TY - JOUR
T1 - The electrocardiogram of vertebrates: Evolutionary changes from ectothermy to endothermy
AU - Boukens, Bastiaan J. D.
AU - Kristensen, Ditte L.
AU - Filogonio, Renato
AU - Carreira, Laura B. T.
AU - Sartori, Marina R.
AU - Abe, Augusto S.
AU - Currie, Shannon
AU - Joyce, William
AU - Conner, Justin
AU - Opthof, Tobias
AU - Crossley, Dane A.
AU - Wang, Tobias
AU - Jensen, Bjarke
PY - 2019/7
Y1 - 2019/7
N2 - The electrocardiogram (ECG) reveals that heart chamber activation and repolarization are much faster in mammals and birds compared to ectothermic vertebrates of similar size. Temperature, however, affects electrophysiology of the heart and most data from ectotherms are determined at body temperatures lower than those of mammals and birds. The present manuscript is a review of the effects of temperature on intervals in the ECG of ectothermic and endothermic vertebrates rather than a hypothesis-testing original research article. However, the conclusions are supported by the inclusion of original data (Iguana iguana, N = 4; Python regius, N = 5; Alligator mississippiensis, N = 4). Most comparisons were of animals of approximately 1 kg. Compared to mammals and birds, the reptiles at 35–37 °C had 4 fold lower heart rates, 2 fold slower atrial and ventricular conduction (longer P- and QRS-wave durations), and 4 fold longer PR intervals (atrioventricular delay) and QT intervals (total ventricular repolarization). We conclude that the faster chamber activation in endotherms cannot be explained by temperature alone. Based on histology, we show that endotherms have a more compact myocardial architecture. In mammals, disorganization of the compact wall by fibrosis associates with conduction slowing and we suggest the compact tissue architecture allows for faster chamber activation. The short cardiac cycle that characterizes mammals and birds, however, is predominantly accommodated by shortening of the atrioventricular delay and the QT interval, which is so long in a 1 kg iguana that it compares to that of an elephant.
AB - The electrocardiogram (ECG) reveals that heart chamber activation and repolarization are much faster in mammals and birds compared to ectothermic vertebrates of similar size. Temperature, however, affects electrophysiology of the heart and most data from ectotherms are determined at body temperatures lower than those of mammals and birds. The present manuscript is a review of the effects of temperature on intervals in the ECG of ectothermic and endothermic vertebrates rather than a hypothesis-testing original research article. However, the conclusions are supported by the inclusion of original data (Iguana iguana, N = 4; Python regius, N = 5; Alligator mississippiensis, N = 4). Most comparisons were of animals of approximately 1 kg. Compared to mammals and birds, the reptiles at 35–37 °C had 4 fold lower heart rates, 2 fold slower atrial and ventricular conduction (longer P- and QRS-wave durations), and 4 fold longer PR intervals (atrioventricular delay) and QT intervals (total ventricular repolarization). We conclude that the faster chamber activation in endotherms cannot be explained by temperature alone. Based on histology, we show that endotherms have a more compact myocardial architecture. In mammals, disorganization of the compact wall by fibrosis associates with conduction slowing and we suggest the compact tissue architecture allows for faster chamber activation. The short cardiac cycle that characterizes mammals and birds, however, is predominantly accommodated by shortening of the atrioventricular delay and the QT interval, which is so long in a 1 kg iguana that it compares to that of an elephant.
UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85053682989&origin=inward
UR - https://www.ncbi.nlm.nih.gov/pubmed/30243548
U2 - https://doi.org/10.1016/j.pbiomolbio.2018.08.005
DO - https://doi.org/10.1016/j.pbiomolbio.2018.08.005
M3 - Article
C2 - 30243548
SN - 0079-6107
VL - 144
SP - 16
EP - 29
JO - Progress in biophysics and molecular biology
JF - Progress in biophysics and molecular biology
ER -