Myocardial calcification: case reports and a systematic review.

Aims: Myocardial calcification is an unusual condition in which excess calcium is deposited in the myocardium. Herein, we report two cases of myocardial calcification from our clinical experience. Furthermore, we conduct a systematic review to examine the clinical course and associated pathologies of myocardial calcification. Methods and results: This systematic review was registered in PROSPERO (CRD42023463285). PubMed and Scopus were searched according to the following inclusion criteria: (i) case reports or case series describing patients with myocardial calcification; (ii) diagnosis of myocardial calcification by computed tomography (CT); (iii) adequate description of patients, including their chief complaint, medical history, evaluations, and treatments; and (iv) publication in English. Among the 75 patients, 24 had sepsis, 14 had myocarditis, and 37 had other pathologies. The mortality rate was 33% for patients with sepsis, 14% for patients with myocarditis, and 11% for patients with other pathologies. Follow-up CT findings beyond 2 years were reported in six patients, showing that the CT findings of myocardial calcification persisted but subsided over time. Autopsy was performed in seven patients, and extensive interstitial fibrosis and collection of inflammatory cells were observed in patients with myocarditis, sepsis, and ischaemic heart disease. Conclusion: While various medical conditions can cause myocardial calcification, accompanying conditions commonly reported with myocardial calcification were sepsis and myocarditis. The CT findings of myocardial calcification tend to regress over time if the underlying disease can be treated.

Impact of the Aortomitral Positional Anatomy on Atrioventricular Conduction Disorder Following Mitral Valve Surgery.

BACKGROUND: Variations in the aortomitral positional anatomy, including aortic root rotation appear to be related to variations in the location of the conduction system, including the bundle of His. However, little is known about their clinical significance. METHODS AND RESULTS: This study included 147 patients with normal ECGs who underwent mitral valve surgery. The aortomitral anatomy was classified using preoperative 3-dimensional transesophageal echocardiography, and postoperative conduction disorders, including atrioventricular block and bundle branch block, were analyzed. Variations classified as aortomitral appearance were designated as having a center appearance (85.7%, n=126/147) or lateral appearance (14.3%, n=21/147) on the basis of whether the aortic root was located at the center or was shifted to the left fibrous trigone side. Subsequently, those with a center appearance, aortic root rotation was classified as having a center rotation (83.3% [n=105/126]), in which the commissure of the left and noncoronary aortic leaflet was located at the center, lateral rotation (14.3% [n=18/126]), rotated to the left trigone side, or medial rotation (2.4% [n=3/126]), rotated to the right. The incidence of 3-month persistent new-onset conduction disorder was higher in the lateral appearance than the center appearance group (21.1% versus 5.0%; P=0.031) and higher in the lateral rotation than in the center or medial rotation groups (29.4% versus 1.0% versus 0.0%, respectively; P<0.001). CONCLUSIONS: Aortomitral variations can be classified using 3-dimensional transesophageal echocardiography. Lateral appearance and lateral rotation are risk factors for conduction disorders in mitral valve surgery.

The foremost and greatest barrier to end-stage heart failure treatment: the impact of caregiver shortage.

We examined the number of patients abandoning cardiac replacement therapy due to the inability to secure a designated caregiver. At Osaka University Hospital Heart Center, when we receive a consultation for a patient with severe heart failure from another hospital, a heart failure team makes a visit to the referring hospital as soon as possible. We retrospectively analyzed this hospital-visit database. We received 199 severe heart failure consultations from 2016-2023. Issues identified during hospital visits included age ≥ 65 years (8%), inability to confirm the patient's intention (8.5%), and explicit refusal of therapy (2.5%). Medical problems included multiple organ failure (18.1%), obesity (13.1%), diabetes (9.5%), malignancy (5.5%), chronic dialysis (1.0%), and other systemic diseases (12.6%). Adherence problems included poor medication compliance (3.5%), history of heavy drinking (2.5%), and smoking (2.0%). Social problems included inadequate family support in 16.1% of patients. Of the 199 patients, 95 (48.0%) proceeded to a heart transplant and LVAD indication review meeting at Osaka University Hospital. The remaining 104 patients (52.0%) did not proceed to the meeting. Reasons included improvement of heart failure with conservative treatment in 37 cases (35.6%), death before discussion in 21 cases (20.2%), medical contraindications in 18 cases (18.3%), lack of caregivers in 18 cases (18.3%; 9.5% of 199 cases), and patient refusal in 5 cases (4.8%). Approximately 10% of patients consulted at Osaka University Hospital Heart Center for severe heart failure abandoned cardiac replacement therapy due to the lack of caregivers.

A risk model of mortality rate in dialysis patients following transcatheter aortic valve replacement.

BACKGROUND: Dialysis patients undergoing transcatheter aortic valve replacement (TAVR) generally have poor prognosis compared with non-dialysis patients. Furthermore, there are few reliable risk models in this clinical setting. Therefore, we aimed to establish a risk model in dialysis patients undergoing TAVR that would be informative for their prognosis and the decision-making process of TAVR. METHODS: A total 118 dialysis patients (full cohort) with severe aortic stenosis underwent TAVR in our institute between 2012 and 2022. The patients of the full cohort were randomly assigned to two groups in a 2:1 ratio to form derivation and validation cohorts. Risk factors contributing to deaths were analyzed from the preoperative variables and a risk model was established from Cox proportional hazard model. RESULTS: There were 69 deaths following TAVR derived from infectious disease (43.5 %), cardiovascular-related disease (11.6 %), cerebral stroke or hemorrhage (2.9 %), cancer (1.4 %), unknown origin (18.8 %), and others (21.7 %) during the observational period (811 ±â€¯719 days). The cumulative overall survival rates using the Kaplan-Meier method at 1 year, 3 years, and 5 years in the full cohort were 82.8 %, 41.9 %, and 24.2 %, respectively. An optimal risk model composed of five contributors: peripheral vascular disease, serum albumin, left ventricular ejection fraction < 40 %, operative age, and hemoglobin level, was established. The estimated C index for the developed models were 0.748 (95 % CI: 0.672-0.824) in derivation cohort and 0.705 (95 % CI: 0.578-0.832) in validation cohort. The prediction model showed good calibration [intraclass correlation coefficient = 0.937 (95%CI: 0.806-0.981)] between actual and predicted survival. CONCLUSIONS: The risk model was a good indicator to estimate the prognosis in dialysis patients undergoing TAVR.

Temporal recovery and prognostic factors for dysphagia following cardiovascular surgery: Retrospective analysis and development of predictive score.

OBJECTIVE: Dysphagia is a common complication associated with cardiovascular surgery (CVS). This study sought to better understand recovery timelines, identify risk factors, and create a prognostic model for oral intake restoration. METHODS: This retrospective study included 134 patients who had CVS between April 2022 and March 2024. We assessed swallowing ability through fiberoptic endoscopic evaluation of swallowing (FEES). We randomly divided the patients' data into a training dataset and a test dataset in a ratio of 70/30 and Kaplan-Meier analyses and Cox regression were used to assess predictors of total oral intake. We also created a scoring system using the estimated regression coefficients. RESULTS: Most patients with CVS achieved total oral intake in 7-11 days after extubation. Over 168 h of intubation, the presence of penetration or aspiration, a poor FEES score (score > 6), and perioperative complications were significant risk factors for delayed total oral intake. The predicting score was calculated by adding the scores for each individual factor, including FEES score, penetration/aspiration, and preoperative complications. Scores ranged 0-8, categorizing patients into 0-2, 3-5, and 6-8 groups, clearly demonstrating that the higher the predicting score, the longer the time to total oral intake in both the training and the test dataset. CONCLUSIONS: All risk factors for unsuccessful or delayed total oral intake were intubation for more than a week, poor swallowing ability, and the presence of perioperative complications. The scoring system accurately predicts the restoration of oral intake following CVS.

The impact of angiographic pedal circulation status on wound healing in chronic limb-threatening ischemia after bypass surgery.

OBJECTIVES: In the treatment of chronic limb-threatening ischemia (CLTI), complete wound healing is an important goal. Although foot perfusion status seems to be important for wound healing, the global limb anatomic staging system (GLASS) of the Global Vascular Guidelines (GVG) does not include pedal artery status for the staging process due to the lack of sufficient evidence of its importance. This study aimed to clarify the importance of pedal perfusion status after bypass surgery. METHODS: Among the 153 CLTI cases that underwent bypass distal to popliteal arteries from 2014 to 2018, 117 CLTI limbs with wounds and with sufficient pedal angiographic data were enrolled. They were classified into two groups, based on the wound status 6 months postoperatively; early wound healing group (EWG, N=78), which achieved complete wound healing within 6 months postoperatively, and prolonged healing or unhealed wounds group (PWG, N=39), which failed to achieve wound healing within 6 months. Various factors associated with wound healing, including the wound, ischemia, and foot infection (WIfI) classification, intraoperative graft flow, and pedal angiographic data, were analyzed. Regarding pedal angiographic data, in addition to the GLASS inframalleolar/pedal disease descriptor (IPD), newly formed classification system of the pedal circulation status in association with the location of wounds was included: pedal circulation status was classified into two groups as visualized arterial perfusion towards wounds (visualized perfusion) and non-visualized arterial perfusion towards wounds (non-visualized perfusion). RESULTS: Univariate analysis showed preoperative albumin (Odds ratio [OR], 0.47; 95% confidence interval [CI], 0.24-0.94; P=.027), higher WIfI clinical stage (OR, 3.88; 95%CI, 1.74-10.1; P=.0005), higher IPD (OR, 2.16; 95%CI, 1.16-4.02; P=.012), and non-visualized perfusion to wounds (OR, 5.74: 95%CI, 2.45-14.0; P < .0001) as significant for prolonged wound healing. Multivariate analysis showed higher WIfI stage (OR, 5.04; 95%CI, 1.74-14.6; P=.0029) and non-visualized perfusion to wounds (OR, 4.34; 95%CI, 1.71-11.0; P=.0021) as significant, while IPD was not detected as significant. Regarding blood supply to the foot, although graft flow was significantly lower in IPD-P2 than IPD-P0/P1, graft flow was similar regardless of the status of angiographic circulation to wounds, suggesting that distribution of blood supply to the wound would be more important than total amount of blood supply to the foot for wound healing. CONCLUSIONS: WIfI clinical stage and pedal circulatory environment were important factors for wound healing after bypass surgery. Pedal anatomical classification system including perfusion status would be important for decision making in CLTI treatment.

Prospective evaluation of automated vascular analysis for ilio-femoral artery lesions before and after percutaneous endovascular aortic repair.

BACKGROUND: This study was conducted to evaluate the differences between pre- and postoperative access conditions in percutaneous endovascular aortic repair (PEVAR). METHODS: Between December 2021 and October 2023, PEVAR was performed on 61 patients using the Perclose ProStyle (Abbott Vascular). Enhanced computed tomography and ankle-brachial index tests were performed preoperatively and postoperatively. The inner diameter and area of the iliofemoral artery were automatically measured, and the pre- and postoperative values were compared (114 legs). The same analysis was performed on 12 legs with previous groin operations; open surgical EVAR was performed in 9 legs, an endarterectomy of the femoral artery in 1, and a femoropopliteal bypass in the other leg. RESULTS: All patients were discharged without surgical site infections, lymphatic fistulas, or retroperitoneal haematomas. There were no significant differences between the pre-and postoperative inner diameter and inner area of the external iliac artery and common femoral artery. There were no significant differences between the preoperative and postoperative ankle-brachial index tests. In 12 legs with a previous groin operation, the postoperative ankle-brachial index tests and inner diameter and area of the external iliac artery and common femoral artery were statistically equal to the preoperative values. CONCLUSIONS: This study can support the safety of percutaneous endovascular aortic repair, even in patients with redo groin operations.

Delayed peak antibody titers after the second dose of SARS-CoV-2 vaccine in solid organ transplant recipients: Prospective cohort study.

Poor post-vaccination production of antibody against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a concern among solid organ transplant (SOT) recipients. Furthermore, the timing and kinetics of antibody titers after the second vaccine dose are unknown. We conducted a multicenter prospective observational study that included 614 SOT recipients: 460 kidney, 53 heart, 50 liver, 20 lung, and 31 simultaneous pancreas-kidney (SPK). The participants received two doses of the mRNA vaccine (Pfizer BNT162b2 or Moderna mRNA-1273), as indicated. Serum samples were collected before the first and second vaccinations and at 1, 3, and 6 months after the second vaccine dose, which were then assessed for SARS-CoV-2 antibodies. The overall seropositivity rate was 43% at 1 month after administration of the second vaccine dose; it gradually increased to 68% at 3 months after second dose administration and to 70% at 6 months. In addition, recipient of kidney, lung or SPK transplants had lower antibody titers at the 3- and 6-month time points than did the other recipients. SOT recipients acquired SARS-CoV-2 S-IgG antibodies slowly, and the peak titer differed significantly from that of the general population.

A case of truncus arteriosus with severe heart failure and pulmonary stenosis: bridge to transplant candidacy with surgical correction and a ventricular-assist device.

Ventricular-assist device therapy for small patients with congenital heart disease is challenging due to its complex anatomy and hemodynamics. We describe a 3-year-old patient with heart failure with truncus arteriosus in the palliative stage. The patient underwent palliative right ventricular outflow tract reconstruction following bilateral pulmonary artery banding. At 6 months of age, the patient developed severe truncal valve regurgitation and left ventricular dysfunction. Emergent truncal valve replacement with a mechanical valve was performed, but left ventricular dysfunction persisted. At 3 years of age, the patient developed acute progression of heart failure triggered by influenza infection. The patient was intubated and transferred to our center to determine the indication for heart transplantation. On the second day after admission, signs of multiorgan failure appeared. Emergent ventricular-assist device implantation for both ventricles was performed with truncal valve closure, ventricular septal defect closure, atrial septal defect closure, and re-right ventricular outflow tract reconstruction. The right ventricular-assist device was successfully removed on the seventh postoperative day. Due to the small pulmonary arteries, severe pulmonary stenosis persisted after ventricular-assist device implantation, but it gradually improved with multiple pulmonary angioplasties. The patient was registered in the Japanese organ transplant network and is awaiting a donor organ in a stable condition.

Recurrent Pericardial Effusion Resulting From Right Ventricular Free Wall Injury Caused by Leadless Pacemaker Tines.

An 87-year-old man developed delayed cardiac tamponade 55 min after leadless pacemaker implantation and recurrent pericardial effusion 20 days later. Electrocardiogram-gated enhanced cardiac computed tomography revealed that the leadless pacemaker tines on the lateral side had penetrated the right ventricular free wall. He underwent off-pump hemostatic surgery.

Skeletal Myoblast Cells Enhance the Function of Transplanted Islets in Diabetic Mice.

Islet transplantation (ITx) is an established and safe alternative to pancreas transplantation for type 1 diabetes mellitus (T1DM) patients. However, most ITx recipients lose insulin independence by 3 years after ITx due to early graft loss, such that multiple donors are required to achieve insulin independence. In the present study, we investigated whether skeletal myoblast cells could be beneficial for promoting angiogenesis and maintaining the differentiated phenotypes of islets. In vitro experiments showed that the myoblast cells secreted angiogenesis-related cytokines (vascular endothelial growth factor (VEGF), hepatocyte growth factor (HGF), and stromal-derived factor-1α (SDF-1α)), contributed to maintenance of differentiated islet phenotypes, and enhanced islet cell insulin secretion capacity. To verify these findings in vivo, we transplanted islets alone or with myoblast cells under the kidney capsule of streptozotocin-induced diabetic mice. Compared with islets alone, the group bearing islets with myoblast cells had a significantly lower average blood glucose level. Histological examination revealed that transplants with islets plus myoblast cells were associated with a significantly larger insulin-positive area and significantly higher number of CD31-positive microvessels compared to islets alone. Furthermore, islets cotransplanted with myoblast cells showed JAK-STAT signaling activation. Our results suggest two possible mechanisms underlying enhancement of islet graft function with myoblast cells cotransplantation: "indirect effects" mediated by angiogenesis and "direct effects" of myoblast cells on islets via the JAK-STAT cascade. Overall, these findings suggest that skeletal myoblast cells enhance the function of transplanted islets, implying clinical potential for a novel ITx procedure involving myoblast cells for patients with diabetes.

In vivo mitral valve repair for the transplanted donor heart in orthotopic heart transplantation.

A 53-year-old woman with the dilated phase of hypertrophic cardiomyopathy underwent orthotopic heart transplantation. The donor heart was evaluated as normal preoperatively without mitral regurgitation or the left atrium dilation, transplanted using the modified bicaval technique. Although the heart beat satisfactorily after aortic declamping, massive mitral regurgitation was observed without any prolapse or annular dilation. Because of the difficulty in weaning from cardiopulmonary bypass, a second aortic cross-clamp was applied, and we detached the inferior vena cava and the right side of the left atrial anastomosis to approach the mitral valve, obtaining a satisfactory exposure. No abnormalities were observed in the mitral valve leaflets, annulus or subvalvular apparatus. Subsequent in vivo mitral annuloplasty using prosthetic full ring successfully controlled the regurgitation, and the patient was easily weaned from cardiopulmonary bypass. She discharged to home with good mitral valve and cardiac functions. And the patient has been doing well without any recurrence of MR or heart failure for over a year after surgery.

Development of composite functional tissue sheets using hiPSC-CMs and hADSCs to improve the cardiac function after myocardial infarction.

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have been widely used in therapy of ischemic heart disease. However, there are still remaining issues that limit the therapeutic efficacy, such as immune rejection and low retention of hiPSC-CMs. Human adipose mesenchymal stromal cells (hADSCs) have been reported to be able to regulate the immune response, promote angiogenesis and promote the maturation of hiPSC-CMs. In this study, we co-cultured these two types of cells on fiber scaffold made of biodegradable poly (D,L-lactic-co-glycolic acid) (PLGA) polymer for several days to develop a composited 3D cardiac tissue sheet. As expected, the cells formed 231.00 ± 15.14 µm thickness tissue, with improved organization, alignment, ECM condition, contractile ability, and paracrine function compared to culture hiPSC-CMs only on PLGA fiber. Furthermore, the composited 3D cardiac tissue sheet significantly promoted the engraftment and survival after transplantation. The composited 3D cardiac tissue sheet also increased cardiac function, attenuated ventricular remodeling, decreased fibrosis, and enhanced angiogenesis in rat myocardial infarction model, indicating that this strategy wound be a promising therapeutic option in the clinical scenario.

How should cardiac xenotransplantation be initiated in Japan?

The world's first clinical cardiac xenotransplantation, using a genetically engineered pig heart with 10 gene modifications, prolonged the life of a 57-year-old man with no other life-saving options, by 60 days. It is foreseeable that xenotransplantation will be introduced in clinical practice in the United States. However, little clinical or regulatory progress has been made in the field of xenotransplantation in Japan in recent years. Japan seems to be heading toward a "device lag", and the over-importation of medical devices and technology in the medical field is becoming problematic. In this review, we discuss the concept of pig-heart xenotransplantation, including the pathobiological aspects related to immune rejection, coagulation dysregulation, and detrimental heart overgrowth, as well as genetic modification strategies in pigs to prevent or minimize these problems. Moreover, we summarize the necessity for and current status of xenotransplantation worldwide, and future prospects in Japan, with the aim of initiating xenotransplantation in Japan using genetically modified pigs without a global delay. It is imperative that this study prompts the initiation of preclinical xenotransplantation research using non-human primates and leads to clinical studies.

CD8+ T cell-mediated rejection of allogenic human-induced pluripotent stem cell-derived cardiomyocyte sheets in human PBMC-transferred NOG MHC double knockout mice.

BACKGROUND: Transplantation of human-induced pluripotent stem cell-derived cardiomyocytes (hiPS-CMs) has emerged as a promising therapy to treat end-stage heart failure. However, the immunogenicity of hiPS-CMs in transplanted patients has not been fully elucidated. Thus, in vivo models are required to estimate immune responses against hiPS-CMs in transplant recipients. METHODS: We transferred human peripheral blood mononuclear cells (hPBMCs) into NOD/Shi-scid IL-2rgnull (NOG) MHC class I/II double knockout (NOG-ΔMHC) mice, which were reported to accept hPBMCs without xenogeneic-graft-versus-host disease (xeno-GVHD). Then, hiPS-CM sheets generated from the hiPS cell line 201B7 harboring a luciferase transgene were transplanted into the subcutaneous space of NOG-ΔMHC mice. Graft survival was monitored by bioluminescent images using a Xenogen In Vivo Imaging System. RESULTS: The human immune cells were engrafted for more than 3 months in NOG-ΔMHC mice without lethal xeno-GVHD. The hiPS-CMs expressed a moderate level of human leukocyte antigen (HLA)-class I, but not HLA-class II, molecules even after interferon-gamma (IFN-γ) stimulation. Consistently, the allogenic IFN-γ-treated hiPS-CMs induced weak CD8+ but not CD4+ T cell responses in vitro. hiPS-CM sheets disappeared approximately 17 to 24 days after transplantation in hPBMC-transferred NOG-ΔMHC mice, and CD8+ T cell depletion significantly prolonged graft survival, similar to what was observed following tacrolimus treatment. CONCLUSIONS: hiPS-CMs are less immunogenic in vitro but induce sufficient CD8+ T cell-mediated immune responses for graft rejection in vivo.

Application of a laparoscopic device for cell-derived sheet transplantation on the liver in a porcine model.

BACKGROUND: Cell-derived sheets are of global interest for regenerative therapy. Transplanting a sheet for abdominal organs requires a device for laparoscopic delivery to minimize invasiveness. Here, using a porcine model, we aimed to confirm the feasibility of a device developed to deliver sheets to the thoracic cavity in a laparoscopic transplantation procedure. MATERIAL AND METHODS: We used the device to transplant human skeletal myoblast cell sheets onto the liver and measured extra-corporeal, intra-abdominal, and total procedure times for sheet transplantation. Tissues, including the liver and the sheet, were collected two days after transplantation and analyzed histologically. RESULTS: In all experiments (n = 27), all sheets were successfully placed at target locations. The mean (± standard deviation) extra-corporeal, intra-abdominal, and total procedure times were 44 ± 29, 33 ± 12, and 77 ± 36 s, respectively. We found no difference between the two surgeons in procedure times. Histological analyses showed no liver damage with the transplantation and that sheets were transplanted closely onto the liver tissue without gaps. CONCLUSION: We confirmed the feasibility of a simple universal device to transplant cell-derived sheets via laparoscopic surgery. This device could support a minimally invasive procedure for sheet transplantation.

Advance care planning in the treatment of implantable left ventricular assist device: a republication of the review published in Japanese Journal of Artificial Organs.

Advance care planning (ACP) is essential in managing serious and chronic illnesses to ensure that patients receive care aligned with their personal values, goals, and preferences. This review focuses on integrating ACP in the treatment of patients receiving implantable left ventricular assist devices (VADs). The heart failure palliative care team developed a unique advance directive form and pamphlet to facilitate ACP discussions, emphasizing not only medical treatment preferences but also patients' values and life goals.The study highlights the distinction between bridge to transplantation (BTT) and destination therapy (DT) in VAD patients, with different goals and considerations for ACP. The use of decision aids developed especially for DT candidates as a communication tool helps in sharing patients' wishes and facilitates shared decision-making, particularly in the complex decisions surrounding DT therapy.Challenges in implementing ACP, such as time constraints due to urgent medical conditions, difficulties in patient communication, and the recent COVID-19 pandemic, are addressed. The need for a comprehensive healthcare system capable of supporting patients' ACP wishes, especially in the community setting, is also pointed out.Future directions include not only developing materials to ease ACP discussions and ensuring that ACP content is shared among healthcare providers to foster collaborative and detailed planning, but also a call for widespread adoption of ACP in Japan.This is a translation of a paper written in Japanese Journal of Artificial Organs (Vol. 52, No. 1, pp. 89-92) with additions and corrections.

Feasibility of an animal model for long-term mechanical circulatory support with Impella 5.5 implanted through carotid artery access in sheep.

Impella is a mechanical circulatory support device of a catheter-based intravascular microaxial pump for left ventricular support and unloading. However, nonclinical studies assessing the effects of the extended duration of left ventricular unloading on cardiac recovery are lacking. An animal model using Impella implanted with a less invasive procedure to enable long-term support is required. This study aimed to evaluate the feasibility of an animal model for long-term support with Impella 5.5 implanted through carotid artery access in sheep.Impella 5.5 was implanted in four sheep through the proximal region of the left carotid artery without a thoracotomy, and myocardial injuries were induced by coronary microembolization. Support by Impella 5.5 was maintained for 4 weeks, and the animals were observed. The position of Impella 5.5 and cardiac function was evaluated using cardiac computer tomography at 2 and 4 weeks after implantation.All four animals completed the 4-week study without major complications. The discrepancy in the Impella 5.5 flow rate between the conscious and anesthetized states was observed depending on the device's position. Animals in whom the inflow was above the left ventricular papillary muscle had a relatively high flow rate under the maximum performance level without a suction alarm during the conscious state. Pathological changes in the aortic valve were observed. Cardiac function under the minimum performance level was observed with no remarkable deterioration.The animal model with myocardial injuries supported for 4 weeks by Impella 5.5 implanted through carotid artery access in sheep was feasible.