Cardiac surgery for radiation associated heart disease in Hodgkin lymphoma patients.

Much of the modern focus of Hodgkin's Lymphoma (HL) treatment involves the prevention of secondary organ injury. Despite rationalisations of radiotherapy fields, many patients still develop late radiation-related cardiotoxicity that is severe and requires interventional management. No guidelines exist to direct management of these complex patients who often present with multiple concurrent cardiac pathologies. Despite possessing a greater mortality risk than in the general population, cardiac surgery has an important role in treating radiation-associated heart disease. This review summarises the body of literature surrounding cardiac surgery in HL survivors post-radiotherapy, highlighting the benefits and risks unique to this cohort. The pathophysiology and presentation of radiation-associated heart disease is also explored in relation to HL patients.

Multifocal primary intrapulmonary thymoma successfully resected via robotic-assisted thoracoscopic surgery.

Primary intrapulmonary thymoma (PIT) represents a rare subset of ectopic thymoma that arises solely from inside the pulmonary parenchyma. Multifocal PIT, where multiple isolated PIT origins coexist in the lungs, has only been confirmed in one previous case report, in which the patient died before surgical resection. These tumours are difficult to diagnose as imaging findings are non-specific, and non-invasive biopsy often yields inaccurate results. We present the case of a man in his 70s who was referred to thoracic surgery for resection of a presumptive endobronchial pulmonary carcinoid tumour. Only after surgical resection did we identify that the patient had multifocal PIT. In this report, we describe our diagnostic and management process for this patient and review the current literature on PIT.

The role of cardiac surgery in radiation-associated heart disease: a scoping review.

BACKGROUND: Thoracic irradiation is an important tool in the treatment of breast cancer, non-Hodgkin's lymphoma, and other cancers of the chest. The heart is commonly involved in these radiation fields, and young patients can present with severe cardiac pathologies requiring surgical intervention. However, this population poses a high surgical risk due to involvement of mediastinal tissues, and there are no consensus guidelines on best practice management. AIM: This review aims to summarise the current experience of surgical correction of radiation-associated heart disease. We explore outcomes, technique modifications and alternative therapies for the three primary procedures performed: coronary artery bypass grafting, valvular intervention and pericardiectomy. METHODS: OVID Medline and PubMed databases were comprehensively searched to identify all studies involving surgery in patients with prior chest radiotherapy. All relevant studies within the past 25 years have been discussed. CONCLUSION: Irradiated patients have heightened peri-operative risk, but other than redo surgery, these operations are not as treacherous as once thought. Involvement of all layers of the heart, especially the myocardium, is such that long-term mortality suffers despite optimal surgical correction. The goal of surgery in this cohort should be for a quick and safe operation, rather than a technically difficult procedure aimed at longevity.

Coronary Artery Bypass Grafting in Dialysis-Dependent Patients - Key Peri-Operative Considerations.

Cardiovascular disease represents the leading cause of mortality in dialysis-dependent (DD) patients, with the great majority of these patients afflicted by severe coronary artery disease. As rates of end-stage renal disease increase worldwide, DD patients represent a growing proportion of the coronary artery bypass grafting (CABG) cohort. Yet, these patients are complex, with crucial changes in their haemodynamic and physiologic profiles that complicate revascularisation surgery. First, this comprehensive literature review explores the outcomes and prognostic factors for DD patients undergoing CABG. We then summarise the intricacies relating to important peri-operative decisions such as use of cardio-pulmonary bypass and choice of conduit.

Improving survival after pulmonary metastasectomy for sarcoma: analysis of prognostic factors.

BACKGROUND: Metastatic sarcoma confers a grave prognosis to patients and poses a management dilemma for clinicians. Pulmonary metastasectomy is frequently performed for the recurrence of sarcomatous tumours in the lung, but the evidence-base is poor. No guidelines exist to inform clinicians on appropriate patient selection and surgical technique. AIM: This review aims to establish and analyse the most important prognostic factors for survival post pulmonary metastasectomy for recurrent sarcoma. We summarise the key tumour, peri-operative and patient characteristics that should guide surgical management. METHODS: A comprehensive search of the literature utilising OVID Medline and PubMed databases was conducted to identify all relevant research within the past 15 years. We evaluated all articles that specifically studied sarcoma patients (both bone and soft tissue). CONCLUSION: Disease-free interval and tumour burden remain important prognostic factors, while tumour grade is likely not significant. VATS is a safe and viable alternative to thoracotomy without sacrificing survival outcomes. No single peri-operative characteristic provides useful prognostic information in isolation.

Review of bioprosthetic structural valve deterioration: Patient or valve?

BACKGROUND: With guidelines progressively recommending bioprosthetic aortic valves in younger patients, a greater emphasis is placed on structural valve deterioration (SVD) as an important clinical endpoint for both transcatheter and surgically implanted valves. However, SVD of bioprosthetic valves is a complex entity with varying definitions in the literature and a multifaceted pathogenesis. AIM: This review first aims to establish the most updated definitions of SVD as per the literature. We then explore the patient- and valve-related factors that play the greatest roles in facilitating early SVD. METHODS: A PubMed literature review was conducted to identify the relevant research in this field within the past two decades. CONCLUSION: Increasing rates of obesity and metabolic syndrome pose a significant risk to the longevity of bioprosthetic valves. Additionally, externally mounted valves have proven to sacrifice durability for superior haemodynamics. Bioprosthetic SVD continues to be a multifactorial issue that will require various patient- and valve-related factors to be addressed.

Application of a computational model in simulating an endovascular clot retrieval service system within regional Australia.

INTRODUCTION: The global demand for endovascular clot retrieval (ECR) has grown rapidly in recent years creating challenges to healthcare system planning and resource allocation. This study aims to apply our established computational model to predict and optimise the performance and resource allocation of ECR services within regional Australia, and applying data from the state of South Australia as a modelling exercise. METHOD: Local geographic information obtained using the Google Maps application program interface and real-world data was input into the discrete event simulation model we previously developed. The results were obtained after the simulation was run over 5 years. We modelled and compared a single-centre and two-centre ECR service delivery system. RESULTS: Based on the input data, this model was able to simulate the ECR delivery system in the state of South Australia from the moment when emergency services were notified of a potential stroke patient to potential delivery of ECR treatment. In the model, ECR delivery improved using a two-centre system compared to a one-centre system, as the percentage of stroke patients requiring ECR was increased. When 15% of patients required ECR, the proportion of 'failure to receive ECR' cases for a single-centre system was 17.35%, compared to 3.71% for a two-centre system. CONCLUSIONS: Geolocation and resource utilisation within the ECR delivery system are crucial in optimising service delivery and patient outcome. Under the model assumptions, as the number of stroke cases requiring ECR increased, a two-centre ECR system resulted in increased timely ECR delivery, compared to a single-centre system. This study demonstrated the flexibility and the potential application of our DES model in simulating the stroke service within any location worldwide.

Geographic Service Delivery for Endovascular Clot Retrieval: Using Discrete Event Simulation to Optimize Resources.

BACKGROUND: Endovascular clot retrieval (ECR) is the standard of care for acute ischemic stroke caused by large vessel occlusion. Reducing stroke symptom onset to reperfusion time is associated with improved functional outcomes. This study aims to develop a computational model to predict and identify time-related outcomes of community stroke calls within a geographic area based on variable parameters to support planning and coordination of ECR services. METHODS: A discrete event simulation (DES) model to simulate and predict ECR service was designed using SimPy, a process-based DES framework written in Python. Geolocation data defined by the user, as well as that used by the model, were sourced using the Google Maps application programming interface. Variables were customized by the user on the basis of their local environment to provide more accurate prediction. RESULTS: A DES model can estimate the delay between the time that emergency services are notified of a potential stroke and potential cerebral reperfusion using ECR at a capable hospital. Variables can be adjusted to observe the effect of modifying each parameter input. By varying the percentage of stroke patients receiving ECR, we were able to define the levels at which our existing service begins to fail in service delivery and assess the effect of adding centers. CONCLUSIONS: This novel computational DES model can aid the optimization of delivery of a stroke service within a city, state, or country. By varying geographic, population, and other user-defined inputs, the model can be applied to any location worldwide.

CODE STROKE ALERT-Concept and Development of a Novel Open-Source Platform to Streamline Acute Stroke Management.

Introduction: Effective, time-critical intervention in acute stroke is crucial to mitigate mortality rate and morbidity, but delivery of reperfusion treatments is often hampered by pre-, in-, or inter-hospital system level delays. Disjointed, repetitive, and inefficient communication is a consistent contributor to avoidable treatment delay. In the era of rapid reperfusion therapy for ischemic stroke, there is a need for a communication system to synchronize the flow of clinical information across the entire stroke journey. Material/Methods: A multi-disciplinary development team designed an electronic communications platform, integrated between web browsers and a mobile application, to link all relevant members of the stroke treatment pathway. The platform uses tiered notifications, geotagging, incorporates multiple clinical score calculators, and is compliant with security regulations. The system safely saves relevant information for audit and research. Results: Code Stroke Alert is a platform that can be accessed by emergency medical services (EMS) and hospital staff, coordinating the flow of information during acute stroke care, reducing duplication, and error in clinical information handover. Electronic data logs provide an auditable trail of relevant quality improvement metrics, facilitating quality improvement, and research. Discussion: Code Stroke Alert will be freely available to health networks globally. The open-source nature of the software offers valuable potential for future development of plug-ins and add-ons, based on individual institutional needs. Prospective, multi-site implementation, and measurement of clinical impact are underway.

Free flap failure secondary to dual thrombophilia.

Much has been learned over the past several decades regarding thrombophilic conditions. Thrombotic complications, such as deep venous thrombosis, pulmonary embolus, myocardial infarction, and stroke, are sometimes attributed to a diagnosable thrombophilia. Less has been written with regard to their effect on reconstructive outcomes. Fortunately, it is rare to encounter a notable intraoperative thrombophilia while performing reconstructive microsurgery. When this does occur, salvage can be difficult and outcome can be compromised. It is imperative that microsurgeons be knowledgeable of both major and minor thrombogenic conditions to optimize intraoperative outcome and postoperative care. We present a case of a failed free flap for lower extremity reconstruction associated with hyperhomocysteinemia in conjunction with markedly elevated Factor VIII levels.

Rapamycin-coated expanded polytetrafluoroethylene bypass grafts exhibit decreased anastomotic neointimal hyperplasia in a porcine model.

OBJECTIVE: We tested the hypothesis that rapamycin coated onto, and eluted from, expanded polytetrafluoroethylene (ePTFE) grafts would diminish neointimal hyperplasia in a porcine model. METHODS: Rapamycin (also called sirolimus) was coated onto the luminal surface of 6-mm-internal-diameter thin-walled ePTFE grafts by using an adhesive polymer that allows timed release of the drug. An adhesive polymer that allows timed release of rapamycin from ePTFE was developed with commercially available chemicals and applied on 6-mm ePTFE grafts. Graft integrity was characterized by scanning electron microscopy, and rapamycin levels were quantified by using high-performance liquid chromatography. Twenty-two mongrel pigs were randomized into three groups: untreated ePTFE (n = 6), adhesive-only coated ePTFE (n = 6), or adhesive- and rapamycin-coated ePTFE (n = 10). End-to-side unilateral aortoiliac bypasses were performed by using 6-mm-internal-diameter ePTFE grafts and standardized anastomotic lengths. Unilateral end-to-side aortoiliac ePTFE grafts (6-mm internal diameter) were inserted by using polypropylene sutures, 6-0 proximally and 7-0 distally; all anastomoses were 12 mm long. All animals received aspirin (325 mg orally) daily. All animals were given oral aspirin (325 mg) daily beginning on the day before surgery. At 28 days, the animals were killed, and the grafts were explanted in continuity with the adjacent aortic cuff and the outflow iliac artery. Variables compared between groups included graft patency, distal anastomotic length and cross-sectional narrowing, and intimal thickness at the arterial-graft junction indexed to the adjacent graft thickness. Microscopic analysis was performed with hematoxylin and eosin and Masson trichrome stains on paraffin sections. A pathologist blinded to experimental groups graded sections for collagen deposition, neointima formation, inflammatory cellular infiltrates, medial necrosis, and aneurysmal degeneration. RESULTS: All animals survived until they were killed without clinical evidence of limb ischemia or graft infection. Preplanned t tests in the context of one-way analysis of variance showed no difference in outcome measures between the untreated ePTFE and adhesive-only coated ePTFE groups; therefore, they were combined in further comparisons with the adhesive- and rapamycin-coated ePTFE group. The Rapamycine eluting expanded polytetrafluoroethylene group had longer anastomoses (85.6% vs 60.6% of the initial anastomotic length maintained; P < .0001) and less cross-sectional narrowing in the outflow graft (16.2% vs 28.5%; P = .0007) when compared with the other two groups by using two-tailed Student t tests. There was no evidence of medial necrosis or aneurysmal degeneration. All patent grafts had complete endothelialization on hematoxylin and eosin sections. Rapamycin was detectable and quantifiable in the arterial wall at 28 days after implantation. CONCLUSIONS: Rapamycin can be coated onto and eluted from ePTFE by using a nonionic polymer and a simple coating technique. At 4 weeks after implantation, the rapamycin-eluting ePTFE grafts demonstrate gross, pathologic, and morphometric features of diminished neointimal hyperplasia when compared with non-drug-eluting ePTFE. Four weeks after implantation in a porcine model, rapamycin-eluting ePTFE grafts demonstrated gross, pathologic, and morphometric features of diminished neointimal hyperplasia when compared with untreated and adhesive-only coated ePTFE grafts. CLINICAL RELEVANCE: Rapamycin-eluting ePTFE grafts decrease neointimal hyperplasia in a porcine model. Further studies are needed to evaluate whether patency will be improved. Rapamycin-eluting ePTFE grafts may allow the use of prosthetic grafts in situations in which autologous vein is unavailable and in which neointimal hyperplasia is pronounced, such as in small-diameter (<6-mm) vessels typical of infrapopliteal interventions.

Comparison of small-intestinal submucosa and expanded polytetrafluoroethylene as a vascular conduit in the presence of gram-positive contamination.

OBJECTIVE: As a vascular conduit, expanded polytetrafluoroethylene (ePTFE) is susceptible to graft infection with Gram-positive organisms. Biomaterials, such as porcine small-intestinal submucosa (SIS), have been successfully used clinically as tissue substitutes outside the vascular arena. SUMMARY BACKGROUND DATA: In the present study, we compared a small-diameter conduit of SIS to ePTFE in the presence of Gram-positive contamination to evaluate infection resistance, incorporation and remodeling, morphometry, graft patency, and neointimal hyperplasia (NH) development. METHODS: Adult male mongrel pigs were randomized to receive either SIS or ePTFE (3-cm length, 6-mm diameter) and further randomized to 1 of 3 groups: Control (no graft inoculation), Staphylococcus aureus, or mucin-producing S epidermidis (each graft inoculation with 10 colonies/mL). Pressure measurements were obtained proximal and distal to the graft to create the iliac/aorta pressure ratio. Morphometric analysis of the neointima and histopathologic examinations was performed. Other outcomes included weekly WBC counts, graft incorporation, and quantitative culture of explanted grafts. RESULTS: Eighteen animals were randomized. All grafts were patent throughout the 6-week study period. Infected SIS grafts had less NH and little change in their iliac/aorta indices compared with infected ePTFE grafts. Quantitative cultures at euthanasia demonstrated no growth in either SIS group compared with 1.7 x 10(4) colonies for ePTFE S aureus and 6 x 10(2) for ePTFE S epi (each P < 0.001). All SIS grafts were incorporated. Histology demonstrated remodeling into host artery with smooth muscle and capillary ingrowth in all SIS groups. Scanning electron micrography illustrated smooth and complete endothelialization of all SIS grafts. CONCLUSIONS: Compared with ePTFE, SIS induces host tissue remodeling, exhibits a decreased neointimal response to infection, and is resistant to bacterial colonization. SIS may provide a superior alternative to ePTFE as a vascular conduit for peripheral vascular surgery.

Small intestinal submucosa for vascular reconstruction in the presence of gastrointestinal contamination.

INTRODUCTION: Surgical options for vascular reconstruction in a contaminated field are limited and include prosthetic reconstruction or ligation with extra-anatomic bypass. With prosthetic insertion, rates of graft infection and failures (pseudoaneurysms and thrombosis) are high. In the emergent situations, extra-anatomic bypass is time-consuming and complex, and it produces marginal long-term results. Small intestinal submucosa (SIS) is a cell-free collagen matrix derived from porcine small intestine. Preliminary studies have demonstrated its ability to be remodeled into host tissue. In this study, we compared SIS to polytetrafluoroethylene (PTFE) as a vascular patch for arterial repair in the presence of massive gastrointestinal contamination to evaluate graft patency, incorporation, infection, and aneurysm formation. METHODS: Adult mongrel pigs underwent general anesthesia with Isoflurane and were then randomized to 1 of 3 groups: control, contamination (colon puncture with stool contamination of the pelvis), or shock + contamination (40% blood volume for 1 hour, then resuscitation with shed blood and crystalloid, plus contamination). All groups then underwent a left common iliac arteriotomy and further randomized to a 1 x 3-cm patch angioplasty with either SIS or PTFE. All received cefotetan for 24 hours. All animals were sacrificed between 2 and 4 weeks, and necropsy was performed. Grafts were cultured, and microscopic analysis with hematoxylin and eosin and trichrome was performed. Outcomes included pulse quality (normal or diminished) compared with opposite side, graft infection, and pseudoaneurysm; all were determined by a blinded investigator. RESULTS: Forty animals were randomized, and 1 died of abdominal sepsis. All control animals had normal distal pulses, no pseudoaneurysms, and no patch infections. The pseudoaneurysm rate for the contaminated PTFE patches was 25% compared with 0% in the SIS group (P = 0.09). Patch infection occurred in 73% of all PTFE patches compared with 8% of SIS patches (P < 0.03). Organisms present in the infected grafts included Escherichia coli, Bacteroides species, and other Gram-negative enterics. Histopathology demonstrated the presence of neointima in both SIS and PTFE. Only SIS was completely incorporated, with infiltration of collagen fibrils and lymphocytes. CONCLUSIONS: SIS was associated with improved graft patency, less infection, complete incorporation, and no false aneurysm formation when compared with PTFE. This may be due to its ability to provide a durable scaffold for cellularization and tissue remodeling. This material may offer a superior alternative to more complex vascular reconstruction techniques in contaminated fields.