Pulmonary Bed Research Articles

Clinical-Physiological Considerations in Patients Undergoing Staged Palliation for a Functionally Single Ventricle.

The objectives of this review are to discuss the pathophysiology of the circulation with a functionally univentricular heart, with a focus on the unique physiologic characteristics, which provide the underpinnings for the management of these complex patients. MEDLINE and PubMed. The circulation of the patient with a functionally univentricular heart displays unique physiologic characteristics, which are quite different from those of the normal biventricular circulation. There are profound differences within the heart itself in terms of ventricular function, interventricular interactions, and myocardial architecture, which are likely to have significant implications for the efficiency of ventricular ejection and metabolism. The coupling between the systemic ventricle and the aorta also displays unique features. The 3D orientation of the Fontan anastomosis itself can profoundly impact cardiac output, although the "portal" pulmonary arterial bed is a crucial determinant of overall cardiovascular function. As a result, disease-specific approaches to improve cardiovascular function are required at all stages during the care of these complex patients.

Hyaluronic Acid Molecular Weight Determines Lung Clearance and Biodistribution after Instillation

Hyaluronic acid (HA) has emerged as a versatile polymer for drug delivery. Multiple commercial products utilize HA, it can be obtained in a variety of molecular weights, and it offers chemical handles for cross-linkers, drugs, or imaging agents. Previous studies have investigated multiple administration routes, but the absorption, biodistribution, and pharmacokinetics of HA after delivery to the lung is relatively unknown. Here, pharmacokinetic parameters were investigated by delivering different molecular weights of HA (between 7 and 741 kDa) to the lungs of mice. HA was labeled with either a near-infrared dye or with iodine-125 conjugated to HA using a tyrosine linker. In initial studies, dye-labeled HA was instilled into the lungs and fluorescent images of organs were collected at 1, 8, and 24 h post administration. Data suggested longer lung persistence of higher molecular weight HA, but signal diminished for all molecular weights at 8 h. To better quantitate pharmacokinetic parameters, different molecular weights of iodine-125 labeled HA were instilled and organ radioactivity was determined after 1, 2, 4, 6, and 8 h. The data showed that, after instillation, the lungs contained the highest levels of HA, as expected, followed by the gastrointestinal tract. Smaller molecular weights of HA showed more rapid systemic distribution, while 67 and 215 kDa HA showed longer persistence in the lungs. Lung exposure appeared to be optimum in this size range due to the rapid absorption of <67 kDa HA and the poor lung penetration and mucociliary clearance of viscous solutions of HA > 215 kDa. The versatility of HA molecular weight and conjugation chemistries may, therefore, provide new opportunities to extend pulmonary drug exposure and potentially facilitate access to lymph nodes draining the pulmonary bed.

Expression and role of connexin-based gap junctions in pulmonary inflammatory diseases.

Connexins are transmembrane proteins that can generate intercellular communication channels known as gap junctions. They contribute to the direct movement of ions and larger cytoplasmic solutes between various cell types. In the lung, connexins participate in a variety of physiological functions, such as tissue homeostasis and host defence. In addition, emerging evidence supports a role for connexins in various pulmonary inflammatory diseases, such as asthma, pulmonary hypertension, acute lung injury, lung fibrosis or cystic fibrosis. In these diseases, the altered expression of connexins leads to disruption of normal intercellular communication pathways, thus contributing to various pathophysiological aspects, such as inflammation or tissue altered reactivity and remodeling. The present review describes connexin structure and organization in gap junctions. It focuses on connexins in the lung, including pulmonary bronchial and arterial beds, by looking at their expression, regulation and physiological functions. This work also addresses the issue of connexin expression alteration in various pulmonary inflammatory diseases and describes how targeting connexin-based gap junctions with pharmacological tools, synthetic blocking peptides or genetic approaches, may open new therapeutic perspectives in the treatment of these diseases.

Antagonism of stem cell factor/c-kit signaling attenuates neonatal chronic hypoxia-induced pulmonary vascular remodeling.

BackgroundAccumulating evidence suggests that c-kit positive cells are present in the remodeled pulmonary vasculature bed of patients with pulmonary hypertension (PH). Whether stem cell factor (SCF)/ c-kit regulated pathways potentiate pulmonary vascular remodeling is unknown. Here, we tested the hypothesis that attenuated c-kit signaling would decrease chronic hypoxia-induced pulmonary vascular remodeling by decreasing pulmonary vascular cell mitogenesis.MethodsNeonatal FVB/NJ mice treated with non-immune IgG (PL), or c-kit neutralizing antibody (ACK2) as well as c-kit mutant mice (WBB6F1- Kit W− v/ +) and their congenic controls, were exposed to normoxia (FiO2=0.21) or hypoxia (FiO2=0.12) for two weeks. Following this exposure, right ventricular systolic pressure (RVSP), right ventricular hypertrophy (RVH), pulmonary vascular cell proliferation and remodeling were evaluated.ResultsAs compared to chronically hypoxic controls, c-kit mutant mice had decreased RVSP, RVH, pulmonary vascular remodeling and proliferation. Consistent with these findings, administration of ACK2 to neonatal mice with chronic hypoxia-induced PH decreased RVSP, RVH, pulmonary vascular cell proliferation and remodeling. This attenuation in PH was accompanied by decreased extracellular signal-regulated protein kinase (ERK) 1/2 activation.ConclusionSCF/c-kit signaling may potentiate chronic hypoxia-induced vascular remodeling by modulating ERK activation. Inhibition of c-kit activity may be a potential strategy to alleviate PH.

Abstract 19002: Predictive Value of the Intraoperative Pulmonary Artery Flow Study for Early and Late Outcome After Surgical Treatment of Pulmonary Atresia With Ventricular Septal Defect and Major Aortopulmonary Collateral Arteries (MAPCAs)

Introduction &amp; Hypothesis: 1. To evaluate the accuracy of the intraoperative pulmonary artery (PA) flow study in determining the feasibility of concomitant VSD closure after complete one-stage unifocalization in patients with pulmonary atresia with VSD and MAPCAs. 2. To determine the ability of the PA flow study to predict long-term outcomes. Methods: Between October 1996 and May 2015, a PA flow study was obtained in 92 patients undergoing complete one-stage unifocalization. The study was performed by cannulating the unifocalized central PA. With the heart beating, incremental volumes of blood were pumped through the PAs. The ability to achieve 100% flow (2.5 l/min/m 2 ) into the pulmonary bed at a mean pressure (mPAP) ≤ 30 mmHg was used as an indicator for acceptability of VSD closure. Results: Among the 92 patients who had a PA flow study, 23 had a mPAP &gt; 30 mmHg and the VSD was left open. VSD closure was performed in 69 patients (mPAP 24 ± 5 mmHg, range 11-34 mmHg). However, four (5.8%) required patch fenestration due to suprasystemic RV pressure. The recorded mPAPs of these 4 patients were 29, 24, 22 and 28 mmHg, respectively. In the whole cohort, median weight at operation was 7.9 kg (range, 2.5-54 kg). The PA flow study accurately predicted successful VSD closure (area under the curve 0.852, Figure 1A). VSD closure at the time of unifocalization resulted in a clear survival advantage (p = 0.0363). mPAP correlated with RVP to LVP ratio (rho 0.460, p = 0.0001) and better long-term results were observed with intraoperative mPAP ≤ 30 mmHg (p = 0.24, Figure 1B). Conclusions: Successful VSD closure in patients with MAPCAs can be reliably defined by an intraoperative PA flow study with a cut-off of 30 mmHg. The PA flow study predictive value is particularly useful to select patients in which the VSD should be left open. mPAP strongly correlates with the intraoperative RVP/LVP ratio and lower values of mPAP at the time of the unifocalization are associated with improved long-term outcomes.

Double Inlet Single Ventricle With Transposition of the Great Arteries and Situs Inversus With Dextrocardia in an Adult Without Surgical Correction: Challenges and Triumphs

SESSION TITLE: Cardiovascular Disease Case Report Posters SESSION TYPE: Affiliate Case Report Poster PRESENTED ON: Tuesday, October 27, 2015 at 01:30 PM - 02:30 PM INTRODUCTION: Single ventricle abnormality represents approximately 1% of all congenital cardiac defects, with an incidence of 0.05-0.1:10'000 live births [1]. With current medical and surgical advances, more patients are surviving to adulthood. Acute decompensation in adults is a common cause of death. New corrective approaches should be entertained to support the failing single ventricular hearts [2, 3] CASE PRESENTATION: We present a case of a 61 year old female with unrepaired cyanotic congenital heart disease. Her defect is significant for double inlet single ventricle with left looping and transposition of great arteries and situs inversus with dextrocardia, with somewhat “protected” pulmonary bed secondary to pulmonary stenosis (PS). The patient has done well, despite developing atrial fibrillation and worsening atrioventricular valve regurgitation and complete heart block. TEE confirmed well preserved systolic function with EF 54%, severe PS and severe biatrial enlargement. Right and Left catheterization notable for within normal limits coronary flow and high normal pulmonary artery pressures. Cardiopulmonary testing is significant for abnormal cardiovascular response - inability to augment stroke volume and increased oxygen consumption with submaximal exercise response. Multidisciplinary decision was made to proceed with epicardial pacemaker (EPM). After uneventful minimal inferior medial sternotomy approach for placement and uncomplicated CTICU recovery our patient is undergoing evaluation for orthotopic heart transplant DISCUSSION: The goal of EPM placement was to improve the patient's choronotropic incompetence and respectively functional capacity. After initial post-operative recovery, patient noted improved functional status and oxygen saturation in high to low 70s CONCLUSIONS: The uncorrected complex adult cyanotic cardiac pathology offers multifactorial array of challenges to the treating team. Understanding of the anatomy and pathological complications, as well as the physiological adaptation of each patient's condition, is essential for the optimum management of these intricate disorders Reference #1: EK Steinberger, C Ferencz, CA Loffredo. Infants With Single Ventricle:A Population-Based Epidemiological Study. Teratology.2002;65:103-115 Reference #2: Rossano JW, Chang AC.Perioperative management of patients with poorly functioning ventricles in the setting of the functionally univentricular heart. Cardiol Young.2006;16 (S1):47-54 Reference #3: H Vyas, DJ Hagler. Double Inlet Left Ventricle. Cur Treat Opt Card Med.2007;9:391-398 DISCLOSURE: The following authors have nothing to disclose: Ntesi Asimi, Jane Wilcox, Sherif Afifi No Product/Research Disclosure Information

CLOSING OF INTERVENTRICULAR SEPTUM DEFECT IN ONE-STEP AND STEPWISE SURGICAL TREATMENT IN PATIENTS WITH PULMONARY ATRESIA AND AORTO-PULMONARY COLLATERALS

Pulmonary atresia with defect of interventricular septum and collateral pulmonary blood flow refers to complicated congenital malformation of the heart. Surgical treatment represents itself as very difficult task because of anatomical variability of this abnormality. The main problem of surgery is a definitive repair of the defect including correction of maldistributions of pulmonary arterial bed (unifocalization of pulmonary blood flow), reconstruction of outflow tract of the right ventricle and closing of interventricular septum defect. The performance of closing interventricular septum defect could be successful in patients with pulmonary atresia and collateral pulmonary blood flow in case of stepwise and one-step surgical treatment. The combination of maximal number of pulmonary segments and sufficient development of central pulmonary arteries facilitates to progress of assigned task. Patients with the level of pulmonary-arterial index more than 170 mm/m2 and integrity of pulmonary arterial bed, centralization of pulmonary segments (minimum 15) could be considered as a candidate for definite repair of the defect.

Vasopressin decreases pulmonary-to-systemic vascular resistance ratio in a porcine model of severe hemorrhagic shock.

Vasopressors are gaining renewed interest as treatment adjuncts in hemorrhagic shock. The ideal vasoconstrictor will increase systemic blood pressure without increasing pulmonary vascular resistance (PVR), which hinders pulmonary perfusion and exacerbates hypoxemia. However, the selectivity of pressors for pulmonary versus systemic vasoconstriction during hemorrhage has not been characterized. The purpose of this study was to test the hypothesis that vasopressin (VP) has distinct effects on pulmonary versus systemic hemodynamics, unlike the catecholamine vasopressors norepinephrine (NE) and phenylephrine (PE). Anesthetized and ventilated pigs were assigned to resuscitation with saline only (n = 7) or saline with VP (n = 6), NE (n = 6), or PE (n = 6). Animals were hemorrhaged to a target volume of 30 mL/kg and a mean arterial pressure of 35 mmHg. One hour after the start of hemorrhage, animals were resuscitated with saline up to one shed blood volume, followed by either additional saline or a vasopressor. Hemodynamics and oxygenation were measured hourly for 4 h after the start of hemorrhage. Vasopressin increased systemic vascular resistance (SVR) while sparing the pulmonary vasculature, leading to a 45% decrease in the PVR/SVR ratio compared with treatment with PE. Conversely, NE induced pulmonary hypertension and led to an increased PVR/SVR ratio associated with decreased oxygen saturation. Phenylephrine and crystalloid had no significant effect on the PVR/SVR ratio. Sparing of pulmonary vasoconstriction occurs only with VP, not with administration of crystalloid or catecholamine pressors. The ability of VP to maintain blood oxygenation indicates that VP may prevent hypoxemia in the management of hemorrhagic shock.

Assessment of systemic and pulmonary arterial remodelling in women with systemic sclerosis

Objectives: Systemic sclerosis (SSc) leads to pulmonary circulation dysfunctionand there are some indications of systemic circulation impairment. We evaluated the influence of SSc on the elastic properties of large systemic arterial walls and potential correlations between systemic and pulmonary circulation involvement.Method: We examined 75 consecutive women (mean age 53.13 ± 10.1 years) with confirmed SSc [mean disease duration (DD) 7.1 ± 9.1 years] and 21 age-matched female volunteers (mean age 52.6 ± 8.3 years, ns). Pulse wave velocity (PWV) and transthoracic echocardiography were performed. SSc patients were divided into two groups according to the median of DD: ≤ 3 years (39 patients) and > 3 years (36 patients).Results: Patients with DD > 3 years had higher PWV than those with DD ≤ 3 years and controls (log PWV: 2.23 ± 0.23 vs. 2.13 ± 0.16 and vs. 2.11 ± 0.16 m/s; p = 0.028 and 0.029, respectively). In addition, echocardiographic indices showed impaired right ventricular (RV) function in the patients with DD > 3 years. Also in these SSc patients, PWV correlated with clinical and echocardiographic parameters of pulmonary circulation: age (r = 0.64, p < 0.0001), acceleration time of pulmonary ejection (AcT; r = −0.38, p = 0.021), and tricuspid regurgitation peak gradient (TRPG; r = 0.34, p = 0.04). Multiple linear regression analysis showed that PWV was independently associated with DD (β = 0.22, p = = 0.02), AcT (β = −0.215, p = 0.03), and age (β = 0.44, p < 0.001).Conclusions: In patients with SSc lasting more than 3 years, the disease is characterized by increased stiffness of the large systemic arteries. Longer duration of SSc leads simultaneously to the increased stiffness of the large systemic arteries and to the progressive impairment of RV function and its coupling to the pulmonary arterial bed.

Management of severe pulmonary hypertension in patients undergoing mitral valve surgery.

Pulmonary hypertension (PH) is simply defined as a mean pulmonary artery pressure greater than 25mmHg at rest; however, may result from varying combinations of abnormal pulmonary artery (PA) blood flow, pulmonary vascular resistance (PVR), PA compliance, and pulmonary venous pressure. Mitral regurgitation (MR) allows for partial transmission of systemic arterial pressure into the pulmonary venous system. Mitral stenosis (MS) prevents pulmonary venous drainage into the left ventricle. In either case, the direct result is marked pressurization of the pulmonary venous system, with the primary cause of PH in significant mitral valve disease (PHMVD) being pulmonary venous hypertension (PVH). Chronic and severe PVH may then lead to muscularization of the pulmonary arterial bed, with a rise in PVR and loss of pulmonary arterial compliance that follows ("reactive" pulmonary vascular disease). Right heart dysfunction ensues once the PVR rises and the compliance falls to a point in which the right ventricle (RV) cannot overcome the increased afterload. However, it is worth emphasizing that in the setting of PHMVD, no matter the degree of mismatch between RV afterload and RV function, the root condition in the patient and cause of the PH remains severe MV disease. Without correction of the primary condition, the patient's heart failure (HF), PH, PVR, and RV dysfunction will remain or progress. Moreover, direct PH medical therapies are ineffective and may actually worsen left heart congestion in the setting of unremediated MVD. Therefore, although surgery may be a higher risk in some patients with PHMVD, the potential benefits justify the risks in the majority of cases. If needed, direct medical management of PH is far simpler and more effective once the MVD is corrected, given the degree of left heart congestion often improves dramatically. Therefore, corrective mitral valve intervention should be considered as the main and definitive treatment for these patients.

Murine study of portal hypertension associated endothelin-1 hypo-response.

To investigate endothelin-1 hypo-responsive associated with portal hypertension in order to improve patient treatment outcomes. Wild type, eNOS(-/-) and iNOS(-/-) mice received partial portal vein ligation surgery to induce portal hypertension or sham surgery. Development of portal hypertension was determined by measuring the splenic pulp pressure, abdominal aortic flow and portal systemic shunting. To measure splenic pulp pressure, a microtip pressure transducer was inserted into the spleen pulp. Abdominal aortic flow was measured by placing an ultrasonic Doppler flow probe around the abdominal aorta between the diaphragm and celiac artery. Portal systemic shunting was calculated by injection of fluorescent microspheres in to the splenic vein and determining the percentage accumulation of spheres in liver and pulmonary beds. Endothelin-1 hypo-response was evaluated by measuring the change in abdominal aortic flow in response to endothelin-1 intravenous administration. In addition, thoracic aorta endothelin-1 contraction was measured in 5 mm isolated thoracic aorta rings ex-vivo using an ADI small vessel myograph. In wild type and iNOS(-/-) mice splenic pulp pressure increased from 7.5 ± 1.1 mmHg and 7.2 ± 1 mmHg to 25.4 ± 3.1 mmHg and 22 ± 4 mmHg respectively. In eNOS(-/-) mice splenic pulp pressure was increased after 1 d (P = NS), after which it decreased and by 7 d was not significantly elevated when compared to 7 d sham operated controls (6.9 ± 0.6 mmHg and 7.3 ± 0.8 mmHg respectively, P = 0.3). Abdominal aortic flow was increased by 80% and 73% in 7 d portal vein ligated wild type and iNOS when compared to shams, whereas there was no significant difference in 7 d portal vein ligated eNOS(-/-) mice when compared to shams. Endothelin-1 induced a rapid reduction in abdominal aortic blood flow in wild type, eNOS(-/-) and iNOS(-/-) sham mice (50% ± 8%, 73% ± 9% and 47% ± 9% respectively). Following portal vein ligation endothelin-1 reduction in blood flow was significantly diminished in each mouse group. Abdominal aortic flow was reduced by 19% ± 9%, 32% ± 10% and 9% ± 9% in wild type, eNOS(-/-) and iNOS(-/-) mice respectively. Aberrant endothelin-1 response in murine portal hypertension is NOS isoform independent. Moreover, portal hypertension in the portal vein ligation model is independent of ET-1 function.

Pulmonary Arterial Hypertension Associated With Tetralogy of Fallot

Pulmonary arterial hypertension (PAH) is a common postoperative complication in patients with congenital heart disease (CHD). Although the recent clinical classification of pulmonary hypertension divided PAH associated with CHD (PAH-CHD) into several subclasses, the anatomical and hemodynamic features of postoperative PAH-CHD vary enormously. Therefore, it is still difficult to obtain clinical evidence supporting the indication of pulmonary vasodilators for PAH-CHD. We often encounter patients with PAH occurring after surgical treatment of tetralogy of Fallot (TOF), especially patients with major aortopulmonary collateral arteries (MAPCAs). PAH might be caused by pulmonary agenesis, hypoplasia and/or thrombosis, inadequate closure of the ventricular septal defect, relief of the pulmonic stenosis, or an excessively large prior systemic-to-pulmonary shunt. Moreover, patients with TOF and MAPCAs who are diagnosed as inoperable because of the presence of PAH show similar hemodynamic and clinical features to patients with Eisenmenger syndrome. The MAPCAs in these patients usually show hypoplastic and abnormal arborization. Based on our experience, we believe that PAH-targeted therapies are effective in some patients with PAH occurring after surgical treatment of TOF and MAPCAs, especially as an adjunct to percutaneous pulmonary angioplasty. To help classify patients with PAH associated with TOF, especially with MAPCAs, we propose several new subclassifications: "PAH due to hypoplastic pulmonary arterial beds", "PAH due to abnormal pulmonary arborization", or "segmental PAH associated with CHD." A multicenter registry of patients using a unified protocol is essential to explore the indications and efficacy of pulmonary vasodilators for postoperative PAH-CHD.

Balloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension.

ENWEndNote BIBJabRef, Mendeley RISPapers, Reference Manager, RefWorks, Zotero AMA Kurzyna M, Darocha S, Koteja A, Pietura R, Torbicki A. EditorialBalloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension. Advances in Interventional Cardiology/Postępy w Kardiologii Interwencyjnej. 2015;11(1):1-4. doi:10.5114/pwki.2015.49176. APA Kurzyna, M., Darocha, S., Koteja, A., Pietura, R., & Torbicki, A. (2015). EditorialBalloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension. Advances in Interventional Cardiology/Postępy w Kardiologii Interwencyjnej, 11(1), 1-4. https://doi.org/10.5114/pwki.2015.49176 Chicago Kurzyna, Marcin, Szymon Darocha, Andrzej Koteja, Radosław Pietura, and Adam Torbicki. 2015. "EditorialBalloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension". Advances in Interventional Cardiology/Postępy w Kardiologii Interwencyjnej 11 (1): 1-4. doi:10.5114/pwki.2015.49176. Harvard Kurzyna, M., Darocha, S., Koteja, A., Pietura, R., and Torbicki, A. (2015). EditorialBalloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension. Advances in Interventional Cardiology/Postępy w Kardiologii Interwencyjnej, 11(1), pp.1-4. https://doi.org/10.5114/pwki.2015.49176 MLA Kurzyna, Marcin et al. "EditorialBalloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension." Advances in Interventional Cardiology/Postępy w Kardiologii Interwencyjnej, vol. 11, no. 1, 2015, pp. 1-4. doi:10.5114/pwki.2015.49176. Vancouver Kurzyna M, Darocha S, Koteja A, Pietura R, Torbicki A. EditorialBalloon pulmonary angioplasty for chronic thromboembolic pulmonary hypertension. Advances in Interventional Cardiology/Postępy w Kardiologii Interwencyjnej. 2015;11(1):1-4. doi:10.5114/pwki.2015.49176.

Protein interactions of cortactin in relation to invadopodia formation in metastatic renal clear cell carcinoma.

In the present study, we wanted to examine the predominant factor/s in the initiation of metastasis. We used samples of advanced grades of renal clear cell carcinoma with documented clinical history of vena caval spread as the experimental group. The major rationale for this selection is the fact that renal cell carcinoma metastasize extensively through the inferior vena cava up to the pulmonary bed and often exist as a continuous mass of metastatic tissue. As cortactin plays a significant role in invadopodia formation during initiation of metastasis, in the present study, we tested expression of cortactin and phospho(tyr421)-cortactin in different grades of renal cell clear carcinoma and examined its property to bind to actin. The findings of the present study suggest that the variations of the local physiological milieu are the driving forces for metastasis by enhancing molecular mechanisms for lamellipodia formation. We conclude that localization of cortactin in cancer cells and interaction between actin and its nucleators are crucial for cancer progression.

Comparative Analysis of Infused “Static”, Ex Vivo-Generated Platelets Vs. Infused Megakaryocytes-Generated Platelets: A Cautionary Tale

Ex vivo-generated (EV) platelets beginning with embryonic stem cells or induced pluripotent stem cells (iPSCs) or hematopoietic progenitors cells (HPCs) may have clinical utility over donor-derived platelets, and efforts to produce such EV-platelets have been pursued in several laboratories under static megakaryocyte (Meg) culture conditions. Success in generating these has been reported, even demonstrating EV-platelet incorporation into growing thrombi in murine models. We have pursued an alternative strategy for thrombopoiesis using EV-Megs, grown from either human adult HPCs or from iPSCs or fetal livers, and directly infusing them into NOD-SCID gamma-interferon-deficient (NSG) mice. These studies were based on our prior observation that infused murine EV-Megs into wildtype mice are entrapped in the pulmonary bed and over the subsequent 1-4 hours release a wave of functional platelets at a significant level. We now show that infusion of human EV-Megs do the same in NSG mice, but resulting in two different pools of derived platelets: (1) A pool of young (as determined by thiazole orange staining) platelets having the same bell-shaped size distribution was seen as after infusion of human donor-derived platelets in these mice. These platelets take several hours to appear, but then have the same half-life as donor-derived platelets. These platelets are derived from the infused EV-Megs and were termed in vivo-generated (IV)-platelets. (2) A second pool of mostly older platelets was present that originated during the static growth of the EV-Megs, and these EV-platelets varied widely in size and age. Initially, these platelets accounted for a third of all the human platelets seen. Unlike IV-platelets, EV-platelets are immediately present and circulate with a markedly short half-life of 2-3 hours unless the recipient NSG mice were pre-treated with clodronate-ladened liposomes to delete their macrophage pools. Rapid removal of EV-platelets by macrophages is due to their being preactivated as determined by surface P-selectin expression in whole mice blood. These EV-platelets also had very limited further responsiveness to convulxin activation. On the other hand, human IV-platelets were quiescent prior to agonist stimulation in whole mice blood and responded strongly to agonist, similar to human donor-derived platelets infused into NSG mice. The IV-platelets were also selectively incorporated into cremaster arteriole laser injury thrombi over EV-platelets. Finally, directly harvested “platelets” from EV static-grown Megs were isolated and analyzed both in vitro and in vivo. Only a third of these particles are CD41+/CD42+ platelets and approximately half are actually CD41-/CD42-. Both pools showed the same wide size distribution in vitro and in vivo after infusion into mice. The CD41+/CD42+ fraction behaved just as the EV-platelets, but the CD41-/CD42- fraction half-life was unaffected by pre-treatment with clodronate-ladened liposomes. In summary, infused human Megs grown under static growth conditions released platelets in a recipient mouse’s lung with features characteristic of donor-derived platelets. On the other hand, “platelets” harvested from the same Megs were predominantly not even platelets as measured using CD41/CD42 markers. The portion that were CD41+/CD42+ platelets were preactivated, poorly responsive to agonists, and cleared rapidly. These findings set a standard on how to judge the potential clinical value of platelets derived from EV-Megs and also raise concerns whether direct visual imaging of “platelet release” in static culture is biologically meaningful given that most particles released were not CD41+/CD42+ platelets, and the ones that were CD41+/CD42+ were mis-sized and functionally limited. DisclosuresNo relevant conflicts of interest to declare.

Lung scintigraphy in the diagnosis of pulmonary embolism: pathophysiological and practical evidence

The protean clinical presentation of pulmonary embolism (PE) is the consequence of a complex series of haemodynamic and respiratory changes caused by the impact of thrombi within the pulmonary vasculature. Haemodynamic changes result from obstruction of the pulmonary arterial bed leading to increased pulmonary vascular resistances and they are manifested clinically as dyspnoea, engorgement of neck veins, and systemic arterial hypotension. Respiratory changes are characterised by lung volume reduction, hypocapnia and hypoxaemia. Reduced lung volume is mainly due to pulmonary consolidation, atelectasis and decreased distension of the thoracic cage due to chest pain. These pathophysiological changes affect both perfusion and ventilation and could explain the low sensitivity of the ventilation/perfusion (V/Q) mismatch scintigraphic approach in diagnosing PE. Acute PE causes redistribution of pulmonary blood flow from non-perfused areas and, to a lesser extent, of ventilation; this is a further factor arguing against the use of V/Q mismatch for the scintigraphic diagnosis of the disease. Hypoxaemia is primarily the consequence of V/Q abnormalities, namely the development of areas with a low V/Q ratio. On a Q scan this can easily be appreciated from hyperperfused lung areas that, by themselves, are a marker for the scintigraphic diagnosis of PE. In conclusion, a Q scan without a V scan, when properly interpreted according to the prospective investigative study of acute pulmonary embolism diagnosis methodology (presence or absence of wedge-shaped perfusion defects) and combined with the formulation of a pre-test clinical probability, can be used in most patients with clinical suspicion of PE, reducing costs and radiation load, increasing the practicality of the examination, and providing diagnostic accuracy comparable to that of CT angiography.

Pulmonary arteriovenous malformations: haemodynamics and shunt closure

The first description of pulmonary arteriovenous malformations (PAVM) was made already in 1897 by Churton [1]. PAVM are abnormal vascular structures that connect the pulmonary arterial bed directly to the pulmonary venous bed, thereby bypassing the pulmonary capillaries and resulting in an intrapulmonary shunt which, depending on number and size of the PAVM, may result in arterial desaturation and paradoxical systemic embolisation [2]. Because the PAVM are thin-walled vascular structures, they are prone to rupture, resulting in haemoptysis. A major step forward in the treatment of PAVM was the use of percutaneous transcatheter embolisation, using femoral venous access [3]. This procedure is safe and reduces the risk of paradoxical thromboembolisation and haemoptysis. Moreover, by reducing shunt flow, arterial oxygen saturation increases. Although percutaneous closure of PAVM has been performed for years, and a surprisingly small effect on pulmonary haemodynamics has been shown [4], the study by Vorselaars and co-workers in the present issue of the Netherlands Heart Journal [5] is the first to investigate the immediate consequences of PAVM closure on systemic haemodynamics. Using Finapres technology, which derives changes in stroke volume and systemic pressure from the pressure wave form as measured on a finger, they describe an overall decrease in stroke volume and cardiac output that corresponds in magnitude with the overall decrease in shunt fraction. This decrease in stroke volume is similar to the decrease in stroke volume, as measured directly by right heart catheterisation, observed in a case study at 4 months follow-up after PAVM [6]. It was speculated that such a decrease in stroke volume helped to explain the absence of an increase in pulmonary artery pressures [4], despite the fact that pulmonary vascular resistance should obviously increase as a consequence of the closure of the low resistance PAVM. The mechanism behind the observed decrease in stroke volume is unclear. It could be speculated that shunt closure and the accompanying increase in pulmonary vascular resistance result in a slight increase in right ventricular afterload, which limits right ventricular output. It is, however, more likely to assume that oxygen is regulated to fulfil the oxygen demand of peripheral tissues; shunt closure increases the oxygen content of arterial blood and hence for the same oxygen delivery, in the presence of improved oxygenation, less flow is required. The latter explanation is in accordance with the observation that the shunt fraction prior to embolisation (14 %) is similar in magnitude to the decrease in cardiac output (10 %) [5]. As pulmonary artery pressure increases during exercise, the driving pressure for the shunt flow increases, resulting in an increased shunt flow, which is accompanied by augmented arterial desaturation during exercise [7–9]. However, exercise capacity is surprisingly well-maintained in patients with PAVM, potentially due to the capability of the right heart to deal with volume overload. Indeed, although most patients report an increased exercise capacity and quality of life following shunt closure, an objective increase in exercise capacity is not found in all patients [10]. It is possible that changes in pulmonary and systemic haemodynamics upon shunt closure, which are relatively small under resting conditions, are exacerbated during exercise. Thus, while the study by Vorselaars in the present issue of the Netherlands Heart Journal provides an important observation in resting patients [5], a comprehensive evaluation of shunt flow, pulmonary and systemic haemodynamics and oxygen saturation during exercise prior to and following shunt closure would be of great benefit to enhance our understanding of the implications of shunt closure on exercise capacity.

Milrinone Relaxes Pulmonary Veins in Guinea Pigs and Humans

IntroductionThe phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH). However, its action on pulmonary veins (PVs) is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs) and humans.Material and MethodsPrecision-cut lung slices (PCLS) were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL).ResultsIn the IPL (GP), milrinone (10 µM) lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP), milrinone relaxed naïve and pre-constricted PVs (120%) and this relaxation was attenuated by inhibition of protein kinase G (KT 5823), adenyl cyclase (SQ 22536) and protein kinase A (KT 5720), but not by inhibition of NO-synthesis (L-NAME). In addition, milrinone-induced relaxation was dependent on the activation of KATP-, BKCa 2+- and Kv-channels. Human PVs also relaxed to milrinone (121%), however only if pre-constricted.DiscussionMilrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on KATP-, BKCa 2+- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease.

Metabolomics Reveals Metabolite Changes in Acute Pulmonary Embolism

Pulmonary embolism (PE) is a common cardiovascular emergency which can lead to pulmonary hypertension (PH) and right ventricular failure as a consequence of pulmonary arterial bed occlusion. The diagnosis of PE is challenging due to nonspecific clinical presentation, which results in relatively high mortality. Moreover, the pathological factors associated with PE are poorly understood. Metabolomics can provide new highlights which can help in the understanding of the processes and even propose biomarkers for its diagnosis. In order to obtain more information about PE and PH, acute PE was induced in large white pigs and plasma was obtained before and after induction of PE. Metabolic fingerprints from plasma were obtained with LC-QTOF-MS (positive and negative ionization) and GC-Q-MS. Data pretreatment and statistical analysis (uni- and multivariate) were performed in order to compare metabolic fingerprints and to select the metabolites that showed higher loading for the classification (28 from LC and 19 from GC). The metabolites found differentially distributed among groups are mainly related to energy imbalance in hypoxic conditions, such as glycolysis-derived metabolites, ketone bodies, and TCA cycle intermediates, as well as a group of lipidic mediators that could be involved in the transduction of the signals to the cells such as sphingolipids and lysophospholipids, among others. Results presented in this report reveal that combination of LC-MS- and GC-MS-based metabolomics could be a powerful tool for diagnosis and understanding pathophysiological processes due to acute PE.

Pulmonary Embolic Disorders

Deaths due to pulmonary thromboemboli are frequently encountered by the forensic pathologist and account for a significant percentage of sudden, unexpected deaths. Diagnosing these straightforward cases is often not a challenge, but unfortunately some cases in which a thromboembolism is expected can become complicated. Occasionally, a postmortem clot may mimic a thromboembolism and lead to a mistaken diagnosis, and in other situations it may become paramount to attempt to age a thrombus as part of a medicolegal lawsuit. Additionally, many individuals use the less specific term, “pulmonary emboli”, when referring to these cases in which a portion of a thrombus, usually originating in the deep veins of the lower extremities, breaks off and travels to the pulmonary vasculature bed where it occludes vessels and leads to a rapid demise. One must remember, though, that several other materials and tissues including fat, amniotic fluid, air, tumors, solid organs, synthetic materials, and parasites may be displaced and embolize to the lungs and cause significant disease. In the following pages we will provide a thorough review of pulmonary embolic disorders, focusing on those diseases most likely to be encountered by the forensic pathologist. The aim of this review is to aid the pathologist in using proper terminology, diagnosing various types of embolic disorders, and recognizing potential mimics.