Successful surgical management of mesenteric inflammatory veno-occlusive disease

BACKGROUND

The term "mesenteric inflammatory veno-occlusive disease (MIVOD)" is used to describe an ischemic injury resulting from phlebitis or venulitis that affects the bowel or mesentery in the absence of arteritis. MIVOD is difficult to diagnose because of its rarity and frequent confusion with other diseases. The incidence and etiology of MIVOD remain unclear; only a few cases have been reported. We describe a case of the successful surgical management of a patient with MIVOD with characteristic images.

CASE PRESENTATION

A 65-year-old Japanese man visited a hospital with the chief complaint of abdominal pain in January 2018. CT showed edema and thickening of the intestinal wall from the descending colon to the rectum. The patient was admitted to the hospital. Suspected diagnoses were enteritis, ulcerative colitis, amyloidosis, vasculitis, malignant lymphoma, and venous thrombus, but no definitive diagnosis was obtained. The patient was transferred to our hospital for the treatment of stenosis (located from the descending colon to the rectum) and bowel obstruction. An emergency transverse colostomy was performed. The sigmoid colon and mesentery were too rigid and edematous to resect. Colonic hemorrhage occurred 2 weeks after the surgery. With radiology intervention, coiling for the arteriovenous fistula in the descending colon was performed, and hemostasis was obtained. A colonoscopy at 6 months post-surgery showed neither ulceration nor stenosis in the rectum, indicating that the rectum could be preserved in the next surgery. However, severe stenosis in the descending and sigmoid colon remained unchanged. Ten months after the transverse colostomy, we performed a subtotal colectomy and ileorectal anastomosis, and an ileostomy was created. The sigmoid colon and mesentery were not so rigid compared to the first surgery's findings, and we were able to resect intestine and mesentery. Histopathology revealed phlebitis and venulitis, fibrinoid necrosis, and normal arteries, meeting the diagnostic criteria for MIVOD. Postoperatively, the patient showed no recurrence for 8 months.

CONCLUSION

Clinicians should consider MIVOD when examining a patient with intestinal ischemia. When MIVOD is suspected, the patient is indicated for surgery based on an accurate diagnosis and good prognosis.

92Transcatheter aortic valve implantation improves cerebral blood flow and cognitive function in elderly patients with aortic stenosis - Brain perfusion SPECT imaging study

Background

Cognitive impairment and depression are commonly noted in elderly frail patients with severe aortic stenosis (AS). However, their mechanisms and reversibility after treatment remain remain to be examined.

Purpose

In this study, we examined whether transcatheter aortic valve implantation (TAVI) increases cerebral blood flow (CBF) in cognitive/emotional brain areas, such as the hippocampus, in the elderly patients with severe AS.

Methods

We examined consecutive 15 right-handed patients with severe AS who were eligible for TAVI (median age 83.2 years, 12 (80%) women). We evaluated the following assessments both at baseline and 3 months after TAVI. Frailty was evaluated based on Fried scale, which consists of 5 items, including gait speed, cognitive function, weight loss, exhaustion, and inactivity. Frail and pre-frail were defined as greater than 3 and 1∼2 in the scale, respectively. Cognitive and emotional status were evaluated with Logical Memory (LM) II, Mini Mental State Examination (MMSE), and geriatric depression scale (GDS). Lower LM II (less than 4 points) and MMSE (less than 24 points) and higher GDS (more than 6 points) indicate worse memory, general cognitive function, and depressive symptoms, respectively. CBF images were recorded with 99mTc single-photon emission computed tomography and were analyzed using SPM12. Briefly, CBF images were firstly normalized to the standard Montreal Neurological Institute space. Then, a voxel-wise parametric analysis was conducted between normalized CBF images at baseline and those after TAVI (P<0.005 at each voxel). Continuous variables were presented as mean ± standard error (SE). Normality was assessed using the Shapiro-Wilk test. Continuous variables were compared with the use of paired t test. Linear mixed-model analysis was performed to evaluate changes in neuropsychological tests and CBF over time.

Results

In the present study, all patients were not robust but pre-frail (47.3%) or frail (53.7%). LM II score was significantly improved at 3 months after TAVI compared with baseline (baseline, 8.7 vs. 3 months, 13.8, P<0.01) (Figure A), whereas no significant changes in MMSE or GDS scores were noted (baseline, 24.6 vs. 3 months, 25.2 for MMSE; baseline, 4.3 vs. 3 months, 4.2 for GDS). Importantly, although no patients showed clinical symptoms or signs for transient ischemic attack or stroke after TAVI, CBF in the local regions, including the right hippocampus, was significantly increased after TAVI compared with baseline (P<0.005 at each voxel) (green arrowheads) (Figure B). Furthermore, CBF in the right hippocampus were positively correlated with LM II scores (P=0.017) (Figure C).

Figure 1

Conclusions

These results provide the first evidence that TAVI improves cerebral perfusion (especially that in the hippocampus) and cognitive functions in elderly patients with severe AS.

P3575Clinical importance of fractional flow reserve in patients with organic coronary stenosis and vasospastic angina

Background

Vasospastic angina (VSA), which is one of the important functional cardiac disorders, may also play a role in the pathogenesis of atherosclerosis. Conversely, organic coronary stenosis is also known as an independent predictor for poor clinical outcomes in VSA patients. Although VSA patients have a variable degree of organic coronary stenosis in clinical setting, the functional importance of organic stenosis in those patients remains to be elucidated.

Purpose

The aim of this study was to examine the clinical importance and prognostic impact of fractional flow reserve (FFR) in patients with VSA and organic coronary stenosis.

Methods

We enrolled 236 consecutive patients with suspected vasospastic angina who underwent acetylcholine provocation test for coronary spasm (M/F 148/88, 63.6±12.0 [SD] yrs.). Among them, 175 patients (74.1%) were diagnosed as having VSA, while the remaining non-VSA patients were regarded as controls (Group-C, n=61). We divided the VSA patients into 3 groups based on angiographical findings and FFR values; VSA with no organic stenosis (>50% luminal stenosis) (Group-N, n=110), organic stenosis and high FFR (≥0.80) (Group-H, FFR 0.87±0.05, n=36), and organic stenosis and low FFR (<0.80) (Group-L, FFR 0.71±0.07, n=29). We evaluated the incidence of major adverse cardiovascular events (MACE), including cardiovascular death (CVD), non-fatal myocardial infarction (MI), urgent percutaneous coronary intervention (PCI), and hospitalization due to unstable angina pectoris (UAP) during the median follow-up period of 656 days.

Results

The groups with organic stenosis (Groups H and L) were characterized by higher prevalence of diabetes mellitus (Group-C/N/H/L, 23.0/20.9/44.4/34.5%, P=0.03) and dyslipidemia (Group-C/N/H/L, 37.7/39.1/50.0/65.5%, P=0.03) as compared with Group-C. After provocation test, all VSA patients received calcium channel blockers (CCBs). In addition, 20 days (median) after provocation test, 26 patients (92.9%) in Group-L underwent elective PCI with coronary stents, while no patient underwent PCI in Groups N or H. The incidence of MACE during follow-up was significantly higher in Group-L (Group-C/N/H/L; 1.6/3.6/5.6/27.6%, log-rank P<0.001), whereas clinical outcomes were comparable among the remaining 3 groups (Figure). Importantly, all 8 patients with MACE in Group-L had poor outcomes (CVD/MI/urgent PCI/UAP; 2/1/3/2) despite complete revascularization and the prevention of coronary spasm with CCBs, indicating that they might be resistant to standard contemporary therapies. They were characterized by less frequent use of angiotensin convert enzyme inhibitor (0 vs. 47.6%, P=0.02) and higher prevalence of multi-vessel organic lesions (37.5 vs. 4.8%, P=0.052) compared with those without MACE.

Figure 1

Conclusions

These results provide the first evidence that evaluation of coronary functional abnormalities with FFR is useful for making therapeutic strategies in VSA patients with organic coronary stenosis.

P4158Marked impairment of endothelium-dependent digital vasodilatations in patients with microvascular angina compared with those with vasospastic angina

Background/Introduction

Nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) factor are the major endothelium-derived relaxing factors. NO plays an important role in conduit arteries, while the importance of EDH factor increases as the vessel size decrease in patients with microvascular angina (MVA) compared with those with vasospastic angina (VSA) remains to be fully elucidated.

Purpose

We evaluated the roles of NO and EDH factor in conduit (brachial) arteries and resistance (digital) arteries of the patients with MVA, VSA and comorbid MVA+VSA patients.

Methods

We enrolled 39 patients who underwent diagnostic cardiac catheterization and divided them into 3 groups based on acetylcholine (ACh) provocation test, index of microcirculation resistance (IMR), and coronary flow reserve (CFR); MVA (N=9, mean age 59.9±3.5 years), VSA (N=12, mean age 61.3±1.8 years), and comorbid MVA+VSA (N=18, mean age 64.0±2.2 years). Endothelium-dependent brachial and digital vasodilatations in response to intra-arterial infusion of bradykinin (BK, 25, 50, and 100 ng/min for 2 min) were simultaneously measured by ultrasonography and peripheral arterial tonometry, respectively. Measurements were repeated after oral administration of aspirin (486 mg) and intra-arterial infusion of NG-monomethyl-L-arginine (L-NMMA, 8μmol/min for 5 min) in order to inhibit the effects of vasodilator prostaglandins and NO, respectively. Finally, endothelium-independent brachial and digital vasodilatations in response to sublingual nitroglycerin (NTG, 0.3 mg) were measured in the same manner.

Results

In the brachial artery, dose-dependent vasodilatations to BK were comparable among the 3 groups, and L-NMMA equally attenuated the responses to BK (Figure 1). Endothelium-independent brachial vasodilatation in response to NTG was also comparable among the 3 groups. Surprisingly, dose-dependent digital vasodilatations to BK were almost absent in MVA patients compared with VSA or comorbid MVA+VSA group (Figure 2). Furthermore, the digital vasodilatations were unaffected by L-NMMA in VSA group, but were significantly reduced in comorbid MVA+VSA group (VSA, 16.8±15.1% vs. MVA+VSA, −0.23±6.2%, P<0.05), suggesting reduced EDH and compensatory role of NO in the latter group. In contrast, endothelium-independent digital vasodilatation in response to NTG was comparable among the 3 groups.

The main results of this study

Conclusions

These results provide the first evidence that endothelium-dependent digital vasodilatations (both NO and EDH factor) are markedly impaired in MVA patients compared with VSA or comorbid MVA+VSA patients, whereas the responses are comparable in the brachial artery among the 3 groups, suggesting the involvement of severe endothelial dysfunction in the pathogenesis of MVA.

2381Low-intensity pulsed ultrasound ameliorates DES-induced coronary adventitial inflammation and hyperconstricting responses in pigs in vivo - A novel non-invasive therapy for coronary inflammation

Background

We previously demonstrated that coronary adventitial inflammation plays important roles in the pathogenesis of coronary artery spasm, including drug-eluting stent (DES)-induced coronary hyperconstricting responses, in pigs and humans. Indeed, the coronary adventitia has recently attracted much attention as the important site for vascular inflammation. However, a direct therapeutic approach to the coronary adventitia remains to be developed. We have developed a non-invasive low-intensity pulsed ultrasound (LIPUS) therapy for angina, which exerts anti-inflammatory effects through improved coronary microcirculation.

Purpose

In this study, we aimed to examine whether our LIPUS therapy ameliorates DES-induced coronary hyperconstricting responses in pigs in vivo, and if so, what mechanisms are involved.

Methods

An everolimus-eluting stent (EES) was implanted into the left anterior descending (LAD) coronary artery in normal male pigs. They were randomly assigned to the LIPUS or the sham therapy groups. After EES implantation, in the LIPUS group, LIPUS (32 cycles, 193 mW/cm2) was applied to the heart at 3 different levels (proximal and distal stent edges and middle portion of the stent) through X-ray for 20 min at each level for every other day for 2 weeks (6 days in total) (Figs. 1A, 1B). The sham therapy group was treated in the same manner but without LIPUS. At 4 weeks after the procedure, we performed coronary angiography to examine coronary vasoconstricting responses to intracoronary serotonin in vivo. Finally, stented coronary vessels were harvested for immunohistochemistry of vasa vasorum, lymphatic vessels (LYVE-1), sympathetic nerve fibers (SNF), vascular inflammation (macrophages and IL-1β expression), Rho-kinase expression and activity as evaluated by phosphorylated myosin phosphatase target subunit-1 (pMYPT-1).

Results

Coronary vasoconstricting responses to intracoronary serotonin were significantly enhanced in the sham therapy group but were significantly suppressed in the LIPUS group at the DES edges in the LAD, whereas those responses were comparable at the non-DES implanted segments in the left circumflex (LCx) coronary arteries between the 2 groups. (Figs. 1C, 1D). Furthermore, in vivo lymph transport speed was significantly faster in the LIPUS group than in sham group (Figs. 1E–1G). Histological analysis showed that except vasa vasorum formation, the number of lymphatic vessels, adventitial inflammatory cells infiltration, Rho-kinase expression and activity were all significantly enhanced in the sham therapy group and were significantly suppressed in the LIPUS group (Figs. 1G–1K).

Figure 1

Conclusion

We were able to develop a non-invasive LIPUS therapy for coronary functional abnormalities caused by chronic adventitial inflammation in pigs in vivo, for which multiple beneficial effects appear to be involved (Fig. 1L).

3332Exercise training ameliorates vasodilator capacity of coronary microvessels in patients with vasospastic angina - A new therapeutic approach for the coronary functional disorder

Background

We have recently demonstrated that coronary vasospasm could develop in both epicardial coronary arteries and intramuscular coronary microvessels in patients with vasospastic angina (VSA). However, it remains to be examined whether vasodilator capacity of coronary microvessels is impaired in VSA patients and if so, whether exercise training could ameliorate vasodilator capacity of coronary microvessels on the top of calcium channel blockers. The effectiveness of exercise training is established for organic coronary artery disease but remained to be examined for VSA.

Purpose

We thus examined whether vasodilator capacity of coronary microvessels is impaired in VSA patients without organic coronary stenosis using an adenosine-stress dynamic computed tomography perfusion (CTP) that can measure absolute value of myocardial blood flow (MBF). We also examined whether exercise training ameliorates not only vasodilator capacity of coronary microvessels but also exercise capacity and frequency of angina attack.

Methods

In the first protocol, we measured MBF using CTP in consecutive 32 VSA patients with acetylcholine-induced diffuse coronary spasm in the left anterior descending coronary arteries (LAD) and 12 non-VSA controls. In the second protocol, we conducted a randomized controlled trial (RCT; Exercise VSA trial, UMIN: ehz745.008423996), where 20 VSA patients were randomly assigned to either exercise group (Ex group: supervised exercise training session for 30-min using bicycle ergometer, once/week at the hospital and more than 3 times/week at home) or non-exercise group (Non-Ex group) (n=10 each) (Figure A). Before and 3 months after exercise training, we measured MBF with adenosine-stress dynamic CTP and peak VO2 by cardiopulmonary exercise tests, and also assessed angina attack with Seattle Angina Questionnaire (SAQ).

Results

In the first protocol, CTP showed that adenosine-stress MBF was significantly decreased in the VSA group compared with the non-VSA group (VSA, 137.2±6.6 vs. Non-VSA, 174.4±10.7 ml/100g/min, P<0.01) (Figure B), although patient characteristics were comparable between the 2 groups. In the second protocol, exercise training was performed safely in all patients, and RCT showed that MBF was significantly increased in the Ex group compared with the non-Ex group (Figures C, D), although patient characteristics were also comparable between the 2 groups. Furthermore, peak VO2 was significantly increased in the Ex group compared with the non-Ex group (Figure E), and frequency of angina was significantly decreased in the Ex group compared with the non-Ex group (Figure F). Finally, there was a significant positive correlation between the extents of the changes in peak VO2 and the SAQ score for angina frequency in the Ex group (P<0.01, R=0.67).

Figures

Conclusions

These results provide the first evidence that vasodilator capacity of coronary microvessels is impaired in VSA patients, which can be ameliorated by exercise training.

P6166Radiomics-based machine learning versus histogram analysis and visual assessment to identify advanced atherosclerotic lesions on coronary computed tomography angiography

Background

Currently used coronary CT angiography (CTA) plaque classification and histogram-based methods have limited accuracy to identify advanced atherosclerotic lesions. Radiomics-based machine learning (ML) could provide a more robust tool to identify high-risk plaques.

Purpose

Our objective was to compare the diagnostic performance of radiomics-based ML against histogram-based methods and visual assessment of ex-vivo coronary CTA cross-sections to identify advanced atherosclerotic lesions as defined by histology.

Methods

Overall, 21 coronaries of seven hearts were imaged ex vivo with coronary CTA. From 95 coronary plaques 611 histological cross-sections were obtained and classified based-on the modified American Heart Association scheme. Histology cross-sections were considered advanced atherosclerotic lesions if early, late fibroatheroma or thin-cap atheroma was present. Corresponding coronary CTA cross-section were co-registered and classified into homogenous, heterogeneous, napkin-ring sign plaques based on plaque attenuation pattern. Area of low attenuation (<30HU) and average CT number was quantified. In total, 1919 radiomic parameters describing the spatial complexity and heterogeneity of the lesions were calculated in each coronary CTA cross-section. Eight different radiomics-based ML models were trained on randomly selected cross-sections (training set: 75% of the cross-sections) to identify advanced atherosclerotic lesions. Plaque attenuation pattern, histogram-based methods and the best ML model were compared on the remaining 25% of the data (test-set) using area under the receiver operating characteristic curves (AUC) to identify advanced atherosclerotic lesions using histology as a reference.

Results

After excluding sections with heavy calcium (n=32) and no visible atherosclerotic plaque on CTA (n=134), we analyzed 445 cross-sections. Based on visual assessment, 46.5% of the cross-sections were homogeneous (207/445), 44.9% heterogeneous (200/445) and 8.6% were with napkin-ring sign (38/445). Radiomics-based ML model incorporating 13 parameters significantly outperformed visual assessment, area of low attenuation and average CT number to identify advanced lesions (AUC: 0.73 vs. 0.65 vs. 0.55 vs. 0.53; respectively; p<0.05 for all).

Conclusions

Radiomics-based ML analysis may be able to improve the discriminatory power of CTA to identify high-risk atherosclerotic lesions.

P4156Coexistence and prognostic impacts of epicardial and microvascular coronary dysfunctions in patients with chest pain and unobstructive coronary artery disease - Involvement of Rho-kinase activation

Background

Although the importance of coronary functional abnormalities has been emerging, including epicardial coronary spasm (vasospastic angina, VSA) and coronary microvascular dysfunction (CMD), comprehensive evaluation of the abnormalities in the same population remains to be examined.

Purpose

We examined the significance of coronary functional abnormalities in a comprehensive manner for both epicardial and microvascular coronary arteries in patients with chest pain and unobstructive coronary artery disease (CAD) as well as their prognostic impacts.

Methods and results

We prospectively enrolled 187 consecutive patients with suspected angina and unobstructive coronary arteries (M/F 113/74, 63.2±12.3 [SD] yrs.). We performed acetylcholine (ACh) provocation tests for coronary spasm, followed by functional tests for coronary microvascular function, including coronary flow reserve (CFR) and index of microcirculation resistance (IMR) during hyperemic state induced by intravenous adenosine. Among the 187 patients, ACh test identified 128 patients with VSA (68%). There was no significant difference in age, sex, or prevalence of traditional coronary risk factors between the non-VSA and the VSA groups. The median IMR value was significantly higher in the VSA group than in the non-VSA group [17.5 (12.0, 25.3) vs. 14.7 (10.7, 17.8), P=0.02], whereas CFR values were comparable between the 2 groups [2.51 (1.72, 3.35) vs. 2.66 (1.85, 3.64), P=0.34]. During the median follow-up period of 893 days, major adverse cardiac events (MACE), including cardiac death, non-fatal myocardial infarction, and hospitalization due to unstable angina pectoris, occurred in 10 patients (5.3%). Multivariable analysis revealed that IMR correlated with the incidence of MACE [hazard ratio (HR) (95% confidence interval), 1.05 (1.02–1.09), P=0.002] and receiver-operating characteristics curve analysis identified IMR of 18.0 as the optimal cut-off value for the incidence of cardiac events. When we divided the patients into the following 4 groups according to the cut-off value of IMR (>18) and the presence or absence of VSA; G1, IMR <18 without VSA (n=45); G2, IMR ≥18 without VSA (n=14); G3, IMR <18 with VSA (n=67); and G4, IMR ≥18 with VSA (n=61), the Kaplan-Meier survival analysis showed a significantly worse prognosis in G4 compared with other 3 groups (HR [95% CI] 6.23 [1.21–118.46], P=0.002) (Figure 1). Importantly, intracoronary administration of fasudil, a Rho-kinase inhibitor, significantly ameliorated IMR in G4 (P<0.0001) (Figure 2A), and %changes in IMR in response to intracoronary fasudil were more evident in G4 compared with other 3 groups (P<0.0001) (Figure 2B).

Conclusions

These results provide the first evidence that in patients with chest pain and unobstructive CAD, epicardial coronary spasm and increased microvascular resistance are frequently coexisted with worse long-term prognosis, for which Rho-kinase activationmay be involved.

Tumorous CD10 Is More Strongly Related to the Progression of Urothelial Carcinoma than Stromal CD10

BACKGROUND/AIM

CD10 function in urothelial carcinoma (UC) remains controversial. We previously reported that miR-21 in UC may be a prognostic marker for cancer progression. The aim of this study was to examine the clinicopathological significance of CD10 expression in UC and its relationship with miR-21 expression.

MATERIALS AND METHODS

Immunohistochemistry for CD10 was performed on 232 UCs. CD10 expression in TCs and stroma was evaluated respectively, and its association with carcinogenesis and survival was analyzed.

RESULTS

High tumorous CD10 was significantly associated with higher tumor stage, histological grade and vessel infiltration, and poorer prognosis, whereas stromal CD10 was significantly associated with younger age, higher tumor stage, and vessel infiltration. On multivariable analysis, CD10 expression in TCs, miR-21 expression in TCs and TS, and tumor stage were independent prognostic factors.

CONCLUSION

Tumorous CD10 is more strongly related to progression of UC than stromal CD10 and is an independent factor for UC prognosis.

Mesenchymal Stem Cell Marker Expression in Gastric Cancer Stroma

BACKGROUND/AIM

Spindle-shaped stromal cells of tumors are derived from various cellular origins, including mesenchymal stem cells (MSCs). MSCs express CD73, CD90 and CD105 antigens. Herein, the aim was to investigate the association between the expression of specific MSC markers in gastric cancer stromal cells and the clinicopathological features of the disease.

MATERIALS AND METHODS

The expression of CD73, CD90 and CD105 in spindle-shaped cancer stromal cells was studied by immunohistochemistry in tissue arrays containing 546 gastric cancer cases. Univariate and multivariate analyses were performed to evaluate the association of MSC marker expression with clinicopathological variables.

RESULTS

Spindle-shaped cancer stromal cells expressing the MSC markers CD73, CD90 or CD105 were associated with larger tumor size, advanced cancer, venous infiltration, lymphatic infiltration, and lymph node metastasis. Statistical analysis demonstrated that the presence of CD105-positive spindle cells was an independent prognostic factor of advanced cancer, lymph node metastasis and EBV infection in multivariate analysis.

CONCLUSION

Spindle-shaped gastric cancer stromal cells expressing CD73, CD90 or CD105 are involved in disease progression, and among them, CD105-positive cells are strongly associated with poor prognosis.

[Primary central nervous system methotrexate associated lymphoproliferative disorders in a patient with rheumatoid arthritis]

We report on a 52-year-old woman with rheumatoid arthritis (RA) who developed methotrexate associated lymphoproliferative disorders (MTX-LPD) in the central nervous system (CNS) in the course of immunosuppressive therapy for RA. The patient was admitted because of monoplegia in her left hand. She had been receiving methotrexate (MTX) for her RA for several years and etanercept had also been introduced because of a worsening of the arthritis six months before admission. Brain MRI revealed multiple lesions with enhancement scattered throughout both hemispheres. ¹⁸F-fluorodeoxyglucose-positron emission tomography/computed tomography showed abnormal accumulation suggesting malignancy in the right frontal lobe where abnormal enhancement was observed on the MRI. A brain biopsy was performed at the identified site and it confirmed diffuse large B-cell lymphoma (DLBCL). We therefore diagnosed her as MTX-LPD. According to previous reports, most MTX-LPD cases tend to show regression after the cessation of MTX. However, our case showed no regression and even needed chemotherapy. The patient had a poorer prognosis than previous cases and died 17 months after the onset. Although it is an uncommon complication, particularly in the CNS, MTX-LPD should be considered as a critical differential diagnosis if a patient receiving MTX develops central nervous system lesions. Immediate medical intervention including brain biopsy is required.

Excitation of the Isovector Spin Monopole Resonance via the Exothermic ^{90}Zr(^{12}N,^{12}C) Reaction at 175 MeV/u

The (^{12}N, ^{12}C) charge-exchange reaction at 175  MeV/u was developed as a novel probe for studying the isovector spin giant monopole resonance (IVSMR), whose properties are important for better understanding the bulk properties of nuclei and asymmetric nuclear matter. This probe, now available through the production of ^{12}N as a secondary rare-isotope beam, is exothermic, is strongly absorbed at the surface of the target nucleus, and provides selectivity for spin-transfer excitations. All three properties enhance the excitation of the IVSMR compared to other, primarily light-ion, probes, which have been used to study the IVSMR thus far. The ^{90}Zr(^{12}N,^{12}C) reaction was measured and the excitation energy spectra up to about 70 MeV for both the spin-transfer and non-spin-transfer channels were deduced separately by tagging the decay by γ emission from the ^{12}C ejectile. Besides the well-known Gamow-Teller and isobaric analog transitions, a clear signature of the IVSMR was identified. By comparing with the results from light-ion reactions on the same target nucleus and theoretical predictions, the suitability of this new probe for studying the IVSMR was confirmed.

Estimation of the following Cardiac Output Using Sympathetic Tone and Hemodynamics for the Control of a Total Artificial Heart

A sympathetic neurogram is potentially useful for the development of a real time total artificial heart (TAH) control system. We used sympathetic tone and hemodynamic derivatives to estimate the following cardiac output in acute animal experiments using adult mongrel dogs. Moving averages of the mean left atrial pressure and mean aortic pressure were used as parameters of the preload and afterload, respectively. Renal sympathetic nerve activity (RSNA) was employed as a parameter of sympathetic tone. Equations for the following cardiac output were calculated using multiple linear regression analysis of the time series data. A significant correlation was observed between the estimated and following measured cardiac output. These results suggest the potential usefulness of the sympathetic neurogram for the real time TAH automatic control system.