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Coronary blood flow is tightly regulated to ensure that myocardial oxygen delivery meets local metabolic demand via the concurrent action of myogenic, neural and metabolic mechanisms. Although several competing hypotheses exist, the specific nature of the local metabolic mechanism(s) remains poorly defined. To gain insights into the viability of putative metabolic feedback mechanisms and into the co-ordinated action of parallel regulatory mechanisms, we applied a multiscale modelling framework to analyse experimental data on coronary pressure, flow and myocardial oxygen delivery in the porcine heart in vivo. The modelling framework integrates a previously established lumped-parameter model of myocardial perfusion used to account for transmural haemodynamic variations and a simple vessel mechanics model used to simulate the vascular tone in each of three myocardial layers. Vascular tone in the resistance vessel mechanics model is governed by input stimuli from the myogenic, metabolic and autonomic control mechanisms. Seven competing formulations of the metabolic feedback mechanism are implemented in the modelling framework, and associated model simulations are compared with experimental data on coronary pressures and flows under a range of experimental conditions designed to interrogate the governing control mechanisms. Analysis identifies a maximally probable metabolic mechanism among the seven tested models, in which production of a metabolic signalling factor is proportional to myocardial oxygen consumption and delivery is proportional to flow. Finally, the identified model is validated based on comparisons of simulations with data on the myocardial perfusion response to conscious exercise that were not used for model identification. KEY POINTS: Although several competing hypotheses exist, we lack knowledge of specific nature of the metabolic mechanism(s) governing regional myocardial perfusion. Moreover, we lack an understanding of how parallel myogenic, adrenergic/autonomic and metabolic mechanisms work together to regulatory oxygen delivery in the beating heart. We have developed a multiscale modelling framework to test competing hypotheses against experimental data on coronary pressure, flow and myocardial oxygen delivery in the porcine heart in vivo. The analysis identifies a maximally probable metabolic mechanism among seven tested models, in which the production of a metabolic signalling factor is proportional to myocardial oxygen consumption and delivery is proportional to flow.

Background A high-fidelity simulator that uses a perfused porcine heart, cannulae, and tubing has been demonstrated to be a useful training adjunct. We hypothesized that multimodal assessment of cardiopulmonary bypass (CPB) skills within this high-fidelity simulated environment could discern expert from trainee performance. Methods Three traditional fellows (postgraduate year 6-8) and 3 attending surgeons each performed 3 aortic cannulations. The third sequence included venous cannulation, commencement of CPB, and placement of a cardioplegia catheter and aortic cross-clamp. Performance across 20 cognitive and 21 technical domains was evaluated. Surgeon and assistant hand movements and economy of motion were assessed by electromagnetic motion sensors worn under sterile gloves. Results Analysis showed a significant difference in cognitive (6.7 ± 2.3 vs 4.6 ± 2.7, P = .03) but not technical (6.2 ± 2.5 vs 5.8 ± 2.2, P = .7) scores favoring the experts. In addition, experts showed higher efficiency by spending 64 ± 14 seconds to construct a nonpledgeted aortic purse-string suture and secure it with a Rummel, while trainees spent 82 ± 30 seconds to complete this task (P = .03). Motion analysis revealed similar path lengths between experts and trainees for cannulation and CPB but significantly shorter path lengths for experts in cross-clamp (47.5 ± 15.5 m vs 91.9 ± 20.3 m, P = .04). Conclusions Multimodal assessment using cognitive, technical, and motion analysis of basic CPB tasks using a high-fidelity simulation environment is a valid system to measure performance and discriminate experts from trainees. This construct may allow for development of “competence thresholds” with important implications for training and certification in cardiothoracic surgery.

LifeTec Group has developed a Cardiac Biosimulator where a dead porcine heart is used to mimic a beating heart in a simulated environment. This is useful for assessment of medical devices or as a training platform for medical professionals. The research presented aims at extending this simulator by designing feedback controllers for the time-averaged relevant pressures and flow, which reduces the startup time and potentially increases stability of the simulator. To achieve this, both the continuous and time-averaged models of the simulator are presented together with their state-space representations. The proposed controller consists of three independent PI controllers, which are presented along with simulation and measurement results and show promising system performance. Lastly, the controller implementation was tested on the Biosimulator with a pathological heart (Mitral prolapse), which showed no significant decrease in performance compared to the physiological heart.

An epicardial bioelectronic patch is an important device for investigating and treating heart diseases. The ideal device should possess cardiac-tissue-like mechanical softness and deformability, and be able to perform spatiotemporal mapping of cardiac conduction characteristics and other physical parameters. However, existing patches constructed from rigid materials with structurally engineered mechanical stretchability still have a hard–soft interface with the epicardium, which can strain cardiac tissue and does not allow for deformation with a beating heart. Alternatively, patches made from intrinsically soft materials lack spatiotemporal mapping or sensing capabilities. Here, we report an epicardial bioelectronic patch that is made from materials matching the mechanical softness of heart tissue and can perform spatiotemporal mapping of electrophysiological activity, as well as strain and temperature sensing. Its capabilities are illustrated on a beating porcine heart. We also show that the patch can provide therapeutic capabilities (electrical pacing and thermal ablation), and that a rubbery mechanoelectrical transducer can harvest energy from heart beats, potentially providing a power source for epicardial devices. An epicardial patch made from materials that match the mechanical softness of heart tissue can perform spatiotemporal mapping of electrophysiological activity, as well as strain and temperature sensing, pacing and ablation therapies, and energy harvesting, while deforming with a beating heart.

The aim of this study was to perform a pilot histological and quantitative analysis of the blood vessels accompanying the epicardial nerves (vasa nervorum) in the porcine hearts. Twenty healthy porcine hearts were used in this study. The blood vessels were analyzed by light microscopy using four different staining techniques in transverse sections taken from the upper, middle, and lower segments of the anterior part of the interventricular region and the adjacent parts of the right and left ventricles containing epicardial nerves and the endocardial peripheral parts of the Purkinje fibers. In total, 317 epicardial nerves were detected. The vasa nervorum were present in 75.7% of these nerves. The vasa nervorum resembled arterioles and postcapillary and collecting venules. One hundred and forty nine epicardial nerves were perivascular, located in the adventitia of the anterior interventricular artery and vein. The remaining 168 nerves ran freely through the epicardial interstitium. The presence of the vasa nervorum was not related to topographical location or nerve diameter. Additionally, from a total of 33 analyzed ventricular complexes of Purkinje fibers small blood vessels located in their proximity were identified in only two cases. It can be concluded that the majority of the anterior epicardial nerves of porcine heart possess well-developed vasa nervorum. In contrast, similar blood vessels are rarely present in the vicinity of the Purkinje fibers. The data obtained contribute to a better understanding of the nutrition of the cardiac nerves.

This study aimed to verify the reliability of ablation index (AI) for ablation lesion estimating with different settings for radiofrequency (RF) parameters: power, impedance, contact angles, irrigation rate, temperature of irrigation saline, and irrigation solution. RF ablations (N = 66) were performed on ex vivo porcine left ventricle submerged in 37 °C saline. The aforementioned ablation parameters were changed to measure whether the size of the ablation lesion was consistent at a fixed AI value of 500. The maximum lesion diameter (r = - 0.631, P = 0.028), depth (r = - 0.896, P 0.001), and volume (r = - 0.745, P 0.005) were significantly reduced with an increase of the impedance. The lesion depth (P 0.05) and the lesion volume (P 0.05) were significantly larger with glucose irrigation than saline irrigation. In conclusion, at a fixed AI value, impedance and irrigation solution have impact on the ablation lesions, which could affect the accuracy of AI formula to estimate ablation lesion size. Graphical abstract.

Inherent and acquired factors determine the integrated autonomic response to cardiovascular stressors. Excessive sympathoexcitation to ischemic stress is a major contributor to the potential for sudden cardiac death. To define fundamental aspects of cardiac-related autonomic neural network interactions within the thoracic cord, specifically as related to modulating sympathetic preganglionic (SPN) neural activity. Adult, anesthetized Yorkshire pigs ( n = 10) were implanted with penetrating high-density microarrays (64 electrodes) at the T2 level of the thoracic spinal cord to record extracellular potentials concurrently from left-sided dorsal horn (DH) and SPN neurons. Electrical stimulation of the T2 paravertebral chain allowed for antidromic identification of SPNs located in the intermediolateral cell column (57 of total 1,760 recorded neurons). Cardiac stressors included epicardial touch, occlusion of great vessels to transiently alter preload/afterload, and transient occlusion of the left anterior descending coronary artery (LAD). Spatial/temporal assessment of network interactions was characterized by cross-correlation analysis. While some DH neurons responded solely to changes in preload/afterload (8.5 ± 1.9%) or ischemic stress (10.5 ± 3.9%), the majority of cardiovascular-related DH neurons were multimodal (30.2 ± 4.7%) with ischemia sensitivity being one of the modalities (26.1 ± 4.7%). The sympathoexcitation associated with transient LAD occlusion was associated with increased correlations from baseline within DH neurons (2.43 ± 0.61 to 7.30 ± 1.84%, P = 0.04) and between SPN to DH neurons (1.32 ± 0.78 to 7.24 ± 1.84%, P = 0.02). DH to SPN network correlations were reduced during great vessel occlusion. In conclusion, increased intrasegmental network coherence within the thoracic spinal cord contributes to myocardial ischemia-induced sympathoexcitation. NEW & NOTEWORTHY In an in vivo pig model, we demonstrate using novel high-resolution neural electrode arrays that increased intrasegmental network coherence within the thoracic spinal cord contributes to myocardial ischemia-induced sympathoexcitation.

We identified an extremely rare congenital porcine type 0 lateral bicuspid aortic valve from a fresh porcine heart. Using a 3-dimensionally printed ex vivo left heart simulator, we analyzed valvular hemodynamics at baseline, in an aortic aneurysm disease model, and after valve-sparing root replacement. We showed that bicuspid aortic valve regurgitation due to aortic aneurysm can be successfully repaired without significant hemodynamic impairment using the valve-sparing root replacement technique in an individualized approach. Our results provide direct hemodynamic evidence supporting the use of valve-sparing root replacement for patients with bicuspid aortic valve regurgitation.

BACKGROUND The radiofrequency impedance measurement is one of the basic parameters monitored during ablation procedures. An abrupt rise in impedance is often observed corresponding to a steam pop. The exact correlation between the occurrence of steam pop and subsequent rise in impedance has not been experimentally described so far. OBJECTIVES To evaluate the relationship between steam pop occurrence and impedance fluctuations observed during radiofrequency ablation (RFA). MATERIAL AND METHODS Porcine heart tissue specimens were appropriately prepared and placed in an experimental setup connected to electrophysiological equipment with 3D anatomical mapping facilities. The RFA lesions were performed in standardized conditions with the use of contact force measurement-enabled open irrigation ablation catheter (ThermoCool SmartTouch™, 3.5 mm tip, F-J curvature; Biosense Webster, Irvine, USA) in the power-control mode. The RFA delivery was stopped when the steam pop occurred. Time taken for the steam pop to occur and to the subsequent abrupt impedance rise was recorded, along with the impedance fluctuations during an application. RESULTS In total, 25 experimental radiofrequency (RF) current deliveries ended up with steam pops, which occurred after 30-60 s. The time recorded from the beginning of the application up to the steam pop was shorter if increased power was applied (35 W compared to 30 W: 41.5 ±9.9 s compared to 49.9 ±8.2 s; p = 0.046). During all RF applications, impedance significantly but gradually decreased from 122.9 ±7.9 Ω to 87.5 ±3.6 Ω (p < 0.001) with a mean drop rate of 0.8 ±0.2 Ω/s. During all experiments, the abrupt and significant impedance increase (8.2 ±2.0 Ω, p < 0.001) was observed always after steam pop occurrence (207.4 ±155.9 ms). CONCLUSIONS During RF current delivery which ended up with steam pop, an abrupt impedance increase was always registered after the occurrence of this phenomenon. Therefore, the impedance rise observed during steam popping cannot be used for its prediction. The time to steam pop was shorter for applications with increased power but not with greater contact force.

Aims Contact force (CF) between radiofrequency (RF) ablation catheter and myocardium and ablation index (AI) correlates with RF lesion depth and width in normal-voltage (>1.5 mV) myocardium (NVM). We investigate the impact of CF on RF lesion depth and width in low ( Methods and results Twelve weeks after myocardial infarction, 10 pigs underwent electroanatomical mapping and endocardial RF ablations were deployed in NVM, IVM, and LVM myocardium. In vivo ncMRI was performed before the heart was excised and subjected to gross anatomical evaluation. Ninety (82%) RF lesions were evaluated. Radiofrequency lesion depth and width were smaller in IVM and LVM compared with NVM (P Conclusions Radiofrequency lesions deployed by similar duration, power and CF are smaller in IVM and LVM than in NVM. Radiofrequency lesion depth and width correlated with CF, AI, and impedance drop in NVM and IVM but not in LVM. Native contrast magnetic resonance imaging may be useful to assess RF lesion depth and width in NVM, IVM, and LVM.

Implantable medical devices are widely used for monitoring and treatment of severe diseases. In particular, an implantable cardiac pacemaker is the most effective therapeutic device for treating bradyrhythmia, however its surgical replacement is inevitable every 5-12 years due to the limited life of the built-in battery. Although several approaches of energy harvesting have been explored in this decade for powering cardiac pacemakers, the modern, commercial, and full-function pacemaker has never been powered effectively yet. Here, we report an integrated strategy for directly powering a modern and full-function cardiac pacemaker, which can pace the porcine heart in vivo by harvesting the natural energy of a heartbeat, without using any external energy storage element. The generator includes an elastic skeleton and two piezoelectric composites, which could generate a high-output current of 15 μA in vivo over state-of-the-art performance. This study makes an impressive step toward fabricating a self-powered cardiac pacemaker and resolving the power issue of implantable medical devices by piezoelectric harvesting technology.

Atrial fibrillation is a heart condition commonly treated by cardiac ablation procedures. Since the esophagus is positioned in close proximity to the heart, esophageal thermal damage can occur during ablation. In this study, we investigate the temperature rise on the inner esophagus surface using a 2D temperature sensor array. An experimental study was performed to measure temperature by the sensor array placed on inner porcine esophagus tissue as a constant temperature heat source is applied to the inner porcine atrial tissue. A numerical model was developed to complement the experimental study.

Purpose Our previous study confirmed that not only force but also the catheter contact angle substantially impacted the contact area and its morphology. Therefore, in this study, we aimed to further investigate the relationship between the catheter contact area and the dimensions of the ablation lesion area as a function of catheter contact angle and force in radiofrequency catheter ablation. Methods The radiofrequency catheter ablation test was performed for 5 contact angles and 8 contact forces at a fixed ablation time of 30 s. The initial impedance was 92.5 ± 2.5 Ω, the temperature during ablation was 30 °C, and the power was 30 W. The irrigation rate during ablation was set to 17 mL/min. Each experiment was repeated 6 times. Results The catheter contact area showed a strong correlation with the ablation lesion area (r = 0.8507). When the contact area was increased, the lesion area also increased linearly in a monotonic manner. The relationships between catheter contact force and ablation lesion area and between catheter contact force and ablation lesion depth are logarithmic functions in which increased contact force was associated with increased lesion area and depth. The catheter contact angle is also an important determinant of the lesion area. The lesion area progressively increased when the contact angle was decreased. In contrast, the lesion depth progressively increased when the contact angle was increased. Conclusions The catheter contact area was strongly correlated with the ablation lesion area. Additionally, catheter contact force and contact angle significantly impacted the dimensions of the lesion in radiofrequency catheter ablation procedures.

The apprenticeship model of surgical education, relying solely on operating room training, may be insufficient to meet current needs of cardiac surgery trainees. Challenges such as resident duty hour restrictions, increasing case complexity, and novel techniques limit direct intraoperative experience. Simulation is a widely accepted educational tool in surgery. The purpose of this study was to establish an understanding of the current use of simulation in Canadian cardiac surgery and to examine the attitudes of Canadian educators and residents toward simulation training. Canadian cardiac surgery residents and faculty surgeons were surveyed at each of the 12 Canadian academic institutions. Simulation was used in all 12 academic programs, with the average use being 3 to 4 times a year. The most common simulators used were anastomotic task trainers and porcine heart models. Simulation sessions were deemed incomplete, lacking clearly stated learning objectives and evaluations. There was an overall desire from both residents and faculty surgeons to have more simulation use at their centres. This study identified that although simulation is used and valued within Canada, it is not yet employed to maximum potential. Simulation cannot replace operative experience, but current demands on surgeons and residents mandates a broader, more effective application of simulation as an educational adjunct.

We are developing a new IR imaging technique, enhanced thermal imaging, that can delineate blood vessels embedded in water-rich tissue in real time. The technique is a combination of thermal IR imaging (8-10 μm) and selective heating of blood (∼0.5°C) relative to surrounding water-rich tissue using LED sources (530 nm) at low powers (irradiance

Background The study was performed to compare the efficacy and safety during radiofrequency ablation (RFA) using ThermoCool SmartTouch (ST) and ThermoCool SmartTouch-SF (STSF) catheters in the porcine heart. Methods and results RFA was performed on the porcine myocardium by using two irrigated ablation catheters. Three groups were divided based on the different contact forces (CFs): low contact force (LCF) (1-3 g), medium contact force (MCF) (5-10 g), and high contact force (HCF) (15-20 g). In each group, RFA was delivered at four power settings of 30, 40, 50, 60 W. At each power, RFA was applied to reach the target ablation index (AI) of 350, 450, and 500. Altogether, 360 RF lesions were created by using 72 ablation conditions. AI value was positively correlated with lesion size using ST and STSF catheters. At a fixed power, lesion dimensions significantly smaller in the LCF group, whereas did not differ between MCF and HCF groups. Furthermore, at a fixed CF, lesion dimensions increased with power set at 40 W compared with 30 W but decreased with high-power RF energy (50 and 60 W). Although the average lesion surface diameter and the maximum diameter was increased using the STSF catheter, there were no significant differences in LV between the two catheters. The steam pop provoked more frequently using ST catheter and showed a negative correlation with CF and positive correlation with high-power energy. Conclusion The STSF catheter is safer and equally effective in lesion formation compared with the ST catheter. LV was increased along with the early increase of CF and power, whereas a further increase of CF and power significantly reduces the lesion size.

Advancements in computational techniques will soon enable the use of anatomically realistic virtual models to contribute towards regulatory evidence. In this study we introduce methods to construct and validate a subject-specific four-chamber porcine heart model suitable to investigate coupled electro-mechanical phenomena from in vivo data. Our geometrically detailed, electromechanical four-chamber heart was mechanically calibrated to match the experimentally recorded LV pressure-volume loop. Surfaces of the LV and RV from the model were validated against surfaces extracted from in vivo CT scans, which correlated well (R2 =0.94, 0.95 respectively) over all phases. Validated model function is compared with simulations of AV block in the same subject. Our findings show that in addition to interrupted flow, AV block creates elevated stress and strain throughout the heart during diastole following the missed ventricular beat. The ventricles, unable to unload, are subjected to increased pressures and volumes which peak during the atrial kick. At this point mean ventricular stress were elevated by 50% (3.0 vs. 4.5 kPa, normal vs. AV block). Our study validates an electromechanical four-chamber heart model and demonstrates model utility to investigate pathology using a “digital twin”.

Meat byproducts, such as the internal organs from slaughtered animals, are usually underutilized materials with low commercial value. The functional (emulsifying, gelling, and foaming) properties of soluble protein extracts derived from pork hearts were investigated, as well as their molecular weight distribution. A central composite design (CCD) for two process variables (pH and ionic strength of the extraction buffer) was used to foreknow the effects of the process conditions on the physicochemical characteristics and technofunctionality of the protein extracts by means of the response surface methodology (RSM). SDS-PAGE patterns of the heart protein solutions revealed multiple bands with molecular weights ranging from 15 to 220 kDa, mainly corresponding to sarcoplasmic, myofibrillar, as well as blood proteins. The best extraction conditions to obtain protein fractions with good foaming properties would correspond to acid pH (pH &le, 5) and high salt content (2&ndash, 4%). On the contrary, solutions recovered at pH &gt, 5 with low NaCl contents were the ones showing better emulsifying properties. Regarding gelation ability, heat-induced gels were obtained from extracts at pH 6.5&ndash, 8, which showed improved firmness with increasing NaCl content (2&ndash, 4%). Satisfactory second-order polynomial models were obtained for all the studied response variables, which can be useful in guiding the development of functional ingredients tailored for specific uses to maximize applications.

Collagen fibers are a primary load-bearing component of connective tissues and are therefore central to tissue biomechanics and pathophysiology. Understanding collagen architecture and behavior under dynamic loading requires a quantitative imaging technique with simultaneously high spatial and temporal resolutions. Suitable techniques are thus rare and often inaccessible. In this study, we present instant polarized light microscopy (IPOL), in which a single snapshot image encodes information on fiber orientation and retardance, thus fulfilling the requirement. We utilized both simulation and experimental data from collagenous tissues of chicken tendon, sheep eye, and porcine heart to evaluate the effectiveness of IPOL as a quantitative imaging technique. We demonstrate that IPOL allows quantitative characterization of micron-scale collagen fiber architecture at full camera frame rates (156 frames/second herein).

Malfunctioning heart valves can cause severe health problems, which if left untreated can lead to death. One of the treatment options is to replace a diseased heart valve with a decellularized valve construct prepared from human or animal material. Decellularized tissue scaffolds closely resemble properties of native tissue, while lacking immunogenic factors of cellular components. After transplantation, circulating stem and progenitor cells of the patient adhere to the scaffold resulting in in vivo tissue regeneration of the valve. Decellularized heart valve scaffold implants need to be stored to be readily available whenever needed, which can be done by freeze-drying. The advantage of freeze-drying is that it does not require bulky and energy-consuming freezing equipment for storage and allows easy transport. This chapter outlines the entire process from decellularization to freeze-drying to obtain dry decellularized heart valves, which after a simple rehydration step, can be used as implants. The protocol is described for porcine heart valves, but procedures can easily be adapted for material obtained from other species.

INTRODUCTION Few studies have examined heat transfer and thermal injury on the epiesophageal surface during radiofrequency application, or compared the risk of esophageal thermal injury between standard and high-power, short-duration (HPSD) ablation. We studied the thermodynamics of HPSD and standard ablation at different tissue interfaces between the left atrium and esophagus, focusing on epiesophageal temperature changes and thermal injury. METHODS AND RESULTS Fresh porcine heart and esophageal sections were secured to a custom holder and submerged in a temperature-controlled, circulating water bath. During ablation, thermistors recorded temperatures at the catheter tip-atrial interface, epiesophageal-atrial interface, and esophageal lumen. Samples were ablated in triplicate with the following parameters: contact force (15/25g), power (10/20/30 W standard; 40/45/50 W HPSD), and duration (10/20/30 s standard; 5/10/15 s HPSD). Epiesophageal and endoluminal temperature rises were greater in HPSD than in standard ablation (epiesophageal: 5.9 ± 5.6 vs. 2.2 ± 2.0°C, p

Contact force (CF) catheters are useful to address proper contact during ablation. However, interactions between the ablation process, or its associated irrigation flow changes, with the CF sensing may translate into unexpected CF value fluctuations. We aimed to test for unintentional CF value variations during radiofrequency applications at a fixed applied force, with two commercially available catheters (TactiCath™ and SmartTouch™), and to evaluate its theoretical clinical significance by correlating CF-derived automatic ablation algorithms (force-time integral and lesion index) and actual lesion size at two standard CF values. Four series of 20 perpendicular epicardial ablations (20 W, 60 s, 17 ml/min) were performed on porcine left ventricle submerged in 37 °C saline. Catheters were mechanically fixed at a constant position and evaluated at 10 and 20 g. CF values were digitally analysed before each application changing irrigation rate (2–17–30 ml/min), and during ablation. Finally, lesions were quantified. Increasing irrigation before ablation led to a slight but significant CF decrease. During ablation, CF showed a reproducible pattern: fast initial decrease, subsequent increase until higher-than-initial values and final plateau phase (CF variation up to 69% at 10 g). CF variability was significantly higher at 10 g and using TactiCath™. There were no major differences in lesion size between catheters at the same initial CF. CF only correlated mildly to lesion measures, and automatic algorithms globally failed to predict lesion size. CF measured values spontaneously vary during ablation following a predictable pattern (initial decrease, subsequent increase and final plateau). This is especially remarkable applying lower CF.

Background The left-sided atrial septal pouch (SP), a recently re-discovered anatomical structure within the human interatrial septum, has emerged as a possible source of thrombi formation and a trigger for atrial fibrillation, thereby potentially increasing the risk for ischemic stroke. In many studies, the swine interatrial septum has been used as model of the human heart. Also, possible new strategies and devices for management of the SPs may first be tested in this pig model. Therefore, in this study, we aimed to evaluate swine interatrial septum morphology and to compare it with the human analog, especially in the light of SP occurrence. Methods A total of 75 swine (Sus scrofa f. domestica) hearts were examined. The interatrial septum morphology was assessed, and SPs were measured. Results The most common variant of the interatrial septum was smooth septum (26.6%) followed by the patent foramen ovale channel and right SP (both 22.7%). No left or double SPs were observed. In 28.0% of all cases the fold of tissue (left septal ridge) was observed on the left side of the interatrial septum in the location where the left-sided SP should be expected. The mean length of the patent foramen ovale channel was 7.1 ± 1.5 mm. The mean right SP depth was 6.3 ± 2.2 mm, and its ostium width and height were 5.8 ± 1.2 and 5.3 ± 1.6 mm, respectively. Conclusions There are significant differences between human and porcine interatrial septum morphology that should be taken into account during experimental studies. The absence of the left SP in swine results in the inability to use porcine heart as an experimental model for left-sided SP management.

Objectives. Electrical impedance spectroscopy (EIS) is a harmless non-invasive technique that allows to measure and monitor different physiological parameters. One of the problems with establishing new procedures based on EIS is difficulty to distinguish between tissue types. For that reason, our research group have decided to assess a possibility to use nanomagnetite as a contrast medium in EIS procedures. In this work we present characterization the electrical properties of a porcine heart tissue by EIS using a magnetite particles suspension as contrast medium. Methodology. SP-150 from BioLogic Science Instruments was used as EIS equipment. Porcine heart tissue was used as biological tissue. Nanomagnetite particles were synthetized by coprecipitation and combustion methods and named NM1 and NM2, respectively. EIS device was connected at each ventricle through four hypodermic needles (38mm). Left and right ventricle was injected with NM1 and NM2 particles, respectively. Impedance measurements were acquired for each ventricle before and after the injection. Contribution. Both samples of magnetite nanoparticles were able to change electrical properties of heart tissue. Studies in vivo must be performed in order to confirm the conclusion.

Textile manufacturing of silk generates unwindable raw silk fibers, which are treated as silk wastes for downcycling applications, thus unexpectedly demoting the luxury status of silk. As a primary trial seeking to reshape the destiny of silk wastes, the present study is focused on transforming natural silk nonwovens, as a typical model of artificial silk nonwovens, into bioadhesives for tissue repair. Herein, a technique is demonstrated for the preparation of a transparent and stretchable adhesive from a silkworm cocoon sheet (SCS), a typical natural silk nonwoven. This technique differs from the traditional method of completely dissolving silk fibers to obtain silk fibroin. Specifically, the technique entailed pretreatment of the SCS with a CaCl2-ethanol-H2O ternary solution to obtain a modified cocoon sheet (MCS), followed by surface modification with a CaCl2-formic acid (Ca-FA) solution to obtain MCS@Ca with controllable adhesion, which was achieved by adjusting the Ca2+ content in Ca-FA. The highly stretchable MCS@Ca firmly adhered to various substrates for loads as high as 54 kPa, and its performance in repairing an injured liver in vivo was superior to that of a commercial product, Sorbalgon®. Additionally, MCS@Ca effectively sealed a freshly punctured porcine heart and stomach ex vivo, thereby demonstrating its potential as a sealant. To our knowledge, this is the first trial study for on upcycling disqualified silk fibers using a convenient top-down approach to prepare robust bioadhesives for tissue repair, wherein MCS@Ca may serve to bridge the gap between advanced biomaterials and disqualified silk wastes.

The use of protein hydrolyzates in food and feed ingredients is a growing area of interest. The present study was conducted aiming to determine the standardized ileal digestibility (SID) and to evaluate protein quality of porcine and bovine hydrolyzates. The SID values were determined in pigs and these values were used to calculate digestible indispensable amino acid score (DIAAS) values.; Results: The SID of crude protein of hydrolyzates of porcine plasma, bovine muscle, bovine collagen, porcine heart and porcine muscle was 0.81, 0.84, 0.79, 0.79 and 0.91, respectively. Based on the DIAAS, hydrolyzates of porcine plasma and porcine heart (DIAAS = 87 and 76) are considered as good quality protein sources for younger children. For older children, adolescents and adults, the hydrolyzates of bovine muscle and porcine heart (DIAAS = 81 and 87) are considered as good quality protein sources and the hydrolyzate of porcine plasma (DIAAS = 102) is considered as a high quality protein source.; Conclusion: DIAAS values indicate that the porcine and bovine hydrolyzates tested in the present study have low and medium to high protein values and also that the protein products can be included in human nutrition. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

Summary Recently, a new interstitial cell type called telocyte has been identified. Telocytes are found in many organs including the heart, where they are especially well described. However, their presence in the porcine heart has not yet been proven. The pig is a valuable animal model in research because of its resemblance with man, making it interesting to determine whether telocytes can be found in pigs as well. The focus of this study is the identification and ultrastructural description of telocytes in the heart tissue of pig. Using transmission electron microscopy, telocytes were found in both left and right atrium and ventricle, usually close to cardiomyocytes and/or blood vessels. Their most important characteristic is the long cytoplasmic processes called telopodes, which have a moniliform aspect, measure tens of μm and usually have a thickness below 0.2 μm. This unique morphological feature enables telocytes to be recognized from other interstitial cells such as fibroblasts. Additional observations include the ability to release extracellular vesicles and to make contacts with other structures such as endothelial cells, suggesting a role in intercellular communication.

Proper blood flow through the atrioventricular heart valves relies on the holistic function of the valve and subvalvular structures, and failure of any component can lead to life-threatening heart disease. A comprehension of the mechanical characteristics of the healthy valve components is necessary for the refinement of heart valve computational models. In previous studies, the chordae tendineae have been mechanically characterized as individual structures, usually in a clamping-based approach, which may not accurately reflect the in vivo chordal interactions with the leaflet and papillary muscles insertion regions. In this study, we performed uniaxial mechanical testing of strut chordae tendineae of the atrioventricular heart valves under a unique tine-based leaflet-chordae-papillary muscle testing to observe the chordae mechanics with preserved subvalvular component interactions. Results of this study provided insight to the disparity of chordae tissue stress-stretch responses between the mitral valve (MV) and the tricuspid valve (TV) under their respective emulated physiological loading. Specifically, strut chordae tendineae of the MV anterior leaflet had peak stretches of 1.09–1.16, while peak stretches of 1.08–1.11 were found for the TV anterior leaflet strut chordae. Constitutive parameters were also derived for the chordae tissue specimens using an Ogden model, which is useful for computational model refinement. Results of this study are beneficial to the eventual improvement of treatment methods for valvular disease.

Laserballoon-based pulmonary vein isolation has proven to be safe and effective. However, the influence of the laser energy titration on the lesion formation has never been fully investigated. The aim of this study was to determine the relationship between the delivered laser energy and lesion size, as well as the incidence of steam pop.The whole porcine heart was excised, and the left ventricular myocardium was separated into four specimens. Myocardial specimens were embedded in a warm mattress to keep the myocardial temperature around 37°C. The laserballoon was located so that the surface of the laserballoon was attached to the myocardium. The laser energy was irradiated against the surface of myocardium at 5.5, 8.5, 10.0, and 12.0 W for 3, 5, 10, and 20 seconds. The depth, surface area, and lesion volume were measured using a digital vernier caliper.At constant laser energy and time, the lesion size increased significantly with the increasing energy (P < 0.001) and application duration (P < 0.001). The steam pop was provoked when a 12.0 W laser energy was applied for longer than 16 seconds, and it occurred in 2 out of 8 lesions.The laserballoon demonstrated the ability to create a lesion formation in a dose- and time-dependent manner. Steam pop could be provoked with high-energy irradiation.

The use of hydrogels derived from the extracellular matrix (ECM) in tissue engineering applications aims to overcome the conundrum of mimicking the complexity of ECM composition in vitro. In this chapter, we describe a method of decellularization and subsequent formation of an ECM-based hydrogel using porcine heart tissue. These decellularized ECM hydrogels could be used to create semi-interpenetrating networks or as bioinks in bioprinting applications to further enhance the bioactivity and increase the biomimicry degree of the biological cardiac constructs.

The allogenic or xenogenic organs such as the heart, liver, lung or kidney could be a convenient sours of biocompatible scaffolds for autologous cell seeding in order to obtaining the new organs, immunologically compatible to suffering patients. Comparing to the biomimetic scaffolds, obtaining through macromolecular chemistry procedures, decellularization of tissues or organs provide an increased fidelity of architecture and chemical composition of the cell microenvironment, as well a highly similarity of anatomical structure, including the existence of the network of blood vessels, which is still a big challenge for tissue engineering. This paper is a preliminary work that set a perfusion protocol for porcine heart decelularization. As result of combined action of enzimatic, detergent and clearance agents, a decellularized heart with a slightly modified porosity of the extracellular matrix has been achieved.