Yuuki Mano

A novel method of measuring human lymphatic pumping using indocyanine green fluorescence lymphography.

OBJECTIVES Lymph transportation through the body is partly controlled by the intrinsic pumping of lymphatic vessels. Although an understanding of this process is important for medical application, little is currently known because it is difficult to measure. Here, we introduce an easy, safe, and cost-effective technique for measuring lymphatic pumping in leg superficial lymphatic vessels. Readings obtained with this technique were compared with values obtained with dynamic lymphoscintigraphy. Differences in lymphatic pumping between healthy volunteers and patients with lymphedema were also investigated. METHODS Indocyanine green (ICG) fluorescence lymphography was performed by subcutaneously injecting 0.3 mL of ICG (0.5%) into the dorsum of the foot. Real-time fluorescence images of lymph propulsion were obtained with an infrared-light camera system with the individual supine or sitting. A custom-made transparent sphygmomanometer cuff was wrapped around the lower leg and connected to a standard mercury sphygmomanometer. The cuff was inflated to 60 mm Hg and then gradually deflated at 5-minute intervals to lower the pressure by 10-mm Hg steps until the fluorescence contrast agent exceeded the upper border of the cuff, indicating that the lymphatic contraction had overcome the cuff pressure. Lymph pumping pressure (P(pump)) was defined as the value of the cuff pressure when the contrast agent exceeded the upper border of the cuff. We measured P(pump) among healthy volunteers who maintained a supine position and compared these values with measurements obtained from lymphoscintigraphy. P(pump) values while sitting were also compared between 30 legs from healthy volunteers and 30 legs from lymphedematous patients. RESULTS Among healthy, supine participants, P(pump) was 25.2 ± 16.7 mm Hg (mean ± standard deviation [SD]) when measured by ICG fluorescence lymphography. These values were significantly correlated with values taken using dynamic lymphoscintigraphy (r(2) = 0.54, p < .01), while 2 SDs of the mean were approximately 20 mm Hg, suggesting a substantial disagreement between the two methods (Bland-Altman plots). In the comparison of seated measurements, readings for healthy participants (P(pump) = 29.3 ± 16.0) were higher than those for lymphedematous participants (13.2 ± 14.9). CONCLUSION ICG fluorescence is an accurate-as well as a safe, easy, and economical-method of measuring lymphatic pumping. Therefore, it may develop as a vital tool for diagnosing lymphatic malfunctions even when they are only in their formative stages. Studies that use this technique may increase our knowledge of the lymphatic system as a whole, allowing us to develop better treatments for lymphatic disorders.

Imaging Mass Spectrometry Reveals Unique Lipid Distribution in Primary Varicose Veins

BACKGROUND The lipid metabolism of varicose veins (VVs) remains unknown. To elucidate the pathogenesis of VV, we utilized the novel technique of imaging mass spectrometry (IMS). MATERIALS AND METHODS We obtained VV tissues from 10 limbs of 10 VV patients who underwent great saphenous vein stripping. As control vein samples, we harvested segmental vein tissues from 6 limbs of 6 patients with peripheral artery occlusive disease who underwent infra-inguinal bypass with reversed saphenous vein grafting. To identify the localisation of lipid molecules in the VV tissues, we performed matrix-assisted laser desorption/ionization IMS (MALDI-IMS). We also performed MS/MS analyses to identify the structure of each molecule. RESULTS We obtained mass spectra directly from control vein tissues and VV tissues and found a unique localisation of lipid molecules in the VV tissues. We localised lysophosphatidylcholine (LPC) (1-acyl 16:0), phosphatidylcholine (PC) (1-acyl 36:4) and sphingomyelin (SM) (d18:1/16:0) at the site of the VV valve. CONCLUSION MALDI-IMS revealed the distribution of various lipid molecules in normal veins and VVs both. Accumulation of LPC (1-acyl 16:0), PC (1-acyl 36:4) and SM (d18:1/16:0) in the VV tissues suggested that inflammation associated with abnormal lipid metabolism may contribute to the development of VV.

Adventitial Vasa Vasorum Arteriosclerosis in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a common disease among elderly individuals. However, the precise pathophysiology of AAA remains unknown. In AAA, an intraluminal thrombus prevents luminal perfusion of oxygen, allowing only the adventitial vaso vasorum (VV) to deliver oxygen and nutrients to the aortic wall. In this study, we examined changes in the adventitial VV wall in AAA to clarify the histopathological mechanisms underlying AAA. We found marked intimal hyperplasia of the adventitial VV in the AAA sac; further, immunohistological studies revealed proliferation of smooth muscle cells, which caused luminal stenosis of the VV. We also found decreased HemeB signals in the aortic wall of the sac as compared with those in the aortic wall of the neck region in AAA. The stenosis of adventitial VV in the AAA sac and the malperfusion of the aortic wall observed in the present study are new aspects of AAA pathology that are expected to enhance our understanding of this disease.

Impaired lymphatic function recovered after great saphenous vein stripping in patients with varicose vein: Venodynamic and lymphodynamic results

OBJECTIVES Venodynamics and lymphodynamics may interact as an inseparable and mutually dependent dual outflow system. This study investigated the effect of surgical treatment on lower limb lymph flow in patients with varicose veins. METHODS Thirty-nine patients with varicose veins in the lower limb (28 patients with unilateral limb, 11 patients with bilateral limb), who demonstrated great saphenous vein reflux, were investigated with air-plethysmography and indocyanine green (ICG) fluorescence lymphography before surgical treatment and 6 months later. Fifteen healthy volunteers participated in this study as a control. With air-plethysmography, venous volume (VV) and venous filling time were measured. Venous filling index (VFI) was calculated. For ICG lymphography, 0.3 mL of ICG (0.5%) was subcutaneously injected at the dorsum of the foot. After the injection, fluorescent image of ICG dye was traced on real-time video images using a near-infrared camera system. The interval until the dye reached the knee was measured (transit time [TT]) in a standing position, which was previously demonstrated to correlate with the interval measured using dynamic isotope lymphoscintigraphy. RESULTS In CEAP clinical stage venous disease, TT in patients with C4 approximately 6 and C2 approximately 3 was significantly longer than that in the control group (587 +/- 97 seconds, 484 +/- 82 seconds, 252 +/- 29 seconds, respectively, mean +/- SD, P < .01). Among all limbs with varicose veins, there were correlations between TT and VV (Pearson r = 0.31, P < .01), between TT and VFI (Pearson r = 0.48, P < .01). All patients underwent great saphenous vein stripping. Six months later, the venous clinical severity score significantly improved with significant reductions in both VV and VFI values. TT 6 months postoperatively was also significantly shorter than that before surgical treatment (501 +/- 67 seconds, 340 +/- 38 seconds, respectively, mean +/- SD, P < .01). CONCLUSIONS Varicose veins could affect lymphatic function and delay lymphatic flow in the lower limbs. Derangement of lymph flow may correlate with the severity of clinical venous disease and/or the magnitude of venous reflux, which could be reversible with surgical treatment of venous incompetence.

Hemodynamic assessment of celiaco-mesenteric anastomosis in patients with pancreaticoduodenal artery aneurysm concomitant with celiac artery occlusion using flow-sensitive four-dimensional magnetic resonance imaging.

OBJECTIVES Many pancreaticoduodenal artery (PDA) aneurysms are associated with celiac artery (CA) stenosis. The pathogenesis of PDA aneurysm may be associated with hemodynamic changes due to CA stenosis/occlusion. The aim of this study was to assess the hemodynamic changes of celiaco-mesenteric anastomosis in patients with PDA aneurysms concomitant with CA occlusion using four-dimensional flow-sensitive magnetic resonance imaging (4D-Flow). METHODS 4D-Flow was performed preoperatively on five patients. Seven age- and sex-matched individuals were used as controls. Hemodynamic parameters such as flow volume and maximum flow velocity in PDAs, gastroduodenal arteries, common hepatic arteries, and superior mesenteric arteries were compared between both groups. Wall shear stress (WSS) and oscillatory shear index (OSI) were mapped in both groups. RESULTS In the patient group, 4D-Flow identified retrograde flow of both gastroduodenal arteries and common hepatic arteries. Heterogeneous distribution patterns of both WSS and OSI were identified across the entire PDA in the patient group. OSI mapping showed multiple regions with extremely high OSI values (OSI > 0.3) in all patients. All PDA aneurysms, which were surgically resected, were atherosclerotic. CONCLUSIONS 4D-Flow identified hemodynamic changes in celiaco-mesenteric arteries in patients with PDA aneurysms with concomitant CA occlusion. These hemodynamic changes may be associated with PDA aneurysm formation.

Distribution of phospholipid molecular species in autogenous access grafts for hemodialysis analyzed using imaging mass spectrometry

Arteriovenous fistulae (AVF) using vein grafts are frequently used for vascular access in hemodialysis. When superficial veins are used as autogenous access grafts for hemodialysis, atherosclerotic-like tissue degeneration often causes stenosis and obstruction. Although the differences between the pathology of degeneration in AVF and atherosclerosis (i.e., peripheral artery occlusive disease (PAD)) are known, their underlying molecular mechanisms are not. We determined the characteristic abnormal lipid metabolism of AVF. Oil red O staining clearly showed the accumulation of lipid molecules in AVF and PAD tissues. We found that the staining pattern was different between AVF and PAD tissues. The media and adventitia of AVF and the intima and media of PAD were intensely stained. Quantitative lipid analysis revealed that the amount of PL was significantly increased in AVF and PAD. Next, we performed matrix-assisted laser desorption/ionization imaging mass spectroscopy and determined the characteristic distribution of lysophosphatidylcholine (LPC) and phosphatidylcholine (PC) in AVF. The distribution patterns of LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) were consistent with the Oil red O staining images, suggesting that metabolisms related to LPC (1-acyl 16:0) and PC (diacyl 16:0/20:4) are altered in AVF.

Assessment of pelvic hemodynamics during an open repair of an infrarenal abdominal aortic aneurysm

PurposeTo assess the pelvic circulation during abdominal aortic aneurysm (AAA) repair by measuring the inferior mesenteric artery stump pressure (IMA-SP), penile blood flow, and gluteal blood flow.MethodsTwenty males were selected for this study. An aorto-bi-common iliac arteries (CIA) graft replacement was performed in ten patients (Group Bi-CIA). An aorto-right-CIA/left-external iliac artery (EIA) graft replacement was performed in five (Group Lt-EIA). The other five underwent an aorto-right-EIA/left-CIA anastomosis (Group Rt-EIA). The right graft limb was anastomosed first, followed by the left limb in all of the patients. Pelvic circulation was monitored during aortic reconstruction, including the IMA-SP index (IMA-SPI), penile brachial pressure index (PBI) by pulse-volume plethysmography, and gluteal tissue oxygenation metabolism with near-infrared spectroscopy by monitoring the gluteal tissue oxygenation index (TOI) bilaterally.ResultsThe PBI and bilateral gluteal TOI became depressed in all patients during proximal aortic clamping. However, there was no significant change in IMA-SPI in each group. The PBI and bilateral gluteal TOI in all groups recovered to the baseline values after completion of bilateral graft limb anastomosis.ConclusionsIMA-SPI is likely to reflect collateral circulation mainly from the superior mesenteric artery. The penile blood flow and bilateral gluteal blood flow therefore seem to be supplied via the bilateral hypogastric arteries or the profunda femoris arteries.

Early Experience with Fenestrated Stent Grafts for Treatment of Juxtarenal Aortic Aneurysm

BACKGROUND Fenestrated endovascular abdominal aneurysm repair (FEVAR) using branched arteries devices for visceral arteries is increasingly being used for the repair of juxtarenal aortic aneurysms (JAAs) in Europe, United States, Australia, New Zealand, and Asia. This study aimed to evaluate the technical feasibility and short-term results of FEVAR in treating JAAs in Japanese patients. METHODS AND RESULTS FEVAR with Cook fenestrated stent-graft (Cook Medical Inc., Bloomington, Indiana, USA) was performed for 5 patients at high risk for open repair of JAA. Seventeen visceral vessels were successfully accommodated with 12 fenestrations, and five visceral arteries with four scallops with a loss of renal artery. In one case, a type III endoleak occurred at a renal artery fenestration, and this had disappeared in the 1-month postoperative computed tomography (CT). The mean follow-up duration was 8 months. Iliac leg occlusion occurred in 1 case, which was treated with thrombectomy and additional leg device deployment. All patients had survived at the end of the follow-up period and continued their outpatient visits. CONCLUSIONS Implantation of a Cook fenestrated stent-graft incorporating the visceral arteries is technically feasible in high-risk Japanese patients with JAA and may be a viable alternative to current methods.

Elastic Stocking-Induced Foot Necrosis in a Patient with Severe Pneumonia

Elastic stockings (ES) are widely used for the prevention of venous thromboembolism. Here we report a case of foot ulcers induced by ES in patients with pneumonia and hypoxia. A 94-year-old woman was admitted for the treatment of pneumonia. The patient had been wearing an ES because of a history of deep vein thrombosis of the leg. Multiple foot ulcers occurred within 24 hours after the admission despite the absence of peripheral arterial occlusive disease. The ulcers took almost 5 months to heal. For patients with hypoxia, ES may further deteriorate local tissue hypoxia and thus should be used carefully.

Insufficient Lymph Drainage Causes Abnormal Lipid Accumulation and Vein Wall Degeneration

Objective: Previously, we analyzed human varicose veins (VV) using imaging mass spectrometry (IMS) and detected the abnormal accumulation of lipid molecules in the walls of VV, possibly due to insufficient lipid drainage by the lymphatic vessels. In this study, we created an animal model of lymphatic insufficiency to investigate the effects of insufficient lymph drainage on vein walls. Methods: In rats, the lymphatic collecting vessels surrounding the femoral vein were ligated on one side (the model tissue), which caused the local retention of lymphatic fluid in the perivascular tissue. The equivalent contralateral tissue was used as a control. A histological study of the femoral vein and the surrounding perivascular tissue was conducted. IMS was used to analyze the distribution of lipid molecules in the perivascular tissue. Results: Fourteen days after the procedure, the lymphatic vessels in the model tissue were significantly dilated. Furthermore, IMS revealed that the composition of the lipid molecules in the perivascular regions of the model tissue had altered. Compared with the control tissue, the model tissue exhibited marked perivascular accumulation of lysophosphatidylcholine (1-acyl 16:0), phosphatidylcholine (16:0/20:4), and triglycerides (52:2). Interestingly, the walls of the femoral veins running through the model tissue were 3.4-fold thicker than those of the femoral veins running through the control tissue. The number of tumor necrosis factor α-positive adipocytes was increased in the perivascular regions of the model tissue. Conclusion: The findings of this study indicated that the accumulation of lymphatic fluid due to insufficient lymph drainage changes the structure of vein walls, and such changes might be associated with chronic venous insufficiency. (This is a translation of Jpn J Phlebol 2015; 26: 227-235.).