Efficacy of catheter-based drug delivery in a hybrid in vitro model of cardiac microvascular obstruction with porcine microthrombi.

Microvascular obstruction (MVO) often occurs in ST-elevation myocardial infarction (STEMI) patients after percutaneous coronary intervention (PCI). Diagnosis and treatment of MVO lack appropriate and established procedures. This study focused on two major points by using an in vitro multiscale flow model, which comprised an aortic root model with physiological blood flow and a microfluidic model of the microcirculation with vessel diameters down to 50 µm. First, the influence of porcine microthrombi (MT), injected into the fluidic microchip, on perfusion was investigated. We found that only 43% of all injected MT were fully occlusive. Second, it could also be shown that the maximal concentration of a dye (representing therapeutic agent) during intracoronary infusion could be increased on average by 58%, when proximally occluding the coronary artery by a balloon during drug infusion. The obtained results and insights enhance the understanding of perfusion in MVO-affected microcirculation and could lead to improved treatment methods for MVO patients.

First Report of Evolut Pro+ Transcatheter Aortic Valve-in-Valve in a Degenerated Lotus Valve.

The increasing use of transcatheter aortic valves in patients with aortic stenosis has led to a higher number of valve-in-valve procedures due to gradual valve degeneration. We present a case of a 72-year-old woman who received transcatheter aortic valve implantation (TAVI) using a Lotus valve due to severe aortic stenosis, which showed valve degeneration several years after the initial procedure. After heart-team discussion, TAVI-in-TAVI was planned using an Evolut pro+ valve, which allowed for full coverage of the Lotus valve and maintenance of coronary flow, resulting in a well-functioning valve with no regurgitation and normal performance. Despite high-risk anatomic features, valve-in-valve using an Evolut pro+ in a degenerated Lotus valve is feasible and overcomes pitfalls such as entanglement or coronary obstruction.

Incidence and Outcomes of Valve-in-Valve Transcatheter Aortic Valve Implantation in Failed Bioprosthetic Valves.

INTRODUCTION: Transcatheter aortic valve replacement (TAVR) has become a widely used, comparably efficient and safe alternative to surgical aortic valve replacement (SAVR). Its utilization continues to grow, especially among younger patients. Despite improvements in durability, degeneration and subsequent re-interventions of failed prosthetic valves are still common. Even though valve-in-valve procedures have become more frequent, little is known about the trends over time or about clinical and echocardiographic long-term outcomes. MATERIALS AND METHODS: Patients who underwent a valve-in-valve procedure between December 2011 and December 2022 in a large tertiary university hospital were analyzed. Primary outcomes were defined as procedural and device successes as well as event-free survival. Secondary analyses between subsets of patients divided by index valve and date of procedure were performed. RESULTS: Among 1407 procedures, 58 (4%) were valve-in-valve interventions, with an increased frequency observed over time. Overall, technical success was achieved in 88% and device success in 85% of patients. Complications were predominantly minor, with similar success rates among TAVR-in-SAVR (TiSAVR) and TAVR-in-TAVR (TiTAVR). Notably, there were significant and lasting improvements in mean echocardiographic gradients at 1 year. Event-free survival was 76% at one month and 69% at one year. CONCLUSIONS: Over the last decade, a rising trend of valve-in-valve procedures was observed. Despite an increase in procedures, complications show a contrasting decline with improved technical and device success over time. TiSAVR and TiTAVR showed comparable rates of procedural and device success as well as similar outcomes, highlighting the utility of valve-in-valve procedures in an aging population.

Dos and don'ts in large animal models of aortic insufficiency.

Aortic insufficiency caused by paravalvular leakage (PVL) is one of the most feared complications following transcatheter aortic valve replacement (TAVI) in patients. Domestic pigs (Sus scrofa domestica) are a popular large animal model to study such conditions and develop novel diagnostic and therapeutic techniques. However, the models based on prosthetic valve implantation are time intensive, costly, and often hamper further hemodynamic measurements such as PV loop and 4D MRI flow by causing implantation-related wall motion abnormalities and degradation of MR image quality. This study describes in detail, the establishment of a minimally invasive porcine model suitable to study the effects of mild-to-moderate "paravalvular" aortic regurgitation on left ventricular (LV) performance and blood flow patterns, particularly under the influence of altered afterload, preload, inotropic state, and heart rate. Six domestic pigs (Swiss large white, female, 60-70 kg of body weight) were used to establish this model. The defects on the hinge point of aortic leaflets and annulus were created percutaneously by the pierce-and-dilate technique either in the right coronary cusp (RCC) or in the non-coronary cusp (NCC). The hemodynamic changes as well as LV performance were recorded by PV loop measurements, while blood flow patterns were assessed by 4D MRI. LV performance was additionally challenged by pharmaceutically altering cardiac inotropy, chronotropy, and afterload. The presented work aims to elaborate the dos and don'ts in porcine models of aortic insufficiency and intends to steepen the learning curve for researchers planning to use this or similar models by giving valuable insights ranging from animal selection to vascular access choices, placement of PV Loop catheter, improvement of PV loop data acquisition and post-processing and finally the induction of paravalvular regurgitation of the aortic valve by a standardized and reproducible balloon induced defect in a precisely targeted region of the aortic valve.