21 patients. A significant decrease (P < 0.05) in PR interval and a significant increase (P < 0.05) in RR interval, QT interval, and QTc interval were observed. QTD showed a significant increase (P < 0.05) only at 30 minutes after right SGB. Left SGB was performed in seven patients. A significant decrease (P < 0.05) in QT interval was observed throughout the study period, while QTc showed a significant decrease (P < 0.05) only at 60 minutes after the block. We conclude that right SGB induces significant increase of QT interval, RR interval, QTc interval, QTD, and a significant decrease of PR interval while left SGB produces a significant decrease in QT and QTc intervals in patients with chronic shoulder-hand pain.

A novel technique for experimental stellate ganglion block in rats

A stellate ganglion block (SGB) is routinely performed in a clinical setting for the treatment of sympathetically maintained pain syndromes. However, the cardiovascular effects of SGB have not been well defined. The purpose of the present study was to develop a new technique of SGB in a rat model. Our new technique of SGB is a posterior percutaneous approach and uses the cartilaginous process of the C7 spinous process as a landmark. Twenty-six Sprague-Dawley female rats were divided into six groups. Group I (n = 4) underwent right sided SGB, Group II (n = 5) underwent left-sided SGB, and Group III (n = 5) underwent bilateral SGB using bupivacaine 0.25%. Three additional sham groups (n = 4 in each group) served as controls to each of the three treatment groups. Ipsilateral eyelid droop (ptosis) was observed in all animals that underwent SGB with bupivacaine. Heart rate decreased significantly for up to 45 min after bilateral SGB compared with control groups. However, this value did not change in rats after unilateral SGB. In 9 additional rats, we evaluated the accuracy of SGB by injecting methylene blue to stain the right (n = 3), left (n = 3), and bilateral SGB (n = 3). At autopsy, 11 of 12 SG were stained post-methylene blue injection. We conclude from our study that our new approach, posterior percutaneous SGB is a reliable technique that can be used for further studies.

IMPLICATIONS

We describe a new technique for stellate ganglion block in rats that may be used in future studies to investigate the role of cervical sympathetic nervous system (especially the stellate ganglion) in regulating sympathetically maintained pain and myocardial function.

The effects of therapeutic ultrasound on heart rate variability: a placebo controlled trial

The effect of therapeutic ultrasound (US) on nervous system is controversial and the effect on autonomic nervous system is not clear. Therefore, the present placebo-controlled trial was planned to investigate the effects of therapeutic US application on right-side stellate ganglion, by using analysis of heart rate variability (HRV). A total 12 healthy volunteers were included in the study. RR intervals were recorded for 5 min before and after the US application, in supine and sitting positions. All procedures were repeated in all participants with sham US one week later. The heart rate (HR) was obtained by time-domain analysis and low frequency (LF) power (%), high frequency (HF) power (%) and LF/HF ratio values were obtained by frequency-domain (power spectral density) analysis. After the US application, there was a decrease in the HR (p = 0.002) and the HF power (%) component (p = 0.015) in supine position and a decrease in HR (p = 0.002) and LF/HF ratio (p = 0.028) in sitting position. There was no significant difference after the sham US application. In conclusion, we observed that therapeutic US application on stellate ganglion causes alterations on HRV parameters.

An Unusual Complication of Sinus Arrest Following Right-Sided Stellate Ganglion Block: A Case Report

We present a case of a 29-year-old female patient who had presented to us for the management of her chronic right shoulder-hand pain and developed a sinus arrest following a right-sided stellate ganglion block (RSGB). This patient on receiving a diagnostic RSGB via the anterior paratracheal (C6) approach developed sinus arrest followed by apnea and unconsciousness. On institution of resuscitative measures involving tracheal intubation, positive pressure ventilation, cardiac massage, and intravenous atropine, spontaneous cardiac activity recovered in about 3 minutes. Other signs and symptoms resolved fully in a total of 10 minutes. She had persistent postural hypotension lasting for about 24 hours requiring bed rest and was discharged about 36 hours after the procedure, without any adverse sequelae. As the sinus node is supplied by the right-sided sympathetic chain, its blockade probably resulted in unopposed parasympathetic activity leading to asystole. Available evidence of the role of right stellate ganglion in regulation of cardiac electrophysiology and functioning is also discussed.

Preoperative stellate ganglion blockade prevents tourniquet-induced hypertension during general anesthesia

BACKGROUND

Prolonged and excessive inflation of pneumatic tourniquets leads to a hyperdynamic circulatory response. Sympathomimetic activity is an important factor in tourniquet-induced hypertension. Stellate ganglion block specifically blunts sympathetic efferent nerves and prevents hypertension induced by sympathomimetic stimulation. The present study was performed to investigate the effects of stellate ganglion block (SGB) on arterial pressure and heart rate during prolonged tourniquet use under general anesthesia.

METHODS

Twenty patients scheduled for knee arthroscopy were either treated with 10 ml of 1% lidocaine for SGB (SGB group; n = 10), or intramuscular injection (IM group; n = 10) before tourniquet inflation. Comparisons of systolic and diastolic arterial pressure and heart rate were made before and after the induction of anesthesia, 10 min after the lidocaine treatment, every 5 min during the first 60 min after tourniquet inflation, and immediately before and 5 min following deflation. The maximum values of the circulatory variables were compared.

RESULTS

Tourniquet inflation caused increases in the circulatory variables in both groups. Systolic arterial pressure in the SGB group was significantly lower than that in the IM group after 55 min of tourniquet inflation. Diastolic arterial pressure also was significantly lower in the SGB group immediately before the deflation. The maximum values of the three hemodynamic variables were significantly lower in the SGB group. Arterial pressure significantly decreased after tourniquet deflation in the IM group.

CONCLUSION

Ipsilateral SGB attenuated the hyperdynamic response mediated by prolonged tourniquet inflation during knee arthroscopy.

Holter changes resulting from right-sided and bilateral infrastellate upper thoracic sympathectomy

BACKGROUND

We tested the hypothesis that no right-sided dominance exists after infrastellate surgical upper-thoracic sympathectomy. We aimed to confirm whether a significant bradycardia was constant and only dependent on the right side.

METHODS

We performed 24-hour Holter electrocardiographic recordings in 12 patients referred for bilateral sympathectomy. Surgery was performed at two distinct times allowing for the study of the consequences of unilateral right and bilateral sympathectomy.

RESULTS

Heart rate was 77 +/- 8 beats per minute before surgery on the 24-hour recording and significantly decreased after bilateral (67.8 +/- 6.5 beats per minute; p < 0.05) but not after unilateral right sympathectomy. Consistently spectral analysis variables significantly changed after bilateral surgery but showed no right-sided dominance. Little effect of sympathectomy was found on the QT interval, which tended to decrease after bilateral sympathectomy.

CONCLUSIONS

Patients should be informed of the bradycardia resulting from sympathectomy. No right-sided dominance can be found consistently with the random distribution of substellate cardiac fibers reported in anatomic studies.

Effects of right stellate ganglion block on the autonomic nervous function of the heart: a study using the head-up tilt test

The effect of peripheral sympathetic block on the autonomic nerve function of the heart was studied using the head-up tilt test (HUTT) and right stellate ganglion block (RSGB). Blood pressure (BP), heart rate (HR) and the parameters of power spectral analysis of HR variability recorded during the HUTT were measured in 8 patients with chronic pain syndrome before and after RSGB. In the control state, the mean HR and the LF/HF component recorded during HUTT significantly increased whereas the HF component markedly decreased. Conversely, the mean HR and LF/HF and HF components during HUTT did not significantly alter after the RSGB procedure. There were no significant differences between the BP values before and after RSGB. These results suggest that RSGB suppresses cardiac sympathetic function without significantly affecting BP and thus may be a safe and effective therapy for the chronic pain syndrome.

Spontaneous onset of torsade de pointes in long-QT syndrome and the role of sympathovagal imbalance

The net effects of sympathetic and vagal activity on the QT interval and the mode of spontaneous onset of torsade de pointes (TdP) are still unclear in long-QT syndrome. Two patients with long-QT syndrome had syncope while undergoing Holter ECG investigation. The spontaneous onset of TdP in these patients was analyzed with respect to the relation between the RR and QT intervals. Both patients were high-school students (16- and 17-year-old boys) who had been diagnosed as long-QT syndrome and followed up without medical treatment because they had had neither a history of syncope nor arrhythmia induction by treadmill exercise tests. The first episode of syncope in both patients occurred during ordinary daily life and was not related to exercise or psychological stress. The dynamic changes between the RR and QT intervals associated with the spontaneous onset of TdP were analyzed by Holter ECG. Both patients showed sinus tachycardia followed by abrupt sinus bradycardia immediately before the onset of TdP. The enhanced rate of the adaptive response of the QT interval that occurred during the deceleration of the heart rate preceded the onset of TdP. These observations suggest that the complex situation that follows sympathovagal imbalance may have an important role in the dynamic change in the QT interval and initiation of TdP in patients with long-QT syndrome.