Norepinephrine-induced left ventricular dysfunction in anesthetized and conscious, sedated dogs

Histologic characterization of spontaneous catecholamine-induced cardiomyopathy in laboratory New Zealand White rabbits

Catecholamine-induced cardiomyopathy (CCM) is an entity associated with increased levels of catecholamines causing subendocardial and papillary muscle cardiomyocyte degeneration and necrosis. In 2020, 49 autopsies from early rabbit deaths in a colony used for medical device biocompatibility studies were submitted for microscopic examination. Of the 49 rabbits, 26 had histologic changes consistent with CCM. No common stressor for CCM was determined in affected rabbits. Animals were generally male, were 12-16-wk-old, and were found dead or had bloating, lethargy, and/or diarrhea. Those observed with clinical signs were euthanized and autopsied per the organization's standard operating procedures. Heart lesions consisted of various degrees of apical subendocardial myocardial degeneration and necrosis. Common non-cardiac lesions included pulmonary congestion and edema, hepatic congestion and centrilobular hepatocellular degeneration, and/or variable intestinal submucosal edema.

Preclinical models of congestive heart failure, advantages, and limitations for application in clinical practice

Congestive heart failure (CHF) has increased over the years, in part because of recent progress in the management of chronic diseases, thus contributing to the maintenance of an increasingly aging population. CHF represents an unresolved health problem and therefore the establishment of animal models that recapitulates the complexity of CHF will become a critical element to be addressed, representing a serious challenge given the complexity of the pathogenesis of CHF itself, which is further compounded by methodological biases that depend on the animal species in use. Animal models of CHF have been developed in many different species, with different surgical procedures, all with promising results but, for the moment, unable to fully recapitulate the human disease. Large animal models often provide a more promising reality, with all the difficulties that their use entails, and which limit their performance to fewer laboratories, the costly of animal housing, animal handling, specialized facilities, skilled methodological training, and reproducibility as another important limiting factor when considering a valid animal model versus potentially better performing alternatives. In this review we will discuss the different animal models of CHF, their advantages and, above all, the limitations of each procedure with respect to effectiveness of results in terms of clinical application.

Primary Graft Dysfunction after Heart Transplantation - Unravelling the Enigma

Primary graft dysfunction (PGD) remains the main cause of early mortality following heart transplantation despite several advances in donor preservation techniques and therapeutic strategies for PGD. With that aim of establishing the aetiopathogenesis of PGD and the preferred management strategies, the new consensus definition has paved the way for multiple contemporaneous studies to be undertaken and accurately compared. This review aims to provide a broad-based understanding of the pathophysiology, clinical presentation and management of PGD.

Role of PI3K/AKT/mTOR Pathway Associated Oxidative Stress and Cardiac Dysfunction in Takotsubo Syndrome

INTRODUCTION

Takotsubo syndrome (TTS) is a stress-induced cardiomyopathy, but the accurate cause of this syndrome is still unknown.

METHODS

β-adrenergic agonist isoproterenol (ISO) is used to establish the TTS rats model. TTS rats were treated with or without LY294002 or Rapamycin. The rat cardiomyoblast cell line H9C2 was subjected to infect with constitutively active Akt (myr-Akt) or dominant-negative mutant Akt (dn-Akt) and then, treated with ISO. Cell apoptosis was assessed using the Bax/ Bcl-2 ratio. In addition, reactive oxygen species (ROS) levels were measured using dihydroethidium (DHE). Mitochondrial superoxide generation and membrane potential were assayed by MitoSOX and JC-1 fluorescence intensity.

RESULTS

ISO might induce the erratic acute cardiac dysfunction and overexpression of PI3K/AKT/mTOR. Moreover, it also increased the oxidative stress and apoptosis in TTS rats. The Akt inhibitor significantly reversed the cardiac injury effect, which triggered by ISO treatment. In H9C2 cells, the inhibition of Akt provides a protective role against ISO-induced injury by reducing oxidative stress, apoptosis and mitochondrial dysfunction.

CONCLUSION

This study provided new insight into the protective effects of myocardial dysfunction in TTS rats via chronic inhibition of the PI3K/AKT/mTOR expression, which could reduce mitochondrial ROS and oxidative stress-induced apoptosis. PI3K/AKT/mTOR inhibitor could be a therapeutic target to treat cardiovascular dysfunction induced by stress cardiomyopathy.

Epinephrine soaked tampons induced transient acute dilated cardiomyopathy during FESS procedure

Background

Epinephrine, in all modes of use, may pose a wide range of cardiotoxic events, ranging from sinus tachycardia to heart failure, life threatening arrhythmias, and even death. Because of daily and extensive use of epinephrine, these unusual and rare events tend to be forgotten by physicians. We present a case of dilated cardiomyopathy that developed following routine use of epinephrine-impregnated tampons during function endoscopic sinus (FESS) surgery.

Case presentation

A healthy, 24-year-old man with no family history of heart disease has undergone elective surgery under general anesthesia to repair the paranasal sinuses using endoscopic approach. During surgery, soon after being treated with 1: 1000 diluted epinephrine-soaked tampons, an hypertensive crisis was noticed followed by pulseless electrical activity. An extensive examination led to the diagnosis of non-ischemic dilated cardiomyopathy. After several days of heart failure medical therapy, complete resolution of all structural and functional changes was achieved.

Conclusion

In our case, we present an unusual and rare event of acute dilated cardiomyopathy following the use of epinephrine-soaked tampons during elective FESS surgery. A prompt response was observed after several days of heart failure treatment. Awareness of the epinephrine cardiotoxic potential even in the form of soaked tampons is essential for proper diagnosis and prompt treatment.

Stress (Takotsubo) Cardiomyopathy: A Review of Its Pathophysiology, Manifestations, and Factors That Affect Prognosis

Stress (Takotsubo) cardiomyopathy (SC) is becoming an increasingly recognized syndrome, previously underdiagnosed due to its similar presentation to acute coronary syndrome (ACS). With advancements in imaging and diagnostic tools, our ability to recognize, diagnose and subsequently manage SC has advanced as well. Multiple diagnostic criteria have been created for the diagnosis of SC. While the diagnosis of SC does not always require imaging, advanced imaging can aid in the diagnosis of SC in unclear cases. However, due to the severity of ACS and the consequences of missing that diagnosis, SC is still typically a diagnosis of exclusion once ACS has been ruled out on cardiac catheterization. Our understanding of the pathogenesis of SC is still evolving. While catecholamine surges are widely believed to be the precipitating cause of SC, the exact mechanism for how catecholamine surges lead to ventricular dysfunction is still being debated. Understanding the mechanism behind ventricular dysfunction in SC can potentially provide the basis for treatment. Different stressors may lead to different variants of cardiomyopathy, with different portions of the ventricles affected. Treatment of SC is largely supportive and therefore should be tailored to the patient's individual needs based on the severity of presentation. Both the underlying stressor and the variant of SC affect time to recovery and mortality. Many patient factors can impact prognosis as well. Even after initial hospital discharge for SC, long-term risks do exist, including the risk for recurrent SC. Only angiotensin-converting enzyme inhibitors have been shown to reduce the recurrence of SC.

Comparison of midazolam and butorphanol combined with ketamine or dexmedetomidine for chemical restraint in howler monkeys (Alouatta guariba clamitans) for vasectomy

BACKGROUND

This study evaluated and compared cardiorespiratory and blood gas parameters, as well as sedation, analgesia and recovery of two protocols: ketamine (10 mg/kg) or dexmedetomidine (10 μg/kg), with midazolam (0.5 mg/kg) and butorphanol (0.3 mg/kg), IM (KBM and DBM, respectively) in brown howler monkeys (Alouatta guariba clamitans).

MATERIAL AND METHODS

Twelve brown howler monkeys were selected in two groups and evaluated for cardiorespiratory parameters and sedation, from 5-30 minutes after latency. Blood gas and arterial lactate were taken at 5 and 30 minutes. In the end, time and quality of recovery were evaluated.

RESULTS

The HR in DBM group was significantly lower at all times. The sedation score was higher in DBM. Recovery in DBM was faster. All animals had moderate hypoxaemia.

CONCLUSION

Both protocols produce satisfactory anaesthesia and analgesia, but DBM provides deeper sedation with faster recovery. Oxygen supplementation is recommended in both due to hypoxaemia.

Primary graft dysfunction after heart transplantation: a thorn amongst the roses

Primary graft dysfunction (PGD) remains the leading cause of early mortality post-heart transplantation. Despite improvements in mechanical circulatory support and critical care measures, the rate of PGD remains significant. A recent consensus statement by the International Society of Heart and Lung Transplantation (ISHLT) has formulated a definition for PGD. Five years on, we look at current concepts and future directions of PGD in the current era of transplantation.

Cardiovascular reactivity to emotional stress: The hidden challenge for pets in the urbanized environment

Emotional stress is currently considered an important risk factor for cardiovascular diseases. Experimental evidence clearly shows robust autonomic cardiovascular effects in animals exposed to stress stimuli. Considering the remarkable variability of stressors, the urban environment can pose a severe challenge to cardiovascular control. Interestingly, pet ownership is indicated as an efficient non-pharmacological therapy to attenuate stress effects that can reduce the risk of cardiovascular disease. However, the risk of cardiovascular diseases in pets themselves living in urban environment has not received attention it deserves. Here, we review the central mechanisms involved in the autonomic cardiovascular response to emotional stress. Next, we discuss experimental evidence showing the cardiovascular effects produced by emotional stressors in animals, aiming to establish a parallel with common urban stressors. Association of additional risk factors such as sedentarism, obesity and ambient temperature are also considered. Our aim is to identify and raise awareness of the risk of cardiovascular disease in pets exposed to quotidian emotional stressors present in the urban environment.

Levels of Catecholamines in the Plasma of Patients with Cardiopulmonary Arrest

So far, there remains a controversy regarding the efficacy of epinephrine (Ep) in patients with cardiopulmonary arrest (CPA). In this study, we evaluated the importance of the plasma levels of catecholamines prior to the administration of Ep in patients with CPA. Patients with out-of-hospital cardiac arrest (OHCA) who were transferred to Gunma University Hospital were enrolled prospectively between July 2014 and July 2017. The levels of catecholamines [Ep, norepinephrine (NEp), and dopamine] and vasopressin (antidiuretic hormone) in the plasma were measured using blood samples of cardiogenic patients with OHCA not treated with Ep. Patients were divided into two groups: the return of spontaneous circulation [ROSC (+) ] group and the no return of spontaneous circulation [ROSC (-) ] group. The plasma levels of these agents and the conditions of resuscitation were compared between these two groups. 48 patients with cardiogenic CPA had not been treated with Ep prior to obtaining the blood samples. The ROSC (+) and ROSC (-) groups included 14 and 34 patients, respectively. The frequency of prehospital defibrillation was significantly higher in the ROSC (+) group. However, the prehospital resuscitation time was significantly shorter in the ROSC (+) group. Moreover, the levels of Ep and NEp in the plasma were significantly lower in the ROSC (+) group. The increased levels of Ep in the plasma may not be associated with the acquisition of ROSC in patients with cardiogenic CPA.

Iatrogenic Takotsubo Cardiomyopathy Secondary to Norepinephrine by Continuous Infusion for Shock

Takotsubo cardiomyopathy is a condition characterized by transient left ventricular systolic and diastolic dysfunction, with a possible direct causal role of catecholamine in its pathophysiology. We present a case of a woman with shock and adrenal insufficiency in whom Takotsubo cardiomyopathy developed after treatment with norepinephrine. This case confirms the direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy. An 82-year-old woman presented with asthenia, anorexia, nausea and abdominal pain. The patient had been on chronic corticosteroid therapy until 3 months before, when she underwent abdominal surgery and corticosteroids were stopped. She now presented with acute kidney injury, hyponatremia and hyperkalemia and shock. A norepinephrine continuous infusion was administered to maintain a mean arterial pressure over 65 mmHg. An echocardiogram showed severe hypokinesis in the apical segments and hyperdynamic basal segments, with an ejection fraction of 25%. Plasma cortisol level was 4.5 μg/dL (reference range 5-25). Corticosteroid therapy was begun and norepinephrine was tapered and stopped. A new echocardiogram showed normalization of cardiac wall motion and an ejection fraction of 70%. This case highlights the importance of the correction of the cause of shock, as well as the risks associated with the use of norepinephrine if hypotension is severe or if it persists despite fluid administration, as usually recommended. It also confirms the direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy. To the best of our knowledge, this is the first report of stress-induced cardiomyopathy secondary to norepinephrine by continuous infusion for shock.

LEARNING POINTS

Takotsubo cardiomyopathy is a condition characterized by transient left ventricular dysfunction of the apex and midventricle in the absence of attributable coronary artery disease.In patients with shock and adrenal insufficiency, who can be erroneously interpreted as septic shock, Takotsubo cardiomyopathy can develop after treatment with norepinephrine.In the management of shock, there are risks associated with recommending the use of norepinephrine if hypotension is severe or if it persists despite fluid administration, when the cause of shock is other than septic shock and is not corrected.There is a direct causal role of catecholamine in the pathophysiology of Takotsubo cardiomyopathy.

Vascular disease in cocaine addiction

Cocaine, a powerful vasoconstrictor, induces immune responses including cytokine elevations. Chronic cocaine use is associated with functional brain impairments potentially mediated by vascular pathology. Although the Crack-Cocaine epidemic has declined, its vascular consequences are increasingly becoming evident among individuals with cocaine use disorder of that period, now aging. Paradoxically, during the period when prevention efforts could make a difference, this population receives psychosocial treatment at best. We review major postmortem and in vitro studies documenting cocaine-induced vascular toxicity. PubMed and Academic Search Complete were used with relevant terms. Findings consist of the major mechanisms of cocaine-induced vasoconstriction, endothelial dysfunction, and accelerated atherosclerosis, emphasizing acute, chronic, and secondary effects of cocaine. The etiology underlying cocaine's acute and chronic vascular effects is multifactorial, spanning hypertension, impaired homeostasis and platelet function, thrombosis, thromboembolism, and alterations in blood flow. Early detection of vascular disease in cocaine addiction by multimodality imaging is discussed. Treatment may be similar to indications in patients with traditional risk-factors, with few exceptions such as enhanced supportive care and use of benzodiazepines and phentolamine for sedation, and avoiding β-blockers. Given the vascular toxicity cocaine induces, further compounded by smoking and alcohol comorbidity, and interacting with aging of the crack generation, there is a public health imperative to identify pre-symptomatic markers of vascular impairments in cocaine addiction and employ preventive treatment to reduce silent disease progression.

Drug-Induced Takotsubo Cardiomyopathy

BACKGROUND

The most plausible hypothesis for takotsubo cardiomyopathy (TCM) is a catecholamine surge. Direct administration of catecholamines or medications causing catecholamine surge is frequently used in clinical practice.

METHODS

A Medline/PubMed database search was conducted for case reports or series of drug-induced TCM. All reported cases of drug-induced TCM were systemically identified and analyzed.

RESULTS

We identified 157 cases of drug-induced TCM. Fifty-seven (36.3%) cases were related to the administration of exogenous catecholamines. In 50 (31.9%) other cases, there was potential adrenergic effect. This included drugs with adrenergic vasoconstriction properties (3.2%), hyperadrenergic state due to alcohol or opioid withdrawal (7.7%), inhibitors of catecholamine reuptake (14.7%), anaphylactic reaction that is accompanied by catecholamine release (3.2%), and psychological or somatic stress coinciding with the administration of a drug that was thought to be the culprit (3.2%). Overall, 68.2% of these drug-induced TCM cases were catecholamine related. In 14 (8.9%) cases, the likely etiology of cardiomyopathy was chemotherapy-induced coronary vasospasm.

CONCLUSION

Our systematic review showed that over two-thirds of drug-induced TCM cases were due to direct or indirect catecholamine stimulation. The lowest effective dose and shortest duration of catecholamines should be utilized, and alternative therapies should be considered if feasible.

Takotsubo cardiomyopathy after administration of norepinephrine

Stress-induced cardiomyopathy is a syndrome of transient cardiac dysfunction with no clear pathophysiology. It is thought to be secondary to catecholamine surge. The mechanism by which catecholamine can induce transient cardiac dysfunction is unknown. We present a case of a patient who developed stress-induced cardiomyopathy after she was administered norepinephrine due to a nursing error.

Adrenergic Inhibition with Dexmedetomidine to Treat Stress Cardiomyopathy during Alcohol Withdrawal: A Case Report and Literature Review

Stress (Takotsubo) cardiomyopathy is a form of reversible left ventricular dysfunction with a heightened risk of ventricular arrhythmia thought to be caused by high circulating catecholamines. We report a case of stress cardiomyopathy that developed during severe alcohol withdrawal successfully treated with dexmedetomidine. The case involves a 53-year-old man with a significant history of alcohol abuse who presented to a teaching hospital with new-onset seizures. His symptoms of acute alcohol withdrawal were initially treated with benzodiazepines, but the patient later developed hypotension, and stress cardiomyopathy was suspected based on ECG and echocardiographic findings. Adjunctive treatment with the alpha-2-adrenergic agonist, dexmedetomidine, was initiated to curtail excessive sympathetic outflow of the withdrawal syndrome, thereby targeting the presumed pathophysiology of the cardiomyopathy. Significant clinical improvement was observed within one day of initiation of dexmedetomidine. These findings are consistent with other reports suggesting that sympathetic dysregulation during alcohol withdrawal produces ideal pathobiology for stress cardiomyopathy and leads to ventricular arrhythmogenicity. Stress cardiomyopathy should be recognized as a complication of alcohol withdrawal that significantly increases cardiac-related mortality. By helping to correct autonomic dysregulation of the withdrawal syndrome, dexmedetomidine may be useful in the treatment of stress-induced cardiomyopathy.

Kidney transplantation in children with decreased left ventricular systolic function: a Midwest Pediatric Nephrology Consortium study

BACKGROUND

Left ventricular (LV) systolic dysfunction is a relatively uncommon but serious complication of pediatric chronic kidney disease, and may be related to uremia and uncontrolled hypertension. There is limited information on the strategy for managing these children. In some cases, combined heart-kidney transplant may be considered or kidney transplant delayed until cardiac function improves. It is unknown whether these patients are at increased risk for poor outcomes after kidney transplantation.

METHODS

We conducted a retrospective, multicenter study on the outcomes of children with severe and symptomatic cardiomyopathy who underwent kidney transplantation.

RESULTS

Eleven patients receiving maintenance dialysis with systolic dysfunction underwent kidney transplantation without simultaneous heart transplant. Nine patients had congestive heart failure in the pre-transplant period. There were no identified complications post-transplant related to the underlying cardiac dysfunction. LV systolic function normalized in all patients and the mean shortening fraction increased from 19.0 ± 4.6 % to 32.0 ± 4.4 % (p < 0.0001).

CONCLUSIONS

Kidney transplantation should be considered for children receiving maintenance dialysis with severe LV dysfunction.

The role of nuclear cardiac imaging in redefining neurogenic stunned myocardium in subarachnoid hemorrhage: a deeper look into the heart

Subarachnoid hemorrhage may be complicated by neurogenic stunned myocardium, a catecholamine-induced transient cardiomyopathy that displays a wide clinical spectrum of cardiac abnormalities, including electrocardiographic changes, arrhythmias, myocardial necrosis, and left ventricular systolic and diastolic dysfunction. However, less is known about the cardiac metabolic consequences of acute subarachnoid hemorrhage. Prunet and coworkers' recent study provides scintigraphic evidence suggesting that glucose metabolism and sympathetic cardiac innervation are severely and globally depressed during the acute phase of the disease. Metabolic and innervation abnormalities are largely overlapped and are probably not causally related to myocardial ischemia, suggesting that impaired glucose metabolism is probably neurogenic in nature. The scintigraphic defects seem to reverse slowly, within months of the onset of cerebral bleeding. Interestingly, scintigraphic evidence of metabolic myocardial alterations may exist even in the absence of clinical features of cardiac disease, possibly representing a subclinical type of neurogenic stunned myocardium.

Takotsubo cardiomyopathy, a two-stage recovery of left ventricular systolic and diastolic function as determined by cardiac magnetic resonance imaging

AIMS

Takotsubo cardiomyopathy (TTC) is an entity mimicking acute myocardial infarction, characterized by transient severe systolic heart failure. Echocardiographic studies suggest that diastolic dysfunction is present in TTC at presentation; however, no reports exist regarding the time course of left ventricular (LV) recovery. This study describes the recovery of LV systolic and diastolic function in TTC. We hypothesized that, in TTC, there is diastolic dysfunction at admission, and that recovery is delayed compared with systolic function.

METHODS AND RESULTS

We enrolled (consecutively 2010-12) 16 patients (mean age 66, range 39-84 years) diagnosed with TTC and 20 healthy matched controls. We performed cardiac magnetic resonance imaging (CMR) at admission, pre-discharge, and 3-month follow-up. Diastolic function was assessed by LV peak filling rate (LVPFR) and left atrial (LA) emptying volumes. At admission, LV ejection fraction was low, increased at pre-discharge (37 ± 6 vs. 58 ± 6%, P < 0.001), and normalized at follow-up (to 65 ± 5%, P = 0.01). LVPFR did not increase during hospitalization (80 ± 3 vs. 89 ± 4 mL/s/m(2), P = 0.21), but was normalized at follow-up (to 206 ± 19, P < 0.001; controls, 214 ± 13, P = 0.23). During hospitalization, LA passive emptying volume remained low (6 ± 2 vs. 8 ± 3 mL/m(2), P = 0.05) and LA active emptying volume remained high (17 ± 3 vs. 16 ± 3 mL/m(2), P = 0.71), whereas LA conduit volume increased (7 ± 3 vs. 23 ± 4 mL/m(2), P < 0.001). T2-weighted imaging demonstrated non-coronary distributed apical oedema without contrast enhancement.

CONCLUSION

Patients with TTC undergo fast systolic recovery. However, at discharge, profound diastolic dysfunction is demonstrated by CMR. At follow-up, both LV systolic and diastolic function is normalized in patients with recovered TTC.

Catecholamine induced cardiomyopathy in pheochromocytoma

Catecholamine induced cardiomyopathy in the setting of pheochromocytoma is an unusual clinical entity. Earlier studies have reported left ventricular dysfunction in around 10% of subjects with pheochromocytoma.[1] Catecholamine induced vasoconstriction, direct toxic effect of byproducts of catecholamine degradation and direct receptor-mediated mechanisms are thought to contribute to cardiomyopathy in subjects with pheochromocytoma. The presentation remains a diagnostic challenge as patients may already have hypertensive heart disease and acute coronary syndrome on account of uncontrolled secondary hypertension. We report a case of a 42-year-old male, who presented with features of pheochromocytoma induced cardiomyopathy.

Drug-induced takotsubo cardiomyopathy

Takotsubo cardiomyopathy (TTC), also known as stress cardiomyopathy, is an increasingly recognized clinical syndrome of acute reversible left ventricular dysfunction precipitated by intense emotional or physical stress. Excessive sympathetic stimulation is believed to be central to the pathogenesis of this condition; thus, drugs with sympathetic effect could precipitate TTC. This review outlines previous reports regarding drugs that may induce TTC. Some reports link the use of the drug-primarily associated with sympathetic overstimulation-with the development of TTC Consequently, drug-induced TTC should be considered in patients diagnosed with TTC.

Stress cardiomyopathy: diagnosis, pathophysiology, management, and prognosis

Stress cardiomyopathy is now a well-recognized reversible cardiomyopathy, with a clinical presentation mimicking Acute Coronary syndrome in the absence of significant coronary artery disease. It is often encountered in postmenopausal females and is usually precipitated by acute emotional or physical stressors. In this review, we have attempted to summarize relevant data regarding diagnosis, typical and atypical presentations, pathophysiology, management options, and prognosis. Typically, patients present with chest pain and shortness of breath, transient electrocardiographic changes, moderate troponin elevation, and are found to have wall motion abnormalities (apical and midventricular akinesis with preserved basal segment systolic function) without obstructive coronary lesions, with complete resolution in next few weeks. The precise pathophysiology remains unclear, but excessive catecholamine stimulation, metabolic disturbances, and dysfunction of microcirculation are thought to be the underlying mechanisms.

Hypertrophic obstructive cardiomyopathy masked by tako-tsubo syndrome: a case report

Introduction. Left ventricular outflow obstruction might be part of the pathophysiological mechanism of Tako-tsubo cardiomyopathy. This obstruction can be masked by Tako-tsubo cardiomyopathy and diagnosed only by followup. Case Presentation. A 70-year-old female presented with Tako-tsubo cardiomyopathy and masked obstructive hypertrophic cardiomyopathy at presentation. Conclusion. Tako-tsubo cardiomyopathy typically presents like an acute MI and is characterized by severe, but transient, regional left ventricular systolic dysfunction. Prompt evaluation of the coronary status is, therefore, mandatory. The prognosis under medical treatment of heart failure symptoms and watchful waiting is favourable. Previous studies showed that LVOT obstruction might be part of the pathophysiological mechanism of TCM. This paper supports this theory. However, TCM may also mask any preexisting LVOT obstruction.

Neurogenic stunned myocardium and takotsubo cardiomyopathy are the same syndrome: a pooled analysis

Neurogenic stunned myocardium (NSM) and Takotsubo cardiomyopathy (TCM) are two syndromes that coexist in the medical literature. They share many common features. We hypothesized that they, in fact, represent the same syndrome. We collected and analyzed case reports of transient left ventricular (LV) dysfunction in neurologic conditions. Cases were compared based on the diagnosis and then based on the pattern of wall motion abnormality. Of 112 cases, 61 were diagnosed as TCM and 37 as NSM, and in 14 cases, the authors used both terms. Overall, the patients with NSM were younger, and the severity of LV systolic dysfunction and timing of recovery was similar, as well as the prevalence of cardiac enzyme elevation. Pulmonary edema on presentation was more prevalent in patients with NSM while chest pain and ST-segment elevation was more common in patients with TCM. While only regional, predominantly apical, wall motion abnormality was described in TCM, some patients in the NSM group had global LV dysfunction. NSM and TCM likely share the same mechanism and pathologic substrate. Their natural course is almost identical. They both likely represent the same syndrome of stress-induced cardiomyopathy. Current definition of stress-induced cardiomyopathy includes only regional wall motion abnormalities. It should be expanded to include all varieties of wall motion abnormalities including global hypokinesis.

Stress cardiomyopathy

Recently, an increasing number of cases of stress cardiomyopathy, mainly occurring in elderly women, have been documented in many parts of the world. In Japan, this disease is known as takotsubo cardiomyopathy (named after the fishing pot used for trapping octopus). Symptoms of this condition are akin to those of acute myocardial infarction, but no obstructive lesions are found in the coronary arteries, and left ventricular apical ballooning is present. Stress cardiomyopathy is now a well-recognized cause of acute heart failure, lethal ventricular arrhythmias, and ventricular rupture. Although the precise mechanism of onset of this condition is still controversial, two major pathogenic mechanisms have been proposed: catecholamine cardiotoxicity and neurogenic stunned myocardium. We summarize the findings of studies conducted to date on stress cardiomyopathy-from bench to bedside and bedside to bench.

Mechanisms of stress (Takotsubo) cardiomyopathy

Stress cardiomyopathy, also referred to as Takotsubo cardiomyopathy, transient apical ballooning or broken heart syndrome, is a disorder associated with transient left ventricular dysfunction. Symptoms include acute chest pain and dyspnea accompanied by electrocardiographic changes, such as ST-segment elevation and T-wave inversions, minimal elevation of cardiac enzyme levels and transient wall-motion abnormalities in the absence of substantial coronary artery obstruction. Complete recovery of contractile function has been documented in nearly all cases, but the mechanisms of disease remain unclear and the cause has not been established. Coronary artery vasospasm, microcirculation dysfunction, and transient obstruction of the left ventricular outflow tract have been proposed as possible causes of this disorder. An excessive release of catecholamines also seems to have a pivotal role in the development of stress cardiomyopathy. This Review summarizes published data on stress cardiomyopathy, focusing primarily on the most likely causes of this cardiac entity.

Comparison of cardiac, hepatic, and renal effects of arginine vasopressin and noradrenaline during porcine fecal peritonitis: a randomized controlled trial

Introduction

Infusing arginine vasopressin (AVP) in vasodilatory shock usually decreases cardiac output and thus systemic oxygen transport. It is still a matter of debate whether this vasoconstriction impedes visceral organ blood flow and thereby causes organ dysfunction and injury. Therefore, we tested the hypothesis whether low-dose AVP is safe with respect to liver, kidney, and heart function and organ injury during resuscitated septic shock.

Methods

After intraperitoneal inoculation of autologous feces, 24 anesthetized, mechanically ventilated, and instrumented pigs were randomly assigned to noradrenaline alone (increments of 0.05 μg/kg/min until maximal heart rate of 160 beats/min; n = 12) or AVP (1 to 5 ng/kg/min; supplemented by noradrenaline if the maximal AVP dosage failed to maintain mean blood pressure; n = 12) to treat sepsis-associated hypotension. Parameters of systemic and regional hemodynamics (ultrasound flow probes on the portal vein and hepatic artery), oxygen transport, metabolism (endogenous glucose production and whole body glucose oxidation derived from blood glucose isotope and expiratory ¹³CO₂/¹²CO₂ enrichment during 1,2,3,4,5,6-¹³C₆-glucose infusion), visceral organ function (blood transaminase activities, bilirubin and creatinine concentrations, creatinine clearance, fractional Na⁺ excretion), nitric oxide (exhaled NO and blood nitrate + nitrite levels) and cytokine production (interleukin-6 and tumor necrosis factor-α blood levels), and myocardial function (left ventricular dp/dt_max and dp/dt_min) and injury (troponin I blood levels) were measured before and 12, 18, and 24 hours after peritonitis induction. Immediate post mortem liver and kidney biopsies were analysed for histomorphology (hematoxylin eosin staining) and apoptosis (TUNEL staining).

Results

AVP decreased heart rate and cardiac output without otherwise affecting heart function and significantly decreased troponin I blood levels. AVP increased the rate of direct, aerobic glucose oxidation and reduced hyperlactatemia, which coincided with less severe kidney dysfunction and liver injury, attenuated systemic inflammation, and decreased kidney tubular apoptosis.

Conclusions

During well-resuscitated septic shock low-dose AVP appears to be safe with respect to myocardial function and heart injury and reduces kidney and liver damage. It remains to be elucidated whether this is due to the treatment per se and/or to the decreased exogenous catecholamine requirements.

The effects of hormone resuscitation on cardiac function and hemodynamics in a porcine brain-dead organ donor model

We compared the effects of hormone resuscitation (HR) with a norepinephrine-based protocol on cardiac function, hemodynamics and need for vasopressor support after brain death in a porcine model. Following brain death induction, animals were treated with norepinephrine and fluids for 3 h. In the following 3 h, they continued on norepinephrine and fluids (control) or received additional HR (triiodothyronine, methylprednisolone, vasopressin, insulin). Data were collected pre-brain death, 3 and 6 h post-brain death. At 6 h, median norepinephrine use was higher in controls (0.563 vs. 0 microg/kg/min; p < 0.005), with 6/8 HR animals weaned off norepinephrine compared with 0/9 controls. Mean arterial pressure was higher in HR animals at 6 h (74 +/- 17 vs. 54 +/- 14 mmHg; p < 0.05). Cardiac contractility was also significantly higher in HR animals at 6 h (stroke work index 1.777 vs. 1.494). After collection of 6 h data, all animals were placed on the same low dose of norepinephrine. At 6.25 h, HR animals had higher stroke work (3540 +/- 1083 vs. 1536 +/- 702 mL.mmHg; p < 0.005), stroke volume (37.2 +/- 8.2 vs. 21.5 +/- 9.8 mL; p < 0.01) and cardiac output (5.8 +/- 1.4 vs. 3.2 +/- 1.2 L/min; p < 0.005). HR in a porcine model of brain death reduces norepinephrine requirements, and improves hemodynamics and cardiac function. These results support the use of HR in the management of the brain-dead donor.

Transient left ventricular dysfunction under severe stress: brain-heart relationship revisited

PURPOSE

Transient left ventricular dysfunction in patients under emotional or physical stress, also known as tako-tsubo-like left ventricular dysfunction, has been recently been recognized as a distinct clinical entity. The aims of this review are to define this phenomenon and to explore its similarities to the left ventricular dysfunction seen in patients with acute brain injury.

METHODS

MEDLINE database, bibliographies of each citation for relevant articles, and consultation with clinical experts were used to examine the clinical picture of tako-tsubo-like left ventricular dysfunction.

RESULTS

We identified case series and a systematic review that report on patients with this syndrome. This phenomenon occurs predominantly in female patients, presenting with a variety of ST-T segment changes and mildly elevated cardiac enzymes that mimic an acute coronary syndrome. The left ventricular dysfunction, typically showing a hyperkinetic basal region and an akinetic apical half of the ventricle, occurs in the absence of obstructed epicardial coronary arteries. The ventricular dysfunction usually resolves within weeks with a generally favorable prognosis. This phenomenon has similarities to that seen in patients with acute brain injury with regard to clinical presentation, pathology, and its reversible nature.

CONCLUSIONS

Transient left ventricular dysfunction occurs in the absence of obstructive epicardial coronary artery disease. In its broadest sense, this phenomenon may encompass a range of disorders including left ventricular dysfunction after central nervous system injury.

Effects of catecholamine application to brain-dead donors on graft survival in solid organ transplantation

BACKGROUND

In a recent single-center study, donor use of catecholamines was identified to reduce kidney allograft rejection. This study investigates the effects of donor employment of adrenergic agents on graft survival in a large data base, including liver and heart transplants.

METHODS

The study was based on the registry of the Eurotransplant International Foundation including 2415 kidney, 755 liver, and 720 heart transplants performed between January 1 and December 31, 1993. A total of 1742 donor record forms referring to the cadaveric donor activities in 1993 were systematically reviewed with regard to employment of adrenergic agents. Catecholamine use was simply coded dichotomously and divided into three strata according to zero, single, and combined application. Multivariate Cox regression including age, gender, cause of brain death, cold ischemia, HLA-mismatching, number of previous transplants, and urgency in liver transplants was applied for statistical analysis.

RESULTS

Donor employment of catecholamines was associated with increased 4-year graft survival after kidney transplantation (hazard ratio [HR], 0.85; 95% confidence interval [95% CI], 0.74-0.98). The benefit is conferred in a dose-dependent manner and compares in quantitative terms with prospective HLA matching on class I and class II antigens (HR, 0.90; 95% CI, 0.84-0.97). Use of norepinephrine was predictive of initial nonfunction after heart transplantation (HR, 1.66; 95% CI, 1.14-2.43), but did not compromise liver grafts (HR, 0.94; 95% CI, 0.67-1.32).

CONCLUSIONS

Optimizing the management of brain-dead organ donors, including the possibility of selective administration of adrenergic agents, may provide a major benefit on graft survival without adverse side effects for the recipients. Further investigation on best use of adrenergic drugs, optimum dosage, and duration is warranted.

Large animal models of heart failure

Congestive heart failure (HF) is a major focus of medical research. Its incidence has greatly increased in recent decades because of an aging population base and the increasingly successful treatment of other forms of chronic cardiac disease. Relevant large animal models of HF should reflect the complex interactions of cardiac dysfunction, neurohumoral dynamics and peripheral vascular abnormalities found in human HF. A number of large animal models have been developed, especially in dogs, sheep and swine, using naturally occurring HF, or single or combinations of interventions, as instruments to trigger the development of HF. Naturally occurring HF models are not commonly used because of ethical or perceived ethical grounds, however, King Charles Cavalier Spaniel and Yucatan Mini Pig models have been described. Tachycardia induced HF is the most commonly used HF model. Ventricular pacing at 220-240 bpm results in profound low output, biventricular, oedematous failure in two to three weeks. Lower pacing rates result in a more stable, sustainable, lesser degree of failure. Positive features of this model include 'acceptance', aetiological relevance to patient tachycardia induced HF, neurohumoral and functional profile similar to most human HF, relatively low cost simple preparation, ability to manipulate the degree of failure with pacing rate, reversibility, reliability and a large amount of published multi species data. Limitations to the use of the model are the rapid onset, the fact that reversibility is only relevant to the tachycardia induced patient HF, the absence of hypertrophy in failure, the diminished plasma atrial natriuretic peptide (ANP) levels, absence of ANP of ventricular origin, and the interference between rapid pacing and therapeutic interventions. Myocardial damage models of HF include those models induced by ischaemia, eg due to coronary occlusion (ligation or aneroid) or intracoronary microembolism, transmyocardial DC shock, toxic cardiomyopathy from adriamycin, doxorubicin or catecholamines. Overload models of HF may be induced by high pressure from aortic constriction, aortic regurgitation, renal artery constriction, pulmonary stenosis or aortocaval shunts, or by induction of mitral regurgitation from chordae or leaflet damage. No single, all-encompassing, large animal model of HF exists to date. Selection of the type of model to be used should be based primarily on the hypotheses to be tested and secondarily on the available resources and facilities.

Does acute volume overloading in the setting of left ventricular dysfunction and pulmonary hypertension affect the defibrillation threshold?

The impact of acute volume overload hemodynamics on the DFT with concurrent moderate left ventricular systolic dysfunction is unknown. Ten mongrel dogs (17.2 kg), using a crossover study design, each had baseline (study 1) hemodynamic, echocardiographic, and DFT measurements. These measurements were repeated after left ventricular dysfunction was induced using a norepinephrine (5 micrograms/kg per min) infusion (study 2). Hemodynamic and DFT parameters were obtained simulating acute heart failure by volume overload with an 0.9% normal saline infusion to an associated mean pulmonary capillary wedge pressure of > 19 mmHg (study 3). Numerous significant echocardiographic and hemodynamic parameters were noted when the animals from studies 1 and 2, 2 and 3, and 1 and 3 were compared. A significant difference in the DFT was observed only when study animals 1 and 3 were compared (P < 0.02). None of the dogs were hypoxemic at the time of the acute heart failure DFT. The mechanism of this finding remains unknown. This data would suggest that acute volume overload with associated left ventricular dysfunction does adversely affect the DFT in a canine model.