www.lesswrong.com/posts/brxjGPbMy2zCQxFma/why-do-i-believe-preserving-structure-...

This sentence generalizes far beyond what the clinical literature supports.

Cedars-Sinai's patient-education page explains that during typical open-heart surgery, blood continues to circulate, and that hypothermic circulatory arrest was developed to solve a specific problem in aortic surgery. The same page says HCA is now "the standard of care for this surgery"—referring to ascending aortic surgery, not heart surgery broadly.

A review in BJA Education similarly states that most cardiac surgical procedures can be done with cardioplegia and cardiopulmonary bypass, and only some situations require complete cessation of circulation. That directly contradicts the post's claim that HCA became standard for heart operations in general.

The claim is also too broad on the neurosurgery side. A contemporary UCSF surgical series on giant intracranial aneurysms says endovascular advances have "curtailed the use of extreme techniques like hypothermic circulatory arrest"; in that series, HCA was used in only 4 of 141 aneurysms (3%). That is the opposite of a general standard of care for brain operations.

So the accurate version is much narrower: HCA is a specialized technique used for selected complex operations—especially certain aortic procedures—not the standard of care for heart and brain operations as a whole.