Mitral valve prolapse and mitral regurgitation are common in patients with polycystic kidney disease type 1

Overview of clinical status, treatment, and long-term outcomes of pediatric autosomal-dominant polycystic kidney disease: a nationwide survey in Taiwan

This retrospective study investigated the incidence, medication use, and outcomes in pediatric autosomal-dominant polycystic kidney disease (ADPKD) using Taiwan's National Health Insurance Research Database (NHIRD). A 1:4 matched control group of individuals included in the NHIRD during the same period was used for comparative analyses. A total of 621 pediatric patients were identified from 2009 to 2019 (mean age, 9.51 ± 6.43 years), and ADPKD incidence ranged from 2.32 to 4.45 per 100,000 individuals (cumulative incidence, 1.26-1.57%). The incidence of newly developed hypertension, anti-hypertensive agent use, nephrolithiasis, and proteinuria were significantly higher in the ADPKD group than the non-ADPKD group (0.7 vs. 0.04, 2.26 vs. 0.30, 0.4 vs. 0.02, and 0.73 vs. 0.05 per 100 person-years, respectively). The adjusted hazard ratios for developing hypertension, proteinuria, nephrolithiasis and anti-hypertensive agent use in cases of newly-diagnosed pediatric ADPKD were 12.36 (95% CI 4.92-31.0), 13.49 (95% CI 5.23-34.79), 13.17 (95% CI 2.48-69.98), and 6.38 (95% CI 4.12-9.89), respectively. The incidence of congenital cardiac defects, hematuria, urinary tract infections, gastrointestinal diverticulosis, dyslipidemia, and hyperuricemia were also higher in the ADPKD group. Our study offers valuable insights into the epidemiology of pediatric ADPKD in Taiwan and could help in formulating guidelines for its appropriate management.

Cardiovascular Manifestations and Management in ADPKD

Cardiovascular disease (CVD) is the major cause of mortality in autosomal dominant polycystic kidney disease (ADPKD) and contributes to significant burden of disease. The manifestations are varied, including left ventricular hypertrophy (LVH), intracranial aneurysms (ICAs), valvular heart disease, and cardiomyopathies; however, the most common presentation and a major modifiable risk factor is hypertension. The aim of this review is to detail the complex pathogenesis of hypertension and other extrarenal cardiac and vascular conditions in ADPKD drawing on preclinical, clinical, and epidemiological evidence. The main drivers of disease are the renin-angiotensin-aldosterone system (RAAS) and polycystin-related endothelial cell dysfunction, with the sympathetic nervous system (SNS), nitric oxide (NO), endothelin-1 (ET-1), and asymmetric dimethylarginine (ADMA) likely playing key roles in different disease stages. The reported rates of some manifestations, such as LVH, have decreased likely due to the use of antihypertensive therapies; and others, such as ischemic cardiomyopathy, have been reported with increased prevalence likely due to longer survival and higher rates of chronic disease. ADPKD-specific screening and management guidelines exist for hypertension, LVH, and ICAs; and these are described in this review.

Dialysis and Transplant Considerations in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is the fourth leading cause of kidney replacement therapy. Unfortunately, the need for dialysis or kidney transplantation is a foreseeable outcome for many patients affected by ADPKD. We review some of the unique issues that should be considered in the management of patients with ADPKD who require dialysis or kidney transplantation. The choice of dialysis modality may be influenced by the enlarged kidneys and liver, but peritoneal dialysis should not be excluded as an option, as studies do not consistently show that there is an increased risk for technique failure or peritonitis. The optimal kidney replacement therapy option remains kidney transplantation; however, nephrectomy may be needed if there is insufficient space for the allograft. Living donor candidates from at-risk families need to be excluded from carrying the disease either by diagnostic imaging criteria or genetic testing. Other potential transplant issues, such as malignancy and cardiovascular and metabolic risks, should also be recognized. Despite these issues, patients with ADPKD requiring dialysis or kidney transplantation generally have more favorable outcomes as compared to those with other causes of chronic kidney disease. Further studies are still needed to personalize the therapeutic approach for those receiving kidney replacement therapy and eventually improve clinical outcomes.

Management of Hypertension and Associated Cardiovascular Disease in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease is the most commonly inherited disease of the kidneys affecting an estimated 12,000,000 people in the world. Autosomal dominant polycystic kidney disease is a systemic disease, with a wide range of associated features that includes hypertension, valvular heart diseases, cerebral aneurysms, aortic aneurysms, liver cysts, abdominal hernias, diverticulosis, gross hematuria, urinary tract infections, nephrolithiasis, pancreatic cysts, and seminal vesicle cysts. The cardiovascular anomalies are somewhat different than in the general population and also chronic kidney disease population, with higher morbidity and mortality rates. This review will focus on cardiovascular diseases associated with autosomal dominant polycystic kidney disease and their management.

Biology of mitral valve prolapse: from general mechanisms to advanced molecular patterns-a narrative review

Mitral valve prolapse (MVP) represents the most frequent cause of primary mitral regurgitation. For several years, biological mechanisms underlying this condition attracted the attention of investigators, trying to identify the pathways responsible for such a peculiar condition. In the last ten years, cardiovascular research has moved from general biological mechanisms to altered molecular pathways activation. Overexpression of TGF-β signaling, for instance, was shown to play a key role in MVP, while angiotensin-II receptor blockade was found to limit MVP progression by acting on the same signaling pathway. Concerning extracellular matrix organization, the increased valvular interstitial cells density and dysregulated production of catalytic enzymes (matrix metalloproteinases above all) altering the homeostasis between collagen, elastin and proteoglycan components, have been shown to possibly provide a mechanistic basis contributing to the myxomatous MVP phenotype. Moreover, it has been observed that high levels of osteoprotegerin may contribute to the pathogenesis of MVP by increasing collagen deposition in degenerated mitral leaflets. Although MVP is believed to represent the result of multiple genetic pathways alterations, it is important to distinguish between syndromic and non-syndromic conditions. In the first case, such as in Marfan syndrome, the role of specific genes has been clearly identified, while in the latter a progressively increasing number of genetic loci have been thoroughly investigated. Moreover, genomics is gaining more interest as potential disease-causing genes and loci possibly associated with MVP progression and severity have been identified. Animal models could be of help in better understanding the molecular basis of MVP, possibly providing sufficient information to tackle specific mechanisms aimed at slowing down MVP progression, therefore developing non-surgical therapies impacting on the natural history of this condition. Although continuous progress has been made in this field, further translational studies are advocated to improve our knowledge of biological mechanisms underlying MVP development and progression.

Prevalence of cardiac valvar abnormalities in children and young people with autosomal dominant polycystic kidney disease

BACKGROUND

Valvar abnormalities in children and adults with autosomal dominant polycystic kidney disease (ADPKD) have previously been reported as a frequent occurrence. Mitral valve prolapse (MVP), in particular, has been reported in almost one-third of adult patients and nearly 12% of children with ADPKD. Our objective in this study was to establish the prevalence of valvar abnormalities in a large, contemporary series of children and young people (CYP) with ADPKD.

METHODS

A retrospective, single centre, cross-sectional analysis of the echocardiograms performed on all consecutive children seen in a dedicated paediatric ADPKD clinic. Full anatomical and functional echocardiograms were performed and analysed for valvar abnormalities.

RESULTS

The echocardiograms of 102 CYP with ADPKD (range 0.25-18 years, mean age 10.3 years, SD ± 5.3 years) were analysed. One (0.98%), 3-year-old boy, had MVP. There was no associated mitral regurgitation. Evaluating variations in normal valvar anatomy, 9 (8.8%) patients, aged 7.1 to 18 years, had minor bowing ± visual elongation of either the anterior or posterior leaflet of the mitral valve, none of which fell within the criteria of true MVP. Three (1.9%) patients, 2 boys and 1 girl aged between 7 and 14 years, had trivial or mild aortic regurgitation. No patients had echocardiographic evidence of tricuspid valve prolapse (TVP).

CONCLUSION

In this contemporary cohort of CYP with ADPKD, the incidence of MVP and other valvar lesions is significantly lower than previously reported. A higher resolution version of the Graphical abstract is available as Supplementary information.

Cardiac Manifestations in Patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD): A Single-Center Study

Key Points

Cardiovascular disease—a key driver of morbidity in CKD—is common in patients with autosomal dominant polycystic kidney disease (ADPKD). Pathologic echocardiography findings, including valvular defects, aortic root dilation, and hypertrophy, are found in most patients with ADPKD. These findings correlate with parameters indicating disease progression in ADPKD. Echocardiography should be offered to all patients with ADPKD.

Background

ADPKD is the most common monogenetic kidney disease and results in kidney failure in >75% of affected individuals. As a systemic disorder, ADPKD is associated with a variety of extrarenal manifestations, including cardiac manifestations, that affect the majority of patients. We characterized the cardiac involvement in patients with ADPKD from the German AD(H)PKD registry and compared them with kidney donor candidates as controls.

Methods

In this single-center cohort study, we evaluated 141 patients with ADPKD (44.17±11.23 years) from the German AD(H)PKD registry and 60 kidney donor candidates (55.08±10.21 years). All patients underwent clinical examination, abdominal MRI, and transthoracic echocardiography.

Results

Of the patients with ADPKD, 65% showed hypertrophy of the left ventricle (as defined by an end-diastolic interventricular septal wall thickness [IVSd] >10 mm) compared with 55% in control patients. Mitral regurgitation was the most common finding among 54% of patients with ADPKD who exhibited valvular dysfunction, albeit mild in most patients. Interestingly, left ventricular ejection fraction (LV-EF) differed significantly between both groups, with higher values in patients with ADPKD (64%±6% versus 60%±6%), whereas other parameters, including IVSd, left ventricular end-diastolic diameter (LVEDD), tricuspid annular plane systolic excursion (TAPSE), and pressure gradients across the aortic and tricuspid valve were similar between groups. Correlations of echocardiographic parameters with markers of disease progression revealed statistically significant associations for aortic root diameter (P =0.01), the pressure gradient across the aortic valve (AV dPmax; P =0.0003), and IVSd (P =0.0001), indicating rapid kidney disease progression may also be associated with cardiac findings.

Conclusion

Cardiovascular abnormalities are prevalent in patients with ADPKD. Considering the importance of cardiovascular disease for outcomes in CKD, early management and possibly prevention are important goals of any treatment scheme. Consequently, echocardiography should be offered to all patients with ADPKD in routine management.

Multiple pkd and piezo gene family members are required for atrioventricular valve formation

Cardiac valves ensure unidirectional blood flow through the heart, and altering their function can result in heart failure. Flow sensing via wall shear stress and wall stretching through the action of mechanosensors can modulate cardiac valve formation. However, the identity and precise role of the key mechanosensors and their effectors remain mostly unknown. Here, we genetically dissect the role of Pkd1a and other mechanosensors in atrioventricular (AV) valve formation in zebrafish and identify a role for several pkd and piezo gene family members in this process. We show that Pkd1a, together with Pkd2, Pkd1l1, and Piezo2a, promotes AV valve elongation and cardiac morphogenesis. Mechanistically, Pkd1a, Pkd2, and Pkd1l1 all repress the expression of klf2a and klf2b, transcription factor genes implicated in AV valve development. Furthermore, we find that the calcium-dependent protein kinase Camk2g is required downstream of Pkd function to repress klf2a expression. Altogether, these data identify, and dissect the role of, several mechanosensors required for AV valve formation, thereby broadening our understanding of cardiac valvulogenesis.

Echocardiographic Abnormalities in Autosomal Dominant Polycystic Kidney Disease (ADPKD) Patients

Cardiovascular abnormalities, such as left ventricular hypertrophy and valvular disorders, particularly mitral valve prolapse, have been described as highly prevalent among adult patients with autosomal dominant polycystic kidney disease (ADPKD). The present study aimed to assess echocardiographic parameters in a large sample of both normotensive and hypertensive ADPKD patients, regardless of kidney function level, and evaluate their association with clinical and laboratorial parameters. A retrospective study consisted of the analysis of clinical, laboratorial, and transthoracic echocardiograms data retrieved from the medical records of young adult ADPKD outpatients. A total of 294 patients (120 M/174 F, 41.0 ± 13.8 years old, 199 hypertensive and 95 normotensive) with a median estimated glomerular filtration rate (eGFR) of 75.5 mL/min/1.73 m² were included. The hypertensive group (67.6%) was significantly older and exhibited significantly lower eGFR than the normotensive one. Increased left ventricular mass index (LVMI) was seen in 2.0%, mitral valve prolapse was observed in 3.4%, mitral valve regurgitation in 15.3%, tricuspid valve regurgitation in 16.0%, and aortic valve regurgitation in 4.8% of the whole sample. The present study suggested that the prevalence of mitral valve prolapse was much lower than previously reported, and increased LVMI was not seen in most adult ADPKD patients.

Cardiovascular Outcomes in Kidney Transplant Recipients With ADPKD

Introduction

Cardiovascular disease leads to high morbidity and mortality in patients with kidney failure. Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic disease with various cardiac abnormalities. Details on the cardiovascular profile of patients with ADPKD who are undergoing kidney transplantation (KT) and its progression are limited.

Methods

Echocardiographic data within 2 years before KT (1993-2020), and major adverse cardiovascular events (MACEs) after transplantation were retrieved. The primary outcome is to assess cardiovascular abnormalities on echocardiography at the time of transplantation in ADPKD as compared with patients without ADPKD matched by sex (male, 59.4%) and age at transplantation (57.2 ± 8.8 years).

Results

Compared with diabetic nephropathy (DN, n = 271) and nondiabetic, patients without ADPKD (NDNA) (n = 271) at the time of KT, patients with ADPKD (n = 271) had lower rates of left ventricular hypertrophy (LVH) (39.4% vs. 66.4% vs. 48.6%), mitral (2.7% vs. 6.3% vs. 7.45) and tricuspid regurgitations (1.8% vs. 6.6% vs. 7.2%). Patients with ADPKD had less diastolic (25.3%) and systolic (5.6%) dysfunction at time of transplantation. Patients with ADPKD had the most favorable post-transplantation survival (median 18.7 years vs. 12.0 for diabetic nephropathy [DN] and 13.8 years for nondiabetic non-ADPKD [NDNA]; P < 0.01) and the most favorable MACE-free survival rate (hazard ratio = 0.51, P < 0.001). Patients with ADPKD had worsening of their valvular function and an increase in the sinus of Valsalva diameter post-transplantation (38.2 vs. 39.9 mm, P < 0.01).

Conclusion

ADPKD transplant recipients have the most favorable cardiac profile pretransplantation with better patient survival and MACE-free survival rates but worsening valvular function and increasing sinus of Valsalva diameter, as compared with patients with other kidney diseases.

Hedgehog Morphogens Act as Growth Factors Critical to Pre- and Postnatal Cardiac Development and Maturation: How Primary Cilia Mediate Their Signal Transduction

Primary cilia are crucial for normal cardiac organogenesis via the formation of cyto-architectural, anatomical, and physiological boundaries in the developing heart and outflow tract. These tiny, plasma membrane-bound organelles function in a sensory-integrative capacity, interpreting both the intra- and extra-cellular environments and directing changes in gene expression responses to promote, prevent, and modify cellular proliferation and differentiation. One distinct feature of this organelle is its involvement in the propagation of a variety of signaling cascades, most notably, the Hedgehog cascade. Three ligands, Sonic, Indian, and Desert hedgehog, function as growth factors that are most commonly dependent on the presence of intact primary cilia, where the Hedgehog receptors Patched-1 and Smoothened localize directly within or at the base of the ciliary axoneme. Hedgehog signaling functions to mediate many cell behaviors that are critical for normal embryonic tissue/organ development. However, inappropriate activation and/or upregulation of Hedgehog signaling in postnatal and adult tissue is known to initiate oncogenesis, as well as the pathogenesis of other diseases. The focus of this review is to provide an overview describing the role of Hedgehog signaling and its dependence upon the primary cilium in the cell types that are most essential for mammalian heart development. We outline the breadth of developmental defects and the consequential pathologies resulting from inappropriate changes to Hedgehog signaling, as it pertains to congenital heart disease and general cardiac pathophysiology.

Echocardiographic Findings and Genotypes in Autosomal Dominant Polycystic Kidney Disease

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary cystic kidney disease and is well known to have extrarenal complications. Cardiovascular complications are of particular clinical relevance because of their morbidity and mortality; however, unclear is why they occur so frequently in patients with ADPKD and whether they are related to the genotypes.

Methods

We extracted and retrospectively analyzed clinical data on patients with ADPKD who underwent echocardiography and whose genotype was confirmed by genetic testing between April 2016 and December 2020. We used next-generation sequencing to compare cardiac function, structural data, and the presence of cardiac valvular disease in patients with 1 of 3 genotypes: PKD1, PKD2, and non-PKD1, 2.

Results

This retrospective study included 65 patients with ADPKD. Patients were divided into 3 groups: PKD1, n = 32; PKD2, n = 12; and non-PKD1, 2, n = 21. The prevalence of mitral regurgitation (MR) was significantly higher in the PKD1 group than in the PKD2 and non-PKD1, 2 group (46.9% vs. 8.3% vs. 19.0%, respectively; p = 0.02). In contrast, no significant difference was found for other cardiac valve complications.

Conclusion

This study found a significantly higher prevalence of MR in patients with the PKD1 genotype than in those with the PKD2 or non-PKD1, 2 genotypes. Physicians may need to perform echocardiography earlier and more frequently in patients with ADPKD and the PKD1 genotype and to control fluid volume and blood pressure more strictly in these patients to prevent future cardiac events.

A change of heart: new roles for cilia in cardiac development and disease

Although cardiac abnormalities have been observed in a growing class of human disorders caused by defective primary cilia, the function of cilia in the heart remains an underexplored area. The primary function of cilia in the heart was long thought to be restricted to left-right axis patterning during embryogenesis. However, new findings have revealed broad roles for cilia in congenital heart disease, valvulogenesis, myocardial fibrosis and regeneration, and mechanosensation. In this Review, we describe advances in our understanding of the mechanisms by which cilia function contributes to cardiac left-right axis development and discuss the latest findings that highlight a broader role for cilia in cardiac development. Specifically, we examine the growing line of evidence connecting cilia function to the pathogenesis of congenital heart disease. Furthermore, we also highlight research from the past 10 years demonstrating the role of cilia function in common cardiac valve disorders, including mitral valve prolapse and aortic valve disease, and describe findings that implicate cardiac cilia in mechanosensation potentially linking haemodynamic and contractile forces with genetic regulation of cardiac development and function. Finally, given the presence of cilia on cardiac fibroblasts, we also explore the potential role of cilia in fibrotic growth and summarize the evidence implicating cardiac cilia in heart regeneration.

Pericardial Effusion on MRI in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) has been associated with cardiac abnormalities including mitral valve prolapse and aneurysmal dilatation of the aortic root. Herein, we investigated the potential association of pericardial effusion with ADPKD. Subjects with ADPKD (n = 117) and control subjects without ADPKD matched for age, gender and renal function (n = 117) undergoing MRI including ECG-gated cine MRI of the aorta and heart were evaluated for pericardial effusion independently by three observers measuring the maximum pericardial effusion thickness in diastole using electronic calipers. Pericardial effusion thickness was larger in ADPKD subjects compared to matched controls (Mann-Whitney p = 0.001) with pericardial effusion thickness >5 mm observed in 24 of 117 (21%) ADPKD subjects compared to 4 of 117 (3%) controls (p = 0.00006). Pericardial effusion thickness in ADPKD was associated with female gender patients (1.2 mm greater than in males, p = 0.03) and pleural effusion thickness (p < 0.001) in multivariate analyses. No subjects exhibited symptoms related to pericardial effusion or required pericardiocentesis. In conclusion, pericardial effusion appears to be more prevalent in ADPKD compared to controls. Although in this retrospective cross-sectional study we did not identify clinical significance, future investigations of pericardial effusion in ADPKD subjects may help to more fully understand its role in this disease.

Mitral Valve Prolapse and Its Motley Crew-Syndromic Prevalence, Pathophysiology, and Progression of a Common Heart Condition

Mitral valve prolapse (MVP) is a commonly occurring heart condition defined by enlargement and superior displacement of the mitral valve leaflet(s) during systole. Although commonly seen as a standalone disorder, MVP has also been described in case reports and small studies of patients with various genetic syndromes. In this review, we analyzed the prevalence of MVP within syndromes where an association to MVP has previously been reported. We further discussed the shared biological pathways that cause MVP in these syndromes, as well as how MVP in turn causes a diverse array of cardiac and noncardiac complications. We found 105 studies that identified patients with mitral valve anomalies within 18 different genetic, developmental, and connective tissue diseases. We show that some disorders previously believed to have an increased prevalence of MVP, including osteogenesis imperfecta, fragile X syndrome, Down syndrome, and Pseudoxanthoma elasticum, have few to no studies that use up-to-date diagnostic criteria for the disease and therefore may be overestimating the prevalence of MVP within the syndrome. Additionally, we highlight that in contrast to early studies describing MVP as a benign entity, the clinical course experienced by patients can be heterogeneous and may cause significant cardiovascular morbidity and mortality. Currently only surgical correction of MVP is curative, but it is reserved for severe cases in which irreversible complications of MVP may already be established; therefore, a review of clinical guidelines to allow for earlier surgical intervention may be warranted to lower cardiovascular risk in patients with MVP.

Cardiac Involvement in Autosomal Dominant Polycystic Kidney Disease

Cardiovascular disorders are the main complication in autosomal dominant polycystic kidney disease (ADPKD). contributing to both morbidity and mortality. This review considers clinical studies unveiling cardiovascular features in patients with ADPKD. Additionally, it focuses on basic science studies addressing the dysfunction of the polycystin proteins located in the cardiovascular system as a contributing factor to cardiovascular abnormalities. In particular, the effects of polycystin proteins’ deficiency on the cardiomyocyte function have been considered.

Aortic Dissection in Familial Patients with Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common congenital kidney disease. However, reports on occasional cases of aortic dissection in PKD familial patients remain scarce. Herein, we describe rare aortic dissection cases in PKD familial patients (i.e., mother and daughter) and our successful treatment experience. The mother (84 years old) and daughter (53 years old) had a referral to us to treat type A acute aortic dissection. We performed emergency surgery and successfully treated the patients with an artificial graft. For comprehensive evaluation and treatment, ADPKD patients and their families should be screened for aortic diseases.

[Cardiovascular disorders in autosomal dominant polycystic kidney disease]

Autosomal dominant polycystic kidney disease is the most frequent genetic kidney disease. Cardiovascular disorders associated with autosomal dominant polycystic kidney disease are multiple and may occur early in life. In autosomal dominant polycystic kidney disease cardiovascular morbidity and mortality are related both to the nonspecific consequences of chronic kidney disease and to the particular phenotype of autosomal dominant polycystic kidney disease. Compared to the general population, patients with autosomal dominant polycystic kidney disease present an increased prevalence of hypertension, left ventricular hypertrophy, atrial fibrillation, valvular diseases, aneurisms and arterial dissections. This review article provides an update on cardiovascular disorders associated with autosomal dominant polycystic kidney disease and recent pathophysiological developments.

Primary cilia defects causing mitral valve prolapse

Mitral valve prolapse (MVP) affects 1 in 40 people and is the most common indication for mitral valve surgery. MVP can cause arrhythmias, heart failure, and sudden cardiac death, and to date, the causes of this disease are poorly understood. We now demonstrate that defects in primary cilia genes and their regulated pathways can cause MVP in familial and sporadic nonsyndromic MVP cases. Our expression studies and genetic ablation experiments confirmed a role for primary cilia in regulating ECM deposition during cardiac development. Loss of primary cilia during development resulted in progressive myxomatous degeneration and profound mitral valve pathology in the adult setting. Analysis of a large family with inherited, autosomal dominant nonsyndromic MVP identified a deleterious missense mutation in a cilia gene, DZIP1 A mouse model harboring this variant confirmed the pathogenicity of this mutation and revealed impaired ciliogenesis during development, which progressed to adult myxomatous valve disease and functional MVP. Relevance of primary cilia in common forms of MVP was tested using pathway enrichment in a large population of patients with MVP and controls from previously generated genome-wide association studies (GWAS), which confirmed the involvement of primary cilia genes in MVP. Together, our studies establish a developmental basis for MVP through altered cilia-dependent regulation of ECM and suggest that defects in primary cilia genes can be causative to disease phenotype in some patients with MVP.

Role of cilia in the pathogenesis of congenital heart disease

An essential role for cilia in the pathogenesis of congenital heart disease (CHD) has emerged from findings of a large-scale mouse forward genetic screen. High throughput screening with fetal ultrasound imaging followed by whole exome sequencing analysis recovered a preponderance of cilia related genes and cilia transduced cell signaling genes among mutations identified to cause CHD. The perturbation of left-right patterning in CHD pathogenesis is suggested by the association of CHD with heterotaxy, but also by the finding of the co-occurrence of laterality defects with CHD in birth defect registries. Many of the cilia and cilia cell signaling genes recovered were found to be related to Hedgehog signaling. Studies in mice showed cilia transduced hedgehog signaling coordinates left-right patterning with heart looping and differentiation of the heart tube. Cilia transduced Shh signaling also regulates later events in heart development, including outflow tract septation and formation of the atrioventricular septum. More recent work has shown mutations in cilia related genes may also contribute to valve disease that largely manifest in adult life. Overall, these and other findings show cilia play an important role in CHD and also in more common valve diseases.

Polycystins, ADPKD, and Cardiovascular Disease

Cardiovascular disorders are the most common cause of mortality in autosomal dominant polycystic kidney disease (ADPKD). This review considers recent clinical and basic science studies that address the contributing factors of cardiovascular dysfunction in ADPKD. In particular, attention is placed on how dysfunction of the polycystin proteins located in the cardiovascular system contributes to extrarenal manifestations of ADPKD.

Hyperactivity of Mek in TNS1 knockouts leads to potential treatments for cystic kidney diseases

Cystic kidney disease is the progressive development of multiple fluid-filled cysts that may severely compromise kidney functions and lead to renal failure. TNS1 (tensin-1) knockout mice develop cystic kidneys and die from renal failure. Here, we have established TNS1-knockout MDCK cells and applied 3D culture system to investigate the mechanism leading to cyst formation. Unlike wild-type MDCK cells, which form cysts with a single lumen, TNS1-knockout cysts contain multiple lumens and upregulated Mek/Erk activities. The multiple lumen phenotype and Mek/Erk hyperactivities are rescued by re-expression of wild-type TNS1 but not the TNS1 mutant lacking a fragment essential for its cell–cell junction localization. Furthermore, Mek inhibitor treatments restore the multiple lumens back to single lumen cysts. Mek/Erk hyperactivities are also detected in TNS1-knockout mouse kidneys. Treatment with the Mek inhibitor trametinib significantly reduces the levels of interstitial infiltrates, fibrosis and dilated tubules in TNS1-knockout kidneys. These studies establish a critical role of subcellular localization of TNS1 in suppressing Mek/Erk signaling and maintaining lumenogenesis, and provide potential therapeutic strategies by targeting the Mek/Erk pathway for cystic kidney diseases.

Left ventricular hypertrophy in a contemporary cohort of autosomal dominant polycystic kidney disease patients

Background

Patients with Autosomal Dominant Polycystic Kidney Disease (ADPKD) often develop hypertension in childhood or early adulthood. Although this could result in left ventricular hypertrophy (LVH), a major risk factor for cardiovascular morbidity and mortality, prior studies of LVH in ADPKD have yielded conflicting results. We estimated the prevalence of LVH using consensus echocardiography criteria and examined the independent association of ADPKD severity with LV mass in a contemporary cohort of ADPKD patients.

Methods

Adults with ADPKD and eGFR> 15 ml/min/1.73m² were enrolled in a single-center study. Left Ventricular Mass (LVM) was quantified using 2D echocardiography, and LVH was defined using gender-specific cut-points of LVM and LVM indexed to body surface area (LVMI) from consensus guidelines. Total Kidney Volume (TKV) was quantified using Magnetic Resonance Imaging, and GFR was estimated from serum creatinine using the CKD-Epi equation. Multiple linear regression was used to estimate the association of TKV and eGFR with LVM and LVMI, adjusting for potential confounders.

Results

Among 126 participants (78% with hypertension), median age was 46 years, median eGFR 63 ml/min/1.73 m2, and median [IQR] systolic blood pressure was 125 [116–133] mmHg. Prevalence of LVH was 21.4% as defined by LVMI and was not significantly different (p = 0.8) between those with and without HTN, and was similar (21.4%) after excluding those (N = 21) with known cardiac disease. Greater TKV and lower eGFR were directly correlated with greater LVMI (p = .016 and p < .001, respectively). In multiple linear regression models accounting for potential confounders including blood pressure, greater TKV was positively associated with LVM (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \hat{\beta} $$\end{document}β^ =0.19, p = 0.04).

Conclusions

In a contemporary cohort of ADPKD patients with well-controlled blood pressure, the prevalence of LVH is high, and ADPKD severity as reflected by TKV is independently associated with greater LV mass. These results may suggest a relationship between ADPKD pathophysiology and increased LV mass.

The role of the exocyst in renal ciliogenesis, cystogenesis, tubulogenesis, and development

The exocyst is a highly conserved eight-subunit protein complex (EXOC1–8) involved in the targeting and docking of exocytic vesicles translocating from the trans-Golgi network to various sites in renal cells. EXOC5 is a central exocyst component because it connects EXOC6, bound to the vesicles exiting the trans-Golgi network via the small GTPase RAB8, to the rest of the exocyst complex at the plasma membrane. In the kidney, the exocyst complex is involved in primary ciliognesis, cystogenesis, and tubulogenesis. The exocyst, and its regulators, have also been found in urinary extracellular vesicles, and may be centrally involved in urocrine signaling and repair following acute kidney injury. The exocyst is centrally involved in the development of other organs, including the eye, ear, and heart. The exocyst is regulated by many different small GTPases of the RHO, RAL, RAB, and ARF families. The small GTPases, and their guanine nucleotide exchange factors and GTPase-activating proteins, likely give the exocyst specificity of function. The recent development of a floxed Exoc5 mouse line will aid researchers in studying the role of the exocyst in multiple cells and organ types by allowing for tissue-specific knockout, in conjunction with Cre-driver mouse lines.

Clinical characteristics of individual organ system disease in non-motile ciliopathies

Non-motile ciliopathies (disorders of the primary cilia) include autosomal dominant and recessive polycystic kidney diseases, nephronophthisis, as well as multisystem disorders Joubert, Bardet-Biedl, Alström, Meckel-Gruber, oral-facial-digital syndromes, and Jeune chondrodysplasia and other skeletal ciliopathies. Chronic progressive disease of the kidneys, liver, and retina are common features in non-motile ciliopathies. Some ciliopathies also manifest neurological, skeletal, olfactory and auditory defects. Obesity and type 2 diabetes mellitus are characteristic features of Bardet-Biedl and Alström syndromes. Overlapping clinical features and molecular heterogeneity of these ciliopathies render their diagnoses challenging. In this review, we describe the clinical characteristics of individual organ disease for each ciliopathy and provide natural history data on kidney, liver, retinal disease progression and central nervous system function.

Human pre-valvular endocardial cells derived from pluripotent stem cells recapitulate cardiac pathophysiological valvulogenesis

Genetically modified mice have advanced our understanding of valve development and disease. Yet, human pathophysiological valvulogenesis remains poorly understood. Here we report that, by combining single cell sequencing and in vivo approaches, a population of human pre-valvular endocardial cells (HPVCs) can be derived from pluripotent stem cells. HPVCs express gene patterns conforming to the E9.0 mouse atrio-ventricular canal (AVC) endocardium signature. HPVCs treated with BMP2, cultured on mouse AVC cushions, or transplanted into the AVC of embryonic mouse hearts, undergo endothelial-to-mesenchymal transition and express markers of valve interstitial cells of different valvular layers, demonstrating cell specificity. Extending this model to patient-specific induced pluripotent stem cells recapitulates features of mitral valve prolapse and identified dysregulation of the SHH pathway. Concurrently increased ECM secretion can be rescued by SHH inhibition, thus providing a putative therapeutic target. In summary, we report a human cell model of valvulogenesis that faithfully recapitulates valve disease in a dish.

There are few human models that can recapitulate valve development in vitro. Here, the authors derive human pre-valvular endocardial cells (HPVCs) from iPSCs and show they can recapitulate early valvulogenesis, and patient derived HPVCs have features of mitral valve prolapse and identified SHH dysregulation.

Risk of Ascending Aortic Aneurysm in Patients With Autosomal Dominant Polycystic Kidney Disease

In recent years, simple renal cysts have been associated with an increased risk of aortic aneurysms. There is little data regarding aortic dilation in patients with autosomal dominant polycystic kidney disease (ADPKD). The aim of this study was to compare Sinuses of Valsalva (SoV) and tubular ascending aorta diameters in ADPKD patients with matched controls. From 2008 to 2016, 61 consecutive ADPKD patients who had an echocardiogram performed in our institution were matched 1:1 with controls for sex, age, blood pressure, and β-blocker therapy use. SoV and tubular ascending aorta were measured at end-diastole, using the leading-edge to leading-edge convention. Paired t Tests were used for quantitative variables and McNemar-tests for qualitative variables. The mean age of patients was 56 ± 12 years, 54% were men, 38% received β-blockers, and mean systolic and diastolic BP were 137 ± 25 and 78 ± 19 mm Hg. SoV diameters were significantly larger in ADPKD patients than in controls (36.4 ± 4.1 vs 34.0 ± 3.7 mm, p <0.0001). The Z-scores (normalized for sex, age, and body surface area) were significantly higher in ADPKD patients, both for SoV and tubular ascending aorta. Moreover, aortic aneurysms, as defined by a Z score >2 standard deviations, were present in 27 ADPKD patients (44%) versus 9 controls (15%, p <0.001). In conclusion, there is an increased prevalence of aortic aneurysms in ADPKD patients as compared with controls matched for common confounding factors for aortic dilation.

Clinical Manifestation, Management and Prognosis of Acute Myocardial Infarction in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND/AIMS

Cardiovascular complications are the most common cause of death in individuals with autosomal dominant polycystic kidney disease (ADPKD), yet there is no substantial data concerning the clinical characteristics of acute myocardial infarction (AMI) in this population. This study thus aimed to investigate AMI in persons with ADPKD.

METHODS

A retrospective analysis of ADPKD patients admitted to our hospital over a 13 year period was conducted. Age and gender-matched control patients without ADPKD were also selected at a ratio of 1: 10.

RESULTS

A total of 52 ADPKD and 520 non-ADPKD patients were enrolled in the present study, with those in the former group exhibiting significantly poorer kidney function. The distribution of AMI types differed significantly between these two groups. The incidence of ST-segment elevation myocardial infarction (STEMI) was higher (75.0%) and the incidence of non-ST segment elevation myocardial infarction (NSTEMI) was lower (25.0%) in the ADPKD group. At the onset of AMI, sudden cardiac death (SCD) was more common in ADPKD patients (11.5% vs. 4.6%). In terms of risk factors, the occurrence of hypertension was greater in ADPKD patients (78.8% vs. 39.6%). With regard to subsequent management, ADPKD patients had a higher prevalence of triple-branch coronary lesions (21.1% vs. 11.2%), undergoing more coronary artery bypass grafting (CABG) (7.7% vs. 5.4%) and fewer percutaneous coronary interventions (PCI) (73.1% vs. 84.6%). Overall, ADPKD patients had higher rates of mortality (13.5% vs. 6.2%).

CONCLUSION

ADPKD patients with AMI suffer from more severe conditions and difficult therapies, resulting in a poorer prognosis.

Mechanotransduction Mechanisms in Mitral Valve Physiology and Disease Pathogenesis

The mitral valve exists in a mechanically demanding environment, with the stress of each cardiac cycle deforming and shearing the native fibroblasts and endothelial cells. Cells and their extracellular matrix exhibit a dynamic reciprocity in the growth and formation of tissue through mechanotransduction and continuously adapt to physical cues in their environment through gene, protein, and cytokine expression. Valve disease is the most common congenital heart defect with watchful waiting and valve replacement surgery the only treatment option. Mitral valve disease (MVD) has been linked to a variety of mechano-active genes ranging from extracellular components, mechanotransductive elements, and cytoplasmic and nuclear transcription factors. Specialized cell receptors, such as adherens junctions, cadherins, integrins, primary cilia, ion channels, caveolae, and the glycocalyx, convert mechanical cues into biochemical responses via a complex of mechanoresponsive elements, shared signaling modalities, and integrated frameworks. Understanding mechanosensing and transduction in mitral valve-specific cells may allow us to discover unique signal transduction pathways between cells and their environment, leading to cell or tissue specific mechanically targeted therapeutics for MVD.

A role for primary cilia in aortic valve development and disease

BACKGROUND

Bicuspid aortic valve (BAV) disease is the most common congenital heart defect, affecting 0.5-1.2% of the population and causing significant morbidity and mortality. Only a few genes have been identified in pedigrees, and no single gene model explains BAV inheritance, thus supporting a complex genetic network of interacting genes. However, patients with rare syndromic diseases that stem from alterations in the structure and function of primary cilia ("ciliopathies") exhibit BAV as a frequent cardiovascular finding, suggesting primary cilia may factor broadly in disease etiology.

RESULTS

Our data are the first to demonstrate that primary cilia are expressed on aortic valve mesenchymal cells during embryonic development and are lost as these cells differentiate into collagen-secreting fibroblastic-like cells. The function of primary cilia was tested by genetically ablating the critical ciliogenic gene Ift88. Loss of Ift88 resulted in abrogation of primary cilia and increased fibrogenic extracellular matrix (ECM) production. Consequentially, stratification of ECM boundaries normally present in the aortic valve were lost and a highly penetrant BAV phenotype was evident at birth.

CONCLUSIONS

Our data support cilia as a novel cellular mechanism for restraining ECM production during aortic valve development and broadly implicate these structures in the etiology of BAV disease in humans. Developmental Dynamics 246:625-634, 2017. © 2017 Wiley Periodicals, Inc.

New-onset Atrial Fibrillation is Associated With Polycystic Kidney Disease: A Nationwide Population-based Cohort Study

Cardiovascular complications remain the major problems contributing to morbidity and mortality in patients with polycystic kidney disease (PKD). Therefore, the authors hypothesized that atrial fibrillation (AF) is closely associated with PKD. The authors conducted a nationwide population-based cohort study to investigate the risk of AF in patients with PKD. Using data from inpatient claims, the authors enrolled 7203 patients aged over 20 years who were diagnosed with PKD from 1998 to 2010 with no history of AF as the PKD cohort. They randomly selected 28,739 people without PKD as controls and frequency matched them with patients with PKD according to their age, sex, and baseline comorbidity. In total, 247 PKD patients were diagnosed with AF, representing an incidence of 7.08 per 1000 person-years, whereas 807 cases of AF occurred in the comparison cohort, yielding an incidence of 4.98 per 1000 person-y, with an adjusted HR (aHR) of 1.31 (95% CI = 1.14-1.51). The risk of AF increased from an aHR of 1.59 (95% CI = 1.15-2.21) to 3.64 (95% CI = 1.93-6.85) when the number of risk factors increased from 1 to more than 5 in comparison with patients without risk factors. A remarkably high incidence rate and risk was observed in patients with PKD when multiple risk factors were combined. A high index of suspicion should be maintained when examining PKD patients with irregular betas. Early prophylactic therapy is warranted in these patients.

Use of Ultra-high Field MRI in Small Rodent Models of Polycystic Kidney Disease for In Vivo Phenotyping and Drug Monitoring

Several in vivo pre-clinical studies in Polycystic Kidney Disease (PKD) utilize orthologous rodent models to identify and study the genetic and molecular mechanisms responsible for the disease, and are very convenient for rapid drug screening and testing of promising therapies. A limiting factor in these studies is often the lack of efficient non-invasive methods for sequentially analyzing the anatomical and functional changes in the kidney. Magnetic resonance imaging (MRI) is the current gold standard imaging technique to follow autosomal dominant polycystic kidney disease (ADPKD) patients, providing excellent soft tissue contrast and anatomic detail and allowing Total Kidney Volume (TKV) measurements.A major advantage of MRI in rodent models of PKD is the possibility for in vivo imaging allowing for longitudinal studies that use the same animal and therefore reducing the total number of animals required. In this manuscript, we will focus on using Ultra-high field (UHF) MRI to non-invasively acquire in vivo images of rodent models for PKD. The main goal of this work is to introduce the use of MRI as a tool for in vivo phenotypical characterization and drug monitoring in rodent models for PKD.

[Pathophysiology, epidemiology, clinical presentation, diagnosis and treatment options for autosomal dominant polycystic kidney disease]

Autosomal dominant polycystic kidney disease (ADPKD) is the leading genetic cause of end-stage renal disease (ESRD) worldwide. Its prevalence is evaluated according to studies and population between 1/1000 and 1/4000 live births and it accounts for 6 to 8% of incident ESRD patients in developed countries. ADPKD is characterized by numerous cysts in both kidneys and various extrarenal manifestations that are detailed in this review. Clinico-radiological and genetic diagnosis are also discussed. Mutations in the PKD1 and PKD2 codifying for polycystin-1 (PC-1) and polycystin-2 (PC-2) are responsible for the 85 and 15% of ADPKD cases, respectively. In primary cilia of normal kidney epithelial cells, PC-1 and PC-2 interact forming a complex involved in flow- and cilia-dependant signalling pathways where intracellular calcium and cAMP play a central role. Alteration of these multiple signal transduction pathways leads to cystogenesis accompanied by dysregulated planar cell polarity, excessive cell proliferation and fluid secretion, and pathogenic interactions of epithelial cells with an abnormal extracellular matrix. The mass effect of expanding cyst is responsible for the decline in glomerular filtration rate that occurs late in the course of the disease. For many decades, the treatment for ADPKD aims to lessen the condition's symptoms, limit kidney damage, and prevent complications. Recently, the development of promising specific treatment raises the hope to slow the growth of cysts and delay the disease. Treatment strategies targeting cAMP signalling such as vasopressin receptor antagonists or somatostatin analogs have been tested successfully in clinical trials with relative safety. Newer treatments supported by preclinical trials will become available in the next future. Recognizing early markers of renal progression (clinical, imaging, and genetic markers) to identify high-risk patients and multidrug approaches with synergistic effects may provide new opportunities for the treatment of ADPKD.

Multiple cardiovascular manifestations in a patient with autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a systemic disorder associated with various extrarenal complications. The major cardiovascular complications of ADPKD include valvulopathies and vascular ectasia. A 64-year-old man who was diagnosed with ADPKD seven years previously was admitted to our hospital for heart failure. Pelvic computed tomography revealed multiple variable-sized cysts in both kidneys. Transthoracic echocardiography showed enlargement of the left ventricle and left atrium. Severe mitral regurgitation and moderate aortic regurgitation with annuloaortic ectasia were observed. The left main coronary artery was dilated. The patient had various cardiovascular features associated with ADPKD.

Renal transplantation in autosomal dominant polycystic kidney disease

In patients with autosomal dominant polycystic kidney disease (ADPKD) evaluated for kidney transplantation, issues related to native nephrectomy, cystic liver involvement, screening for intracranial aneurysms and living-related kidney donation deserve special consideration. Prophylactic native nephrectomy is restricted to patients with a history of cyst infection or recurrent haemorrhage or to those in whom space must be made to implant the graft. Patients with liver involvement require pretransplant imaging. Selection of patients for pretransplant screening of intracranial aneurysms should follow the general recommendations for patients with ADPKD. In living related-donor candidates aged <30 years and at-risk of ADPKD, molecular genetic testing should be carried out when ultrasonography and MRI findings are normal or equivocal. After kidney transplantation, patient and graft survival rates are excellent and the volume of native kidneys decreases. However, liver cysts continue to grow and treatment with a somatostatin analogue should be considered in patients with massive cyst involvement. Cerebrovascular events have a marginal effect on post-transplant morbidity and mortality. An increased risk of new-onset diabetes mellitus and nonmelanoma skin cancers has been reported, but several studies have challenged these findings. Finally, no data currently support the preferential use of mammalian target of rapamycin inhibitors as immunosuppressive agents in transplant recipients with ADPKD.

The TRPP subfamily and polycystin-1 proteins

It has been exciting times since the identification of polycystic kidney disease 1 (PKD1) and PKD2 as the genes mutated in autosomal dominant polycystic kidney disease (ADPKD). Biological roles of the encoded proteins polycystin-1 and TRPP2 have been deduced from phenotypes in ADPKD patients, but recent insights from vertebrate and invertebrate model organisms have significantly expanded our understanding of the physiological functions of these proteins. The identification of additional TRPP (TRPP3 and TRPP5) and polycystin-1-like proteins (PKD1L1, PKD1L2, PKD1L3, and PKDREJ) has added yet another layer of complexity to these fascinating cellular signalling units. TRPP proteins assemble with polycystin-1 family members to form receptor-channel complexes. These protein modules have important biological roles ranging from tubular morphogenesis to determination of left-right asymmetry. The founding members of the polycystin family, TRPP2 and polycystin-1, are a prime example of how studying human disease genes can provide insights into fundamental biological mechanisms using a so-called "reverse translational" approach (from bedside to bench). Here, we discuss the current literature on TRPP ion channels and polycystin-1 family proteins including expression, structure, physical interactions, physiology, and lessons from animal model systems and human disease.

Extra-renal manifestations of autosomal dominant polycystic kidney disease (ADPKD): considerations for routine screening and management

Autosomal-dominant polycystic kidney disease (ADPKD) is a systemic disease, marked by progressive increase of bilateral renal cysts, resulting in chronic kidney disease (CKD) and often leading to end-stage renal disease (ESRD). Apart from renal cysts, patients often have extra-renal disease, involving the liver, heart and vasculature. Other less common but equally important extra-renal manifestations of ADPKD include diverticular disease, hernias, male infertility and pain. Extra-renal disease burden is often asymptomatic, but may result in increased morbidity and mortality. If the disease burden is significant, screening may prove beneficial. We review the rationale for current screening recommendations and propose some guidelines for screening and management of ADPKD patients.

Pathophysiology, epidemiology, classification and treatment options for polycystic liver diseases

Polycystic liver diseases (PLD) represent a group of genetic disorders in which cysts occur in the liver (autosomal dominant polycystic liver disease) or in combination with cysts in the kidneys (autosomal dominant polycystic kidney disease). Regardless of the genetic mutations, the natural history of these disorders is alike. The natural history of PLD is characterized by a continuous increase in the volume and the number of cysts. Both genders are affected; however, women have a higher prevalence. Most patients with PLD are asymptomatic and can be managed conservatively. Severe symptoms can affect 20% of patients who develop massive hepatomegaly with compression of the surrounding organs. Rrarely, patients with PLD suffer from acute complications caused by the torsion of hepatic cysts, intraluminal cystic hemorrhage and infections. The most common methods for the diagnosis of PLD are cross sectional imaging studies. Abdominal ultrasound and computerized tomography are the two most frequently used investigations. Magnetic resonance imaging is more sensitive and specific, and it is a valuable test for patients with intravenous contrast allergies or renal dysfunction. Different treatment modalities are available to physicians caring for these patients. Medical treatment has been ineffective. Percutaneous sclerotherapy, trans-arterial embolization, cyst fenestration, hepatic resection and liver transplantation are indicated to specific groups of patients and have to be tailored according to the extent of disease. This review outlines the current knowledge of the pathophysiology, clinical course, diagnosis and treatment strategies of PLD.

Polycystin-2 mutations lead to impaired calcium cycling in the heart and predispose to dilated cardiomyopathy

Mutations in PKD1 and PKD2, the genes encoding the proteins polycystin-1 (PC1) and polycystin-2 (PC2), cause autosomal dominant polycystic kidney disease (ADPKD). Although the leading cause of mortality in ADPKD is cardiovascular disease, the relationship between these conditions remains poorly understood. PC2 is an intracellular calcium channel expressed in renal epithelial cells and in cardiomyocytes, and is thus hypothesized to modulate intracellular calcium signaling and affect cardiac function. Our first aim was to study cardiac function in a zebrafish model lacking PC2 (pkd2 mutants). Next, we aimed to explore the relevance of this zebrafish model to human ADPKD by examining the Mayo Clinic's ADPKD database for an association between ADPKD and idiopathic dilated cardiomyopathy (IDCM). Pkd2 mutant zebrafish showed low cardiac output and atrioventricular block. Isolated pkd2 mutant hearts displayed impaired intracellular calcium cycling and calcium alternans. These results indicate heart failure in the pkd2 mutants. In human ADPKD patients, we found IDCM to coexist frequently with ADPKD. This association was strongest in patients with PKD2 mutations. Our results demonstrate that PC2 modulates intracellular calcium cycling, contributing to the development of heart failure. In human subjects we found an association between ADPKD and IDCM and suggest that PKD mutations contribute to the development of heart failure.

Systematic review: the pathophysiology and management of polycystic liver disease

BACKGROUND

Polycystic liver diseases (PCLD) represent a group of genetic disorders in which cysts occur solely in the liver, or together with renal cysts. Most of the patients with PCLD are asymptomatic, however, in some patients, expansion of liver cysts causes invalidating abdominal symptoms.

AIM

To provide a systemic review on the pathophysiology and management of PCLD.

METHODS

A PubMed search was undertaken to identify relevant literature using search terms including polycystic liver disease, pathophysiology, surgical and medical management.

RESULTS

The most common complication in patients with PCLD is extensive hepatomegaly, which may lead to malnutrition and can be lethal. Conservative surgical approaches are only partially effective and do not change the natural course of the disease. Liver transplantation has been successfully performed in PCLD, however, in an era of organ shortage, medical management needs to be evaluated. A better understanding of the pathophysiology and the availability of animal models have already identified promising drugs. Abnormalities in cholangiocyte proliferation/apoptosis and enhanced fluid secretion are key factors in the pathophysiology. It has been demonstrated in rodents and in humans that somatostatin analogues diminish liver volume. The role of the inhibitors of the mammalian target of rapamycin (mTOR) in the management of PCLD is still under investigation.

CONCLUSIONS

The exact pathophysiology of polycystic liver disease still remains unclear. In symptomatic patients, none of the currently available surgical options except liver transplantation have been shown to change the natural course of the disease. The use of somatostatin analogues has been shown to diminish liver volume.

TRPP channels and polycystins

The founding member of the TRPP family, TRPP2, was identified as one of the disease genes causing autosomal dominant polycystic kidney disease (ADPKD). ADPKD is the most prevalent, potentially lethal, monogenic disorder in humans, with an average incidence of one in 400 to one in 1,000 individuals worldwide. Here we give an overview of TRPP ion channels and Polycystin-1 receptor proteins focusing on more recent studies. We include the Polycystin-1 family since these proteins are functionally linked to TRPP channels.

The underlying causes of chordae tendinae rupture: a systematic review

BACKGROUND

The underlying causes of chordae tendinae rupture (CTR) and their frequencies vary. Different publications reached conflicting conclusions due to diverse definitions, different detection measures, and morbidity trends over time.

METHODS

Systematic literature review of unselected CTR series and underlying cause frequencies reanalysis.

RESULTS

Primary CTR overall rates before and since 1985 remain considerable (52.5% vs. 51.2%), yet median decreased (35% and 14%). Sub-acute endocarditis (SBE) and rheumatic heart disease (RHD) were the most frequent causes before 1985 (54.4% and 42.1%, respectively); since 1985 SBE and RHD have dropped sharply to 37.4% and 24.8%, respectively. Since 1985, mitral valve prolapse (MVP) and myxomatous degeneration (MD) have caused 44.5% and 11.7%, respectively. All other causes were almost not evident.

CONCLUSIONS

"Primary CTR" remains significant. MD may be underestimated, as microscopic evaluation was not routinely performed. MD is probably the most frequent underlying cause given it is also the underlying cause of MVP. MVP may be overestimated due to detection criteria and misinterpretation of leaflet prolapse. SBE, frequently coexistent with other underlying causes, may be overestimated either due to detection bias or being a consequence rather than CTR cause. RHD is expected to further decline, following rheumatic fever. Previous significant underlying causes proved to be episodic if at all causative, e.g., blunt chest trauma, generalized connective tissue disorder, ischemic heart disease, and other heart and valvular diseases. CTR can occur in apparently healthy subjects having no atypical appearance and who may be unaware of carrying risk.

Extrarenal manifestations of autosomal dominant polycystic kidney disease

Although asymptomatic in most patients, extrarenal manifestations of ADPKD may become more clinically relevant with the increasing life expectancy of affected patients. They mainly encompass cysts in other organs than the kidney (liver: 94%, seminal vesicle: 40%, pancreas: 9%, arachnoid membrane: 8%, and spinal meningeal, 2%) and connective tissue abnormalities (mitral valve prolapse: 25%, intracranial aneurysms: 8%, and abdominal hernia: 10%). Their recognition may spare the patient from other, useless investigations (eg, when an arachnoid cyst is incidentally found) or lead to the implementation of prophylactic or therapeutic measures (eg, screening, sometimes followed by the treatment of an asymptomatic intracranial aneurysm in at-risk patients, or, in the presence of a severe polycystic liver disease, avoidance from estrogens and treatment aimed to slow cyst growth).