Background: Mixed reality (MR) and its potential applications have gained increasing interest within the medical community over the recent years. The ability to integrate virtual objects into a real-world environment within a single video-see-through display is a topic that sparks imagination. Given these characteristics, MR could facilitate preoperative and preinterventional planning, provide intraoperative and intrainterventional guidance, and aid in education and training, thereby improving the skills and merits of surgeons and residents alike. Objective: In this narrative review, we provide a broad overview of the different applications of MR within the entire spectrum of surgical and interventional practice and elucidate on potential future directions. Methods: A targeted literature search within the PubMed, Embase, and Cochrane databases was performed regarding the application of MR within surgical and interventional practice. Studies were included if they met the criteria for technological readiness level 5, and as such, had to be validated in a relevant environment. Results: A total of 57 studies were included and divided into studies regarding preoperative and interventional planning, intraoperative and interventional guidance, as well as training and education. Conclusions: The overall experience with MR is positive. The main benefits of MR seem to be related to improved efficiency. Limitations primarily seem to be related to constraints associated with head-mounted display. Future directions should be aimed at improving head-mounted display technology as well as incorporation of MR within surgical microscopes, robots, and design of trials to prove superiority.

A common limitation to normothermic ex situ heart perfusion (ESHP) is functional decline. We previously designed a cardioprotective normothermic perfusion protocol, incorporating adenosine-lidocaine cardioplegia, subnormothermic reperfusion, pyruvate and methylprednisolone supplementation, and hemofiltration to prevent myocardial functional decline over 4 hours. In this study, we added continuous catecholamine infusion and protective loading conditions to assess the effectiveness of this enhanced cardioprotective perfusion protocol in preventing functional decline during extended normothermic perfusion in marginal porcine hearts. Six slaughterhouse pig hearts underwent 9 hours of normothermic ESHP using the enhanced cardioprotective protocol. Cardiac function was assessed at 90, 120, 240, 360, 480 and 540 minutes of ESHP. Subsequently, a preload-challenge was conducted after 9 hours to assess preload-responsiveness (mimicking the Frank-Starling principle) and suitability for transplantation. During perfusion, myocardial function remained stable, indicated by consistent mean cardiac index (9.2liter/min/kg at 90; 9.3liter/min/kg at 540 minutes of ESHP), left ventricular stroke work index (6,258mmHg*ml/kg at 90; 6,707mmHg*ml/kg at 540 minutes) and rate of ventricular pressure change over time. In response to a preload-challenge, there was a notable increase of 34% in mean cardiac index and 58% in mean stroke work. Our study demonstrates that the implementation of a cardioprotective protocol enables (very) marginal porcine slaughterhouse hearts, subjected to both a warm and cold ischemic insult prior to ESHP, to sustain satisfactory cardiac function without notable decline during 9 hours of normothermic ESHP, while also preserving their preload-responsiveness. The latter finding might indicate suitability for transplantation. This study provides a groundwork for further extending normothermic ESHP, unlocking the full potential of this promising technology.

Ex situ organ preservation by machine perfusion can improve preservation of organs for transplantation. Furthermore, machine perfusion opens up the possibilities for selective immunomodulation, creation of tolerance to ischemia-reperfusion injury and/or correction of a pathogenic genetic defect. The application of gene modifying therapies to treat heart diseases caused by pathogenic mutations during ex situ heart perfusion seems promising, especially given the limitations related to delivery of vectors that were encountered during clinical trials using in vivo cardiac gene therapy. By isolating the heart in a metabolically and immunologically favorable environment and preventing off-target effects and dilution, it is possible to directly control factors that enhance the success rate of cardiac gene therapy. A literature search of PubMed and Embase databases was performed to identify all relevant studies regarding gene therapy during ex situ heart perfusion, aiming to highlight important lessons learned and discuss future clinical prospects of this promising approach.

Background and Aims: Outcomes after surgical myectomy in hypertrophic obstructive cardiomyopathy (HOCM) patients have not been investigated in a multicentre registry with detailed clinical data. Hence, the objectives of this multicentre Dutch study are to describe the 30-day clinical outcomes after surgical myectomy, and to assess factors associated with increased 30-day complication rates. Methods: All HOCM patients (n = 335) who underwent surgery between 2012 and 2020 across 12 Dutch hospitals were analysed using data from the Netherlands Heart Registration. Multiple logistic regression analyses assessed factors associated with a higher 30-day complication rate. Results: Isolated surgical myectomy was performed in 22%, surgical myectomy with one concomitant procedure in 54%, and surgical myectomy with two or more concomitant procedures in 24%. Thirty-day complication rates concerned mortality (5%), ventricular septal defect (2%), stroke (3%), and surgical reoperation (2%). Mean resting left ventricular outflow tract (LVOT) gradient improved from 61 ± 30 mmHg to 13 ± 12 mmHg postoperatively, systolic anterior motion from 80% to 8%, and mitral regurgitation grade 3 or 4 from 31% to 6%. Low-volume hospital (<10 surgical myectomy procedures/year), female sex, and ≥2 concomitant procedures were significantly associated with increased 30-day complication rates. The adjusted 30-day complication rate was increased in low-volume hospitals (odds ratio 3.23 (95% confidence interval: 1.43–8.09); P = .007). Conclusions: Surgical myectomy with or without concomitant procedures effectively relieved LVOT obstruction in 93% of patients in this multicentre cohort. Female sex, ≥ 2 concomitant procedures, and low-volume hospitals were associated with higher 30-day complication rates. Although an inverse volume–complication relation was observed, this finding should be interpreted cautiously, and further investigation in larger sample size studies is warranted.

With an expanding population at risk for heart failure and the resulting increase in patients admitted to the waiting list for heart transplantation, the demand of viable organs exceeds the supply of suitable donor hearts. Use of hearts after circulatory death has reduced this deficit. Two primary techniques for heart procurement in circulatory death donors have been described: direct procurement and perfusion and thoraco-abdominal normothermic regional perfusion. While the former has been accepted as an option for heart procurement in circulatory death donors, the latter technique has raised some ethical questions in relation to the dead donor rule. In this paper we discuss the current dilemmas regarding these heart procurement protocols in circulatory death donors.

Despite an increasing population of patients supported with a left ventricular assist device (LVAD), it remains a complex therapy, and patients are frequently admitted. Therefore, a strict follow-u...