Current progress in clinical, molecular, and genetic aspects of adult fibromuscular dysplasia

Evidence for routine brain-to-pelvis imaging and antiplatelet therapy in patients diagnosed with fibromuscular dysplasia

Fibromuscular dysplasia (FMD) is a disease of the musculature of arterial walls leading to stenoses, aneurysms, and dissections. The purpose of this report was to summarize the evidence for (1) one-time routine imaging from brain-to-pelvis and (2) lifelong antiplatelet therapy, for example, aspirin, for patients diagnosed with FMD as suggested by an international consensus report from 2019. PubMed was systematically searched, and the evidence providing a basis for the current consensus points, as well as articles published since, were reviewed. In four registries evaluating patients with FMD, the prevalence of multivessel involvement, aneurysms, and dissections was reported to be 43.5%-66.3%, 21.6%-30.6%, and 5.6%-28.1%, respectively. Any antiplatelet drug was used in 72.9% of patients, and aspirin was prescribed in up to 70.2% of patients. Based on the high prevalence of vascular manifestations, their associated morbidity, and the potential for endovascular or surgical intervention, the suggestion of one-time brain-to-pelvis screening with computed tomography angiography or magnetic resonance angiography is well supported. Contrarily, the evidence to support the consensus statement of lifelong antiplatelet therapy to all patients in the absence of contraindications is more uncertain since a beneficial effect has not been demonstrated specifically in patients with fibromuscular dysplasia. Therefore, until the efficacy and safety of primary thromboprophylaxis have been demonstrated in this patient group specifically, it may be equally appropriate to only use antiplatelet agents in patients with a clear indication after individual evaluation according to risk factors for thrombotic and thromboembolic complications.

Vascular remodelling in cardiovascular diseases: hypertension, oxidation, and inflammation

Optimal vascular structure and function are essential for maintaining the physiological functions of the cardiovascular system. Vascular remodelling involves changes in vessel structure, including its size, shape, cellular and molecular composition. These changes result from multiple risk factors and may be compensatory adaptations to sustain blood vessel function. They occur in diverse cardiovascular pathologies, from hypertension to heart failure and atherosclerosis. Dynamic changes in the endothelium, fibroblasts, smooth muscle cells, pericytes or other vascular wall cells underlie remodelling. In addition, immune cells, including macrophages and lymphocytes, may infiltrate vessels and initiate inflammatory signalling. They contribute to a dynamic interplay between cell proliferation, apoptosis, migration, inflammation, and extracellular matrix reorganisation, all critical mechanisms of vascular remodelling. Molecular pathways underlying these processes include growth factors (e.g., vascular endothelial growth factor and platelet-derived growth factor), inflammatory cytokines (e.g., interleukin-1β and tumour necrosis factor-α), reactive oxygen species, and signalling pathways, such as Rho/ROCK, MAPK, and TGF-β/Smad, related to nitric oxide and superoxide biology. MicroRNAs and long noncoding RNAs are crucial epigenetic regulators of gene expression in vascular remodelling. We evaluate these pathways for potential therapeutic targeting from a clinical translational perspective. In summary, vascular remodelling, a coordinated modification of vascular structure and function, is crucial in cardiovascular disease pathology.

Moyamoya Vasculopathy and Moyamoya-Related Systemic Vasculopathy: A Review With Histopathological and Genetic Viewpoints

Systemic vasculopathy has occasionally been reported in cases of moyamoya disease (MMD). Since the pathological relationship between moyamoya vasculopathy (MMV) and moyamoya-related systemic vasculopathy (MMRSV) remains unclear, it was examined herein by a review of histopathologic studies in consideration of clinicopathological and genetic viewpoints. Although luminal stenosis was a common finding in MMV and MMRSV, histopathologic findings of vascular remodeling markedly differed. MMV showed intimal hyperplasia, marked medial atrophy, and redundant tortuosity of the internal elastic lamina, with outer diameter narrowing called negative remodeling. MMRSV showed hyperplasia, mainly in the intima and sometimes in the media, with disrupted stratification of the internal elastic lamina. Systemic vasculopathy has also been observed in patients with non-MMD carrying the RNF213 (ring finger protein 213) mutation, leading to the concept of RNF213 vasculopathy. RNF213 vasculopathy in patients with non-MMD was histopathologically similar to MMRSV. Cases of MMRSV have sometimes been diagnosed with fibromuscular dysplasia. Fibromuscular dysplasia is similar to MMD not only in the histopathologic findings of MMRSV but also from clinicopathological and genetic viewpoints. The significant histopathologic difference between MMV and MMRSV may be attributed to a difference in the original vascular wall structure and its resistance to pathological stress between the intracranial and systemic arteries. To understand the pathogeneses of MMD and MMRSV, a broader perspective that includes RNF213 vasculopathy and fibromuscular dysplasia as well as an examination of the 2- or multiple-hit theory consisting of genetic factors, vascular structural conditions, and vascular environmental factors, such as blood immune cells and hemodynamics, are needed.

Cerebral arteriopathies of childhood and stroke - A focus on systemic arteriopathies and pediatric fibromuscular dysplasia (FMD)

Systemic vascular involvement in children with cerebral arteriopathies is increasingly recognized and often highly morbid. Fibromuscular dysplasia (FMD) represents a cerebral arteriopathy with systemic involvement, commonly affecting the renal and carotid arteries. In adults, FMD diagnosis and classification typically relies on angiographic features, like the 'string-of-beads' appearance, following exclusion of other diseases. Pediatric FMD (pFMD) is considered equivalent to adult FMD although robust evidence for similarities is lacking. We conducted a comprehensive literature review on pFMD and revealed inherent differences between pediatric and adult-onset FMD across various domains including epidemiology, natural history, histopathophysiology, clinical, and radiological features. Although focal arterial lesions are often described in children with FMD, the radiological appearance of 'string-of-beads' is highly nonspecific in children. Furthermore, children predominantly exhibit intimal-type fibroplasia, common in other childhood monogenic arteriopathies. Our findings lend support to the notion that pFMD broadly reflects an undefined heterogenous group of monogenic systemic medium-or-large vessel steno-occlusive arteriopathies rather than a single entity. Recognizing the challenges in categorizing complex morphologies of cerebral arteriopathy using current classifications, we propose a novel term for describing children with cerebral and systemic vascular involvement: 'cerebral and systemic arteriopathy of childhood' (CSA-c). This term aims to streamline patient categorization and, when coupled with advanced vascular imaging and high-throughput genomics, will enhance our comprehension of etiology, and accelerate mechanism-targeted therapeutic developments. Lastly, in light of the high morbidity in children with cerebral and systemic arteriopathies, we suggest that investigating for systemic vascular involvement is important in children with cerebral arteriopathies.

Spontaneous coronary artery dissection and fibromuscular dysplasia: insights into recent developments

Spontaneous coronary artery dissection (SCAD), an uncommon cause of acute coronary syndrome, continues to be a poorly understood disease predominantly affecting females. It is characterized by an abrupt separation in the coronary arterial wall due to intramural bleeding. Fibromuscular dysplasia (FMD) is a non-atherosclerotic arteriopathy manifesting in medium and small-sized arteries. It is a concomitant disease found among SCAD patients. In some studies, FMD prevalence in SCAD patients ranges between 25%-86%, which can be explained through varying screening techniques or modalities. The potential association has been elucidated in some studies; notably, not only has a genetic link been recently delineated between SCAD and FMD, but there is data to suggest that FMD not only can predispose to SCAD but can also be a potential predictor of its recurrence. However, a clear-cut correlation between the two has still not been established due to conflicting reports in the literature. To further dive into its pathology, it is crucial to highlight the importance of systematic screening in SCAD in order to identify associated risk factors and to be used as a method of FMD detection in such patients. Together, the two pathologies pose unique challenges in understanding its pathophysiology, diagnosis and management, as there is no clear evidence of a definitive treatment plan for patients with SCAD and FMD. A potentially beneficial modality of management is physical exercise, which is currently understudied in the long-term approach to treatment for patients with concomitant SCAD and FMD. Limited research in this field brings disadvantages to the understanding of the association between these two diseases, in order to give rise to better management recommendations. This mini-review aims to highlight the recent developments in the association between SCAD and FMD, its potential genetic association and some insights in screening, diagnosis, and management.

Vascular Diseases in Women: Do Women Suffer from Them Differently?

According to the World Health Organization, cardiovascular disease (CVD) is the leading cause of death among women worldwide, yet its magnitude is often underestimated. Biological and gender differences affect health, diagnosis, and healthcare in numerous ways. The lack of sex and gender awareness in health research and healthcare is an ongoing issue that affects not only research but also treatment and outcomes. The importance of recognizing the impacts of both sex and gender on health and of knowing the differences between the two in healthcare is beginning to gain ground. There is more appreciation of the roles that biological differences (sex) and sociocultural power structures (gender) have, and both sex and gender affect health behavior, the development of diseases, their diagnosis, management, and the long-term effects of an illness. An important issue is the knowledge and awareness of women about vascular diseases. The risk of cardiovascular events is drastically underestimated by women themselves, as well as by those around them. The purpose of this review is to draw attention to improving the medical care and treatment of women with vascular diseases.

A Rare Case of Focal Renal Fibromuscular Dysplasia Treated With Angioplasty: A Case Report

BACKGROUND

Fibromuscular dysplasia is an idiopathic, segmental, nonatherosclerotic, noninflammatory vascular disease that can lead to arterial stenosis, tortuosity, occlusion, aneurysms, and dissection. Fibromuscular dysplasia is a rare cause of hypertension that can easily be missed. To date, there has been no definitive treatment for fibromuscular dysplasia.

CASE REPORT

In this report, we present an uncommon case of renovascular hypertension in a 21-year-old non-white female with a 3-year history of hypertension secondary to fibromuscular dysplasia involving bilateral renal arteries. Computed tomography angiography during the arterial phase revealed distal focal narrowing of the right main renal artery, distal focal narrowing of the left main renal artery, and proximal focal narrowing of the left accessory lower renal artery. Percutaneous balloon dilatation of the stenotic lesion was performed successfully up to 1 year After the procedure, the arterial blood pressure was within the normal range (110/70 to 125/75 mmHg) without medication. After 1 year of follow-up, CTA revealed re-stenosis in left main renal artery without clinical symptoms and normal blood pressure. Repeated procedure was done successfully.

CONCLUSIONS

This case report highlights the difficulty in the diagnosis and treatment of focal fibromuscular dysplasia in young non-white female patients. Computerized tomographic angiography is a useful tool for identifying the cause and showing the benefit of percutaneous transluminal renal angioplasty treatment for this rare entity, as an early percutaneous angioplasty intervention may have a clinical cure for hypertension.

Next Generation Sequencing and Electromyography Reveal the Involvement of the P2RX6 Gene in Myopathy

Ion channelopathies result from impaired ion channel protein function, due to mutations affecting ion transport across cell membranes. Over 40 diseases, including neuropathy, pain, migraine, epilepsy, and ataxia, are associated with ion channelopathies, impacting electrically excitable tissues and significantly affecting skeletal muscle. Gene mutations affecting transmembrane ionic flow are strongly linked to skeletal muscle disorders, particularly myopathies, disrupting muscle excitability and contraction. Electromyography (EMG) analysis performed on a patient who complained of weakness and fatigue revealed the presence of primary muscular damage, suggesting an early-stage myopathy. Whole exome sequencing (WES) did not detect potentially causative variants in known myopathy-associated genes but revealed a novel homozygous deletion of the P2RX6 gene likely disrupting protein function. The P2RX6 gene, predominantly expressed in skeletal muscle, is an ATP-gated ion channel receptor belonging to the purinergic receptors (P2RX) family. In addition, STRING pathways suggested a correlation with more proteins having a plausible role in myopathy. No previous studies have reported the implication of this gene in myopathy. Further studies are needed on patients with a defective ion channel pathway, and the use of in vitro functional assays in suppressing P2RX6 gene expression will be required to validate its functional role.

Differentiating between segmental arterial mediolysis and other arterial vasculopathies to establish an early diagnosis - a systematic literature review and proposal of new diagnostic criteria

Segmental arterial mediolysis (SAM) is a rare vascular disease, characterized by acute but transient vulnerability of the wall of medium-sized arteries. The most characteristic feature of SAM is its biphasic course: an injurious phase marked by acute weakness of the arterial wall leading to acute dissection and/or hemorrhage, followed by a reparative phase in which granulation tissue and fibrosis restore the injured arterial wall. Residual stenosis, aneurysms, and/or arterial wall irregularities may remain visible on future imaging studies. Differentiating between SAM and other arterial vasculopathies is difficult due to its similarities with many other vascular diseases, such as vasculitis, fibromuscular dysplasia, inherited connective tissue disorders, and isolated visceral artery dissection. In this systematic review, we provide an overview on SAM, with an emphasis on the differential diagnosis and diagnostic work-up. We propose new diagnostic criteria to help establish a prompt diagnosis of SAM, illustrated by case examples from our multidisciplinary vascular clinic.

Fibromuscular Dysplasia: Three Cases to Highlight a Requirement for Surveillance Strategy Optimization

Fibromuscular dysplasia (FMD) is a rare vascular disease with broad, potentially severe complications. We present three cases of FMD covering the spectrum of clinical presentations involving the abdominal and visceral vasculature, and highlight the potential role of high-risk genotype detection in assisting with the determination of which patients may benefit from a more aggressive surveillance strategy.

Cerebrovascular Fibromuscular Dysplasia - A Practical Review

Fibromuscular dysplasia (FMD) is a rare idiopathic, segmental, noninflammatory and nonatherosclerotic arteriopathy of medium-sized arteries. It is classically considered to be a disease of young and middle adulthood, with females more commonly affected than males. FMD is a systemic disease. Although historically considered to be rare, cerebrovascular FMD (C-FMD) has now been recognized to be as common as the renovascular counterpart. Extracranial carotid and vertebral arteries are the most commonly involved vascular territories in C-FMD with the clinical presentation determined by vessels affected. Common symptoms include headaches and pulsatile tinnitus, with transient ischemic attacks, ischemic stroke and subarachnoid or intracerebral hemorrhage constituting the more severe clinical manifestations. Cervical artery dissection involving carotids more often than vertebral arteries and intracranial aneurysms account for the cerebrovascular pathologies detected in C-FMD. Our understanding regarding C-FMD has been augmented in the recent past on account of dedicated C-FMD data from North American, European and other international FMD cohorts. In this review article, we provide an updated and comprehensive overview on epidemiology, clinical presentation, etiology, diagnosis and management of C-FMD.

Spontaneous Coronary Artery Dissection: Review of Possible Pathophysiological Risk Factors

Spontaneous coronary artery dissection (SCAD) is a rare cause of acute coronary syndrome (ACS) that typically affects the younger and healthier female population without the typical ACS risk factors such as hypertension, diabetes, or hyperlipidemia. The clinical presentation of SCAD can be diverse and the diagnosis is typically by coronary angiography but also can require advanced imaging such as intravascular ultrasound or optical coherence tomography. Past studies have shown the atypical patient characteristics of SCAD patients among ACS patients. The main challenge is that the exact pathophysiology of SCAD is unknown. Potential pathophysiological risk factors are discussed including fibromuscular dysplasia, other arteriopathies, pregnancy and female sex hormone changes, migraines, inflammatory conditions, and stress. The current understanding of these risk factors along with potential pathophysiological mechanisms are discussed. There still remain many areas of additional investigation in understanding this rare cause of ACS.

Fibromuscular Dysplasia Presenting as Acute Unilateral Renal Infarction: A Case Report and Review of Two Diseases

Fibromuscular dysplasia (FMD) is a rare systemic vascular disease that has been found to present as a renal infarction (RI) in only a handful of cases.  We present a case of a 53-year-old Vietnamese patient presenting for sharp, severe left-sided abdominal pain of two-day duration associated with a migraine headache. On presentation, she was afebrile, and her vital signs were stable. Laboratory investigations were significant for mildly elevated leukocytosis but were otherwise normal. CT abdomen and pelvis with contrast revealed a left-sided renal infarct. The patient was then admitted to the hospital and started on therapeutic anticoagulation. A transthoracic echocardiogram was obtained and revealed no vegetation. CT angiography of the abdomen was pursued and was significant for mild beading within the mid-right and left renal arteries, consistent with fibromuscular dysplasia. Our patient was diagnosed with renal infarction in the setting of fibromuscular dysplasia, a combination that has been reported only a few times. Interestingly, our patient also had mild FMD based on imaging, making it even more of an unusual cause of renal infarction. This case highlights the connection between these two diseases and the need for more studies to characterize the association between them.

Association of Spontaneous Coronary Artery Dissection With Atrial Arrhythmias

The co-morbidities and long-term complications of spontaneous coronary artery dissection (SCAD) are incompletely understood. This study investigated the association of atrial arrhythmias (AA), defined as atrial fibrillation and atrial flutter, with SCAD in a patient registry and population-based cohort. This observational study was performed in 2 parts. The first was a retrospective study reviewing patients diagnosed with AA in the Mayo Clinic SCAD Registry. The second was a population-based, case-control study to assess AA in patients with SCAD compared with age- and gender-matched controls. Of 1,214 patients in the Mayo Clinic SCAD Registry, 45 patients (3.7%) with SCAD were identified with an AA. A total of 8 of those patients (17.8%) had a pre-SCAD AA; 20 (44.4%) had a peri-SCAD AA; and 17 (37.8%) had a post-SCAD AA. The univariate analysis did not reveal significant associations with traditional cardiovascular risk factors. In the population-based cohort, 5 patients with SCAD (4%) and 4 controls (1%) developed an AA before the date of SCAD for each patient (odds ratio 4.5, 95% confidence interval [CI] 1.05 to 19.0, p = 0.04). A total of 5 patients with SCAD (4%) and 3 controls (1%) developed an AA in the 10 years after SCAD (hazard ratio 6.3, 95% CI 1.2 to 32.8, p = 0.03). A subgroup of patients with SCAD experienced AA before and after SCAD. Patients with a history of SCAD were more likely to develop AA in the next 10 years than were age- and gender-matched healthy controls.

Increased Collagen Turnover Is a Feature of Fibromuscular Dysplasia and Associated With Hypertrophic Radial Remodeling: A Pilot, Urine Proteomic Study

Fibromuscular dysplasia (FMD), a nonatherosclerotic, noninflammatory disease of medium-sized arteries, is an underdiagnosed disease. We investigated the urinary proteome and developed a classifier for discrimination of FMD from healthy controls and other diseases. We further hypothesized that urinary proteomics biomarkers may be associated with alterations in medium-sized, but not large artery geometry and mechanics. The study included 33 patients with mostly multifocal, renal FMD who underwent in depth arterial exploration using ultra-high frequency ultrasound. The cohort was separated in a training set of 23 patients with FMD from Belgium and an independent test set of 10 patients with FMD from Italy. For each set, controls matched 2:1 were selected from the Human Urinary Proteome Database. The specificity of the classifier was tested in 700 additional controls from general population studies, patients with chronic kidney disease (n=66) and coronary artery disease (n=31). Three hundred thirty-five urinary peptides, mostly related to collagen turnover, were identified in the training cohort and combined into a classifier. When applying in the test cohort, the area under the receiver operating characteristic curve was 1.00, 100% specificity at 100% sensitivity. The classifier maintained a high specificity in additional controls (98.3%), patients with chronic kidney (90.9%) and coronary artery (96.8%) diseases. Furthermore, in patients with FMD, the proteomic score was positively associated with radial wall thickness and wall cross-sectional area. In conclusion, a proteomic score has the potential to discriminate between patients with FMD and controls. If confirmed in a wider and more diverse cohort, these findings may pave the way for a noninvasive diagnostic test of FMD.

Fibromuscular dysplasia in a middle-aged transgender man: The role of hormones in disease pathogenesis

Fibromuscular dysplasia is an uncommon non-inflammatory arteriopathy. Hormonal factors are believed to play a role in disease pathogenesis given the overwhelming female predominance of this disease. We describe a case of a 56-year-old transgender man on prolonged testosterone therapy diagnosed with renal fibromuscular dysplasia after presenting with hypertensive urgency.