Alexander P.w.m. Maat - Academia.edu (original) (raw)
Papers by Alexander P.w.m. Maat
A 62-year-old man was referred to our center with a sarcoma of his left chest wall with ingrowth ... more A 62-year-old man was referred to our center with a sarcoma of his left chest wall with ingrowth into the pericardium and transdiaphragmatically into the abdomen. The diagnostic delay for patient was extensive, at approximately 3.5 years. Judging by the tumor size and local ingrowth, on first examination, we considered this tumor to be borderline resectable. The patient was treated with induction radiotherapy, resulting in a relief of pain but no radiological response. He was then re-evaluated with particular attention paid to the (peri)cardial involvement. Magnetic resonance imaging (MRI) showed the heart could move freely, and therefore extended resection and reconstruction of the chest and abdominal wall, pericardium, and diaphragm was performed. The combination of diagnostic delay, the large tumor size, the extensive resection, and the use of a nonrigid material for the reconstruction make this case unique. A computed tomography (CT) scan performed 6 weeks postoperatively showed...
The Annals of Thoracic Surgery
We present a case of a 74-year-old male patient, with a history of a squamous cell carcinoma in t... more We present a case of a 74-year-old male patient, with a history of a squamous cell carcinoma in the left axilla. The patient underwent a multidisciplinary surgical resection through an extended forequarter amputation with thoracic wall resection and reconstruction. With regard to the complexity of the case, 3D virtual reality-based patient-specific reconstructions were used as a supplemental tool to conventional computed tomography-imaging in order to plan the procedure. With this report, we aim to stimulate further research to improve and automate the workflow and to bring virtual and augmented reality reconstructions into the surgical theatre of the future.
European Heart Journal - Digital Health
Aims Increased complexity in cardiac surgery over the last decades necessitates more precise preo... more Aims Increased complexity in cardiac surgery over the last decades necessitates more precise preoperative planning to minimize operating time, to limit the risk of complications during surgery and to aim for the best possible patient outcome. Novel, more realistic, and more immersive techniques, such as three-dimensional (3D) virtual reality (VR) could potentially contribute to the preoperative planning phase. This study shows our initial experience on the implementation of immersive VR technology as a complementary research-based imaging tool for preoperative planning in cardiothoracic surgery. In addition, essentials to set up and implement a VR platform are described. Methods Six patients who underwent cardiac surgery at the Erasmus Medical Center, Rotterdam, The Netherlands, between March 2020 and August 2020, were included, based on request by the surgeon and availability of computed tomography images. After 3D VR rendering and 3D segmentation of specific structures, the recons...
The Annals of thoracic surgery, 2018
The nationwide Dutch Lung Surgery Audit (DLSA) started in 2012 to monitor and evaluate the qualit... more The nationwide Dutch Lung Surgery Audit (DLSA) started in 2012 to monitor and evaluate the quality of lung operations in The Netherlands as an improvement tool. This outline describes the establishment, structure, and organization of the audit by the Dutch Society of Lung Surgeons (NVvL) and the Dutch Society of Cardiothoracic Surgeons (NVT), in collaboration with the Dutch Institute for Clinical Auditing. In addition, the first 4-year results are presented. The NVvL and NVT initiated a web-based registration, including weekly updated online feedback for participating hospitals. Data verification by external data managers is performed on regular basis. The audit is incorporated in national quality improvement programs, and participation in the DLSA is mandatory by health insurance organizations and the National Healthcare Inspectorate. Between January 1, 2012, and December 31, 2015, all hospitals performing lung operations participated, and a total of 19,557 patients were registered...
The Journal of Heart and Lung Transplantation
Cellular oncology (Dordrecht), Jan 2, 2017
There is a lack of robust and clinically utilizable markers for the diagnosis and prognostication... more There is a lack of robust and clinically utilizable markers for the diagnosis and prognostication of malignant pleural mesothelioma (MPM). This research was aimed at optimizing and exploring novel approaches to improve the diagnosis and prognostication of MPM in pleural effusions and peripheral blood samples. CellSearch-based and flow cytometry-based assays using melanoma cell adhesion molecule (MCAM) to identify circulating tumor cells (CTCs) in pleural effusions and peripheral blood samples of MPM patients were optimized, validated, explored clinically and, in case of pleural effusions, compared with cytological analyses. Additionally, tumor-associated circulating endothelial cells (CECs) were measured in peripheral blood samples. The assays were performed on a MPM cohort encompassing patients with histology-confirmed MPM (n=27) and in a control cohort of patients with alternative diagnoses (n=22). Exploratory analyses on the prognostic value of all assays were also performed. The...
American journal of respiratory and critical care medicine, Jan 27, 2017
ASAIO journal (American Society for Artificial Internal Organs : 1992), Jan 21, 2017
Implantable continuous flow left ventricular assist devices (LVAD's) are increasingly used in... more Implantable continuous flow left ventricular assist devices (LVAD's) are increasingly used in end-stage heart failure treatment as a bridge-to-transplant and destination therapy. However, LVAD's still have major drawbacks, such as infections that can cause morbidity and mortality. Unfortunately, appropriate diagnosis of LVAD-related and LVAD-specific infections can be very cumbersome. The differentiation between deep and superficial infections, is crucial in clinical decision-making. Despite a decade of experience in using fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) to diagnose various infections, its use in LVAD patients remains scarce. In this case series, we review the current evidence in literature and describe our single center experience using F-FDG PET/CT for the diagnosis and management of LVAD infections.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives ...
J Heart Lung Transplant, 2001
ABSTRACT
American journal of respiratory and critical care medicine, Jan 14, 2015
We demonstrated before that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in ... more We demonstrated before that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in patients with malignant pleural mesothelioma is feasible, well-tolerated, and capable of inducing immunological responses against tumors. In our murine model we found that reduction of regulatory T cells with metronomic cyclophosphamide increased the efficacy of immunotherapy. To assess the decrease in number of peripheral blood regulatory T cells during combination therapy of low-dose cyclophosphamide and dendritic cell immunotherapy and to determine the induction of immunological responses with this treatment in mesothelioma patients. Ten malignant pleural mesothelioma patients received metronomic cyclophosphamide and dendritic cell-based immunotherapy. During the treatment, peripheral blood mononuclear cells were analyzed for regulatory T cells and immunological responses. Administration of dendritic cells pulsed with autologous tumor lysate combined with cyclophosphamide in mesotheli...
Future Oncology, 2015
Hope is a very important mindset for malignant pleural mesothelioma patients as their cancer has ... more Hope is a very important mindset for malignant pleural mesothelioma patients as their cancer has a grim prognosis and limited therapeutic options. In this paper, we briefly discuss what hope means for a patient and how hope can help to cope with this disease. In addition, we discuss false hope. We also briefly touch on a few of the new therapies currently under development.
Nederlands tijdschrift voor geneeskunde, 2015
Exacerbations of bronchiectasis can result in a decline in lung function, a poorer prognosis and ... more Exacerbations of bronchiectasis can result in a decline in lung function, a poorer prognosis and a reduction in quality of life. Three female patients aged 57, 41 and 40 presented with recurrent exacerbations of bronchiectasis despite optimal conservative and antibiotic (maintenance) treatment. In one patient the underlying cause of the bronchiectasis could not be identified; in the other two patients there was a post infectious cause. Surgical procedures were performed on account of the presence of localised bronchiectasis. No major complications were observed. All three patients experienced an impressive reduction in symptoms and exacerbations. Moreover, there was only a slight decline in lung function in two patients and an improvement in lung function in one patient. In patients with localised bronchiectasis, recurrent exacerbations and persistent symptoms despite optimal conservative and antibiotic treatment, surgical resection of affected areas could reduce the number of exace...
International Journal of Radiation Oncology*Biology*Physics, 2015
A prognostic model for 5-year overall survival (OS), consisting of recursive partitioning analysi... more A prognostic model for 5-year overall survival (OS), consisting of recursive partitioning analysis (RPA) and a nomogram, was developed for patients with early-stage non-small cell lung cancer (ES-NSCLC) treated with stereotactic ablative radiation therapy (SABR). A primary dataset of 703 ES-NSCLC SABR patients was randomly divided into a training (67%) and an internal validation (33%) dataset. In the former group, 21 unique parameters consisting of patient, treatment, and tumor factors were entered into an RPA model to predict OS. Univariate and multivariate models were constructed for RPA-selected factors to evaluate their relationship with OS. A nomogram for OS was constructed based on factors significant in multivariate modeling and validated with calibration plots. Both the RPA and the nomogram were externally validated in independent surgical (n=193) and SABR (n=543) datasets. RPA identified 2 distinct risk classes based on tumor diameter, age, World Health Organization performance status (PS) and Charlson comorbidity index. This RPA had moderate discrimination in SABR datasets (c-index range: 0.52-0.60) but was of limited value in the surgical validation cohort. The nomogram predicting OS included smoking history in addition to RPA-identified factors. In contrast to RPA, validation of the nomogram performed well in internal validation (r(2)=0.97) and external SABR (r(2)=0.79) and surgical cohorts (r(2)=0.91). The Amsterdam prognostic model is the first externally validated prognostication tool for OS in ES-NSCLC treated with SABR available to individualize patient decision making. The nomogram retained strong performance across surgical and SABR external validation datasets. RPA performance was poor in surgical patients, suggesting that 2 different distinct patient populations are being treated with these 2 effective modalities.
Transplantation, Jan 16, 2015
FOXP3+ regulatory T cells (Treg) either originate in the thymus (natural [n]Treg) or are induced ... more FOXP3+ regulatory T cells (Treg) either originate in the thymus (natural [n]Treg) or are induced in the periphery by antigen exposure and cytokines (induced [i]Treg). It is currently not elucidated which and to what extent these Treg subsets regulate intracardiac allogeneic responses in transplant patients. By using demethylation of the Treg-specific demethylated region in the FOXP3 gene as a marker for nTreg and FOXP3 messenger RNA expression as a marker for the total Treg population, we examined Treg in endomyocardial biopsies (EMBs) of both patients who developed an acute rejection necessitating therapy (rejectors; International Society for Heart and Lung Transplantation rejection grade ≥ 2R) and patients who remained free from rejection (nonrejectors). In the presence of comparable messenger RNA levels of CD3, IL-10, TGFβ, IL2, IFNγ, and IL17A, the percentage of nTreg was significantly higher in EMB with histological signs of mild rejection (rejection grade 1R) collected before ...
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, Jan 16, 2015
Mechanical circulatory support (MCS) with a ventricular assist device (VAD) as a bridge to heart ... more Mechanical circulatory support (MCS) with a ventricular assist device (VAD) as a bridge to heart transplantation (HTx) or recovery may improve outcome in children with terminal heart failure. We report our experience with MCS in children eligible for HTx and its effect on waiting list mortality. Retrospective single-centre cohort study, National Paediatric HTx Programme including all children eligible for HTx, since the introduction of MCS-VAD in 2006. A total of 43 patients were eligible for HTx, median age 11.7 years [Inter Quartile Range (IQR) 3.0-14.7]. In 18 patients, (42%) a VAD was implanted, 11 (61%) survived to HTx (n = 9) or recovery (n = 2). Techniques and devices used were left ventricular assist device (n = 16, 89%), in 4 cases preceded by extracorporeal membrane oxygenation (ECMO), and biventricular assist device (n = 2, 11%), both preceded by ECMO. In the VAD group, median time to death (n = 7) was 18 days (IQR 7-75), median time to HTx (n = 9) 66 days (IQR 33-223) an...
Paediatric anaesthesia, 2011
A 62-year-old man was referred to our center with a sarcoma of his left chest wall with ingrowth ... more A 62-year-old man was referred to our center with a sarcoma of his left chest wall with ingrowth into the pericardium and transdiaphragmatically into the abdomen. The diagnostic delay for patient was extensive, at approximately 3.5 years. Judging by the tumor size and local ingrowth, on first examination, we considered this tumor to be borderline resectable. The patient was treated with induction radiotherapy, resulting in a relief of pain but no radiological response. He was then re-evaluated with particular attention paid to the (peri)cardial involvement. Magnetic resonance imaging (MRI) showed the heart could move freely, and therefore extended resection and reconstruction of the chest and abdominal wall, pericardium, and diaphragm was performed. The combination of diagnostic delay, the large tumor size, the extensive resection, and the use of a nonrigid material for the reconstruction make this case unique. A computed tomography (CT) scan performed 6 weeks postoperatively showed...
The Annals of Thoracic Surgery
We present a case of a 74-year-old male patient, with a history of a squamous cell carcinoma in t... more We present a case of a 74-year-old male patient, with a history of a squamous cell carcinoma in the left axilla. The patient underwent a multidisciplinary surgical resection through an extended forequarter amputation with thoracic wall resection and reconstruction. With regard to the complexity of the case, 3D virtual reality-based patient-specific reconstructions were used as a supplemental tool to conventional computed tomography-imaging in order to plan the procedure. With this report, we aim to stimulate further research to improve and automate the workflow and to bring virtual and augmented reality reconstructions into the surgical theatre of the future.
European Heart Journal - Digital Health
Aims Increased complexity in cardiac surgery over the last decades necessitates more precise preo... more Aims Increased complexity in cardiac surgery over the last decades necessitates more precise preoperative planning to minimize operating time, to limit the risk of complications during surgery and to aim for the best possible patient outcome. Novel, more realistic, and more immersive techniques, such as three-dimensional (3D) virtual reality (VR) could potentially contribute to the preoperative planning phase. This study shows our initial experience on the implementation of immersive VR technology as a complementary research-based imaging tool for preoperative planning in cardiothoracic surgery. In addition, essentials to set up and implement a VR platform are described. Methods Six patients who underwent cardiac surgery at the Erasmus Medical Center, Rotterdam, The Netherlands, between March 2020 and August 2020, were included, based on request by the surgeon and availability of computed tomography images. After 3D VR rendering and 3D segmentation of specific structures, the recons...
The Annals of thoracic surgery, 2018
The nationwide Dutch Lung Surgery Audit (DLSA) started in 2012 to monitor and evaluate the qualit... more The nationwide Dutch Lung Surgery Audit (DLSA) started in 2012 to monitor and evaluate the quality of lung operations in The Netherlands as an improvement tool. This outline describes the establishment, structure, and organization of the audit by the Dutch Society of Lung Surgeons (NVvL) and the Dutch Society of Cardiothoracic Surgeons (NVT), in collaboration with the Dutch Institute for Clinical Auditing. In addition, the first 4-year results are presented. The NVvL and NVT initiated a web-based registration, including weekly updated online feedback for participating hospitals. Data verification by external data managers is performed on regular basis. The audit is incorporated in national quality improvement programs, and participation in the DLSA is mandatory by health insurance organizations and the National Healthcare Inspectorate. Between January 1, 2012, and December 31, 2015, all hospitals performing lung operations participated, and a total of 19,557 patients were registered...
The Journal of Heart and Lung Transplantation
Cellular oncology (Dordrecht), Jan 2, 2017
There is a lack of robust and clinically utilizable markers for the diagnosis and prognostication... more There is a lack of robust and clinically utilizable markers for the diagnosis and prognostication of malignant pleural mesothelioma (MPM). This research was aimed at optimizing and exploring novel approaches to improve the diagnosis and prognostication of MPM in pleural effusions and peripheral blood samples. CellSearch-based and flow cytometry-based assays using melanoma cell adhesion molecule (MCAM) to identify circulating tumor cells (CTCs) in pleural effusions and peripheral blood samples of MPM patients were optimized, validated, explored clinically and, in case of pleural effusions, compared with cytological analyses. Additionally, tumor-associated circulating endothelial cells (CECs) were measured in peripheral blood samples. The assays were performed on a MPM cohort encompassing patients with histology-confirmed MPM (n=27) and in a control cohort of patients with alternative diagnoses (n=22). Exploratory analyses on the prognostic value of all assays were also performed. The...
American journal of respiratory and critical care medicine, Jan 27, 2017
ASAIO journal (American Society for Artificial Internal Organs : 1992), Jan 21, 2017
Implantable continuous flow left ventricular assist devices (LVAD's) are increasingly used in... more Implantable continuous flow left ventricular assist devices (LVAD's) are increasingly used in end-stage heart failure treatment as a bridge-to-transplant and destination therapy. However, LVAD's still have major drawbacks, such as infections that can cause morbidity and mortality. Unfortunately, appropriate diagnosis of LVAD-related and LVAD-specific infections can be very cumbersome. The differentiation between deep and superficial infections, is crucial in clinical decision-making. Despite a decade of experience in using fluorodeoxyglucose positron emission tomography/computed tomography (F-FDG PET/CT) to diagnose various infections, its use in LVAD patients remains scarce. In this case series, we review the current evidence in literature and describe our single center experience using F-FDG PET/CT for the diagnosis and management of LVAD infections.This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives ...
J Heart Lung Transplant, 2001
ABSTRACT
American journal of respiratory and critical care medicine, Jan 14, 2015
We demonstrated before that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in ... more We demonstrated before that autologous tumor lysate-pulsed dendritic cell-based immunotherapy in patients with malignant pleural mesothelioma is feasible, well-tolerated, and capable of inducing immunological responses against tumors. In our murine model we found that reduction of regulatory T cells with metronomic cyclophosphamide increased the efficacy of immunotherapy. To assess the decrease in number of peripheral blood regulatory T cells during combination therapy of low-dose cyclophosphamide and dendritic cell immunotherapy and to determine the induction of immunological responses with this treatment in mesothelioma patients. Ten malignant pleural mesothelioma patients received metronomic cyclophosphamide and dendritic cell-based immunotherapy. During the treatment, peripheral blood mononuclear cells were analyzed for regulatory T cells and immunological responses. Administration of dendritic cells pulsed with autologous tumor lysate combined with cyclophosphamide in mesotheli...
Future Oncology, 2015
Hope is a very important mindset for malignant pleural mesothelioma patients as their cancer has ... more Hope is a very important mindset for malignant pleural mesothelioma patients as their cancer has a grim prognosis and limited therapeutic options. In this paper, we briefly discuss what hope means for a patient and how hope can help to cope with this disease. In addition, we discuss false hope. We also briefly touch on a few of the new therapies currently under development.
Nederlands tijdschrift voor geneeskunde, 2015
Exacerbations of bronchiectasis can result in a decline in lung function, a poorer prognosis and ... more Exacerbations of bronchiectasis can result in a decline in lung function, a poorer prognosis and a reduction in quality of life. Three female patients aged 57, 41 and 40 presented with recurrent exacerbations of bronchiectasis despite optimal conservative and antibiotic (maintenance) treatment. In one patient the underlying cause of the bronchiectasis could not be identified; in the other two patients there was a post infectious cause. Surgical procedures were performed on account of the presence of localised bronchiectasis. No major complications were observed. All three patients experienced an impressive reduction in symptoms and exacerbations. Moreover, there was only a slight decline in lung function in two patients and an improvement in lung function in one patient. In patients with localised bronchiectasis, recurrent exacerbations and persistent symptoms despite optimal conservative and antibiotic treatment, surgical resection of affected areas could reduce the number of exace...
International Journal of Radiation Oncology*Biology*Physics, 2015
A prognostic model for 5-year overall survival (OS), consisting of recursive partitioning analysi... more A prognostic model for 5-year overall survival (OS), consisting of recursive partitioning analysis (RPA) and a nomogram, was developed for patients with early-stage non-small cell lung cancer (ES-NSCLC) treated with stereotactic ablative radiation therapy (SABR). A primary dataset of 703 ES-NSCLC SABR patients was randomly divided into a training (67%) and an internal validation (33%) dataset. In the former group, 21 unique parameters consisting of patient, treatment, and tumor factors were entered into an RPA model to predict OS. Univariate and multivariate models were constructed for RPA-selected factors to evaluate their relationship with OS. A nomogram for OS was constructed based on factors significant in multivariate modeling and validated with calibration plots. Both the RPA and the nomogram were externally validated in independent surgical (n=193) and SABR (n=543) datasets. RPA identified 2 distinct risk classes based on tumor diameter, age, World Health Organization performance status (PS) and Charlson comorbidity index. This RPA had moderate discrimination in SABR datasets (c-index range: 0.52-0.60) but was of limited value in the surgical validation cohort. The nomogram predicting OS included smoking history in addition to RPA-identified factors. In contrast to RPA, validation of the nomogram performed well in internal validation (r(2)=0.97) and external SABR (r(2)=0.79) and surgical cohorts (r(2)=0.91). The Amsterdam prognostic model is the first externally validated prognostication tool for OS in ES-NSCLC treated with SABR available to individualize patient decision making. The nomogram retained strong performance across surgical and SABR external validation datasets. RPA performance was poor in surgical patients, suggesting that 2 different distinct patient populations are being treated with these 2 effective modalities.
Transplantation, Jan 16, 2015
FOXP3+ regulatory T cells (Treg) either originate in the thymus (natural [n]Treg) or are induced ... more FOXP3+ regulatory T cells (Treg) either originate in the thymus (natural [n]Treg) or are induced in the periphery by antigen exposure and cytokines (induced [i]Treg). It is currently not elucidated which and to what extent these Treg subsets regulate intracardiac allogeneic responses in transplant patients. By using demethylation of the Treg-specific demethylated region in the FOXP3 gene as a marker for nTreg and FOXP3 messenger RNA expression as a marker for the total Treg population, we examined Treg in endomyocardial biopsies (EMBs) of both patients who developed an acute rejection necessitating therapy (rejectors; International Society for Heart and Lung Transplantation rejection grade ≥ 2R) and patients who remained free from rejection (nonrejectors). In the presence of comparable messenger RNA levels of CD3, IL-10, TGFβ, IL2, IFNγ, and IL17A, the percentage of nTreg was significantly higher in EMB with histological signs of mild rejection (rejection grade 1R) collected before ...
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, Jan 16, 2015
Mechanical circulatory support (MCS) with a ventricular assist device (VAD) as a bridge to heart ... more Mechanical circulatory support (MCS) with a ventricular assist device (VAD) as a bridge to heart transplantation (HTx) or recovery may improve outcome in children with terminal heart failure. We report our experience with MCS in children eligible for HTx and its effect on waiting list mortality. Retrospective single-centre cohort study, National Paediatric HTx Programme including all children eligible for HTx, since the introduction of MCS-VAD in 2006. A total of 43 patients were eligible for HTx, median age 11.7 years [Inter Quartile Range (IQR) 3.0-14.7]. In 18 patients, (42%) a VAD was implanted, 11 (61%) survived to HTx (n = 9) or recovery (n = 2). Techniques and devices used were left ventricular assist device (n = 16, 89%), in 4 cases preceded by extracorporeal membrane oxygenation (ECMO), and biventricular assist device (n = 2, 11%), both preceded by ECMO. In the VAD group, median time to death (n = 7) was 18 days (IQR 7-75), median time to HTx (n = 9) 66 days (IQR 33-223) an...
Paediatric anaesthesia, 2011