Perioperative care in infective endocarditis.

Patients undergoing surgery for acute infective endocarditis are among those with the highest risk. Their preoperative condition has significant impact on outcomes. There are specific issues related with the preoperative situation, intraoperative findings, and postoperative management. In this narrative review, focus is placed on the most critical aspects in the perioperative period including the management and weaning from mechanical ventilation, the management of vasoplegia, the management of the chest open, antithrombotic therapy, transfusion, coagulopathy, management of atrial fibrillation, the duration of antibiotic therapy, and pacemaker implantation.

Significance and current approaches to vascular graft infection.

Vascular graft/endograft infection (VGEI) is a constant in cardiovascular surgery with published rates between 1 and 5%. Every graft type and anatomical location is a potential target for infectious complications. These patients are sick patients with high frailty burden. Management of VGEI entails a multidisciplinary and multimodality approach. Here we review some aspects of the problem of VGEI including prevention, diagnosis, and surgical therapy with focus on recent developments in the field.

Monomeric glutaraldehyde fixation and amino acid detoxification of decellularized bovine pericardium for production of biocompatible tissue with tissue-guided regenerative potential.

The effect of monomeric glutaraldehyde fixation and amino acid detoxification on biocompatibility and tissue-guided regenerative potential of decellularized bovine pericardium was evaluated. The degree of cross-linking, porosity, enzymatic degradation, alpha-galactosyl content, the efficacy of detoxification, and cytotoxicity towards human epithelial cells were assessed. Tissue was subcutaneously implanted for eight weeks in male juvenile Sprague-Dawley rats, and mechanical properties, host cell infiltration, and calcification were evaluated. Three groups were compared i) decellularized tissue, ii) decellularized, monomeric glutaraldehyde fixed and amino acid detoxified tissue, and iii) commercial glutaraldehyde fixed non-decellularized tissue (Glycar®) (n = 6 rats per group). The fixation process gave a high degree of cross-linking (>85%), and was resistant to enzymatic degradation, with no significant effect on porosity. The detoxification process was effective, and the tissue was not toxic to mammalian cells in vitro. Tissue from both decellularized groups had significantly higher (p < 0.05) porosity and host cell infiltration in vivo. The process mitigated calcification. A non-significant decrease in the alpha-galactosyl content was observed, which increased when including the alpha-galactosidase enzyme. Mechanical properties were maintained. The fixation and detoxification process adequately removes free aldehyde groups and reduces toxicity, preventing enzymatic degradation and allowing for host cell infiltration while mitigating calcification and retaining the mechanical properties of the tissue. This process can be considered for processing decellularized bovine pericardium with tissue-guided regeneration potential for use in cardiovascular bioprostheses; however, methods of further reducing antigenicity, such as the use of enzymes, should be investigated.

Outcomes of neonatal critical congenital heart disease: results of a prospective registry-based study from South India.

OBJECTIVES: Congenital heart disease (CHD) is now a leading contributor of infant and neonatal mortality in many low/middle-income countries including India. We established a prospective neonatal heart disease registry in Kerala to understand presentation of CHD, proportion of newborns with critical defects who receive timely intervention, outcomes at 1 month, predictors of mortality and barriers to timely management. METHODS: The congenital heart disease registry for newborns (≤28 days) in Kerala (CHRONIK) was a prospective hospital-based registry involving 47 hospitals from 1 June 2018 to 31 May 2019. All CHDs, except small shunts with a high likelihood of spontaneous closure, were included. Data on demographics, complete diagnosis, details of antenatal and postnatal screening, mode of transport and distance travelled and need for surgical or percutaneous interventions and survival were collected. RESULTS: Of the 1474 neonates with CHD identified, 418 (27%) had critical CHD, 22% of whom died at 1 month. Median age at diagnosis of critical CHD was 1 (0-22) day. Pulse oximeter screening identified 72% of critical CHD and 14% were diagnosed prenatally. Only 8% of neonates with duct-dependent lesions were transported on prostaglandin. Preoperative mortality accounted for 86% all deaths. On multivariable analysis, only birth weight (OR 2.7; 95% CI 2.1 to 6.5; p<0.0005) and duct-dependent systemic circulation (OR 6.43; 95% CI 5 to 21.8, p<0.0005) were predictive of mortality. CONCLUSIONS: While systematic screening, especially pulse oximetry screening, enabled early identification and prompt management of a significant proportion of neonates with critical CHD, important health system challenges like low use of prostaglandin need to be overcome to minimise preoperative mortality.

Comparison of the function and structural integrity of cryopreserved pulmonary homografts versus decellularized pulmonary homografts after 180 days implantation in the juvenile ovine model.

Homograft availability and durability remain big challenges. Increasing the post-mortem ischaemic harvesting time beyond 24 h increases the potential donor pool. Cryopreservation, routinely used to preserve homografts, damages the extracellular matrix (ECM), contributing to valve degeneration. Decellularization might preserve the ECM, promoting host-cell infiltration and contributing towards better clinical outcomes. This study compared the performance of cryopreserved versus decellularized pulmonary homografts in the right ventricle outflow tract (RVOT) of a juvenile ovine model. Homografts (n = 10) were harvested from juvenile sheep, subjected to 48 h post-mortem cold ischaemia, cryopreserved or decellularized and implanted in the RVOT of juvenile sheep for 180 days. Valve performance was monitored echocardiographically. Explanted leaflet and wall tissue evaluated histologically, on electron microscopical appearance, mechanical properties and calcium content. In both groups the annulus diameter increased. Cryopreserved homografts developed significant (¾) pulmonary regurgitation, with trivial regurgitation (») in the decellularized group. Macroscopically, explanted cryopreserved valve leaflets retracted and thickened while decellularized leaflets remained thin and pliable with good coaptation. Cryopreserved leaflets and walls demonstrated loss of interstitial cells with collapsed collagen, and decellularized scaffolds extensive, uniform ingrowth of host-cells with an intact collagen network. Calcific deposits were shown only in leaflets and walls of cryopreserved explants. Young fibroblasts, with vacuoles and rough endoplasmic reticulum in the cytoplasm, repopulated the leaflets and walls of decellularized scaffolds. Young's modulus of wall tissue in both groups increased significantly. Cryopreserved valves deteriorate over time due to loss of cellularity and calcification, while decellularized scaffolds demonstrated host-cell repopulation, structural maintenance, tissue remodelling and growth potential.

Early multicenter experience of a new balloon expandable MyVal transcatheter heart valve in dysfunctional stenosed right ventricular outflow tract conduits.

BACKGROUND: Transcatheter pulmonary valve implantation (TPVI) is a surgical alternative for correcting dysfunctional right ventricular outflow tract conduits in previously operated patients. MyVal transcatheter heart valve (THV) (Meril Life Sciences, India), a new transcatheter valve designed for aortic position has not been used for TPVI. METHODS: Patients with stenosed dysfunctional conduits from the right ventricle to pulmonary artery (RV-PA) were prestented after initial computed tomography and balloon interrogation before the implantation of MyVal. Size of MyVal was chosen based on the final diameter of the prestent. Procedural details and post-TPVI follow-up were analyzed. RESULTS: Seven patients aged 17-60 years (median 26 years) had stenosed RV-PA conduits implanted 5-17 years (median 9 years) ago for tetralogy of Fallot in three, following Ross procedure in two, repair of pulmonary stenosis, and following PA debanding in one patient each. Prestenting improved the conduit diameter from 9.3 ± 2.8 mm to 20.8 ± 1.1 mm and relieved the gradient from 87.3 ± 31.7 mmHg (50-137 mmHg) to 12.7 ± 6.4 mmHg (5-20 mmHg). A 23 mm MyVal was implanted in all the seven patients successfully; one patient needed an additional 24.5 mm MyVal valve in valve implantation for residual regurgitation. The mean fluoroscopic time and dose area product were 38.7 ± 25.3 min and 66.917 ± 39.211Gray. cm2, respectively. At a median follow-up duration of 16 months (10-22 months), all patients were asymptomatic receiving dual antiplatelet therapy with no PR and the gradient was 12.5 ± 5.8 mmHg on echocardiography. Although one patient needed an additional valve-in-valve implantation, there were no valve-related adverse events. CONCLUSIONS: Early experience of TPVI with MyVal THV in prestented conduits is encouraging with procedural success in all patients and acceptable mid-term outcomes.

Alternative mechanical heart valves for the developing world.

Due to the prevalence of rheumatic heart disease in the developing world, mechanical heart valves in the younger patient population remain the prostheses of choice if repair is not feasible. Despite their durability, mechanical valves are burdened by coagulation and thromboembolism. Modern design tools can be utilized during the design process of mechanical valves, which allow a more systematic design approach and more detailed analysis of the blood flow through and around valves. These tools include computer-aided design, manufacturing, and engineering, such as computational fluid dynamics and finite element analysis, modern manufacturing techniques such as additive manufacturing, and sophisticated in-vitro and in-vivo tests. Following this systematic approach, a poppet valve was redesigned and the results demonstrate the benefits of the method. More organized flow patterns and fewer complex fluid structures were observed. The alternative trileaflet valve design has also been identified as a potential solution and, if a similar design approach is adopted, it could lead to the development of an improved mechanical heart valve in the future. It is imperative that researchers in developing countries continue their search for a mechanical heart valve with a reduced thromboembolic risk, requiring less or no anticoagulation.

Explanting the migrated hepatic stent in the right atrium by modified vena caval inflow occlusion.

Stenting of hepatic veins can be a long lasting solution for Budd-Chiari syndrome. These stents could very rarely migrate into the right atrium. During surgical retrieval, cardiopulmonary bypass (CPB) can be avoided if vena caval inflow occlusion (VCIO) is used. A hybrid alternative of VCIO by using a balloon to occlude the inferior vena cava was done to retrieve the stent thus avoiding CPB and total circulatory arrest.

Cadaver donation: structural integrity of pulmonary homografts harvested 48 h post mortem in the juvenile ovine model.

Cryopreserved pulmonary homograft (CPH) implantation remains the gold standard for reconstruction of the right ventricular outflow tract (RVOT). Harvesting homografts < 24-h post mortem is the international norm, thereby largely excluding cadaveric donors. This study examines the structural integrity and stability of ovine pulmonary homografts harvested after a 48-h post mortem period, cryopreserved and then implanted for up to 180 days. Fifteen ovine pulmonary homografts were harvested 48-h post mortem and cryopreserved. Five CPH served as a control group (group 1; n = 5). CPH were implanted in the RVOT of juvenile sheep and explanted after 14 days (group 2; n = 5) and 180 days (group 3; n = 5). Leaflet integrity was evaluated by strength analysis, using tensile strength (TS), Young's modulus (YM) and thermal denaturation temperature (Td), and morphology, including haematoxylin and eosin (H&E), Picrosirius red staining, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and von Kossa stains. Echocardiography confirmed normal function in all implants. In explants, no reduction in TS, YM or Td could be demonstrated and H&E showed mostly acellular leaflet tissue with no difference on Picrosirius red. TEM demonstrated consistent collagen disruption after cryopreservation in all three groups, with no morphological deterioration during the study period. von Kossa stains showed mild calcification in group 3. No deterioration of structural integrity could be demonstrated using strength or morphological evaluations between the controls and implant groups over the study period. Extending the post mortem harvesting time of homografts beyond 24 h did not appear to negatively affect the long-term performance of such transplanted valves in this study.

Reprogramming Bone Marrow Stem Cells to Functional Endothelial Cells in a Mini Pig Animal Model.

BACKGROUND The aims of this study were to compare the morphological, biochemical, and functional properties of reprogrammed bone marrow stem cell (BMSC)-derived arterial endothelial cells (AECs) and venous endothelial cells (VECs), following adenosine triphosphate (ATP)-stimulation in a mini pig animal model. MATERIAL AND METHODS Bone marrow aspiration was performed in six adult mini pigs. Harvested mononuclear cells were isolated, cultured, and treated with vascular endothelial growth factor (VEGF) (16 µg/ml). Transformed cells were characterized using immunofluorescence staining for CD31 and von Willebrandt factor (vWF) and expression of endothelial nitric oxide synthase (eNOS). Cell release of nitric oxide (cNO) was measured using spectrophotometry. Matrigel assays were used to investigate angiogenesis in transformed BMSCs. RESULTS Reprogrammed BMSCs in culture showed a typical cobblestone-like pattern of growth. Immunofluorescence staining was positive for CD31 and vWF expression. Expression of eNOS, using immunofluorescence staining and Western blot, showed no difference between the reprogrammed BMSCs and VECs. Spectrophotometric examination following stimulation with 10mmol/l ATP, showed comparable cNO release for reprogrammed BMSCs (10.87±1.76 pmol/106 cells/min) and VECs (13.23±2.16 pmol/10^6 cells/min), but reduced cNO release for AECS (3.44±0.75 pmol/10^6 cells/min). Matrigel assay for angiogenesis showed vascular tube formation of differentiated BMSC endothelial cells (grade 3.25). BMSCs cultured without VEGF did not demonstrate vascular tube formation. CONCLUSIONS The findings of this study showed that eNOS expression and release of NO could be used to show that BMSCs can be reprogrammed to functional VECs and AECs.

Does prolonged post-mortem cold ischemic harvesting time influence cryopreserved pulmonary homograft tissue integrity?

This study investigated cryopreserved pulmonary homograft (CPA) structural integrity after prolonged cold ischemic harvesting times in a juvenile sheep model. Three groups with different post-mortem cold ischemic harvesting times were studied, i.e. Group 1 (24 h, n = 10); group 2 (48 h, n = 10); group 3 (72 h, n = 10). In each group, 5 CPAs were studied in vitro after cryopreservation and thawing. The other 5 CPAs were implanted in juvenile sheep for a minimum of 180 days. Serology samples were obtained and echocardiography was performed before euthanasia. Hematoxylin and eosin (H&E), scanning electron microscopy (SEM), von Kossa, Picrosirius red, α-actin, immunohistochemistry [von Willebrand factor (vWF), CD4, CD31 and CD34] and calcium content analyses were performed on explanted CPAs. The in vitro and in vivo studies failed to demonstrate any change in tensile strength, Young's Modulus and thermal denaturation (Td) results between the groups. SEM demonstrated a reduction in endothelial cells (50 % at 24 h, 60.9 % at 48 h and 40.9 % at 72 h), but H&E could not demonstrate autolysis in any CPA in vitro. All cultures were negative. In the explanted groups, IgE, IgM and IgG results were inconclusive. Echocardiography demonstrated normal valve function in all groups. H&E and Picrosirius red staining confirmed tissue integrity. vWF, CD31 and CD34 staining confirmed a monolayer of endothelial cells in all explanted valves. Calcium content of explanted CPA leaflets was similar. This experimental study supports the concept of prolonging the cold ischemic harvesting time of cryopreserved homografts to reduce homograft shortage.

Anomalous left coronary artery from nonfacing pulmonary sinus: direct aortic reimplantation.

We report a new technique of establishing a direct coronary transfer for anomalous left coronary artery arising from the nonfacing sinus of the pulmonary artery. This easily reproducible technique was successfully used in 2 patients. It achieves a dual coronary repair without the use of complex aortic or pulmonary arterial flaps and without causing any distortion to the great vessels.

Tricuspid valve mycetoma in an infant successfully treated by excision and complex tricuspid valve repair followed by fluconazole therapy.

BACKGROUND: Fungal valve endocarditis in children is an uncommon and lethal disease. The risk increases with use of central venous catheters (CVC), total parenteral nutrition (TPN), and use of broad-spectrum antibiotics during the neonatal period. Due to high mortality, a combination of surgery and antifungal therapy is usually recommended for treatment. METHODS: Case report and review of the literature. RESULTS: We present a case of an asymptomatic infant with multiple Candida tricuspid valve mycetomas. Complete cure was achieved by combined tricuspid valve repair and fluconazole therapy. We also review 26 cases of tricuspid valve Candida endocarditis in children published in the literature. CONCLUSION: From being uniformly fatal five decades ago to a current survival rate of 64% to 100%, the prognosis of Candida endocarditis has changed dramatically with the use of antifungal therapy alone or in combination with surgery. Our case re-emphasizes the role of valve-sparing debridement with repair of the native valve using autologous pericardium in combination with long-term antifungal therapy as a feasible option in managing tricuspid valve Candida endocarditis.

Two-ventricle repair for complex congenital heart defects palliated towards single-ventricle repair.

OBJECTIVES: Complex congenital heart defects that present earlier in life are sometimes channelled towards single-ventricle repair, because of anatomical or logistic challenges involved in two-ventricle correction. Given the long-term functional and survival advantage, we have been consciously exploring the feasibility of a biventricular repair in these patients when they present later for Fontan completion. METHODS: Since June 2009, 71 patients were referred for staged completion of the Fontan procedure. Following detailed evaluation that included three-dimensional echocardiography and magnetic resonance imaging, 10 patients (Group 1-median age 6 years) were identified and later underwent complex biventricular repair with takedown of Glenn shunt, while completion of extracardiac Fontan repair was done in 61 patients (Group 2-median age 7 years). RESULTS: Two-ventricle repair was accomplished in all the 10 Group 1 patients. One patient developed complete heart block requiring permanent pacemaker insertion. Late patch dehiscence occurred in another (awaiting repair). At a median follow-up of 15 months, there was no mortality among the Group 1 patients and all except for 1 patient were symptom free. There were 2 early deaths (3.3%) in the Group 2 patients. CONCLUSIONS: Two-ventricular repair, although surgically challenging, should be considered in all patients with two functional ventricles who come for Fontan completion. Comprehensive preoperative imaging and meticulous planning helps in identifying suitable candidates.

Palliative stenting of patent ductus arteriosus in older children and young adults with congenital cyanotic heart disease.

OBJECTIVE: To describe the indications, technique and results (early and short-term follow-up) of palliative patent ductus arteriosus (PDA) stenting in selected patients (2 years and older) with congenital cyanotic heart disease with reduced pulmonary blood flow who were not candidates for definitive surgery in the immediate future. BACKGROUND: Stenting of PDA as a palliation has been advocated as safe and effective procedure in neonates, but this modality is underutilized for children and adults. METHODS: Hospital records of patients (≥2 years) undergoing PDA stenting between January 2007 and September 2009 were reviewed. The access and approach was dictated by the anatomy of the PDA. A coronary guiding catheter or a long sheath was used to access the PDA. Coronary or peripheral stents were used for stenting. RESULTS: Fifteen patients with median age 14 years (range: 2-18 years); median weight 17.5 kg (range: 7-57 Kg) were included. Indication for intervention was hypoxia (mean saturation 69% ± 8.9%, hemoglobin 19.8 ± 2.69 g/dl), unsuitable anatomy or economic considerations. Successful stenting was accomplished in all (mean fluoroscopy time of 24.6 ± 16.7 min) with no complications and the saturations improved to mean of 88% ± 2.3 %. The most recent oxygen saturations on follow-up (median: 13 months; range: 1-21 months) were 82% ± 2.8%. One patient underwent corrective repair. CONCLUSION: PDA stenting can provide effective palliation in selected older patients with cyanotic congenital heart disease.

Off-pump atrial septostomy with thoracoscopic scissors under transesophageal echocardiography guidance.

Selected children with congenital heart defects undergoing palliative closed heart procedures require a cardiopulmonary bypass (CPB) run only for the purpose of creating an inter-atrial communication. We report a simple technique of atrial septostomy using thoracoscopy scissors under transesophageal echocardiography guidance without the need for CPB.

Cardiac allografts: a 24-year South African experience.

The history of using homologous cardiac valves dates back more than 30 years. Through the years emphasis was placed on the optimization of graft retrieval, preservation techniques and clinical application. A cardiac homograft valve bank was established at the Department of Cardiothoracic Surgery, University of the Free State, Bloemfontein in 1982. A retrospective analysis was performed on all allograft data since 1984. Since the first valve was successfully procured and transplanted in 1984, 2,540 aortic and pulmonary homografts were harvested from 1,792 donors, of which 1,545 [989 (64%) aortic and 556 (36%) pulmonary] were released for clinical use. Valves were discarded for various reasons, the main reasons being Human Immunodeficiency Virus (32.4%), Hepatitis B (9.6%) and venereal diseases (8.9%). The mean donor age was 26.98 years with a male predominance of 1,368 males versus 424 females. The average ischemic time was 33 h mainly due to medico-legal autopsies exceeding the desired 24 h time limit. The valves were disinfected in an antibiotic cocktail of Mefoxin, Piperacillin, Amikacin and Amphotericin B prior to cryopreservation. The surgical procedures utilizing the majority of homografts were aortic valve replacements (42.9%), aortic root replacements (19.3%) and right ventricular-pulmonary artery conduits (33.3%). The bank also supplied 23 other centers with homografts (402 aortic and 301 pulmonary). The Bloemfontein bank has established itself over the years as a viable and functional cardiac homograft bank. However, with increasing activity in the procurement arena and widened applications in the operating room the role of the homograft seems assured but availability still remains a major concern.

Anomalous systemic arterial supply to normal basal segment of the left lung.

BACKGROUND: Anomalous systemic arterial supply to normal segments of the lung is an unusual anomaly. It represents part of a spectrum of bronchovascular abnormalities which have various anatomical and clinical manifestations. METHODS: We retrospectively analysed cases from January 2007 to April 2010 from two institutions diagnosed with an anomalous systemic arterial supply to a normal lung segment. RESULTS: Three infants were found to have anomalous systemic arterial supply to normal segments of the lung. One patient was from The Children's Hospital at Westmead, Australia and two cases from Amrita Institute of Medical Sciences, Kochi, India. The mean age at diagnosis was 65 days (range 30-120 days) and mean weight was 3.05 kg (range 1.9-4.4 kg). All babies presented with tachypnoea. The diagnosis was suspected on echocardiography and confirmed by computerised tomography scan (CT scan) in one and by angiography in two cases. The preterm baby underwent ligation of the anomalous vessel by thoracotomy and other two infants had transcatheter occlusion of the collateral. There was no residual flow on echocardiography in any of the three cases and all have done well on follow up. CONCLUSION: Anomalous systemic arterial supply to normal lung segments is a very rare anomaly. A high index of suspicion is needed to expedite diagnosis. Transcatheter embolisation or surgical ligation of the collateral proved effective therapeutic approaches in young infants without a need for surgical lobectomy.

Decline in arterial partial pressure of oxygen after exercise: a surrogate marker of pulmonary vascular obstructive disease in patients with atrial septal defect and severe pulmonary hypertension.

OBJECTIVES: To examine the utility of decline in arterial partial pressure of oxygen after exercise as a marker of pulmonary vascular obstructive disease in patients with atrial septal defect and pulmonary hypertension. METHODS: Treadmill exercise was performed in 18 patients with atrial septal defect and pulmonary hypertension. Arterial blood gas samples were obtained before and after peak exercise. A decline in the arterial pressure of oxygen of more than 10 millimetres of mercury after exercise was considered significant based on preliminary tests conducted on the controls. Cardiac catheterisation was performed in all patients and haemodynamic data sets were obtained on room air, oxygen, and a mixture of oxygen and nitric oxide (30-40 parts per million). RESULTS: There were 10 patients who had more than a 10 millimetres of mercury drop in arterial partial pressure of oxygen after exercise and who had a basal pulmonary vascular resistance index of more than 7 Wood units per square metre. Out of eight patients who had less than a 10 millimetres of mercury drop in arterial partial pressure of oxygen after exercise, seven had a basal pulmonary vascular resistance index of less than 7 Wood units per square metre, p equals 0.0001. A decline in arterial partial pressure of oxygen of more than 10 millimetres of mercury predicted a basal pulmonary vascular resistance index of more than 7 Wood units per square metre with a specificity of 100% and a sensitivity of 90%. CONCLUSIONS: A decline in arterial partial pressure of oxygen following exercise appears to predict a high pulmonary vascular resistance index in patients with atrial septal defect and pulmonary hypertension. This test is a useful non-invasive marker of pulmonary vascular obstructive disease in this subset.