Histamine provocation of clinical coronary artery spasm: implications concerning pathogenesis of variant angina pectoris

Effectiveness of histamine receptor antagonists in the treatment of histamine-driven clinical symptoms: do we have a histamine or, better, an anti-histamine problem?

Why are up to 50% of patients with chronic urticaria resistant to antihistamines? Why do many patients with indolent systemic mastocytosis suffer severe symptoms despite treatment with four times the approved antihistamine doses? Do millions of patients with atopic diseases and related disorders have a histamine or, better, an antihistamine problem? If one carefully analyzes human clinical studies with exogenous histamine challenge and endogenous mast cell activation with prophylactic antihistamine pretreatment, the assumed efficacy of antihistamines rapidly fades. Local tissue free drug concentrations of many antihistamines are <100 nM compared with 10-1000 µM possible extracellular local histamine concentrations after mast cell activation. Is the pharmaceutical industry aware of this problem?

IgE and cardiac disease

IgE acts primarily via the high affinity IgE receptor (FcεRI) and is central to immediate hypersensitivity reactions (anaphylaxis). However, IgE is also important in the development of chronic hypersensitivity reactions (allergy). In the cardiovascular system, numerous clinical studies have investigated serum IgE levels, mainly in the context of myocardial infarction, and have established a clear association between IgE and ischemic cardiac events. While animal studies demonstrate that IgE can cause atherosclerotic plaque formation, this is complicated by clinical reports that IgE is associated with non-fatal ischemic events and not with fatal events, raising the possibility that IgE could be protective in this setting. In terms of non-ischemic cardiac disease, little information is available clinically for IgE; however, animal models also indicate that IgE promotes adverse effects in this setting as well. This review article will present the clinical studies that have established a relationship between serum IgE levels and cardiac disease, particularly myocardial infarction. This review article will also discuss animal studies that provide mechanistic understanding of how IgE can exert chronic effects in the heart. This article also attempts to address the question of whether IgE is causative of cardiac disease or is a response to cardiac disease.

The Effect of Iodinated Contrast Media Sensitivity on the Prognosis of Patients with STEMI

Background and Objectives: Iodinated Contrast Media (ICM) is used daily in many imaging departments worldwide. The main risk associated with ICM is hypersensitivity. When a severe hypersensitivity reaction is not properly managed and treated swiftly, it may be fatal. Currently, there is no data to demonstrate how ICM sensitivity affects the prognosis of cardiac patients, especially those diagnosed with ST elevation myocardial infarction (STEMI), in whom urgent coronary angiography is indicated. This study aimed to identify and characterize this relationship. Materials and Methods: We included patients hospitalized with STEMI between 2016 and 2019 from the National Inpatient Sample. The population was compared based on ICM sensitivity status, sensitive vs. non-sensitive. The primary endpoint was in-hospital mortality, with additional endpoints: length of stay and in-hospital complications. Results: The study included 664,620 STEMI patients, of whom 4905 (0.7%) were diagnosed with ICM sensitivity. ICM-sensitive patients were older, more often white, females, and had more comorbidities and cardiovascular risk factors. Both groups show similarities in management but are slightly less probable to undergo PCI or CABG. Multivariable logistic regression models found that the ICM-sensitive population had similar odds of in-hospital mortality (OR: 1.02, 95% CI: 0.89-1.16) and MACCE (OR: 1.05, 95% CI: 0.95-1.16), and less major bleeding (OR: 0.73, 95% CI: 0.60-0.87). Conclusions: Our study found that ICM sensitivity status was not a significant factor for worse prognosis in patients hospitalized with STEMI.

An Insight into Kounis Syndrome: Bridging Clinical Knowledge with Forensic Perspectives

Kounis syndrome (KS) is an acute coronary syndrome triggered by allergic or hypersensitivity reactions. Incidence rates vary, with studies reporting 19.4 per 100.000 among all admissions and 3.4% among allergy patients. This review explores the expanding understanding of KS, encompassing various manifestations, and focusing on both clinical data and forensic findings useful in performing a diagnosis. The pathophysiology of this syndrome involves a complex interplay between allergic reactions and the cardiovascular system. Mast cell activation, histamine release, leukotrienes, cytokines, and platelet activation can contribute to coronary events. Three types of classification systems (allergic angina, allergic myocardial infarction, allergic stent thrombosis) aid in categorizing presentations. The diagnosis of KS relies on clinical presentation, laboratory findings, and imaging. Postmortem assessment of KS is based on the integration of circumstantial data, autopsy, and histological findings. Biochemical and immunohistochemical analyses also contribute to postmortem diagnosis. In conclusion, a combined, multidisciplinary approach should be used to ease the diagnostic process, which is crucial for forensic practitioners in confirming KS occurrence.

A Heart Gone Bananas: Allergy-Induced Coronary Vasospasm due to Banana (Kounis Syndrome)

Kounis syndrome encompasses a variety of cardiovascular signs and symptoms associated with mast cell activation in the setting of allergic or hypersensitivity and anaphylactic or anaphylactoid insults. It can manifest as coronary vasospasm, coronary, or in-stent thrombosis, and acute myocardial infarction with plaque rupture. Various medications as well as foods including fish, shellfish, mushroom, kiwi, and rice pudding have been implicated as causal agents. We present what we believe to be the first documented case of Kounis syndrome manifesting as coronary vasospasm as the result of an allergy to banana. This case highlights the importance of considering allergic causes of angina and allergy referral in a patient with known atopy and an otherwise negative cardiovascular workup. It also emphasizes to consider food allergy, especially banana, as a cause of Kounis syndrome.

Function and Role of Histamine H1 Receptor in the Mammalian Heart

Histamine can change the force of cardiac contraction and alter the beating rate in mammals, including humans. However, striking species and regional differences have been observed. Depending on the species and the cardiac region (atrium versus ventricle) studied, the contractile, chronotropic, dromotropic, and bathmotropic effects of histamine vary. Histamine is present and is produced in the mammalian heart. Thus, histamine may exert autocrine or paracrine effects in the mammalian heart. Histamine uses at least four heptahelical receptors: H1, H2, H3 and H4. Depending on the species and region studied, cardiomyocytes express only histamine H1 or only histamine H2 receptors or both. These receptors are not necessarily functional concerning contractility. We have considerable knowledge of the cardiac expression and function of histamine H2 receptors. In contrast, we have a poor understanding of the cardiac role of the histamine H1 receptor. Therefore, we address the structure, signal transduction, and expressional regulation of the histamine H1 receptor with an eye on its cardiac role. We point out signal transduction and the role of the histamine H1 receptor in various animal species. This review aims to identify gaps in our knowledge of cardiac histamine H1 receptors. We highlight where the published research shows disagreements and requires a new approach. Moreover, we show that diseases alter the expression and functional effects of histamine H1 receptors in the heart. We found that antidepressive drugs and neuroleptic drugs might act as antagonists of cardiac histamine H1 receptors, and believe that histamine H1 receptors in the heart might be attractive targets for drug therapy. The authors believe that a better understanding of the role of histamine H1 receptors in the human heart might be clinically relevant for improving drug therapy.

Successful Use of Continuous Erector Spinae Plane Blocks in a Patient With Variant Angina After Large Ventral Hernia Repair

Coronary artery spasm constitutes the primary underlying pathology of variant angina. Because provocation of coronary artery spasm may occur with both excess sympathetic and excess parasympathetic stimulation, patients with this disorder have extremely limited options for perioperative pain control. This is especially true for procedures involving extensive abdominal incision/manipulation. Whereas neuraxial analgesia might otherwise be appropriate in these cases, several studies have demonstrated that coronary artery spasm can occur as a result of epidural placement, and therefore, that this may not be an optimal choice for patients with variant angina. This report discusses the case of a patient with a preexisting diagnosis of variant angina who underwent an exploratory laparotomy with large ventral hernia repair and for whom continuous erector spinae plane blocks were successfully used as analgesic adjuncts without triggering coronary artery spasm.

A Possibility of Vasospastic Angina after mRNA COVID-19 Vaccination

We report a case of vasospastic angina (VSA) following COVID-19 mRNA vaccination. Despite the widespread occurrence of myocarditis, there have been few reports of post-vaccinal VSA. A 41-year-old male patient was referred for chest pain at rest following mRNA vaccination; he had never experienced chest pain prior to vaccination. He was diagnosed by an acetylcholine (Ach) provocation test that showed multivessel vasospasm. After the initiation of treatment with a calcium channel blocker and nitrate, no further exacerbation of chest pain was observed. To our knowledge, this constitutes the first reported case of VSA proven by Ach provocation test after COVID-19 vaccination. The vaccination may increase coronary artery spasticity. VSA should be ruled out in post-vaccine new onset resting chest pain.

Cellular Mechanisms of Coronary Artery Spasm

Coronary artery spasm (CAS) is a reversible phenomenon caused by spontaneous excessive vascular smooth muscle contractility and vascular wall hypertonicity, which results in partial or complete closure of the lumen of normal or atherosclerotic coronary arteries. The clinical picture of CAS includes chest discomfort which is similar in quality to that of stable effort angina. Mechanisms underlying the development of CAS are still unclear. CAS certainly is a multifactorial disease. In this review, we paid attention to the role of the main pathophysiologic mechanisms in CAS: endothelial dysfunction, chronic inflammation, oxidative stress, smooth muscle hypercontractility, atherosclerosis and thrombosis, and mutations leading to deficient aldehyde dehydrogenase 2 (ALDH2) activity. These findings might shed novel insight on the underlying mechanisms and identify potential diagnostic and therapeutic targets for cardiovascular diseases in the future.

Diamine oxidase knockout mice are not hypersensitive to orally or subcutaneously administered histamine

OBJECTIVE

To evaluate the contribution of endogenous diamine oxidase (DAO) in the inactivation of exogenous histamine, to find a mouse strain with increased histamine sensitivity and to test the efficacy of rhDAO in a histamine challenge model.

METHODS

Diamine oxidase knockout (KO) mice were challenged with orally and subcutaneously administered histamine in combination with the β-adrenergic blocker propranolol, with the two histamine-N-methyltransferase (HNMT) inhibitors metoprine and tacrine, with folic acid to mimic acute kidney injury and treated with recombinant human DAO. Core body temperature was measured using a subcutaneously implanted microchip and histamine plasma levels were quantified using a homogeneous time resolved fluorescence assay.

RESULTS

Core body temperature and plasma histamine levels were not significantly different between wild type (WT) and DAO KO mice after oral and subcutaneous histamine challenge with and without acute kidney injury or administration of HNMT inhibitors. Treatment with recombinant human DAO reduced the mean area under the curve (AUC) for core body temperature loss by 63% (p = 0.002) and the clinical score by 88% (p < 0.001). The AUC of the histamine concentration was reduced by 81%.

CONCLUSIONS

Inactivation of exogenous histamine is not driven by enzymatic degradation and kidney filtration. Treatment with recombinant human DAO strongly reduced histamine-induced core body temperature loss, histamine concentrations and prevented the development of severe clinical symptoms.

The Roles of Cardiovascular H2-Histamine Receptors Under Normal and Pathophysiological Conditions

This review addresses pharmacological, structural and functional relationships among H₂-histamine receptors and H₁-histamine receptors in the mammalian heart. The role of both receptors in the regulation of force and rhythm, including their electrophysiological effects on the mammalian heart, will then be discussed in context. The potential clinical role of cardiac H₂-histamine-receptors in cardiac diseases will be examined. The use of H₂-histamine receptor agonists to acutely increase the force of contraction will be discussed. Special attention will be paid to the potential role of cardiac H₂-histamine receptors in the genesis of cardiac arrhythmias. Moreover, novel findings on the putative role of H₂-histamine receptor antagonists in treating chronic heart failure in animal models and patients will be reviewed. Some limitations in our biochemical understanding of the cardiac role of H₂-histamine receptors will be discussed. Recommendations for further basic and translational research on cardiac H₂-histamine receptors will be offered. We will speculate whether new knowledge might lead to novel roles of H₂-histamine receptors in cardiac disease and whether cardiomyocyte specific H₂-histamine receptor agonists and antagonists should be developed.

Histamine receptors in heart failure

The biogenic amine, histamine, is found predominantly in mast cells, as well as specific histaminergic neurons. Histamine exerts its many and varied actions via four G-protein-coupled receptors numbered one through four. Histamine has multiple effects on cardiac physiology, mainly via the histamine 1 and 2 receptors, which on a simplified level have opposing effects on heart rate, force of contraction, and coronary vasculature function. In heart failure, the actions of the histamine receptors are complex, the histamine 1 receptor appears to have detrimental actions predominantly in the coronary vasculature, while the histamine 2 receptor mediates adverse effects on cardiac remodeling via actions on cardiomyocytes, fibroblasts, and even endothelial cells. Conversely, there is growing evidence that the histamine 3 receptor exerts protective actions when activated. Little is known about the histamine 4 receptor in heart failure. Targeting histamine receptors as a therapeutic approach for heart failure is an important area of investigation given the over-the-counter access to many compounds targeting these receptors, and thus the relatively straight forward possibility of drug repurposing. In this review, we briefly describe histamine receptor signaling and the actions of each histamine receptor in normal cardiac physiology, before describing in more detail the known role of each histamine receptor in adverse cardiac remodeling and heart failure. This includes information from both clinical studies and experimental animal models. It is the goal of this review article to bring more focus to the possibility of targeting histamine receptors as therapy for heart failure.

Human histamine H2 receptors can initiate cardiac arrhythmias in a transgenic mouse

Histamine is known to lead to arrhythmias in the human heart. A mouse model to mimic these effects has hitherto not been available but might be useful to study the mechanism(s) of H₂-histamine receptor-induced arrhythmias and may support the search for new antiarrhythmic drugs. In order to establish such a model in mice, we studied here the incidence of cardiac arrhythmias under basal and under stimulated conditions in atrial and ventricular preparations from mice that overexpressed the human H₂-histamine receptors in a cardiac-specific way (H₂-TG) in comparison with their wild-type (WT) littermate controls. We had shown before that histamine exerted concentration and time-dependent positive inotropic and positive chronotropic effects only in cardiac preparations from H₂-TG and not from WT. We noted under basal conditions (no drug addition) that right atrial preparations from H₂-TG exhibited more spontaneous arrhythmias than right atrial preparations from WT. These arrhythmias in H₂-TG could be blocked by the H₂-histamine receptor antagonist cimetidine. In a similar fashion, histamine and dimaprit (an agonist at H₂ and not H₁-histamine receptors) more often induced arrhythmias in right atrial preparations from H₂-TG than from WT. To understand better the signal transduction mechanism(s) involved in these arrhythmias, we studied partially depolarized left atrial preparations. In these preparations, a positive inotropic effect of histamine was still present in the additional presence of 44 mM potassium ions (used to block sodium channels) in H₂-TG but not WT and this positive inotropic effect could be blocked by cimetidine and this is consistent with the involvement of calcium ion channels in the contractile and thus might mediate also the arrhythmogenic effects of histamine in H₂-TG. However, compounds reported to release histamine from cells and thereby leading to arrhythmias in humans, namely morphine, ketamine, and fentanyl, failed to induce a more pronounced positive inotropic effect in atrial preparations from H₂-TG compared to WT, arguing against an involvement of histamine release in their proarrhythmic side effects in patients. Measuring left ventricular contractility in isolated retrogradely perfused hearts (Langendorff mode), we detected under basal conditions (no drug application) more spontaneous arrhythmias in hearts from H₂-TG than from WT. In summary, we noted that overexpression of human H₂-histamine receptors in a novel transgenic animal model can lead to arrhythmias. We suggest that this model might be useful to understand the mechanism(s) of histamine-induced cardiac arrhythmias in humans better in a molecular way and may be of value to screen novel antiarrhythmic drugs.

Coronary Artery Spasm: The Interplay Between Endothelial Dysfunction and Vascular Smooth Muscle Cell Hyperreactivity

Patients with angina pectoris, the cardinal symptom of myocardial ischaemia, yet without significant flow-limiting epicardial artery stenosis represent a diagnostic and therapeutic challenge. Coronary artery spasm (CAS) is an established cause for anginal chest pain in patients with angiographically unobstructed coronary arteries. CAS may occur at the epicardial level and/or in the microvasculature. Although the underlying pathophysiological mechanisms of CAS are still largely unclear, endothelial dysfunction and vascular smooth muscle cell (VSMC) hyperreactivity seem to be involved as major players, although their contribution to induce CAS is still seen as controversial. This article will look at the role and possible mechanistic interplay between an impaired endothelial and VSMC function in the pathogenesis of CAS.

An autopsy case of sudden unexpected death with loxoprofen sodium-induced allergic eosinophilic coronary periarteritis

Although the cause of eosinophilic coronary periarteritis (ECPA) remains unclear, an allergic background is present in fewer patients than expected. A 50-year-old man with no history of allergy or symptoms suggestive of cardiac or respiratory disorders suddenly died shortly after oral administration of loxoprofen sodium. Autopsy showed eosinophilic coronary periarteritis in three main branches of the coronary arteries, characterized by eosinophil-predominant inflammation without fibrinoid necrosis or granulomatous change in the adventitia and its surroundings of the three main branches of the coronary arteries, in addition to the localized sign of bronchial asthma in the lung. Immunohistochemical examination showed that many mast cells positive for human mast cell tryptase were evident in the perivascular tissue containing peripheral nerve trunks. Whereas the blood concentration of loxoprofen sodium was within the therapeutic range, significant elevation of the serum histamine and tryptase levels was found. The present case suggests that eosinophilic coronary periarteritis may be caused by a type I allergic reaction in some patients and that loxoprofen sodium can trigger a life-threatening type I allergic reaction, including eosinophilic coronary periarteritis, leading to sudden unexpected death.

Is chronic urticaria more than skin deep?

Chronic urticaria is a disease characterized by the appearance of weals, angioedema or both longer than 6 weeks. Degranulation of cutaneous or submucosal mast cells leads to release of mediators including histamine resulting in redness, swelling and itch. Because mast cells are widely distributed throughout the body, the question is why they are not activated systemically or does systemic activation occur without overt end organ dysfunction? We have conducted an exploratory literature search for reports that have evidence of organ-specific dysfunction in chronic urticaria that might justify prospective observational studies. This search revealed some evidence of systemic effects of chronic urticaria in cardiac, respiratory, gastrointestinal, central nervous and musculo-skeletal systems. The relevance of these findings needs to be further determined. However, they justify prospective studies in larger numbers of patients and at different stages of disease activity.

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.

Stress cardiomyopathy: Is it limited to Takotsubo syndrome? Problems of definition

In 2006, Takotsubo syndrome (TTC) was described as a distinct type of stress-induced cardiomyopathy (stress cardiomyopathy). However, when thinking about Takotsubo cardiomyopathy from the viewpoints of the AHA and ESC classifications, 2 possible problems may arise. The first potential problem is that a forecast of disease outcome is lacking in the ESC classification, whereas the AHA only states that 'outcome is favorable with appropriate medical therapy'. However, based on the literature data, one can make a general conclusion that occurrence of myocardial lesions in TTC (i.e., myocardial fibrosis and contraction-band necrosis) causes the same effects as in other diseases with similar levels of myocardial damage and should not be considered to have a lesser impact on mortality. To summarise, TTC can cause not only severe complications such as pulmonary oedema, cardiogenic shock, and dangerous ventricular arrhythmias, but also damage to the myocardium, which can result in the development of potentially fatal conditions even after the disappearance of LV apical ballooning. The second potential problem arises from the definition of TTC as a stress cardiomyopathy in the AHA classification. In fact, the main factors leading to TTC are stress and microvascular anginas, since, as has been already discussed, coronary spasm can cause myocardium stunning, resulting in persistent apical ballooning. Thus, based on this review, 3 distinct types of stress cardiomyopathies exist (variant angina, microvascular angina, and TTC), with poor prognosis. Adding these diseases to the classification of cardiomyopathies will facilitate diagnosis and preventive prolonged treatment, which should include intensive anti-stress therapy.

Reversible Pharmacological Induction of Motor Symptoms in MPTP-Treated Mice at the Presymptomatic Stage of Parkinsonism: Potential Use for Early Diagnosis of Parkinson's Disease

A crucial event in the pathogenesis of Parkinson's disease is the death of dopaminergic neurons of the nigrostriatal system, which are responsible for the regulation of motor function. Motor symptoms first appear in patients 20-30 years after the onset of the neurodegeneration, when there has been a loss of an essential number of neurons and depletion of compensatory reserves of the brain, which explains the low efficiency of treatment. Therefore, the development of a technology for the diagnosing of Parkinson's disease at the preclinical stage is of a high priority in neurology. In this study, we have developed at an experimental model a fundamentally novel for neurology approach for diagnosis of Parkinson's disease at the preclinical stage. This methodology, widely used for the diagnosis of chronic diseases in the internal medicine, is based on the application of a challenge test that temporarily increases the latent failure of a specific functional system, thereby inducing the short-term appearance of clinical symptoms. The provocation test was developed by a systemic administration of α-methyl-p-tyrosine (αMpT), a reversible inhibitor of tyrosine hydroxylase to MPTP-treated mice at the presymptomatic stage of parkinsonism. For this, we first selected a minimum dose of αMpT, which caused a decrease of the dopamine level in the striatum of normal mice below the threshold at which motor dysfunctions appear. Then, we found the maximum dose of αMpT at which a loss of dopamine in the striatum of normal mice did not reach the threshold level, and motor behavior was not impaired. We showed that αMpT at this dose induced a decrease of the dopamine concentration in the striatum of MPTP-treated mice at the presymptomatic stage of parkinsonism below a threshold level that results in the impairment of motor behavior. Finally, we proved that αMpT exerts a temporal and reversible influence on the nigrostriatal dopaminergic system of MPTP-treated mice with no long-term side effects on other catecholaminergic systems. Thus, the above experimental data strongly suggest that αMpT-based challenge test might be considered as the provocation test for Parkinson's disease diagnosis at the preclinical stage in the future clinical trials.

Airborne Pollen Concentrations and Emergency Room Visits for Myocardial Infarction: A Multicity Case-Crossover Study in Ontario, Canada

Few studies have examined the acute cardiovascular effects of airborne allergens. We conducted a case-crossover study to evaluate the relationship between airborne allergen concentrations and emergency room visits for myocardial infarction (MI) in Ontario, Canada. In total, 17,960 cases of MI were identified between the months of April and October during the years 2004-2011. Daily mean aeroallergen concentrations (pollen and mold spores) were assigned to case and control periods using central-site monitors in each city along with daily measurements of meteorological data and air pollution (nitrogen dioxide and ozone). Odds ratios and their 95% confidence intervals were estimated using conditional logistic regression models adjusting for time-varying covariates. Risk of MI was 5.5% higher (95% confidence interval (CI): 3.4, 7.6) on days in the highest tertile of total pollen concentrations compared with days in the lowest tertile, and a significant concentration-response trend was observed (P < 0.001). Higher MI risk was limited to same-day pollen concentrations, with the largest risks being observed during May (odds ratio = 1.16, 95% CI: 1.00, 1.35) and June (odds ratio = 1.10, 95% CI: 1.00, 1.22), when tree and grass pollen are most common. Mold spore concentrations were not associated with MI. Our findings suggest that airborne pollen might represent a previously unidentified environmental risk factor for myocardial infarction.

Enhanced p122RhoGAP/DLC-1 Expression Can Be a Cause of Coronary Spasm

Background

We previously showed that phospholipase C (PLC)-δ1 activity was enhanced by 3-fold in patients with coronary spastic angina (CSA). We also reported that p122Rho GTPase-activating protein/deleted in liver cancer-1 (p122RhoGAP/DLC-1) protein, which was discovered as a PLC-δ1 stimulator, was upregulated in CSA patients. We tested the hypothesis that p122RhoGAP/DLC-1 overexpression causes coronary spasm.

Methods and Results

We generated transgenic (TG) mice with vascular smooth muscle (VSM)-specific overexpression of p122RhoGAP/DLC-1. The gene and protein expressions of p122RhoGAP/DLC-1 were markedly increased in the aorta of homozygous TG mice. Stronger staining with anti-p122RhoGAP/DLC-1 in the coronary artery was found in TG than in WT mice. PLC activities in the plasma membrane fraction and the whole cell were enhanced by 1.43 and 2.38 times, respectively, in cultured aortic vascular smooth muscle cells from homozygous TG compared with those from WT mice. Immediately after ergometrine injection, ST-segment elevation was observed in 1 of 7 WT (14%), 6 of 7 heterozygous TG (84%), and 7 of 7 homozygous TG mice (100%) (p<0.05, WT versus TGs). In the isolated Langendorff hearts, coronary perfusion pressure was increased after ergometrine in TG, but not in WT mice, despite of the similar response to prostaglandin F_2α between TG and WT mice (n = 5). Focal narrowing of the coronary artery after ergometrine was documented only in TG mice.

Conclusions

VSM-specific overexpression of p122RhoGAP/DLC-1 enhanced coronary vasomotility after ergometrine injection in mice, which is relevant to human CSA.

The association of atopy with incidence of ischemic heart disease, stroke, and diabetes

Allergy is a systemic inflammatory disease that could theoretically affect the risk of cardiovascular disease (CVD) and diabetes through inflammatory pathways or mast cell-induced coronary spasm. Whether allergy is associated with an increased risk of CVD and diabetes is largely unknown. We investigated the association between atopy as assessed by IgE sensitization, a well-accepted biomarker of allergy, and incidence of ischemic heart disease, stroke, and diabetes in five Danish population-based cohorts. A total of 14,849 participants were included in the study. Atopy was defined as serum-specific IgE positivity to inhalant allergens. The Danish National Diabetes Register enabled identification of incident diabetes. Likewise, the Danish Registry of Causes of Death and the Danish National Patient Register provided information on fatal and non-fatal ischemic heart disease and stroke. Data were analyzed by Cox regression analyses with age as underlying time axis and adjusted for study cohort, gender, education, body mass index, alcohol intake, smoking habits, physical activity during leisure time, serum lipids, and blood pressure. The prevalence of atopy was 26.9 % (n = 3,994). There were 1,170, 817, and 1,063 incident cases of ischemic heart disease, stroke, and diabetes, respectively (median follow-up 11.2 years). The hazard ratios, HRs (95 % confidence intervals, CIs) for atopics versus non-atopics: for ischemic heart disease (HR 1.00, 95 % CI 0.86, 1.16), stroke (HR 1.18, 95 % CI 0.99, 1.41), and diabetes (HR 1.06, 95 % CI 0.91, 1.23). Our results did not support the hypothesis that atopy is associated with higher risk of ischemic heart disease, stroke, or diabetes. However, a small-moderately increased risk cannot be excluded from our data.

Coronary artery spasm following off-pump coronary artery bypass surgery

Coronary artery spasm after coronary artery bypass surgery may result in life-threatening arrhythmias, circulatory collapse, or death. We report two cases of coronary artery spasm after coronary artery bypass surgery, one of which developed ventricular fibrillation requiring extracorporeal membrane oxygenation support. Both patients were discharged in good condition and are currently followed as outpatients. Unexpected sudden hemodynamic compromise could be due to coronary vasospasm, and this should be considered as one of the possible differential diagnoses. We were able to prevent the lethal consequences seen with coronary artery spasm by early diagnosis and management.

Histamine blood concentration in ischemic heart disease patients

The aim of this study was to investigate histamine blood concentration in subjects suffering from different types of ischemic heart diseases during the period of eight days. Our results showed that the histamine blood level was associated with different types of ischemic heart diseases. The blood histamine level in all investigated patients was significantly higher when compared to control subjects (44.87 ± 1.09 ng mL⁻¹), indicating the increase of histamine release in patients suffering from coronary diseases. In patients suffering from ACS-UA and ACS-STEMI, the second day peak of histamine level occurs (90.85 ± 6.34 ng mL⁻¹ and 121.7 ± 6.34 ng mL⁻¹, resp.) probably as the reperfusion event. Furthermore, our data suggest that histamine can be additional parameter of myocardial ischemia along with cardiac specific enzymes and may prove to be an excellent single prognostic marker for multitude of ischemic heart diseases.

Histamine 50-skin-prick test: a tool to diagnose histamine intolerance

Background. Histamine intolerance results from an imbalance between histamine intake and degradation. In healthy persons, dietary histamine can be sufficiently metabolized by amine oxidases, whereas persons with low amine oxidase activity are at risk of histamine toxicity. Diamine oxidase (DAO) is the key enzyme in degradation. Histamine elicits a wide range of effects. Histamine intolerance displays symptoms, such as rhinitis, headache, gastrointestinal symptoms, palpitations, urticaria and pruritus. Objective. Diagnosis of histamine intolerance until now is based on case history; neither a validated questionnaire nor a routine test is available. It was the aim of this trial to evaluate the usefullness of a prick-test for the diagnosis of histamine intolerance. Methods. Prick-testing with 1% histamine solution and wheal size-measurement to assess the relation between the wheal in prick-test, read after 20 to 50 minutes, as sign of slowed histamine degradation as well as history and symptoms of histamine intolerance. Results. Besides a pretest with 17 patients with HIT we investigated 156 persons (81 with HIT, 75 controls): 64 out of 81 with histamine intolerance(HIT), but only 14 out of 75 persons from the control-group presented with a histamine wheal ≥3 mm after 50 minutes (P < .0001). Conclusion and Clinical Relevance. Histamine-50 skin-prickt-test offers a simple tool with relevance.

Role of coronary vasoconstriction in ischemic heart disease and search for novel therapeutic targets

Atherothrombosis has long been recognized as an important mechanism of cardiac events in ischemic heart disease, and large multicenter clinical studies have shown the benefit of antiplatelet agents, statins, beta-blockers and angiotensin converting enzyme inhibitors in preventing these events. However, more recent studies have been less successful at showing incremental gains in targeting these mechanisms, suggesting that the limits of this strategy have been exploited. Coronary vasoconstriction is another important mechanism in ischemic heart disease but has received little attention and yet is a potential therapeutic target. In the current review, the reasons why coronary vasconstriction has received insufficient consideration are explored. In particular, we need to change our approach from lumping heterogeneous clinical entities together to focusing on clinically-discrete homogeneous groups with a common mechanism and thus therapeutic target. The role of coronary vasoconstriction is examined in the various ischemic syndromes (variant angina, chronic stable angina, acute coronary syndromes and syndrome X) and the underlying mechanisms discussed. Finally, in order to advance studies in this field, an innovative research strategy is proposed, including: (1) selection of paradigmatic cases for the various ischemic syndromes; (2) candidate therapeutic targets; and (3) approaches in assessing the clinical efficacy of these potential therapies.

Regulation of cardiac afferent excitability in ischemia

The heart at the time of Sir William Harvey originally was thought to be an insensate organ. Today, however, we know that this organ is innervated by sensory nerves that course centrally though mixed nerve pathways that also contain parasympathetic or sympathetic motor nerves. Angina or cardiac pain is now well recognized as a pressure-like pain that occurs during myocardial ischemia when coronary artery blood flow is interrupted. Sympathetic (or spinal) afferent fibers that are either finely myelinated or unmyelinated are responsible for the transmission of information to the brain that ultimately allows the perception of angina as well as activation of the sympathetic nervous system, resulting in tachycardia, hypertension, and sometimes arrhythmias. Although early studies defined the importance of the vagal and sympathetic cardiac afferent systems in reflex autonomic control, until recently there has been little appreciation of the mechanisms of activation of the sensory endings. This review examines the role of a number of chemical mediators and their sources that are activated by the ischemic process. In this regard, patients with ischemic syndromes, particularly myocardial infarction and unstable angina, are known to have platelet activation, which leads to release of a number of chemical mediators, including serotonin, histamine, and thromboxane A(2), all of which stimulate ischemically sensitive cardiac spinal afferent endings in the ventricles through specific receptor-mediated processes. Furthermore, protons from lactic acid, bradykinin, and reactive oxygen species, especially hydroxyl radicals, individually and frequently in combination, stimulate these endings during ischemia. Cyclooxygenase products appear to sensitize the endings to the action of bradykinin and histamine. These studies of the chemical mechanisms of activation of cardiac sympathetic afferent endings during ischemia have the potential to provide targeted therapies that can modify the angina and the deleterious reflex responses that have the potential to exacerbate ischemia and myocardial cell death.

Systemic Mastocytosis: Clinical Manifestations and Differential Diagnosis

Mast cells produce symptoms by local and remote effects of mediator release and by their presence in increased numbers in normal tissue and bone marrow, where they damage and impair normal organ function. Moreover, mast cells are long-lived and heterogeneous in their response to secretagogues and to inhibitors of mediator release. Clinicians sorting out the diagnosis of SM on the basis of presenting signs and symptoms continue to have their diagnostic skills challenged because of the rarity of this disorder, the fact that many symptoms of SM are present in more common disorders, and the multiple guises that SM may assume at the time of presentation.

An acid-sensing ion channel that detects ischemic pain

Ischemic pain occurs when there is insufficient blood flow for the metabolic needs of an organ. The pain of a heart attack is the prototypical example. Multiple compounds released from ischemic muscle likely contribute to this pain by acting on sensory neurons that innervate muscle. One such compound is lactic acid. Here, we show that ASIC3 (acid-sensing ion channel #3) has the appropriate expression pattern and physical properties to be the detector of this lactic acid. In rats, it is expressed only in sensory neurons and then only on a minority (approximately 40%) of these. Nevertheless, it is expressed at extremely high levels on virtually all dorsal root ganglion sensory neurons that innervate the heart. It is extraordinarily sensitive to protons (Hill slope 4, half-activating pH 6.7), allowing it to readily respond to the small changes in extracellular pH (from 7.4 to 7.0) that occur during muscle ischemia. Moreover, both extracellular lactate and extracellular ATP increase the sensitivity of ASIC3 to protons. This final property makes ASIC3 a "coincidence detector" of three molecules that appear during ischemia, thereby allowing it to better detect acidosis caused by ischemia than other forms of systemic acidosis such as hypercapnia.

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.

Is there a role for provocation testing to diagnose coronary artery spasm?

Spontaneous coronary artery spasm is an important cause of morbidity both in patients with coronary artery disease and in those with variant angina. A number of pharmacological agents have been identified which can provoke coronary artery spasm in susceptible patients. The role of provocation testing in the clinical diagnosis of coronary spasm is controversial. This is reflected by variations in the clinical use of provocation testing between specialist cardiac centres. Provocation testing appears to be a sensitive method of identifying patients with variant angina and active disease but such patients can often be diagnosed clinically. The specificity is less clear. There is little evidence that altering patient therapy on the basis of a positive test modifies prognosis. There may be a role for provocation testing in rare patients with refractory disease to identify a target site for coronary stenting. A more widespread use of these tests in patients with undiagnosed chest pain syndromes would not currently be recommended.

Involvement of CGRP in the inhibitory effect of rutaecarpine on vasoconstriction induced by anaphylaxis in guinea pig

Previous investigations have indicated that calcitonin gene-related peptide (CGRP), a principal transmitter in capsaicin-sensitive sensory nerves, could alleviate cardiac anaphylaxis injury. Rutaecarpine relaxes vascular smooth by stimulation of CGRP release via activation of vanilloid receptor subtype 1 (VR1). In the present study, we examined the role of capsaicin-sensitive sensory nerves in anaphylactic vessels and the effect of rutaecarpine on antigen-challenged constriction in the guinea pig isolated thoracic aorta. The aortas were challenged with 0.01 mg/ml bovine serum albumin, and the tension of aorta rings was continuously monitored. The amount of CGRP released from thoracic aortas was determined in the absence or presence of rutaecarpine. Antigen challenge caused a vasoconstrictor response concomitantly with an increase in the release of CGRP from the isolated thoracic aorta, and the vasoconstrictor responses were potentiated by CGRP8-37 (10 microM) or capsaicin (1 microM). Pretreatment with diphenhydramine (1 microM) markedly decreased antigen-challenged vasoconstriction. Acute application of capsaicin (0.03 or 0.1 microM) significantly inhibited vasoconstrictor responses. Pretreatment with rutaecarpine (10 or 30 microM) significantly increased CGRP release concomitantly with decrease in antigen-challenged vasoconstriction, which was abolished by CGRP8-37 (10 microM) or capsazepine (10 microM). The present results suggest that an increase in the release of CGRP during vascular anaphylaxis may be a beneficial compensatory response, and that rutaecarpine inhibits antigen-challenged vasoconstriction, which is related to stimulation of endogenous CGRP release via activation of VR1.

Acute ST-segment elevation myocardial infarction after amoxycillin-induced anaphylactic shock in a young adult with normal coronary arteries: a case report

Background

Acute myocardial infarction (MI) following anaphylaxis is rare, especially in subjects with normal coronary arteries. The exact pathogenetic mechanism of MI in anaphylaxis remains unclear.

Case presentation

The case of a 32-year-old asthmatic male with systemic anaphylaxis, due to oral intake of 500 mg amoxycillin, complicated by acute ST-elevation MI is the subject of this report. Following admission to the local Health Center and almost simultaneously with the second dose of subcutaneous epinephrine (0.2 mg), the patient developed acute myocardial injury. Coronary arteriography, performed before discharge, showed no evidence of obstructive coronary artery disease. In vivo allergological evaluation disclosed strong sensitivity to amoxycillin and the minor (allergenic) determinants of penicillin.

Conclusion

Acute ST-elevation MI is a rare but potential complication of anaphylactic reactions, even in young adults with normal coronary arteries. Coronary artery spasm appears to be the main causative mechanism of MI in the setting of "cardiac anaphylaxis". However, on top of the vasoactive reaction, a thrombotic occlusion, induced by mast cell-derived mediators and facilitated by prolonged hypotension, cannot be excluded as a possible contributory factor.

Histamine Contributes to Ischemia-Related Activation of Cardiac Spinal Afferents: Role of H1 Receptors and PKC

Myocardial ischemia activates cardiac spinal afferents that transmit the nociceptive information leading to chest pain and elicit excitatory cardiovascular reflexes. Previous studies have shown that histamine is increased in coronary sinus blood during myocardial ischemia and that this autacoid stimulates abdominal visceral afferents. The present investigation evaluated the role of endogenous histamine in stimulation of ischemically sensitive cardiac spinal afferents. Nerve activity of single-unit cardiac afferents was recorded from the left sympathetic chain or rami communicans (T2–T5) in anesthetized cats. Sixty-four cardiac afferents were identified. Injection (5–30 μg/kg) of histamine into the left atrium (LA) stimulated 7 ischemically sensitive cardiac afferents resulting in a significant increase in their activity in a dose-dependent manner. Also, LA injection of histamine (10 μg/kg) stimulated 7 of 8 ischemically insensitive cardiac spinal afferents. Administrations of 2-(3-chlorophenyl)histamine (250 μg/kg, LA), a specific H1 receptor agonist and histamine (10 μg/kg, LA), stimulated 9 other ischemically sensitive cardiac afferents (0.48 ± 0.10 to 1.40 ± 0.20 imp/s). In contrast, dimaprit (500 μg/kg, LA), an H2 receptor agonist, stimulated only one of the 9 afferents and thus did not alter their overall activity (0.40 ± 0.09 to 0.54 ± 0.09 imp/s). ( R)α-Methyl-histamine (500 μg/kg, LA), an H3 receptor agonist, did not stimulate any of the 9 afferents. Pyrilamine (300 μg/kg, iv), a selective H1 receptor antagonist, attenuated the activity of 8 afferents during 5 min of ischemia from 3.32 ± 0.38 to 1.87 ± 0.28 imp/s and abolished the response of 9 other cardiac afferents to histamine. Finally, administration of PKC-(19–36) (30 μg/kg, iv), a selective inhibitor of protein kinase C, attenuated the response of 8 cardiac afferents to histamine by 32%. These data indicate that endogenous histamine contributes to activation of cardiac sympathetic afferents during myocardial ischemia through H1 receptors and that the action of histamine on these cardiac afferents is partially dependent on the intracellular PKC pathway.

Th2 shift in juvenile muscular atrophy of distal upper extremity: a combined allergological and flow cytometric analysis

Juvenile muscular atrophy of the distal upper extremity (JMADUE) is considered to be a type of flexion myelopathy; however, we recently reported cases of JMADUE associated with airway allergy successfully treated by plasma exchange. To further characterize the allergo-immunological features of JMADUE, 11 consecutive JMADUE patients in the neurology clinic at Kyushu University Hospital were studied. Past and present together with family histories of common allergic disorders were investigated. Total serum IgE was measured by an enzyme linked immunosorbent assay (ELISA) and allergen-specific IgE by a liquid phase enzyme immunoassay. Intracellular interferon (IFN) gamma-, interleukin (IL)-4-, IL-5- and IL-13-producing T cells in peripheral blood were analyzed by flow cytometry. Data from 42 healthy subjects were used as controls for allergological studies. Flow cytometric data from 21 healthy subjects were also used for comparison. The patients exhibited significantly higher frequencies of coexisting airway allergies such as allergic rhinitis (p=0.0057) and pollinosis (p=0.0064), family histories of allergic disorders (p=0.0075), and mite antigen specific IgE (p=0.0361) compared with the healthy subjects. Patients with JMADUE had a significantly higher percentage of IFNgamma-IL-4+CD4+T cells (p=0.0017), but not IL-5- or IL-13-producing CD4+T cells, and a reduced intracellular IFNgamma/IL-4 ratio in CD4+T cells (p=0.002) compared to the controls. These findings suggest that JMADUE has a significant T helper 2 (Th2) shift, which may in part contribute to the development of spinal cord damage.

Increased immunoglobulin E response in acute coronary syndromes

The role of inflammation and mast cell activation has been implicated in atherosclerotic plaque destabilization and rupture. To investigate the role of immunoglobulin E (IgE) in acute coronary syndrome, a prospective clinical study was conducted in patients with acute myocardial infarction (AMI), unstable angina pectoris (UAP), stable angina pectoris (SAP), and healthy controls. IgE levels were serially measured and compared in consecutive patients with AMI (n = 16) and UAP (n = 14) on days 1, 3, 7, 21 after admission and 3 months later and only once in stable angina pectoris (n = 15) and healthy controls (n = 14). In addition, blood eosinophil and basophil levels on admission were measured in all groups and compared. Initial IgE levels determined at admission in patients with AMI, UAP, and SAP were significantly higher than levels in the control group (p = 0.002). Initial high IgE level in AMI on day 1 increased to a peak by day 7 (p = 0.024), then gradually decreased by day 21 and at 3 months (p = 0.052). High IgE level in UAP persisted by day 7 and gradually decreased by day 21 and 3 months (p = 0.037 and p = 0.018, respectively). Blood eosinophil count on admission was significantly higher in UAP than in the control group (p = 0.005). Basophil levels of both AMI and UAP groups on admission were found to be elevated as opposed to control group (p = 0.02 and p = 0.012, respectively). This study demonstrates that the level of IgE significantly increased during the acute phase of acute coronary syndromes and gradually decreased, supporting the role of acute inflammatory response and mast cell involvement in plaque rupture.

[Iodic allergic reaction with vasospasm occluded coronary during coronarography]

Coronary vasospasm is infrequent during anaphylaxis reaction. The authors describe a severe coronary spasm following iodine allergic reaction and then should to explain the physiopathology of this complication.

Asthma, beta-agonists, and development of congestive heart failure: results of the ABCHF study

BACKGROUND

Previous studies demonstrated an association between asthma and idiopathic dilated cardiomyopathy (IDCM), raising concerns regarding chronic beta-agonist inhaler use. The purpose of this investigation was to replicate that association.

METHODS AND RESULTS

We identified 67 patients with IDCM and 130 controls with predominately ischemic cardiomyopathy. Patients were administered a structured, detailed phone survey by blinded interviewers, and had chart abstractions performed. We had 80% power to detect an odds ratio (OR) > or = 2.6 for the relation of asthma and IDCM. A history of asthma was present in 19.4% v 12.3% for cases and controls respectively, OR, 1.72, (95% confidence interval [CI], 0.72, 4.09), P = .18. The duration of asthma was higher in cases: 32.3 (19.7) years v 13.8 (15.0) years (P = 0.007). With adjustment for confounders, multivariate analyses revealed no significant relations between asthma or beta-agonist use and the later development of IDCM.

CONCLUSIONS

It is unlikely that previously occurring asthma or beta-agonist use has a strong relationship to the development of IDCM; however, IDCM and atopic diseases may cluster in families, warranting further work into the genetic relations between atopy and IDCM.

Histamine--can it cause an acute coronary event?

Myocardial infarction (MI) occurring during the course of an allergic urticarial reaction in the absence of systemic hypotension has been rarely reported. This paper reports the case of a 28-year-old woman with no significant risk factors for coronary artery disease who presented with generalized urticaria associated with chest pain and had electrocardiographic and enzymatic evidence of an acute MI. Review of the literature suggests that local histamine release may induce spasm of the coronary vasculature, thus leading to myocardial ischemia and infarction.

Acid-sensing ion channel 3 matches the acid-gated current in cardiac ischemia-sensing neurons

Cardiac afferents are sensory neurons that mediate angina, pain that occurs when the heart receives insufficient blood supply for its metabolic demand (ischemia). These neurons display enormous acid-evoked depolarizing currents, and they fire action potentials in response to extracellular acidification that accompanies myocardial ischemia. Here we show that acid-sensing ion channel 3 (ASIC3), but no other known acid-sensing ion channel, reproduces the functional features of the channel that underlies the large acid-evoked current in cardiac afferents. ASIC3 and the native channel are both especially sensitive to pH, interact similarly with Ca(2+), and gate rapidly between closed, open, and desensitized states. Particularly important is the ability of ASIC3 and the native channel to open at pH 7, a value reached in the first few minutes of a heart attack. The steep activation curve suggests that the channel opens when four protons bind. We propose that ASIC3, a member of the degenerin channel (of Caenorhabditis elegans)/epithelial sodium channel family of ion channels, is the sensor of myocardial acidity that triggers cardiac pain, and that it might be a useful pharmaceutical target for treating angina.

Acid-sensing ion channel 3 matches the acid-gated current in cardiac ischemia-sensing neurons

Cardiac afferents are sensory neurons that mediate angina, pain that occurs when the heart receives insufficient blood supply for its metabolic demand (ischemia). These neurons display enormous acid-evoked depolarizing currents, and they fire action potentials in response to extracellular acidification that accompanies myocardial ischemia. Here we show that acid-sensing ion channel 3 (ASIC3), but no other known acid-sensing ion channel, reproduces the functional features of the channel that underlies the large acid-evoked current in cardiac afferents. ASIC3 and the native channel are both especially sensitive to pH, interact similarly with Ca(2+), and gate rapidly between closed, open, and desensitized states. Particularly important is the ability of ASIC3 and the native channel to open at pH 7, a value reached in the first few minutes of a heart attack. The steep activation curve suggests that the channel opens when four protons bind. We propose that ASIC3, a member of the degenerin channel (of Caenorhabditis elegans)/epithelial sodium channel family of ion channels, is the sensor of myocardial acidity that triggers cardiac pain, and that it might be a useful pharmaceutical target for treating angina.

[Acute myocardial infarction secondary to anaphylactic reaction following shellfish ingestion. The need for rescue coronary angioplasty]

During anaphylactic (or anaphylactoid) reactions severe cardiovascular events may occur, acute myocardial infarction among them. This etiology of myocardial infarction, is known, although it is infrequent and only sporadically reported in literature. A case of acute myocardial infarction secondary to anaphylactic reaction following shellfish ingestion, treated with subcutaneous epinephrine and in whom a rescue coronary angioplasty was necessary is reported. The mechanism of coronary occlusion in this kind of reaction and the possible influence on the efficacy of treatment is discussed.