Managing critically ill patients with esmolol. An ultra short-acting beta-adrenergic blocker

Pathophysiology and Acute Management of Tachyarrhythmias in Pheochromocytoma: JACC Review Topic of the Week

Pheochromocytomas, arising from chromaffin cells, produce catecholamines, epinephrine and norepinephrine. The tumor biochemical phenotype is defined by which of these exerts the greatest influence on the cardiovascular system when released into circulation in high amounts. Action on the heart and vasculature can cause potentially lethal arrhythmias, often in the setting of comorbid blood pressure derangements. In a review of electrocardiograms obtained on pheochromocytoma patients (n = 650) treated at our institution over the last decade, severe and refractory sinus tachycardia, atrial fibrillation, and ventricular tachycardia were found to be the most common or life-threatening catecholamine-induced tachyarrhythmias. These arrhythmias, arising from catecholamine excess rather than from a primary electrophysiologic substrate, require special considerations for treatment and complication avoidance. Understanding the synthesis and release of catecholamines, the adrenoceptors catecholamines bind to, and the cardiac and vascular response to epinephrine and norepinephrine underlies optimal management in catecholamine-induced tachyarrhythmias.

Postoperative Management in Patients with Pheochromocytoma and Paraganglioma

Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-secreting neuroendocrine tumors of the adrenal medulla and sympathetic/parasympathetic ganglion cells, respectively. Excessive release of catecholamines leads to episodic symptoms and signs of PPGL, which include hypertension, headache, palpitations, and diaphoresis. Intraoperatively, large amounts of catecholamines are released into the bloodstream through handling and manipulation of the tumor(s). In contrast, there could also be an abrupt decline in catecholamine levels after tumor resection. Because of such binary manifestations of PPGL, patients may develop perplexing and substantially devastating cardiovascular complications during the perioperative period. These complications include hypertension, hypotension, arrhythmias, myocardial infarction, heart failure, and cerebrovascular accident. Other complications seen in the postoperative period include fever, hypoglycemia, cortisol deficiency, urinary retention, etc. In the interest of safe patient care, such emergencies require precise diagnosis and treatment. Surgeons, anesthesiologists, and intensivists must be aware of the clinical manifestations and complications associated with a sudden increase or decrease in catecholamine levels and should work closely together to be able to provide appropriate management to minimize morbidity and mortality associated with PPGLs.

Control of hypertension in the critically ill: a pathophysiological approach

Severe acute arterial hypertension can be associated with significant morbidity and mortality. After excluding a reversible etiology, choice of therapeutic intervention should be based on evaluation of a number of factors, such as age, comorbidities, and other ongoing therapies. A rational pathophysiological approach should then be applied that integrates the effects of the drug on blood volume, vascular tone, and other determinants of cardiac output. Vasodilators, calcium channel blockers, and beta-blocking agents can all decrease arterial pressure but by totally different modes of action, which may be appropriate or contraindicated in individual patients. There is no preferred agent for all situations, although some drugs may have a more attractive profile than others, with rapid onset action, short half-life, and fewer adverse reactions. In this review, we focus on the main mechanisms underlying severe hypertension in the critically ill and how using a pathophysiological approach can help the intensivist decide on treatment options.

Pharmacological management of hypertensive emergencies and urgencies: focus on newer agents

INTRODUCTION

Hypertensive crises are categorized as hypertensive emergencies and urgencies depending on the presence of acute target-organ damage; the former are potentially life-threatening medical conditions, requiring urgent treatment under close monitoring. Although several short-acting intravenous antihypertensive agents are approved for this purpose, until recently little evidence from proper trials on the relative merits of different therapies was available.

AREAS COVERED

This article discusses in brief the pathophysiology, epidemiology and diagnostic approach of hypertensive crises and provides an extensive overview of established and emerging pharmacological agents for the treatment of patients with hypertensive emergencies and urgencies.

EXPERT OPINION

Agents such as sodium nitroprusside, nitroglycerin and hydralazine have been used for many years as first-line options for patients with hypertensive emergencies, although their potential adverse effects and difficulties in use were well known. With time, equally potent and less toxic alternatives, including nicardipine, fenoldopam, labetalol and esmolol are increasingly used worldwide. Recently, clevidipine, a third-generation dihydropyridine calcium-channel blocker with unique pharmacodynamic and pharmacokinetic properties was added to our therapeutic armamentarium and was shown in clinical trials to reduce mortality when compared with nitroprusside. In view of such evidence, a change in pharmacological treatment practices for hypertensive crises toward newer and safer agents is warranted.

Hypertensive emergencies: an update

PURPOSE OF REVIEW

Systemic hypertension (HTN) is a common medical condition affecting over 1 billion people worldwide. One to two percent of patients with HTN develop acute elevations of blood pressure (hypertensive crises) that require medical treatment. However, only patients with true hypertensive emergencies require the immediate and controlled reduction of blood pressure with an intravenous antihypertensive agent.

RECENT FINDINGS

Although the mortality from hypertensive emergencies has decreased, the prevalence and demographics of this disorder have not changed over the last 4 decades. Clinical experience and reported data suggest that patients with hypertensive urgencies are frequently inappropriately treated with intravenous antihypertensive agents, whereas patients with true hypertensive emergencies are overtreated with significant complications.

SUMMARY

Despite published guidelines, most patients with hypertensive crises are poorly managed with potentially severe outcomes.

Pheochromocytoma - update on disease management

Pheochromocytomas are rare endocrine tumors that can present insidiously and remain undiagnosed until death or onset of clear manifestations of catecholamine excess. They are often referred to as one of the 'great mimics' in medicine. These tumors can no longer be regarded as a uniform disease entity, but rather as a highly heterogeneous group of chromaffin cell neoplasms with different ages of onset, secretory profiles, locations, and potential for malignancy according to underlying genetic mutations. These aspects all have to be considered when the tumor is encountered, thereby enabling optimal management for the patient. Referral to a center of specialized expertise for the disease should be considered wherever possible. This is not only important for surgical management of patients, but also for post-surgical follow up and screening of disease in patients with a hereditary predisposition to the tumor. While preoperative management has changed little over the last 20 years, surgical procedures have evolved so that laparoscopic resection is the standard of care and partial adrenalectomy should be considered in all patients with a hereditary condition. Follow-up testing is essential and should be recommended and ensured on a yearly basis. Managing such patients must now also take into account possible underlying mutations and the appropriate selection of genes for testing according to disease presentation. Patients and family members with identified mutations then require an individualized approach to management. This includes consideration of distinct patterns of biochemical test results during screening and the appropriate choice of imaging studies for tumor localization according to the mutation and associated differences in predisposition to adrenal, extra-adrenal and metastatic disease.

Point of controversy: perioperative care of patients undergoing pheochromocytoma removal-time for a reappraisal?

Adrenalectomy for pheochromocytoma is reported with a mortality close to zero in recent studies. The dogma of preoperative fluid and hypotensive drug administrations is widely applied in patients scheduled for pheochromocytoma removal and is assumed to have a beneficial effect on operative outcomes. This paradigm is only based on historical studies of non-standardized practices and criteria for efficacy, with no control group. Pre- and intraoperative hypovolemia have never been demonstrated in patients scheduled for pheochromocytoma removal. Recent improvements in outcome of patients undergoing adrenalectomy for pheochromocytoma could also be the result of improvement in surgical techniques and refinement in anesthetic practices. Whether better knowledge of the disease, efficiency of available intravenous short-acting vasoactive drugs, and careful intraoperative handling of the tumor make it possible to omit preoperative preparation in most patients scheduled for pheochromocytoma removal is presently questionable. We reviewed available literature in this respect.

Blood pressure control in acute cerebrovascular disease

Acute cerebrovascular diseases (ischemic stroke, intracerebral hemorrhage, and subarachnoid hemorrhage) affect 780,000 Americans each year. Physicians who care for patients with these conditions must be able to recognize when acute hypertension requires treatment and should understand the principles of cerebral autoregulation and perfusion. Physicians should also be familiar with the various pharmacologic agents used in the treatment of cerebrovascular emergencies. Acute ischemic stroke frequently presents with hypertension, but the systemic blood pressure should not be treated unless the systolic pressure exceeds 220 mm Hg or the diastolic pressure exceeds 120 mm Hg. Overly aggressive treatment of hypertension can compromise collateral perfusion of the ischemic penumbra. Hypertension associated with intracerebral hemorrhage can be treated more aggressively to minimize hematoma expansion during the first 3 to 6 hours of illness. Subarachnoid hemorrhage is usually due to aneurysmal rupture; systolic blood pressure should be kept <150 mm Hg to prevent re-rupture of the aneurysm. Nicardipine and labetalol are recommended for rapidly treating hypertension during cerebrovascular emergencies. Sodium nitroprusside is not recommended due to its adverse effects on cerebral autoregulation and intracranial pressure. Hypoperfusion of the injured brain should be avoided at all costs.

Acute pulmonary edema due to stress cardiomyopathy in a patient with aortic stenosis: a case report

INTRODUCTION

Stress cardiomyopathy is a condition of chest pain, breathlessness, abnormal heart rhythms and sometimes congestive heart failure or shock precipitated by intense mental or physical stress.

CASE PRESENTATION

A 64-year-old male with a known diagnosis of moderate-to-severe aortic stenosis and advised that valve replacement was not urgent, presented with acute pulmonary edema following extraordinary mental distress. The patient was misdiagnosed as having a "massive heart attack" and died when managed by a traditional protocol for acute myocardial infarction/coronary artery disease, irrespective of his known aortic stenosis.

CONCLUSION

Intense mental stress poses a considerable risk, particularly to patients with significant aortic stenosis. As described here, it can precipitate acute pulmonary edema. Importantly, effective management of acute pulmonary edema due to stress cardiomyopathy in patients with known aortic stenosis requires its distinction from acute pulmonary edema caused by an acute myocardial infarction. Treatment options include primarily urgent rhythm and/or rate control, as well as cautious vasodilation.

Hypertensive Emergency in Aortic Dissection and Thoracic Aortic Aneurysm-A Review of Management

Over the last few decades, treatment for aortic dissection and thoracic aortic aneurysms has evolved significantly with improvement in outcomes. Treatment paradigms include medical, endovascular and surgical options. As aortic dissection presents as a hypertensive emergency, diligent control of BP is of utmost importance in order to reduce the progression of dissection with possible aortic branch malperfusion. Treatment should begin on arrival to the emergency department and continues in the intensive care unit, endovascular suite or the operating room. Novel antihypertensive medications with improved pharmacological profile and improved surgical techniques, have improved the prognosis of patients with aortic aneurysm and/or aortic dissection. Nevertheless, morbidity and mortality remain high and hypertensive emergency poses a significant challenge in aortic dissection and thoracic aortic aneurysms.

Perioperative hypertension: a review of current and emerging therapeutic agents

Perioperative hypertension is a common problem encountered by anesthesiologists, surgeons, internists, and intensivists. Surprisingly, no randomized, placebo-controlled studies exist that show that the treatment of perioperative hypertension reduces morbidity or mortality. Nevertheless, perioperative hypertension requires careful management. While sodium nitroprusside and nitroglycerin are commonly used to treat these conditions, these agents are less than ideal. Intravenous beta blockers and calcium channel blockers have particular appeal in this setting.

Treatment of acute severe hypertension: current and newer agents

Approximately 72 million people in the US experience hypertension. Worldwide, hypertension may affect as many as 1 billion people and be responsible for approximately 7.1 million deaths per year. It is estimated that approximately 1% of patients with hypertension will, at some point, develop a hypertensive crisis. Hypertensive crises are further defined as either hypertensive emergencies or urgencies, depending on the degree of blood pressure elevation and presence of end-organ damage. Immediate reduction in blood pressure is required only in patients with acute end-organ damage (i.e. hypertensive emergency) and requires treatment with a titratable, short-acting, intravenous antihypertensive agent, while severe hypertension without acute end-organ damage (i.e. hypertensive urgency) is usually treated with oral antihypertensive agents. The primary goal of intervention in a hypertensive crisis is to safely reduce blood pressure. The appropriate therapeutic approach of each patient will depend on their clinical presentation. Patients with hypertensive emergencies are best treated in an intensive care unit with titratable, intravenous, hypotensive agents. Rapid-acting intravenous antihypertensive agents are available, including labetalol, esmolol, fenoldopam, nicardipine and sodium nitroprusside. Newer agents, such as clevidipine and fenoldopam, may hold considerable advantages to other available agents in the management of hypertensive crises. Sodium nitroprusside is an extremely toxic drug and its use in the treatment of hypertensive emergencies should be avoided. Similarly, nifedipine, nitroglycerin and hydralazine should not to be considered first-line therapies in the management of hypertensive crises because these agents are associated with significant toxicities and/or adverse effects.

Perioperative hypertension management

Perioperative hypertension is commonly encountered in patients that undergo surgery. While attempts have been made to standardize the method to characterize the intraoperative hemodynamics, these methods still vary widely. In addition, there is a lack of consensus concerning treatment thresholds and appropriate therapeutic targets, making absolute recommendations about treatment difficult. Nevertheless, perioperative hypertension requires careful management. When treatment is necessary, therapy should be individualized for the patient. This paper reviews the pharmacologic agents and strategies commonly used in the management of perioperative hypertension.

Hypertensive crises: challenges and management

Hypertension affects > 65 million people in the United States and is one of the leading causes of death. One to two percent of patients with hypertension have acute elevations of BP that require urgent medical treatment. Depending on the degree of BP elevation and presence of end-organ damage, severe hypertension can be defined as either a hypertensive emergency or a hypertensive urgency. A hypertensive emergency is associated with acute end-organ damage and requires immediate treatment with a titratable short-acting IV antihypertensive agent. Severe hypertension without acute end-organ damage is referred to as a hypertensive urgency and is usually treated with oral antihypertensive agents. This article reviews definitions, current concepts, common misconceptions, and pitfalls in the diagnosis and management of patients with acutely elevated BP as well as special clinical situations in which BP must be controlled.

The negative inotropic effect of esmolol on isolated cardiac muscle

OBJECTIVE

Esmolol is an ultra-short-term acting beta adrenergic blocker for intravenous use. The most common side effect is hypotension, which is often manageable by careful titration of the dose. We speculated whether esmolol had a direct negative inotropic effect on the cardiac muscle.

DESIGN

Papillary muscles and trabeculae were excised from guinea pig and pig hearts. Force production was recorded together with action potentials. Membrane currents were recorded in isolated myocytes. The effects of two concentrations of esmolol were tested (55 and 110 micromol/L).

RESULTS

Esmolol reduced action potential duration and plateau voltage, and decreased force production of isolated cardiac muscle. Voltage-clamp experiments from a holding potential of -40 mV and a step change to 0 mV showed a reduction in the inward current due to esmolol.

CONCLUSION

Apart from being a beta adrenergic blocker esmolol also exerts a direct negative inotropic effect on cardiac muscle due to its inhibition of the calcium current during the action potential.

Successful treatment of long QT syndrome-induced ventricular tachycardia with esmolol

Esmolol is a cardioselective beta-blocker with very rapid onset of action and short half-life due to its metabolism by blood-borne esterases. This unique profile among currently available beta-blockers renders esmolol highly useful in critical care situations. However, published experience with the use of esmolol in critically ill children is scant. The case of a 4-year-old boy with secondary long QT syndrome and ventricular tachycardia successfully treated with esmolol is presented.

Clinical review: the management of hypertensive crises

Hypertension is an extremely common clinical problem, affecting approximately 50 million people in the USA and approximately 1 billion individuals worldwide. Approximately 1% of these patients will develop acute elevations in blood pressure at some point in their lifetime. A number of terms have been applied to severe hypertension, including hypertensive crises, emergencies, and urgencies. By definition, acute elevations in blood pressure that are associated with end-organ damage are called hypertensive crises. Immediate reduction in blood pressure is required only in patients with acute end-organ damage. This article reviews current concepts, and common misconceptions and pitfalls in the diagnosis and management of patients with acutely elevated blood pressure.

Weathering the storm: beta-blockade and the potential for disaster in severe hyperthyroidism

Some patients with advanced thyrotoxicosis have occult cardiac dysfunction. The use of long-acting beta-blockers, traditional in the management of thyrotoxicosis, may have disastrous consequences in this setting. The following report documents the cardiovascular collapse and asystolic arrest of a patient with hyperthyroidism when treated with sotolol. Though the patient was successfully resuscitated, the long duration of action of sotolol necessitated prolonged inotropic and vasopressor support. A shorter acting beta-blocker, such as esmolol, theoretically may be a safer option.

The diagnosis and management of hypertensive crises

Severe hypertension is a common clinical problem in the United States, encountered in various clinical settings. Although various terms have been applied to severe hypertension, such as hypertensive crises, emergencies, or urgencies, they are all characterized by acute elevations in BP that may be associated with end-organ damage (hypertensive crisis). The immediate reduction of BP is only required in patients with acute end-organ damage. Hypertension associated with cerebral infarction or intracerebral hemorrhage only rarely requires treatment. While nitroprusside is commonly used to treat severe hypertension, it is an extremely toxic drug that should only be used in rare circumstances. Furthermore, the short-acting calcium channel blocker nifedipine is associated with significant morbidity and should be avoided. Today, a wide range of pharmacologic alternatives are available to the practitioner to control severe hypertension. This article reviews some of the current concepts and common misconceptions in the management of patients with acutely elevated BP.

Advances in pharmacotherapy: treatment of hypertensive crisis

A hypertensive crisis can be caused by many factors. Frequently, the mechanism involved is complex and highly variable among patients. Without drug therapy, this condition is associated with very high mortality and morbidity. There are a number of oral and intravenous hypotensive agents available, which can effectively control blood pressure in a hypertensive crisis. The relative advantages and disadvantages of each treatment option is discussed.

Esmolol in the Treatment of Multifocal Atrial Tachycardia

Multifocal atrial tachycardia (MAT) is a supraventricular tachydysrhythmia precipitated by a number of pharmacologic and physiologic disturbances. Corrections of these disturbances should take precedence in the treatment of MAT.

Use of esmolol to control autonomic instability of tetanus

Tetanus is often accompained by autonomic instability, rendering hemodynamic management difficult. Death is frequently secondary to an inability to control this instability. A variety of modalities have been used to stabilize the cardiovascular system, but all are not ideal. Esmolol offers theoretical advantages over other modalities. We report a case of severe tetanus in which a continuous infusion of esmolol was effective in controlling the autonomic instability.

Experience with esmolol for the treatment of cocaine-associated cardiovascular complications

The authors report their experience using esmolol, an ultra-short acting beta-adrenergic antagonist, for the treatment of seven patients with cocaine-associated cardiovascular complications. No consistent hemodynamic benefit was found with the use of this drug. Although there was a decline in mean heart rate of 23% (range 0% to 35%), they were unable to show a consistent antihypertensive response. Adverse effects occurred in three patients. This included one patient with a marked exacerbation of hypertension and one who became hypotensive. Another patient developed emesis and lethargy during esmolol therapy and required endotracheal intubation. They do not recommend the routine use of esmolol for cocaine cardiotoxicity.

Treatment of caffeine toxicity with esmolol

We present the case of a 58-year-old woman who ingested more than 35 g of caffeine in a suicide attempt. She manifested all the clinical symptoms and signs of caffeine toxicity. Esmolol, an ultrashort-acting beta 1-selective antagonist, controlled her multiple dysrhythmias and symptoms of sympathetic nervous system hyperstimulation. We suggest the use of esmolol for treatment of dysrhythmias secondary to caffeine toxicity; to the best of our knowledge, the use of esmolol has not been reported for this purpose.