Optimization of Absolute Coronary Blood Flow Measurements to Assess Microvascular Function: In Vivo Validation of Hyperemia and Higher Infusion Speeds

BACKGROUND

Reliable assessment of coronary microvascular function is essential. Techniques to measure absolute coronary blood flow are promising but need validation. The objectives of this study were: first, to validate the potential of saline infusion to generate maximum hyperemia in vivo. Second, to validate absolute coronary blood flow measured with continuous coronary thermodilution at high (40-50 mL/min) infusion speeds and asses its safety.

METHODS

Fourteen closed-chest sheep underwent absolute coronary blood flow measurements with increasing saline infusion speeds at different dosages under general anesthesia. An additional 7 open-chest sheep underwent these measurements with epicardial Doppler flow probes. Coronary flows were compared with reactive hyperemia after 45 s of coronary occlusion.

RESULTS

Twenty milliliters per minute of saline infusion induced a significantly lower hyperemic coronary flow (140 versus 191 mL/min; P=0.0165), lower coronary flow reserve (1.82 versus 3.21; P≤0.0001), and higher coronary resistance (655 versus 422 woods units; P=0.0053) than coronary occlusion. On the other hand, 30 mL/min of saline infusion resulted in hyperemic coronary flow (196 versus 192 mL/min; P=0.8292), coronary flow reserve (2.77 versus 3.21; P=0.1107), and coronary resistance (415 versus 422 woods units; P=0.9181) that were not different from coronary occlusion. Hyperemic coronary flow was 40.7% with 5 mL/min, 40.8% with 10 mL/min, 73.1% with 20 mL/min, 102.3% with 30 mL/min, 99.0% with 40 mL/min, and 98.0% with 50 mL/min of saline infusion when compared with postocclusive hyperemic flow. There was a significant bias toward flow overestimation (Bland-Altman: bias±SD, -73.09±30.52; 95% limits of agreement, -132.9 to -13.27) with 40 to 50 mL/min of saline. Occasionally, ischemic changes resulted in ventricular fibrillation (9.5% with 50 mL/min) at higher infusion rates.

CONCLUSIONS

Continuous saline infusion of 30 mL/min but not 20 mL/min induced maximal hyperemia. Absolute coronary blood flow measured with saline infusion speeds of 40 to 50 mL/min was not accurate and not safe.

Remotely Triggered LAD Occlusion Using a Balloon Catheter in Spontaneously Breathing Mice

Acute myocardial infarction (AMI) is a prevalent and high-mortality cardiovascular condition. Despite advancements in revascularization strategies for AMI, it frequently leads to myocardial ischemia-reperfusion injury (IRI), amplifying cardiac damage. Murine models serve as vital tools for investigating both acute injury and chronic myocardial remodeling in vivo. This study presents a unique closed-chest technique for remotely inducing myocardial IRI in mice, enabling the investigation of the very early phase of occlusion and reperfusion using in-vivo imaging such as MRI or PET. The protocol utilizes a remote occlusion method, allowing precise control over ischemia initiation after chest closure. It reduces surgical trauma, enables spontaneous breathing, and enhances experimental consistency. What sets this technique apart is its potential for simultaneous noninvasive imaging, including ultrasound and magnetic resonance imaging (MRI), during occlusion and reperfusion events. It offers a unique opportunity to analyze tissue responses in almost real-time, providing critical insights into processes during ischemia and reperfusion. Extensive systematic testing of this innovative approach was conducted, measuring cardiac necrosis markers for infarction, assessing the area at risk using contrast-enhanced MRI, and staining infarcts at the scar maturation stage. Through these investigations, emphasis was placed on the value of the proposed tool in advancing research approaches to myocardial ischemia-reperfusion injury and accelerating the development of targeted interventions. Preliminary findings demonstrating the feasibility of combining the proposed innovative experimental protocol with noninvasive imaging techniques are presented herein. These initial results highlight the benefit of utilizing the purpose-built animal cradle to remotely induce myocardial ischemia while simultaneously conducting MRI scans.

An interventional sheep model of severe aortic valve stenosis hemodynamics for the evaluation of alterations in coronary physiology and microvascular function

We aimed to develop a large animal model of subcoronary aortic stenosis (AS) to study intracoronary and microcirculatory hemodynamics. A total of three surgical techniques inducing AS were evaluated in 12 sheep. Suturing the leaflets together around a dilator (n = 2) did not result in severe AS. Suturing of a pericardial patch with a variable opening just below the aortic valve (n = 5) created an AS which was poorly tolerated if the aortic valve area (AVA) was too small (0.38-1.02 cm2), but was feasible with an AVA of 1.2 cm2. However, standardization of aortic regurgitation (AR) with this technique is difficult. Therefore, we opted for implantation of an undersized AV-bioprosthesis with narrowing sutures on the leaflets (n = 5). Overall, five sheep survived the immediate postoperative period of which three had severe AS (one patch and two bioprostheses). The surviving sheep with severe AS developed left ventricular hypertrophy and signs of increased filling-pressures. Intracoronary assessment of physiological indices in these AS sheep pointed toward the development of functional microvascular dysfunction, with a significant increase in coronary resting flow and hyperemic coronary resistance, resulting in a significantly higher index of microvascular resistance (IMR) and lower myocardial resistance reserve (MRR). Microscopic analysis showed myocardial hypertrophy and signs of fibrosis without evidence of capillary rarefaction. In a large animal model of AS, microvascular changes are characterized by increased resting coronary flow and hyperemic coronary resistance resulting in increased IMR and decreased MRR. These physiological changes can influence the interpretation of regularly used coronary indices.NEW & NOTEWORTHY In an animal model of aortic valve stenosis (AS), coronary physiological changes are characterized by increased resting coronary flow and hyperemic coronary resistance. These changes can impact coronary indices frequently used to assess concomitant coronary artery disease (CAD). At this point, the best way to assess and treat CAD in AS remains unclear. Our data suggest that fractional flow reserve may underestimate CAD, and nonhyperemic pressure ratios may overestimate CAD severity before aortic valve replacement.

Erector spinae plane block for postoperative analgesia in robotically-assisted coronary artery bypass surgery: Results of a randomized placebo-controlled trial

STUDY OBJECTIVE

To investigate if an erector spinae plane (ESP) block decreases postoperative opioid consumption, pain and postoperative nausea and vomiting in patients undergoing robotically-assisted minimally invasive direct coronary artery bypass surgery (RAMIDCAB).

DESIGN

A single-center, double-blind, prospective, randomized, placebo-controlled trial.

SETTING

Postoperative period; operating room, post-anesthesia care unit (PACU) and hospital ward in a university hospital.

PATIENTS

Sixty-four patients undergoing RAMIDCAB surgery via left-sided mini-thoracotomy and enrolled in the institutional enhanced recovery after cardiac surgery program.

INTERVENTIONS

At the end of surgery, patients received an ESP catheter at vertebra T5 under ultrasound guidance and were randomized to the administration of either ropivacaine 0.5% (loading dose of 30 ml and three additional doses of 20 ml each, interspersed with a 6 h interval) or normal saline 0.9% (with an identical administration scheme). In addition, patients received multimodal analgesia including acetaminophen, dexamethasone and patient-controlled analgesia with morphine. Following the final ESP bolus and before catheter removal, the position of the catheter was re-evaluated by ultrasound. Patients, investigators and medical personnel were blinded for the group allocation during the entire trial.

MEASUREMENTS

Primary outcome was cumulative morphine consumption during the first 24 h after extubation. Secondary outcomes included location and severity of pain, presence/extent of sensory block, duration of postoperative ventilation and hospital length of stay. Safety outcomes comprised the incidence of adverse events.

MAIN RESULTS

Median (IQR) 24-h morphine consumption was not different between the intervention- and control-groups, 67 mg (35-84) versus 71 mg (52-90) (p = 0.25), respectively. Likewise, no differences were detected in secondary and safety endpoints.

CONCLUSIONS

Following RAMIDCAB surgery, adding an ESP block to a standard multimodal analgesia regimen did not reduce opioid consumption and pain scores.

Myocardial ischemia-reperfusion injury and the influence of inflammation

Acute myocardial infarction is caused by a sudden coronary artery occlusion and leads to ischemia in the corresponding myocardial territory which generally results in myocardial necrosis. Without restoration of coronary perfusion, myocardial scar formation will cause adverse remodelling of the myocardium and heart failure. Successful introduction of percutaneous coronary intervention and surgical coronary artery bypass grafting made it possible to achieve early revascularisation/reperfusion, hence limiting the ischemic zone of myocardium. However, reperfusion by itself paradoxically triggers an exacerbated and accelerated injury in the myocardium, called ischemia-reperfusion (I/R) injury. This mechanism is partially driven by inflammation through multiple interacting pathways. In this review we summarize the current insights in mechanisms of I/R injury and the influence of altered inflammation. Multiple pharmacological and interventional therapeutic strategies (ischemic conditioning) have proven to be beneficial during I/R in preclinical models but were notoriously unsuccessful upon clinical translation. In this review we focus on common mechanisms of I/R injury, altered inflammation and potential therapeutic strategies. We hypothesize that a dual approach may be of value because I/R injury patients are predestined with multiple comorbidities and systemic low-grade inflammation, which requires targeted intervention before other strategies can be fully effective.

Robotic-assisted MIDCAB procedure through a minithoracotomy: Step-by-step instructions

Minimally invasive cardiac surgery has evolved in recent years. Complex minimally invasive surgical techniques can further reduce the morbidity associated with surgical coronary bypass grafting. Robotic-assisted minimally invasive direct coronary artery bypass grafting is an effective and safe procedure in all risk groups. More experience with this procedure over the coming years should lead to the implementation of guidelines and the incorporation in heart-team decisions of schemes for individual patient care. We present a young male patient with familial hypercholesterolemia and chronic total occlusion of the left anterior descending artery (LAD) treated in January 2021 with a robotic-assisted minimally invasive direct coronary artery bypass graft through a minithoracotomy. The procedure was. The patient showed a fast recovery from the uncomplicated procedure and was discharged from the hospital after 3 days. We prepared this case report to facilitate training for this complex technical procedure. Robotic-assisted MIDCAB through a minithoracotomy is a technically demanding but safe minimally invasive alternative to coronary artery bypass grafting in patients with severe coronary lesions not suitable for percutaneous coronary intervention. In a hybrid coronary revascularization strategy, this technique minimizes surgical risk and optimizes long-term outcomes with high patency of surgical grafts.

Arteriovenous Fistulae in Chronic Kidney Disease and the Heart: Physiological, Histological, and Transcriptomic Characterization of a Novel Rat Model

Background Arteriovenous fistulae (AVFs) are the gold standard for vascular access in those requiring hemodialysis but may put an extra hemodynamic stress on the cardiovascular system. The complex interactions between the heart, kidney, and AVFs remain incompletely understood. Methods and Results We characterized a novel rat model of five-sixths partial nephrectomy (NX) and AVFs. NX induced increases in urea, creatinine, and hippuric acid. The addition of an AVF (AVF+NX) further increased urea and a number of uremic toxins such as trimethylamine N-oxide and led to increases in cardiac index, left and right ventricular volumes, and right ventricular mass. Plasma levels of uremic toxins correlated well with ventricular morphology and function. Heart transcriptomes identified altered expression of 8 genes following NX and 894 genes following AVF+NX, whereas 290 and 1431 genes were altered in the kidney transcriptomes, respectively. Gene ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed gene expression changes related to cell division and immune activation in both organs, suppression of ribosomes and transcriptional activity in the heart, and altered renin-angiotensin signaling as well as chronodisruption in the kidney. All except the latter were worsened in AVF+NX compared with NX. Conclusions Inflammation and organ dysfunction in chronic kidney disease are exacerbated following AVF creation. Furthermore, our study provides important information for the discovery of novel biomarkers and therapeutic targets in the management of cardiorenal syndrome.

TRPM4 inhibition by meclofenamate suppresses Ca2+-dependent triggered arrhythmias

AIMS

Cardiac arrhythmias are a major factor in the occurrence of morbidity and sudden death in patients with cardiovascular disease. Disturbances of Ca2+ homeostasis in the heart contribute to the initiation and maintenance of cardiac arrhythmias. Extrasystolic increases in intracellular Ca2+ lead to delayed afterdepolarizations and triggered activity, which can result in heart rhythm abnormalities. It is being suggested that the Ca2+-activated nonselective cation channel TRPM4 is involved in the aetiology of triggered activity, but the exact contribution and in vivo significance are still unclear.

METHODS AND RESULTS

In vitro electrophysiological and calcium imaging technique as well as in vivo intracardiac and telemetric electrocardiogram measurements in physiological and pathophysiological conditions were performed. In two distinct Ca2+-dependent proarrhythmic models, freely moving Trpm4-/- mice displayed a reduced burden of cardiac arrhythmias. Looking further into the specific contribution of TRPM4 to the cellular mechanism of arrhythmias, TRPM4 was found to contribute to a long-lasting Ca2+ overload-induced background current, thereby regulating cell excitability in Ca2+ overload conditions. To expand these results, a compound screening revealed meclofenamate as a potent antagonist of TRPM4. In line with the findings from Trpm4-/- mice, 10 µM meclofenamate inhibited the Ca2+ overload-induced background current in ventricular cardiomyocytes and 15 mg/kg meclofenamate suppressed catecholaminergic polymorphic ventricular tachycardia-associated arrhythmias in a TRPM4-dependent manner.

CONCLUSION

The presented data establish that TRPM4 represents a novel target in the prevention and treatment of Ca2+-dependent triggered arrhythmias.

Revascularization strategies in patients with multivessel coronary artery disease: a Bayesian network meta-analysis

Treatment modalities for multivessel disease have rapidly evolved, yet the preferred strategy remains controversial. This meta-analysis compared outcomes after on-pump (ONCAB), off-pump coronary artery bypass grafting (OPCAB), percutaneous coronary intervention (PCI) or hybrid coronary revascularization. A comprehensive search for observational studies and randomized controlled trials published by August 2020 was performed. A Bayesian network meta-analysis was conducted for early (<30 days) and late (>12 months) outcomes. A total of 119 studies were included (n = 700 458 patients). The main analysis was confined to 31 randomized controlled trials (n = 24 932 patients). PCI was associated with lower early mortality [odds ratio (OR) 0.50, 95% confidence interval (CI) 0.31-0.79] and stroke (OR 0.22, 95% CI 0.06-0.60) rates compared with ONCAB, whereas a reduced risk of early myocardial infarction was observed with OPCAB compared with ONCAB (OR 0.53, 95% CI 0.32-0.83). Late target vessel revascularization and major adverse cardiac and cerebrovascular events were both increased with PCI compared with ONCAB, OPCAB and hybrid coronary revascularization (by 127-203% and 59-64%, respectively), and late major adverse cardiac events were increased in PCI compared with ONCAB and OPCAB (by 64% and 59%). However, PCI was associated with a significantly lower risk of late stroke compared with ONCAB (OR 0.70, 95% CI 0.52-0.89). Sensitivity analyses (i) including observational studies and (ii) limiting to studies with recent cohorts confirmed the findings of the main analysis. Surgical approaches for revascularization remain superior to PCI in patients with multivessel disease. Hybrid coronary revascularization might be viable for some patients, although more evidence from randomized controlled trials is warranted.

Robotic Cardiac Surgery in Europe: Status 2020

Background

European surgeons were the first worldwide to use robotic techniques in cardiac surgery and major steps in procedure development were taken in Europe. After a hype in the early 2000s case numbers decreased but due to technological improvements renewed interest can be noted. We assessed the current activities and outcomes in robotically assisted cardiac surgery on the European continent.

Methods

Data were collected in an international anonymized registry of 26 European centers with a robotic cardiac surgery program.

Results

During a 4-year period (2016–2019), 2,563 procedures were carried out [30.0% female, 58.5 (15.4) years old, EuroSCORE II 1.56 (1.74)], including robotically assisted coronary bypass grafting (n = 1266, 49.4%), robotic mitral or tricuspid valve surgery (n = 945, 36.9%), isolated atrial septal defect closure (n = 225, 8.8%), left atrial myxoma resection (n = 54, 2.1%), and other procedures (n = 73, 2.8%). The number of procedures doubled during the study period (from n = 435 in 2016 to n = 923 in 2019). The mean cardiopulmonary bypass time in pump assisted cases was 148.6 (63.5) min and the myocardial ischemic time was 88.7 (46.1) min. Conversion to larger thoracic incisions was required in 56 cases (2.2%). Perioperative rates of revision for bleeding, stroke, and mortality were 56 (2.2%), 6 (0.2 %), and 27 (1.1%), respectively. Median postoperative hospital length of stay was 6.6 (6.6) days.

Conclusion

Robotic cardiac surgery case numbers in Europe are growing fast, including a large spectrum of procedures. Conversion rates are low and clinical outcomes are favorable, indicating safe conduct of these high-tech minimally invasive procedures.

Hybrid coronary revascularization versus percutaneous coronary intervention: A systematic review and meta-analysis

BACKGROUND

Hybrid coronary revascularization (HCR) is an emerging approach for multivessel coronary artery disease (MVD) which combines the excellent long-term outcomes of surgery with the early recovery and reduced short-term complications of percutaneous coronary intervention (PCI). Here, we evaluated the effectiveness of HCR compared to PCI in patients with MVD.

METHODS

A systematic database search in PubMed/MEDLINE, Embase, Scopus, and CENTRAL/CCTR was conducted by June 2021. Random-effects meta-analysis was performed, comparing major adverse cardiac and cerebrovascular events (MACCE) at 30 days and at latest follow-up between patients undergoing HCR versus PCI.

RESULTS

A total of 27,041 patients (HCR: 939 patients, PCI: 26,102 patients) were included from seven studies published between 2013 and 2021. At latest follow-up, HCR was associated with lower rates of myocardial infarction (OR 0.40, 95% CI 0.20-0.80, p = 0.010) and target vessel revascularization (OR 0.49, 95% CI 0.37-0.64, p < 0.001), while the difference for MACCE did not reach statistical significance (OR 0.46, 95% CI 0.20-1.05, p = 0.061). No differences were observed in terms of 30-day outcomes, nor rates of mortality or stroke at latest follow-up.

CONCLUSIONS

HCR might be a valid alternative to multivessel PCI, demonstrating a lower incidence of MI and TVR. Center experience, well-coordinated heart team discussions, and good patient selection likely remain essential to ensure optimal outcomes. Future comparative studies are required to define the optimal target population.

The role of antiaggregant agents and anticoagulants in the prevention of aortic valve endocarditis: A double-cohort retrospective study

Objective

Antiaggregants (Ag) could prevent infective endocarditis (IE) in preclinical studies. In this study we investigated whether Ag or anticoagulants (Ac) were also protective in humans.

Methods

In part I we determined the incidence of IE of bioprosthetic aortic valves (PVE) in 333 consecutive patients who underwent aortic valve replacement for noninfective aortic insufficiency between 2009 and 2019. In part II we retrospectively analyzed data of 137 patients who had developed IE of the native aortic valve (NVE) between 2007 and 2015. Multivariable Fine–Gray and logistic regression models were used to investigate associations between Ag and Ac therapy and IE.

Results

Sixteen of 333 (4.8%) aortic valve replacement recipients developed PVE after a median of 3.72 years. There was no association between Ag and PVE, whereas Ac was associated with a higher IE occurrence (no association for vitamin K antagonists but significant for fondaparinux or low molecular-weight heparins; hazard ratio, 4.61; 95% CI, 1.01-21.9). In contrast, among the 137 patients in part II, vitamin K antagonists (odds ratio [OR], 7.52; 95% CI, 2.51-22.6), double antiplatelet therapy (OR, 44.3; 95% CI, 4.83-407), novel oral Ac (OR, 4.17; 95% CI, 1.15-15.1), and fondaparinux or low molecular-weight heparins (OR, 9.87; 95% CI, 1.81-53.9), but not acetylsalicylic acid, were associated with NVE.

Conclusions

Ac were associated with IE in both cohorts, whereas Ag were not associated with PVE. This might reflect differences in the studied populations, with Ag and Ac being prescribed for conditions associated with long-term IE risk in the NVE cohort. Therefore, determining the potential protective effect of Ag and Ac will necessitate further well–controlled studies.

Safe implementation of robotic-assisted minimally invasive direct coronary artery bypass: application of learning curves and cumulative sum analysis

Background

Learning curves are inevitably encountered when first implementing an innovative and complex surgical technique. Nevertheless, a cluster of failures or complications should be detected early, but not deter learning, to ensure safe implementation. Here, we aimed to examine the presence and impact of learning curves on outcome after robotic-assisted minimally invasive direct coronary artery bypass (RA-MIDCAB).

Methods

A retrospective analysis of the first 300 RA-MIDCAB surgeries between July 2015 and December 2020 was performed. Learning curves were obtained via logarithmic regression for surgical time. Cumulative sum (CUSUM) analysis was performed for (I) major complications including MI, stroke, repeat revascularization, and mortality, and (II) other complications, including prolonged ventilation, pneumonia, pleura puncture, lung herniation, pericarditis, pleuritis, arrhythmia, wound complications, and delirium. Expected and unacceptable rates were set at 12% and 20%, respectively, for major complications, and at 40% and 60% for other complications, based on historical data in conventional coronary artery bypass grafting (CABG).

Results

Demographic characteristics did not differ between terciles, except for more smokers in the first tercile, and less hypercholesterolemia and more complex procedures in the third tercile. The mean surgical time for all operations was 258±81 minutes, ranging from 127 to 821 minutes. A learning curve was only observed in the first tercile. Subgroup analysis revealed that this learning curve was only observed for procedures consisting of single internal mammary artery (SIMA) with 1 or 2 distal anastomoses but not with bilateral internal mammary arteries (BIMA) or more than 2 distal anastomoses. CUSUM analysis showed that the cumulative rate of major and other complications never crossed the lines for unacceptable rates. Rather, the lower 95% confidence boundary was crossed after 50 cases, indicating improvement in safety.

Conclusions

These results suggest that integration of RA-MIDCAB in the surgical landscape can be safely achieved and complication rates can quickly be reduced below those expected in traditional CABG. Collective experience plays a key role in overcoming the learning curve when more complex procedures and cases are introduced.

Antithrombotic Treatment After Surgical and Transcatheter Heart Valve Repair and Replacement

New antithrombotic drugs have been developed, new valve types have been designed and minimally invasive transcatheter techniques have emerged, making the choice of antithrombotic therapy after surgical or transcatheter heart valve repair and replacement increasingly complex. Moreover, due to a lack of large randomized controlled trials many recommendations for antithrombotic therapy are based on expert opinion, reflected by divergent recommendations in current guidelines. Therefore, decision-making in clinical practice regarding antithrombotic therapy for prosthetic heart valves is difficult, potentially resulting in sub-optimal patient treatment. This article compares the 2017 ESC/EACTS and 2020 ACC/AHA guidelines on the management of valvular heart disease and summarizes the available evidence. Finally, we established a convenient consensus on antithrombotic therapy after valve interventions based on over 800 annual cases of surgical and transcatheter heart valve repair and replacement and a multidisciplinary team discussion between the department of cardiovascular diseases and cardiac surgery of the University Hospitals Leuven, Belgium.

Hemoglobin A1c and preoperative glycemia as a decision tool to help minimise sternal wound complications: a retrospective study in OPCAB patients

Background

Poor glycemic control has been associated with an increased risk of wound complications after various types of operations. However, it remains unclear how hemoglobin A1c (HbA1c) and preoperative glycemia can be used in clinical decision-making to prevent sternal wound complications (SWC) following off-pump coronary artery bypass grafting (OPCAB).

Methods

We conducted a retrospective study of 1774 consecutive patients who underwent OPCAB surgery between January 2010 and November 2016. A new four-grade classification for SWC was used. The associations of HbA1c and preoperative glycemia with incidence and grade of SWC were analysed using logistic regression analysis and proportional odds models, respectively.

Results

During a median follow-up of 326 days (interquartile range (IQR) 21–1261 days), SWC occurred in 133/1316 (10%) of non-diabetes and 82/458 (18%) of diabetes patients (p < 0.001). Higher HbA1c was significantly associated with a higher incidence of SWC (odds ratio, OR 1.24 per 1% increase, 95% confidence interval, CI 1.04;1.48, p = 0.016) as well as a higher grade of SWC (OR 1.25, 95% CI 1.06;1.48, p = 0.010). There was no association between glycemia and incidence (p = 0.539) nor grade (p = 0.607) of SWC. Significant modifiers of these effects were found: HbA1c was associated with SWC in diabetes patients younger than 70 years (OR 1.41, 95% CI 1.17;1.71, p < 0.001), whereas it was not in those older than 70 years. Glycemia was associated with SWC in patients who underwent non-urgent surgery (OR 2.48, 95% CI 1.26;4.88, p = 0.009), in diabetes patients who received skeletonised grafts (OR 4.83, 95% CI 1.28;18.17, p = 0.020), and in diabetes patients with a BMI < 30 (OR 2.19, 95% CI 1.01;4.76, p = 0.047), whereas it was not in the counterparts of these groups.

Conclusions

Under certain conditions, HbA1c and glycemia are associated SWC following OPCAB. These findings are helpful in planning the procedure with minimal risk of SWC.

Coronary revascularization in patients with HIV

With combined antiretroviral therapy, people living with HIV (PLWH) survive longer and are now more likely to die from cardiovascular diseases. PLWH presenting with a ST-segment elevation myocardial infarction are likely to have a high thrombus burden and are at high risk for in-hospital and long-term adverse events. An increasing number of PLWH are presenting with stable coronary artery disease related to atherosclerosis. Revascularization in these patients is associated with higher in-hospital and long-term major adverse cardiovascular events, including stent thrombosis and in-stent restenosis. However, data in this expanding population concerning optimal revascularization strategy are still lacking. In particular, data comparing percutaneous versus surgical revascularization in PLWH are needed. In this review we highlight the currently available data related to coronary revascularization in PLWH.

Cardiac Microvascular Endothelial Cells in Pressure Overload-Induced Heart Disease

BACKGROUND

Chronic pressure overload predisposes to heart failure, but the pathogenic role of microvascular endothelial cells (MiVEC) remains unknown. We characterized transcriptional, metabolic, and functional adaptation of cardiac MiVEC to pressure overload in mice and patients with aortic stenosis (AS).

METHODS

In Tie2-Gfp mice subjected to transverse aortic constriction or sham surgery, we performed RNA sequencing of isolated cardiac Gfp⁺-MiVEC and validated the signature in freshly isolated MiVEC from left ventricle outflow tract and right atrium of patients with AS. We next compared their angiogenic and metabolic profiles and finally correlated molecular and pathological signatures with clinical phenotypes of 42 patients with AS (50% women).

RESULTS

In mice, transverse aortic constriction induced progressive systolic dysfunction, fibrosis, and reduced microvascular density. After 10 weeks, 25 genes predominantly involved in matrix-regulation were >2-fold upregulated in isolated MiVEC. Increased transcript levels of Cartilage Intermediate Layer Protein (Cilp), Thrombospondin-4, Adamtsl-2, and Collagen1a1 were confirmed by quantitative reverse transcription polymerase chain reaction and recapitulated in left ventricle outflow tract-derived MiVEC of AS (P<0.05 versus right atrium-MiVEC). Fatty acid oxidation increased >2-fold in left ventricle outflow tract-MiVEC, proline content by 130% (median, IQR, 58%-474%; P=0.008) and procollagen secretion by 85% (mean [95% CI, 16%-154%]; P<0.05 versus right atrium-MiVEC for all). The altered transcriptome in left ventricle outflow tract-MiVEC was associated with impaired 2-dimensional-vascular network formation and 3-dimensional-spheroid sprouting (P<0.05 versus right atrium-MiVEC), profibrotic ultrastructural changes, and impaired diastolic left ventricle function, capillary density and functional status, especially in female AS.

CONCLUSIONS

Pressure overload induces major transcriptional and metabolic adaptations in cardiac MiVEC resulting in excess interstitial fibrosis and impaired angiogenesis. Molecular rewiring of MiVEC is worse in women, compromises functional status, and identifies novel targets for intervention.

Implementation of a beating heart system for training in off-pump and minimally invasive coronary artery bypass

Background

Several training devices have been developed to train anastomotic skills in off-pump coronary artery bypass grafting (OPCAB). However, assessment of trainees’ improvement remains challenging. The goal of this study was to develop a new practical scoring chart and investigate its reliability and utility for anastomotic skills in OPCAB and minimally invasive direct coronary artery bypass (MIDCAB).

Methods

A training device was used, which included a beating heart model installed in a dedicated box. A soft plastic tube was used as the left anterior descending artery, and a porcine ureter was used as the left internal mammary artery. Five cardiac surgery fellows (Fellows, > 5 year of surgical experience) and five residents or medical students (Residents, ≤ 5 year of surgical experience) were enrolled for this study. Before and after training, skills were evaluated using a scoring chart that took into account anastomotic time, leakage, shape, flow measurement, and self-estimation.

Results

Mean total score of all trainees was 15.4 ± 4.0 at pre-training and 18.5 ± 2.4 at post-training (P = 0.05). Before training, there was a significant difference in the total score between Fellows and Residents (18.6 ± 2.2 vs 12.2 ± 2.4 points, P = 0.002), which disappeared after training (19.4 ± 2.5 vs 17.6 ± 2.2 points, P = 0.262). Residents benefitted from training with improvements in their time, total score, score for time, score for flow and subtraction score; however, these effects were not seen in Fellows. The most evident training effect was improvement of self-estimation, which was also seen in Fellows.

Conclusions

Residents were most likely to derive benefit from these training models with regard to both efficiency and quality. Training models seem to have an important role in making surgeons feel more comfortable with the procedure.

Heart team 2.0: A decision tree for minimally invasive and hybrid myocardial revascularization

Recent years have seen an important shift in the target population for myocardial revascularization. Patients are increasingly presenting with more complex coronary artery disease (CAD), but also with multiple comorbidities and frailty. At the same time, minimally invasive strategies such as Minimally Invasive Direct Coronary Artery Bypass Grafting (MIDCAB) and Percutaneous Coronary Interventions (PCI) have been developed, which might be more appealing for this group of patients. As a result, the landscape of options for myocardial revascularization is evolving while adequate use of all resources is required to ensure optimal patient care. Heart Teams are confronted with the challenge of incorporating the new minimally invasive strategies into the decision process, yet current guidelines do not fully address this challenge. In this review, the current evidence regarding outcomes, indications, benefits, and risks of off-pump coronary artery bypass grafting (OPCAB), MIDCAB, PCI, and hybrid coronary revascularization (HCR) are discussed. Based on this evidence and on experiences from Heart Team discussions, a new decision tree is proposed that incorporates recent advances in minimally invasive revascularization strategies, thereby optimizing adequate delivery of care for each individual patient's needs. Introducing all important considerations in a logical way, this tool facilitates the decision-making process and might ensure appropriate use of resources and optimal care for individual patients.

Cardiothoracic robotic assisted surgery in times of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic poses an immense threat to healthcare systems worldwide. At a time when elective surgeries are being suspended and questions are being raised about how the remaining procedures on COVID-19 positive patients can be performed safely, it is important to consider the potential role of robotic assisted surgery within the current pandemic. Recently, several robotic assisted surgery societies have issued their recommendations. To date, however, no specific recommendations are available for cardiothoracic robotic assisted surgery in COVID-19 positive patients. Here, we discuss the potential risks, benefits, and preventive measures that need to be taken into account when considering robotic assisted surgery for cardiothoracic indications in patients with confirmed COVID-19. It is suggested that robotic assisted surgery might have various advantages such as early recovery after surgery, shorter hospital stay, and reduced loss of blood and fluids as well as smaller incisions. However, electrosurgical and ultrasonic devices, as well as CO2 insufflation should be managed with caution to prevent the risk of aerosolization of viral particles.

Skeletonisation contributing to a reduction of sternal wound complications: a retrospective study in OPCAB patients

Background

Sternal wound complications (SWC) are a rare but potentially life-threatening complication after coronary artery bypass grafting (CABG) surgery. Especially the use of bilateral IMA (BIMA) grafts as opposed to single IMA (SIMA) grafts is associated with an increased risk of SWC. Skeletonised harvesting has been proposed to reduce this risk. The purpose of this study was to retrospectively investigate the effect of skeletonisation on SWC after off-pump coronary artery bypass grafting (OPCAB) in a centre with a high volume of off-pump procedures and high frequencies of BIMA.

Methods

From January 2010 to November 2016, 1900 consecutive patients underwent OPCAB surgery at the University Hospitals of Leuven. The first group (n = 1487) received non-skeletonised IMA grafts, whereas the second group (n = 413) received skeletonised grafts. Optimal wound management was pursued in all patients. A new four-grade classification for SWC was developed. Incidence and grade of SWC as well as overall survival were assessed.

Results

Analysis of diabetic patients showed a lower incidence of SWC in the skeletonised (12/141, 8.5%) compared to the non-skeletonised group (82/414, 19.8%) [odds ratio 0.46, 95% confidence interval (0.23;0.88), p = 0.019] as well as a lower grade [0.45 (0.24;0.871), p = 0.018]. There was no significant effect on overall survival [0.67 (0.19;2.32), p = 0.529]. Subanalysis of this population revealed that the observed effects were most prominent in patients receiving BIMA grafts, with 6/56 (10.7%) SWC in the skeletonised and 62/252 (24.6%) in the non-skeletonised group [0.37 (0.15;0.90), p = 0.028 for incidence], as well as a lower grade [0.36 (0.15;0.88), p = 0.025]. These advantages were not significant in diabetic patients receiving SIMA grafts nor in the full study population.

Conclusions

This study, using a more sensitive classification of SWC, shows in a large group of patients that, in combination with optimized wound management, the skeletonisation technique is associated with a clear reduction in the incidence and grade of SWC in diabetic patients receiving BIMA grafts. This encourages the extension of BIMA use in OPCAB to this risk population.

Electronic supplementary material

The online version of this article (10.1186/s13019-019-0985-9) contains supplementary material, which is available to authorized users.

Abstract 506: Trpm4 Contributes to Ca 2+ -dependent Triggered Arrhythmias in Pathological Conditions

Rationale: TRPM4 is a Ca 2+ -activated non-selective cation channel that is abundantly expressed in the heart. Mutations in the Trpm4 gene are associated with human cardiac conduction disorders, including Progressive Familial Heart Block type I (PFHBI) and Brugada Syndrome. However, the mechanistic role and in vivo significance of TRPM4 in the triggering of cardiac arrhythmias is still completely unclear.

Objective: To investigate the role of TRPM4 during pathological Ca 2+ handling in the heart.

Methods and results: Using three in vivo pro-arrhythmic assays, we found that Trpm4 -/- mice show a reduced arrhythmic burden compared to control mice. First, aconitine intoxication resulted in severe cardiac arrhythmias, both in WT and Trpm4 -/- animals, but Trpm4 -/- mice developed significantly less ventricular ectopic beats (VEBs) and showed a lower arrhythmic score. Second, during ischemia-reperfusion, induced by 30 min of LAD ligation, significantly more WT animals developed arrhythmias compared to Trpm4 -/- mice. Third, catecholaminergic polymorphic ventricular tachycardia (CPVT) mice, carrying mutations in RyR2, were subjected to a stress test. Significantly more RyR +/R2474S -Trpm4 +/+ animals developed arrhythmias compared to RyR +/R2474S -Trpm4 -/- mice.

Conclusion: Our data establish that TRPM4 represents a novel target in the prevention and treatment of cardiac arrhythmias.

Urethroplasty for urethral injuries and trauma-related strictures in children and adolescents: a single-institution experience

INTRODUCTION

Urethral injuries and trauma-related strictures (UITSs) in children are rare. The treatment is challenging but crucial to avoid life-long urinary complications such as recurrent stricture formation, urinary incontinence, and impotence.

OBJECTIVE

The aim was to report on the surgical and functional outcome of urethroplasty for UITSs and to provide data on patient-reported outcome measures (PROMs).

MATERIAL AND METHODS

Between November 2001 and October 2017, 18 male children (≤18 years; median: 13 years) underwent urethroplasty for UITSs at a single tertiary referral center. Etiology was iatrogenic in five (27.8%), perineal straddle injury in six (33.3%) and pelvic fracture urethral injury (PFUI) in seven (38.8%) patients. PFUIs and short (≤3 cm) bulbar strictures were treated by transperineal anastomotic repair (n = 15; 83.3%), whereas a long bulbar stricture and a penile stricture were treated by, respectively, a preputial skin graft and flap urethroplasty. A penetrating penile urethral injury during circumcision underwent early exploration with primary repair of the laceration. Failure was defined as need for additional urethral instrumentation. PROMs were sent to patients ≥16 years at the latest evaluation.

RESULTS

Median follow-up was 57 (range: 8-198) months. No complications and grade 1, 2, and 3 were present in, respectively, 13 (72.2%), two (11.1%), one (5.6%), and two (11.1%) patients. The success rate in a tertiary referral center was 94.4%. An immediate failure was observed in a patient with a PFUI and concomitant bladder neck injury. PROMs were available in 12 patients. Four patients (33.3%) reported erectile dysfunction. Post-void dribbling (25%) and urgency (50%) were the most frequently reported complaints. All patients were satisfied after urethroplasty and stated that they would undergo the surgery again.

DISCUSSION

This series corroborates the recent trend in favor of transperineal anastomotic repair for PFUI, with combined abdominoperineal approach reserved for complex situations (e.g. bladder neck injury). For anterior UITSs, adaption of the technique to the characteristics of UITSs (etiology, location, length, and quality of graft bed) yielded excellent outcomes. Future systematic use of PROMs is also needed in children to elucidate the impact of urethroplasty on the urinary and sexual function.

CONCLUSION

External trauma is the most important etiology of UITSs, but iatrogenic causes should not be neglected. Urethroplasty, mainly by anastomotic repair (AR) but with the technique adapted to local stricture characteristics if necessary, has an excellent long-term success rate in experienced hands. Functional disturbances are frequent, but despite this, patient satisfaction is high after urethroplasty.

Assessment of Physical Activity by Wearable Technology During Rehabilitation After Cardiac Surgery: Explorative Prospective Monocentric Observational Cohort Study

Background

Wearable technology is finding its way into clinical practice. Physical activity describes patients’ functional status after cardiac surgery and can be monitored remotely by using dedicated trackers.

Objective

The aim of this study was to compare the progress of physical activity in cardiac rehabilitation by using wearable fitness trackers in patients undergoing coronary artery bypass surgery by either the conventional off-pump coronary artery bypass (OPCAB) or the robotically assisted minimally invasive coronary artery bypass (RA-MIDCAB). We hypothesized faster recovery of physical activity after RA-MIDCAB in the first weeks after discharge as compared to OPCAB.

Methods

Patients undergoing RA-MIDCAB or OPCAB were included in the study. Each patient received a Fitbit Charge HR (Fitbit Inc, San Francisco, CA) physical activity tracker following discharge. Rehabilitation progress was assessed by measuring the number of steps and physical activity level daily. The physical activity level was calculated as energy expenditure divided by the basic metabolic rate.

Results

A total of 10 RA-MIDCAB patients with a median age of 68 (min, 55; max, 83) years and 12 OPCAB patients with a median age of 69 (min, 50; max, 82) years were included. Baseline characteristics were comparable except for body mass index (RA-MIDCAB: 26 kg/m²; min, 22; max, 28 versus OPCAB: 29 kg/m²; min, 27; max, 33; P<.001). Intubation time (P<.05) was significantly lower in the RA-MIDCAB group. A clear trend, although not statistically significant, was observed towards a higher number of steps in RA-MIDCAB patients in the first week following discharge.

Conclusions

RA-MIDCAB patients have an advantage in recovery in the first weeks of revalidation, which is reflected by the number of steps and physical activity level measured by the Fitbit Charge HR, as compared to OPCAB patients. However, unsupervised assessment of daily physical activity varied widely and could have consequences with regard to the use of these trackers as research tools.

ACE-inhibition induces a cardioprotective transcriptional response in the metabolic syndrome heart

Cardiovascular disease associated with metabolic syndrome has a high prevalence, but the mechanistic basis of metabolic cardiomyopathy remains poorly understood. We characterised the cardiac transcriptome in a murine metabolic syndrome (MetS) model (LDLR−/−; ob/ob, DKO) relative to the healthy, control heart (C57BL/6, WT) and the transcriptional changes induced by ACE-inhibition in those hearts. RNA-Seq, differential gene expression and transcription factor analysis identified 288 genes differentially expressed between DKO and WT hearts implicating 72 pathways. Hallmarks of metabolic cardiomyopathy were increased activity in integrin-linked kinase signalling, Rho signalling, dendritic cell maturation, production of nitric oxide and reactive oxygen species in macrophages, atherosclerosis, LXR-RXR signalling, cardiac hypertrophy, and acute phase response pathways. ACE-inhibition had a limited effect on gene expression in WT (55 genes, 23 pathways), and a prominent effect in DKO hearts (1143 genes, 104 pathways). In DKO hearts, ACE-I appears to counteract some of the MetS-specific pathways, while also activating cardioprotective mechanisms. We conclude that MetS and control murine hearts have unique transcriptional profiles and exhibit a partially specific transcriptional response to ACE-inhibition.

The human somatostatin receptor type 2 as an imaging and suicide reporter gene for pluripotent stem cell-derived therapy of myocardial infarction

Rationale: Pluripotent stem cells (PSCs) are being investigated as a cell source for regenerative medicine since they provide an infinitive pool of cells that are able to differentiate towards every cell type of the body. One possible therapeutic application involves the use of these cells to treat myocardial infarction (MI), a condition where billions of cardiomyocytes (CMs) are lost. Although several protocols have been developed to differentiate PSCs towards CMs, none of these provide a completely pure population, thereby still posing a risk for neoplastic teratoma formation. Therefore, we developed a strategy to (i) monitor cell behavior noninvasively via site-specific integration of firefly luciferase (Fluc) and the human positron emission tomography (PET) imaging reporter genes, sodium iodide symporter (hNIS) and somatostatin receptor type 2 (hSSTr2), and (ii) perform hSSTr2-mediated suicide gene therapy via the clinically used radiopharmacon ¹⁷⁷Lu-DOTATATE.

Methods: Human embryonic stem cells (ESCs) were gene-edited via zinc finger nucleases to express Fluc and either hNIS or hSSTr2 in the safe harbor locus, adeno-associated virus integration site 1. Firstly, these cells were exposed to 4.8 MBq ¹⁷⁷Lu-DOTATATE in vitro and cell survival was monitored via bioluminescence imaging (BLI). Afterwards, hNIS⁺ and hSSTr2⁺ ESCs were transplanted subcutaneously and teratomas were allowed to form. At day 59, baseline ¹²⁴I and ⁶⁸Ga-DOTATATE PET and BLI scans were performed. The day after, animals received either saline or 55 MBq ¹⁷⁷Lu-DOTATATE. Weekly BLI scans were performed, accompanied by ¹²⁴I and ⁶⁸Ga-DOTATATE PET scans at days 87 and 88, respectively. Finally, hSSTr2⁺ ESCs were differentiated towards CMs and transplanted intramyocardially in the border zone of an infarct that was induced by left anterior descending coronary artery ligation. After transplantation, the animals were monitored via BLI and PET, while global cardiac function was evaluated using cardiac magnetic resonance imaging.

Results: Teratoma growth of both hNIS⁺ and hSSTr2⁺ ESCs could be followed noninvasively over time by both PET and BLI. After ¹⁷⁷Lu-DOTATATE administration, successful cell killing of the hSSTr2⁺ ESCs was achieved both in vitro and in vivo, indicated by reductions in total tracer lesion uptake, BLI signal and teratoma volume. As undifferentiated hSSTr2⁺ ESCs are not therapeutically relevant, they were differentiated towards CMs and injected in immune-deficient mice with a MI. Long-term cell survival could be monitored without uncontrolled cell proliferation. However, no improvement in the left ventricular ejection fraction was observed.

Conclusion: We developed isogenic hSSTr2-expressing ESCs that allow noninvasive cell monitoring in the context of PSC-derived regenerative therapy. Furthermore, we are the first to use the hSSTr2 not only as an imaging reporter gene, but also as a suicide mechanism for radionuclide therapy in the setting of PSC-derived cell treatment.

In vivo evidence for long-term vascular remodeling resulting from chronic cerebral hypoperfusion in mice

We have characterized both acute and long-term vascular and metabolic effects of unilateral common carotid artery occlusion in mice by in vivo magnetic resonance imaging and positron emission tomography. This common carotid artery occlusion model induces chronic cerebral hypoperfusion and is therefore relevant to both preclinical stroke studies, where it serves as a control condition for a commonly used mouse model of ischemic stroke, and neurodegeneration, as chronic hypoperfusion is causative to cognitive decline. By using perfusion magnetic resonance imaging, we demonstrate that under isoflurane anesthesia, cerebral perfusion levels recover gradually over one month. This recovery is paralleled by an increase in lumen diameter and altered tortuosity of the contralateral internal carotid artery at one year post-ligation as derived from magnetic resonance angiography data. Under urethane/α-chloralose anesthesia, no acute perfusion differences are observed, but the vascular response capacity to hypercapnia is found to be compromised. These hemispheric perfusion alterations are confirmed by water [¹⁵O]-H₂O positron emission tomography. Glucose metabolism ([¹⁸F]-FDG positron emission tomography) or white matter organization (diffusion-weighted magnetic resonance imaging) did not show any significant alterations. In conclusion, permanent unilateral common carotid artery occlusion results in acute and long-term vascular remodeling, which may have immediate consequences for animal models of stroke but also vascular dementia.

Routine thymectomy in congenital cardiac surgery changes adaptive immunity without clinical relevance

The actual importance of the thymus in both children and adults is largely unclear. In congenital cardiac surgery, a partial or total thymectomy is frequently performed to improve access to the heart and great vessels. We performed a literature search to evaluate the effect on the adaptive immune system of the removal of thymus tissue in patients with congenital heart disease. A PubMed search according to Dunning's standard provided 149 articles, of which 13 addressed our search question. Each study has been tabulated with author, cases, controls, follow-up, methods, results and limitations. A first group of articles repeatedly showed the effect on the T-cell compartment, including the impact on subgroups of this compartment. More recent studies, usually with a longer follow-up, confirm that the earlier changes in T-cell population appear to be permanent. Only one author found a normalization of T-cell population five years after thymectomy. In contrast to these clear changes in T-cell population, there is currently no clear clinical relevance. A literature search on thymectomy in congenital cardiac surgery revealed clear changes in T-cell-related immunity; however, there is a lack of clinical relevance. Further investigation of the adaptive immune system is required to explain this discrepancy.

Revision of perineal urethrostomy using a meshed split-thickness skin graft

Perineal urethrostomy is considered to be the last option to restore voiding in complex/recurrent urethral stricture disease. It is also a necessary procedure after penectomy or urethrectomy. Stenosis of the perineal urethrostomy has been reported in up to 30% of cases. There is no consensus on how to treat a stenotic perineal urethrostomy, but, in general, a form of urinary diversion is offered to the patient. We present the case of a young male who underwent perineal urethrostomy after urethrectomy for urethral cancer. The postoperative period was complicated by wound dehiscence with subsequent complete obliteration of the perineal urethrostomy. Revision surgery was performed with reopening of the obliterated urethral stump and coverage of the skin defect between the urethra and the perineal/scrotal skin with a meshed split-thickness skin graft. To date, this patient is voiding well and satisfied with the offered solution.

2-D strain assessment in the mouse through spatial compounding of myocardial velocity data: in vivo feasibility

Ultrasound assessment of myocardial strain can provide valuable information on regional cardiac function. However, Doppler-based methods often used in practice for strain estimation suffer from angle dependency. In this study, a partial solution to that fundamental limitation is presented. We have previously reported using simulated data sets that spatial compounding of axial velocities obtained at three steering angles can theoretically outperform 2-D speckle tracking for 2-D strain estimation in the mouse heart. In this study, the feasibility of the method was analyzed in vivo using spatial compounding of Doppler velocities on six mice with myocardial infarction and five controls, and results were compared with those of tagged microscopic magnetic resonance imaging (μMRI). Circumferential estimates quantified by means of both ultrasound and μMRI could detect regional dysfunction. Between echocardiography and μMRI, a good regression coefficient was obtained for circumferential strain estimates (r = 0.69), whereas radial strain estimates correlated only moderately (r = 0.37). A second echocardiography was performed after μMRI to test the reproducibility of the compounding method. This yielded a higher correlation coefficient for the circumferential component than for the radial component (r = 0.74 circumferentially, r = 0.49 radially).