‘Interesting study’
Two experts who were not involved with this research weighed in on the findings for this news organization.
“This very interesting study reinforces the difficulties in xenotransplantation, and the need for more research to be able to safely monitor recipients, as baseline values are unknown,” said Edward Vigmond, PhD.
Dr. Vigmond, from the Electrophysiology and Heart Modeling Institute at the University of Bordeaux in France, published a related study about a model of translation of pig to human electrophysiology.
The ECG is sensitive to the electrical activation pattern of the heart, along with the cellular and tissue electrical properties, he noted.
“Although pigs and humans may be similar in size, there are many differences between them,” Dr. Vigmond observed, including “the extent of the rapid conduction system of the heart, the number of nuclei in the muscle cells, the proteins in the cell membrane which control electrical activity, the orientation of the heart and thorax, and the handling of calcium inside the cell.”
“On top of this,” he continued, “donor hearts are denervated, so they no longer respond to nervous modulation, and circulating compounds in the blood which affect heart function vary between species.
“With all these differences, it is not surprising that the ECG of a pig heart transplanted into a human resembles neither that of a human nor that of a pig,” Dr. Vigmond said.
“It is interesting to note that the humanized-gene-edited porcine heart exhibited abnormal electrical conduction parameters from the outset,” said Mandeep R. Mehra, MD.
“Whether these changes were due to the gene modifications (i.e., already inherent in the pig ECG prior to transplant) or a result of the transplant operation challenges (such as the ischemia reperfusion injury and early immunological interactions) is uncertain and should be clarified,” said Dr. Mehra, of Harvard Medical School and Brigham and Women’s Medicine in Boston.
“Knowledge of these changes is important to determine whether a simple ECG parameter may be useful to identify changes that could indicate developing pathology,” Dr. Mehra added.
“In the older days of human transplantation, we often used ECG parameters such as a change in voltage amplitude to identify signals for rejection,” he continued. “Whether such changes occurred in this case could be another interesting aspect to explore as changes occurred in cardiac performance in response to the physiological and pathological challenges that were encountered in this sentinel case.”
The study authors reported having no outside sources of funding.
A version of this article first appeared on Medscape.com.