Response to Letter Regarding Article, “Electrical Heart Activity Recorded During Prolonged Avalanche Burial”
We thank Pettit et al for their comments on our article on electrical heart activity recorded during prolonged avalanche burial.1 They raised concerns about the accuracy of the recorded data, attributing phases of constant frequency to artifact. To address potential technical failure of the device, several tests were performed directly after the accident and additional details were verified. First, the victim was found fully dressed in several layers with no repositioning of the clothing and, once undressed, the belt was found correctly situated and secure on the chest. Thus, it seems implausible that any shifting of the device relative to the victim's skin had occurred. Second, the sports watch and chest belt were tested jointly with the manufacturer of the device and were found to be functioning correctly; in particular, potential external disturbances to the recording capacity of the device (eg, avalanche transceiver) were excluded. Third, the drop in heart rate to 0 corresponded to the time of extrication of the victim indicated in the rescue protocol. Thus, the variability occurring in the final minutes of the fourth phase may represent a movement-invoked disturbance during the rescue operation. Last, it should be specified that the data-recording interval of this device was 20 s.
Despite the fact that it would be presumptuous to assign the constant frequencies of the second, third, and fourth phases to supraventricular or ventricular episodes of tachycardia or bradycardia, it is known from clinical cases2 and experimental investigations that hypothermia causes numerous variable arrhythmias. Danzl3 states that “below 32.0°C (89.6°F) all types of atrial and ventricular arrhythmias are encountered.” We believe it can be concluded that these data represent electrical cardiac activity recorded throughout the duration of burial until the time of extrication and that technical failure has been excluded by all possible means after the accident.
Giacomo Strapazzon, MD
Emily Procter, MSc
Hermann Brugger, MD
Institute of Mountain Emergency Medicine
Werner Beikircher, MD
Department of Anaesthesiology
General Hospital of Brunico
- © 2012 American Heart Association, Inc.