Acute Mesenteric Ischemia: Which Approach Goes First
A single patient, ninety minutes into a bowel that is ischemic but not yet dead. The disagreement isn't about which drug to start — heparin starts regardless — it's about which team reaches him first, and how long that window stays open.
R.T., a 71-year-old man, spent this past year finally making it to his grandson's Saturday morning Little League games, something his electrical-contracting schedule never allowed before he retired last spring. About ninety minutes ago, midway through a plate of eggs, he doubled over with abdominal pain severe enough that his wife called EMS before he had even finished trying to stand up. He has known atrial fibrillation, diagnosed three years ago and nominally managed on apixaban, though he admits — sheepishly, once the pain lets him talk in full sentences — that he has missed several refills since his usual pharmacy closed and he never got around to transferring the prescription. On arrival, his abdomen is soft and only mildly tender to palpation, a mismatch with how much pain he is reporting that the team recognizes immediately as the hallmark of bowel ischemia rather than a surgical abdomen in the ordinary sense.
CT angiography confirms an embolus occluding the proximal SMA, consistent with a fibrillating atrium that has not been reliably anticoagulated. His lactate is rising, but his exam still shows no rebound, no guarding, no peritoneal signs — the window in which bowel is ischemic but not yet dead, and in which how fast a working blood supply gets restored matters more than which instrument restores it. Two teams are now working the same decision from different ends: whether to move him straight to catheter-directed thrombolysis and mechanical thrombectomy in interventional radiology, or straight to the operating room, where an open embolectomy also lets a surgeon look directly at the bowel and resect anything that no longer looks viable. Underneath either choice sits the same pharmacology — full-dose heparin the moment the diagnosis is made, and a vasopressor plan, if his pressure drops, that doesn't undo whatever revascularization buys him.
Two teams, one embolus
Take him to the operating room. An open SMA embolectomy does everything catheter-directed therapy does for the artery, and it does one thing catheter-directed therapy cannot: it lets me put my hands on his bowel and see, in real time, what's viable and what isn't. He has no peritoneal signs now, but bowel viability can change between the CT table and the next hour, and I don't want to be reading a lactate trend from outside the abdomen while that happens.
If this were purely an arterial-patency problem in a patient whose bowel I already trusted, I would have no argument against going endovascular first — the two approaches restore flow about equally well. The disagreement is entirely about who gets to look.
I don't disagree that direct visualization has value once it's actually needed. It isn't needed yet. He has no rebound, no guarding, and a soft abdomen ninety minutes after his pain began — that's a real window, not a fiction, and catheter-directed thrombolysis with aspiration thrombectomy can restore flow through that embolus within the hour without a laparotomy at all. If his exam changes, we haven't lost anything; we convert to open.
The concern about missing a segment of dead bowel matters most in a patient who already has signs suggesting one exists. Right now the only evidence for that is a lactate that could just as easily reflect a fresh occlusion with genuinely salvageable bowel behind it.
Whichever team gets him first, the same two drugs decide whether either approach has time to work. Heparin, full-dose, starts now — not after imaging is reviewed a second time, not after a consent form. One qualifier if interventional radiology goes first: once a catheter-directed alteplase infusion is actually running, the heparin comes down to a subtherapeutic rate rather than staying at full dose, because therapeutic heparin alongside a tissue-plasminogen-activator lytic adds bleeding without adding efficacy. And if his pressure needs support, it's norepinephrine at the lowest dose that holds a mean arterial pressure, never vasopressin — vasopressin is exactly the drug that constricts the mesenteric bed we are trying to reperfuse. I'll take interventional radiology first, on the condition that any peritoneal sign, any exam change, any rising lactate at the one-hour recheck sends him straight to the operating room without another meeting about it.
Agreed within minutes: full-dose heparin infusion started immediately, stepped down to a subtherapeutic rate once catheter-directed alteplase is running; interventional radiology proceeds first with catheter-directed thrombolysis and aspiration thrombectomy, given no peritoneal signs; norepinephrine held in reserve as the sole pressor if needed; piperacillin-tazobactam started empirically; repeat exam and lactate at one hour.
Not agreed, and the reason the plan carries a hard branch point rather than a single expectation:
Lactate falling, exam unchanged or better — the endovascular approach continues, and open exploration is deferred entirely.
Rebound, guarding, or a rising lactate at one hour sends him straight to the operating room for open embolectomy and direct bowel assessment.
Vascular surgery and interventional radiology left holding different expectations about which of them would ultimately be needed. Nobody set a preference between the two teams; the intensivist set a hard threshold instead, and both agreed to honor it without a second meeting.