Mitral valve diseases: Pathophysiology and interventions

Integrating soft robotics and computational models to study left atrial hemodynamics and device testing in sinus rhythm and atrial fibrillation

Atrial fibrillation (AF) poses significant clinical challenges due to the complex and variable geometry of the left atrial appendage (LAA), whose structure complicates the development of personalized interventions like LAA occlusion (LAAO) for stroke prevention Current reliance on animal models and cadavers for the assessment of left atrium (LA) and LAA to study AF-related disease and interventions raises reproducibility concerns, necessitating the development of high fidelity, physiologically relevant tools. To address this, we present a multimodal framework combining a soft robotic benchtop simulator, a lumped parameter model (LPM), and finite element analysis (FEA) to replicate LA function in sinus rhythm, atrial flutter, and AF. The system integrates 3D-printed, patient-specific LA geometries with soft robotic actuators to reproduce realistic wall motion and hemodynamics. A compact, magnetic resonance imaging (MRI)-compatible flow loop, driven by a soft robotic left ventricle (LV), eliminates bulky and non-physiological pulsatile pumps, allowing precise flow measurements and LAAO device testing under clinically relevant conditions. Complementary LPM and FEA models provide mechanistic insights, quantifying systemic hemodynamic changes and LA wall stress during disease and interventions. The models effectively replicate the clinical markers of atrial dysfunction and arrhythmia disorders, and their physiological accuracy is demonstrated through validation against human imaging and porcine models. The soft robotic LV's ability to drive the mock flow loop is validated in a hybrid synthetic-biological configuration within a swine circulatory system, where the soft robotic ventricle replaces native ventricular contraction to sustain systemic circulation. This scalable and versatile framework integrates experimental and computational techniques to advance cardiovascular biomechanics, supporting device development, clinical research/training, and personalized AF treatment to improve patient outcomes.

Proof of Concept: Development of a Mitral Annuloplasty Ring With Crosshatch Net

OBJECTIVE

Here we report our preclinical, proof-of-concept testing to assess the ability of a novel device to correct mitral regurgitation. The Milwaukee Heart device aims to enable any cardiac surgeon to perform high-quality mitral valve repair using a standard annuloplasty ring with a crosshatch of microporous, monofilament suture.

METHODS

Hemodynamic, echocardiographic, and videographic data were collected at baseline, following induction of mitral regurgitation, and after repair using porcine hearts in an ex vivo biosimulator model. A commercially available cardiac prosthesis assessment platform was then used to assess the hydrodynamic characteristics of the study device.

RESULTS

Porcine biosimulator pressure and flow metrics exhibited successful correction of mitral regurgitation following device implantation with similar values to baseline. Hydrodynamic results yielded pressure gradients and an effective orifice area comparable to currently approved prostheses.

CONCLUSIONS

The study device effectively reduced mitral valve regurgitation and improved hemodynamics in our preclinical model with similar biophysical metrics to currently approved devices. Future in vivo trials are needed to evaluate the efficacy, biocompatibility, and freedom from the most likely adverse events, such as device thrombosis, embolic events, and hemolysis.

Pulmonary apoplexy following severe mitral valve stenosis: A case report

Hemoptysis is a common clinical symptom in emergency patients. It is characterized by the discharge of bloody sputum, which originates from the lower respiratory tract. In the majority of cases, this event is self-limiting, and only in less than 5% of cases, it is massive. Mitral valve stenosis is an uncommon cause of hemoptysis, with a prevalence of 4.2%. In rare cases of this condition, massive and sudden hemoptysis occurs, which is called pulmonary apoplexy. Here, a 35-year-old woman with a history of mitral valve stenosis is introduced who was referred to the hospital with a complaint of massive hemoptysis and sudden shortness of breath. According to the history of mitral valve stenosis, the patient was diagnosed with pulmonary apoplexy. After treatment, both the imaging findings and the patient's symptoms resolved within a short period of time. Even though pulmonary apoplexy is often severe, it can still respond well to conservative treatments and may indicate a need for immediate attention to the stenosis of the mitral valve.

Anaesthetic considerations in Shrinking Man syndrome: two case reports

BACKGROUND

Shrinking Man syndrome (SMS) is a rare but often serious complication of dialysis-dependent end-stage renal disease, characterized by significant loss of height, bone pain, bone deformity, and skin itching. Patients with SMS always have abnormal facial changes and cardiovascular system damage (manifested by hypertension, hypotension, cardiovascular calcification, and valvular heart disease), which pose a great challenge to anaesthesiologists. The purpose of this report is to describe our anaesthetic experience regarding two patients with SMS combined with alterations of the airway and cardiovascular system.

CASE PRESENTATION

We describe two cases of SMS treated at West China Hospital, a tertiary care centre in Chengdu, China. All cases met the diagnostic criteria, which comprised 1) dialysis-dependent end-stage renal disease, 2) loss of height, and 3) bone pain and bone deformity. One patient had an anticipated difficult airway and moderate-to-severe mitral stenosis. The other patient presented with significant hypotension. Anaesthetic considerations included awake fibreoptic bronchoscopy-assisted tracheal intubation, real-time transoesophageal echocardiogram monitoring and individualized blood pressure management strategies.

CONCLUSION

This case series highlights the importance of adequate preoperative assessment and preparation, as well as individualized anaesthetic management, in patients with SMS.

Attaining competency and proficiency in minimally invasive mitral valve repair: a learning curve assessment using cumulative sum analysis

OBJECTIVE

To evaluate the learning curve of minimally invasive mitral valvuloplasty (MVP).

BACKGROUND

Minimally invasive MVP is characterized by minimal trauma, minimal bleeding, and short postoperative recovery time. The learning curve of any new procedure needs to be evaluated for learning and replication. However, minimally invasive mitral valve technique is a wide-ranging concept, no further analysis of the outcomes and learning curve of minimally invasive Mitral valvuloplasty has been performed.

METHODS

One hundred and fifty consecutive patients who underwent minimally invasive MVP alone without concurrent surgery were evaluated. Using cardiopulmonary bypass (CPB) time and aortic clamping (AC) time as evaluation variables, we visualized the learning curve for minimally invasive MVP using cumulative sum analysis. We also analyzed important postoperative variables such as postoperative drainage, duration of mechanical ventilation, ICU stay and postoperative hospital stay.

RESULTS

The slope of the fitted curve was negative after 75 procedures, and the learning curve could be crossed after the completion of the 75th procedure when AC and CPB time were used as evaluation variables. And as the number of surgical cases increased, CPB, AC, postoperative drainage, duration of mechanical ventilation, ICU stay and postoperative hospital stay all showed different degrees of decrease. The incidence of postoperative adverse events is similar to conventional Mitral valvuloplasty.

CONCLUSION

Compared to conventional MVP, minimally invasive MVP provides the same satisfactory surgical results and stabilization can be achieved gradually after completion of the 75th procedure.

Epidemiological Trends in Patients Undergoing Mitral Valve Transcatheter Edge-to-Edge Repair over the Last Decade: Functional vs. Structural Mitral Regurgitation

OBJECTIVE

We aimed to investigate the demographic, clinical and hemodynamic characteristics of patients who underwent percutaneous mitral valve (MV) repair over the last decade, as well as to determine the potential changes in trends of these parameters among patients with structural and functional MR (SMR and FMR).

METHODOLOGY

We analyzed all patients who underwent interventional MV repair in our institution between January 2010 and March 2021. Our study included both SMR and FMR patients. All data were obtained from a local registry.

RESULTS

Nine hundred and seventeen patients (357 SMR patients and 563 FMR patients) were involved in this study. We did not find significant differences in demographical, clinical and hemodynamic characteristics among SMR and FMR patients. Left ventricular remodeling and systolic dysfunction were more pronounced in FMR patients. Systemic vascular resistance was the only hemodynamic parameter that differed between SMR and FMR patients; it was higher in SMR group. An evaluation of the trend between the first and last five years of our experience revealed that the number of patients treated with this technique is constantly increasing, but that this is more pronounced in SMR patients. It was also found that the operative risk of SMR and FMR patients was significantly higher in the first five years. Additionally, our results showed change in medical therapy in MR patients over the last decade in terms of increased use of angiotensin II receptor blockers and the introduction of angiotensin receptor II blocker-neprilysin inhibitor.

CONCLUSION

SMR and FMR patients who underwent interventional MV repair have similar clinical and hemodynamic characteristics. The percentage of SMR patients increased more significantly than FMR patients over the last five years.

Outcome of mitral valve repair or replacement for non-ischemic mitral regurgitation: a systematic review and meta-analysis

Background

Mitral regurgitation (MR) is a rather common valvular heart disease. The aim of this systematic review and meta-analysis was to compare the outcomes, and complications of mitral valve (MV) replacement with surgical MV repair of non-ischemic MR (NIMR)

Methods

MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials were searched until October, 2020. Studies were eligible for inclusion if they included patients with MR and reported early (30-day or in-hospital) or late all-cause mortality. For each study, data on all-cause mortality and incidence of reoperation and operative complications in both groups were used to generate odds ratios (ORs) or hazard ratios (HRs). This study is registered with PROSPERO, CRD42018089608.

Results

The literature search yielded 4834 studies, of which 20 studies, including a total of 21,898 patients with NIMR, were included. The pooled analysis showed that lower age, less female inclusion and incident of hypertension, significantly higher rates of diabetes and atrial fibrillation in the MV replacement group than MV repair group. No significant differences in the rates of pre-operative left ventricle ejection fraction (LVEF) and heart failure were observed between groups. The number of patients in the MV repair group was lower than in the MV replacement group. We found that there were significantly increased risks of mortality associated with replacement of MR. Moreover, the rate of re-operation and post-operative MR in the MV repair group was lower than in the MV replacement group.

Conclusions

In patients with NIMR, MV repair achieves higher survival and leads to fewer complications than surgical MV replacement. In light of these results, we suggest that MV repair surgery should be a priority for NIMR patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13019-021-01563-2.