Futuristic perspectives: novel MCS devices.

Treatment of heart failure needs a firm understanding of anatomy and physiology of the circulatory system and the heart. Ancient India takes credit for the "modern concepts" of human circulation. This short review encompasses futuristic perspectives on mechanical circulatory devices (MCS). The heart is a complex structure which has evolved over millennia both in its structure and mechanical functionality. Evolving from a simple tube with peristaltic action such as in annelids, it evolved rapidly to form a more complexity as animals evolved from oceanic to terrestrial adaptation. The major advance is the innovation of placing the actuation mechanism within the blood flow path, such as in continuous flow technology (axial or centrifugal) when contrasted to the positive displacement pumps. We present novel concepts but also touch upon what we would consider as fundamental problems or paradigms that need to be addressed to move this field ahead. Finally, we propose what would be termed a "futuristic" MCS device.

Off-pump surgical thrombectomy for subacute right atrial thrombus: A case report.

Right heart thrombi can be seen in a minority of patients with acute pulmonary embolism and are associated with an increased mortality risk. The optimal treatment option comprises thrombolysis or surgical thrombectomy either with catheterbased interventions or with open surgery. Open right atrial thrombectomy is usually performed under cardiopulmonary bypass due to the need for concomitant pulmonary embolectomy. Nevertheless, cardiopulmonary bypass has major drawbacks such as the risk of stroke, coagulopathy, and myocardial and respiratory dysfunction, particularly in high-risk patients. Herein, we report a case of successful off-pump surgical thrombectomy performed for the right atrial clot-in-transit following failure of the catheter-based intervention.

The Use of Extracorporeal Membrane Oxygenation as a Bridge to Bone Marrow Transplantation in a Patient With High-risk Acute Myeloid Leukemia.

An 18-year-old girl with high-risk acute myeloid leukemia developed Streptococcus mitis septic shock and multiorgan dysfunction syndrome, including biventricular failure. Due to the anticipated reversibility of her cardiogenic shock, her young age, and her favorable survival chance after an allogeneic hematopoietic stem cell transplant, she was placed on full circulatory support with venoarterial extracorporeal membrane oxygenation as a bridge to her successful hematopoietic stem cell transplantation 2 months later. This highlights the importance of prognostication in patient selection for extracorporeal life support. A multidisciplinary approach is essential to each case until more definite initiation criteria, risk stratification, and treatment protocols are established.

Resonantly Coupled High-Efficiency Sensors for Assessment of Ventricular Chamber Size for Autonomous Control of Left Ventricular Assist Device.

Current left ventricular assist devices (LVADs) are set to a fixed rpm and are unable to adjust to physiological demands irrespective of preload or afterload. Autonomous control of LVADs has the potential to reduce septal shift, preserve right ventricle function, and meet physiological demands. A highly innovative resonantly coupled regimen is presented which can achieve this goal. We introduce sensors based on a highly sensitive relationship between transmission coefficient and spatial separation in a resonantly coupled regimen. This relationship represents a polynomial regression. A regimen of an apical sensor and multiple outflow sensors is investigated. A range of separations varying from 50-200 mm was systematically investigated. These ranges consider anatomical & physiological variation(s) in cardiac chamber size. Validation was obtained in porcine heart preparation. The polynomial regression model predicted distance between the sensors with a mean absolute percentage error of 0.77%, 1.07%, and 5.75% for the three putative positions of the outflow sensors and apical sensor when compared with experimental results. A high degree of accuracy (95%) between the predicted and observed distance was obtained. Continuous measurements were done over 90 days to examine drift, with no statistically detectable change in measurements over million sampling cycles. We have demonstrated a reliable sensor methodology without drift for assessing ventricular chamber size in an LVAD setup. This has the potential to allow autonomous control of LVAD based on ventricular chamber size to address some of the adverse events.

Shoelace technique for the management of deep sternal wound infection.

In this article, we describe a practical technique of managing deep sternal wound infection by combining two dynamic wound closure methods, namely gradual approximation of the wound edges using vessel loops: the shoelace technique and the vacuumassisted closure system.

Machine Learning in Cardiac Surgery: Predicting Mortality and Readmission.

Predicting outcomes in open-heart surgery can be challenging. Unexpected readmissions, long hospital stays, and mortality have economic implications. In this study, we investigated machine learning (ML) performance in data visualization and predicting patient outcomes associated with open-heart surgery. We evaluated 8,947 patients who underwent cardiac surgery from April 2006 to January 2018. Data visualization and classification were performed at cohort-level and patient-level using clustering, correlation matrix, and seven different predictive models for predicting three outcomes ("Discharged," "Died," and "Readmitted") at binary level. Cross-validation was used to train and test each dataset with the application of hyperparameter optimization and data imputation techniques. Machine learning showed promising performance for predicting mortality (AUC 0.83 ± 0.03) and readmission (AUC 0.75 ± 0.035). The cohort-level analysis revealed that ML performance is comparable to the Society of Thoracic Surgeons (STS) risk model even with limited number of samples ( e.g. , less than 3,000 samples for ML versus more than 100,000 samples for the STS risk models). With all cases (8,947 samples, referred as patient-level analysis), ML showed comparable performance to what has been reported for the STS models. However, we acknowledge that it remains unknown at this stage as to how the model might perform outside the institution and does not in any way constitute a comparison of the performance of the internal model with the STS model. Our study demonstrates a systematic application of ML in analyzing and predicting outcomes after open-heart surgery. The predictive utility of ML in cardiac surgery and clinical implications of the results are highlighted.

Echocardiography fails to detect an extensive aortic root abscess in a patient with infective endocarditis: a case report.

Background: Echocardiography plays a central role in the diagnosis of infective endocarditis (IE). In recent years, additional imaging techniques have begun to challenge the conventional approach. We present a case where the use of transthoracic/transoesophageal echocardiography (TTE/TOE) in suspected IE failed to identify an extensive periannular abscess, later identified by 18F-flurodeoxyglucose-positron emission tomography (FDG-PET), requiring urgent intervention. Case summary: A 69-year-old man with symptomatic Streptococcus sanguinis bacteraemia and a bicuspid aortic valve was found to have new-onset left bundle branch block that progressed to complete heart block. After starting on IV Penicillin G and having a temporary pacemaker inserted, his clinical condition improved. Transthoracic echocardiography and TOE showed no evidence of abscess. However, persistent first-degree atrioventricular block raised clinical suspicion of a possible extended infection. Subsequent FDG-PET revealed focal activity around the aortic root that extended inferiorly into the interatrial septum, consistent with active infection and possible abscess. Composite aortic root replacement with insertion of a mechanical prosthesis was carried out, revealing extensive IE and multiple periannular abscesses. Discussion: As guidelines grapple with evolving understandings of how best to define the optimal imaging approach for the management of complicated IE, the results of this case clearly show the importance of heightened clinical suspicion and need for prompt operative intervention when faced with patients who present with predisposing conditions and concern for advanced conduction disease. Clinicians and researchers are encouraged to learn from the potential near-miss of an extensive periannular abscess to help guide guideline-development of imaging in complicated IE and prevent adverse outcomes in patients with similar presentations.

First Transfemoral Implantation of a Novel Transcatheter Valve in an LVAD Patient With Aortic Insufficiency.

An 80-year-old man with a destination left ventricular assist device (LVAD) presented with decompensated heart failure. Evaluation demonstrated numerous LVAD high power spike events, significant aortic regurgitation, and hemolysis. He underwent successful aortic valve replacement with a novel transcatheter valve and LVAD pump exchange that resulted in an improvement in his clinical status. (Level of Difficulty: Advanced.).

Delayed presentation of bone cement implantation syndrome requiring extracorporeal membrane oxygenation support.

Bone cement implantation syndrome is a rare and potentially fatal complication which may occur following cemented bone surgery. Herein, we present a case of delayed and fatal presentation of bone cement implantation syndrome following cemented spinal surgery, despite mechanical support with extracorporeal mechanical oxygenation.

Pharyngo-esophago-gastric dysmotility in intubated patients: A comprehensive review.

Postextubation swallowing dysfunction is a common phenomenon within the pharyngo-esophago-gastric dysmotility disorders. It is commonly seen after major surgery which requires endotracheal intubation for mechanical ventilation and associated with pulmonary complications which may lead to increased morbidity and mortality, prolonged hospital stay and increased cost. Thus, understanding the underlying mechanism of this phenomenon is crucial for early recognition and diagnosis of this entity, and to take preventive measures to minimize associated complications and morbidity. Literature search of the Medline database was performed to obtain related studies discussing pharyngo-esophago-gastric dysmotility. We focused on studies including PSD following major surgery and extracted data from the relevant studies, compared results, and summarized the related information. We reviewed the underlying mechanism, available diagnostic tools, risk factors, major pulmonary complications and their consequences, basic preventive measures and potential solutions related to this entity and aimed to guide physicians through decision-making process for their individual patients.

Telemedicine in the era of coronavirus 19: Implications for postoperative care in cardiac surgery.

BACKGROUND: The Coronavirus 19 (COVID-19) pandemic forced an unprecedented shift of postoperative care for cardiac surgery patients to telemedicine. How patients and surgeons perceive telemedicine is unknown. We examined patient and provider satisfaction with postoperative telehealth visits following cardiac surgery. METHODS: Between April 2020 and September 2020, patients who underwent open cardiac surgery and had a postoperative appointment via telemedicine were administered a patient satisfaction survey over the phone. Time of survey administration ranged from 1 to 4 weeks following their appointment. Surgeons also completed a satisfaction survey following each telemedicine appointment they conducted. RESULTS: Fifty patients were surveyed. Of these, 36 (72%) had a postoperative appointment over the telephone, and 14 (28%) had a postoperative appointment via video-chat. Overall, patients expressed satisfaction with the care that they received via our two telemedicine modalities (mean Likert scale agreement 4.8, SD 0.5). Despite this, 46% of patients said they would prefer their next postoperative appointment to be via telemedicine even if there was not a stay-at-home order in place. All surgeons surveyed reported (agree/strongly agree) that they would prefer to see their postoperative patients using telemedicine. CONCLUSIONS: These findings highlight acceptability of continuing telemedicine use in the postoperative care of cardiac surgery patients.

Impact of Preoperative Lymphopenia on Survival Following Left Ventricular Assist Device Placement.

Lymphopenia has been implicated in poor outcomes in the heart failure population. However, the prognostic implication of lymphopenia in left ventricular assist device (LVAD) patients is unknown. We examine the impact of lymphopenia on all-cause mortality in this population over a 24-month period post-implantation. A total of 170 patients between June 2011 and July 2018 receiving permanent durable LVAD at a single center formed the study population. Criteria for lymphopenia on admission, defined as an absolute lymphocyte count (ALC) <1500 cells/µl, was met in 99 patients. A total of 11 patients were excluded: two with ALC >4800/µl and nine with incomplete data. Survival across groups was compared with a Kaplan-Meier plot and log-rank statistics. The Cox proportional hazard model was used to examine the association between lymphopenia and 24-month all-cause mortality. In the lymphopenia group, mean ALC was 909.6 ± 331.9 versus 2073.6 ± 501.1 in the non-lymphopenic group. Twenty-four-month all-cause mortality was significantly higher in the lymphopenia group (p = 0.009). The lymphopenic patients had worse unadjusted (hazard ratio [HR] = 2.14, confidence interval [CI] = 1.19-3.82; p = 0.01) and adjusted survival (HR = 2.07, CI = 1.13-3.79; p = 0.02). Further clinical investigations are required to assess the utility of continued clinical monitoring of ALC levels beyond LVAD placement.

Biologically Inspired, Open, Helicoid Impeller Design for Mechanical Circulatory Assist.

Rotating impeller actuated by electromagnet has been a key technological innovation which surpassed earlier limitations of pulsatile pumps. Current impeller design, however, is alien to the functional unit of the human circulatory system and remains a potential cause of adverse prothrombotic events such as hemolysis or pump thrombosis by forcing blood cells to pass over a narrow space available within the rapidly alternating blades attached along its central hub, creating fundamentally a nonphysiologic flow, especially for miniaturized percutaneous blood pumps. Here, we present a biologically inspired, open, helicoid (BiO-H) impeller design for a circulatory assist device that has a fundamentally different footprint from the conventional Archimedean screw-based impeller designs by implementing new design features inspired by an avian right atrioventricular valve. Design parameters including an inner diameter, helix height, overall height, helix revolutions/pitch, blade length, blade thickness, introductory blade angle, number of blades, and blade shape were optimized for maximum output volumetric flow rate through the parametric analysis in computational fluid dynamics simulation. BiO-H shows an improved flow path with 2.25-fold less cross-sectional area loss than the conventional impeller designs. BiO-H with a diameter of 15 mm resulted in a maximum flow rate of 25 L/min at 15,000 revolutions per minute in simulation and showed further improved pressure-flow relationship in benchtop experiments. The design shows promise in increasing flow and could serve as a new impeller design for future blood pumps.

Association of Clinical Outcomes With Left Ventricular Assist Device Use by Bridge to Transplant or Destination Therapy Intent: The Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3 (MOMENTUM 3) Randomized Clinical Trial.

Importance: Left ventricular assist devices (LVADs) are well established in the treatment of advanced heart failure, but it is unclear whether outcomes are different based on the intended goal of therapy in patients who are eligible vs ineligible for heart transplant. Objective: To determine whether clinical outcomes in the Multicenter Study of MagLev Technology in Patients Undergoing Mechanical Circulatory Support Therapy With HeartMate 3 (MOMENTUM 3) trial differed by preoperative categories of bridge to transplant (BTT) or bridge to transplant candidacy (BTC) vs destination therapy (DT). Design, Setting, and Participants: This study was a prespecified secondary analysis of the MOMENTUM 3 trial, a multicenter randomized clinical trial comparing the magnetically levitated centrifugal-flow HeartMate 3 (HM3) LVAD to the axial-flow HeartMate II (HMII) pump. It was conducted in 69 centers with expertise in managing patients with advanced heart failure in the United States. Patients with advanced heart failure were randomized to an LVAD, irrespective of the intended goal of therapy (BTT/BTC or DT). Main Outcomes and Measures: The primary end point was survival free of disabling stroke or reoperation to remove or replace a malfunctioning device at 2 years. Secondary end points included adverse events, functional status, and quality of life. Results: Of the 1020 patients with implants (515 with HM3 devices [50.5%] and 505 with HMII devices [49.5%]), 396 (38.8%) were in the BTT/BTC group (mean [SD] age, 55 [12] years; 310 men [78.3%]) and 624 (61.2%) in the DT group (mean [SD] age, 63 [12] years; 513 men [82.2%]). Of the patients initially deemed as transplant ineligible, 84 of 624 patients (13.5%) underwent heart transplant within 2 years of LVAD implant. In the primary end point analysis, HM3 use was superior to HMII use in patients in the BTT/BTC group (76.8% vs 67.3% for survival free of disabling stroke and reoperation; hazard ratio, 0.62 [95% CI, 0.40-0.94]; log-rank P = .02) and patients in the DT group (73.2% vs 58.7%; hazard ratio, 0.61 [95% CI, 0.46-0.81]; log-rank P < .001). For patients in both BTT/BTC and DT groups, there were not significantly different reductions in rates of pump thrombosis, stroke, and gastrointestinal bleeding with HM3 use relative to HMII use. Improvements in quality of life and functional capacity for either pump were not significantly different regardless of preimplant strategy. Conclusions and Relevance: In this trial, the superior treatment effect of HM3 over HMII was similar for patients in the BTT/BTC or DT groups. It is possible that use of arbitrary categorizations based on current or future transplant eligibility should be clinically abandoned in favor of a single preimplant strategy: to extend the survival and improve the quality of life of patients with medically refractory heart failure. Trial Registration: ClinicalTrials.gov identifier: NCT02224755.

Predictors of Cardiac Surgery Patients Who Tolerate Blood Conservation in Cardiac Surgery.

BACKGROUND: Whether there is a cardiac surgical patient population that does not incur harm from blood conservation is unknown. This study aimed to identify patient characteristics associated with patients who safely tolerate blood conservation. METHODS: We conducted a retrospective review of consecutive patients undergoing isolated coronary artery bypass graft surgery or isolated aortic valve replacement, or concomitant coronary artery bypass graft surgery and aortic valve replacement between 2011 and 2016, during which blood conservation intervention took place. Logistic regression derived from the preintervention cohort was applied to the postintervention cohort to identify patient characteristics associated with those predicted to be transfused in the preintervention era but were not in the postintervention era. RESULTS: In this series of 2,701 adult patients undergoing cardiac operations, blood conservation intervention in 2014 led to a 52% reduction in red blood cell transfusion. Between preintervention and postintervention cohorts, there was no significant difference in the measured outcomes. A regression model derived from the preintervention cohort was applied to the postintervention cohort to identify predictors of cohort that do not derive benefit from liberal transfusion. This model demonstrated such patient characteristics to be age more than 75 years (odds ratio [OR] 1.71, 95% confidence interval [CI]: 1.09 to 2.68, p = 0.033), body mass index less than 30 kg/m2 (OR 1.5, 95% CI: 1.02 to 2.20, p = 0.044), lowest intraoperative hematocrit between 22 and 25 (OR 1.77, 95% CI: 1.16 to 2.68, p < 0.001), and cardiopulmonary bypass use (OR 4.50, 95% CI: 2.25 to 9.01, p < 0.001). CONCLUSIONS: Blood conservation can successfully yield reduction in perioperative blood product use, with associated decrease in the risk of postoperative renal failure. A select patient population who may tolerate blood conservation safely was identified, and that may guide a targeted blood conservation effort.

Mathematical Blueprint of a Mitral Valve.

Mathematical modeling tries to simplify understanding and proposes a fundamental mechanism that governs the motion and function of a complex biological system such as a mitral valve (MV) motion which represents a dynamic interplay between papillary muscle (PM) position in the context of left ventricular (LV) shape dynamics. Current therapeutic strategies to intervene on the MV may not have exploited these relationships due to lack of understanding of the interactions. We present a MV 3D mathematical model characterized by LV shape dynamics to understand fundamental working principles of ventriculo-papillary-mitral complex. A complex 3D functional unit of MV apparatus was mathematically modeled based on a principle of dynamics. The model comprises of primary components including the annulus, anterior leaflet, posterior leaflet, chordae tendineae, anterior and posterior PM, and LV wall based on normal anatomical reference values from published series. Simulations based on Carpentier's classification of MV disease were created as well as based on LV shape dynamics and presented graphically. Autodesk Inventor (Autodesk Inc., San Rafael, CA) and Matlab (Mathworks, Natick, MA) were used for modeling and analysis. A stepwise analysis and mathematical models of the annulus, leaflets, chords, PMs, and LV were obtained by combining finite element analysis and computerized model creations. The model was then applied to Carpentier's functional classification. PM positions extrapolated based on different LV deformation in normal and mitral regurgitation (MR) model resulted in a different degree of MV leaflet coaptation with regurgitation (presented numerically and graphically). Abnormal MV coaptation was amended by manipulating PM positions independent with LV size or shape deformation, demonstrating that PM positioning maneuver may improve leaflet coaptation. LV dilation combined with increased interpapillary muscle distance turned out to intensify the level of leaflet prolapse, creating even greater regurgitation volume. Our mathematical model may provide a clue to complex interactions in play within a mitral, papillary, and LV complex. The model offers a possibility of manipulating various variables to obtain the desired outcome.

Improving Outcomes in INTERMACS Category 1 Patients with Pre-LVAD, Awake Venous-Arterial Extracorporeal Membrane Oxygenation Support.

Effective strategies to optimize Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS 1) patients are in much need. A novel awake venous-arterial extracorporeal membrane oxygenation (aVA ECMO) allows for clinical assessments while temporarily supporting biventricular function and stabilizing end-organ functions. The aim of the study was to assess outcomes of patients with aVA ECMO support before durable left ventricular assist device (LVAD) implantation. We evaluated 83 patients who received durable LVAD in 2012-2015, of whom 19 received aVA ECMO support before durable LVAD. Kaplan-Meier and Cox proportional hazards analyses were conducted to assess post-LVAD survival. No complications were observed during the mean aVA ECMO support of 2.7 days. Unadjusted survival of aVA ECMO-supported patients and non-aVA ECMO INTERMACS 1 patients at 1 year were 84.2% and 66.7%, respectively (p = 0.15). Survival of aVA ECMO patients was comparable with that of non-aVA ECMO INTERMACS 2 cohort (84.2% vs. 80.8%) at 1 year. Multivariate analysis demonstrated a significant reduction in the risk of death in aVA ECMO group compared with INTERMACS 1 non-aVA ECMO group (hazard ratio [HR]: 0.17; p = 0.035). Awake venous-arterial (VA) ECMO allows bridge to next therapy and improves outcomes in INTERMACS category 1 patients with an effect comparable with downgrading the disease severity on the INTERMACS scale.