Degenerative Mitral Valve Research Articles

Cardiac Structural and Functional Remodeling After Transcatheter Mitral Valve in Valve Implantation: Early Changes and Prognostic Significance

BackgroundTranscatheter mitral valve-in-valve (MViV) replacement has emerged as an alternative to redo mitral valve (MV) surgery for the management of failed bioprosthetic MVs. The degree of cardiac remodeling assessed by echocardiography has been shown to have prognostic implications in degenerative mitral regurgitation patients undergoing MV surgery. The impact of transcatheter MViV in patients with degenerative bioprosthetic MV failure on cardiac remodeling and its associated prognosis remains undescribed. ObjectivesThe aim of this study is to describe the early anatomic and functional changes of the left-sided chambers and right ventricle by echocardiography posttranscatheter MViV intervention and their impact on mortality outcomes. Additionally, we sought to analyze the outcome of heart failure in bioprosthetic MV failure patients undergoing transcatheter MViV replacement. MethodsWe analyzed consecutive patients undergoing MViV intervention for symptomatic bioprosthetic MV failure. Echocardiograms before intervention and within 100 days postintervention were analyzed. A chart review was performed to obtain baseline characteristics, follow-up visits, 30-day heart failure and 1-year all-cause mortality outcomes. ResultsA total of 62 patients (mean age 69 ± 13 years, 61% male) were included in the study. Most patients were undergoing MViV intervention for prosthetic mitral stenosis n = 48 (77.4%) and the rest for mitral regurgitation or mixed disease. Compared with baseline, significant reductions were observed in median left atrial volume (LAV; 103 [81–129] ml vs. 95.2 [74.5–117.5] ml, p < 0.01) and mean (SD) left atrial conduit strain (9.1% ± 5.2% vs. 10.8% ± 4.8%, p = 0.039) within 100 days postintervention. Early reduction in right ventricular free wall global longitudinal strain and fractional area change also occurred postintervention. No significant change in left ventricular chamber dimensions or ejection fraction was observed. During the 1-year follow up period, 5 (8%) patients died. While baseline LAV was not associated with 1-year all-cause mortality (OR 0.98 CI 0.95–1.01; p = 0.27), a change in LAV in the follow up period was associated with all-cause mortality at 1 year (OR 1.06 CI 1.01–1.12; p = 0.023). At 30 days postintervention, 65% of patients had an improvement in their New York Heart Association functional class. ConclusionIn this retrospective study of patients undergoing transcatheter MViV intervention for failed bioprosthetic MVs, early reverse remodeling of the left atrium occurs within 100 days postintervention and reduction in LAV is associated with reduced all-cause mortality at 1 year. In addition, there is significant improvement in heart failure symptoms at 30 days following intervention but further investigation into the longitudinal remodeling changes and long-term outcomes is needed.

Self-Reported Utilization of International Guidelines for Staging Dogs with Myxomatous Mitral Valve Degeneration: A Survey among Veterinary Practitioners.

ACVIM developed and published guidelines for staging myxomatous mitral valve degeneration in dogs in 2009. An updated version was published in 2019. The present study aimed to investigate whether these guidelines are actually used by the intended public more than a decade after their first publication. An online survey was distributed among Dutch and Belgian veterinarians through online channels and mailing lists. Of the 524 responses, only 363 complete surveys were analyzed. The ACVIM guidelines are used by 60% of the respondents. Veterinarians find it more difficult to differentiate stage B1 from B2 in asymptomatic dogs compared to diagnosing stage C. Three-quarters of the respondents would recommend echocardiography for an incidentally detected new murmur with an intensity of 3 out of 6 in an adult dog. Two-thirds of the respondents find coughing a convincing finding for stage C disease. Close to half of the respondents associate a horizontal, dull percussion line with pulmonary edema. For confirming cardiogenic pulmonary edema, 98% of the respondents used thoracic radiographs. Veterinary practitioners might not have the expected training and equipment to be able to apply the guidelines in their practices, especially in the differentiation of stage B1 from stage B2.

Repair surgical techniques in degenerative cardiac valve disease

Background: Re-evaluation of reconstructive possibilities in the correction of degenerative mitral valve disease is of great clinical necessity nowadays. Material and methods: Analyzing the nature of the pathologies that determined the development mechanism of valve insufficiency, 136 cases of anterior cusp prolapse and 152 cases of posterior cusp prolapse were determined. Results: Cord rupture was established in 79 (58.9%) patients, cusp defects (”Cleft”) were appreciated in positions A1, A2, A3 – 15 cases (5.9%) and in P1, P2, P3 – in 92 (86.6%) cases. The surgical techniques performed were separated into: (1) resection – for the anterior and posterior cusps – 45 cases and accompanied by the slide – in 30 cases; (2) with Gore-Tex neo-chordal implantation – 115 cases, with cord transfer – 30; (3) Cusp enlargement with autologous pericardium – 5 cases, Alfieri procedure – 8. Implantation of a support ring required 130 (97.0%) patients. The correction of the associated valve disease required 125 patients (De Vega – 89.1%, ring – 8). Coronary bypass was required – 16 patients. There were no postoperative fatal cases. Conclusions: Based on the data obtained, reconstructive repair surgery can be can recommend for valves of degenerative, post-traumatic, ischemic, post-endocardial etiology as effective and sustainable techniques over time, being a superior alternative to replacement with prosthetic valves.

Indicators for pulmonary hypertension in dogs with degenerative mitral valve disease.

Pulmonary hypertension (PH) is a common complication of degenerative mitral valve disease (DMVD) in dogs. This study aimed to determine PH indicators in dogs with stage C DMVD through thoracic radiography and M-mode and 2-dimensional echocardiography. A retrospective study of 133 dogs with DMVD stage C was conducted. The patients were divided into two groups: DMVD and DMVD with PH. Characteristics, thoracic radiographic findings, and echocardiographic variables were recorded for analysis. Pulmonary hypertension was diagnosed in 56 dogs, with a prevalence of 42.1%. Univariable logistic regression analysis revealed associations among PH and right-sided heart enlargement, pulmonary artery enlargement, left ventricular size, and percent fractional shortening. Multivariable logistic regression analysis demonstrated that pulmonary artery enlargement (odds ratio [OR]: 5.96; 95% confidence interval [CI]: 1.45-24.54; p = 0.014) and decreased left ventricular size (OR: 0.02; 95%CI: 0.003-0.13; p = 0.001) were significantly associated with PH. The accuracy of predicting PH in dogs at DMVD stage C using pulmonary artery enlargement combined with decreased left ventricular size was moderate (area under the curve [AUC] 0.77; 95%CI: 0.68-0.86). Pulmonary hypertension is common in dogs with DMVD stage C. The presence of pulmonary artery enlargement assessed by radiography and decreased left ventricular size assessed by echocardiography, were associated with PH and may serve as predictors of PH in DMVD stage C.

Alerting trends in epidemiology for non-rheumatic degenerative mitral valve disease, 1990–2019: An age-period-cohort analysis for the Global Burden of Disease Study 2019

BackgroundThe global and national burden of rheumatic mitral valve disease (MVD) has been well studied and estimated before. However, little is known about non-rheumatic degenerative MVD. Therefore, this study aimed to assess the trends in non-rheumatic degenerative MVD (NRDMVD) epidemiology, with an emphasis on NRDMVD mortality, leading risk factors, and their associations with age, period, and birth cohort. MethodsUsing the data derived from the Global Burden of Disease Study 2019, including prevalence, mortality, and disability-adjusted life years, we analyzed the burden of NRDMVD and the detailed trends of NRDMVD mortality over the past 30 years in 204 countries and territories by implementing the age-period-cohort framework. ResultsGlobally, the number of deaths due to NRDMVD increased from 5695.89 (95% uncertainty interval [UI]: 5405.19 to 5895.4) × 1000 in 1990 to 9137.79 (95% UI: 8395.68 to 9743.55) × 1000 in 2019. The all-age mortality rate increased from 106.47 (95% UI: 101.03 to 110.2) per 100,000 to 118.1 (95% UI: 108.51 to 125.93) per 100,000, whereas the age-standardized mortality rate decreased from 170.45 (95% UI: 159.61 to 176.94) per 100,000 to 117.95 (95% UI: 107.83 to 125.92) per 100,000. The estimated net drift of mortality per year was −1.1% (95% confidence interval: −1.17 to −1.04). The risk of death due to NRDMVD increased with age, reaching its peak after 85 years old globally. Despite female patients being associated with lower local drift than male patients, no significant gender differences were observed in the age effect across countries and regions for all sociodemographic index (SDI) levels, except low-SDI regions. ConclusionsWe estimated the global disease prevalence of and mortality due to NRDMVD over approximately a 30-year period. The health-related burden of NRDMVD has declined worldwide; however, the condition persisted in low-SDI regions. Moreover, higher attention should be paid to female patients.

Sex-Based Differences in Early Outcomes Following Mitral Valve Surgery for Degenerative Disease

Objectives: To determine whether sex-based differences exist following surgery for degenerative mitral valve disease. Methods: Using a national database, we analysed data on mitral valve surgery for degenerative disease (n = 22,658) between January 2000 and March 2019 in the UK. We split the cohort into men (n = 14,681) and women (n = 7977) and compared background characteristics, intraoperative variables and early postoperative outcomes. Our primary outcome was hospital mortality; secondary outcomes included re-exploration for bleeding, prolonged admission (&gt;10 days) and mitral replacement. We used binary logistic regression models for all outcomes, with multiplicative interaction terms to determine the nature of any differences. Results: Women presented older (70 ± 11 years vs. 67 ± 11 years, p &lt; 0.001) with worse symptom profiles (New York Heart Association Class III–IV 57% vs. 44%, p &lt; 0.001). They had higher rates of preoperative atrial fibrillation (39% vs. 35%, p &lt; 0.001) and tricuspid disease requiring surgery (21% vs. 15%, p &lt; 0.001). They had lower repair rates (66% vs. 76%, p &lt; 0.001), higher mortality (3% vs. 2%, p &lt; 0.001) and were more likely to have a prolonged admission (48% vs. 40%, p &lt; 0.001). Female sex was an independent predictor of mortality (odds ratio (OR): 1.52, 95% CI: 1.21–1.90, p &lt; 0.001). Age and Canadian Cardiovascular Society (CCS) score showed significant interactions with sex. The relationship between advancing age and mortality was found to be more pronounced in women. Conclusions: (1) Female sex is an independent predictor of hospital mortality, prolonged hospital admission and mitral valve replacement. (2) The relationship between female sex and mortality is exacerbated by worsening CCS score and advancing age. (3) Women have significantly lower repair rates.

Impact of a combination of pimobendan, furosemide, and enalapril on heart rate variability in naturally occurring, symptomatic, myxomatous mitral valve degeneration dogs

BackgroundPimobendan, diuretics, and an angiotensin-converting enzyme inhibitor (ACEi) are widely used for the management of chronic valvular heart disease in dogs; however, the effects of that combination on heart rate variability (HRV) are unknown. The purpose of this study was to assess the HRV of symptomatic myxomatous mitral valve degeneration (MMVD) dogs in response to therapy with a combination of pimobendan, diuretics, and ACEi.ResultsMMVD stage C (n = 17) dogs were enrolled and a 1-hour Holter recording together with echocardiography, blood pressure measurement, and blood chemistry profiles were obtained before and 1, 3, and 6 months after oral treatment with pimobendan (0.25 mg/kg), enalapril (0.5 mg/kg), and furosemide (2 mg/kg) twice daily. The results revealed that MMVD stage C dogs at the baseline had lower values of time-domain indices, low frequency (LF), high frequency (HF), and total power, as well as higher value of LF/HF. Triple therapy significantly increases these parameters in MMVD stage C dogs (P < 0.05). A positive moderate correlation was observed between time domain parameters and a left ventricular internal diastole diameter normalized to body weight (P < 0.05).ConclusionsIt can be concluded that MMVD stage C dogs possess low HRV due to either the withdrawal of parasympathetic tone or enhanced sympathetic activation, and a combination therapy was shown to enhance cardiac autonomic modulation inferred from the increased heart rate variability. Therefore, a combination therapy may be useful for restoring normal autonomic nervous system activity in dogs with MMVD stage C.

Closed-chest robotic repair of mitral prolapse. Surgical technique and early results.

Robotic mitral repair is generally performed with four intercostal trocars and a minithoracotomy. We describe our technique and results with a totally-thoracoscopic closed chest approach using a 12 mm valveless trocar as "working port", without a minithoracotomy. We compared our results with this technique with a control group of robotic mitral repairs performed earlier with a minithoracotomy. Review of all patients with degenerative mitral valve disease who underwent robotic mitral valve repair surgery since December 2019 (n = 110). Patients with concomitant procedures (n = 8) were excluded. The remaining 102 patients were divided in two groups, depending on the approach used, minithoracotomy (n = 63) and totally thoracoscopic (n = 39). There were no significant differences between groups regarding preoperative characteristics. All procedures were completed robotically as planned, and repair rate was 100%. The minithoracotomy group showed a higher percentage of leaflet resections (17.9% vs. 38.7%; p = 0.03). All surgical times were significatively reduced in the totally thoracoscopic group: Cardiopulmonary bypass (97 vs. 115 min, p = 0.0008), ischemic time (67 vs. 80 min, p = 0.0013) and total surgical time (185 vs. 225 min; p < 0.00001). There were no differences in ICU length of stay (1 day, p = 0.07) but hospital length of stay was shorter in the totally thoracoscopic group (4 days; p = 0.0001). Postoperative complications were similar between groups. MR at discharge was mild or less in all cases. Robotic mitral repair for degenerative disease can be safely performed as a closed-chest procedure, using a 12 mm trocar as "working port" and avoiding the need for a minithoracotomy. This approach does not seem to negatively affect the quality of the procedure by any measure, providing similar excellent clinical outcomes and repair rate. All surgical times were shorter in the closed-chest group.

Discussion to: Repeat crossclamp after failed initial degenerative mitral valve repair is safe and successful

Discussion to: Repeat crossclamp after failed initial degenerative mitral valve repair is safe and successful

Repeat crossclamp after failed initial degenerative mitral valve repair is safe and successful

ObjectiveSurgical risk and long-term outcomes when re-crossclamp is required during degenerative mitral valve repair are unknown. We examined the outcomes of patients who required re-crossclamp for mitral valve reintervention. MethodsAdults undergoing mitral valve repair for degenerative mitral valve disease at a single center from 2007 to 2021 who required more than 1 crossclamp for mitral valve reintervention were included. Outcomes including major morbidity and 30-day mortality were collected. Kaplan–Meier analysis characterized survival and freedom from recurrent mitral regurgitation. ResultsA total of 69 patients required re-crossclamp for mitral valve reintervention. Of those, 72% (n = 50) underwent successful re-repair and the remaining underwent mitral valve replacement (28%, n = 19). Major morbidity occurred in 23% (n = 16). There was no 30-day mortality, and median long-term survival was 10.9 years for those undergoing re-repair and 7.2 years for those undergoing replacement (P = .79). Midterm echocardiography follow-up was available for 67% (33/50) of patients who were successfully re-repaired with a median follow-up of 20 (interquartile range, 7-37) months. At late follow-up, 90% of patients had mild or less mitral regurgitation. Of those re-repaired, 2 patients later required mitral valve reintervention. ConclusionsPatients requiring re-crossclamp for residual mitral regurgitation had low perioperative morbidity and no mortality. Most patients underwent successful re-repair (vs mitral valve replacement) with excellent valve function and long-term survival. In the event of unsatisfactory repair at the time of mitral valve repair, attempt at re-repair is safe and successful with the appropriate valvar anatomy.

Use of serum osmolality to identify heart disease stage in dogs and relationship to mathematical chloride correction.

Heart failure-associated hypochloremia can be depletional from diuretics or dilutional from water retention. Serum osmolality reflects water balance but has not been evaluated in dogs with heart disease. To determine if serum osmolality is related to heart disease stage and amount of mathematical correction of serum chloride (Cl- ) concentrations in healthy dogs and dogs with myxomatous mitral valve degeneration (MMVD). Seventy-seven dogs (20 healthy, 25 Stage B MMVD, 32 Stage C/D MMVD). Serum Cl- concentrations were mathematically corrected. Osmolality was calculated (calOsm) and directly measured by freezing point depression (dmOsm) and compared by Bland-Altman analysis. Biochemical variables and osmolality were compared among healthy, Stage B, and Stage C/D dogs. Correlations were explored between osmolality and biochemical variables. Median and range are presented. P < .05 was considered significant. The calOsm was different among groups (P = .003), with Stage B (310 mOsm/kg; 306, 316) and C/D dogs (312 mOsm/kg; 308, 319) having higher calOsm than healthy dogs (305 mOsm/kg; 302, 308). Osmolality methods were moderately correlated (P < .0001, rs = .46) but with proportional bias and poor agreement. The amount of Cl- correction was negatively correlated with calOsm (P < .0001, rs = -.78) and dmOsm (P = .004, rs = -.33). Serum bicarbonate concentration was negatively correlated with Cl- (P < .0001, rs = -.67). Dogs with Stage B and Stage C/D heart disease had higher calOsm than healthy dogs. Osmolality was inversely related to the amount of Cl- correction, which supports its use in assessing relative body water content. Poor agreement between calOsm and dmOsm prevents methodological interchange.

Global, regional, and national incidence, mortality, and disability-adjusted life years of non-rheumatic valvular heart disease and trend analysis from 1990 to 2019: Results from the Global Burden of Disease study 2019.

In the context of the population growing and aging worldwide, the incidence of non-rheumatic valvular heart disease increased rapidly. This study aimed to describe the burden of non-rheumatic valvular heart disease, providing an up-to-date and comprehensive analysis on the global and regional levels and time trends from 1900 to 2019. The Global Burden of Disease 2019 was used to obtain data for this analysis. Non-rheumatic valvular heart disease in the Global Burden of Disease study includes both non-rheumatic calcific aortic valve disease and non-rheumatic degenerative mitral valve disease. The incidence, mortality, and disability-adjusted life year in 204 countries from 1990 to 2019 were analyzed by location, year, sex, age, and socio-demographic index. Estimated annual percentage change was calculated to represent the temporal trends from 1990 to 2019. Spearman's rank order correlation was used to determine the correlation between socio-demographic index and the incidence and burden of non-rheumatic valvular heart disease. Globally, there were 1.65 million (95% uncertainty interval, 1.56-1.76 million) incident cases, 0.16 million (95% uncertainty interval, 0.14-0.18 million) death cases, and 2.79 million (95% uncertainty interval, 2.52-3.31 million) disability-adjusted life years of non-rheumatic valvular heart disease. Compared with 1990, the number of incident cases, death cases, and disability-adjusted life years in 2019 increased by 104.58%, 210.60%, and 167.62%, respectively, the age-standardized incidence rate (estimated annual percentage change, 0.39; 95% confidence interval, 0.29 to 0.49) increased due to population growth, and the age-standardized death rates (estimated annual percentage change, -0.32; 95% confidence interval, -0.39 to -0.25) and age-standardized disability-adjusted life year rate (estimated annual percentage change, -0.81; 95% confidence interval, -0.87 to -0.74) decreased during this period. Regarding the socio-demographic index, the highest age-standardized incidence, death, and disability-adjusted life year rates of non-rheumatic valvular heart disease were found in high-socio-demographic index countries in 2019. Meantime, the age-standardized incidence rate remained increased from 1990 to 2019, while significant decreases were found in the age-standardized death rate and age-standardized disability-adjusted life year rate. Females have higher age-standardized incidence rate, while higher age-standardized death rate and age-standardized disability-adjusted life year rate belong to males globally during the period of 1990-2019. Increasing trends were observed for both incidence, death, and disability-adjusted life year rates with age. High systolic blood pressure was the leading cause for non-rheumatic valvular heart disease across all ages. From 1990 to 2019, the age-standardized incidence rate of non-rheumatic valvular heart disease remained increased, while age-standardized death rate and age-standardized disability-adjusted life year rate decreased, resulting from the growing population worldwide and improving medical resources. The aged, who has high systolic blood pressure and diet high in sodium, should pay more attention to, especially in high-socio-demographic index regions. With the population aging, the number of patients who require heart valve replacement is estimated to increase significantly in the future. Effective measures are warranted to control and treat the incidence and burden of non-rheumatic valvular heart disease.

Evaluation of antioxidant status and lipid peroxidation in dogs with myxomatous mitral valve degeneration stage B1.

Myxomatous mitral valve degeneration (MMVD) is the most common naturally occurring heart disease in dogs. There is a lack of data on antioxidant status and oxidative damage in dogs with MMVD stage B1 according to the American College of Veterinary Internal Medicine (ACVIM B1). The aim of this study was to investigate antioxidant status (plasma vitamin E, lipid-standardized vitamin E (LS-VitE), antioxidant capacity of lipid-(ACL) and water-soluble antioxidants, whole blood glutathione peroxidase and erythrocyte superoxide dismutase), and lipid peroxidation [malondialdehyde (MDA)] in dogs with MMVD ACVIM B1. Serum cholesterol and triglyceride concentrations were measured to calculate LS-VitE. Fourteen dogs with MMVD ACVIM B1 and 12 control dogs were included in the study. Dogs with MMVD had significantly higher vitamin E, ACL, MDA, and cholesterol concentrations and significantly higher LS-VitE values than control dogs. No significant correlations between MDA and antioxidant parameters were determined in either group. In conclusion, oxidative damage to lipids is already present and the antioxidant status is altered but not depleted in dogs with MMVD ACVIM B1. The antioxidant response to increased oxidative damage consists mainly of the activation of fat-soluble antioxidants. Further research is needed to evaluate the efficacy and targets of early antioxidant supplementation to prevent or ameliorate oxidative stress and mitigate disease progression in dogs with early-stage MMVD.

Routine chordal transposition during degenerative mitral valve repair to prevent systolic anterior leaflet motion

Routine chordal transposition during degenerative mitral valve repair to prevent systolic anterior leaflet motion

The Thoracic Inlet Length as a Reference Point to Radiographically Assess Cardiac Enlargement in Dogs with Myxomatous Mitral Valve Disease.

The diagnostic value of the vertebral heart size (VHS) in dogs with mitral valve degeneration (MVD) is compromised when middle thoracic vertebral anomalies are present. The objective of this study was to assess the use of the thoracic inlet heart score (TIHS) to identify left heart enlargement (LHE) secondary to MVD. The cardiac silhouette of 50 clinically healthy dogs and 106 MVD dogs in different stages was assessed on a right lateral chest radiograph. The TIHS and VHS value were calculated for each patient and compared. The TIHS was significantly different between the control dogs and the dogs with MMVD, increasing with disease stage, control 2.91 ± 0.23, Stage B1 2.98 ± 0.36, B2 3.25 ± 0.34, and C 3.53 ± 0.36, p < 0.05. A THIS ≥3.3 showed 69% sensitivity and 81% specificity to identify LHE. The TIHS showed moderate correlation with the VHS, LA/Ao, and LVIDDN 0.59, 0.42, and 0.62, respectively. The intraobserver and interobserver agreement were almost perfect, 0.96, and substantial, 0.73. The TIHS method can be used to identify LHE secondary to MMVD on dogs' thoracic radiographs.

Mitral Annular Disjunction: A Scoping Review.

Mitral annular disjunction (MAD) is the atrial displacement of the mitral valve (MV) hinge point, especially along the posterior mitral leaflet, which leads to inhomogeneous blood flow into the left ventricle, causing chronic fibrotic changes, malignant arrhythmias, and even sudden cardiac arrest. Some studies suggest that MAD is a part of normal heart morphology; however, the origin is still controversial. MAD commonly occurs with MV prolapse and myxomatous degenerative MV disease. In almost 20% of cases, MAD can occur independently as well. The prevalence of MAD in normal hearts varies from 8.6% to 96%, depending on the imaging modality and the cutoff used to define MAD. Transthoracic echocardiography is often the initial screening test, but the low sensitivity of transthoracic echocardiography to identify MAD makes it easy to miss the diagnosis altogether. More advanced imaging, especially cardiac MRI, is the gold standard for diagnosing MAD and risk stratification. MAD is an independent predictor of malignant arrhythmia. Among patients with MAD, risk stratification is based on the age at diagnosis, previous syncopal attacks, premature ventricular contractions, papillary muscle fibrosis, and longitudinal disjunction distance. Most asymptomatic patients are managed conservatively; however, radiofrequency ablation should be considered in patients with high-risk or symptomatic MAD due to the risk of ventricular arrhythmias and sudden cardiac death.

Fatal cerebrovascular accident in a captive red panda (Ailurus fulgens fulgens) with concurrent amdoparvovirus infection

We report the pathological and molecular findings in an adult male Himalayan red panda (Ailurus fulgens fulgens) whose death was attributed to parenchymal brain haemorrhage (PBH) of the thalamus. Post-mortem examination revealed severe, acute PBH and intraventricular haemorrhage with major involvement of the thalamus, as well as scattered chronic microinfarctions. Vascular disease in the brain and other organs was suggestive of systemic hypertension. Histological lesions included arteriolar hyalinosis and varying degrees of arteriosclerosis, arterial tunica media hypertrophy and hyperplasia and infiltration of arterial walls by lipid-laden macrophages. Other relevant findings included marked myocardial fibrosis, lymphoplasmacytic tubulointerstitial nephritis, lymphoplasmacytic meningoencephalitis and chronic mitral valve degeneration. The changes in the cerebral vasculature were consistent with hypertensive encephalopathy and a cerebrovascular accident, specifically PBH, which has not been previously reported in this species. Additionally, polymerase chain reaction analysis for red panda amdoparvovirus (RPAV) was positive in the brain and kidneys. Preceded by hypertensive vascular changes and brain microinfarctions, sudden death in this animal likely resulted from fatal PBH with intraventricular haemorrhage. The clinicopathological role of RPAV infection is unknown in this case, although its contribution to the chronic renal disease is considered possible in the context of our current understanding of RPAV-associated pathology.

Outra falha de bioprótese valvar cirúrgica: uma segunda solução transcateter valve-in-valve

Transcatheter mitral valve-in-valve replacement has recently emerged as an increasingly common alternative for high surgical risk patients. We report a case of a successful transseptal transcatheter mitral valve-in-valve replacement for the treatment of a bioprosthetic mitral valve degeneration and severe regurgitation, in an 86-year-old patient who had undergone transcatheter aortic valve-in-valve procedure 6 years ago. This case emphasizes the crucial role of a careful preoperative assessment using multimodality imaging to plan the procedure, in a patient with higher risk of left ventricular outflow obstruction due to the previous transcatheter aortic valve-in- valve procedure.

A Novel Standardized Method for Aiding to Determine Left Atrial Enlargement on Lateral Thoracic Radiographs in Dogs.

Left atrial enlargement indicates severe cardiac disease. Although the gold standard for determining left atrial size is echocardiography, many veterinary practices lack the necessary equipment and expertise. Therefore, thoracic radiography is often used to differentiate cardiogenic pulmonary edema from primary respiratory diseases and to facilitate distinguishing dogs with stage B1 and B2 mitral valve degeneration. The goal was to test a new standardized method for identifying radiographic left atrial enlargement. On a lateral radiograph, a straight line was drawn from the dorsal border of the tracheal bifurcation to the crossing point of the dorsal border of the caudal vena cava and the most cranial crus of the diaphragm. If a part of the left atrium extended this line dorsally, it was considered enlarged. Echocardiographic left atrial to aortic ratio (LA:Ao) was used as a reference. Thirty-nine observers with various levels of experience evaluated 90 radiographs, first subjectively, then applying the new method. The new method moderately correlated with LA:Ao (r = 0.56-0.66) in all groups. The diagnostic accuracy (72-74%) of the subjective assessment and the new method showed no difference. Though the new method was not superior to subjective assessment, it may facilitate learning and subjective interpretation.

Mechanical behavior and collagen structure of degenerative mitral valve leaflets and a finite element model of primary mitral regurgitation.

Degenerative mitral valve disease is the main cause of primary mitral regurgitation with two phenotypes: fibroelastic deficiency (FED) often with localized myxomatous degeneration and diffuse myxomatous degeneration or Barlow's disease. Myxomatous degeneration disrupts the microstructure of the mitral valve leaflets, particularly the collagen fibers, which affects the mechanical behavior of the leaflets. The present study uses biaxial mechanical tests and second harmonic generation microscopy to examine the mechanical behavior of Barlow and FED tissue. Three tissue samples were harvested from a FED patient and one sample is from a Barlow patient. Then we use an appropriate constitutive model by excluding the collagen fibers under compression. Finally, we built an FE model based on the echocardiography of patients diagnosed with FED and Barlow and the characterized material model and collagen fiber orientation. The Barlow sample and the FED sample from the most affected segment showed different mechanical behavior and collagen structure compared to the other two FED samples. The FE model showed very good agreement with echocardiography with 2.02±1.8mm and 1.05±0.79mm point-to-mesh distance errors for Barlow and FED patients, respectively. It has also been shown that the exclusion of collagen fibers under compression provides versatility for the material model; it behaves stiff in the belly region, preventing excessive bulging, while it behaves very softly in the commissures to facilitate folding. STATEMENT OF SIGNIFICANCE: This study quantifies for the first time the collagen microstructure and mechanical behavior of degenerative mitral valve (DMV) leaflets. These data will then be used for the first disease-specific finite element (FE) model of DMV. While current surgical repair of DMV is based on surgical experience, FE modeling has the potential to support decision-making and make outcomes predictable. We adopt a constitutive model to exclude collagen fiber under compressions, an important consideration when modeling the mitral valve, where the leaflets are folded to ensure complete closure. The results of this study provide essential data for understanding the relationship between collagen microstructure and degenerative mitral valve mechanics.