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Graft Flow Decline After Protamine Administration in Coronary Artery Bypass Grafting: Incidence, Outcomes, and Treatments
Hiroyuki Tsukui, Mitsugu Ogawa
Independence Health System, Greensburg, Pennsylvania, United States
Background: Graft flow (GF) decline after protamine administration in coronary artery bypass grafting (CABG) is a rare and life-threatening complication but remains unclear. This study reports the incidence, outcomes, and treatment options for GF decline after protamine administration in CABG.
Methods: This was an observational study of CABG from September 2019 to June 2024 at a single center. A total of 942 patients underwent isolated CABG with off-pump, on-pump beating, and on-pump arrest techniques in 683 (72.5%), 89 (9.4%), and 170 (18.0%), respectively. Initial heparin dosage was 350 units/kg to reach ACT >400 seconds for on-pump, and 260 units/kg to reach ACT>350 seconds for off-pump. Additional heparin was given to reach the target ACT level during the procedure. Excellent GF was confirmed with transit time flow measurement before protamine administration. Protamine is administered at 0.75mg for 1,000 units of heparin for over 10 minutes. The incidence, outcomes, and treatments of GF decline were analyzed.
Results: GF decline was observed in 15 patients (1.6%). 53 distal anastomoses (mean: 3.5/patient) with 27 arterial and 15 venous grafts were performed with off-pump in 13, on-pump beating in 1, and conversion from off-pump to on-pump in 1. After protamine administration, GF decreased to zero in 10 patients in all grafts, whereas in 5 patients in some of the grafts. The timing of GF decline was during chest closure in 12, after chest closure in 2, and after arrival in ICU in 1. 13 patients (86.7%) required cardiopulmonary bypass (CPB) support because of unstable hemodynamics. 3 patients recovered with medication only. 10 patients had a revision in 23 distal anastomoses. 8 patients required thrombectomy in 19 distal anastomoses, whereas 7 had no evidence of thrombus. 12 patients had complete GF recovery in 35 grafts. 6 patients had additional CABG for non-recovered GF areas. Intra-aortic balloon pump (IABP) and temporary left ventricular assist device (LVAD) were inserted in 7 and 2 patients, respectively. 6 of 8 patients screened for heparin-induced thrombocytopenia (HIT) were positive. 14 patients were discharged, but one with HIT positive died due to repeated thrombosis 4 days after surgery. 6 patients had decreased LVEF at discharge.
Conclusions: GF decline after protamine administration occurred in 1.6% of patients who underwent CABG. Most of GF decline was observed in off-pump technique. Half of GF declines were due to thrombosis, and the other half were of spastic reaction origin. Most of the patients required CPB support because of unstable hemodynamics. Both revisions of distal anastomosis for acute thrombosis and medical management for spastic reaction are reasonable approaches. Circulatory support with IABP and temporary LVAD were an effective strategy to stabilize hemodynamics. Most patients could recover from GF decline with appropriate management, but some patients had decreased LVEF at discharge.
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