The effects of unilateral stellate ganglion blockade on human cardiac function during rest and exercise

Impact of Neurons on Patient-Derived Cardiomyocytes Using Organ-On-A-Chip and iPSC Biotechnologies

In the heart, cardiac function is regulated by the autonomic nervous system (ANS) that extends through the myocardium and establishes junctions at the sinus node and ventricular levels. Thus, an increase or decrease in neuronal activity acutely affects myocardial function and chronically affects its structure through remodeling processes. The neuro-cardiac junction (NCJ), which is the major structure of this system, is poorly understood and only a few cell models allow us to study it. Here, we present an innovant neuro-cardiac organ-on-chip model to study this structure to better understand the mechanisms involved in the establishment of NCJ. To create such a system, we used microfluidic devices composed of two separate cell culture compartments interconnected by asymmetric microchannels. Rat PC12 cells were differentiated to recapitulate the characteristics of sympathetic neurons, and cultivated with cardiomyocytes derived from human induced pluripotent stem cells (hiPSC). We confirmed the presence of a specialized structure between the two cell types that allows neuromodulation and observed that the neuronal stimulation impacts the excitation-contraction coupling properties including the intracellular calcium handling. Finally, we also co-cultivated human neurons (hiPSC-NRs) with human cardiomyocytes (hiPSC-CMs), both obtained from the same hiPSC line. Hence, we have developed a neuro-cardiac compartmentalized in vitro model system that allows us to recapitulate the structural and functional properties of the neuro-cardiac junction and that can also be used to better understand the interaction between the heart and brain in humans, as well as to evaluate the impact of drugs on a reconstructed human neuro-cardiac system.

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.

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.

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.

Differential effects of right versus left stellate ganglion block on left ventricular function in humans: an echocardiographic analysis

STUDY OBJECTIVES

To evaluate the effects of unilateral stellate ganglion blockade on left ventricular function.

DESIGN

Prospective cohort of patients with chronic regional pain syndrome type I and II of the upper extremity requiring therapeutic stellate ganglion blockade.

SETTING

University-affiliated hospital.

PATIENTS

Fifteen adult ASA physical status I and II patients with the diagnosis of chronic regional pain syndrome type I and II of the arm were studied. Right stellate ganglion block was performed in nine subjects and a left in six.

INTERVENTIONS

Stellate ganglion block was performed with 10 mL of 1% plain Xylocaine. Transthoracic echocardiograms were performed immediately prior and 30 min following the block.

MEASUREMENTS

Heart rate and blood pressure were monitored at regular intervals. Global systolic function was determined by calculating ejection fraction. Regional systolic motion was evaluated on the short axis and four-chamber views using the American Society of Echocardiography criteria. Diastolic function was assessed with pulsed-wave Doppler of the left ventricular outflow tract and the mitral valve. Data collected included isovolumic relaxation time and early and atrial velocity patterns.

MAIN RESULTS

A successful stellate ganglion block was achieved in all patients. Blood pressure and heart rate were not significantly different during data collection. Patients who underwent a right stellate ganglion block showed no significant differences in systolic or diastolic function. Following a left stellate ganglion block, global and regional systolic function remained unchanged. Isovolumic relaxation time was increased but did not reach statistical significance (80 +/- 13 ms to 88 +/- 9 ms; p = 0.09). Left ventricular end-diastolic (LVEDV) and end-systolic volumes (LVESV) were significantly increased (LVEDV from 73 +/- 9 mL to 100 +/- 9 mL, p < 0.02; LVESV from 31 +/- 4 mL to 37 +/- 4 mL, p < 0.03).

CONCLUSIONS

In patients without cardiovascular disease, unilateral denervation of the left ventricle after stellate ganglion block produces no clinical deleterious effects on left ventricular function.

Haemodynamic effects of a left stellate ganglion block in ASA I patients. An echocardiographic study

In anaesthetized dogs, stellate ganglion blockade led to a moderate disturbance in left ventricular diastolic function. We investigated the effect of a left-sided block, following injection of 10 mL bupivacaine 0.5%, on echocardiographic variables of ventricular function in eight otherwise healthy patients with sympathetically mediated pain syndromes. After the blockade, heart rate (control: 66+/-3 (mean+/- SEM), block: 64+/-3 min-1) and mean arterial blood pressure (88.5+/-6.0 vs. 84.0+/-8.1 mmHg) were unchanged, but afterload decreased (end-systolic meridional wall stress; 69.6+/-9.9 vs. 59.8+/-7.1, P < 0.05). Stroke volume increased from 71.2+/-8.1 to 79.6+/-7.4 mL, P < 0.05. Variables of systolic function were unchanged, but relaxation was prolonged (isovolumic relaxation time; 71+/-5 vs. 81+/-4 ms, P < 0.05). In patients who were ASA I, there was a small impairment in echocardiographic variables during ventricular relaxation after a left stellate ganglion blockade. This small effect did not compromise ventricular function, and the heart responded with a small stroke volume increase to the simultaneous afterload reduction.

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

The effect of unilateral stellate ganglion block on cardiovascular regulation remains controversial, so the present study used power spectral analysis of heart rate variability to investigate its effect on the autonomic neural control of the heart. In 20 young healthy volunteers (mean age: 25 years), heart rate variability was determined before and after unilateral stellate ganglion block (right side 11, left side 9) using 8 ml of 1% mepivacaine during supine rest. Using autoregressive spectrum analysis, power spectra were quantified by measuring the area in 3 frequency bands: high-frequency power (lnHF, parasympathetic influence) from 0.15 to 0.40 Hz, low-frequency power (lnLF, predominantly sympathetic influence) from 0.04 to 0.15 Hz, and total-frequency power (lnTF) less than 0.40 Hz. Right stellate ganglion block decreased not only the lnLF component from 6.55+/-0.84 to 5.77+/-0.47 but also the lnHF component from 4.40+/-0.95 to 3.42+/-1.12 (p<0.05). In contrast, left stellate ganglion block changed neither the lnLF nor the lnHF component. The lnTF component was also decreased significantly by right stellate ganglion block from 7.80+/-0.95 to 7.01+/-0.36 (p<0.05), but was unchanged following left stellate ganglion block. Neither right nor left stellate ganglion block induced any significant change in both the RR and corrected QT intervals. However, changes in the RR interval induced by right stellate ganglion block showed significant positive correlation with changes in lnHF (p<0.005) and lnTF (p<0.05). These results suggest that (1) autonomic innervation to the sinus node is mainly through the right-sided stellate ganglion, (2) pharmacological right-sided stellate ganglion block may attenuate not only sympathetic but also parasympathetic activity and (3) following right stellate ganglion block the decrease in both the sympathetic and parasympathetic influence on the sinus node may inconsistently counterbalance and change the RR interval.

Long QTc and torsades de pointes in human immunodeficiency virus disease

Three patients with human immunodeficiency virus (HIV) infection presented with QT, prolongation (> 440 ms) and torsades de pointes. We sought to evaluate the etiology of the long QT syndrome in these patients without previously identified causes for QT, prolongation, and determine the prevalence among patients with HIV infection. The three index patients underwent: (1) left stellate ganglion block; (2) beta-blocker challenge; and (3) electrocardiographic stress testing. QTc interval was measured before and after intervention. We undertook a retrospective analysis of prevalence of QTC prolongation among all patients with computerized ECGs over a 6-month period at one institution and compared it to the prevalence in hospitalized patients with HIV disease. Thirty-four thousand one hundred eighty-one patients with computerized ECGs were screened for QTc prolongation. Forty-two hospitalized patients with HI disease had computerized ECG during the same 6-month period. In the three index patients, the QTc failed to shorten with left stellate ganglion blockade, beta-blocker challenge, or stress testing, suggesting an acquired form of the long QT syndrome in these patients with HIV disease. None had previously recognized acquired causes of QT, prolongation. Mexiletine hydrochloride was useful in preventing recurrences of torsades de pointes. We observed a 7.0% prevalence of QT, prolongation among all patients screened. Hospitalized patients with HIV disease (n = 42) during this same period, demonstrated an increased prevalence of QT, prolongation (28.6%, P = 0.002). Patients with HIV disease have a significantly higher prevalence of QTc prolongation than a general hospital-based population, may have an unrecognized acquired form of the long QT syndrome, and are at risk for torsades de pointes.