Intraoperative Bradycardia and Postoperative Hyperkalemia in Patients Undergoing Endoscopic Third Ventriculostomy

Sir,

We have read with interest the article “Intraoperative Bradycardia and Postoperative Hyperkalemia in Patients Undergoing Endoscopic Third Ventriculostomy” by Anandh et al [1] in a previous issue of the Minimally Invasive Neurosurgery.

We noticed that when the authors addressed specific anesthetic considerations they stated that during their initial experience (20 patients) with endoscopic third ventriculostomy (ETV) intraoperative bradycardia was observed. Also they noticed postoperative hyperkalemia in their series associated with ETV. The authors proposed a mechanism involving distortion of the hypothalamus, which accounts for both events. On that assumption they speculated on a central sympathetic and hormonal underlying mechanism.

We would like to draw attention to our published work in which we described in detail a method for measuring 3rd ventricle pressure during ETV. We found a negative correlation between 3rd ventricle pressure and heart rate changes during ETV. In the same study we reported bradycardia in 6 of 14 patients (43 %) [2]. As far as the irrigation fluid is concerned, we used normal saline (0.9 %) without any apparent disturbance of electrolytes, namely hypernatremia or hyperkalemia, which may contradict this paper’s assumption regarding a hormonal mechanism. We would be interested to know if the authors have extended their work to evaluate the hormonal assay during the course of hyperkalemia and correlate it to the serum level of potassium.

We have reported our direct management of intraoperative bradycardia during ETV by withdrawing the scope away from the floor of the 3rd ventricle. We did not encounter any bradycardia upon reversal of the neuromuscular block at the end of the procedure as the authors observed in their study. In another study, we reported bradycardia in 20 of 49 patients (41 %) [3] [4]. We noticed in both studies that bradycardia was the dominant cardiac arrhythmia during ETV. In our study, the anesthetic technique and 3rd ventricle pressure were controlled in all patients whereas we could not see any remarks on 3rd ventricle pressure in the reported study. We agree with the authors that further studies are needed to expand on their observation of postoperative hyperkalemia following ETV.

References

• 1 Anandh B, Madhusudan Reddy K R. et al . Intraoperative bradycardia and postoperative hyperkalemia in patients undergoing endoscopic third ventriculostomy.  Minim Inv Neurosurg. 2002;  45 154-157
• 2 EI-Dawlatly A A, Murshid W, El-Khwsky F. Endoscopic third ventriculostomy: A study of intracranial pressure vs. hemodynamic changes.  Minim Inv Neurosurg. 1999;  42 198-200
• 3 EI-Dawlatly A A. et al . Incidence of bradycardia during endoscopic third ventriculostomy.  Anesth Analg. 2000;  91 1142-1144
• 4 EI-Dawlatly A A. et al . Arrhythmias during neuroendoscopic procedures (Letter to the Editor).  Anesth Analg. 2001;  13 57-58