Systemic anaphylaxis--separation of cardiac reactions from respiratory and peripheral vascular events

Pathophysiological, Cellular, and Molecular Events of the Vascular System in Anaphylaxis

Anaphylaxis is a systemic hypersensitivity reaction that can be life threatening. Mechanistically, it results from the immune activation and release of a variety of mediators that give rise to the signs and symptoms of this pathological event. For years, most of the research in anaphylaxis has focused on the contribution of the immune component. However, approaches that shed light on the participation of other cellular and molecular agents are necessary. Among them, the vascular niche receives the various signals (e.g., histamine) that elicit the range of anaphylactic events. Cardiovascular manifestations such as increased vascular permeability, vasodilation, hypotension, vasoconstriction, and cardiac alterations are crucial in the pathophysiology of anaphylaxis and are highly involved to the development of the most severe cases. Specifically, the endothelium, vascular smooth muscle cells, and their molecular signaling outcomes play an essential role downstream of the immune reaction. Therefore, in this review, we synthesized the vascular changes observed during anaphylaxis as well as its cellular and molecular components. As the risk of anaphylaxis exists both in clinical procedures and in routine life, increasing our knowledge of the vascular physiology and their molecular mechanism will enable us to improve the clinical management and how to treat or prevent anaphylaxis.

Key Message

Anaphylaxis, the most severe allergic reaction, involves a variety of immune and non-immune molecular signals that give rise to its pathophysiological manifestations. Importantly, the vascular system is engaged in processes relevant to anaphylactic events such as increased vascular permeability, vasodilation, hypotension, vasoconstriction, and decreased cardiac output. The novelty of this review focuses on the fact that new studies will greatly improve the understanding of anaphylaxis when viewed from a vascular molecular angle and specifically from the endothelium. This knowledge will improve therapeutic options to treat or prevent anaphylaxis.

Kounis Syndrome—not a Single-organ Arterial Disorder but a Multisystem and Multidisciplinary Disease

Coronary symptoms associated with conditions related to mast cell activation and inflammatory cell interactions, such as those involving T-lymphocytes and macrophages, further inducing allergic, hypersensitivity, anaphylactic, or anaphylactic insults, are currently referred to as the Kounis syndrome. Kounis syndrome is caused by inflammatory mediators released during allergic insults, post-inflammatory cell activation, and interactions via multidirectional stimuli. A platelet subset of 20% with high- and low-affinity IgE surface receptors is also involved in this process. Kounis syndrome is not just a single-organ but also a complex multisystem and multi-organ arterial clinical condition; it affects the coronary, mesenteric, and cerebral arteries and is accompanied by allergy–hypersensitivity–anaphylaxis involving the skin, respiratory, and vascular systems in the context of anesthesia, surgery, radiology, oncology, or even dental and psychiatric medicine; further, it has significantly influences both morbidity and mortality. Kounis syndrome might be caused by numerous and continuously increasing causes, with broad clinical symptoms and signs, via multi-organ arterial system involvement, in patients of any age, thereby demonstrating predominant anaphylactic features in terms of a wide spectrum of mast cell-association disorders. Cardiac symptoms, such as chest pain, coronary vasospasm, angina pectoris, myocardial infarction, stent thrombosis, acute cardiac failure, and sudden cardiac death associated with subclinical, clinical, acute, or chronic allergic reactions, constitute the clinical manifestations of this syndrome. Since its first description, a common pathway between allergic and non-allergic coronary events has been demonstrated. The hypothesis is based on the existence of a much higher degree of mast cell degranulation at plaque erosion or rupture sites compared with at the adjacent areas or even more distant segments in post-acute myocardial infarction of non-allergic etiology. Although mast cell activation, differentiation, and mediator release takes days or weeks, the mast cell degranulation may occur just before any acute coronary event, further resulting in coronary artery vasoconstriction and atheromatous plaque rupture. It seems that medications and natural molecules stabilizing the mast cell membrane as well as monoclonal antibodies protecting the mast cell surface can emerge as novel therapeutic modalities for acute coronary and cerebrovascular event prevention.

Anaphylactic cardiovascular collapse and Kounis syndrome: systemic vasodilation or coronary vasoconstriction?

The first reported human anaphylactic death is considered to be the Pharaoh Menes death, caused by a wasp sting. Currently, anaphylactic cardiovascular events represent one of most frequent medical emergencies. Rapid diagnosis, prompt and appropriate treatment can be life saving. The main concept beyond anaphylaxis lies to myocardial damage and ventricular dysfunction, thus resulting in cardiovascular collapse. Cardiac output depression due to coronary hypoperfusion from systemic vasodilation, leakage of plasma and volume loss due to increased vascular permeability, as well as reduced venous return, are regarded as the main causes of cardiovascular collapse. Clinical reports and experiments indicate that the human heart, in general, and the coronary arteries, in particular, could be the primary target of the released anaphylactic mediators. Coronary vasoconstriction and thrombosis induced by the released mediators namely histamine, chymase, tryptase, cathepsin D, leukotrienes, thromboxane and platelet activating factor (PAF) can result to further myocardial damage and anaphylaxis associated acute coronary syndrome, the so-called Kounis syndrome. Kounis syndrome with increase of cardiac troponin and other cardiac biomarkers, can progress to heart failure and cardiovascular collapse. In experimental anaphylaxis, cardiac reactions caused by the intracardiac histamine and release of other anaphylactic mediators are followed by secondary cardiovascular reactions, such as cardiac arrhythmias, atrioventricular block, acute myocardial ischemia, decrease in coronary blood flow and cardiac output, cerebral blood flow, left ventricular developed pressure (LVdp/dtmax) as well as increase in portal venous and coronary vascular resistance denoting vascular spasm. Clinically, some patients with anaphylactic myocardial infarction respond satisfactorily to appropriate interventional and medical therapy, while anti-allergic treatment with antihistamines, corticosteroids and fluid replacement might be ineffective. Therefore, differentiating the decrease of cardiac output due to myocardial tissue hypoperfusion from systemic vasodilation and leakage of plasma, from myocardial tissue due to coronary vasoconstriction and thrombosis might be challenging during anaphylactic cardiac collapse. Combined antiallergic, anti-ischemic and antithrombotic treatment seems currently beneficial. Simultaneous measurements of peripheral arterial resistance and coronary blood flow with newer diagnostic techniques including cardiac magnetic resonance imaging (MRI) and myocardial scintigraphy may help elucidating the pathophysiology of anaphylactic cardiovascular collapse, thus rendering treatment more rapid and effective.

Coronary spasm secondary to cefuroxime injection, complicated with cardiogenic shock - a manifestation of Kounis syndrome: case report and literature review

Kounis syndrome is defined as the coincidental occurrence of an acute coronary syndrome with hypersensitivity reactions following an allergic event. The three reported variants of Kounis syndrome are vasospastic allergic angina, allergic myocardial infarction and stent thrombosis with occluding thrombus. The syndrome is caused by various inflammatory mediators. The pathophysiological characteristics of Kounis syndrome involve coronary artery spasm and/or atheromatous plaque erosion or rupture during an allergic reaction. Several causes have been described to induce Kounis syndrome, and their number is increasing rapidly. The haemodynamic effect of the syndrome complicated by cardiogenic shock seems to combine allergic shock with extensive peripheral vasodilation and myocardial suppression with the characteristics of cardiogenic shock. Treatment of Kounis syndrome is challenging because it needs management of both cardiac and allergic manifestation simultaneously. We present a case report of type I Kounis syndrome, with coronary spasm secondary to cefuroxime injection complicated with cardiogenic shock. A brief review of the literature on the various facets of this condition is also provided.

Combined etiology of anaphylactic cardiogenic shock: amiodarone, epinephrine, cardioverter defibrillator, left ventricular assist devices and the Kounis syndrome

Anaphylactic shock is a life-threatening condition which needs detailed and mediculous clinical assessment and thoughtful treatment. Several causes can join forces in order to degranulate mast cells. Amiodarone which is an iodine-containing highly lipophilic benzofuran can induce allergic reactions and anaphylactic shock in sensitized patients. Epinephrine is a life saving drug, but in sulfite allergic patients it should be given with caution due its metabisulfite preservative. Metals covering cardiac defibrillators and pacemakers can act as antigens attached to serum proteins and induce allergic reactions. In anaphylactic shock, myocardial involvement due to vasospasm-induced coronary blood flow reduction manifesting as Kounis syndrome should be always considered. Clinically, combined treatment targeting the primary cause of anaphylaxis together with protection of cardiac tissue seems to be of paramount importance.

Anaphylactic shock after amiodarone infusion resulting in haemodynamic collapse requiring a temporary ventricular assist device

Acute heart failure related to anaphylactic shock is often reversible and necessitates aggressive support to ensure full recovery. We report the case of a 15-year-old boy who developed severe ventricular dysfunction and haemodynamic instability after administration of amiodarone and required temporary mechanical circulatory support with a left ventricular assist device. He had full recovery of cardiac function and returned to baseline neurologic status. This is the first report of successful left ventricular assist device use for recovery from cardiovascular collapse due to anaphylaxis.

Mouse anaphylactic shock is caused by reduced cardiac output, but not by systemic vasodilatation or pulmonary vasoconstriction, via PAF and histamine

AIMS

Systemic anaphylaxis is life-threatening, and its pathophysiology is not fully clarified. Mice are frequently used for experimental study on anaphylaxis. However, the hemodynamic features and mechanisms of mouse anaphylactic hypotension remain unknown. Therefore, we determined mechanisms of systemic and pulmonary vascular response to anaphylactic hypotension in anesthetized BALB/c mice by using receptor antagonists of chemical mediators.

MAIN METHODS

Anaphylaxis was actively induced by an intravenous injection of the ovalbumin antigen into open-chest artificially ventilated sensitized mice. Mean arterial pressure (MAP), pulmonary arterial pressure (PAP), left atrial pressure, central venous pressure, and aortic blood flow (ABF) were continuously measured.

KEY FINDINGS

In sensitized control mice, MAP and ABF showed initial, transient increases, followed by progressive decreases after the antigen injection. Total peripheral resistance (TPR) did not decrease, while PAP initially and transiently increased to 18.5±0.5mmHg and pulmonary vascular resistance (PVR) also significantly increased. The antigen-induced decreases in MAP and ABF were attenuated by pretreatment with either a platelet-activating factor (PAF) receptor antagonist, CV6209, or a histamine H1 receptor antagonist, diphenhydramine, and were abolished by their combination. Diphenhydramine augmented the initial increases in PAP and PVR, but did not affect the decrease of the corresponding MAP fall. The antagonists of either leukotriene C4 or serotonin, alone or in combination with CV6209, exerted no significant effects.

SIGNIFICANCE

Mouse anaphylactic hypotension is caused by a decrease in cardiac output but not vasodilatation, via actions of PAF and histamine. The slight increase in PAP is not involved in mouse anaphylactic hypotension.

The more allergens an atopic patient is exposed to, the easier and quicker anaphylactic shock and Kounis syndrome appear: Clinical and therapeutic paradoxes

Kounis syndrome is a condition that combines allergic, hypersensitivity, anaphylactic or anaphylactoid reactions with acute coronary syndromes including vasospastic angina, acute myocardial infarction and stent thrombosis. This syndrome is a ubiquitous disease affecting patients of any age, involving numerous and continuously increasing causes, with broadening clinical manifestations and covering a wide spectrum of mast cell activation disorders. Drugs, environmental exposures and various conditions are the main offenders. Clinical and therapeutic paradoxes concerning Kounis syndrome therapy, pathophysiology, clinical course and causality have been encountered during its clinical course. Drugs that counteract allergy, such as H2-antihistamines, can induce allergy and Kounis syndrome. The more drugs an atopic patient is exposed to, the easier and quicker anaphylaxis and Kounis syndrome can occur. Every anesthetized patient is under the risk of multiple drugs and substances that can induce anaphylactic reaction and Kounis syndrome. The heart and the coronary arteries seem to be the primary target in severe anaphylaxis manifesting as Kounis syndrome. Commercially available adrenaline saves lives in anaphylaxis but it contains as preservative sodium metabisulfite and should be avoided in the sulfite allergic patients. Thus, careful patient past history and consideration for drug side effects and allergy should be taken into account before use. The decision to prescribe a drug where there is a history of previous adverse reactions requires careful assessment of the risks and potential benefits.

Anaphylactic Shock: Kounis Hypersensitivity-Associated Syndrome Seems to be the Primary Cause

Experiments have shown that anaphylaxis decreases cardiac output; increases left ventricular end diastolic pressure; induces severe early acute increase in respiratory resistance with pulmonary interstitial edema; and decreases splanchnic, cerebral, and myocardial blood flow more than what would be expected from severe arterial dilation and hypotension. This is attributed to the constrictive action of inflammatory mediators released during anaphylactic shock. Inflammatory mediators such as histamine, neutral proteases, arachidonic acid products, platelet-activating factor (PAF), and a variety of cytokines and chemokines constitute the pathophysiologic basis of Kounis hypersensitivity-associated acute coronary syndrome. Although the mechanisms of anaphylactic shock still remain to be elucidated, myocardial involvement due to vasospasm-induced coronary blood flow reduction manifesting as Kounis syndrome should be always considered. Searching current experimental and clinical literature on anaphylactic shock pathophysiology, causality, clinical appearance, and treatment via PubMed showed that differentiating global hypoperfusion from primary tissue suppression due to mast cell mediator constrictive action on systemic arterial vasculature is a challenging procedure. Combined tissue suppression from arterial involvement and peripheral vasodilatation, perhaps, occur simultaneously. In cases of anaphylactic shock treatment targeting the primary cause of anaphylaxis together with protection of coronary vasculature and subsequently the cardiac tissue seems to be of paramount importance.

Immune responses and hypercoagulation in ERT for Pompe disease are mutation and rhGAA dose dependent

Enzyme replacement therapy (ERT) with recombinant human acid-α-glucosidase (rhGAA) is the only FDA approved therapy for Pompe disease. Without ERT, severely affected individuals (early onset) succumb to the disease within 2 years of life. A spectrum of disease severity and progression exists depending upon the type of mutation in the GAA gene (GAA), which in turn determines the amount of defective protein produced and its enzymatic activity. A large percent of the early onset patients are also cross reactive immunological material negative (CRIM-) and develop high titer immune responses to ERT with rhGAA. New insights from our studies in pre-clinical murine models reveal that the type of Gaa mutation has a profound effect on the immune responses mounted against ERT and the associated toxicities, including activation of clotting factors and disseminated intravascular coagulation (DIC). Additionally, the mouse strain affects outcomes, suggesting the influence of additional genetic components or modifiers. High doses of rhGAA (20 mg/kg) are currently required to achieve therapeutic benefit. Our studies indicate that lower enzyme doses reduce the antibody responses to rhGAA, reduce the incidence of immune toxicity and avoid ERT-associated anaphylaxis. Therefore, development of rhGAA with increased efficacy is warranted to limit immunotoxicities.

Brain injury due to anaphylactic shock: broadening manifestations of Kounis syndrome

Anaphylactic shock is a real and life threatening medical emergency which is encountered in every field of medicine. The coronary arteries seem to be the primary target of anaphylaxis resulting in the development of Kounis syndrome. Kounis syndrome is a pan-arterial anaphylaxis -associated syndrome affecting patients of any age, involving numerous and continuously increasing causes, with broadening clinical manifestations and covering a wide spectrum of mast cell activation disorders. Recently, Kounis-like syndrome affecting the cerebral arteries was found to be associated with mast cell activation disorders. In anaphylactic shock, the decrease of cerebral blood flow is more than what would be expected from severe arterial hypotension. This is attributed to the early and direct action of anaphylactic mediators on cerebral vessels. While adrenaline is a life saving agent in the treatment of anaphylactic shock, it contains sodium betabisulfite as preservative and should be avoided in sulfite allergic patients. Potential allergens encountered in endodotic practice include formocresol, zinc compounds thiurams, sodium dimethyldithiocarbamade, and mercaptobenzothiazole that might have synergistic action. All these agents together with analgesics, antibiotics, antiseptics, formaldehyde, latex, local anaesthetics and metals used in dental practice, in general, can induce anaphylactic shock. Practitioners should be aware of these consequences. A careful history of previous atopy and reactions is of paramount importance for safe and effective management.

Coronary hypersensitivity disorder: the Kounis syndrome

BACKGROUND

When allergy or hypersensitivity and anaphylactic or anaphylactoid insults lead to cardiovascular symptoms and signs, including acute coronary events, the result might be the recently defined nosologic entity Kounis syndrome. Vasospastic allergic angina, allergic myocardial infarction, and stent thrombosis with occluding thrombus infiltrated by eosinophils and/or mast cells are the 3 reported variants of this syndrome.

OBJECTIVE

The purpose of this review was to highlight and consolidate the recent literature on allergic angina and allergic myocardial infarction and to propose new therapeutic modalities for stabilizing mast cells.

METHODS

A search for current literature on the pathophysiology, causality, clinical appearance, variance, prevention, and treatment of Kounis syndrome was conducted.

RESULTS

Kounis syndrome is caused by inflammatory mediators such as histamine; neutral proteases, including tryptase, chymase, and cathepsin-D; arachidonic acid products; platelet-activating factor; and a variety of cytokines and chemokines released during the mast-cell activation. Platelets with Fc γ receptor (FcγR) Ι, FcγRII, FcεRI, and FcεRII also have a role in the activation cascade. The same mediators released from the similar inflammatory cells are involved in acute coronary events of nonallergic etiology. These cells are not only present in the involved region before plaque erosion or rupture but also release their contents just before an acute coronary event. Pro-inflammatory mediators similar to those found in Kounis syndrome are found in some cases with nonallergic etiology, suggesting that this is a more general problem. The acute coronary and cerebrovascular events in Kounis syndrome may be prevented by the inhibition of mast-cell degranulation. Substances and natural molecules that protect the mast-cell surface and stabilize the mast-cell membrane are emerging as novel agents in the prevention of acute coronary and other arterial events.

CONCLUSIONS

The 3 reported variants of Kounis syndrome-vasospastic allergic angina, allergic myocardial infarction, and stent thrombosis with occluding thrombus-are caused by inflammatory mediators. Agents that inhibit mast-cell degranulation may be efficacious in preventing the acute coronary and cerebrovascular events of Kounis syndrome.

Kounis syndrome: a new twist on an old disease

Kounis syndrome is the concurrence of acute coronary syndromes with conditions associated with mast cell activation, such as allergies or hypersensitivity and anaphylactic or anaphylactoid insults that can involve other interrelated and interacting inflammatory cells behaving as a 'ball of thread'. It is caused by inflammatory mediators such as neutral proteases including tryptase and chymase, arachidonic acid products, histamine, platelet activating factor and a variety of cytokines and chemokines released during the activation process. Platelets with FCεRI and FCεRII receptors also participate in the above cascade. Vasospastic allergic angina, allergic myocardial infarction and stent thrombosis with occluding thrombus infiltrated by eosinophils and/or mast cells constitute the three reported variants of this syndrome. Kounis syndrome is a ubiquitus disease that represents a magnificent natural paradigm and nature's own experiment, in a final trigger pathway implicated in cases of coronary artery spasm and plaque rupture. Kounis syndrome can complicate anesthesia, vaccination, medical therapy and stent implantation and it seems to be associated with coronary allograft vasculopathy and takotsubo syndrome, it can often be confused with hypersensitivity myocarditis and can be the cause of unexplained sudden death. Kounis syndrome has revealed that the same mediators released from the same inflammatory cells are present in acute coronary events of nonallergic etiology. These cells are not only present in the culprit region before plaque erosion or rupture but they release their contents just before an actual coronary event. Therefore, does Kounis syndrome represent a magnificent natural paradigm and nature's own experiment in a final trigger pathway implicated in cases of coronary artery spasm and plaque rupture showing a novel way towards our effort to prevent acute coronary syndromes? Drugs, substances targeting the stem cell factor that is essential for mast cell development, proliferation, survival, adhesion and homing as well as monoclonal antibodies and natural molecules that protect mast cell surface and stabilize mast cell membrane could emerge as novel therapeutic ways capable to prevent acute coronary and acute cerebrovascular events.

Demographic and clinical characteristics of patients with anaphylactic shock after surgery for cystic echinococcosis

We reviewed the records of 446 patients who were treated surgically for cystic echinococcosis (CE) to identify risk factors for anaphylactic shock. Of 446 patients, 10 had final diagnoses of anaphylactic shock induced by CE; none died. The incidence of anaphylactic shock was significantly higher in younger age groups (P < 0.001) and in patients with pulmonary cysts. Anaphylactic shock induced by CE appears to differ from type I immediate hypersensitivity shock, which suggests that in CE, shock may be caused by a combination of immediate hypersensitivity and endotoxic shock. This possibility suggests that additional precautions should be taken during surgery. These precautions include reducing intracystic pressure, which would prevent possible leaked liquid from reaching other organs by surrounding the cyst with sterile gauze and decrease the chance of spreading the echinococcus; preventing antigen from contacting other tissues where it might trigger anaphylaxis; and resecting the cyst completely when feasible.

Sphingosine kinase 1 and sphingosine-1-phosphate receptor 2 are vital to recovery from anaphylactic shock in mice

Sphingosine kinase 1 (SphK1) and SphK2 are ubiquitous enzymes that generate sphingosine-1-phosphate (S1P), a ligand for a family of G protein-coupled receptors (S1PR1-S1PR5) with important functions in the vascular and immune systems. Here we explore the role of these kinases and receptors in recovery from anaphylaxis in mice. We found that Sphk2-/- mice had a rapid recovery from anaphylaxis. In contrast, Sphk1-/- mice showed poor recovery from anaphylaxis and delayed histamine clearance. Injection of S1P into Sphk1-/- mice increased histamine clearance and promoted recovery from anaphylaxis. Adoptive cell transfer experiments demonstrated that SphK1 activity was required in both the hematopoietic and nonhematopoietic compartments for recovery from anaphylaxis. Mice lacking the S1P receptor S1PR2 also showed a delay in plasma histamine clearance and a poor recovery from anaphylaxis. However, S1P did not promote the recovery of S1pr2-/- mice from anaphylaxis, whereas S1pr2+/- mice showed partial recovery. Unlike Sphk2-/- mice, Sphk1-/- and S1pr2-/- mice had severe hypotension during anaphylaxis. Thus, SphK1-produced S1P regulates blood pressure, histamine clearance, and recovery from anaphylaxis in a manner that involves S1PR2. This suggests that specific S1PR2 agonists may serve to counteract the vasodilation associated with anaphylactic shock.

The Pathophysiology of Shock in Anaphylaxis

The balance of evidence from human observations and animal studies suggests that the main pathophysiologic features of anaphylactic shock are a profound reduction in venous tone and fluid extravasation causing reduced venous return (mixed hypovolemic-distributive shock) and depressed myocardial function. Aggressive fluid resuscitation is required to ameliorate hypovolemic-distributive shock, and an intravenous infusion of epinephrine will increase vascular tone, myocardial contractility, and cardiac output in most cases. Where these measures fail, pathophysiologic considerations and anecdotal evidence support the consideration of selective vasoconstrictors as the next step in treatment.

Penicillin allergy in cancer patients manifesting as Kounis syndrome

Two cases of allergic angina and allergic myocardial infarction (Kounis syndrome) following penicillin administration are described. The patients suffered from lung and mandible neoplasms and had previously received several courses of antineoplastic therapy without any sequelae. One patient had normal coronary arteries (type I variant of the syndrome) and the other had coronary artery disease with previous myocardial infarction (type II variant of the syndrome). The allergic reaction following penicillin administration seemed to have triggered the development of an acute coronary artery spasm in the first patient and an acute myocardial infarction in the second. This report shows that susceptible individuals expressing a magnified mast cell degranulation effect may be more vulnerable to coronary artery spasm and plaque erosion or rupture.

Kounis syndrome (allergic angina and allergic myocardial infarction): a natural paradigm?

Inflammatory mediators including histamine, neutral proteases, arachidonic acid products, platelet activating factor and a variety of cytokines and chemokines are increased in blood or urine in both allergic episodes and acute coronary syndromes. The release of mediators during allergic insults has been incriminated to induce coronary artery spasm and/or atheromatous plaque erosion or rupture. A common pathway between allergic and non-allergic coronary syndromes seems to exist. Today, there is evidence that mast cells not only enter the culprit region before plaque erosion or rupture but they release their contents before an actual coronary episode. Kounis syndrome is the concurrence of acute coronary syndromes with conditions associated with mast cell activation including allergic or hypersensitivity and anaphylactic or anaphylactoid insults. It is caused by inflammatory mediators released through mast cell activation. Kounis syndrome, as consequence, of the above pathophysiologic association is regarded as nature's own experiment and magnificent natural paradigm showing novel way in an effort to prevent acute coronary syndromes. Drugs and natural molecules which stabilize mast cell membrane and monoclonal antibodies that protect mast cell surface could emerge as novel therapeutic modalities capable to prevent acute coronary and cerebrovascular events.

An anaphylactic reaction possibly associated with an intraoperative coronary artery spasm during general anesthesia

We report a case of anaphylactic reaction occurring during general anesthesia that may have been accompanied by a coronary artery spasm. The present case and a review of the medical literature suggest that coronary artery spasm is evoked by common vasoactive mediators with anaphylactic reactions. Coronary artery spasm should be counted as a symptom of the cardiovascular manifestation of anaphylaxis. Clinicians should be aware of this possible complication when treating an anaphylactic reaction, especially in patients at risk for atherosclerosis. Early recognition of ST segment elevation is essential for diagnosis and treatment of coronary artery spasm.

Effects of histamine H1-receptor blockade on respiratory and cardiac manifestation of systemic anaphylaxis

In vivo anaphylaxis is associated with respiratory distress and cardiovascular failure. The present investigation was designed to further characterize respiratory and cardiac anaphylactic events. In guinea pigs, sensitization was produced by subcutaneous application of ovalbumin together with Freund's adjuvant. Fourteen days after sensitization, the effects of an intravenous infusion of ovalbumin were tested in the anesthetized artificially ventilated guinea pigs. The renewed application of the antigen induced an initial increase of left ventricular pressure which was followed by a rapid decrease 5 min after antigenic challenge. Enddiastolic left ventricular pressure increased within 3 min, thus indicating left ventricular pump failure. In the same time range, ECG recordings uniformly showed signs of acute myocardial ischemia. In addition, heart rate steadily decreased. All animals died within 15 min. Simultaneously with cardiac anaphylactic malfunction, severe arterial hypoxia and carbon dioxide retention occurred, revealing respiratory distress. Histamine is known as a potent bronchoconstrictor via histamine H1-receptor stimulation. Administration of H1-receptor antagonists to improve respiration may therefore provide further information on the contribution of pulmonary malfunction to anaphylactic cardiovascular shock. Therefore, additional experiments were performed with sensitized guinea pigs pretreated with the histamine H1-receptor blocker mepyramine. In these experiments the antigenic challenge induced a dissociation of cardiac and respiratory manifestation of anaphylaxis. Despite inhibition of hypoxia and carbon dioxide retention, left ventricular pump failure and occurrence of myocardial ischemia were delayed but not suppressed. It is concluded that histamine is an important mediator of anaphylactic respiratory distress. However, vasoactive anaphylactic mediators other than histamine are primarily involved in anaphylactic cardiac malfunction occurring during the later phase of systemic anaphylaxis.

Effects of histamine H1- and H2-receptor antagonists on cardiovascular function during systemic anaphylaxis in guinea pigs

The heart is a target organ of anaphylaxis. In isolated perfused hearts, an anaphylactic reaction is characterized by arrhythmias, coronary constriction and severe impairment of ventricular contractile force. Various mediators such as PAF, thromboxane A2 and leukotrienes are responsible for anaphylactic coronary constriction and negative inotropic effects. The cardiac effects of anaphylactic histamine release are related to the stimulation of two antagonistic receptor types. Histamine induces atrioventricular conduction delay and constriction of the epicardial coronary vessels via H1-receptor stimulation. H2-receptors, however, mediate coronary vasodilation and an increase in heart rate and myocardial contractility. It may therefore be concluded that administration of histamine H2-receptor antagonists is disadvantageous. During anaphylactic states, the cardiodepressive effects of the other mediators of anaphylaxis are unmasked, resulting in a sustained coronary constriction and impairment of myocardial contractility. To verify this speculation, we investigated the effects of H1- and H2-receptor antagonists on cardiovascular function of guinea pigs during systemic anaphylaxis. In guinea pigs, sensitization was produced by subcutaneous application of ovalbumin. Fourteen days after sensitization, the effects of an intravenous infusion of ovalbumin were tested in the anesthetized artificially ventilated guinea pigs. The renewed administration of the antigen induced severe cardiac dysfunction. Within a few minutes, cardiac output markedly decreased and left ventricular end-diastolic pressure increased significantly, indicating left ventricular pump failure. In the same time range, ECG recordings uniformly showed signs of acute myocardial ischemia. In addition, arrhythmias occurred in terms of an atrioventricular block.(ABSTRACT TRUNCATED AT 400 WORDS)