Hi ad welcome to HCM.
I am sorry that it happened, It is not common after such procedure but complications are always possible.
In these situation there is a rule: "all or nothing". First 5 days after incident are most important. Acute bleeding always causes more or less significant kidney
,heart ,lungs and liver damage
.It is called multiple organ failure and honestly is extremely serious condition which needs to be agresively treated which obviously is considering what you have said. Prognosis is always unpredictable.Now it is most important to save his heart and circulation function, after this everything will be better. I hope everything will be fine.
WIsh you good health.