The preventive effect of magnesium on coronary spasm in patients with vasospastic angina

Proton pump inhibitors and cardiovascular risk: a critical review

Proton pump inhibitors (PPI) are widely used medications for gastrointestinal disorders. Recent research suggests a potential association between long-term PPI use and increased cardiovascular (CV) risk, creating a complex clinical dilemma. This review critically evaluates the current evidence for this association, considering the limitations of observational studies and the lack of definitive confirmation from randomized controlled trials.This review delves into the reported association between PPIs and adverse CV events, examining proposed mechanisms such as drug interactions, electrolyte imbalances induced by PPIs and their potential impact on cardiac and vascular function. Evidence suggests these mechanisms converge, with varying influence depending on patient populations.Clinicians require a risk-benefit analysis for each patient considering their CV risk profile. Alternative gastrointestinal therapies should be explored for high-bleeding risk patients. Medications with lower cytochrome-P450 interaction potential may be preferable among essential PPI users. Elucidating the specific mechanisms by which PPIs might influence CV health, assessing long-term vascular effects and investigating interactions with newer anticoagulant medications are crucial for future research.

Role of Magnesium, Effects of Hypomagnesemia, and Benefits of Magnesium Supplements in Cardiovascular and Chronic Kidney Diseases

Cardiovascular diseases (CVDs) account for nearly half of chronic kidney disease (CKD)-related deaths. Hypomagnesemia has been associated with various cardiovascular conditions and predicts a decline in renal function leading to end-stage renal disease (ESRD). The objective of this review is to delve into and discuss the significance of magnesium (Mg) in cardiovascular and renal functions, the clinical consequences of hypomagnesemia on CVD and CKD, and the benefits of Mg supplementation in managing CVD and CKD. This review is the result of an extensive search for pertinent articles in databases like PubMed, Medline, PubMed Central, and Google Scholar. Based on the literature search conducted in this review, we concluded that Mg protects against various CVDs and delays the progression of CKD. Mg can regulate pathways associated with inflammation, oxidative stress, and fibrosis. Therefore, maintaining slightly elevated Mg levels and timely Mg supplementation may benefit patients with CVD and CKD. There is a need for additional prospective randomized controlled trials to fully comprehend the therapeutic effects of Mg on CVD and CKD along with setting individualized target levels for serum Mg in such patients.

Therapeutic Options for Migraines in the Microsurgical Patient: A Scoping Review

BACKGROUND

There exists an increasing array of treatments proposed to prevent, alleviate, and abort symptoms of a migraine; however, for patients who undergo reconstructive microsurgery, caution must be taken to preserve vascular integrity. This study is the first-to-date scoping review of vascular and bleeding risk of current migraine therapies, with the purpose of identifying potential therapeutic agents for postoperative migraine management appropriate for microsurgical patients.

METHODS

Currently available migraine therapeutics were compiled from the UpToDate software system and the American Academy of Family Physicians. A PubMed literature review was performed for each therapeutic's effect on bleeding or vascular involvement. Data were compiled into tables of abortive, symptom-controlling and prophylactic, and nonpharmacologic treatments. Expert microsurgeons reviewed the data to provide recommendations for optimized patient care.

RESULTS

Triptans and other ergot derivatives demonstrated strong evidence of vasoconstriction and were greatly advised against for immediate postmicrosurgical use. Novel pharmaceutical therapies such as lasmiditan and calcitonin gene-related peptide antagonists have no literature indicating potential for vasoconstriction or hematoma and remain an investigational option for abortive medical treatment. For symptom control, acetaminophen appears the safest option, with clinical judgment and further research needed for use of nonsteroidal antiinflammatory drugs. Alternative treatment techniques may include migraine prophylaxis with botulinum toxin injection or nutraceutical treatment by means of magnesium supplementation or coenzyme Q10 administration, minimizing the need for additional medication in the postoperative setting.

CONCLUSIONS

Patients undergoing reconstructive microsurgery have a unique medical profile limiting the therapeutic options available to treat migraines. This review provides preliminary evidence to be considered as a guide for prescribing therapeutics for migraine in the postoperative setting.

Pharmacotherapy in patients with vasomotor disorders

Background

Anginal symptoms in patients with non-obstructive coronary artery disease are frequently related to vasomotor disorders of the coronary circulation. Although frequently overlooked, a distinct diagnosis of different vasomotor disorders can be made by intracoronary function testing. Early detection and treatment seems beneficial, but little evidence is available for the medical treatment of these disorders. Nevertheless, there are several pharmacotherapeutic options available to treat these patients and improve quality of life.

Methods & findings

We performed an extensive yet non-systematic literature search to explore available pharmacotherapeutic strategies for addressing vasomotor disorders in individuals experiencing angina and non-obstructive coronary artery disease. This article presents a comprehensive overview of therapeutic possibilities for patients exhibiting abnormal vasoconstriction (such as spasm) and abnormal vasodilation (like coronary microvascular dysfunction).

Conclusion

Treatment of vasomotor disorders can be very challenging, but a general treatment algorithm based on the existing evidence and the best available current practice is feasible.

Management of Coronary Artery Spasm

Calcium channel blockers (CCBs) are the first-line treatment for coronary artery spasm (CAS). When CAS-related angina symptoms are not well controlled by CCB therapy, long-acting nitrates or (where available) nicorandil can be added as second-line medications. In the case of CAS refractory to standard treatments, several other alternative drugs and interventions have been proposed, including the Rho-kinase inhibitor fasudil, anti-adrenergic drugs, neural therapies and percutaneous coronary interventions. In patients with syncope or cardiac arrest caused by CAS-related tachyarrhythmias, or even bradyarrhythmias, implantation of an ICD or pacemaker, respectively, should be considered according to the risk of recurrence and efficacy of vasodilator therapy.

Relationship between Inflammation and Vasospastic Angina

Coronary artery spasm (CAS) is a dynamic coronary stenosis causing vasospastic angina (VSA). However, VSA is a potentially lethal medical condition with multiple presentations, including sudden cardiac death. Despite investigations to explore its pathogenesis, no single mechanism has been found to explain the entire process of VSA occurrence. The roles of elevated local and systemic inflammation have been increasingly recognized in VSA. Treatment strategies to decrease local and systemic inflammation deserve further investigation.

Repetitive catamenial myocardial infarction due to coronary artery spasm: a case report

Background

Coronary artery spasm is an established mechanism of myocardial infarction with non-obstructive coronary arteries (MINOCA). Various mechanisms have been proposed, ranging from vascular smooth muscle hyperreactivity to endothelial dysfunction, to autonomic nervous system dysregulation.

Case summary

We report a case of a 37-year-old woman who presented with recurrent non-ST elevation myocardial infarction (NSTEMI), coinciding with her menstrual periods. Intracoronary acetylcholine provocation testing resulted in coronary spasm in the left anterior descending artery (LAD) that was relieved with nitroglycerine. Initiating calcium channel blockade and suppressing cyclical variation in sex hormones resulted in improvement of her symptoms and cessation of monthly NSTEMI events due to coronary spasm.

Discussion

Initiating calcium channel blockade and suppressing cyclical variation in sex hormones resulted in improvement of her symptoms and cessation of monthly NSTEMI events due to coronary spasm. Catamenial coronary artery spasm is a rare, but clinically important, presentation of myocardial infarction with non-obstructive coronary arteries (MINOCA).

MINOCA: One Size Fits All? Probably Not—A Review of Etiology, Investigation, and Treatment

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of conditions that include both atherosclerotic (coronary plaque disruption) and non-atherosclerotic (spontaneous coronary artery dissection, coronary artery spasm, coronary artery embolism, coronary microvascular dysfunction, and supply–demand mismatch) causes resulting in myocardial damage that is not due to obstructive coronary artery disease. Failure to identify the underlying cause may result in inadequate and inappropriate therapy in these patients. The cornerstone of managing MINOCA patients is to identify the underlying mechanism to achieve the target treatment. Intravascular imaging is able to identify different morphologic features of coronary plaques, while cardiac magnetic resonance is the gold standard for detection of myocardial infarction in the setting of MINOCA. In this review, we summarize the relevant clinical issues, contemporary diagnosis, and treatment options of MINOCA.

Pathobiology and evolving therapies of coronary artery vasospasm

Coronary artery vasospasm is a known cause of chest pain and requires a high level of clinical suspicion for diagnosis. It also remains in the differential diagnosis for patients presenting with type 2 myocardial infarction. There are few randomized controlled trials for guideline-based prevention and treatment for coronary artery vasospasm. In this article, we review updated concepts in coronary artery vasospasm. Specifically, our aim is to provide current evidence of pathophysiology, identify the risk factors, propose a diagnostic algorithm, review available evidence of evolving therapies, and identify patients who would benefit from automatic implantable cardioverter defibrillators.

Mechanically Induced Vasospasm-Evaluation of Spasmolytic Efficacy of 10 Pharmaceutical Agents Using Laser Speckle Contrast Imaging

BACKGROUND AND OBJECTIVES

Vasospasm is a thorny problem often encountered in microvascular surgery that seriously threatens the survival of vascularized tissue transfers. This investigation is dedicated to establishing a model of vasospasm and to evaluating the antispasmodic efficacy of 10 pharmacologic agents.

STUDY DESIGN/MATERIALS AND METHODS

Eighty Sprague-Dawley rats were used. After anesthesia and depilation, the femoral neurovascular bundle was exposed, and a pair of microsurgical forceps were used to trigger vasospasm of the femoral vessels by blunt dissection. Then, 10 pharmacological agents, namely, prostaglandin E1, sodium nitroprusside, magnesium sulfate, papaverine, normal saline, phentolamine, verapamil, 2% lidocaine hydrochloride, amrinone, and 12% lidocaine hydrochloride, were dripped to the femoral vessels, after which laser speckle contrast imaging was used to collect perfusion images, acquiring the perfusion and the inner caliber of the femoral vessels at multiple timepoints. Furthermore, blood perfusion and the time consumed to escape vasospasm and reach hyperperfusion in each group were calculated. The difference of spasmolytic efficacy among the agents was statistically analyzed by one-way analysis of variance.

RESULTS

There was a significant difference in antispasmodic ability among the 10 agents (P < 0.001). 10% magnesium sulfate and 12% lidocaine were distinguished among the 10 agents in resolving the vasospasm. 10% magnesium sulfate demonstrated the best antispasmodic potency, which enabled the shortest time consumed for vessels to escape spasm and reach hyperperfusion. 12% lidocaine ranked second in efficacy, demonstrating a similar effect except that it could not propel the femoral vein to a state of hyperperfusion. For the remaining agents, the time consumed for the artery to escape spasm was all significantly shortened when compared with normal saline (P < 0.001). For the venous spasm, all agents except prostaglandin E1 could significantly shorten the time consumed for the vein to escape spasm (P < 0.001).

CONCLUSIONS

In terms of resolving mechanically induced vasospasm, 10% magnesium sulfate is the best antispasmodic, followed by 12% lidocaine. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Preeclampsia: a gestational cardiorenal syndrome

It is generally accepted today that there are two different types of preeclampsia: an early-onset or placental type and a late-onset or maternal type. In the latent phase, the first one presents with a low output/high resistance circulation eventually leading in the late second or early third trimester to an intense and acutely aggravating systemic disorder with an important impact on maternal and neonatal mortality and morbidity; the other type presents initially as a high volume/low resistance circulation, gradually evolving to a state of circulatory decompensation usually in the later stages of pregnancy, with a less severe impact on maternal and neonatal outcome. For both processes, numerous dysfunctions of the heart, kidneys, arteries, veins and interconnecting systems are reported, most of them presenting earlier and more severely in early- than in late-onset preeclampsia; however, some very specific dysfunctions exist for either type. Experimental, clinical and epidemiological observations before, during and after pregnancy are consistent with gestation-induced worsening of subclinical pre-existing chronic cardiovascular dysfunction in early-onset preeclampsia, and thus sharing the pathophysiology of cardiorenal syndrome type II, and with acute volume overload decompensation of the maternal circulation in late-onset preeclampsia, thus sharing the pathophysiology of cardiorenal syndrome type 1. Cardiorenal syndrome type V is consistent with the process of preeclampsia superimposed upon clinical cardiovascular and/or renal disease, alone or as part of a systemic disorder. This review focuses on the specific differences in haemodynamic dysfunctions between the two types of preeclampsia, with special emphasis on the interorgan interactions between heart and kidneys, introducing the theoretical concept that the pathophysiological processes of preeclampsia can be regarded as the gestational manifestations of cardiorenal syndromes.

Prevention of Cardiovascular Disease: Screening for Magnesium Deficiency

Magnesium is an essential mineral naturally present in the human body, where it acts as cofactor in several enzymatic reactions. Magnesium is a key cardiovascular regulator, which maintains electrical, metabolic, and vascular homeostasis. Moreover, magnesium participates in inflammation and oxidative processes. In fact, magnesium deficiency is involved in the pathophysiology of arterial hypertension, diabetes mellitus, dyslipidemia, metabolic syndrome, endothelial dysfunction, coronary artery disease, cardiac arrhythmias, and sudden cardiac death. In consideration of the great public-health impact of cardiovascular disease, the recognition of the negative effects of magnesium deficiency suggests the possible role of hypomagnesaemia as cardiovascular risk factor and the use of serum magnesium level for the screening and prevention of cardiovascular risk factors and cardiovascular diseases. Moreover, it might help with the identification of new therapeutical strategies for the management of cardiovascular disease through magnesium supplementation.

Maternal Venous Hemodynamic Dysfunction in Proteinuric Gestational Hypertension: Evidence and Implications

This review summarizes current knowledge from experimental and clinical studies on renal function and venous hemodynamics in normal pregnancy, in gestational hypertension (GH) and in two types of preeclampsia: placental or early-onset preeclampsia (EPE) and maternal or late-onset (LPE) preeclampsia, presenting at <34 weeks and ≥34 weeks respectively. In addition, data from maternal venous Doppler studies are summarized, showing evidence for (1) the maternal circulation functioning closer to the upper limits of capacitance than in non-pregnant conditions, with intrinsic risks for volume overload, (2) abnormal venous Doppler measurements obtainable in preeclampsia, more pronounced in EPE than LPE, however not observed in GH, and (3) abnormal venous hemodynamic function installing gradually from first to third trimester within unique pathways of general circulatory deterioration in GH, EPE and LPE. These associations have important clinical implications in terms of screening, diagnosis, prevention and management of gestational hypertensive diseases. They invite for further hypothesis-driven research on the role of retrograde venous congestion in the etiology of preeclampsia-related organ dysfunctions and their absence in GH, and also challenge the generally accepted view of abnormal placentation as the primary cause of preeclampsia. The striking similarity between abnormal maternal venous Doppler flow patterns and those observed at the ductus venosus and other abdominal veins of the intra-uterine growth restricted fetus, also invites to explore the role of venous congestion in the intra-uterine programming of some adult diseases.

Myocardial infarction with non-obstructive coronary arteries: a focus on vasospastic angina

Vasospastic angina (VSA) is considered a broad diagnostic category including documented spontaneous episodes of angina pectoris produced by coronary epicardial vasospasm as well as those induced during provocative coronary vasospasm testing and coronary microvascular dysfunction due to microvascular spasm. The hallmark feature of VSA is rest angina, which promptly responds to short-acting nitrates; however, VSA can present with a great variety of symptoms, ranging from stable angina to acute coronary syndrome and even ventricular arrhythmia. VSA is more prevalent in females, who can present with symptoms different from those among male patients. This may lead to an underestimation of cardiac causes of chest-related symptoms in female patients, in particular if the coronary angiogram (CAG) is normal. Evaluation for the diagnosis of VSA includes standard 12-lead ECG during the attack, Holter monitoring, exercise testing, and echocardiography. Patients suspected of having VSA with a normal CAG without a clear myocardial or non-cardiac cause are candidates for provocative coronary vasospasm testing. The gold standard method for provocative coronary vasospasm testing involves the administration of a provocative drug during CAG while monitoring patient symptoms, ECG and documentation of the coronary artery. Treatment of VSA consists of lifestyle adaptations and pharmacotherapy with calcium channel blockers and nitrates.

Coronary spasm: It’s common, but it’s still unsolved

Coronary spasm is caused by a transient coronary narrowing due to the constriction of epicardial coronary artery, which leads to myocardial ischemia. More than 50 years have passed since the first recognition of coronary spasm, and many findings on coronary spasm have been reported. Coronary spasm has been considered as having pivotal roles in the cause of not only rest angina but also exertional angina, acute coronary syndrome, and heart failure. In addition, several new findings of the mechanism of coronary spasm have emerged recently. The diagnosis based mainly on coronary angiography and spasm provocation test and the mainstream treatment with a focus on a calcium-channel blocker have been established. At a glance, coronary spasm or vasospastic angina (VSA) has become a common disease. On the contrary, there are several uncertain or unsolved problems regarding coronary spasm, including the presence of medically refractory coronary spasm (intractable VSA), or an appropriate use of implantable cardioverter defibrillator in patients with cardiac arrest who have been confirmed as having coronary spasm. This editorial focused on coronary spasm, including recent topics and unsolved problems.

Coronary artery spasm: Current knowledge and residual uncertainties

Myocardial ischaemia results from a direct mismatch between oxygen supply and demand, commonly arising as a result of coronary atherosclerosis, microvascular dysfunction or acute thrombosis and luminal obstruction. However, transient ischaemia may also occur due to coronary spasm leading to acute and unexpected myocardial ischaemia without obvious visible coronary pathology. Aside from symptoms of chest pain, coronary spasm can cause infarction, LV impairment, promote life threatening arrhythmias and ultimately sudden cardiac death. While therapeutic options are available, controversies exist around diagnosis, pathology, management and prognosis. This review summarises some of the common questions in this area. In particular we explore and discuss the available evidence for the pharmacological treatment of coronary spasm, and strategies for identification and management of very high risk patients to try and reduce the incidence of sudden premature death.

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Myocardial ischaemia results from a mismatch between oxygen supply and demand.

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Spasm might lead to myocardial ischaemia without visible coronary pathology.

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Coronary spasm can cause infarction, LV impairment and sudden cardiac death.

Post-valvular surgery multi-vessel coronary artery spasm - A literature review

Coronary artery spasm (CAS) refers to the spontaneous or stimuli-induced transient, often localized and intense subtotal or total constriction/occlusion of the epicardial coronary artery, usually concomitant with angina pectoris with associated elevation of the ST segment on electrocardiogram (ECG). In this article, we present a literature review on post-valvular surgery CAS and report the clinical case of a 77 year-old man who experienced severe early post-aortic surgery chest pain and hemodynamic instability. Emergent coronary angiography revealed severe occlusion of multiple branches of both coronary arteries. The CAS was alleviated with intracoronary infusion of nitroglycerin.

Coronary spasm that caused non-ST elevation myocardial infarction appeared in cath lab due to vasovagal reaction

Coronary artery spasm is sometimes an unrecognized cause of myocardial ischemia. Myocardial ischemia is not always a product of fixed stenosis; it can also be induced by dynamic, transient stenosis. The angiogram represents the current state of vasculature at the time of examination and absence of stenosis does not mean disease absence. We present a case of right coronary artery spasm that caused non-ST elevation myocardial infarction and arrhythmias and was induced again in the cath lab due to vasovagal reaction.

Mg supplementation protects against ritonavir-mediated endothelial oxidative stress and hepatic eNOS downregulation

Ritonavir (RTV), a prototypical protease inhibitor currently used as a key component of anti-HIV therapy, is known for its endothelial and hepatic toxicity. The effects of RTV and magnesium supplementation on cultured bovine endothelial cell (EC) and rat hepatic endothelial nitric oxide synthase (eNOS) status were investigated. RTV dose-dependently (5-30 µM) decreased EC viability after 48 h; high Mg (2mM) significantly attenuated the lost viability. ECs incubated with 15 µM RTV for 6 to 24h resulted in two- to fourfold elevation of oxidized glutathione and a 25% loss of total glutathione. At 24h, EC superoxide production due to RTV was detected by dihydroethidium staining and increased 41% when quantified by flow cytometry; altered glutathione status and superoxide levels were both substantially reversed by 2mM Mg. RTV reduced eNOS mRNA (-25% at 24 h) and led to decreased eNOS dimer/monomer ratios; nitric oxide-derived products decreased 40%; both changes were attenuated by Mg supplementation. In male Lewis-Brown Norway rats, RTV administration (75 mg/kg/day, 5 weeks) resulted in an 85% increase in plasma 8-isoprostane and a 23% decrease in hepatic eNOS mRNA; concomitantly, eNOS protein decreased 75%, whereas plasma nitrite level was reduced 48%. Dietary Mg supplementation (sixfold higher than control) prevented the eNOS mRNA decrease along with lowering 8-isoprostane and restored the eNOS protein and plasma nitrite levels comparable to controls. In conclusion, Mg attenuates RTV-mediated EC oxidative eNOS dysfunction and downregulation of hepatic eNOS expression; we suggest that Mg can serve as a beneficial adjunct therapeutic against RTV-mediated eNOS toxicity.

Coronary artery spasm: review and update

Coronary artery spasm (CAS), an intense vasoconstriction of coronary arteries that causes total or subtotal vessel occlusion, plays an important role in myocardial ischemic syndromes including stable and unstable angina, acute myocardial infarction, and sudden cardiac death. Coronary angiography and provocative testing usually is required to establish a definitive diagnosis. While the mechanisms underlying the development of CAS are still poorly understood, CAS appears to be a multifactorial disease but is not associated with the traditional risk factors for coronary artery disease. The diagnosis of CAS has important therapeutic implications, as calcium antagonists, not β-blockers, are the cornerstone of medical treatment. The prognosis is generally considered benign; however, recurrent episodes of angina are frequently observed. We provide a review of the literature and summarize the current state of knowledge regarding the pathogenesis of CAS.

Managing the Complications of Mild Therapeutic Hypothermia in the Cardiac Arrest Patient

Mild therapeutic hypothermia (MTH) is used to lower the core body temperature of cardiac arrest (CA) patients to 32°C from 34°C to provide improved survival and neurologic outcomes after resuscitation from in-hospital or out-of-hospital CA. Despite the improved benefits of MTH, there are potentially unforeseen complications associated during management. Although the adverse effects are transient, the clinician should be aware of the associated complications when managing the patient receiving MTH. We aim to provide the medical community comprehensive information related to the potential complications of survivors of CA receiving MTH, as it is imperative for the clinician to understand the physiologic changes that take place in the patient receiving MTH and how to prepare for them and manage them if they do occur. We hope to provide information of how to manage these potential complications through both a review of the current literature and a reflection of our own experience.

Higher serum uric acid and lipoprotein(a) are correlated with coronary spasm

It has been reported that a major cause of coronary vasospastic angina (VSA) is endothelial dysfunction of the coronary artery. On the other hand, some studies showed that serum uric acid and lipoprotein(a) are correlated with endothelial dysfunction. Thus, we examined whether uric acid and lipoprotein(a), are correlated with VSA. Four hundred forty-one patients with suspected VSA who underwent a coronary angiogram with acetylcholine provocation (ACh test) during an 8-year period were enrolled. We divided them into a VSA group, who showed coronary spasm by the ACh test, and an atypical chest pain (ACP) group, who showed negative ACh test. We compared serum markers between the two groups, including low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, high-sensitivity C-reactive protein (hs-CRP), lipoprotein(a), fibrinogen, total plasminogen activator inhibitor-1, and uric acid. Uric acid, hs-CRP, and lipoprotein(a) were significantly higher in the VSA group than in the ACP group (all P < 0.05) while there were no significant differences in the other parameters. Multivariate analyses identified uric acid and lipoprotein(a) as significant independent markers for VSA. Uric acid and lipoprotein(a) are correlated with VSA, and medical intervention to decrease uric acid and lipoprotein(a) might be effective in controlling VSA.

A patient with repeated catastrophic multi-vessel coronary spasm after zotarolimus-eluting stent implantation

Drug-eluting stents (DES) have gained great popularity because of extraordinarily low rates of restenosis. Despite these superior clinical outcomes, several cases regarding the severe multi-vessel coronary spasm, although rare, after the placement of first generation DES have been reported. We report a case of severe, multi-vessel coronary spasm that occurred two occasions after placement of a zotarolimus-eluting stent, one of the second generation DES, in a 42-year-old man with unstable angina. The first incidence was relieved by intracoronary nitroglycerin alone, and second incident, which had combined fixed stenosis was treated with intracoronary nitroglycerin and everolimus-eluting stent.

Magnesium and diltiazem relaxes phenylephrine-precontracted rat aortic rings

Perioperative vasospasm during cardiovascular surgery is a challenging problem. Several vasodilator agents are frequently utilized for its prevention in surgical practice. Magnesium and diltiazem both have known potential vasorelaxant effects. We planned to compare the efficacy of diltiazem and magnesium in relieving phenylephrine-precontracted rat aortic rings. Ten young adult female Wistar albino rats weighing 230-260 g were used in this study. The aortic rings in the organ bath equilibrated and reached their baseline tension. Precontraction was induced by 0.001 mmol/l phenylephrine and cumulative concentration-relaxation curves were obtained by consecutively increasing the addition of either diltiazem (10(-6)-0.1 mmol/l) or magnesium (0.1-10 mmol/l). The mean maximal relaxation responses observed by diltiazem and magnesium on separate aortic rings were 90 ± 3 and 53 ± 2%, respectively. The calculated EC50 of diltiazem was 0.01035 mmol/l, whereas the EC50 of magnesium was 4.064 mmol/l (P < 0.05). Both magnesium and diltiazem produced vasorelaxation on phenylephrine-precontracted rat aortic rings in this study, but the potency of diltiazem regarding the EC50 value was significantly higher than that of magnesium. Magnesium could be a candidate together with diltiazem to inhibit vasospasm on arterial grafts during coronary bypass surgery.

Variant angina and coronary artery spasm: the clinical spectrum, pathophysiology, and management

Variant angina is a form of angina pectoris that shows transient ST-segment elevation on electrocardiogram during an attack of chest pain. Ischemic episodes of variant angina show circadian variation and often occur at rest from midnight to early morning. Ischemic episodes also occur during mild exercise in the early morning. However, they are not usually induced by strenuous exercise in the afternoon. Other important clinical features of variant angina include the high frequency of asymptomatic ischemic episodes and the syncope that sometimes occur during the ischemic episodes. Syncope is due to severe arrhythmias, including ventricular tachycardia, ventricular fibrillation, and high-degree atrioventricular block. Coronary artery spasm is the mechanism of ischemic episodes in variant angina. The incidence of coronary artery spasm shows a racial difference and is higher in Japanese than in Caucasians. Coronary arteriograms are normal or near-normal in most Japanese patients with variant angina. Deficient basal release of nitric oxide (NO) due to endothelial dysfunction, and enhanced vascular smooth muscle contractility with the involvement of the Rho/Rho-kinase pathway are reported to play important roles in the pathogenesis of coronary artery spasm. Other precipitating factors of coronary artery spasm include imbalance in autonomic nervous activity, increased oxidative stress, chronic low-grade inflammation, magnesium deficiency, and genetic susceptibility. The genetic risk factors associated with coronary artery spasm include gene polymorphisms of endothelial NO synthase (NOS), paraoxonase, and other genes. Calcium channel blockers are extremely effective in preventing coronary spasm. The long-acting nitrate, nicorandil, and Rho-kinase inhibitor are also useful for inhibiting coronary artery spasm. Because variant angina can lead to acute myocardial infarction, fatal arrhythmias, and sudden death, early treatment is important. The prognosis of patients with variant angina is favorable, if early complications can be overcome. However, because coronary artery spasm cannot be suppressed in some patients, even with multiple medications, medications to suppress intractable coronary artery spasm must be developed.

Disruption of coronary vasomotor function: the coronary spasm syndrome

Abnormal coronary vasoconstriction, or coronary spasm, can be the result of several factors, including local and neuroendocrine aberrations. It can manifest clinically as a coronary syndrome and plays an important role in the genesis of myocardial ischemia. Over the past half century, coronary angiography allowed the in vivo demonstration of spasm in patients who fit the initial clinical description of the condition as reported by Prinzmetal et al. Several clinical, basic, and more recently, genetic studies have provided insight into the pathogenesis, manifestations, and therapy of this condition. It is not uncommonly encountered in patients with coronary syndromes and absence of clearly pathologic lesions on angiography. Provocation tests utilizing pharmacologic and nonpharmacologic stimuli combined with imaging (echocardiography or coronary angiography) can help make the correct diagnosis. The use of calcium channel blockers and long-acting nitrates is currently considered standard of care and the overall prognosis appears to be good. The recent discovery of genetic abnormalities predisposing to abnormal spasm of the coronaries has stimulated interest in the development of targeted therapies for the management of this condition.

Induced hypothermia for trauma: current research and practice

Induction of hypothermia with the goal of providing therapeutic benefit has been accepted for use in the clinical setting of adult cardiac arrest and neonatal hypoxic-ischemic encephalopathy (HIE). However, its potential as a treatment in trauma is not as well defined. This review discusses potential benefits and complications of induced hypothermia (IH) with emphasis on the current state of knowledge and practice in various types of trauma. There is excellent preclinical research showing that in cases of penetrating trauma with cardiac arrest, inducing hypothermia to 10 degrees C using cardiopulmonary bypass (CPB) could possibly save those otherwise likely to die without causing neurologic sequelae. A human trial of this intervention is about to get underway. Preclinical studies suggest that inducing hypothermia may be useful to delay cardiac arrest in penetrating trauma victims who are hypotensive. There is potential for IH to be used in cases of blunt trauma, but it has not been well studied. In the case of traumatic brain injury (TBI), clinical trials have shown conflicting results, despite almost uniform efficacy seen in preclinical experiments. Major studies are analyzed and ways to standardize its use and optimize future clinical trials are discussed. More preclinical and clinical research is needed to better define whether there could be a role for IH in the case of spinal cord injuries.

Current advances in the understanding of coronary vasospasm

Recent years have witnessed progress in our understanding of coronary vasospasm (CVS). It is evident that this is not only an East Asian but also a global disease associated with significant symptoms and possible lethal sequelae for afflicted individuals. A correct diagnosis depends on the understanding of pathogenesis and symptomatology of CVS. With the correct diagnosis, we can manage CVS patients effectively and promptly, providing optimal patient safety. Advances in our understanding of interactions between inflammation, endothelium, and smooth muscle cells have led to substantial progress in understanding the pathogenesis of symptoms in CVS and have provided some insights into the basic etiology of this disorder in some patient subpopulations. We look forward to a time when therapy will address pathophysiology and perhaps, even the primary etiology.

Coronary vasospasm produces reversible perfusion defects observed during adenosine triphosphate stress myocardial single-photon emission computed tomography

BACKGROUND

Adenosine triphosphate stress thallium-201 single-photon emission computed tomography (ATP-SPECT) is useful for diagnosing coronary artery disease (CAD), although sometimes false positive results are observed. It has not been established whether a coronary spasm is responsible for the false positive findings during ATP-SPECT.

HYPOTHESIS

We investigated whether coronary spasm is one of the factors which produces reversible defects on ATP-SPECT.

METHODS

Eighty-six patients (mean age: 62 y; 58 men) who underwent both spasm-provocation testing by coronary angiography and ATP-SPECT, were selected for the study. Patients with coronary narrowing (>30%), myocardial infarction, or heart failure were excluded. Patients were divided into 2 groups based on whether the spasm-provocation test result was positive (vasospastic angina [VSA] group, n = 46) or negative (non-VSA group, n = 39).

RESULTS

The body mass index was lower in the VSA group than in the non-VSA group (p = 0.005). On ATP-SPECT imaging, any type of reversible defect was observed more frequently in the VSA group (68%) than in the non-VSA group (36%, p = 0.0027). Logistic regression analysis demonstrated that the presence of reversible defects was one of the factors accounting for the presence of coronary vasospasm (p = 0.0022, R2 = 0.172).

CONCLUSIONS

The findings suggest that reversible defects on ATP-SPECT imaging are frequently present in patients with coronary vasospasm. Coronary spasm may be considered as 1 of the factors, which produce reversible defects on ATP-SPECT, observed in patients with chest symptoms and angiographically normal coronary arteries.

Electrolyte disturbances in the intensive care unit

The development of many electrolyte disturbances in the ICU can be prevented by attention to the use of intravenous fluids and nutrition. Hyponatremia is a relative contraindication to the use of hypotonic intravenous fluids and hypernatremia calls for the administration of water. Formulae have been devised to guide the therapy of severe hyponatremia and hypernatremia. All formulae regard the patient as a closed system, and none takes into account ongoing fluid losses that are highly variable between patients. Thus, therapy of severe hyponatremia and hypernatremia must be closely monitored with serial electrolyte measurements. The significance of hypocalcemia in the critically ill is controversial. Hypokalemia, hypophosphatemia, and hypomagnesemia should be corrected.

Transient electrocardiographic recording of acute myocardial ischemia with ST-segment elevation of the diaphragmal location accompanied by a total atrioventricular block as an initial manifestation of Prinzmetal’s angina — A case report

Prinzmetal’s angina, also known as Prinzmetal’s variant or Prinzmetal’s vasospastic angina is characterized by angina attacks caused by spasm of the great epicardial coronary arteries. Coronary artery endothelial dysfunction plays a crucial role in the development of this vasospastic angina. The attacks of vasospastic angina can be prevented with calcium antagonists and nitrates, whereas in refractory variant angina, coronary angioplasty with stenting may help prevent further coronary spasm. In this case report, we present a 52-year-old male patient with a transient electrocardiographic recording of acute myocardial ischemia with ST-segment elevation of the diaphragmal location accompanied by a total atrioventricular block immediately after exercise testing and as a first manifestation of Prinzmetal’s angina. After regression of the symptoms and electrocardiographic changes, significant pathomorphologic changes of coronary arteries were excluded by coronary angiography. Following discharge, the patient was treated with calcium antagonists and did not show symptoms during a 4-year follow-up period.

Myocardial bridging increases the risk of coronary spasm

BACKGROUND

Myocardial bridging (MB) has been associated with cardiac events. Whether coronary spasm is one factor contributing to those events is unknown.

HYPOTHESIS

This study investigated whether the likelihood of coronary spasm is increased in patients with MB.

METHODS

A spasm-provocation test was performed by infusing acetylcholine into the left coronary artery in 114 Japanese patients with chest pain. The test result was defined as positive when the diameter of the coronary artery was reduced by > or = 50% and ST-segment changes were documented. Myocardial bridging was defined as a > 15% reduction in coronary arterial diameter during systole after intracoronary injection of nitroglycerin.

RESULTS

Myocardial bridging was identified in 41 patients (36%) and was located in the mid-segment of the left anterior descending coronary artery (LAD) in all patients. Patients with MB experienced coronary spasm more frequently than patients without MB (MB+: 73%; MB-: 40%, p = 0.0006). Furthermore, among patients with a positive spasm-provocation test, coronary spasm occurred more frequently in the mid-segment of the LAD in patients with MB than in those without MB (MB+: 73%; MB-: 45%, p = 0.0259). Multivariate regression analysis demonstrated that MB was a predictor of coronary spasm (odds ratio: 3.478, p = 0.0088).

CONCLUSIONS

These results suggest that MB increases the risk of coronary spasm and that coronary spasm may be the proximate etiology of cardiac events associated with MB.

[Controlled mild-to-moderate hypothermia in the intensive care unit]

Controlled hypothermia is used as a therapeutic intervention to provide neuroprotection and (more recently) cardioprotection. The growing insight into the underlying pathophysiology of apoptosis and destructive processes at the cellular level, and the mechanisms underlying the protective effects of hypothermia, have led to improved application and to a widening of the range of potential indications. In many centres hypothermia has now become part of the standard therapy for post-anoxic coma in certain patients, but for other indications its use still remains controversial. The negative findings of some studies may be partly explained by inadequate protocols for the application of hypothermia and insufficient attention to the prevention of potential side effects. This review deals with some of the concepts underlying hypothermia-associated neuroprotection and cardioprotection, and discusses some potential clinical indications as well as reasons why some clinical trials may have produced conflicting results. Practical aspects such as methods to induce hypothermia, as well as the side effects of cooling are also discussed.

Magnesium intake and risk of coronary heart disease among men

OBJECTIVE

Our aim in this study was to assess the relationship between magnesium intake and risk of coronary heart disease (CHD) among men.

METHODS

A total of 39,633 men in the Health Professionals Follow-up Study who returned a dietary questionnaire in 1986 were followed up for 12 years. Intakes of magnesium, zinc and potassium and other nutrients were assessed in 1986, 1990 and 1994. Total CHD incidence (nonfatal myocardial infarction (MI) and fatal CHD) was ascertained by biennial questionnaire and mortality surveillance confirmed by medical record review. Standard CHD risk factors were recorded biennially.

RESULTS

During 12 years of follow-up (414,285 person-years), we documented 1,449 cases of total CHD (1,021 non-fatal MI cases, and 428 fatal CHD). The age-adjusted relative risk (RR) of developing CHD in the highest quintile (median intake = 457 mg/day) compared with the lowest quintile (median intake = 269 mg/day) was 0.73 (95% CI 0.62-0.87, p for trend <0.0001). After controlling for standard CHD risk factors and dietary factors, the RR for developing CHD among men in the highest total magnesium intake quintile compared with those in the lowest was 0.82 (95% CI 0.65-1.05, p for trend = 0.08). For supplemental magnesium intake, the RR comparing the highest quintile to non-supplement users was 0.77 (95% CI 0.56-1.06, p for trend = 0.14).

CONCLUSIONS

These results suggest that intake of magnesium may have a modest inverse association with risk of CHD among men.

Application of therapeutic hypothermia in the intensive care unit. Opportunities and pitfalls of a promising treatment modality--Part 2: Practical aspects and side effects

Induced hypothermia can be used to protect the brain from post-ischemic and traumatic neurological injury. Potential clinical applications and the available evidence are discussed in a separate paper. This review focuses on the practical aspects of cooling and physiological changes induced by hypothermia, as well as the potential side effects that may develop. These side effects can be serious and, if not properly dealt with, may negate some or all of hypothermia's potential benefits. However, many of these side effects can be prevented or modified by high-quality intensive care treatment, which should include careful monitoring of fluid balance, tight control of metabolic aspects such as glucose and electrolyte levels, prevention of infectious complications and various other interventions. The speed and duration of cooling and rate of re-warming are key factors in determining whether hypothermia will be effective; however, the risk of side effects also increases with longer duration. Realizing hypothermia's full therapeutic potential will therefore require meticulous attention to the prevention and/or early treatment of side effects, as well as a basic knowledge and understanding of the underlying physiological and pathophysiological mechanisms. These and other, related issues are dealt with in this review.

Coronary vasospasm and the regulation of coronary blood flow

Under physiologic conditions, epicardial arteries contribute minimally to coronary vascular resistance. However, in the presence of endothelial dysfunction, stimuli that normally produce vasodilation may instead cause constriction. Examples include neural release of acetylcholine or norepinephrine, platelet activation and production of serotonin and thrombin, and release of local factors such as bradykinin. This shift from a primary endothelial-mediated vasodilator influence to one of endothelial dysfunction and unchecked vasoconstriction is precisely the milieu in which coronary vasospasm is observed. This condition, which typically occurs during periods of relatively sedentary activity, is associated with focal and transient obstruction of an epicardial arterial segment resulting in characteristic echocardiographic changes and symptoms of myocardial ischemia. This review highlights the current understanding of mechanisms regulating the coronary circulation during health and examines the pathophysiologic changes that occur with coronary spasm. Genetic and other predisposing conditions are addressed, as well as novel therapies based on recent mechanistic insights of the coronary contractile dysfunction associated with coronary spasm.

The therapeutic use of magnesium in anesthesiology, intensive care and emergency medicine: a review

PURPOSE

To review current knowledge concerning the use of magnesium in anesthesiology, intensive care and emergency medicine.

METHODS

References were obtained from Medline(R) (1995 to 2002). All categories of articles (clinical trials, reviews, or meta-analyses) on this topic were selected. The key words used were magnesium, anesthesia, analgesia, emergency medicine, intensive care, surgery, physiology, pharmacology, eclampsia, pheochromocytoma, asthma, and acute myocardial infarction.

PRINCIPLE FINDINGS

Hypomagnesemia is frequent postoperatively and in the intensive care and needs to be detected and corrected to prevent increased morbidity and mortality. Magnesium reduces catecholamine release and thus allows better control of adrenergic response during intubation or pheochromocytoma surgery. It also decreases the frequency of postoperative rhythm disorders in cardiac surgery as well as convulsive seizures in preeclampsia and their recurrence in eclampsia. The use of adjuvant magnesium during perioperative analgesia may be beneficial for its antagonist effects on N-methyl-D-aspartate receptors. The precise role of magnesium in the treatment of asthmatic attacks and myocardial infarction in emergency conditions needs to be determined.

CONCLUSIONS

Magnesium has many known indications in anesthesiology and intensive care, and others have been suggested by recent publications. Because of its interactions with drugs used in anesthesia, anesthesiologists and intensive care specialists need to have a clear understanding of the role of this important cation.

Tetrahydrobiopterin improves coronary endothelial function, but does not prevent coronary spasm in patients with vasospastic angina

Reduced bioavailability of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, and the resulting decrease in NO in the coronary circulation may be involved in the pathogenesis of coronary spasm. The present study investigated the effects of BH4 on the vascular response to acetylcholine (ACh) in 28 patients with vasospastic angina (VA) using quantitative angiography. After recording the vascular responses to ACh (3 and 30 microg/min), either BH4 (1 mg/min) or saline was infused into the coronary artery for 2 min before and during a subsequent infusion of ACh. With the 3 microg/min dose of ACh, BH4 attenuated the ACh-induced decrease in coronary diameter in both the nonspastic segments (-1.1 +/- 2.2% ACh vs 6.0 +/- 2.8% ACh+BH4) and spastic segments (-6.3 +/- 2.7% ACh vs 2.9 +/- 2.7% ACh+BH4), but did not influence the ACh-induced coronary spasm at 30 microg/min (-57.3 +/-2.4% ACh vs -55.3 +/- 2.4% ACh+BH4). In the control patients, saline did not influence either the spastic or nonspastic vasoconstrictor responses to ACh. Acute administration of BH4 improves coronary endothelial function, but does not prevent coronary spasm in patients with VA.