Dexmedetomidine Depresses Sinoatrial and Atrioventricular Nodal Function Without Any Change in Atrial Fibrillation Inducibility

Effects of Dexmedetomidine on Perioperative Glycemic Control in Adult Diabetic Patients Undergoing Cardiac Surgery

BACKGROUND AND OBJECTIVE

To study the effects of dexmedetomidine (DEX) on perioperative blood glucose levels in adult diabetes mellitus (DM) patients undergoing cardiac surgery.

METHODS AND MATERIAL

A prospective, observational study was conducted on 100 adult diabetic patients aged between 18 and 75 years undergoing cardiac surgery with cardiopulmonary bypass (CPB). The patients were divided into two groups (group D and group C) of 50 each. Group D patients received DEX infusion, whereas the group C patients received 0.9% normal saline infusion.

RESULTS

The blood glucose levels, heart rate, mean arterial pressure, and serum potassium levels at different time points were comparable between the two groups (P > 0.05). The mean dose of insulin required in the combined population as well as in both controlled and uncontrolled DM patients was significantly less in group D than in group C (combined population - 36.03 ± 22.71 vs 47.82 ± 30.19 IU, P = 0.0297; uncontrolled DM - 37.36 ± 23.9 IU vs 48.16 ± 25.15 IU, P = 0.0301; controlled DM - 34.7 ± 21.5 IU vs 47.63 ± 35.25 IU, P = 0.0291). Duration of mechanical ventilation and VIS were comparable between the two groups. The incidence of arrhythmias (20% vs 46%, P = 0.0059) and delirium (6% vs 20%, P = 0.0384) was significantly less in group D than in group C. None of the patients in either group had stroke, myocardial ischemia, and mortality.

CONCLUSION

The results suggested that DEX infusion during the intraoperative period was very effective for perioperative glycemic control and reduction of insulin requirement in DM patients undergoing cardiac surgery.

Impact of dexmedetomidine on electrophysiological properties and arrhythmia inducibility in adult patients referred for reentrant supraventricular tachycardia ablation

BACKGROUND

Drugs used for sedation/analgesia may affect the basic cardiac electrophysiologic properties or even supraventricular tachycardia (SVT) inducibility. Dexmedetomidine (DEX) is a selective alpha-2 adrenergic agonist with sedative and analgesic properties. A comprehensive evaluation on use of DEX for reentrant SVT ablation in adults is lacking. The present study aims to systematically assess the impact of DEX on cardiac electrophysiology and SVT inducibility.

METHODS

Hemodynamic, electrocardiographic, and electrophysiological parameters and SVT inducibility were assessed before and after DEX infusion in patients scheduled for ablation of reentrant SVT.

RESULTS

The population of this prospective observational study included 55 patients (mean age of 58.7 ± 14 years, 29 males [52.7%]). A decrease in systolic and diastolic blood pressure and in heart rate was observed after DEX infusion (p = 0.001 for all). DEX increased corrected sinus node refractory time, atrial effective refractory period, AH interval, AV Wenckebach cycle length, and AV node effective refractory period without affecting the His-Purkinje conduction or ventricular myocardium refractoriness. No AV blocks or sinus arrests occurred during DEX infusion. Globally, there was no difference in SVT inducibility in basal condition or after DEX infusion (46/55 [83.6%] vs. 43/55 [78.1%] patients; p = 0.55), without a difference in isoprenaline use (p = 1.0). In 4 (7.3%) cases, the SVT was inducible only after DEX infusion. In 34.5% of cases, DEX infusion unmasked the presence of an obstructive sleeping respiratory pattern, represented mainly by snoring.

CONCLUSIONS

DEX depresses sinus node function and prolongs atrioventricular refractoriness without significantly affecting the rate of SVT inducibility in patients scheduled for reentrant SVT ablation.

Beneficial Effects of Low-Dose Intravenous Dexmedetomidine Premedication in Patient Undergoing Laparoscopic Cholecystectomy Under General Anesthesia: A Prospective, Double-Blind, Randomized Controlled Trial

Purpose

Dexmedetomidine (Dex) is a potent and highly selective α2-adrenergic receptor agonist. Within an appropriate dose range, Dex can effectively attenuate the surgical stress response, provide intraoperative hemodynamic stability, and improve the patient recovery quality. High-dose Dex can delay patient awakening from anesthesia and increase the incidence of bradycardia. This randomized controlled trial aimed to investigate the effects of low-dose intravenous Dex premedication in patients undergoing laparoscopic cholecystectomy (LC).

Material and Methods

In total, 100 patients undergoing LC were equally randomized into Group C (premedication with saline) and Group D (premedication with 0.5 µg/kg Dex). The patients were premedicated with saline or Dex, depending on the group, before anesthesia induction. Following this, anesthesia induction and endotracheal intubation was performed, and anesthesia was maintained during surgery. Following the completion of the surgery, the patients were transferred the post-anesthesia care unit (PACU) and stayed there until they met the PACU discharge criteria. The hemodynamic parameters, consumption of anesthetics, surgical duration, postoperative awakening time, extubation time, postoperative pain, and complications were recorded.

Results

No significant differences were observed in the heart rate (HR) and mean arterial pressure (MAP) between the two groups before premedication (P>0.05). The MAP and HR immediately after endotracheal intubation and immediately after extubation were significantly lower in Group D than in Group C (P<0.05 for both). The incidence of bradycardia was significantly higher in Group D than in Group C (P<0.05), while atropine was used in neither group. Propofol and remifentanil consumption was significantly lower in Group D than in Group C (P<0.05). The postoperative awakening and extubation times were significantly shorter in Group D than in Group C (P<0.05). The postoperative visual analog scale scores for pain and incidence of nausea, vomiting, and cough were significantly lower in Group D than in Group C (P<0.05 for all).

Conclusion

Our data suggest that premedication with dexmedetomidine (0.5 µg/kg) before general anesthesia induction can effectively attenuate intraoperative stress response and postoperative pain, maintain perioperative hemodynamic stability, and decrease the incidence of adverse events, which might be an effective and safe anesthetic protocol during LC worthy of further clinical application.

Effects of Dexmedetomidine on Basic Cardiac Electrophysiology in Adults; a Descriptive Review and a Prospective Case Study

Dexmedetomidine (DEX) is a commonly used sedative agent with no or minimal effects on breathing. DEX may also be beneficial in myocardial protection. Since the mechanisms of cardiac effects are not well known, we carried out a descriptive review and examined the effects of DEX on myocardial electrical conduction in a prospective and controlled manner. For the review, clinical studies exploring DEX in myocardial protection published between 2020-2022 were explored. A case study included 11 consecutive patients at a median (range) age of 48 (38-59), scheduled for elective radiofrequency ablation of paroxysmal atrial fibrillation. A bolus dose of DEX 1 µg/kg given in 15 min was followed by a continuous infusion of 0.2-0.7 µg/kg/h. Direct intracardiac electrophysiologic measurements, hemodynamics and oxygenation were measured before and after the DEX bolus. Experimental studies show that DEX protects the heart both via stabilizing cardiac electrophysiology and reducing apoptosis and autophagy after cell injury. The clinical evidence shows that DEX provides cardiac protection during different surgeries. In a clinical study, DEX increased the corrected sinus node recovery time, prolongated the atrioventricular (AV) nodal refractory period and cycle length producing AV nodal Wenckebach retrograde conduction block. DEX has a putative role in organ protection against hypoxic, oxidative and reperfusion injury. DEX slows down the firing of the sinus node and prolongs AV refractoriness.

Dexmedetomidine Sedation for Paroxysmal Supraventricular Tachycardia Ablation Is Not Associated With Alteration of Arrhythmia Inducibility

BACKGROUND

Dexmedetomidine (Dex) is an attractive agent for procedural sedation due to its unique pharmacodynamic profile, specifically affording predictable sedation without concurrent respiratory depression. However, Dex has previously been reported to prevent or terminate arrhythmias. The purpose of this study was to investigate paroxysmal supraventricular tachycardia (PSVT) inducibility and homeostatic stability during electrophysiology studies (EPSs) and ablation when a standardized Dex protocol was used as the primary sedation agent.

METHODS

We performed a retrospective review of 163 consecutive procedures for PSVT ablation that received Dex as the primary sedative with adjunct fentanyl and midazolam boluses (DEX-FENT-MIDAZ). This cohort was compared to 163 consecutive control procedures wherein strictly fentanyl and midazolam were used for sedation. The primary outcome reviewed was PSVT inducibility assessed before ablation. Reviewed secondary outcomes included level of sedation and intraprocedure hemodynamics and oxygenation.

RESULTS

The arrhythmia profiles of the DEX-FENT-MIDAZ and control cohorts were very similar. The overall incidence of a "negative" EPSs in which arrhythmia was not induced was 24% in the DEX-FENT-MIDAZ group and 26% in the control group (P = .7). Unintended deep sedation was significantly less with DEX-FENT-MIDAZ (4.3% vs 27%; P ≤ .0001). However, DEX-FENT-MIDAZ use was associated with a higher incidence of intraprocedure hypotension.

CONCLUSIONS

Dex sedation during EPSs is not associated with a reduction in PSVT inducibility. The therapeutic utility of Dex during EPS arises from the predictable sedation Dex affords but is associated with an increased incidence of intraprocedure hypotension.