The role of epinephrine, norepinephrine, and dopamine in blood pressure disturbances in patients with pheochromocytoma

Pheochromocytoma. Preoperative approach

Pheochromocytomas are rare neuroendocrine tumors that derive from the chromaffin cells of the adrenal medulla and secrete catecholamines. The measurement of plasma or fractionated urine metanephrines is the hormonal determination of choice for the biochemical diagnosis. Once the biochemical diagnosis is confirmed, the next step is the localization study. It is recommended to request a genetic study in all patients with pheochromocytomas since 40% of cases are hereditary. Once the diagnostic study is completed, preoperative treatment with alpha blockers should be instituted at least 7-14 days before adrenalectomy. However, in low-risk patients, the omission of presurgical treatment could be considered if the surgery is performed in centers with experience and a strict monitoring of the patient is carried out during the perioperative period. This document offers a practical guide on the diagnosis and perioperative approach in patients with pheochromocytomas.

Catecholamine-induced hypertensive crises: current insights and management

Phaeochromocytomas and paragangliomas (PPGLs) release catecholamines leading to catecholamine-induced hypertensive (CIH) crises, with blood pressure greater than or equal to 180/120 mm Hg. CIH crises can be complicated by tachyarrhythmias, hypotension, or life-threatening target organ damage while treatment remains undefined, often requiring co-management between endocrinologists and cardiologists. Furthermore, biochemical diagnosis of a PPGL as a cause of a CIH crisis can be difficult to identify or confounded by comorbid conditions, potentially resulting in misdiagnosis. Here, we combine relevant evidence, 60 years of collective clinical experience, insights derived from assessing over 2600 patients with PPGL, and supplementary outcomes from 100 patients (treated at the National Institutes of Health) with a CIH crisis to inform diagnosis and treatment of CIH crises. Recognising that disparities exist between availability, cost, and familiarity of various agents, flexible approaches are delineated allowing for customisation, given institutional availability and provider preference. A CIH crisis and its complications are readily treatable with available drugs, with effective intervention defining an avenue for mitigating consequent morbidity and mortality in patients with PPGL.

Metanephrine negative pheochromocytoma: a rare case report of dopamine-secreting tumor in an adolescent neurofibromatosis type 1 patient

Pheochromocytoma (PCC) occurs in 4% of pediatric neurofibromatosis type 1 (NF1) patients and is characterized by epinephrine and norepinephrine secretion. Herein, we report the first case of dopamine-secreting PCC in a 13-year-old patient with NF1. A left adrenal mass was incidentally found on abdominal computed tomography (CT ) during hypertension workup. Fractionated 24-hour urine metanephrine excretion was normal, but urine dopamine level was elevated. Focal 123I-metaiodobenzylguanidine uptake was observed on single-photon emission tomography/CT (SPECT/CT). Surgery was delayed due to small tumor size, vague symptoms, and increased dopamine level. After 6 months, focal significant uptake of the lesion on 6-[18F]fluoro-L-3,4-dihydroxyphenylalanine (18F-FDOPA) PET/CT increased and tumor size increased on abdominal CT. Laparoscopic resection was performed, and the mass was histologically confirmed as PCC. Currently, the vital signs of the patient are stable, urine dopamine level is normal, and there is no abnormal uptake of 18F-FDOPA PET/CT. This study reports a rare case of dopamine-secreting PCC. A multidisciplinary approach and focused examination are needed in metanephrine-negative, high-risk PCC patients.

Silent pheochromocytoma and paraganglioma: Systematic review and proposed definitions for standardized terminology

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors with heterogeneous clinical presentations and potential lethal outcomes. The diagnosis is based on clinical suspicion, biochemical testing, imaging and histopathological confirmation. Increasingly widespread use of imaging studies and surveillance of patients at risk of PPGL due to a hereditary background or a previous tumor is leading to the diagnosis of these tumors at an early stage. This has resulted in an increasing use of the term "silent" PPGL. This term and other variants are now commonly found in the literature without any clear or unified definition. Among the various terms, "clinically silent" is often used to describe the lack of signs and symptoms associated with catecholamine excess. Confusion arises when these and other terms are used to define the tumors according to their ability to synthesize and/or release catecholamines in relation to biochemical test results. In such cases the term "silent" and other variants are often inappropriately and misleadingly used. In the present analysis we provide an overview of the literature and propose standardized terminology in an attempt at harmonization to facilitate scientific communication.

Sporadic Noradrenergic Adrenal Pheochromocytoma in an Adolescent Patient

Pheochromocytoma and paraganglioma are neuroendocrine tumors that occur less commonly among children compared to adults. The excess catecholamines secreted by the tumor cells result in hypertension, tachycardia, excess sweating, and headache. Other symptoms include abdominal pain or distension caused by the adrenal mass. Here, we report a case of pheochromocytoma arising from the left adrenal medulla in a 14-year-old boy, which was exclusively secreting norepinephrine, as suggested by elevated plasma and 24-hour urinary norepinephrine and its metabolite normetanephrine. The epinephrine and its metabolite metanephrine were within normal limits. He presented with abdominal pain, recurrent vomiting, and headache and was noted to have elevated blood pressure. He underwent adrenalectomy after controlling his blood pressure with an alpha-blocker Prazosin. His blood pressure remained stable after surgery, and his plasma-free metanephrines returned to normal limits. He tested negative for hereditary paraganglioma-pheochromocytoma gene panel.

Risk factors for haemodynamic instability and its prolongation during laparoscopic adrenalectomy for pheochromocytoma

OBJECTIVE

Pheochromocytoma is a rare neuroendocrine tumour that secretes catecholamines and originates in the adrenal gland. Although surgical resection is the only curative therapy for pheochromocytoma, it is associated with a risk of haemodynamic instability (HDI), such as extremely high blood pressure and/or post tumour removal hypotension and shock. We investigated the risk factors for HDI during pheochromocytoma surgery.

DESIGN AND PATIENTS

Eighty-two patients who underwent laparoscopic adrenalectomy for pheochromocytoma between July 2002 and February 2020 were examined. We excluded 3 patients with bilateral disease and 11 without detailed 24 h urinary data. We defined HDI as systolic blood pressure ≥ 200 or <80 mmHg. We investigated the risk factors for HDI during laparoscopic adrenalectomy for pheochromocytoma.

RESULTS

There were 29 males and 39 females with a median age of 50.5 years. Tumours were localised on the right adrenal gland in 28 patients and on the left in 40. The median tumour diameter was 37.5 mm and the median pneumoperitoneum time was 93.5 min. Twenty-five out of sixty-eight patients (37%) developed HDI. A multivariate analysis identified diabetes mellitus (DM; odds ratio: 3.834; 95% confidence interval: 1.062-13.83; p = .04) as an independent predictor of HDI. In terms of hormonal data, median 24 h urinary epinephrine levels (p = .04) and metanephrine levels (p = .01) were significantly higher in the HDI group. DM was also considered as a risk factor for prolonged HDI (p = .02).

CONCLUSION

Surgeons and anaesthesiologists need to be aware of the risk of HDI and its prolongation during laparoscopic adrenalectomy for pheochromocytoma for DM patients.

Association between pheochromocytoma and neurofibromatosis type I: a rare entity in the African population

The association of pheochromocytoma in patients with neurofibromatosis type I has rarely been reported in low-income countries, especially on the African continent. A 43-year-old woman with neurofibromatosis type I was diagnosed with a right adrenal pheochromocytoma in Pretoria, South Africa. To our knowledge, this report is the first case to be published of a patient with neurofibromatosis type I diagnosed with a pheochromocytoma in Pretoria, and one of three cases on the African continent. The rarity may be due to the two associated conditions being under-reported, undiagnosed, misdiagnosed or possibly the association is rare on the African continent. The clinician dealing with these two conditions should be aware of the association.

Clinical profiles of patients with surgically resected pheochromocytoma and paraganglioma

BACKGROUND/AIMS

Pheochromocytoma and paraganglioma (PPGL) are catecholamine-producing tumors that can cause blood pressure (BP) elevation and cardiovascular complications. Clinical presentation of these tumors may be changed through widespread use of imaging studies, which enables detection of PPGLs before onset of symptoms. We investigated clinical profiles of patients with surgically resected PPGLs.

METHODS

From 2005 to 2017, 111 consecutive patients with surgically resected PPGLs in two tertiary hospitals in Korea were studied.

RESULTS

Mean age was 52 ± 16 years, 57 patients (51.4%) were male and 54 (48.6%) were hypertensive. Twenty-nine PPGLs (26.1%) were extra-adrenal paragangliomas. Sixteen (14.4%) and seven patients (6.3%) (Group 1, n = 23) were diagnosed during work-up of hypertension and transient cardiomyopathy respectively, and the remainder (Group 2, n = 88) were incidentalomas detected during routine abdominal imaging. Patients in the Group 1 were younger and more frequently symptomatic, and had higher BPs, heart rates and levels of urinary catecholamines than those in the Group 2. Paragangliomas were less frequent and secretion of epinephrine and metanephrine was more predominant in the Group 1 than in Group 2. After the surgical resections, 18.2% of patients still needed antihypertensive medications.

CONCLUSION

Out of 111 patients with surgically resected PPGLs, 88 (79.3%) were diagnosed as incidentalomas. Seven patients presented with transient cardiomyopathy and 16 with hypertension. Tumor location and secretion of catecholamine may vary depending on the presence of symptoms.

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.

Update of Pheochromocytoma Syndromes: Genetics, Biochemical Evaluation, and Imaging

Pheochromocytomas and paragangliomas (PCCs/PGLs) are rare commonly benign neuroendocrine tumors that share pathology features and clinical behavior in many cases. While PCCs are chromaffin-derived tumors that arise within the adrenal medulla, PGLs are neural-crest-derived tumors that originate at the extraadrenal paraganglia. Pheochromocytoma-paraganglioma (PPGL) syndromes are rapidly evolving entities in endocrinology and oncology. Discoveries over the last decade have significantly improved our understanding of the disease. These include the finding of new hereditary forms of PPGL and their associated susceptibility genes. Additionally, the availability of new functional imaging tools and advances in targeted radionuclide therapy have improved diagnostic accuracy and provided us with new therapeutic options. In this review article, we present the most recent advances in this field and provide an update of the biochemical classification that further reflects our understanding of the disease.

Clinical evaluation and treatment of phaeochromocytoma

Phaeochromocytoma and extra adrenal paraganglioma are rare neuroendocrine tumours and have the potential to secrete adrenaline, noradrenaline and dopamine causing a myriad of clinical symptoms. Prompt diagnosis is essential for clinicians and requires a multidisciplinary specialist approach for the clinical and laboratory investigation, diagnosis, treatment and follow-up of patients. This paper is an integrated review of the clinical and laboratory evaluation and treatment of patients suspected to have phaeochromocytoma or paraganglioma, highlighting recent developments and best practices from recent published clinical guidelines.

PRECISION MEDICINE: AN UPDATE ON GENOTYPE/BIOCHEMICAL PHENOTYPE RELATIONSHIPS IN PHEOCHROMOCYTOMA/PARAGANGLIOMA PATIENTS

OBJECTIVE

Pheochromocytomas and paragangliomas (PPGLs) are rare neuroendocrine tumors known to produce and secrete high levels of circulating catecholamines and their metabolites. The biochemical characteristics of these tumors can be used to divide them into three major phenotypes. The adrenergic, noradrenergic and dopaminergic phenotypes are defined by predominant elevations in epinephrine and metanephrine, norepinephrine and normetanephrine, and dopamine and 3-methoxytyramine, respectively. There are over 15 well-identified tumor-susceptibility genes responsible for approximately 40% of the cases. The objective of this review article is to outline specific genotype/biochemical phenotype relationships.

METHODS

Literature review.

RESULTS

None.

CONCLUSION

Biochemical phenotype of PPGL is determined by the underlying genetic mutation and the associated molecular pathway. Identification of genotype/biochemical relationships is valuable in prioritizing testing for specific genes, making treatment decisions and monitoring disease progression.

ABBREVIATIONS

3-MT = 3-methoxytyramine; EPAS1 = endothelial pas domain protein 1; FH = fumarate hydratase; HIF2A = hypoxia inducible factor type 2A; MEN2 = multiple endocrine neoplasia type 2; NF1 = neurofibromatosis type 1; PNMT = phenylethanolamine N-methyltransferase; PPGL = pheochromocytoma and paraganglioma; RET = rearranged during transfection; SDH = succinate dehydrogenase; SDHAF2 = succinate dehydrogenase complex assembly factor 2; TCA = tricarboxylic acid; TH = tyrosine hydroxylase; TMEM127 = transmembrane protein 127; VHL = von Hippel-Lindau.

A Rare Case of Adrenal Pheochromocytoma with Unusual Clinical and Biochemical Presentation: A Case Report and Literature Review

A 50-year-old Omani woman presented to the Outpatient Clinic, Royal Hospital, Oman with right upper abdominal pain and backache that had lasted 10 days. She had no palpitation, sweating, or hypertension (blood pressure 122/78mmHg). The patient's history revealed that she had a similar incidence of abdominal pain two months prior, which was a "dull ache" in nature and somewhat associated with headache. The pain was relieved using a mild analgesic drug. Abdominal ultrasonography showed a right adrenal mass, and both computed tomography and magnetic resonance imaging of the adrenal glands confirmed a right adrenal mass consistent with adrenal pheochromocytoma. However, clinical biochemistry tests revealed normal levels of plasma catecholamines (dopamine, norepinephrine, and epinephrine) and metanephrine, which are unusual findings in adrenal pheochromocytoma. Meanwhile, the patient had markedly raised plasma normetanephrine (10-fold) which, together with the normal metanephrine, constitutes a metabolic profile that is compatible with extra-adrenal pheochromocytoma. The patient also had markedly raised chromogranin A (16-fold), consistent with the presence of a neuroendocrine tumor. Laparoscopic right adrenalectomy was done and the adrenal tumor was excised and retrieved in total. Histopathology and immunohistochemistry confirmed the diagnosis of adrenal pheochromocytoma; the tumor cells being positive for chromogranin, synaptophysin, and S-100 protein. Following surgery, the patient did well and showed full recovery at follow-up after three months. Molecular genetic testing showed no pathogenic mutation in pheochromocytoma genes: MAX, SDHA, SDHAF2, SDHB, SDHC, SDHD, VHL, and PRKAR1A. A review of the literature was conducted to identify the pathophysiology and any previous reports of such case. To our knowledge, this is the first report in Oman of the extremely rare entity of pheochromocytoma with an unusual clinical and biochemical scenario.

Norepinephrine deficiency with normal blood pressure control in congenital insensitivity to pain with anhidrosis

OBJECTIVE

Congenital insensitivity to pain with anhidrosis (CIPA) is caused by mutations in the NKTR1 gene. This affects the development of nerve growth factor (NGF)-dependent neurons including sympathetic cholinergic neurons in the skin, causing anhidrosis. Cardiovascular and blood pressure regulation appears normal, but the integrity of sympathetic adrenergic neurons has not been tested.

METHODS

We examined the effect of posture on blood pressure, heart rate, plasma concentration of catecholamines, vasopressin, endothelin, and renin activity in 14 patients with CIPA, 10 patients with chronically deficient sympathetic activity (pure autonomic failure), and 15 normal age-matched controls.

RESULTS

In all 14 patients with CIPA, plasma norepinephrine levels were very low or undetectable and failed to increase when the patient was upright, yet upright blood pressure was well maintained. Plasma epinephrine levels were normal and increased when the patient was upright. Plasma renin activity also increased appropriately when the patient was upright and after furosemide-induced volume depletion. Nitric oxide-mediated endothelial function was intact. Patients with pure autonomic failure also had very low levels of plasma norepinephrine both supine and upright, but in contrast to patients with CIPA failed to maintain blood pressure upright.

INTERPRETATION

The results indicate that postganglionic sympathetic neurons are severely depleted in CIPA, but chromaffin cells of the adrenal medulla are spared. This confirms the differential effect of NGF signaling for sympathetic neural and chromaffin cell development. The finding that patients with CIPA maintain blood pressure well on standing challenges current concepts of the role of norepinephrine in the regulation of arterial pressure.

Hypertensive crisis caused by electrocauterization of the adrenal gland during hepatectomy

BACKGROUND

Hypertensive crisis (i.e., systolic blood pressure over 300 mmHg) is very rare during operation except pheochromocytoma, but it can be a fatal and embarrassing to surgeons and anesthesiologists. The right adrenal gland can be electrocauterized during a right hemi-hepatectomy. We report a case of hypertensive crisis during right hemi-hepatectomy in which the right adrenal gland was stimulated by monopolar electrocautery in a patient with normal neuroendocrine function.

CASE PRESENTATION

A 73-year-old man with hepatocellular carcinoma was scheduled to undergo right hemi-hepatectomy. Three hours into the surgery, the patient's blood pressure increased abruptly from 100/40 to over 350/130 mmHg (the maximum measurement pressure of the monitor; 350 mmHg). The surgeon had cauterized the right adrenal gland using monopolar electrocautery to separate the liver from the adrenal gland immediately prior to the event. Approximately 3 minutes after suspending the operation, blood pressure returned to baseline levels. After the event, the operation was successfully completed without any complication. Hormonal studies and iodine-123 meta-iodobenzylguanidine scintigraphy revealed no neuroendocrine tumor such as a pheochromocytoma.

CONCLUSION

Operations such as hepatectomy that stimulate the adrenal gland may lead to an unexpected catecholamine surge and result in hypertensive crisis, even if neuroendocrine function of the adrenal gland is normal.

Pathophysiology and diagnosis of disorders of the adrenal medulla: focus on pheochromocytoma

The principal function of the adrenal medulla is the production and secretion of catecholamines. During stressful challenging conditions, catecholamines exert a pivotal homeostatic role. Although the main adrenomedullary catecholamine, epinephrine, has a wide array of adrenoreceptor-mediated effects, its absence does not cause life-threatening problems. In contrast, excess production of catecholamines due to an adrenomedullary tumor, specifically pheochromocytoma, results in significant morbidity and mortality. Despite being rare, pheochromocytoma has a notoriously bad reputation because of its potential devastating effects if undetected and untreated. The paroxysmal signs and symptoms and the risks of missing or delaying the diagnosis are well known for most physicians. Nevertheless, even today the diagnosis is still overlooked in a considerable number of patients. Prevention and complete cure are however possible by early diagnosis and appropriate treatment but these patients remain a challenge for physicians. Yet, biochemical proof of presence or absence of catecholamine excess has become more easy and straightforward due to developments in assay methodology. This also applies to radiological and functional imaging techniques for locating the tumor. The importance of genetic testing for underlying germline mutations in susceptibility genes for patients and relatives is increasingly recognized. Yet, the effectiveness of genetic testing, in terms of costs and benefits to health, has not been definitively established. Further improvement in knowledge of genotype-phenotype relationships in pheochromocytoma will open new avenues to a more rationalized and personalized diagnostic approach of affected patients.

Anesthetic management of a pregnant woman undergoing laparoscopic surgery for pheochromocytoma -A case report-

Pheochromocytoma is a rare catecholamine producing tumor. Anesthetic management for the resection of pheochromocytoma is hard and challenging issue to anesthesiologist, because of its potentially lethal cardiovascular complications. It becomes more complicated when the patient is pregnant. Clinicians must keep the safety of both mother and fetus in mind. The timing of surgery for pheochromocytoma in pregnancy is very important for the maternal and fetal safety and depends on the gestational age when diagnosis is made, clinical response to medical treatment, the surgical accessibility of the tumor, and the presence of fetal distress. We report anesthetic experience of a laparoscopic resection for pheochromocytoma in 25th week gestational woman.

Hypertension in pheochromocytoma: characteristics and treatment

Pheochromocytoma is a tumor of the chromaffin cells in the adrenal medulla and sympathetic paraganglia, which synthesizes and secretes catecholamines. Norepinephrine, epinephrine, and dopamine all act on their target receptors, which causes a physiologic change in the body. High circulating levels of catecholamines can lead to severe hypertension and can have devastating effects on multiple body systems (eg, cardiovascular, cerebrovascular), and can lead to death if untreated. Although surgical treatment represents the only modality of ultimate cure, pharmacologic preoperative treatment remains the mainstay of successful outcome.

Catecholamine metabolomic and secretory phenotypes in phaeochromocytoma

Phaeochromocytomas and paragangliomas (PPGLs) are highly heterogeneous tumours with variable catecholamine biochemical phenotypes and diverse hereditary backgrounds. This analysis of 18 catecholamine-related plasma and urinary biomarkers in 365 patients with PPGLs and 846 subjects without PPGLs examined how catecholamine metabolomic profiles are impacted by hereditary background and relate to variable hormone secretion. Catecholamine secretion was assessed in a subgroup of 156 patients from whom tumour tissue was available for measurements of catecholamine contents. Among all analytes, the free catecholamine O-methylated metabolites measured in plasma showed the largest tumour-related increases relative to the reference group. Patients with tumours due to multiple endocrine neoplasia type 2 and neurofibromatosis type 1 (NF1) showed similar catecholamine metabolite and secretory profiles to patients with adrenaline-producing tumours and no evident hereditary background. Tumours from these three patient groups contained higher contents of catecholamines, but secreted the hormones at lower rates than tumours that did not contain appreciable adrenaline, the latter including PPGLs due to von Hippel-Lindau (VHL) and succinate dehydrogenase (SDH) gene mutations. Large increases of plasma dopamine and its metabolites additionally characterised patients with PPGLs due to the latter mutations, whereas patients with NF1 were characterised by large increases in plasma dihydroxyphenylglycol and dihydroxyphenylacetic acid, the deaminated metabolites of noradrenaline and dopamine. This analysis establishes the utility of comprehensive catecholamine metabolite profiling for characterising the distinct and highly diverse catecholamine metabolomic and secretory phenotypes among different groups of patients with PPGLs. The data further suggest developmental origins of PPGLs from different populations of chromaffin cell progenitors.

Cerebral infarction along the distribution of perforating arteries during aneurysm surgery in a patient with pheochromocytoma--case report

A 58-year-old woman with refractory hypertension presented with subarachnoid hemorrhage. Digital subtraction angiography and three-dimensional computed tomography (CT) angiography revealed a ruptured left vertebral artery (VA) aneurysm and an unruptured left middle cerebral artery (MCA) aneurysm. The patient successfully underwent neck clipping of the left VA aneurysm. However, CT obtained just after the operation showed an asymptomatic cerebral infarction along the distribution of medial striate arteries of the right anterior cerebral artery in the caudate nucleus. The pathogenesis of the infarction was unknown. Before clipping surgery of the left MCA aneurysm, detailed examinations to find the cause of her refractory hypertension were performed. Laboratory tests revealed plasma serum level of norepinephrine at 15,521 pg/ml (normal range 100-450 pg/ml). Abdominal magnetic resonance imaging revealed a pheochromocytoma in the right adrenal gland. After preoperative management of the pheochromocytoma, the neck of the left MCA aneurysm was successfully clipped. When the patient awakened from anesthesia, she noticed right hemiparesis and motor aphasia. CT showed cerebral infarction along the distribution of lenticulostriate arteries of the left MCA in the putamen. Her symptoms gradually improved, and the pheochromocytoma was removed by laparoscopic surgery. Sustained severe hypertension and depletion of blood volume resulting from excess catecholamine release from the pheochromocytoma may have caused the complications. Hypervolemic fluid infusion and maintenance of normotensive blood pressure during surgery may avoid such ischemic events.

Non-invasive estimation of systolic blood pressure and diastolic blood pressure using photoplethysmograph components

PURPOSE

Photoplethysmography (PPG) is a noninvasive optical technology that detects changes in blood volume in the vascular system. This study aimed to investigate the possibilities of monitoring the cardiovascular system status by using PPG.

MATERIALS AND METHODS

Forced hemodynamic changes were induced using cardiac stimulants; dopamine and epinephrine, and PPG components were recorded by a noninvasive method at the peripheral blood vessels. The results were compared among 6 dogs. Endotracheal intubation was performed after an intramuscular injection of 25 mg/kg ketamine sulfate, and anesthesia was maintained with 2% enflurane. After stabilizing the animals for 15 min, 16 mg/mL diluted dopamine was injected into a vein for 2 min at 20 microg/kg min(-1) by using an infusion pump. Thereafter, the infusion pump was stopped, and 1 mg epinephrine was injected intravenously. Fluid administration was controlled to minimize preload change in blood pressure.

RESULTS

After stimulant administration, systolic blood pressure (SBP) and diastolic blood pressures (DBP) increased. The direct current (DC) component, which reflects changes in blood volume, decreased while the alternating current (AC) component, which reflects changes in vascular compliance and resistance, increased. The correlation coefficient between SBP and the foot of the DC component was 0.939 (p < 0.01), while it was 0.942 (p < 0.01) for DBP and the peak of the DC component. The AC component could predict the increase in vascular resistance from a stable pulse blood volume, even with increased pulse pressure.

CONCLUSION

These results support the possibility that PPG components may be used for easy and noninvasive measurement of hemodynamic changes in the cardiovascular system.

Clinical spectrum of pheochromocytoma

BACKGROUND

Pheochromocytomas vary in presentation, tumor size, and in catecholamine production. Whether pheochromocytoma size correlates with hormone levels, clinical presentation, and perioperative complications is not known. The goal of this study was to determine if tumor size and hormone level correlate according to the clinical presentation at diagnosis.

STUDY DESIGN

We retrospectively analyzed all patients who underwent an adrenalectomy with a diagnosis of a pheochromocytoma from February 1996 to October 2008. We grouped patients according to their clinical presentation at diagnosis (routine biochemical screening, incidentaloma, classic symptoms, pheochromocytoma crisis) and obtained preoperative radiographic tumor size and catecholamine hormone levels. ANOVA was used for the group effects and the Kruskal-Wallis rank test was used for pairwise comparison between groups with the Sidak/Bonferroni method for multiplicity adjustment according to age, tumor size, and hormone level. The Pearson correlation coefficient was then calculated to determine if hormone level correlated with tumor size.

RESULTS

Eighty-one of 107 patients had data available for complete analysis. The average age at diagnosis for all patients was 47.1 years, and the average tumor size was 4.9 cm. The average highest hormone ratio among all patients was 27.4. Tumor size and hormone ratio levels differed among all groups (p < or = 0.03). A direct correlation (p = 0.014) was apparent between tumor size and hormone level. Complication rates also differed among the four groups of patients (p < or = 0.02).

CONCLUSIONS

Our study showed that tumor size directly correlates with hormone level. Smaller tumors tend to secrete lower levels of catecholamines, but larger tumors have a wider variation in secretory potential. Larger tumors, however, produced the highest hormone ratios.

Differential expression of the regulated catecholamine secretory pathway in different hereditary forms of pheochromocytoma

Pheochromocytomas in patients with von Hippel-Lindau (VHL) syndrome and multiple endocrine neoplasia type 2 (MEN 2) differ in the types and amounts of catecholamines produced and the resulting signs and symptoms. We hypothesized the presence of different processes of catecholamine release reflecting differential expression of components of the regulated secretory pathway among the two types of hereditary tumors. Differences in catecholamine secretion from tumors in patients with VHL syndrome (n = 47) and MEN 2 (n = 32) were examined using measurements of catecholamines in tumor tissue, urine, and plasma, the last of which was under baseline conditions in all subjects and in a subgroup of patients who received intravenous glucagon to provoke catecholamine release. Microarray and proteomics analyses, quantitative PCR, and Western blotting were used to assess expression of tumor tissue secretory pathway components. The rate constant for baseline catecholamine secretion was 20-fold higher in VHL than in MEN 2 tumors (0.359 +/- 0.094 vs. 0.018 +/- 0.009 day(-1)), but catecholamine release was responsive only to glucagon in MEN 2 tumors. Compared with tumors from MEN 2 patients, those from VHL patients were characterized by reduced expression of numerous components of the regulated secretory pathway (e.g., SNAP25, syntaxin, rabphilin 3A, annexin A7, calcium-dependent secretion activator). The mutation-dependent differences in expression of secretory pathway components indicate a more mature regulated secretory pathway in MEN 2 than VHL tumors. These data provide a unique mechanistic link to explain how variations in the molecular machinery governing exocytosis may contribute to clinical differences in the secretion of neurotransmitters or hormones and the subsequent presentation of a disease.

Resistant hypertension: diagnosis, evaluation, and treatment: a scientific statement from the American Heart Association Professional Education Committee of the Council for High Blood Pressure Research

Resistant hypertension is a common clinical problem faced by both primary care clinicians and specialists. While the exact prevalence of resistant hypertension is unknown, clinical trials suggest that it is not rare, involving perhaps 20% to 30% of study participants. As older age and obesity are 2 of the strongest risk factors for uncontrolled hypertension, the incidence of resistant hypertension will likely increase as the population becomes more elderly and heavier. The prognosis of resistant hypertension is unknown, but cardiovascular risk is undoubtedly increased as patients often have a history of long-standing, severe hypertension complicated by multiple other cardiovascular risk factors such as obesity, sleep apnea, diabetes, and chronic kidney disease. The diagnosis of resistant hypertension requires use of good blood pressure technique to confirm persistently elevated blood pressure levels. Pseudoresistance, including lack of blood pressure control secondary to poor medication adherence or white coat hypertension, must be excluded. Resistant hypertension is almost always multifactorial in etiology. Successful treatment requires identification and reversal of lifestyle factors contributing to treatment resistance; diagnosis and appropriate treatment of secondary causes of hypertension; and use of effective multidrug regimens. As a subgroup, patients with resistant hypertension have not been widely studied. Observational assessments have allowed for identification of demographic and lifestyle characteristics associated with resistant hypertension, and the role of secondary causes of hypertension in promoting treatment resistance is well documented; however, identification of broader mechanisms of treatment resistance is lacking. In particular, attempts to elucidate potential genetic causes of resistant hypertension have been limited. Recommendations for the pharmacological treatment of resistant hypertension remain largely empiric due to the lack of systematic assessments of 3 or 4 drug combinations. Studies of resistant hypertension are limited by the high cardiovascular risk of patients within this subgroup, which generally precludes safe withdrawal of medications; the presence of multiple disease processes (eg, sleep apnea, diabetes, chronic kidney disease, atherosclerotic disease) and their associated medical therapies, which confound interpretation of study results; and the difficulty in enrolling large numbers of study participants. Expanding our understanding of the causes of resistant hypertension and thereby potentially allowing for more effective prevention and/or treatment will be essential to improve the long-term clinical management of this disorder.

Gender-related differences in the clinical presentation of malignant and benign pheochromocytoma

Signs and symptoms associated with pheochromocytomas are predominantly caused by catecholamine excess, but tend to be highly variable and non-specific. In this study, we evaluated 23 male and 35 female pheochromocytoma patients for symptoms and signs of pheochromocytoma with special regard to gender-related differences in presentation. Total symptom score comparison between genders showed significant differences (12.0 vs. 7.8, P-value 0.0001). Female patients reported significantly more headache (80% vs. 52%), dizziness (83% vs. 39%), anxiety (85% vs. 50%), tremor (64% vs. 33%), weight change (88% vs. 43%), numbness (57% vs. 24%), and changes in energy level (89% vs. 64%). Females and males displayed comparable biochemical phenotypes (60% and 65% noradrenergic phenotype, respectively). Use of alpha- and/or beta-blockade between males and females did not differ significantly. Subgroup analyses and multiple regression analysis revealed gender differences to be irrespective of benign or malignant disease, use of adrenoceptor-blockade, age and biochemical phenotype. We conclude female patients have significantly more self-reported pheochromocytoma signs and symptoms than male patients irrespective of biochemical phenotype and tumor presentation which may be related to distinct catecholamine receptor sensitivity. Clinicians should be aware of these complaints in female pheochromocytoma patients and offer adequate treatment if indicated.

Resistant hypertension: diagnosis, evaluation, and treatment. A scientific statement from the American Heart Association Professional Education Committee of the Council for High Blood Pressure Research

Resistant hypertension is a common clinical problem faced by both primary care clinicians and specialists. While the exact prevalence of resistant hypertension is unknown, clinical trials suggest that it is not rare, involving perhaps 20% to 30% of study participants. As older age and obesity are 2 of the strongest risk factors for uncontrolled hypertension, the incidence of resistant hypertension will likely increase as the population becomes more elderly and heavier. The prognosis of resistant hypertension is unknown, but cardiovascular risk is undoubtedly increased as patients often have a history of long-standing, severe hypertension complicated by multiple other cardiovascular risk factors such as obesity, sleep apnea, diabetes, and chronic kidney disease. The diagnosis of resistant hypertension requires use of good blood pressure technique to confirm persistently elevated blood pressure levels. Pseudoresistance, including lack of blood pressure control secondary to poor medication adherence or white coat hypertension, must be excluded. Resistant hypertension is almost always multifactorial in etiology. Successful treatment requires identification and reversal of lifestyle factors contributing to treatment resistance; diagnosis and appropriate treatment of secondary causes of hypertension; and use of effective multidrug regimens. As a subgroup, patients with resistant hypertension have not been widely studied. Observational assessments have allowed for identification of demographic and lifestyle characteristics associated with resistant hypertension, and the role of secondary causes of hypertension in promoting treatment resistance is well documented; however, identification of broader mechanisms of treatment resistance is lacking. In particular, attempts to elucidate potential genetic causes of resistant hypertension have been limited. Recommendations for the pharmacological treatment of resistant hypertension remain largely empiric due to the lack of systematic assessments of 3 or 4 drug combinations. Studies of resistant hypertension are limited by the high cardiovascular risk of patients within this subgroup, which generally precludes safe withdrawal of medications; the presence of multiple disease processes (eg, sleep apnea, diabetes, chronic kidney disease, atherosclerotic disease) and their associated medical therapies, which confound interpretation of study results; and the difficulty in enrolling large numbers of study participants. Expanding our understanding of the causes of resistant hypertension and thereby potentially allowing for more effective prevention and/or treatment will be essential to improve the long-term clinical management of this disorder.

Adverse drug reactions in patients with phaeochromocytoma: incidence, prevention and management

The dangers of phaeochromocytomas are mainly due to the capability of these neuroendocrine tumours to secrete large quantities of vasoactive catecholamines, thereby increasing blood pressure and causing other related adverse events or complications. Phaeochromocytomas are often missed, sometimes only becoming apparent during therapeutic interventions that provoke release or interfere with the disposition of catecholamines produced by the tumours. Because phaeochromocytomas are rare, evidence contraindicating use of specific drugs is largely anecdotal or based on case reports. The heterogeneous nature of the tumours also makes adverse reactions highly variable among patients. Some drugs, such as dopamine D(2) receptor antagonists (e.g. metoclopramide, veralipride) and beta-adrenergic receptor antagonists (beta-blockers) clearly carry high potential for adverse reactions, while others such as tricyclic antidepressants seem more inconsistent in producing complications. Other drugs capable of causing adverse reactions include monoamine oxidase inhibitors, sympathomimetics (e.g. ephedrine) and certain peptide and corticosteroid hormones (e.g. corticotropin, glucagon and glucocorticoids). Risks associated with contraindicated medications are easily minimised by adoption of appropriate safeguards (e.g. adrenoceptor blockade). Without such precautions, the state of cardiovascular vulnerability makes some drugs and manipulations employed during surgical anaesthesia particularly dangerous. Problems arise most often when drugs or therapeutic procedures are employed in patients in whom the tumour is not suspected. In such cases, it is extremely important for the clinician to recognise the possibility of an underlying catecholamine-producing tumour and to take the most appropriate steps to manage and treat adverse events and clinical complications.

Preoperative management of the pheochromocytoma patient

Pheochromocytomas are rare neuroendocrine tumors with a highly variable clinical presentation, but they most commonly present as spells of headaches, sweating, palpitations, and hypertension. Patients with pheochromocytoma may develop complicated and potentially lethal cardiovascular and other complications, especially in the setting of diagnostic or interventional procedures (e.g. upon induction of anesthesia or during surgery). The serious and potentially lethal nature of such complications is due to the potent effect of paroxysmal release of catecholamines. Because this warrants prompt diagnosis and treatment, the physician should be aware of the clinical manifestations and complications of catecholamine excess and be able to provide proper preoperative management to minimize catecholamine-related pre-, intra-, and postoperative adverse events. The following clinical scenario and discussion aim to enhance the knowledge of the physician regarding the behavior of pheochromocytoma and to outline current approaches to comprehensive preoperative management of patients suffering from this tumor.

Pheochromocytoma as a catecholamine producing tumor: implications for clinical practice

Pheochromocytomas are catecholamine-producing tumors presenting with various clinical symptoms, but mostly with headache, sweating, palpitations and hypertension. If not properly diagnosed, secretion of catecholamines may lead to fatal cardiovascular consequences. Biochemical testing for pheochromocytoma should be performed not only in symptomatic subjects or in subjects with adrenal incidentaloma but also in subjects with a genetic predisposition for pheochromocytoma (multiple endocrine neoplasia type 2, Von Hippel-Lindau (VHL) syndrome, neurofibromatosis type 1 (NF 1)and mutations of succinate dehydrogenase (SDH) genes). Once a pheochromocytoma is proven, computed tomography (CT), magnetic resonance imaging (MRI) and functional imaging with [(123)I]-MIBG may be used for tumor localization. Adequate medical pre-treatment is essential for successful operation which is performed in most cases by laparoscopy. After tumor removal, further follow-up is necessary due to possible recurrence. Although prognosis after tumor resection is excellent, a significant proportion of pheochromocytomas recur, some as metastases. Thus, appropriate follow-up is mandatory.

Epinephrine-secreting pheochromocytoma in a normotensive woman with adrenal incidentaloma

Pheochromocytomas are rare neuroendocrine tumors that produce, metabolize, and usually secrete catecholamines. Although hypertension is a common presenting feature of pheochromocytoma, the tumors occur (or are present) in only 0.1% of patients with hypertension. The variability of symptoms and rarity of occurrence render these tumors difficult to diagnose; many are discovered incidentally during radiological examination or at autopsy. A patient is presented with a pheochromocytoma that was discovered incidentally when she presented with abdominal pain and a normal blood pressure.

Characteristics of Blood Pressure in Pheochromocytoma

Pheochromocytomas are catecholamine-producing tumors arising from chromaffin cells. One of the most typical symptoms of the catecholamine-excess state is hypertension either in the sustained or paroxysmal form, and its severity does not depend on the level of circulating catecholamines. On the other hand, hypertension in pheochromocytoma is very often characterized by the amelioration or even inversion of the circadian blood pressure rhythm. In some subjects, high circulating levels of catecholamines lead to the enhanced blood pressure variability. One possible explanation for such blood pressure variability is the desensitization of the catecholamine receptors due to high levels of circulating catecholamines.

Increased blood pressure variability in pheochromocytoma compared to essential hypertension patients

OBJECTIVE

Catecholamines are responsible for short and long-lasting blood pressure (BP) elevations in pheochromocytoma. We investigated whether in patients with pheochromocytoma this catecholamine excess would result in higher BP variability in comparison with patients suffering from essential hypertension (EH).

DESIGN

We examined retrospectively 54 (26 treated with alpha1-blockers) patients with pheochromocytoma (30 patients also investigated after tumour removal) and 108 (42 treated with alpha1-blockers) patients with EH. They all underwent 24-h ambulatory BP monitoring. To assess the BP variability, coefficient of BP variability (SD of average BP/average BP) was used.

RESULTS

In subjects with pheochromocytoma, a higher coefficient of BP variability was shown compared with EH during the 24-h period (0.12 +/- 0.03 versus 0.10 +/- 0.02, P = 0.003 for systolic BP in the treated group) and mainly during the daytime (0.11/0.13 +/- 0.04/0.03 versus 0.09/0.11 +/- 0.03/0.04, P = 0.007/0.06 for systolic/diastolic BP in the untreated group and 0.12/0.13 +/- 0.04/0.04 versus 0.09/0.12 +/- 0.04/0.02, P < 0.001/0.01 in the treated group). Tumour removal resulted in a decrease of the previously increased 24-h (0.11 +/- 0.03 versus 0.10 +/- 0.03, P = 0.04) and daytime (0.11 +/- 0.03 versus 0.09 +/- 0.03, P = 0.03) coefficient of systolic BP variation. Twenty-seven subjects with pheochromocytoma and inverted circadian BP rhythm (night-time BP > daytime BP) had a significantly higher 24-h (0.13 +/- 0.03 versus 0.10 +/- 0.03, P < 0.001 for systolic BP) and daytime coefficient of BP variation (0.13/0.15 +/- 0.04/0.03 versus 0.09/0.12 +/- 0.02/0.02, P < 0.001/<0.001) and also a higher occurrence of the isolated excretion of norepinephrine (14 versus seven subjects, P = 0.05) compared with the 27 subjects with pheochromocytoma without inverted circadian BP rhythm.

CONCLUSION

The excess of catecholamines in patients with pheochromocytoma is associated with higher long-term BP variability in comparison with patients suffering from EH especially in subjects with inverted circadian BP rhythm. Tumour removal resulted in the amelioration of the previously increased BP variability.

Dopamine-secreting pheochromocytomas: in search of a syndrome

Pheochromocytomas rarely produce dopamine as the only catecholamine. Two cases are reported here, and a review of the literature was conducted. Unlike norepinephrine-and epinephrine-secreting tumors, dopamine-secreting pheochromocytomas lack a classic clinical presentation and are often asymptomatic. Urinary and serum metabolites cannot be relied on to make the diagnosis, and serum or urine dopamine levels (or both) must be measured when dealing with a potential pheochromocytoma. Dopamine-secreting tumors are less likely to enhance with metaiodobenzylguanidine (MIBG) scanning and may benefit from the use of positron emission tomography. Treatment is en bloc surgical excision; but unlike other pheochromocytomas, alpha-blockade is not indicated as it may lead to hypotension and cardiovascular collapse. Metyrosine is a medication that can be useful for preoperative control of symptoms from these tumors. The function of metyrosine is to block dopamine synthesis; it has no alpha-blocking effect. This medication is an option for controlling symptoms but should not be used routinely in these patients. The prognosis for patients with these tumors is worse than for those with an epinephrine- and norepinephrine-secreting tumor. Because of their asymptomatic nature, dopamine-secreting pheochromocytomas tend to be detected later and are more likely to be malignant at the time of diagnosis.

Pheochromocytoma catecholamine phenotypes and prediction of tumor size and location by use of plasma free metanephrines

BACKGROUND

Measurements of plasma free metanephrines (normetanephrine and metanephrine) provide a useful test for diagnosis of pheochromocytoma and may provide other information about the nature of these tumors.

METHODS

We examined relationships of tumor size, location, and catecholamine content with plasma and urinary metanephrines or catecholamines in 275 patients with pheochromocytoma. We then prospectively examined whether measurements of plasma free metanephrines could predict tumor size and location in an additional 16 patients.

RESULTS

Relative proportions of epinephrine and norepinephrine in tumor tissue were closely matched by relative increases of plasma or urinary metanephrine and normetanephrine, but not by epinephrine and norepinephrine. Tumor diameter showed strong positive relationships with summed plasma concentrations or urinary outputs of metanephrine and normetanephrine (r = 0.81 and 0.77; P <0.001), whereas relationships with plasma or urinary catecholamines were weaker (r = 0.41 and 0.44). All tumors in which increases in plasma metanephrine were >15% of the combined increases of normetanephrine and metanephrine either had adrenal locations or appeared to be recurrences of previously resected adrenal tumors. Measurements of plasma free metanephrines predicted tumor diameter to within a mean of 30% of actual diameter, and high plasma concentrations of free metanephrine relative to normetanephrine accurately predicted adrenal locations.

CONCLUSIONS

Measurements of plasma free metanephrines not only provide information about the likely presence or absence of a pheochromocytoma, but when a tumor is present, can also help predict tumor size and location. This additional information may be useful for clinical decision-making during tumor localization procedures.

Clinical and biochemical features of sporadic and hereditary phaeochromocytomas: an analysis of 41 cases investigated in a single endocrine centre

The aims of this study were to estimate the prevalence of phaeochromocytomas among adrenal tumours and to analyse the clinical and biochemical features of sporadic and hereditary tumours. Our series of 609 adrenal tumours evaluated between January 1995 and July 2003 was reviewed. Catecholamine content in phaeochromocytoma tissues was also determined and correlated with clinical behaviour and biochemical parameters of patients. Forty-one (6.7%) of the 609 patients had phaeochromocytomas, of which 28 were sporadic (25 benign and three malignant) and 13 (all benign) were associated with hereditary diseases (multiple endocrine neoplasia type 2A in seven cases from four unrelated families carrying mutations of the RET gene, von Hippel-Lindau disease in two unrelated cases with mutations of the VHL gene, and type 1 neurofibromatosis in four unrelated cases). Bilateral tumours were found in three patients with hereditary syndromes and in one sporadic case. Tumour diameter was slightly but not significantly greater in patients with hereditary than in those with sporadic tumours. Systolic but not diastolic blood pressure was significantly higher in patients with sporadic compared with those with hereditary tumours, but comparison of other clinical data and biochemical parameters indicated an absence of significant differences in the mean age, presenting symptoms, heart rate, or fasting serum glucose levels. Tissue catecholamine content measured in 8 sporadic and 5 hereditary phaeochromocytomas was highly variable and it failed to show significant differences between hereditary and sporadic tumours. These results indicate a high proportion of hereditary diseases among patients with phaeochromocytomas. Genetic and clinical testing for hereditary diseases may be of great help to offer an appropriate treatment, follow-up and family screening for these patients.

Surgical management of pheochromocytoma

The early diagnosis and safe treatment of pheochromocytoma have become possible due to advances in preoperative imaging techniques and endocrine tests, as well as improvements in the control of blood pressure and hemodynamics before and during the operation using various drugs. This article outlines the use of meticulous surgical technique via various approaches for open surgery and gives a step-by-step description of the methods for laparoscopic surgery. Such techniques have made the excision of pheochromocytoma safe and easy, allowing hypertension to be surgically cured in these patients. Thus, pheochromocytoma is less likely to be fatal than before. However. it is necessary to follow these patients for a long period postoperatively because it is often difficult to distinguish benign from malignant tumors and recurrence has been reported even more than ten years postoperatively.