Transmembrane protein 14A protects glomerular filtration barrier integrity.

Transmembrane protein 14A (TMEM14A) is a relatively unknown protein that is now identified to be required for maintaining the integrity of the glomerular filtration barrier. It is an integral transmembrane protein of 99 amino acids with three transmembrane domains. TMEM14A has been implied to suppress Bax-mediated apoptosis in other studies. Other than that, little is currently known of its function. Here, we show that its expression is diminished before onset of proteinuria in a spontaneously proteinuric rat model. Knocking down tmem14a mRNA translation results in proteinuria in zebrafish embryos without affecting tubular reabsorption. Also, it is primarily expressed by podocytes. Lastly, an increase in glomerular TMEM14A expression is exhibited in various proteinuric renal diseases. Overall, these results suggest that TMEM14A is a novel factor in the protective mechanisms of the nephron to maintain glomerular filtration barrier integrity.

Clinical Impact of Standardized TAVR Technique and Care Pathway: Insights From the Optimize PRO Study.

BACKGROUND: Procedural success and clinical outcomes after transcatheter aortic valve replacement (TAVR) have improved, but residual aortic regurgitation (AR) and new permanent pacemaker implantation (PPI) rates remain variable because of a lack of uniform periprocedural management and implantation. OBJECTIVES: The Optimize PRO study evaluates valve performance and procedural outcomes using an "optimized" TAVR care pathway and the cusp overlap technique (COT) in patients receiving the Evolut PRO/PRO+ (Medtronic) self-expanding valves. METHODS: Optimize PRO, a nonrandomized, prospective, postmarket study conducted in the United States, Canada, Europe, Middle East, and Australia, is enrolling patients with severe symptomatic aortic stenosis and no pre-existing pacemaker. Sites follow a standardized TAVR care pathway, including early discharge and a conduction disturbance management algorithm, and transfemoral deployment using the COT. RESULTS: A total of 400 attempted implants from the United States and Canada comprised the main cohort of this second interim analysis. The mean age was 78.7 ± 6.6 years, and the mean Society of Thoracic Surgeons predictive risk of mortality was 3.0 ± 2.4. The median length of stay was 1 day. There were no instances of moderate or severe AR at discharge. At 30 days, all-cause mortality or stroke was 3.8%, all-cause mortality was 0.8%, disabling stroke was 0.7%, hospital readmission was 10.1%, and cardiovascular rehospitalization was 6.1%. The new PPI rate was 9.8%, 5.8% with 4-step COT compliance. In the multivariable model, right bundle branch block and the depth of the implant increased the risk of PPI, whereas using the 4-step COT lowered 30-day PPI. CONCLUSIONS: The use of the TAVR care pathway and COT resulted in favorable clinical outcomes with no moderate or severe AR and low PPI rates at 30 days while facilitating early discharge and reproducible outcomes across various sites and operators. (Optimize PRO; NCT04091048).

Acute Severe Aortic Regurgitation From Catastrophic Pannus Obstruction in a Patient With Mechanical Aortic Valve Replacement.

A 69-year-old woman with a mechanical aortic valve presented with decompensated heart failure. Emergent echocardiogram and fluoroscopy demonstrated acute aortic regurgitation due to a dysfunctional mechanical aortic valve and non-obstructive coronary disease. An emergent valve replacement was performed confirming a fixed-open valve with pathology demonstrating obstructive pannus formation without thrombosis or vegetation.

Mutations in the heparan sulfate backbone elongating enzymes EXT1 and EXT2 have no major effect on endothelial glycocalyx and the glomerular filtration barrier.

In this study, the effect of heterozygous germline mutations in the heparan sulfate (HS) glycosaminoglycan chain co-polymerases EXT1 and EXT2 on glomerular barrier function and the endothelial glycocalyx in humans is investigated. Heparan sulfate (HS) glycosaminoglycans are deemed essential to the glomerular filtration barrier, including the glomerular endothelial glycocalyx. Animal studies have shown that loss of HS results in a thinner glycocalyx. Also, decreased glomerular HS expression is observed in various proteinuric renal diseases in humans. A case report of a patient with an EXT1 mutation indicated that this could result in a specific renal phenotype. This patient suffered from multiple osteochondromas, an autosomal dominant disease caused by mono-allelic germline mutations in the EXT1 or EXT2 gene. These studies imply that HS is indeed essential to the glomerular filtration barrier. However, loss of HS did not lead to proteinuria in various animal models. We demonstrate that multiple osteochondroma patients do not have more microalbuminuria or altered glycocalyx properties compared to age-matched controls (n = 19). A search for all Dutch patients registered with both osteochondroma and kidney biopsy (n = 39) showed that an EXT1 or EXT2 mutation does not necessarily lead to specific glomerular morphological phenotypic changes. In conclusion, this study shows that a heterozygous mutation in the HS backbone elongating enzymes EXT1 and EXT2 in humans does not result in (micro)albuminuria, a specific renal phenotype or changes to the endothelial glycocalyx, adding to the growing knowledge on the role of EXT1 and EXT2 genes in pathophysiology.

Preventing Coronary Obstruction During Transcatheter Aortic Valve Replacement: Results From the Multicenter International BASILICA Registry.

OBJECTIVES: This study sought to determine the safety of the BASILICA (bioprosthetic or native aortic scallop intentional laceration to prevent iatrogenic coronary artery obstruction) procedure. BACKGROUND: Transcatheter aortic valve replacement causes coronary artery obstruction in 0.7% of cases, with 40% to 50% mortality. BASILICA is a procedure to prevent coronary obstruction. Safety and feasibility in a large patient cohort is lacking. METHODS: The international BASILICA registry was a retrospective, multicenter, real-world registry of patients at risk of coronary artery obstruction undergoing BASILICA and transcatheter aortic valve replacement. Valve Academic Research Consortium-2 definitions were used to adjudicate events. RESULTS: Between June 2017 and December 2020, 214 patients were included from 25 centers in North America and Europe; 72.8% had bioprosthetic aortic valves and 78.5% underwent solo BASILICA. Leaflet traversal was successful in 94.9% and leaflet laceration in 94.4%. Partial or complete coronary artery obstruction was seen in 4.7%. Procedure success, defined as successful BASILICA traversal and laceration without mortality, coronary obstruction, or emergency intervention, was achieved in 86.9%. Thirty-day mortality was 2.8% and stroke was 2.8%, with 0.5% disabling stroke. Thirty-day death and disabling stroke were seen in 3.4%. Valve Academic Research Consortium-2 composite safety was achieved in 82.8%. One-year survival was 83.9%. Outcomes were similar between solo and doppio BASILICA, between native and bioprosthetic valves, and with the use of cerebral embolic protection. CONCLUSIONS: BASILICA is safe, with low reported rates of stroke and death. BASILICA is feasible in the real-world setting, with a high procedure success rate and low rates of coronary artery obstruction.

Tip-to-Base LAMPOON for Transcatheter Mitral Valve Replacement With a Protected Mitral Annulus.

OBJECTIVES: The purpose of this study was to evaluate tip-to-base intentional laceration of the anterior mitral leaflet to prevent left ventricular outflow tract obstruction (LAMPOON) in patients undergoing transcatheter mitral valve replacement (TMVR) in annuloplasty rings or surgical mitral valves. BACKGROUND: LAMPOON is an effective adjunct to TMVR that prevents left ventricular outflow tract obstruction (LVOTO). Laceration is typically performed from the base to the tip of the anterior mitral leaflet. A modified laceration technique from leaflet tip to base may be effective in patients with a prosthesis that protects the aortomitral curtain. METHODS: This is a multicenter, 21-patient, consecutive retrospective observational cohort. Patients underwent tip-to-base LAMPOON to prevent LVOTO and leaflet overhang, or therapeutically to lacerate a long anterior mitral leaflet risking or causing LVOTO. Outcomes were compared with findings from patients in the LAMPOON investigational device exemption trial with a prior mitral annuloplasty. RESULTS: Twenty-one patients with a annuloplasty or valve prosthesis-protected mitral annulus underwent tip-to-base LAMPOON (19 preventive, 2 rescue). Leaflet laceration was successful in all and successfully prevented or treated LVOTO in all patients. No patients had significant LVOTO upon discharge. There were 2 cases of unintentional aortic valve injury (1 patient underwent emergency transcatheter aortic valve replacement and 1 patient underwent urgent surgical aortic valve replacement). In both cases, the patients had a supra-annular ring annuloplasty, and the retrograde aortic guiding catheter failed to insulate the guidewire lacerating surface from the aortic root. All patients survived to 30 days. Compared with classic retrograde LAMPOON, there was a trend toward shorter procedure time. CONCLUSIONS: Tip-to-base laceration is a simple, effective, and safe LAMPOON variant applicable to patients with an appropriately positioned mitral annular ring or bioprosthetic valve. Operators should take care to insulate the lacerating surface from adjacent structures.

Glomerular permeability is not affected by heparan sulfate glycosaminoglycan deficiency in zebrafish embryos.

Proteinuria develops when specific components in the glomerular filtration barrier have impaired function. Although the precise components involved in maintaining this barrier have not been fully identified, heparan sulfate proteoglycans are believed to play an essential role in maintaining glomerular filtration. Although in situ studies have shown that a loss of heparan sulfate glycosaminoglycans increases the permeability of the glomerular filtration barrier, recent studies using experimental models have shown that podocyte-specific deletion of heparan sulfate glycosaminoglycan assembly does not lead to proteinuria. However, tubular reabsorption of leaked proteins might have masked an increase in glomerular permeability in these models. Furthermore, not only podocytes but also glomerular endothelial cells are involved in heparan sulfate synthesis in the glomerular filtration barrier. Therefore, we investigated the effect of a global heparan sulfate glycosaminoglycan deficiency on glomerular permeability. We used a zebrafish embryo model carrying a homozygous germline mutation in the ext2 gene. Glomerular permeability was assessed with a quantitative dextran tracer injection method. In this model, we accounted for tubular reabsorption. Loss of anionic sites in the glomerular basement membrane was measured using polyethyleneimine staining. Although mutant animals had significantly fewer negatively charged areas in the glomerular basement membrane, glomerular permeability was unaffected. Moreover, heparan sulfate glycosaminoglycan-deficient embryos had morphologically intact podocyte foot processes. Glomerular filtration remains fully functional despite a global reduction of heparan sulfate.

Increased dynamin expression precedes proteinuria in glomerular disease.

Dynamin plays an essential role in maintaining the structure and function of the glomerular filtration barrier. Specifically, dynamin regulates the actin cytoskeleton and the turnover of nephrin in podocytes, and knocking down dynamin expression causes proteinuria. Moreover, promoting dynamin oligomerization with Bis-T-23 restores podocyte function and reduces proteinuria in several animal models of chronic kidney disease. Thus, dynamin is a promising therapeutic target for treating chronic kidney disease. Here, we investigated the pathophysiological role of dynamin under proteinuric circumstances in a rat model and in humans. We found that glomerular Dnm2 and Dnm1 mRNA levels are increased prior to the onset of proteinuria in a rat model of spontaneous proteinuria. Also, in zebrafish embryos, we confirm that knocking down dynamin translation results in proteinuria. Finally, we show that the glomerular expression of dynamin and cathepsin L protein is increased in several human proteinuric kidney diseases. We propose that the increased expression of glomerular dynamin reflects an exhausted attempt to maintain and/or restore integrity of the glomerular filtration barrier. These results confirm that dynamin plays an important role in maintaining the glomerular filtration barrier, and they support the notion that dynamin is a promising therapeutic target in proteinuric kidney disease. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Combined carotid endarterectomy and transcatheter aortic valve replacement: Technique and outcomes.

BACKGROUND: Stroke and transient ischemic attack after transcatheter aortic valve replacement results in significantly higher morbidity and mortality. Severe carotid artery disease may be a contributing factor to this increased risk. We report our technique and outcomes of combined carotid endarterectomy (CEA) with transcatheter aortic valve replacement (TAVR). METHODS: From March 2013 to November 2017 a total of 753 TAVRs were performed at our institution for symptomatic severe aortic stenosis. Of this group, 16 patients underwent concomitant TAVR and CEA. A retrospective review was performed to assess risk, outcomes, and short-term survival. RESULTS: Sixteen patients underwent concomitant CEA/TAVR procedures for severe carotid and severe aortic stenosis. The mean Society of Thoracic Surgeons (STS) Risk Score was 7.0 ± 4.7. All patients had severe carotid artery stenosis and aortic stenosis. Nine patients had a transfemoral TAVR approach and eight patients had a transapical TAVR approach. The mean length of stay was 6.4 ± 3.7 days. At 30 days there were no cerebrovascular events and no mortalities. CONCLUSIONS: The use of concomitant CEA and TAVR in patients with severe aortic stenosis and severe carotid stenosis can be done safely without increased risk of complications. This approach may reduce the risk of stroke associated with TAVR in appropriately selected patients.

Cystinosis (ctns) zebrafish mutant shows pronephric glomerular and tubular dysfunction.

The human ubiquitous protein cystinosin is responsible for transporting the disulphide amino acid cystine from the lysosomal compartment into the cytosol. In humans, Pathogenic mutations of CTNS lead to defective cystinosin function, intralysosomal cystine accumulation and the development of cystinosis. Kidneys are initially affected with generalized proximal tubular dysfunction (renal Fanconi syndrome), then the disease rapidly affects glomeruli and progresses towards end stage renal failure and multiple organ dysfunction. Animal models of cystinosis are limited, with only a Ctns knockout mouse reported, showing cystine accumulation and late signs of tubular dysfunction but lacking the glomerular phenotype. We established and characterized a mutant zebrafish model with a homozygous nonsense mutation (c.706 C > T; p.Q236X) in exon 8 of ctns. Cystinotic mutant larvae showed cystine accumulation, delayed development, and signs of pronephric glomerular and tubular dysfunction mimicking the early phenotype of human cystinotic patients. Furthermore, cystinotic larvae showed a significantly increased rate of apoptosis that could be ameliorated with cysteamine, the human cystine depleting therapy. Our data demonstrate that, ctns gene is essential for zebrafish pronephric podocyte and proximal tubular function and that the ctns-mutant can be used for studying the disease pathogenic mechanisms and for testing novel therapies for cystinosis.

Severe Acute Traumatic Mitral Regurgitation, Cardiogenic Shock Secondary to Embolized Polymethylmethracrylate Cement Foreign Body After a Percutaneous Vertebroplasty.

We report the case of a 61-year-old woman with acute decompensated heart failure secondary to acute traumatic mitral regurgitation, resulting from polymethylmethacrylate cement found in the left ventricle less than 24 hours after fluoroscopic percutaneous vertebroplasty. The patient had a history of ovarian cancer and had undergone treatment for symptomatic osteoporotic compression fractures of the vertebrae (T11, L1, and L3). The patient underwent a successful emergency open-heart operation, mitral valve replacement, closure of an atrial septal defect, and video-assisted removal of the cement foreign body from the left ventricle. The patient was later discharged with a good outcome.

A Review of PMMA Bone Cement and Intra-Cardiac Embolism.

Percutaneous vertebroplasty procedure is of major importance, given the significantly increasing aging population and the higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving the injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main effects of PMMA bone cement on the heart, and the extent of influence of the materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case reports.

Non-aneurysmal aberrant right subclavian artery causing dysphagia in a young girl: challenges encountered using supraclavicular approach.

Aberrant right subclavian artery is the most common anomaly of the aortic arch. Patients are often asymptomatic and discovered accidentally. Occasionally, they present with symptoms related to oesophageal or tracheal compression.A 13-year-old girl presented with dysphagia and stridor was found to have an aberrant right subclavian artery. Surgical division and reconstruction of the artery was performed initially through right supraclavicular approach. An additional left thoracotomy was performed to overcome the challenges encountered at initial operation.

Prolonged duration of transbrachial intra-aortic balloon pump as bridge to heart transplantation.

We describe a case demonstrating the quality of life (QOL) benefit and safety of using a transbrachial approach for insertion of an intra-aortic balloon pump (IABP) in a patient awaiting cardiac transplantation. A 68-year-old man with ischaemic cardiomyopathy was admitted to our cardiac intensive care unit to await the availability of a suitable donor organ for orthotopic heart transplant. An IABP was needed for haemodynamic support due to cardiogenic shock. Since the patient did not want to be committed to lying supine in bed for multiple days, as would have been the case had the IABP been placed using the conventional femoral route, we inserted a 7.5 Fr 'sheathless' IABP via the transbrachial approach. The patient's haemodynamics improved and the device was left in place for 240 h without vascular compromise. He was subsequently successfully transplanted and is doing well on follow-up.

Balloon aortic valvuloplasty for aortic stenosis using a novel percutaneous dilation catheter and power injector.

Calcific aortic stenosis is the most common valvular heart disease in the Western world. Although definitive treatment is valve replacement, many patients are not replacement candidates due to high surgical risk from older age and comorbid illness or lack of desire for a surgical or replacement procedure. Percutaneous balloon aortic valvuloplasty (BAV) is an option for palliative treatment in nonsurgical patients, although this procedure is complicated during the immediate postprocedure period by bleeding requiring transfusion for about 1 in 5 patients and subsequent restenosis. This report describes BAV using a smaller profile balloon designed to withstand higher pressures, rapidly inflated with a power injector. Twenty consecutive high-risk patients with severe aortic stenosis were treated. In all cases, New York Heart Association (NYHA) class improved from IV before BAV to I or II at 30 days follow-up. Six-month posttreatment follow-up data were available for 19 of 20 patients: 15 patients were either NYHA class I or II, 1 patient was class III, and 3 deaths occurred unrelated to aortic stenosis. One patient was lost to follow-up. Average systolic gradient peak-to-peak pressure decreased by 40.0% (range 18.0-70.0%) and mean gradient decreased by 30.0% (range 13.7-70.8%). Aortic valve area increased from 0.59 ± 0.16 cm(2) to 0.92 ± 0.23 cm(2), representing a mean increase of 30.0% (range 7.8%-58.2%). There were no significant bleeding complications. The only procedural complication was a single case of pericardial tamponade. There were no other complications during the first 24 hours post-BAV. These data support that the reported BAV technique may offer an effective alternative for patients with severe aortic stenosis who are not surgical candidates or prefer to avoid aortic valve replacement.

MRI for the diagnosis of myocardial ischemia and viability.

Assessment of myocardial ischemia and viability plays a crucial role in the clinical management of patients with coronary artery disease. Recently, cardiovascular MRI has emerged as an important noninvasive diagnostic modality in the assessment of coronary artery disease. MRI is able to evaluate both myocardial perfusion as well as myocardial contractile reserve. Because of its superior spatial resolution, integration of qualitative and quantitative methodology, and excellent reproducibility, MRI has advantages over conventional noninvasive modalities currently used in the evaluation of myocardial ischemia and viability, and may well emerge as the premier noninvasive technique in the assessment of patients with coronary artery disease. The authors review the rapidly expanding recent literature that has now established cardiovascular MRI (including dobutamine cine MRI and vasodilator perfusion MRI techniques) as an ideal choice in the evaluation of myocardial ischemia and delayed contrast-enhanced MRI and low-dose dobutamine cine MRI for evaluation of viability. Comparisons with more established techniques such as dobutamine stress echocardiography, single photon emission computed tomography perfusion imaging, and positron emission tomography are reviewed.