Sarcomere length in the beating heart: Synchronicity is optional

Helmes and Palmer review research by Kobirumaki-Shimozawa et al.

Robotic off-pump hybrid coronary revascularization - a niche area in need for objective data.

Hybrid coronary revascularization (HCR) consists of left internal thoracic artery (LITA) graft to the left anterior descending (LAD) artery and transcatheter revascularization of the non-LAD stenosis in specific settings to achieve complete coronary revascularization. Technique to perform the LITA to LAD graft has ranged from median sternotomy with cardiopulmonary bypass to robotically assisted totally endoscopic coronary bypass surgery using beating heart revascularization.

Thoracoscopic infrared ablation to create a box lesion as a treatment for atrial fibrillation

Background Creating a box lesion in the posterior wall of the left atrium from the epicardial side of the beating heart remains a challenge. Although a transmural lesion can be created by applying radiofrequency (RF) energy at clampable sites, it is still difficult to create a transmural lesion at unclampable sites because the inner blood flow in the unclampable free wall weakens the thermal effect on the outside. Our aim was to apply the newly developed infrared coagulator to create linear transmural lesions on the beating heart thoracoscopically to treat atrial fibrillation (AF). Case presentation A 71-year-old male was referred to our hospital with a diagnosis of hypertrophic cardiomyopathy and permanent atrial fibrillation. The patient was first diagnosed with atrial fibrillation 20 years before. Direct current cardioversion had been performed every few years a total of four times, but sinus rhythm restoration had always been temporary. On February 27, 2020, thoracoscopic PV isolation together with infrared roof- and bottom-line ablation to create a box lesion and left atrial appendage amputation (LAAA) were performed. The coagulator could be applied to clinical thoracoscopic surgery to successfully create a box lesion without any complication. The patient restored a regular sinus rhythm, it has been maintained for eleven months, and there have been no adverse events. Conclusions The infrared coagulator might have enough potential to create transmural lesions on the beating heart in thoracoscopic AF surgery.

Pope Francis’ Renewal of Pastoral Care in the Logic of Mercy

By showing people mercy, God points to the Church the way to fulfill her saving mission in the world. According to Pope Francis, the renewal of pastoral activity should be carried out in the logic of God’s mercy. As the beating heart of the Gospel, it should be at the center of the message of salvation communicated to people and give shape to pastoral care. The operationalization of the truth about God’s mercy leads pastors to adopt the attitude of going to the periphery of existence, to bring forgiveness and comfort to people wounded by sin, and to be ready to accompany them in achieving full Christian maturity. Their motivation to perform the service in imitation of Jesus Christ, who is the perfect personification of God’s mercy, cannot be weakened by misunderstandings, the disappearance of sin consciousness or a relativistic approach to moral values and principles. Acting in accordance with the logic of mercy, the Church bears witness to her fidelity to God and makes a significant contribution to building a more human world.

Computer Modeling of Radiofrequency Cardiac Ablation including Heartbeat-Induced Electrode Displacement

Background: The state of the art in computer modeling of radiofrequency catheter ablation (RFCA) only considers a static model, i.e. it does not allow modeling ablation electrode displacements induced by tissue movement due to heartbeats. This feature is theoretically required, since heartbeat-induced changes in contact force can be detected during this clinical procedure. Methods: We built a 2D RFCA model coupling electrical, thermal and mechanical problems and simulated a standard energy setting (25 W - 30 s). The mechanical interaction between the ablation electrode and tissue was dynamically modeled to reproduce heartbeat-induced changes in the electrode insertion depth from 0.86 to 2.05 mm, which corresponded with contact forces between 10 and 30 g when cardiac tissue was modeled by a hyperelastic Neo-Hookean model with a Young's modulus of 75 kPa and Poisson's ratio of 0.49. Results: The dynamic model computed a lesion depth of 5.86 mm, which is within the range of previous experimental results based on a beating heart for a similar energy setting and contact force (5.6-6.7 mm). Lesion size was practically identical (differences less than 0.02 mm) to that using a static model with the electrode inserted to an average depth (1.46 mm, equivalent to 20 g contact force). Conclusions: The RFCA dynamic model including heartbeat-induced electrode displacement predicts lesion depth reasonably well compared to previous experimental results based on a beating heart model, however this is true only at a standard energy setting and moderate contact force.

Cardiac Organoids and Gastruloids to Study Physio-Pathological Heart Development

Ethical issues restrict research on human embryos, therefore calling for in vitro models to study human embryonic development including the formation of the first functional organ, the heart. For the last five years, two major models have been under development, namely the human gastruloids and the cardiac organoids. While the first one mainly recapitulates the gastrulation and is still limited to investigate cardiac development, the second one is becoming more and more helpful to mimic a functional beating heart. The review reports and discusses seminal works in the fields of human gastruloids and cardiac organoids. It further describes technologies which improve the formation of cardiac organoids. Finally, we propose some lines of research towards the building of beating mini-hearts in vitro for more relevant functional studies.