Cardiac arrest following protamine administration

Kounis syndrome caused by protamine shock after coronary intervention: A case report

We report a case of Kounis syndrome that led to shock after protamine administration during percutaneous coronary intervention (PCI). A man in his 50s was admitted to the nearest hospital following the onset of acute myocardial infarction. Coronary angiography showed a single-vessel lesion in the left anterior descending artery (LAD). He was admitted for PCI. After heparin administration, the procedure was completed by implantation of a coronary stent with the usual procedure. For hemostasis, following protamine administration, the patient went into shock. Subsequently, electrocardiography showed bradycardia with ST-segment elevation at leads II, III, aVF, and V3-6. Cardiopulmonary resuscitation was started immediately. As pulseless electrical activity continued, extracorporeal membrane oxygenation (ECMO) was introduced. Coronary angiography demonstrated coronary spasm in the LAD. He was withdrawn from the ECMO on day 7. His intradermal tests were positive for protamine in the convalescent phase. The patient was diagnosed with protamine shock and type I Kounis syndrome. Protamine shock is not uncommon, but Kounis syndrome may be hidden in it. Thus, similar cases should not be treated as a simple protamine shock. <Learning objective: This case report aimed to determine 1) the mechanism of protamine shock and its risk factors, and 2) the pathogenesis and type of Kounis syndrome in a patient who developed protamine shock, and 3) the significance of ST-elevation during anaphylactic shock.>.

Intraoperative Heparin Use during Upper Extremity Arteriovenous Access Creation Does Not Affect Outcomes

BACKGROUND

There are conflicting data about the effect of heparin use on perioperative outcomes during upper extremity arteriovenous (AV) access creation. Our goal was to assess the effect of the use and degree of intraoperative heparin on perioperative outcomes after AV access creation.

METHODS

All upper extremity AV access cases performed at a tertiary academic medical center between 2014 and 2017 were reviewed. Patient and procedural details including intraoperative heparin use and dosing as well as protamine use were analyzed. Full heparin dose was defined as 80-100 U/kg and partial heparin dose as less than 80 U/kg. Perioperative arterial thrombosis or distal embolism, hematoma, and early loss of primary patency within 30 days were evaluated. Multivariate analysis was performed to assess the effect of heparin use.

RESULTS

There were 550 AV access cases identified: brachiocephalic (37.5%), brachiobasilic (29.3%), and radiocephalic fistulas (12.9%), and AV grafts (16.9%). Average patient age was 62.6 years and 58.9% were male. Full heparinization was used in 21.3%, partial heparinization in 58.7%, and no heparin was used in 20% of cases. Protamine was used in 94.9% of full heparin cases and 51.4% of partial heparin cases. No perioperative arterial thrombosis or distal embolism was observed. Perioperative wound hematoma rate was 3.4%, 3.1%, and 0.9% in full heparin, partial heparin, and no heparin cohorts, respectively (P = 0.42). Early loss of primary patency was 11.1%, 7.7%, and 6.4% for full heparin, partial heparin, and no heparin cases, respectively (P = 0.39). There were no differences in return to the operating room or perioperative survival. On multivariable analysis, full heparin use (odds ratio [OR] 3.82, 95% confidence interval [CI] 0.41-35.9, P = 0.24) and partial heparin (OR 4.03, 95% CI 0.5-32.6, P = 0.19) use were not significantly different from no heparin cases with respect to 30-day perioperative hematoma rate. Full heparin (OR 1.76, 95% CI 0.65-4.78, P = 0.26) and partial heparin (OR 1.13, 95% CI 0.46-2.75, P = 0.79) were not significantly different from no heparin cases with respect to early loss of primary patency.

CONCLUSIONS

Intraoperative heparin use, at full or partial doses, did not affect perioperative outcomes after AV access creation. Overall complication event rate was low for all groups. AV access can be safely performed without intraoperative heparin use.

Nitric oxide inhibition attenuates systemic hypotension produced by protamine

BACKGROUND

Protamine reversal of heparin anticoagulation often causes systemic hypotension, and in vitro studies suggest that this may be mediated by release of nitric oxide from the endothelium. The present investigations were designed to evaluate the direct myocardial effects of protamine and to determine in vivo whether nitric oxide inhibition can prevent hypotension during protamine infusion.

METHODS/RESULTS

Protamine sulfate (50 microg/ml) was added to perfusate of eight isolated rabbit heart preparations; in six other preparations, a similar concentration of prolamine was added to heparinized (5 U/ml) Krebs perfusate. Left ventricular developed pressure, maximum rate of pressure rise, and heart rate declined significantly (p < 0.01) in hearts exposed to protamine only (65.0% +/- 6.6%, 55.5% +/- 6.0%, and 87.6% +/- 2.5% of baseline, respectively), whereas protamine added to heparinized perfusate caused little change in developed pressure, maximum rate of pressure rise, and heart rate (85.3% +/- 5.4%, 84.9% +/- 5.5%, and 98.8% +/- 1.6%). To study systemic effects of protamine, we measured hemodynamic parameters in 12 heparinized dogs (150 U/kg). During protamine infusion (1.5 mg/kg intravenously over 30 seconds), mean blood pressure decreased by 46% +/- 7% from baseline (P < 0.05), cardiac output decreased by 38% +/- 4% (p < 0.05), and systemic vascular resistance decreased bv by 14& +/- 9%. After hemodynamic stabilization, Ng-monomethyl-L-arginine (2 mg/kg), a competitive inhibitor of nitric oxide synthesis, was administered to six dogs, and methylene blue (2 mg/kg), an inhibitor of cyclic guanosine monophosphate synthesis, was administered to the remaining six dogs. After treatment with Ng-monomethyl-L-arginine and methylene blue, the second infusion of protamine sulfate caused no significant change in blood pressure or cardiac output. In an additional six dogs, Ng-monomethyl-L-arginine pretreatment (5 mg/kg) blocked the effects of the first dose of protamine. The effect of Ng-monomethyl-L-arginine could be reversed by the addition of (6 mg/kg) L-arginine but not D-arginine.

CONCLUSIONS

Protamine-heparin complex does not cause direct myocardial depression but does lead to severe hypotension in vivo. The finding that hypotension can be blocked by inhibitors of the nitric oxide pathway confirms previous in vitro studies indicating that the effects of protamine are mediated, in part, by the vascular endothelium. Further, these studies suggest a novel approach to prevention of hemodynamic complications caused by heparin reversal after cardiopulmonary bypass.

Single doses of intravenous protamine result in the formation of protamine-specific IgE and IgG antibodies

BACKGROUND

Protamine reactions are a well-recognized and serious complication of intravenous protamine administration. IgE-mediated anaphylaxis occurs after initial sensitization and subsequent re-exposure to antigens. Subcutaneous protamine in insulin preparations is associated with protamine-specific IgE and IgG antibody production. In contrast, the influence of intravenous protamine administration on protamine-specific IgE and IgG antibody formation has never been investigated.

METHODS

Sera from 93 patients were analyzed for protamine-specific IgE and IgG antibodies both before and 4 to 6 weeks after exposure to single doses of intravenous protamine. Specific clinical variables were assessed by univariate and multivariate analyses to determine independent predictors of protamine-specific antibody production.

RESULTS

In patients who were previously seronegative, intravenous protamine administration resulted in protamine-specific IgE and IgG antibody production in 17 of 93 (18%) and 15 of 93 (16%) patients, respectively. As determined by multivariate analysis, male gender (p = 0.06) and insulin-dependent diabetes mellitus (p = 0.002) were associated with protamine-specific IgG but not IgE antibody production.

CONCLUSION

Single-dose intravenous protamine resulted in protamine-specific IgE and/or IgG antibody production in 26 of 93 (28%) of patients. Seroconversion was associated with male gender and insulin-dependent diabetes mellitus. Patients responding immunologically to protamine may be at increased risk for experiencing reactions on subsequent exposure.

Allergic reactions to fish

A wide variety of fish are known to induce allergic reactions following ingestion or inhalation of vapors by sensitized individuals. Although the exact prevalence of fish sensitivity is not known, fish are among the most important food allergens; and as consumption of fish increases, rates of sensitization are expected to increase. Diagnosis of fish allergy is aided by clinical history, skin prick testing, and in vitro assays; however, double-blind placebo-controlled food challenges are the most reliable method to confirm fish allergy and to identify putative species. It appears from RAST inhibition and SDS-PAGE/Western blot studies that the current policy of recommending that fish-sensitive individuals avoid all species of fish should be reevaluated. The major allergen in codfish (Gad cI) is one of the most extensively studied of all allergens. It is a calcium-chelating protein, with a mol wt of 12,328 kDa and an isoelectric point of 4.75. As an allergen, Gad cI is very stable and its allergenic activity appears to be dependent on amino acid sequence. Crossreactivity among some fish species may be the result of common structures within related proteins.

Protamine-induced permeability changes in the neutrophil plasma membrane as the basis of activation of exocytosis

Protamine induces a gradual change in plasma membrane permeability in rabbit neutrophils, which is evident from the increase of indol fluorescence, and the leakage of quin2 from quin2-loaded neutrophils. The influx of extracellular Ca2+ into the neutrophil provides an explanation for exocytosis which occurs in the presence of Ca2+ and protamine. The dependence of exocytosis on Ca2+ concentration follows the same pattern as is observed in neutrophils permeabilized by other means. In the absence of Ca2+, and in the presence of protamine, La3+ has an activating effect on exocytosis. At higher concentrations La3+ inhibits exocytosis that occurs in the presence of Ca2+ and protamine, as do some other metal ions. The resemblance between the membrane effects of a number of toxins, as reported in literature, and protamine-induced membrane damage suggests that they occur via the same mechanism.

Carboxypeptidase N concentration during cardiopulmonary bypass in humans

Carboxypeptidase N (CPN) is an inactivator of anaphylatoxins and kinins, peptides implicated in the pathogenesis of complications in extracorporeal circulation. To investigate whether the level of CPN is altered during cardiopulmonary bypass (CPB) we studied 15 patients undergoing cardiac surgery utilizing CPB. The concentration of CPN decreased to about 48% of the initial value upon initiation of CPB and remained low throughout the procedure. A similar decrease was observed in the level of alkaline phosphatase, an enzyme that was measured to assess the degree of haemodilution. When the data were normalized for dilution, no difference in the concentration of CPN was observed during CPB. Moreover, no changes in the concentration of CPN were observed when protamine was given to neutralize heparin and none of the 15 patients experienced any side-effects of protamine administration. We conclude that the decrease in CPN during CPB was due primarily to dilution and not to changes in CPN synthesis or catabolism. Protamine administration is not associated with significant changes in the level of CPN in patients who have an asymptomatic reversal of heparin anticoagulation.

Allergy to protamine

Recent advances in medicine, such as cardiac catheterization, phoresis, dialysis, and cardiopulmonary bypass technology, have increased the need for heparin anticoagulation. To antagonize heparin's effect and prevent hemorrhagic complications after the procedure, protamine has likewise been used more frequently. With its increased use have come increased reports of adverse protamine reactions consisting of rash, urticaria, elevation of pulmonary artery pressure, systemic hypotension, and, at times, death. The elevation of pulmonary artery pressure, which appears to be a rather common occurrence in animals, may be an isolated finding without clinical consequences in humans. However, this pulmonary vasoconstriction may, when severe, lead to acute right-sided heart failure and systemic hypotension. Other protamine reactions involve a decrease in systemic vascular resistance and systemic hypotension without changes in pulmonary artery pressure. Causes of acute protamine reactions may involve the generation of anaphyatoxins and prostanoids either from protamine-heparin complexes or complement-fixing antiprotamine IgG antibodies, from inhibition of plasma Carboxypeptidase N, from crosslinking of cell-surface antiprotamine IgE on mast cells and basophils with subsequent mediator release, or from potentiation of IgE-mediated release of histamine through a polycationin-recognition site. Although we have come a long way in understanding the mechanisms by which protamine can cause its ill effects in humans, more work is clearly needed to define, in prospective studies, the incidence of and risk factors for protamine reactions in various patient groups, and to delineate more clearly which mechanisms are involved in each clinical type of acute protamine reaction. Hopefully, this will lead to strategies and protamine alternatives that will prevent or diminish, in frequency or severity, adverse protamine reactions. Alternatively, a clearer picture of the risk factors important for protamine reactions and the predictive value of diagnostic tests (e.g., protamine IgE antibody) can also minimize the clinical impact of this increasingly common adverse event.

Serial immunological investigations in a patient who had a life-threatening reaction to intravenous protamine

Reactions to intravenous protamine include rash, urticaria, bronchospasm, hypotension, and/or pulmonary artery pressure elevation. We have previously shown that in diabetic patients receiving daily protamine-insulin injections, the presence of anti-protamine IgE or IgG antibodies are significant risk factors for acute, life-threatening reactions when protamine is given intravenously. To study protamine reactions further, we measured serum anti-protamine IgE and IgG antibody levels, in-vitro basophil histamine release and intracutaneous skin testing to protamine serially in an NPH-insulin dependent diabetic who had a severe, protracted anaphylactic reaction to protamine. At the time of his protamine reaction, his serum contained 8.5 ng/ml of anti-protamine IgE and 1.3 micrograms/ml of anti-protamine IgG antibody. One month following the reaction both anti-protamine IgE and IgG increased to 16 ng/ml (twofold rise) and 90.5 micrograms/ml (70-fold rise), respectively. With time, both anti-protamine IgE and IgG antibody declined. Serial intradermal skin tests using protamine sulphate did not discriminate between the protamine reactor and nine normal control subjects who had no prior exposure nor any demonstrable serum IgE antibody to protamine. In-vitro basophil histamine release to protamine sulphate was inconclusive in discriminating between the protamine reactor and normal control subjects. We postulate that protamine may be an incomplete or univalent antigen that must first combine with a tissue macromolecule or possibly heparin to become a complete multivalent antigen capable of eliciting IgE antibody-dependent mediator release.

A prospective study of the risk of an immediate adverse reaction to protamine sulfate during cardiopulmonary bypass surgery

Protamine sulfate administration may cause life-threatening reactions. We prospectively examined the incidence of immediate adverse reaction after protamine in 243 patients who underwent cardiopulmonary bypass surgery. Twenty-six patients (10.7%) had reactions, and 1.6% had a precipitous drop in blood pressure immediately after protamine administration. Risk factors were previous exposure to protamine, diabetes, history of receiving protamine-containing insulin, and possibly vasectomy. However, neither a positive skin test nor a positive IgE ELISA for antiprotamine antibody predicted that a patient would have a reaction. C4a levels were increased in patients who had reactions as compared with age-, sex-, and cardiac disease-matched patients who did not have reactions, suggesting a role for complement in some reactions. Immediate adverse reactions to protamine are very common, and alternative therapies are urgently needed to eliminate the use of protamine.

Lack of cross-reactivity between IgE to salmon and protamine sulfate

Immediate type-generalized reactions to protamine sulfate are uncommon but may be fatal. The mechanisms of severe or fatal reactions are unknown in most cases. One theory is that contaminating fish (salmon) proteins present in protamine solutions induce anaphylaxis in salmon-sensitive subjects. A second hypothesis is that protamine interacts with anti-salmon IgE to cause anaphylaxis. We assessed these hypotheses by establishing an indirect amplified enzyme-linked immunosorbent assay (ELISA) for IgE to salmon. Sera obtained from two subjects anaphylactically sensitive to salmon demonstrated high binding to salmon that was not inhibited by preincubation of sera with 500 or 1000 micrograms of protamine or Aspergillus fumigatus. Serum from a patient who experienced anaphylactic shock from protamine was indistinguishable from control sera in the ELISA for IgE to salmon. Anti-protamine IgE could not be demonstrated in separate experiments. The assays prove that 1) serum IgE to salmon is not inhibited by protamine and 2) serum from a patient experiencing a severe reaction to protamine did not contain IgE to salmon or protamine. The experiments do not support the notion that there is cross-reactivity between IgE to salmon and protamine sulfate in the cases evaluated.

Association of protamine IgE and IgG antibodies with life-threatening reactions to intravenous protamine

Life-threatening reactions to intravenous protamine, administered to reverse heparin anticoagulation, have been reported with increasing frequency as a consequence of the escalating use of cardiac catheterization and coronary bypass surgery. Retrospective studies have shown that such reactions are more common in diabetic patients receiving daily subcutaneous injections of protamine-insulin preparations. To determine whether anti-protamine IgE or IgG antibodies might explain the increased risk for protamine reactions among patients with protamine-insulin-dependent diabetes, we conducted a case-control study of 27 patients (diabetic and nondiabetic) who had acute reactions to intravenous protamine and 43 diabetic patients who tolerated protamine without a reaction during diagnostic or surgical procedures. Cases and controls were grouped according to previous exposure to protamine-insulin preparations. In diabetic patients who had received protamine-insulin injections, the presence of serum antiprotamine IgE antibody was a significant risk factor for acute protamine reactions (relative risk, 95; P = 1.0 X 10(-5), as was antiprotamine IgG (relative risk, 38; P = 1.2 X 10(-5). No patients without previous exposure to protamine-insulin injections had serum protamine IgE antibodies. In this group, anti-protamine IgG antibody was a risk factor for protamine reactions (relative risk, 25; P = 0.0062). We conclude that in protamine-insulin-dependent diabetics, the increased risk of serious reactions when intravenous protamine was given appeared to be caused largely by antibody-mediated mechanisms. In nondiabetic subjects, the presence of protamine IgG was significantly associated with an increased risk of acute protamine reactions, although many nondiabetic subjects who had reactions had no IgG antibodies.

Protamine sulfate and fatal anaphylactoid shock

A 73-year-old male underwent uneventful three-vessel coronary artery bypass grafting after which he received iv protamine sulfate for reversal of systemic heparinization. Shortly thereafter, the patient developed and succumbed to an anaphylactoid reaction attributed to protamine. The patient had none of the previously reported risk factors for hypersensitivity to the drug and was therefore not considered at high risk for such a severe adverse reaction. Although uncommon, the fatal outcome of this low-risk patient seriously addresses the need for alternative measures for heparin reversal.

Efficacy and safety of outpatient cardiac catheterization

Outpatient cardiac catheterization has become the standard in our laboratory. The only exclusion for outpatient study is current hospitalization for cardiac symptoms. Thus, any patient well enough to be at home is studied on an outpatient basis. We reviewed our experience on 4,094 diagnostic studies of which 3,537 (86%) were done on a same-day basis. The complication rates were generally lower than in published series with a mortality of 0.05%. There were no admissions for late bleeding. Ninety-seven percent of the procedures were done by the percutaneous technique utilizing 7-French catheters. Patients were heparinized, and protamine was not used. The low complication rate is to a large extent due to meticulous postoperative care by critical care nurses in an outpatient observation unit contiguous to the laboratory. Outpatient cardiac catheterization is a safe, cost-saving approach applicable to a large majority of cardiac patients.