Complete atrioventricular nodal block after propofol administration in an elderly patient undergoing total knee replacement arthroplasty -A case report-

Effect of Propofol in the Cardiovascular System and its Related Mechanism Research Progress

Propofol is the most widely used short-acting intravenous anesthetic in clinical practice. Existing studies have shown that propofol has many effects on the cardiovascular system in addition to its anesthetic effect. Propofol can antagonize a variety of tachyarrhythmias and reduce the risk of recurrence, regulate autonomic balance of the heart, modulate circulatory dynamics, thereby increasing blood perfusion to vital organs such as the kidney, intestine, and brain, and exert myocardial protection and cerebral protection during ischemia-reperfusion injury. In this paper, we review the potential mechanisms of these effects and provide and ideas for future research and novel drug development of propofol and its derivatives in cardiac electrophysiology and circulatory dynamics.

Electrophysiological differences of randomized deep sedation with dexmedetomidine versus propofol

BACKGROUND

Dexmedetomidine and propofol are common sedatives in intensive care units and for interventional procedures. Both may compromise sinus node function and atrioventricular conduction. The objective of this prospective, randomized study is to compare the effect of dexmedetomidine with propofol on sinus node function and atrioventricular conduction.

METHODS

In a tertiary care center in Switzerland we included from September 2019 to October 2020 160 patients (65 ± 11 years old; 32% female) undergoing first ablation for atrial fibrillation by cryoballoon ablation or by radiofrequency ablation. Patients were randomly assigned to deep sedation with dexmedetomidine (DEX group) versus propofol (PRO group). A standard electrophysiological study was performed after pulmonary vein isolation with the patients still deeply sedated and hemodynamically stable.

RESULTS

Eighty patients each were randomized to the DEX and PRO group. DEX group patients had higher baseline sinus cycle length (1022 vs. 1138 ms; p = 0.003) and longer sinus node recovery time (SNRT400; 1597 vs. 1412 ms; p = 0.042). However, both corrected SNRT and normalized SNRT did not differ. DEX group patients had longer PR interval (207 vs. 186 ms; p = 0.002) and AH interval (111 vs. 95 ms, p = 0.008), longer Wenckebach cycle length of the atrioventricular node (512 vs. 456 ms; p = 0.005), and longer atrioventricular node effective refractory period (390 vs. 344 ms; p = 0.009). QRS width and HV interval were not different. An arrhythmia, mainly atrial fibrillation, was induced in 33 patients during the electrophysiological study, without differences among groups (20% vs. 15%, p = 0.533).

CONCLUSIONS

Dexmedetomidine has a more pronounced slowing effect on sinus rate and suprahissian AV conduction than propofol, but not on infrahissian AV conduction and ventricular repolarization. These differences need to be taken into account when using these sedatives.

TRIAL REGISTRATION

ClinicalTrials.gov number NCT03844841, 19/02/2019.

Remimazolam as the Primary Agent for Sedation During Cardiac Catheterization in Three Patients With Comorbid Cardiac Conduction Abnormalities

General anesthesia or procedural sedation may be required to ensure immobility, facilitate completion of the procedure, and ensure patient comfort during diagnostic or therapeutic procedures in the cardiac catheterization suite. Although propofol and dexmedetomidine are two of the more commonly chosen agents, concerns regarding their impact on inotropic, chronotropic or dromotropic function may limit their applicability based on underlying patient comorbid conditions. We present three patients with comorbid conditions involving pacemaker (natural or implanted) function or cardiac conduction which impacted the choice of agent for procedural sedation during procedures in the cardiac catheterization suite. Remimazolam, a novel ester-metabolized benzodiazepine, was used as the primary agent for sedation in an effort to limit detrimental effects on chronotropic and dromotropic function which may be seen with propofol or dexmedetomidine. Remimazolam's potential utility in procedural sedation is discussed, previous reports of its use are reviewed, and dosing algorithms are presented.

Propofol suppresses the His-ventricular conduction in paediatric patients

What is known and objective

Propofol is the most commonly used intravenous anaesthetic worldwide and is considered to be safe for all ages. However, there have been some reports that propofol induces severe atrioventricular (AV) blocks in humans and some studies demonstrated that propofol suppressed the cardiac conduction system in animals. A precise mechanism by which the block is induced has not been elucidated yet in humans. The objective of this study was to investigate the effects of propofol on the cardiac conduction system and the cardiac autonomic nervous balance in children.

Methods

We enrolled 23 paediatric patients (age: 6‐15 years; males: 16, females: 7) who were scheduled to undergo radiofrequency catheter ablation (RFCA) under general anaesthesia. Anaesthesia was induced with 2 mg/kg propofol and 0.5 µg/kg/min remifentanil, and tracheal intubation was performed with the aid of 1 mg/kg rocuronium. Anaesthesia was maintained with 5‐7 mg/kg/h propofol and 0.2 µg/kg/min remifentanil during the RFCA. After the completion of the RFCA, anaesthesia was further maintained with 5 mg/kg/h propofol and 0.2 µg/kg/min remifentanil for at least 10 min (LC: low propofol concentration state), followed by the injection of 2 mg/kg propofol and the infusion of 10 mg/kg/h propofol for 10 min (HC: high propofol concentration state). The sinus node recovery time (SNRT), sinoatrial conduction time (SACT), atrial‐His (AH) interval and the His‐ventricular (HV) interval were measured at the end of both the LC and HC. Cardiac autonomic regulation was simultaneously assessed based on heart rate variability.

Results and discussion

Propofol significantly suppressed intrinsic cardiac HV conduction, but did not affect the SNRT, SACT or the AH interval. As HV blocks, which occur below the His bundle, are often life‐threatening, the HV conduction delay may be a cause of severe AV blocks induced by propofol. Propofol directly suppressed parasympathetic nerve activity, and sympathetic nerve activity was also suppressed.

What is new and conclusion

These results indicate that propofol suppresses the HV conduction and might help to elucidate the mechanism by which propofol causes lethal AV blocks.

Elective Inguinal Hernia Surgery in the Setting of Unfollowed Congenital Complete Heart Block With No Postponement

Most preoperatively discovered complete heart block cases without cardiac clearance in a non-emergent situation are managed with deferral of elective surgery until a cardiology workup can be completed. The medical consequences of surgical delays can manifest in increased costs to the healthcare system via the treatment of more advanced disease, often requiring more intense and more costly treatment in addition to the emotional burden of delay on a patient that has been waiting months for a particular surgery. Delays in surgery have real impacts on patient health outcomes, hospital finances, and patient satisfaction. We present a rare case in which a proactive anesthesiologist was able to take measures to stratify patient safety risk and safely prevent the delay of the surgery in an asymptomatic and unfollowed congenital third-degree heart block patient. The anesthesiologist demonstrates the use of established guidelines for non-elective noncardiac surgery to safely and effectively prevent the delay of an elective inguinal hernia repair in the setting of a situation that normally warrants its delay. Using these pre- and intraoperative measures, the anesthesiologist was able to prevent the delay of elective surgery, and this should set a precedent of the necessary steps involved to safely manage a patient with an unfollowed third-degree congenital heart block.

Serious Cardiovascular Adverse Events Reported with Intravenous Sedatives: A Retrospective Analysis of the MedWatch Adverse Event Reporting System

BACKGROUND

Serious cardiovascular adverse events (SCAEs) associated with intravenous sedatives remain poorly characterized.

OBJECTIVE

The objective of this study was to compare SCAE incidence, types, and mortality between intravenous benzodiazepines (i.e., diazepam, lorazepam, and midazolam), dexmedetomidine, and propofol in the USA over 8 years regardless of the clinical setting where it was administered.

METHODS

The Food and Drug Administration's MedWatch Adverse Event Reporting System was searched between 2004 and 2011 using the Evidex^® platform from Advera Health Analytics, Inc. to identify all reports that included one or more of ten different SCAEs (package insert incidence ≥ 1%) and where an intravenous benzodiazepine, dexmedetomidine, or propofol was the primary suspected drug.

RESULTS

Among the 2326 Food and Drug Administration's MedWatch Adverse Event Reporting System cases reported, 394 (16.9%) were related to a SCAE. The presence of a SCAE (vs. a non-SCAE) is associated with higher mortality (34 vs. 8%, p < 0.001). The percentage of cases with one or more SCAE, the case mortality rate (%), and the incidence of each SCAE (per 10⁶ days of sedative exposure), respectively, were benzodiazepines (14, 26, 13) [diazepam (13, 23, 31); lorazepam (15, 43, 14); midazolam (14, 20, 11)]; dexmedetomidine (40, 15, 13); and propofol (17, 39, 7). Propofol (vs. either a benzodiazepine or dexmedetomidine) was associated with more total SCAEs (268 vs. 126, p < 0.001) but a lower incidence (per 10⁶ days of sedative exposure) of SCAE (7 vs. 13, p = 0.0001) and cardiac arrest [6.3 (benzodiazepine) vs. 6.7 (dexmedetomidine) vs. 1.4 (propofol), p < 0.0001].

CONCLUSIONS

Serious cardiac adverse events account for nearly one-fifth of intravenous sedative Food and Drug Administration's MedWatch Adverse Event Reporting System reports. These SCAEs appear to be associated with greater mortality than non-cardiac serious adverse events. Serious cardiac events may be more prevalent with either benzodiazepines or dexmedetomidine than propofol.

Persistent Complete Atrioventricular Block after Induction of General Anesthesia in a Healthy Patient

<p>A 38-year-old female patient had bradycardia in the preoperative electrocardiogram (ECG), and she showed severe bradycardia, with the heart rate (HR) under 40 beats per minute (bpm) even after arrival in the operating room. Immediately after endotracheal intubation, ventricular tachycardia with HR over 200 bpm occurred, but it disappeared voluntarily. The surgery was postponed for additional cardiac evaluation because of the persistent severe bradycardia. On postanesthesia day 2, complete atrioventricular (AV) block appeared. We expected spontaneous recovery over 2 weeks, but the complete AV block persisted. A permanent pacemaker was eventually inserted, and the patient was discharged without other complications on day 4 after insertion of the pacemaker. We report this case because complete AV block has commonly occurred in patients with risk factors such as first AV block, secondary AV block, or bundle branch block, but complete AV block has occurred despite the absence of arrhythmia in this patient.</p>

Intravenous Anesthetic Propofol Inhibits Multiple Human Cardiac Potassium Channels

Background:

Propofol is widely used clinically for the induction and maintenance of anesthesia. Clinical case reports have shown that propofol has an antiatrial tachycardia/fibrillation effect; however, the related ionic mechanisms are not fully understood. The current study investigates the effects of propofol on human cardiac potassium channels.

Methods:

The whole cell patch voltage clamp technique was used to record transient outward potassium current (Ito) and ultrarapidly activating delayed rectifier potassium current (IKur) in human atrial myocytes and hKv1.5, human ether-à-go-go-related gene (hERG), and hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells. Current clamp mode was used to record action potentials in human atrial myocytes.

Results:

In human atrial myocytes, propofol inhibited Ito in a concentration-dependent manner (IC50 = 33.5 ± 2.0 μM for peak current, n = 6) by blocking open channels without affecting the voltage-dependent kinetics or the recovery time constant; propofol decreased IKur (IC50 = 35.3 ± 1.9 μM, n = 6) in human atrial myocytes and inhibited hKv1.5 current expressed in HEK 293 cells by preferentially binding to the open channels. Action potential duration at 90% repolarization was slightly prolonged by 30 μM propofol in human atrial myocytes. In addition, propofol also suppressed hERG and hKCNQ1/hKCNE1 channels expressed in HEK 293 cells.

Conclusion:

Propofol inhibits multiple human cardiac potassium channels, including human atrial Ito and IKur, as well as hKv1.5, hERG, and hKCNQ1/hKCNE1 channels stably expressed in HEK 293 cells, and slightly prolongs human atrial action potential duration, which may contribute to the antiatrial tachycardia/fibrillation effects observed in patients who receive propofol.