The hemodynamic effects of acute aortic regurgitation into a stiffened left ventricle resulting from chronic aortic stenosis

The hybrid (physical-computational) cardiovascular simulator to study valvular diseases

To better understand the impact of valvular heart disease (VHD) on the hemodynamics of the circulatory system, investigations can be carried out using a model of the cardiovascular system. In this study, a previously developed hybrid (hydro-numerical) simulator of the cardiovascular system (HCS) was adapted and used. In our HCS Björk-Shiley mechanical heart valves were used, playing the role of mitral and aortic ones. In order to simulate aortic stenosis (AS) and mitral regurgitation (MR), special mechanical devices have been developed and integrated with the HCS. The simulation results proved that the system works correctly. Namely, in the case of AS - the mean pulmonary arterial pressure was increased due to increased preload of the left ventricle and the decrease in right ventricular preload was caused by a decrease in systemic arterial pressure. The severity of AS was performed based on the transaortic pressure gradient as well as using the Gorlin and Aaslid equations. In the case of severe AS, when the mean gradient was above 40 mmHg, the aortic valve orifice area was 0.5 cm2, which is in line with ACC/AHA guidelines. For the case of MR - with increasing severity of MR, there was a decrease in the left ventricular pressure and an increase in left atrial pressure. Using mechanical heart valves to simulate VHD by the HCS can be a valuable tool for biomedical research, providing a safe and controlled environment to study and understand the pathophysiology of VHD.

An Unusual Case of Bicuspid Aortic Valve With Prolapse Masquerading as Cusp Perforation

We present a unique clinical scenario of a 58-year-old male with a past medical history of hypertension who initially presented with chest pain and was ruled in for non-ST elevation myocardial infarction (NSTEMI) but rapidly developed respiratory failure secondary to aortic insufficiency complicated by cardiogenic shock (CS), attributed to aortic valve prolapse. Intriguingly, the patient had a normal ECG on presentation, underscoring the dynamic nature of valvular pathology. The development of CS highlights the importance of early recognition, prompt diagnosis, and interdisciplinary management in such complex cases.

Paravalvular regurgitation after transcatheter aortic valve replacement: incidence, quantification, and prognostic impact

Transcatheter aortic valve replacement (TAVR) is the standard of care in aortic stenosis with results comparable to surgical aortic valve replacement. However, paravalvular regurgitation (PVR) is more common after TAVR. With the alteration of devices and implantation techniques, the incidence of moderate or more PVR has declined. Mild PVR is still common in around 30% of TAVR patients in low-risk trials. Progression of AS causes myocardial hypertrophy and varying degrees of diastolic dysfunction which may cause heart failure even in combination with small volumes of PVR. Any degree of PVR is associated with an increased risk of overall and cardiovascular mortality. Predictors of PVR are annular eccentricity, severe calcification of the aortic valve, bicuspid aortic valves, and type of prosthesis where balloon-expandable devices are associated with less PVR. PVR is diagnosed using echocardiography, aortic angiogram with or without videodensitometry, haemodynamic parameters, or cardiac magnetic resonance. PVR can be treated using post-dilation, interventional treatment using a vascular plug, or implantation of a second device. Successful post-dilation depends on balloon size which should at least be equal to or >95% of the mean annulus diameter. Implantation of a second device to reduce PVR is successful in ∼90% of cases, either through lengthening of the sealing skirt in case of inadequate position or through further expansion of the index device. Implantation of a vascular plug can successfully reduce PVR and reduce mortality.

Incidental Perforation of Aortic Valve Leaflet Found on Presentation of Cardiogenic Shock

Aortic regurgitation (AR) is grouped into acute or chronic AR. Acute AR, unlike chronic AR, can manifest with significant hemodynamic compromise. Acute AR is typically due to endocarditis or aortic dissection, and less commonly due to blunt trauma or iatrogenic causes. We present a patient with cardiogenic shock due to severe acute AR from anterior leaflet perforation without an identifiable rheumatologic or infectious etiology.

Heart Valve Biomechanics: The Frontiers of Modeling Modalities and the Expansive Capabilities of Ex Vivo Heart Simulation

The field of heart valve biomechanics is a rapidly expanding, highly clinically relevant area of research. While most valvular pathologies are rooted in biomechanical changes, the technologies for studying these pathologies and identifying treatments have largely been limited. Nonetheless, significant advancements are underway to better understand the biomechanics of heart valves, pathologies, and interventional therapeutics, and these advancements have largely been driven by crucial in silico, ex vivo, and in vivo modeling technologies. These modalities represent cutting-edge abilities for generating novel insights regarding native, disease, and repair physiologies, and each has unique advantages and limitations for advancing study in this field. In particular, novel ex vivo modeling technologies represent an especially promising class of translatable research that leverages the advantages from both in silico and in vivo modeling to provide deep quantitative and qualitative insights on valvular biomechanics. The frontiers of this work are being discovered by innovative research groups that have used creative, interdisciplinary approaches toward recapitulating in vivo physiology, changing the landscape of clinical understanding and practice for cardiovascular surgery and medicine.

Heart failure following transcatheter aortic valve replacement

Introduction: Over the past decade, the number of transcatheter aortic valve replacement (TAVR) procedures has increased exponentially. Despite major improvements in both device and successes, the rate of hospital readmission after TAVR remains high, with heart failure (HF) decompensation being one of the most important causes.Areas covered: This review provides an overview of the current status of HF following TAVR, including details about its incidence, clinical impact, contributing factors, and current and future treatment perspectives.Expert opinion: HF decompensation has been identified as the most common cause of rehospitalization following TAVR, and it has been associated with a negative prognosis. Multiple preexisting factors including low flow status, cardiac amyloidosis, myocardial fibrosis, multivalvular disease, pulmonary hypertension, coronary artery disease, and atrial fibrillation have been associated with an increased risk of HF events. Also, multiple post-procedural factors like the occurrence of significant paravalvular leaks, severe prosthesis-patient mismatch, and conduction disturbances have also contributed to increase this risk . Thus, reducing HF events in TAVR recipients would require a multifactorial and multidisciplinary effort including the optimization of the medical treatment and close follow-up and treatment of residual or concomitant valvular disease and conduction disturbance issues. Future studies in this challenging group of patients are warranted.

Simulation of personalised haemodynamics by various mounting positions of a prosthetic valve using computational fluid dynamics

Diseases of the cardiovascular system account for nearly 42% of all deaths in the European Union. In Germany, approximately 12,000 patients receive surgical replacement of the aortic valve due to heart valve disease alone each year. A three-dimensional (3D) numerical model based on patient-specific anatomy derived from four-dimensional (4D) magnetic resonance imaging (MRI) data was developed to investigate preoperatively the flow-induced impact of mounting positions of aortic prosthetic valves to select the best orientation for individual patients. Systematic steady-state analysis of blood flow for different rotational mounting positions of the valve is only possible using a virtual patient model. A maximum velocity of 1 m/s was used as an inlet boundary condition, because the opening angle of the valve is at its largest at this velocity. For a comparative serial examination, it is important to define the standardised general requirements to avoid impacts other than the rotated implantation of the prosthetic aortic valve. In this study, a uniform velocity profile at the inlet for the inflow of the aortic valve and the real aortic anatomy were chosen for all simulations. An iterative process, with the weighted parameters flow resistance (1), shear stress (2) and velocity (3), was necessary to determine the best rotated orientation. Blood flow was optimal at a 45° rotation from the standard implantation orientation, which will offer a supply to the coronary arteries.

Left Ventricular Diastolic Dysfunction and Transcatheter Aortic Valve Replacement Outcomes: A Review

Aortic stenosis (AS) is the most common valvular disease that can lead to increased afterload, left ventricular (LV) remodeling, and myocardial fibrosis. We reviewed the literature addressing the impact of transcatheter aortic valve replacement (TAVR) on LV remodeling and patients' outcomes by elimination of AS-related high afterload. TAVR reduces afterload and improves LV remodeling recovery. However, myocardial fibrosis may not completely reverse after the TAVR. The LV diastolic dysfunction (LVDD) induced by AS is an independent predictor of post-TAVR mortality, and mortality increases with severity of LVDD. The impact of diastolic dysfunction on patient outcomes emerges at 30 days but continues to persist during mid-term follow-up. Based on severity of the baseline LVDD, some patients may tolerate post-TAVR aortic regurgitation (AR), but even minimal post-TAVR AR in patients with severe baseline LVDD can have an additive negative impact on survival. It is crucial to consider TAVR prior to development of advanced LVDD. Appropriate device selection and deployment technique are important in improvement of TAVR outcomes via elimination of AR.

Aortic Regurgitation Generates a Kinematic Obstruction Which Hinders Left Ventricular Filling

An incompetent aortic valve (AV) results in aortic regurgitation (AR), where retrograde flow of blood into the left ventricle (LV) is observed. In this work, we parametrically characterized the detailed changes in intra-ventricular flow during diastole as a result of AR in a physiological in vitro left-heart simulator (LHS). The loss of energy within the LV as the level of AR increased was also assessed. The validated LHS consisted of an optically-clear, flexible wall LV and a modular AV holder. Two-component, planar, digital particle image velocimetry was used to visualize and quantify intra-ventricular flow. A large coherent vortical structure which engulfed the whole LV was observed under control conditions. In the cases with AR, the regurgitant jet was observed to generate a "kinematic obstruction" between the mitral valve and the LV apex, preventing the trans-mitral jet from generating a coherent vortical structure. The regurgitant jet was also observed to impinge on the inferolateral wall of the LV. Energy dissipation rate (EDR) for no, trace, mild, and moderate AR were found to be 1.15, 2.26, 3.56, and 5.99 W/m³, respectively. This study has, for the first time, performed an in vitro characterization of intra-ventricular flow in the presence of AR. Mechanistically, the formation of a "kinematic obstruction" appears to be the cause of the increased EDR (a metric quantifiable in vivo) during AR. EDR increases non-linearly with AR fraction and could potentially be used as a metric to grade severity of AR and develop clinical interventional timing strategies for patients.