Sayed Himmat

University of Alberta | UAlberta · Division of Cardiac Surgery

Background Ischemia/reperfusion injury (IRI) is an inherent problem in organ transplantation, owing to the obligate period of ischemia that organs must endure. Cyclosporine A (CsA), though better know as an immunosuppressant, has been shown to mitigate warm IRI in a variety of organ types, including the liver. However, there is little evidence for...

We sought to determine the role of donor blood circulating leukocytes in mediating oxidative stress and inflammation during normothermic ex situ heart perfusion (ESHP). Normothermic ESHP allows preservation of donated heart in a perfused, dynamic state, preventing ischemia. However, the cardiac function declines during ESHP, limiting the potential...

BACKGROUND Evidence suggests that hearts that are perfused under ex-situ conditions lose normal coronary vasomotor tone and experience contractile failure over a few hours. We aimed to evaluate the effect of different coronary perfusion strategies during ex situ heart perfusion on cardiac function and coronary vascular tone. METHODS Porcine hearts...

BACKGROUND von Willebrand factor (VWF) is a pro-coagulant glycoprotein expressed only in endothelial cells and megakaryocytes. It plays a critical role in hemostasis and thrombus formation. It mediates the adhesion of platelets to the endothelium/sub-endothelium surfaces, which is the primary step in thrombogenesis. Our previous analyses demonstrat...

Purpose Ex-situ heart perfusion (ESHP) allows continuous functional and metabolic resuscitation of donor hearts before transplantation. Evidence indicates that hearts that are perfused under physiologic conditions lose the normal vasomotor tone and fail in a few hours. We aim to evaluate the reduced coronary flow during ex situ heart perfusion on c...

Ex situ heart perfusion (ESHP) is being investigated as a method for the continuous preservation of the myocardium in a semiphysiologic state for subsequent transplantation. Most methods of ESHP position the isolated heart in a hanging (H) state, representing a considerable departure from the in vivo anatomical positioning of the heart and may nega...

Although lung transplant remains the only option for patients with end-stage lung failure, short preservation times result in an inability to meet patient demand. Successful cryopreservation may ameliorate this problem; however, very little research has been performed on lung cryopreservation due to the inability to prevent ice nucleation or growth...

Background Normothermic ex vivo lung perfusion (EVLP) has been used successfully to evaluate and recondition marginal donor lungs; however, multiple barriers continue to prevent its widespread adoption. We sought to develop a common hospital ingredient-derived perfusate (CHIP) with equivalent functional and inflammatory characteristics to a standar...

Background: Ex situ heart perfusion (ESHP) preserves the donated heart in a perfused, beating condition preventing cold storage-related ischemia and provides a platform to evaluate myocardial viability during preservation. However, myocardial function declines gradually during ESHP. Extracorporeal circulation systems are associated with the induct...

Purpose Ex-situ heart perfusion preserves the donated heart in a perfused and semi-physiologic condition preventing preservation-related ischemia however, myocardial function declines overtime in this setting. All models of ex-situ heart perfusion (ESHP) position the heart in a suspended state which is at considerable variance with the in vivo posi...

Purpose Ex situ heart perfusion (ESHP) allows continuous functional and metabolic assessment of donor hearts before transplantation. Evidence indicates that circulating chemical mediators in whole blood are involved in the regulation of oxygen delivery. We aim to evaluate the impact of whole blood versus dilute whole blood in the regulation of coro...

Ex vivo lung perfusion (EVLP) protocols generally limit metabolic supplementation to insulin and glucose. We sought to determine whether the addition of total parenteral nutrition (TPN) would improve lung function in EVLP. Ten porcine lungs were perfused using EVLP for 24 hours and supplemented with insulin and glucose. In the treatment group (n=5)...

Background: Extended periods of ex vivo lung perfusion (EVLP) lead to several inadvertent consequences including accumulation of lactate and increasing electrolyte concentrations in the perfusate. We sought to determine whether continuous hemodialysis (CHD) of the perfusate would be a suitable modality for improving ionic homeostasis in extended E...

Purpose Extended periods of ex vivo lung perfusion (EVLP) lead to several inadvertent consequences including accumulation of lactate and increasing electrolyte concentrations in the perfusate. Cellular perfusate based systems, such as the OCS Lung and Vivoline LS1, require a membrane-exchange system for electrolyte correction if they are to maintai...

Purpose Ex situ heart perfusion (ESHP) allows continuous functional and metabolic assessment of donor hearts before transplantation. The coronary artery autoregulation is essential to maintain normal cardiac function during ESHP. Our objective is to investigate coronary autoregulation during normothermic ESHP and find ways to protect myocardial fun...

Purpose Ex situ heart perfusion (ESHP) is a novel method for preservation of the donated heart in a semi-physiologic state and provides the opportunity to evaluate pre-transplant function. Because of the well-described extraordinary metabolic requirements of the heart, efficient metabolic support is critical for optimal preservation of function and...

Background Heart transplantation (HTx) is a recognized therapy for terminal heart failure patients; however, it is limited by availability of suitable donors and quality of cardiac grafts. To expand heart donor pool, normothermic ex situ heart perfusion (ESHP) has emerged as a platform for reconditioning marginal donor hearts and consequently incre...

Background: Myocardial function declines in a time-dependent fashion during ex situ heart perfusion. Cell death and metabolic alterations may contribute to this phenomenon, limiting the safe perfusion period and the potential of ex situ heart perfusion to expand the donor pool. Our aim was to investigate the etiology of myocardial functional decli...

The current standard method for organ preservation (cold storage, CS), exposes the heart to a period of cold ischemia that limits the safe preservation time and increases the risk of adverse post-transplantation outcomes. Moreover, the static nature of CS does not allow for organ evaluation or intervention during the preservation interval. Normothe...

Ex vivo lung perfusion (EVLP) shows promise in ameliorating pre-transplant acute lung injury (ALI) and expanding the donor organ pool, but the mechanisms of ex vivo repair remain poorly understood. We aimed to assess the utility of gene expression for characterizing ALI during EVLP. 169 porcine lung samples were collected in vivo (n=25), after 0 (n...

Introduction Heart transplantation remains the standard treatment for advanced heart failure. However, waiting lists for donor heart continue to rise all over the world due to the discrepancy between the demand and supply of suitable organs. Ex‐vivo heart perfusion (EVHP) has been proposed as a means improving heart preservation and expanding the d...

Ex vivo lung perfusion (EVLP) shows promise in ameliorating pre‐transplant acute lung injury (ALI) and expanding the donor organ pool, but the mechanisms of ex vivo repair remain poorly understood. We aimed to assess the utility of gene expression for characterizing ALI during EVLP. 169 porcine lung samples were collected in vivo (n=25), after 0 (n...

Normothermic ex vivo lung perfusion (EVLP) is an evolving technology to evaluate function of donor lungs to determine suitability for transplantation. We hypothesize that hypoxic pulmonary vasoconstriction (HPV) during EVLP will provide a more sensitive parameter of lung function to determine donor lung quality for lung transplantation. Eight porci...

Background: Normothermic ex-vivo lung perfusion (EVLP) using positive pressure ventilation (PPV) and both acellular and red blood cell (RBC)-based perfusate solutions have increased the rate of donor organ utilization. We sought to determine whether a negative pressure ventilation (NPV) strategy would improve donor lung assessment during EVLP. Me...

Background Normothermic ex-vivo lung perfusion (EVLP) using positive pressure ventilation (PPV) and both acellular and red blood cell (RBC)-based perfusate solutions have increased the rate of donor organ utilization. We sought to determine whether a negative pressure ventilation (NPV) strategy would improve donor lung assessment during EVLP. Meth...

Normothermic ex vivo lung perfusion (EVLP) allows for assessment and reconditioning of donor lungs. Though a leukocyte filter (LF) is routinely incorporated into the EVLP circuit, its efficacy remains to be determined. Twelve pig lungs were perfused and ventilated ex vivo in a normothermic state for 12 hours. Lungs (n=3) were allocated to 4 groups...

Background: Brain death, organ procurement and preservation cause acute lung injury (ALI). As a result, only about 20% of donated lungs are suitable for transplantation and a quarter of these develop primary dysfunction. With the recent development of ex vivo perfusion, previously inadequate donor lungs can now potentially be used for transplantati...

Background: Brain death, organ procurement and preservation cause acute lung injury (ALI). As a result, only about 20% of donated lungs are suitable for transplantation and a quarter of these develop primary dysfunction. With the recent development of ex vivo perfusion, previously inadequate donor lungs can now potentially be used for transplantati...

Lung transplantation is an established treatment option for eligible patients with end-stage lung disease. Nonetheless, there exists an imbalance between donor lungs considered suitable for transplantation and the ever-growing number of patients dying on the waiting list. This chapter reflects the potential alternative, normothermic ex-vivo lung pe...