Perioperative bradycardia and asystole: relationship to vasovagal syncope and the Bezold–Jarisch reflex

Abstract

Reflex cardiovascular depression with vasodilation and bradycardia has been variously termed vasovagal syncope, the Bezold-Jarisch reflex and neurocardiogenic syncope. The circulatory response changes from the normal maintenance of arterial pressure, to parasympathetic activation and sympathetic inhibition, causing hypotension. This change is triggered by reduced cardiac venous return as well as through affective mechanisms such as pain or fear. It is probably mediated in part via afferent nerves from the heart, but also by various non-cardiac baroreceptors which may become paradoxically active. This response may occur during regional anaesthesia, haemorrhage or supine inferior vena cava compression in pregnancy; these factors are additive when combined. In these circumstances hypotension may be more severe than that caused by bradycardia alone, because of unappreciated vasodilation. Treatment includes the restoration of venous return and correction of absolute blood volume deficits. Ephedrine is the most logical choice of single drug to correct the changes because of its combined action on the heart and peripheral blood vessels. Epinephrine must be used early in established cardiac arrest, especially after high regional anaesthesia.

Witnessed asystole during spinal anesthesia treated with atropine and ondansetron: a case report

“…In recent reviews of the etiology of arrests under spinal anesthesia, the Bezold-Jarisch reflex (BJR) is one of the mechanisms implicated. [1][2][3][4][5][6][7][8] In some animals the BJR can be abolished with 5-HT 3 antagonists. [9][10][11] Current recommendations to treat asystole during spinal block include immediate restoration of volume by gravity or fluid bolus, early use of atropine, ephedrine, epinephrine, vasopressin, and thump pacing.…”

“…The early use of epinephrine and volume restoration (and the relative inefficacy of atropine) have been emphasized previously. [4][5][6][7][8]12 The following is a case of witnessed asystole during spinal anesthesia treated with a combination of iv atropine and ondansetron.…”

Coronary artery spasm and non-Q-wave myocardial infarction following intravenous ephedrine in two healthy women under spinal anaesthesia

“…3 4 Surgery is indicated for large free lower oesophageal perforations 4 or complications, for example mediastinitis. 5 In the case reported here, the exact level of perforation was not clear but was in the upper oesophagus, and she initially progressed satisfactorily with conservative treatment. Signs of systemic sepsis developed, with respiratory failure and cardiovascular instability.…”

“…The use of the sitting position for easier siting of combined spinal-epidural analgesia may have further increased the risk of a vasovagal episode. 5 In Case 2, a clearly anxious patient with a history of vasovagal syncope and some vasovagal reaction even before the start of the procedure, exhibited a rather high level of spinal block that was well tolerated until she was turned to a lateral position. In contrast to the first patient, she was administered a larger volume of i.v.…”

“…Vasovagal fainting is associated with an increased vagal, and a decreased sympathetic, activity explaining bradycardia and hypotension, respectively. 5 Kinsella and Tuckey 5 therefore suggest ephedrine as the logical first-line drug treatment of bradycardia during spinal anaesthesia, whereas others recommend atropine first and then ephedrine. 3 In order to prevent fatal cardiac arrest under spinal anaesthesia early aggressive treatment of bradycardia and hypotension with fluids, atropine, ephedrine and eventually epinephrine is recommended.…”