Masanobu Namura

Brown adipose tissue: Evaluation with201Tl and99mTc-sestamibi dual-tracer SPECT

Brown adipose tissue is one kind of adipose tissue and regulates body temperature and balance of energy via non-shivering thermogenesis. The authors present a case that strongly suggested the presence of activated brown adipose tissue in the neck, shoulders and axillary space by increased18F-FDG uptake.99mTc-sestamibi and201Tl dual-tracer SPECT study showed increased 99mTc-sestamibi uptake and non-increased201? uptake in the corresponding18F-FDG uptake sites. Brown adipose tissue has dense mitochondria in the cells, which play an important role in thermogenesis.99mTc-sestamibi uptake and retention depend on the mitochondrial activity but201Tl uptake does not. Therefore, the activity of mitochondria in activated brown adipose tissue may explain the discrepant uptake between99mTc-sestamibi and201Tl.

A novel β-myosin heavy chain gene mutation, p.Met531Arg, identified in isolated left ventricular non-compaction in humans, results in left ventricular hypertrophy that progresses to dilation in a mouse model

Mutations in the betaMHC (beta-myosin heavy chain), a sarcomeric protein are responsible for hypertrophic and dilated cardiomyopathy. However, the mechanisms whereby distinct mutations in the betaMHC gene cause two kinds of cardiomyopathy are still unclear. In the present study we report a novel betaMHC mutation found in a patient with isolated LVNC [LV (left ventricular) non-compaction] and the phenotype of a mouse mutant model carrying the same mutation. To find the mutation responsible, we searched for genomic mutations in 99 unrelated probands with dilated cardiomyopathy and five probands with isolated LVNC, and identified a p.Met531Arg mutation in betaMHC in a 13-year-old girl with isolated LVNC. Next, we generated six lines of transgenic mice carrying a p.Met532Arg mutant alphaMHC gene, which was identical with the p.Met531Arg mutation in the human betaMHC. Among these, two lines with strong expression of the mutant alphaMHC gene were chosen for further studies. Although they did not exhibit the features characteristic of LVNC, approx. 50% and 70% of transgenic mice in each line displayed LVH (LV hypertrophy) by 2-3 months of age. Furthermore, LVD (LV dilation) developed in approx. 25% of transgenic mice by 18 months of age, demonstrating biphasic changes in LV wall thickness. The present study supports the idea that common mechanisms may be involved in LVH and LVD. The novel mouse model generated can provide important information for the understanding of the pathological processes and aetiology of cardiac dilation in humans.

Characterization of cartilaginous tumors with 201 Tl scintigraphy

Histological diagnosis and grading of cartilaginous tumors are closely correlated with patient prognosis; consequently, they are essential elements. We attempted to clarify the characteristics of2O1T1 uptake in various histological types of cartilaginous tumors and to assess its clinical value.MethodsTwenty-two cases with histologically proven cartilaginous tumors (3 enchondromas, 15 conventional chondrosarcomas (grade I = 9, II = 5, III = 1), 3 mesenchymal chondrosarcomas, and 1 de-differentiated chondrosarcoma) were examined retrospectively. Planar201Tl images were recorded 15 min following intravenous injection of2O1T1 (111 MBq).20lTl uptake in the tumor was evaluated visually employing a five-grade scoring system: 0 = no appreciable uptake, 1 = faint uptake above the background level, 2 = moderate uptake, 3 = intense uptake but lower than heart uptake and 4 = uptake higher than heart uptake.Results201Tl uptake scores were 0 in 3 of 3 enchondromas, 9 of 9 grade I, and 4 of 5 grade II conventional chondrosarcomas.201Tl uptake scores were 1 among 1 of 5 grades II and a grade III conventional chondrosarcoma. Mesenchymal chondrosarcoma and de-differentiated chondrosarcoma displayed2O1T1 uptake scores of 2 or 3.ConclusionsAbsence of elevated201Tl uptake in cartilaginous tumors was indicative of enchon-droma or low-grade conventional chondrosarcoma. However, in instances in which20lTl uptake is obvious, high-grade chondrosarcoma or variant types should be considered.

Antiplatelet therapy discontinuation and stent thrombosis after sirolimus-eluting stent implantation: Five-year outcome of the j-Cypher Registry

BACKGROUND The influence of antiplatelet therapy discontinuation on the incidence of stent thrombosis, especially very late stent thrombosis, after drug-eluting stent implantation has not been yet fully addressed. METHODS Relationship between antiplatelet therapy discontinuation and stent thrombosis up to 5years was evaluated in 12,812 consecutive patients undergoing sirolimus-eluting stents (SES) implantation in the j-Cypher registry. Data on status of antiplatelet therapy during follow-up were collected prospectively. RESULTS Median follow-up interval was 1699days (interquartile range, 1184-1928days). Incidences of definite stent thrombosis were 0.34% at 30days, 0.55% at 1year, and 1.6% at 5years. Dual antiplatelet therapy was maintained in 97.4%, 63%, and 43.9% of patients at 30days, 1year, and 5years, respectively. The rates of stent thrombosis in patients who discontinued both thienopyridine and aspirin were significantly higher in the time intervals of 31-365days, 2-3years and 3-4years, and tended to be higher in the time intervals of 1-2years and 4-5years than those in patients who continued both (31-365days: 1.26% versus 0.2%, P<0.001; 1-2years: 0.59% versus 0.15%, P=0.06; 2-3years: 1.35% versus 0.2%, P=0.004; 3-4years: 1.09% versus 0.25%, P=0.0496; 4-5years: 1.35% versus 0.43%, P=0.17). Patients who discontinued either thienopyridine or aspirin only did not have an excess of stent thrombosis in any time intervals. CONCLUSIONS In conclusion, discontinuation of both thienopyridine and aspirin, but not discontinuation of thienopyridine or aspirin only, was associated with an increased incidence of late and very late stent thrombosis up to 5years after SES implantation.

Impact of severe coronary disease associated or not associated with diabetes mellitus on outcome of interventional treatment using stents: results from HERZ (Heart Research Group of Kanazawa) analyses.

Percutaneous coronary intervention (PCI) using a drug-eluting stent (DES) leads to less re-stenosis than PCI using a bare metal stent (BMS), however there is still controversy whether use of a DES for severe coronary disease leads to an acceptable outcome in patients with diabetes mellitus (DM). In this study 8159 lesions were treated in 6739 patients (mean age 68.9 years) with coronary artery disease. Use of a DES significantly decreased the re-stenosis rate compared with BMS in both DM (9.6% versus 21.3%) and non-DM (9.5% versus 17.1%) patients. The re-stenosis rate was significantly higher in DM than in non-DM patients in the BMS group but not in the DES group. There was no statistically significant difference in event-free survival after stenting of patients with left main coronary artery (LMCA) disease between the BMS and DES groups. It was concluded that, compared with BMS, DES reduced re-stenosis in patients with DM, however, we advise careful treatment after using DES for severe coronary disease, including LMCA lesions, in patients with DM.

Serial cardiac influence of volume overload induced by interventional therapy for central venous stenosis or occlusion in chronic hemodialysis patients.

BACKGROUND Upper arm swelling and venous hypertension at arteriovenous fistula sites, and insufficiency of hemodialysis are induced by central venous lesions in chronic hemodialysis patients. Percutaneous transluminal angioplasty (PTA) for central venous lesions is first-choice treatment. Cardiac function can be evaluated by measuring the acute increase in venous return volume after PTA. METHODS We studied 6 cases of successful PTA for central venous stenotic or occluded lesions, and evaluated cardiac function by Swan-Ganz (SG) catheter and ultrasound echocardiography (UCG) at pre-, post-PTA, and on the following day. RESULTS Ejection fraction (EF) in 6 cases was 71.0 ± 5.5% on UCG. Two cases of subclavian venous stenosis, one case of subclavian venous occlusion, and three cases of brachiocephalic venous occlusion were enrolled. The reference diameter (RD) was 10.2 ± 4.9 mm, % diameter-stenosis (%DS) was 92.2 ± 12.2% at pre-PTA, and %DS at post-PTA was 21.7 ± 20.7%. There were no significant differences in pulmonary capillary-wedge, pulmonary artery, and right ventricular end-diastolic pressure in SG at pre- and post-PTA. The pressure of right atrium (RA) and cardiac output (CO) were significantly increased by PTA (RA pressure at pre-/post-PTA, 9.7 ± 2.9/11.7 ± 3.6 mmHg, p<0.05, CO at pre-/post-PTA 5.09 ± 2.07/5.45 ± 2.25 l/min, p<0.05). There were no significant differences in serial EF, left atrial and left ventricular diameters on UCG. However, the short-diameter of right ventricle (RV) and RA were significantly increased at post-PTA and recovered on the following day (RV short-diameter at pre-/post-/following-day PTA, 26.7 ± 3.5/32.5 ± 1.9/29.1 ± 1.7 mm, p<0.05; RA short-diameter at pre-/post-/following-day PTA, 30.2 ± 4.2/36.3 ± 2.4/32.1 ± 3.6mm, p<0.05). CONCLUSIONS Volume overload after PTA for central venous stenotic or occluded lesions in chronic hemodialysis patients resulted in increased RA and RV diameters. These changes were transient and completely recovered by the following day. PTA for central venous lesions in patients with normal EF can be performed without clinical cardiac problems.

Left ventricular ejection and filling rate measurement based on the automatic edge detection method of ECG-gated blood pool single-photon emission tomography

The objective of the present investigation was to determine the feasibility of assessing left ventricular systolic ejection and diastolic filling via the automatic edge detection method employing ECG-gated blood pool single-photon emission tomography (SPET GBP) data.MethodsThirtyfive patients, who had undergone both SPET GBP and ECG-gated equilibrium blood pool scintigraphy by the planar method (planar GBP), were enrolled in this study. Planar GBP was performed with a single-headed gamma camera. From the left anterior oblique projection, data were acquired at 24 frames/cardiac cycle with ECG-gating during the equilibrium state. SPET GBP was conducted utilizing a triple-headed gamma camera, with 60 projection views over 360 degrees by 60 sec per view, in 16 frames/cardiac cycle. In each frame, left ventricular volume was determined by automatic edge detection employing a quantitative gated SPET program. Additionally, the time-volume curve was fitted by the 4th harmonics of Fourier transform. Ejection fraction (EF, %), peak ejection rate (PER, /sec), peak filling rate (PFR, /sec) and mean filling rate during the initial one-third of diastolic time (1/3 FRm) were calculated from the fitted curve. These parameters were also calculated with planar GBP data.ResultLeft ventricular ejection and filling parameters were calculated by SPET GBP with the automatic edge detection program for all patient data. Correlation coefficients of EF, PER, PFR and 1/3 FRm between SPET and planar GBP were 0.91 (p > 0.001), 0.82 (p > 0.001), 0.78 (p > 0.001) and 0.74 (p > 0.001), respectively.ConclusionEjection and filling rates can be calculated using SPET GBP with the edge-detection software. These parameters displayed significant correlations with those values obtained via planar GBP. Additional studies are warranted to determine the reliability of parameters with SPET GBP.

Discrepant uptake between fluorine-18 fluorodeoxy glucose and Tc-99m sestamibi in bronchioloalveolar cell carcinoma

Several studies have shown the benefit of fluorine-18 fluorodeoxy glucose (FDG) imaging in the differentiation of solitary pulmonary nodules. The majority of malignant tumor have a higher glucose metabolic rate as compared to benign lesions. However, there is a considerable variety in glucose metabolic rate that depends on the aggressiveness and histological subtype of the tumor. Technetium-99m sestamibi (MIBI) is another tumor imaging agent for SPECT. We present a case of bronchioloalveolar cell carcinoma with a false negative finding in FDG imaging and a positive finding in MIBI imaging. This case clearly indicates that the FDG uptake and MIBI uptake might provide different information regarding characteristics of lung cancer.

Sirolimus-Eluting Stent Implantation for Ostial Left Anterior Descending Coronary Artery Lesions

Background—Ostial left anterior descending coronary artery (LAD) lesion has been regarded as a lesion subset unsuitable for coronary stenting. Long-term outcomes of sirolimus-eluting stent (SES) implantation for ostial LAD lesions have not been adequately evaluated. Methods and Results—Among 12 824 patients enrolled in the j-Cypher Registry, 3-year outcomes were compared between 481 patients with SES-treated ostial LAD lesions and 5369 patients with SES-treated nonostial proximal LAD lesions. Patients with ostial LAD lesions had similar incidences of target lesion revascularization (TLR) as those with nonostial proximal LAD lesions (9.4% versus 9.7%; P=0.98; adjusted hazard ratio [HR], 0.99; 95% CI, 0.7 to 1.36; P=0.94) and death/myocardial infarction (MI) (10.7% versus 11.4%; P=0.82; adjusted HR, 1.05; 95% CI, 0.76 to 1.4; P=0.77). Among the patients with ostial LAD lesions, those undergoing both main and side branch stenting (n=62) compared to main branch stenting alone (n=419) had a higher risk for TLR (adjusted HR, 4.65; 95% CI, 2.32 to 9.25; P<0.0001) but similar risk for death/MI (adjusted HR, 1.15; 95% CI, 0.49 to 2.41; P=0.73). In patients with main branch stenting alone, outcomes after crossover stenting across the circumflex coronary artery (n=225) were not different from those after ostial stenting (n=194) for TLR (adjusted HR, 0.77; 95% CI, 0.33 to 1.82; P=0.55) and for death/MI (adjusted HR, 1.54; 95% CI, 0.78 to 3.2; P=0.22). Conclusions—In terms of both safety and efficacy, 3-year outcomes of percutaneous coronary intervention using SES for ostial LAD lesions were comparable to those for nonostial proximal LAD lesions. Crossover stenting with a 1-stent approach might be a reasonable option in treating ostial LAD lesions.

Development of a novel catheter preventing the outflow of debris and thrombus on percutaneous transluminal angioplasty for hemodialysis access fistulas

If a large amount of debris or thrombus dislodges from a lesion because of dilation of the stenotic or occluded lesion in the hemodialysis access fistula when angioplasty is performed, it may move into the pulmonary artery via the central vein, resulting in pulmonary embolism. A novel sheath has been developed to prevent the outflow of debris or thrombus to the central vein. The catheter consists of a 5 F sheath introducer and a silicone balloon attached at the tip of the sheath. The silicon balloon is inflated via small inflation lumen on the shaft wall of the sheath. In the case of percutaneous transluminal angioplasty (PTA), the silicone balloon is inflated to block the blood flow by a mixture of contrast medium and physiological saline, and then dilate a stenotic or occluded lesion by PTA balloon. Next, the debris and thrombus are aspirated using the flush‐lumen of this device. Finally, the silicone balloon is deflated and the dilation of the lesion is confirmed. A case of hemodialysis access fistula graft with massive thrombotic occlusion was presented. This device enabled Fogarty procedure using PTA balloon and the blood flow of the graft was completely improved and a large amount of thrombus was removed. This novel device is useful to prevent the embolic complication of the intervention for hemodialysis access fistula.