Bezold Jarisch Research Articles

Post-Exercise Syncope in a Previously Healthy 67-Year-Old Man: The Bezold–Jarisch Reflex and the Role of Autonomic Nervous System Dysfunction

A 67-year-old man started treatment due to frequent asymptomatic premature ventricular complexes (PVCs) accidentally being registered during a preventive examination by a specialist, because of which he was referred to cardiologist. During the initial 24-hour (h) ECG monitoring, 4.5% PVCs and one episode of asymptomatic non-sustained ventricular tachycardia (NSVT) with three PVCs in row, at a frequency of 150 beats per minute (bpm), were detected. After the introduction of beta blockers into therapy, a lower number of PVCs, without NSVT, were recorded in the control 24 h Holter ECG, while transthoracic echocardiography (TTE) showed normal left ventricular (LV) systolic function without cardiomyopathy. So, an exercise test was indicated, and it was interrupted in the third minute at 120 beats per minute (bpm) due to fatigue and pain in the hips, without malignant arrhythmias, angina or dyspneic complaints. During the rest period, a significant inferolateral depression of the ST junction was observed, which recovered in the ninth minute. Immediately after the ECG monitoring stopped, the patient lost consciousness; his pulse was not palpable, but breathing was audible, so cardiac massage was started. After he had regained consciousness, the ECG showed alternating sinus and junctional rhythm with the lowest frequency of 33 bpm, which was accompanied by marked hypotension (80/50 mmHg). The patient was immediately hospitalized; coronary angiography and repeated TTE were completely normal, while continuous ECG monitoring did not confirm malignant rhythm disorders or asystole. It was concluded that it was vasovagal syncope (VVS), most likely caused by the Bezold–Jarisch reflex (BJR).

Effect of ondansetron in maternal hypotension during cesarean delivery: an observational study

Background: Spinal anesthesia is the most common anesthetic technique for cesarean delivery. Thus, hypotension is associated with a reduction in uteroplacental flow which may induce fetal morbidity. Activation of the Bezold Jarisch reflex (mediated by 5HT3 receptors) can worsen hypotension and decrease cardiac output. We studied the effect of ondansetron administration before spinal anesthesia on the trajectory of blood pressure during cesarean delivery. Methods: We conducted a retrospective chart review of all cesarean deliveries that occurred between April 1st 2020 and April 1st 2021 and included 85 pregnant women (43 with ondansetron and 42 in the control group). Data were obtained from the electronic medical record database of the British Hospital of Buenos Aires. Socio- demographic, obstetric, anesthetic and perioperative characteristics of patients were assessed. Results: There were no significant differences in the trajectories of the change from baseline of mean arterial blood pressure between ondansetron and control group (0.14% (95% CI: 0.06 to 0.21) per minute). This also applied to heart rate (-0.10% per minute (95% CI: -0.19 to 0.01). The need of any infusion (phenylephrine or atropine) comparing ondansetron to the reference group was 1.12 (95% CI: 0.68, 1.85). There were eight events of shivering (16.3%) in the ondansetron exposed group and four events of shivering (8.5%) in the reference group. APGAR values showed no clinical difference between groups. Conclusions: In this single-center cohort study, we did not observe an effect of routine administration of ondansetron before spinal anesthesia in cesarean section on improving arterial blood pressure or heart rate throughout the procedure.

Vagal sensory neurons mediate the Bezold–Jarisch reflex and induce syncope

Visceral sensory pathways mediate homeostatic reflexes, the dysfunction of which leads to many neurological disorders1. The Bezold–Jarisch reflex (BJR), first described2,3 in 1867, is a cardioinhibitory reflex that is speculated to be mediated by vagal sensory neurons (VSNs) that also triggers syncope. However, the molecular identity, anatomical organization, physiological characteristics and behavioural influence of cardiac VSNs remain mostly unknown. Here we leveraged single-cell RNA-sequencing data and HYBRiD tissue clearing4 to show that VSNs that express neuropeptide Y receptor Y2 (NPY2R) predominately connect the heart ventricular wall to the area postrema. Optogenetic activation of NPY2R VSNs elicits the classic triad of BJR responses—hypotension, bradycardia and suppressed respiration—and causes an animal to faint. Photostimulation during high-resolution echocardiography and laser Doppler flowmetry with behavioural observation revealed a range of phenotypes reflected in clinical syncope, including reduced cardiac output, cerebral hypoperfusion, pupil dilation and eye-roll. Large-scale Neuropixels brain recordings and machine-learning-based modelling showed that this manipulation causes the suppression of activity across a large distributed neuronal population that is not explained by changes in spontaneous behavioural movements. Additionally, bidirectional manipulation of the periventricular zone had a push–pull effect, with inhibition leading to longer syncope periods and activation inducing arousal. Finally, ablating NPY2R VSNs specifically abolished the BJR. Combined, these results demonstrate a genetically defined cardiac reflex that recapitulates characteristics of human syncope at physiological, behavioural and neural network levels.

C-fos expression in the solitary nucleus medial region and reaction to acute hemorrhage in streptozotocin-stimulated diabetic rats

Examination of circulatory dynamics and autonomic nerve activity in acute hemorrhage in diabetic (DM) rats revealed that despite decreased receptor sensitivity to arterial blood pressure, the DM rats experienced a decline in the heart rate and acceleration of the parasympathetic nerve activity at the sympathoinhibitory phase in response to bleeding (Bezold–Jarisch [B–J] reflex). To elucidate the involvement of the B–J reflex as a reaction to acute hemorrhage in DM rats by assessing c-Fos-positive cell (c-Fos) expression in the nucleus of the solitary tract (SolM), the primary relay nucleus of the baroreflex, Streptozotocin-induced DM and non-DM rats underwent controlled-graded bleeding or continuous phenylephrine infusion under conscious state. Changes in hemodynamics and autonomous nervous system caused by acute hemorrhage and continuous phenylephrine infusion were examined by analyzing blood pressure–heart rate variability. Furthermore, effects of hemorrhage and phenylephrine infusion on the expression of c-Fos in SolM were examined. DM rats showed increased c-Fos expression in response to acute blood loss in the SolM. Non-DM rats showed the same phenomenon in response to continuous phenylephrine infusion in the SolM. Significant interactions between DM and Non-DM rats were observed among hemodynamic and autonomic response to acute hemorrhage and continuous phenylephrine infusion. DM rats were sensitive to acute blood loss, and the circulatory system easily collapsed with accelerating parasympathetic activity in the form of the B–J reflex.

The Vanilloid (Capsaicin) Receptor TRPV1 in Blood Pressure Regulation: A Novel Therapeutic Target in Hypertension?

Today's sedentary lifestyle with excess food and little exercise increases the number of people with hypertension, a major risk factor for stroke. New knowledge of treatments in this field is of utmost importance. In animal experiments, the activation by capsaicin of TRPV1-expressing sensory afferents evokes a drop in blood pressure by triggering the Bezold-Jarisch reflex. In hypertensive rats, capsaicin reduces blood pressure. Conversely, genetic ablation of the TRPV1 receptor results in elevated nocturnal (but not diurnal) blood pressure. These observations imply a therapeutic potential for TRPV1 activation in hypertensive patients. Indeed, in a major epidemiological study involving 9273 volunteers, dietary capsaicin was found to lower the risk for hypertension. New research indicates that the mechanism of action of capsaicin on blood pressure regulation is far more complex than previously thought. In addition to the well-recognized role of capsaicin-sensitive afferents in blood pressure regulation, TRPV1 seems to be expressed both in endothelial cells and vascular smooth muscle. This review aims to evaluate the therapeutic potential of TRPV1-targeting drugs in hypertensive patients.

EFFECT OF INTRAVENOUS ONDANSETRON PREMEDICATION ON SPINAL ANESTHESIA INDUCED HYPOTENSION IN CESAREAN SECTION - A RANDOMIZED CONTROLLED STUDY.

Background:- Spinal anesthesia is the most common anaesthesia technique for cesarean section. In this technique injection of a local anesthetic agent is injected into the subarachnoid space. The most common complication of spinal anesthesia is hypotension which is due to sympathetic blockade and activation of the Bezold Jarisch reex which leads to the utilization of higher doses of vasopressors for the maintenance of blood pressure. The present study was conducted to compare the effect of intravenous ondansetron premedication on spinal anesthesia-induced hypotension with normal saline. An observa methodology:- tional study was conducted in 180 term parturients of ASA - ІІ, scheduled for elective LSCS under spinal anesthesia. The patients were divided into two equal age groups: ondansetron 4mg (group O, n= 90) and saline group (group S, n= 90). Ondansetron 4mg (2ml) was given 10 min before the procedure in group O and group S received 2ml normal saline. Under all aseptic precautions, subarachnoid space was accessed through L3-L4 or L4-L5 intervertebral space using 25G Quincke's spinal needle. After conrmation of the free ow of CSF, a 2ml hyperbaric injection of bupivacaine 0.5% (Heavy) was administered in the subarachnoid space. Mean arterial pressure less than 65mmHg was considered as hypotension and treated with iv mephentermine 6mg bolus. The Occurrence of hypotension in Group O (22.22%) was signicantly l Result- ower than in group S(61.11%)(p<0.001). The MAP was signicantly higher in Group O at 2,4,6,8,10,12,14,16,20 and 25 minutes (p<0.005). 18 (20%) patients required one dose of mephentermine 6mg, and 2(2.22%) patients required two doses in group O. In group S 40 patients ((44.44%) required one dose of mephentermine 10 patients ((11.11%) ) required two doses and 5 patients (5.55%) required 3 doses. In group O 3 patients (3.33%) and in group S, 12 patients (13.33%) had nausea which was statistically signicant with a P value of 0.01. In group S 12 patients (13.33%) and 4 patients (4.44%) in group O had shivering. Which was statistically signicant with a P value of 0.03. Ondansetron is effective in Conclusion – preventing spinal-induced hypotension in elective cesarean section

Comparison of Intravenous Granisetron and Ondansetron on Hemodynamics and Sensory Motor Block After Spinal Anaesthesia With Hyperbaric Bupivacaine in Patients Undergoing Elective Surgery: A Randomized Double-Blind Study.

Bezold Jarisch reflex (BJR) is mediated by peripheral serotonin receptor 5-HT3 type. BJR and sympathetic blockade are important causes of hypotension and bradycardia after spinal anaesthesia. Premedication with serotonin receptor antagonists has a role in the attenuation of hemodynamic disturbances. To compare the effect of intravenous granisetron and ondansetron on the hemodynamic and sensory-motor block after spinal anaesthesia with hyperbaric bupivacaine in patients undergoing elective surgery. Ninety patients posted for elective surgery under spinal anaesthesia were randomly divided into three groups of 30 each. Group A patients received ondansetron 4mg, group B received granisetron 1mg, and group C received normal saline intravenously. Hemodynamic variables such as heart rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, and peripheral oxygen saturation, were recorded at baseline and then 2 minutes intervals for 20 minutes and thereafter every 5 minutes till the end of the surgery. The onset and duration of sensory and motor block were recorded at baseline and then every 2 minutes till the complete block was achieved. No patient was excluded from our study. During the intergroup comparison, heart rate and mean arterial pressure remained stable in group A compared to groups B and C. Time to reach peak sensory block level T4 was faster in group A compared to group B and group C. The rate of sensory block regression to two segments (T4 to T6) and thereafter up to T10, T12, andS1 was faster in group B compared to groups A and C. The attainment of complete motor block, Modified Bromage Score (MBS)=4 was faster in group A compared to group B and group C. The rate of motor block regression to MBS=3 and MBS=0 was faster in group B compared to group A and group C. Premedication with ondansetron 4mg and granisetron 1mg intravenously significantly reduces ephedrine use. Ondansetron provides better hemodynamic stability, earlier onset of the sensory and motor blocks as well as prolonged duration of sensory and motor blocks, and duration of analgesia compared to granisetron.

Bradyarrhythmia in acute massive pulmonary embolism

Pulmonary embolism (PE) can present with a variety of electrocardiographic findings. Bradycardia is a rare finding in acute PE, which typically manifests with sinus tachycardia. Bradycardia in acute PE might arise from the physiologic Bezold–Jarisch reflex, which describes the constellation of bradycardia, peripheral vasodilation, and hypotension. We report the case of a woman in her 60s who was admitted initially for submassive PE and found to have sinus bradycardia. She had progressed to massive PE with acute worsening of atrioventricular conduction block in the setting of atrial flutter. Her bradyarrhythmia resolved and hemodynamics improved after catheter directed thrombolysis. This case revisits the pathophysiology of Bezold–Jarisch reflex, and the importance of recognizing that it signifies an underlying pathologic insult, especially a life-threatening one like PE.

Differential engagement of inhibitory and excitatory cardiopulmonary reflexes by capsaicin and phenylbiguanide in C57BL/6 mice.

The Bezold-Jarisch reflex is a powerful inhibitory reflex initiated by activation of cardiopulmonary vagal nerves during myocardial ischemia, hemorrhage, and orthostatic stress leading to bradycardia, vasodilation, hypotension, and vasovagal syncope. This clinically relevant reflex has been studied by measuring heart rate (HR) and mean arterial pressure (MAP) responses to injections of a variety of chemical compounds. We hypothesized that reflex responses to different compounds vary due to differential activation of vagal afferent subtypes and/or variable coactivation of excitatory afferents. HR and MAP responses to intravenous injections of the transient receptor potential vanilloid-1 (TRPV1) agonist capsaicin and the serotonin 5-HT3 receptor agonist phenylbiguanide (PBG) were measured in anesthetized C57BL/6 mice before and after bilateral cervical vagotomy. Capsaicin and PBG evoked rapid dose-dependent decreases in HR and MAP followed by increases in HR and MAP above baseline. Bezold-Jarisch reflex responses were abolished after vagotomy, whereas the delayed tachycardic and pressor responses to capsaicin and PBG were differentially enhanced. The relative magnitude of bradycardic versus depressor responses (↓HR/↓MAP) in vagus-intact mice was greater with capsaicin. In contrast, after vagotomy, the magnitude of excitatory tachycardic versus pressor responses (↑HR/↑MAP) was greater with PBG. Although capsaicin-induced increases in MAP and HR postvagotomy were strongly attenuated or abolished after administration of the ganglionic blocker hexamethonium, PBG-induced increases in MAP and HR were mildly attenuated and unchanged, respectively. We conclude that responses to capsaicin and PBG differ in mice, with implications for delineating the role of endogenous agonists of TRPV1 and 5-HT3 receptors in evoking cardiopulmonary reflexes in pathophysiological states.

Bezold-Jarisch reflex mediated syncope in pulmonary arterial hypertension: An illustrative case series.

We present a novel description of Bezold-Jarisch Reflex (BJR) during cardiopulmonary exercise testing (CPET) in three young female patients with Group 1 pulmonary arterial hypertension (PAH). These three cases presented within 26 months, representing only 0.8% of 11,387 tests on patients with PAH undergoing CPET during this time frame.

Effect of Intravenous Ondansetron for Prevention of Spinal Anaesthesia Induced Hypotension during Caesarean Section

Introduction: Hypotension is one of the most common complications associated with spinal anaesthesia. Maternal hypotension during caesarean section is more dangerous as it can compromise fetal outcome. Serotonin (5-HT3) has been found to induce Bezold Jarisch Reflex (BJR) causing bradycardia and hypotension in background of decreased blood volume. Ondansetron, a serotonin antagonist may play important role in prevention of spinal induced hypotension. The aim of this study is to determine the effect of intravenous ondansetron to prevent spinal induced hypotension during caesarean section. Methods: A prospective randomised double blind study was done among singleton parturients scheduled for elective caesarean delivery under spinal anaesthesia from July 2nd 2020 to October 31st 2021 in College of Medical Sciences Teaching Hospital. One hundred and thirty patients were randomised by lottery method into two groups (group S and group O) each with 65 patients to receive either 4 mg of intravenous (IV) ondansetron diluted in 10 ml of normal saline or 10 ml of normal saline alone. Various haemodynamic parameters like systolic and diastolic blood pressure (SBP/DBP), mean arterial pressure (MAP), heart rate (HR), oxygen saturation (Spo2) and vasopressor requirement were compared between the two groups using SPSS 20. Student’s t test and chi-square test were used for comparison of parametric and non-parametric data. Results: Incidence of hypotension was 28 (43.07%) in saline group and 11 (16.92%) in ondansetron group. There were statistically significant differences in SBP, DBP and MAP at three, six, nine twelve, fifteen and eighteen minutes. Incidence of shivering was 15 (23.07%) in ondansetron while 28 (43.07%) in saline group which was statistically significant. No other benefit of ondansetron was observed in present study. Conclusions: Prophylactic administration of IV ondansetron could significantly reduce the incidence of spinal induced hypotension during caesarean section.

Sympathetic Nerve Activity and Baroreflex are Strongly Altered in a Context of Severe Hypertension Using the Spontaneously Hypertensive Rat Model Associated with Chronic Reduction of Nitric Oxide.

The aim of our study is to investigate the sympathetic output and baroreflex via renal sympathetic nerve activity (RSNA) recording in a model of severe hypertension which exhibits arterial, cardiac, and renal damages, the spontaneously hypertensive rat (SHR) under lowered NO bioavailability. SHR are treated from 18 to 20 weeks of age with a low dose of L-NAME, a NO synthase inhibitor, in drinking water (SHRLN) and compared to SHR and normotensive Wistar Kyoto (WKY) rats. After the two-week treatment, rats are anesthetized for RSNA, mean blood pressure (MBP), and heart rate (HR) recording. MBP is higher in SHR than in WKY and higher in SHRLN than in SHR. Compared to WKY, SHR displays an alteration in the baroreflex with a displacement of the sympathoinhibition curve to highest pressures; this displacement is greater in SHRLN rats. The bradycardic response is reduced in SHRLN compared to both SHR and WKY. In hypertensive rats, SHR and SHRLN, basal RSNA is modified, the maximal amplitude of burst is reduced, but minimal values are increased, indicating an increased basal RSNA with reduced bursting activity. The temporal correlation between RSNA and HR is preserved in SHR but altered in 10 SHRLN out of 10. The RSNA inhibition triggered by the Bezold–Jarisch reflex activation is not modified in hypertensive rats, SHR or SHRLN, in contrast to that triggered by the baroreflex. Histological analysis of the carotid bifurcation does not reveal any abnormality in SHRLN at the level of the carotid sinus. In conclusion, data indicate that the sympathetic outflow is altered in SHRLN with a strong reduction of the baroreflex sympathoinhibition and suggest that its central pathway is not involved. These additional results on SHRLN also confirm the usefulness of this model of severe hypertension with multiple target organ damages.

The Potential of Granisetron in Preventing Spinal Anesthesia Induced Hypotension on Non-Obstetric Procedure

Hypotension is a common adverse effect seen after spinal anesthesia. In recent literature the use of 5-HT3 receptor antagonists has been proposed to prevent spinal anesthesia induced hypotension (SAIH). We present the use of granisetron in several cases as prevention strategy for SAIH in our center. All 10 eligible subjects received 3 mg granisetron diluted in 10 cc normal saline 5 minutes prior to spinal anesthesia, on patients who undergone non-obstetric procedure. Eight patients showed good response without evidence of hypotension, while the other two patients had hypotension managed well with ephedrine. As many as 9 patients had no bradycardia, while shivering was noted in 3 patients. All patients didn’t suffer from nausea/vomiting, due to its effectiveness of granisetron acts as antiemetic agents. Granisetron, has great affinity specifically for 5-HT3 receptor. It blocked the Bezold Jarisch Reflex (BJR) activation that will lead to hypotension and bradycardia. In a nutshell, granisetron has shown its potential as a prevention strategy for hypotension after spinal anesthesia in the majority of our cases above. Keywords: Hypotension, Spinal anesthesia, granisetron, 5-HT3, BJR.

Reply to "Bezold-Jarisch reflex in the near-term fetus during labor: a matter of time".

Reply to "Bezold-Jarisch reflex in the near-term fetus during labor: a matter of time".

BEZOLD JARISCH REFLEX DURING HALO-GRAVITY TRACTION: CASE REPORT

ABSTRACT Halo-gravity traction is an option that can be used in the treatment of severe spinal deformities. The author reports a complication not yet described in the literature in which rapid correction of the deformity triggered the Bezold Jarisch reflex. Level of evidence IV; Case Series.

Bezold-Jarisch reflex-mediated asystole during dobutamine stress testing: a case report.

BackgroundThe Bezold–Jarisch reflex (BJR) is a cardioinhibitory parasympathetic response to activation of ventricular mechanoreceptors, which can result in bradycardia, atrioventricular block, or asystole. This phenomenon has been triggered by acute myocardial ischaemia, intra-arterial nitroglycerine use, natriuretic peptides, and with exceptional rarity, in middle-aged women only, by dobutamine infusion during stress echocardiography.Case summaryWe present the case of a 61-year-old woman who suffered a 5.1-s sinus pause during her 20 μg/kg/min infusion of dobutamine. Recovery was immediate following termination of dobutamine infusion. Concurrent echocardiography was normal, and subsequent cardiac catheterization and electrophysiologic study were normal.DiscussionThis is the fifth documented case of a severe BJR causing asystole during dobutamine infusion, which adds to the accumulating evidence supporting the benign nature of the condition.

A comparative study between intravenous Ondansetron and Granisetron in attenuation of hypotension during spinal anaesthesia in patients undergoing caesarean section

Hypotension is most common intraoperative complication after spinal anesthesia during cesarean delivery. The Bezold–Jarisch reflex is one of the causes for occurrence of hypotension after spinal anesthesia through serotonin with decreased blood volume. Our aim of this study was to compare the two serotonin receptor antagonists Ondansetron and Granisetron to prevent spinal induced hypotension and bradycardia after spinal anesthesia in parturients undergoing cesarean sections. 90 patients of ASA class-I and II, aged 20-40years, weight 40-80kilograms were included in this study. Patient with history of PIH, convulsion, any major comorbidity were excluded from study. Patients were assigned into 3 groups group A received 4 mg Ondansetron intravenously, group B received 1 mg Granisetron intravenously and group C received 10 ml of intravenous normal saline 5 min before spinal anaesthesia. The difference in mean was analyzed using post hoc Bonferroni test and ANOVA test. The difference in proportions was analyzed by using chi-square test. SBP, DBP and MBP were statistically lower in both Granisetron and Saline group as compared to Ondansetron group at most of the times after drug administration. Heart rate and shivering were comparable in the three groups. Nausea and vomiting was statistically more in saline group as compared to other groups. Use of ephedrine was also significantly more in saline group (37%). 4mg intravenous Ondansetron prior to spinal anaesthesia in LSCS patients reduces the incidence of hypotension, bradycardia and need of vasopressor. Granisetron had no effect on haemodynamic parameters.

Coexistence Of Postural Tachycardia Syndrome And Vasovagal Syncope In The Same Patient.

Postural tachycardia syndrome (PoTS) and vasovagal syncope (VVS) are two prevalent dysautonomic forms of orthostatic intolerance that are linked respectively to a sympathetic hyperactivity and a vagal hyperactivity, but yet, both forms may coexist in the same patient. The mechanism of this association is not well known and the number of published cases remains small to draw management guidelines. We report a case of a healthy 25 years old male who met diagnostic criteria for both PoTS and VVS and who was successfully treated by combining pharmacological and non-pharmacological treatments. We hypothesize through the results of autonomous nervous system (ANS) testing that VVS may be a complication of PoTS through Bezold Jarisch reflex and that the control of PoTS would prevent VVS. Physicians need to be aware of orthostatic intolerance syndromes and resort to ANS tests in patients with a fully normal cardiac workup.

Bezold Jarisch Reflex- New Interest, Old Phenomenon

Bezold Jarisch reflex (BJR) is an eponym for a triad of responses namely: bradycardia, hypotension and vasodilation that develops upon stimulation of intracardiac mechanoreceptors and is mediated by vagal afferent nerve fibers. Though it was first reported in 1867 it remains a topic of discussion due to its implications in various clinical scenarios. The reflex can be stimulated either by mechanical or chemical stimulators. Often considered a physiologic response, if identified by the clinician at earlier phase, can avoid cardiac complication, it also acts as a prognostic indicator in various diseases. This review focuses on the physiology of the BJR and its possible physiologic role in several clinical situations. We used evidence obtained from a computerized literature of medical databases search using PubMed/Medline/NIH (all articles till October 2019). The search was carried out with MeSH phrase “Bezold Jarisch reflex” and articles were limited to English language only. The relevant published reports, abstracts and human studies with clinical cases to determine the clinical implications of BJR were considered for the review. It has been concluded that BJR is a physiologic response that can occur in number of clinical scenarios. Therefore, simultaneous occurrence of bradycardia and hypotension should alert clinicians to the possibility of BJR.

3120 Polyethylene Glycol-Based Bowel Preparation Induced Episodic Sinus Arrest: The Bezold-Jarisch Reflex

INTRODUCTION: The Bezold–Jarisch reflex (BJR) is a cardiac reflex that increases parasympathetic tone and inhibits sympathetic activity, resulting in a clinical triad of bradycardia, hypotension, and peripheral vasodilation. This reflex can be activated by chemical stimuli, such as anesthesia, or by reduced cardiac venous return. Inappropriate reflex bradycardia or asystole can occur. CASE DESCRIPTION/METHODS: A 51-year-old female with no past medical history underwent bowel preparation with a polyethylene glycol-based solution for a routine screening colonoscopy. Before anesthesia was administered, the patient became unresponsive and clonic with a 3-4 second sinus pause. On physical exam, the patient was dehydrated. Electrolyte findings were within normal limits, aside from sodium level of 123 mmol/L. The patient eventually recorded a sinus pause of 30 seconds and a transvenous pacemaker was placed for episodic sinus arrest. The Bezold–Jarisch reflex is a diagnosis of exclusion. The patient had a negative D-dimer, three non-detectable troponin levels and a CT pulmonary angiogram negative for pulmonary embolism. Two electrocardiograms showed normal sinus rhythm, with repeat showing sinus bradycardia; intervals were within normal limits. A transthoracic echocardiogram showed an ejection fraction of 65% with no valvular disease or structural abnormalities. After the patient was fluid resuscitated and electrolytes were optimized, no further episodes were recorded. The patient was fitted with an event monitor and discharged home with close follow up. She remained asymptomatic at outpatient appointment. DISCUSSION: The patient's bowel preparation for her colonoscopy resulted in hypovolemic hyponatremia, upregulating her renin-angiotensin-aldosterone system, whichvagally mediated her episodic sinus arrest via the Bezold–Jarisch Reflex. Given the increasing rate of colonoscopies, this case report highlights the importance of electrolyte-balanced hydration in preventing a potential BJR.