RBCs Regulate Platelet Function and Hemostasis under Shear Conditions through Biophysical and Biochemical Means.

Red blood cells (RBCs) have been hypothesized to support hemostasis by facilitating platelet margination and releasing platelet-activating factors such as adenosine diphosphate (ADP). Significant knowledge gaps remain regarding how RBCs influence platelet function, especially in (patho)physiologically relevant hemodynamic conditions. Here we present results showing how RBCs affect platelet function and hemostasis in conditions of anemia, thrombocytopenia, and pancytopenia, and how the biochemical and biophysical properties of RBCs regulate platelet function at the blood-vessel wall interface and in the fluid phase under flow conditions. We found that RBCs promoted platelet deposition to collagen under flow conditions in moderate (50  103/L) but not severe (10  103/L) thrombocytopenia in vitro. Reduction in hematocrit by 45% led to increased bleeding in mice with hemolytic anemia. In contrast, bleeding diathesis was observed in mice with a 90% but not with a 60% reduction in platelet counts. RBC transfusion improved hemostasis by enhancing fibrin clot formation at the site of vascular injury in mice with severe pancytopenia induced by total body irradiation. Altering membrane deformability changed the ability of RBCs to promote platelet aggregation. RBC-derived ADP contributed to platelet activation and aggregation in vitro under pathologically high shear stresses, as observed in patients supported by left ventricular assist devices. These findings demonstrate that RBCs support platelet function and hemostasis through multiple mechanisms, both at the blood-vessel wall interface and in the fluidic phase of circulation.

Coronary flow capacity and survival prediction after revascularization: physiological basis and clinical implications.

BACKGROUND AND AIMS: Coronary flow capacity (CFC) is associated with an observed 10-year survival probability for individual patients before and after actual revascularization for comparison to virtual hypothetical ideal complete revascularization. METHODS: Stress myocardial perfusion (mL/min/g) and coronary flow reserve (CFR) per pixel were quantified in 6979 coronary artery disease (CAD) subjects using Rb-82 positron emission tomography (PET) for CFC maps of artery-specific size-severity abnormalities expressed as percent left ventricle with prospective follow-up to define survival probability per-decade as fraction of 1.0. RESULTS: Severely reduced CFC in 6979 subjects predicted low survival probability that improved by 42% after revascularization compared with no revascularization for comparable severity (P = .0015). For 283 pre-and-post-procedure PET pairs, severely reduced regional CFC-associated survival probability improved heterogeneously after revascularization (P < .001), more so after bypass surgery than percutaneous coronary interventions (P < .001) but normalized in only 5.7%; non-severe baseline CFC or survival probability did not improve compared with severe CFC (P = .00001). Observed CFC-associated survival probability after actual revascularization was lower than virtual ideal hypothetical complete post-revascularization survival probability due to residual CAD or failed revascularization (P < .001) unrelated to gender or microvascular dysfunction. Severely reduced CFC in 2552 post-revascularization subjects associated with low survival probability also improved after repeat revascularization compared with no repeat procedures (P = .025). CONCLUSIONS: Severely reduced CFC and associated observed survival probability improved after first and repeat revascularization compared with no revascularization for comparable CFC severity. Non-severe CFC showed no benefit. Discordance between observed actual and virtual hypothetical post-revascularization survival probability revealed residual CAD or failed revascularization.

Use of Percutaneous Left Ventricular Assist Device Before Durable Device Implantation in Patients With Cardiac Cachexia: Case Series.

Frailty and malnutrition in patients with heart failure are barriers to durable left ventricular assist device (D-LVAD) support and heart transplantation. Moreover, cachexia in patients with advanced heart failure carries a high mortality risk. There are no guidelines for these patients other than increased caloric intake and rehabilitation. Patients suffering from cardiac cachexia and heart failure may benefit from temporary, percutaneous assist device support to improve the underlying heart disease and reverse the catabolic state. We retrospectively reviewed patients from January 2017 to January 2022. All patients who received Impella support (5.0 or 5.5, Abiomed) before D-LVAD implantation were screened. Those who met the criteria for cardiac cachexia were included. Patient demographics, nutritional and biochemical markers, and survival data were collected. A total of 14 patients were included. The majority of patients were male (85.7%) with ischemic cardiomyopathy (64.3%). Caloric intake, physical strength, and ambulation improved. Prealbumin levels improved from a median of 13.7-18.0 mg/dl ( p < 0.006) while on Impella 5.0 or 5.5 support. All patients survived to discharge and the 6 month follow-up. In conclusion, use of the Impella device improves cardiogenic shock symptoms and, consequently, may improve cachexia status prior to D-LVAD implantation.

Pre- and post-operative mechanical circulatory support in surgical repair of post-acute myocardial infarction mechanical complications.

The outcomes of patients with acute myocardial infarctions (AMI) have significantly improved with advances in early reperfusion strategies; however, patients with massive infarcts or those who do not receive timely revascularization may develop mechanical complications of AMI. The most common mechanical complications are ventricular septal rupture (VSR), acute mitral regurgitation (MR) due to papillary muscle rupture, and free-wall rupture. Each complication is associated with a high risk of morbidity and mortality, and requires a multidisciplinary approach for prompt diagnosis and hemodynamic stabilization. Surgery is the mainstay of therapy but is associated with poor outcomes if performed too early during the treatment course for VSR or if performed too late with MR and free wall rupture. Optimal timing for surgery in combination with temporary circulatory support may be a feasible strategy for better results.

Transcatheter aortic valve implantation with a Sapien 3 Commander 20 mm valves in patients with degenerated 19 mm bioprosthetic aortic valve.

INTRODUCTION: Transcatheter aortic valve implantation (TAVI) in patients with degenerated bioprosthetic aortic valve has been successfully performed as an alternative to surgery. We describe our initial experience of valve-in-valve TAVI in five patients, using new generation Edwards Sapien 3 transcatheter heart valves implanted into degenerated 19 mm bioprosthetic valves. 20-mm Edwards S3 valves were offered for compassionate use. All patients had significant aortic valve stenosis. METHODS AND RESULTS: The main vascular access was achieved and pre-closed with two Proglide closure devices in one patient and Prostar closure devices in four patients. For each TAVI procedure an Edwards 14 French sheath was inserted without complication and sutured in place. The Sapien 3 Commander delivery system was inserted and the valve was aligned in the descending aorta. The 20-mm Sapien 3 valve was deployed with slow continuous inflation during rapid right ventricular pacing. The cranial edge of the Edwards S3 valve was aligned with the cranial radiopaque markers of bioprosthesis to minimize paravalvular leak. Post-deployment angiography, transesophageal echocardiography and aortogram confirmed absence of mild aortic insufficiency and no increase in trans-aortic gradient when compared to a naïve 19 mm bioprosthetic valve. CONCLUSION: Valve-in-valve TAVI with the Edwards S3 transcatheter heart valve for degenerative bioprosthetic aortic valves is technically feasible. The proper position of the stented valve minimizes the risk for post-procedure paravalvular insufficiency and provides good transaortic pressure gradient. © 2016 Wiley Periodicals, Inc.

Transcatheter Pulmonary Valve Replacement in a Carcinoid Heart.

Carcinoid heart disease presents as right-sided heart failure attributable to the dysfunction of the tricuspid and pulmonary valves. Although surgical valve replacement is the mainstay of treatment when patients become symptomatic, it is associated with substantial perioperative mortality rates. We present a case of severe pulmonary valve stenosis secondary to carcinoid heart disease, treated successfully with percutaneous valve replacement. A 67-year-old man with severe pulmonary valve stenosis was referred to our center for pulmonary valve replacement. The patient had a history of metastatic neuroendocrine tumor of the small bowel with carcinoid syndrome, carcinoid heart disease, and tricuspid valve regurgitation previously treated with surgical valve replacement. Because of the patient's severe chronic obstructive pulmonary disease and hostile chest anatomy seen on a computed tomographic scan dating from previous cardiothoracic surgery, we considered off-label percutaneous valve replacement a viable alternative to open-heart surgery. A 29-mm Edwards Sapien XT valve was successfully deployed over the native pulmonary valve. There were no adverse sequelae after the procedure, and the patient was discharged from the hospital the next day. This case report shows that percutaneous valve replacement can be a valid option in carcinoid heart disease patients who are not amenable to surgical valve replacement.

Transcatheter aortic valve implantation despite challenging vascular access.

We describe transcatheter aortic valve implantation in a patient who had severe peripheral artery disease. The patient's vascular condition required additional preliminary peripheral intervention to enable adequate vascular access. A 78-year-old man with severe aortic stenosis, substantial comorbidities, and severe heart failure symptoms was referred for aortic valve replacement. The patient's 20-mm aortic annulus necessitated the use of a 23-mm Edwards Sapien valve inserted through a 22F sheath, which itself needed a vessel diameter of at least 7 mm for percutaneous delivery. The left common femoral artery was selected for valve delivery. The left iliac artery and infrarenal aorta underwent extensive intervention to achieve an intraluminal diameter larger than 7 mm. After aortic valvuloplasty, valve deployment was successful, and the transaortic gradient decreased from 40 mmHg to less than 5 mmHg. The patient was discharged from the hospital 4 days postoperatively. We conclude that transcatheter aortic valve implantation can be successfully performed in patients with obstructed vascular access, including stenosis of the infrarenal aorta and the subclavian and coronary arteries.

Concomitant transapical mitral valvuloplasty and CentriMag assist device placement: in a "no-option" patient.

Left ventricular assist devices and percutaneous valve interventions have radically changed the treatment of advanced heart disease and minimized surgical morbidity in patients with end-stage heart failure who would not survive conventional surgery. We describe a successful approach to the simultaneous placement of a percutaneous left ventricular assist device and mitral valvuloplasty in a decompensated patient with end-stage ischemic cardiomyopathy, severe peripheral arterial disease, porcelain aorta, and severe mitral and aortic disease.

Aortic valve regurgitation that resolved after a ruptured coronary sinus aneurysm was patched.

Sinus of Valsalva aneurysms appear to be rare. They occur most frequently in the right sinus of Valsalva (52%) and the noncoronary sinus (33%). More of these aneurysms originate from the right coronary cusp than from the noncoronary cusp. Surgical intervention is usually recommended when symptoms become evident. We report the case of a 34-year-old woman who presented with a congenital, ruptured sinus of Valsalva aneurysm that originated from the noncoronary cusp. Moderate aortic regurgitation was associated with this lesion. Simple, direct patch closure of the ruptured aneurysm resolved the patient's left-to-right shunt and was associated with decreased aortic regurgitation to a degree that valve replacement was not necessary. Only trace residual aortic regurgitation was evident after 3 months, and the patient remained free of symptoms after 6 months. Our observations support the idea that substantial runoff blood flow in the immediate supra-annular region can be responsible for aortic regurgitation in the absence of a notable structural defect in the aortic valve, and that restoring physiologic flow in this region and equalizing aortic-cusp closure pressure can largely or completely resolve aortic insufficiency. Accordingly, valve replacement may not be necessary in all cases of ruptured sinus of Valsalva aneurysms with associated aortic valve regurgitation.

Superior vena cava thrombosis and paradoxical embolic stroke due to collateral drainage from the brachiocephalic vein to the left atrium.

Thrombosis involving a permanent infusion catheter in the subclavian vein and superior vena cava is relatively common, especially in cancer patients. Edema of the arms and head is a well-known clinical consequence of this thrombosis, with an intrinsic risk of pulmonary embolism; however, systemic embolization into the cerebral circulation has not been reported as a sequela. Herein, we describe the case of a 56-year-old man with metastatic prostate cancer who developed superior vena cava syndrome due to extensive thrombosis in the presence of a central venous catheter that was used for long-term chemotherapy. The patient's case was complicated by a cerebrovascular accident that was most likely caused by a paradoxical air embolism. A clear mechanism for the embolism was provided by a network of collateral veins, which developed between the brachiocephalic vein and the left atrium due to the superior vena cava obstruction and resulted in a right-to-left shunt. We discuss diagnosis and treatment of the condition in our patient and in general terms.

Human cardiac stem cells.

The identification of cardiac progenitor cells in mammals raises the possibility that the human heart contains a population of stem cells capable of generating cardiomyocytes and coronary vessels. The characterization of human cardiac stem cells (hCSCs) would have important clinical implications for the management of the failing heart. We have established the conditions for the isolation and expansion of c-kit-positive hCSCs from small samples of myocardium. Additionally, we have tested whether these cells have the ability to form functionally competent human myocardium after infarction in immunocompromised animals. Here, we report the identification in vitro of a class of human c-kit-positive cardiac cells that possess the fundamental properties of stem cells: they are self-renewing, clonogenic, and multipotent. hCSCs differentiate predominantly into cardiomyocytes and, to a lesser extent, into smooth muscle cells and endothelial cells. When locally injected in the infarcted myocardium of immunodeficient mice and immunosuppressed rats, hCSCs generate a chimeric heart, which contains human myocardium composed of myocytes, coronary resistance arterioles, and capillaries. The human myocardium is structurally and functionally integrated with the rodent myocardium and contributes to the performance of the infarcted heart. Differentiated human cardiac cells possess only one set of human sex chromosomes excluding cell fusion. The lack of cell fusion was confirmed by the Cre-lox strategy. Thus, hCSCs can be isolated and expanded in vitro for subsequent autologous regeneration of dead myocardium in patients affected by heart failure of ischemic and nonischemic origin.

Acute thrombocytopenia after liver transplant: role of platelet activation, thrombopoietin deficiency and response to high dose intravenous IgG treatment.

BACKGROUND/AIMS: Thrombocytopenia is common after liver transplantation due to platelet sequestration secondary to hypersplenism. The aim of this study was to further investigate the causes of this condition, as well as the response of thrombocytopenia to high dose intravenous immunoglobulins. METHODS: We retrospectively studied 73 patients who underwent liver transplantation. Out of these 73 patients, 27 had severe thrombocytopenia and were treated with high dose intravenous immunoglobulin. Additionally, we retrospectively studied 8 patients undergoing liver transplantation. RESULTS: Our data suggest that splenomegaly is not the only factor responsible for thrombocytopenia after liver transplantion and two additional phenomena, namely, reduced platelet production due to reduced thrombopoietin levels and sustained platelets activation take part in the pathogenesis of this condition. The infusion of high dose immunoglobulins induced a safe, prompt, complete and persistent resolution of severe thrombocytopenia in more than 70% of patients. CONCLUSIONS: Based on these findings, treatment with high dose intravenous immunoglobulins should be considered in the management of severe thrombocytopenia after liver transplant, although additional randomized trials are warranted.

Cardiac stem cells possess growth factor-receptor systems that after activation regenerate the infarcted myocardium, improving ventricular function and long-term survival.

Cardiac stem cells and early committed cells (CSCs-ECCs) express c-Met and insulin-like growth factor-1 (IGF-1) receptors and synthesize and secrete the corresponding ligands, hepatocyte growth factor (HGF) and IGF-1. HGF mobilizes CSCs-ECCs and IGF-1 promotes their survival and proliferation. Therefore, HGF and IGF-1 were injected in the hearts of infarcted mice to favor, respectively, the translocation of CSCs-ECCs from the surrounding myocardium to the dead tissue and the viability and growth of these cells within the damaged area. To facilitate migration and homing of CSCs-ECCs to the infarct, a growth factor gradient was introduced between the site of storage of primitive cells in the atria and the region bordering the infarct. The newly-formed myocardium contained arterioles, capillaries, and functionally competent myocytes that with time increased in size, improving ventricular performance at healing and long thereafter. The volume of regenerated myocytes was 2200 microm3 at 16 days after treatment and reached 5100 microm3 at 4 months. In this interval, nearly 20% of myocytes reached the adult phenotype, varying in size from 10,000 to 20,000 microm3. Moreover, there were 43+/-13 arterioles and 155+/-48 capillaries/mm2 myocardium at 16 days, and 31+/-6 arterioles and 390+/-56 capillaries at 4 months. Myocardial regeneration induced increased survival and rescued animals with infarcts that were up to 86% of the ventricle, which are commonly fatal. In conclusion, the heart has an endogenous reserve of CSCs-ECCs that can be activated to reconstitute dead myocardium and recover cardiac function.

Stem cells in the dog heart are self-renewing, clonogenic, and multipotent and regenerate infarcted myocardium, improving cardiac function.

The purpose of this study was to determine whether the heart in large mammals contains cardiac progenitor cells that regulate organ homeostasis and regenerate dead myocardium after infarction. We report that the dog heart possesses a cardiac stem cell pool characterized by undifferentiated cells that are self-renewing, clonogenic, and multipotent. These clonogenic cells and early committed progeny possess a hepatocyte growth factor (HGF)-c-Met and an insulin-like growth factor 1 (IGF-1)-IGF-1 receptor system that can be activated to induce their migration, proliferation, and survival. Therefore, myocardial infarction was induced in chronically instrumented dogs implanted with sonomicrometric crystals in the region of the left ventricular wall supplied by the occluded left anterior descending coronary artery. After infarction, HGF and IGF-1 were injected intramyocardially to stimulate resident cardiac progenitor cells. This intervention led to the formation of myocytes and coronary vessels within the infarct. Newly generated myocytes expressed nuclear and cytoplasmic proteins specific of cardiomyocytes: MEF2C was detected in the nucleus, whereas alpha-sarcomeric actin, cardiac myosin heavy chain, troponin I, and alpha-actinin were identified in the cytoplasm. Connexin 43 and N-cadherin were also present. Myocardial reconstitution resulted in a marked recovery of contractile performance of the infarcted heart. In conclusion, the activation of resident primitive cells in the damaged dog heart can promote a significant restoration of dead tissue, which is paralleled by a progressive improvement in cardiac function. These results suggest that strategies capable of activating the growth reserve of the myocardium may be important in cardiac repair after ischemic injury.

Bone marrow cells differentiate in cardiac cell lineages after infarction independently of cell fusion.

Recent studies in mice have challenged the ability of bone marrow cells (BMCs) to differentiate into myocytes and coronary vessels. The claim has also been made that BMCs acquire a cell phenotype different from the blood lineages only by fusing with resident cells. Technical problems exist in the induction of myocardial infarction and the successful injection of BMCs in the mouse heart. Similarly, the accurate analysis of the cell populations implicated in the regeneration of the dead tissue is complex and these factors together may account for the negative findings. In this study, we have implemented a simple protocol that can easily be reproduced and have reevaluated whether injection of BMCs restores the infarcted myocardium in mice and whether cell fusion is involved in tissue reconstitution. For this purpose, c-kit-positive BMCs were obtained from male transgenic mice expressing enhanced green fluorescence protein (EGFP). EGFP and the Y-chromosome were used as markers of the progeny of the transplanted cells in the recipient heart. By this approach, we have demonstrated that BMCs, when properly administrated in the infarcted heart, efficiently differentiate into myocytes and coronary vessels with no detectable differentiation into hemopoietic lineages. However, BMCs have no apparent paracrine effect on the growth behavior of the surviving myocardium. Within the infarct, in 10 days, nearly 4.5 million biochemically and morphologically differentiated myocytes together with coronary arterioles and capillary structures were generated independently of cell fusion. In conclusion, BMCs adopt the cardiac cell lineages and have an important therapeutic impact on ischemic heart failure.

Autologous peripheral blood stem cell transplantation for myocardial regeneration: a novel strategy for cell collection and surgical injection.

PURPOSE: Bone-marrow and peripheral blood-derived stem cells can be used as stimulators of myogenesis and angiogenesis. We describe an original technique for collection and surgical intramyocardial injection of peripheral blood-derived stem cells. DESCRIPTION: Stem cells are mobilized from the bone marrow by means of subcutaneous administration of Lenogastrim (Granocyte 34 [Aventis Pharma, Milan, Italy]) for 4 days. Then the day before the operation the peripheral blood-derived stem cells are collected by means of apheresis and processed in order to obtain the CD 133+ cells. Cells are injected into the myocardium in a beating heart in order to induce angiogenesis locally or myogenesis, or both. When necessary, off-pump coronary artery bypass grafting is previously accomplished. EVALUATION: Thus far we have investigated 4 patients (3 patients who have received off-pump peripheral blood stem cell injection and coronary bypass grafting through median sternotomies, and 1 patient who underwent cell transplant alone through a minimally-invasive transdiaphragmatic approach). No complications were noted at a mean of 4 months after surgery. CONCLUSIONS: This novel method of peripheral bone marrow stem cell collection and intramyocardial injection seems to be safe, feasible, and reproducible. However, there is need of further evidence to definitely assess safety issues and clinical results.