Emergent Non-Cardiac Surgery in a Patient with an Evolving Acute Myocardial Infarction
Chris Swinney, MD and Timothy E. Morey, MD
Department of Anesthesiology, University of Florida College of Medicine
Case Report: A 72-year-old man was brought to the operating room
emergently for endovascular stent graft repair of a ruptured
abdominal aortic aneurysm (AAA). The day before, he had
experienced sudden, excruciating back and flank pain, but was
hesitant to seek medical attention, and had been found
unresponsive the following day by family members. After initial
volume resuscitation and evaluation at a nearby community
hospital, he was transferred to our institution for emergent
repair of his ruptured 10 cm AAA and treatment of his myocardial
ischemia. His medical history was largely unknown due to his
longstanding reticence toward medical care.
Upon arrival, he was hemodynamically stable with blood pressure
of 113/69 mmHg, heart rate of beats/min, and mentating well.
Inferior ST depression and lateral ST elevation were present.
Sublingual nitroglycerin spray was given, as well as 325 mg of
aspirin. After arterial line insertion under local anesthesia,
rapid sequence induction proceeded with etomidate, fentanyl, and
succinylcholine; anesthesia was maintained with low-dose
isoflurane and fentanyl. Pancuronium was used for muscle
relaxation. Initial intraoperative hematocrit was 13%, and was
aggressively corrected with 6 units packed red blood cells to
31%. Intravenous nitroglycerin infusion was initiated and
titrated up to 4 µg/kg/min; ß-blockade was achieved with
metoprolol IV. Ischemic EKG changes persisted despite these
measures.
Transesophageal echocardiography demonstrated profound, global
hypokinesis. Milrinone infusion was started at 0.5 µg/kg/min
after a loading bolus of 50 µg/kg over 10 minutes. Left
ventricular function appreciably improved, and continued to do
so with titration of the infusion to 0.75 µg/kg/min. Ischemic
EKG features remained unchanged.
Surgery concluded without further event, and the patient was
emergently taken to the cardiac angiography laboratory for
coronary intervention. Severe three-vessel disease was found,
including acute thrombotic occlusions of the right and
circumflex vessels, which were successfully angioplastied and
stented. Transthoracic echocardiography on postoperative day 2
demonstrated multiple hypokinetic and akinetic segments, with
overall left ventricular ejection fraction 30-40%.
His post-operative course was complicated by respiratory
failure, which ultimately resolved, and renal failure, which did
not; the patient was discharged on postoperative day 59 with
arrangements for ongoing hemodialysis.
Discussion: The use of a positive inotrope, such as milrinone,
in the setting of acute myocardial ischemia raises concern of
increasing myocardial oxygen demand and worsening the severity
of ischemia.
