Keiichi Nakagawa

Frequency and Clinical Implications of Fluid Dynamically Significant Diffuse Coronary Artery Disease Manifest as Graded, Longitudinal, Base-to-Apex Myocardial Perfusion Abnormalities by Noninvasive Positron Emission Tomography

BACKGROUNDnDiffuse coronary atherosclerosis is the substrate for plaque rupture and coronary events. Therefore, in patients with mild arteriographic coronary artery disease without significant segmental dipyridamole-induced myocardial perfusion defects, we tested the hypothesis that fluid dynamically significant diffuse coronary artery narrowing is frequently manifest as a graded, longitudinal, base-to-apex myocardial perfusion abnormality by noninvasive PET.nnnMETHODS AND RESULTSnIn this study, 1001 patients with documented coronary artery disease by coronary arteriography showing any visible coronary artery narrowing underwent rest-dipyridamole PET perfusion imaging. Quantitative severity of dipyridamole-induced, circumscribed, segmental PET perfusion defects was objectively measured by automated software as the minimum quadrant average relative activity indicating localized flow limiting stenoses. Quantitative severity of the graded, longitudinal, base-to-apex myocardial perfusion gradient indicating fluid dynamic effects of diffuse coronary artery narrowing was objectively measured by automated software as the spatial slope of relative activity along the cardiac longitudinal axis.nnnCONCLUSIONSnIn patients with mild arteriographic disease without statistically significant dipyridamole-induced segmental myocardial perfusion defects caused by flow-limiting stenoses compared with normal control subjects, there was a graded, longitudinal, base-to-apex myocardial perfusion gradient significantly different from normal control subjects (P=0. 001) that was also observed for moderate to severe dipyridamole-induced segmental perfusion defects (P=0.0001), indicating diffuse disease underlying segmental perfusion defects; 43% of patients with or without segmental perfusion defects demonstrated graded, longitudinal, base-to-apex perfusion abnormalities beyond +/-2 SD of normal control subjects, indicating diffuse coronary arterial narrowing by noninvasive PET perfusion imaging.

Combined intense lifestyle and pharmacologic lipid treatment further reduce coronary events and myocardial perfusion abnormalities compared with usual-care cholesterol-lowering drugs in coronary artery disease ☆

OBJECTIVESnThe purpose of this study was to determine if combined intense lifestyle and pharmacologic lipid treatment reduce myocardial perfusion abnormalities and coronary events in comparison to usual-care cholesterol-lowering drugs and whether perfusion changes predict outcomes.nnnBACKGROUNDnLifestyle and lipid drugs separately benefit patients with coronary artery disease (CAD).nnnMETHODSnA total of 409 patients with CAD, who underwent myocardial perfusion imaging by dipyridamole positron emission tomography at baseline and after 2.6 years, had quantitative size/severity of perfusion defects measured objectively by automated software with follow-up for five additional years for coronary artery bypass graft, percutaneous coronary intervention, myocardial infarction, or cardiac death. Patients were categorized blindly according to prospective, predefined criteria as poor treatment without diet or lipid drugs, or smoking; moderate treatment on American Heart Association diet and lipid-lowering drugs or on strict low-fat diet (<10% of calories) without lipid drugs; and maximal treatment with diet <10% of calories as fat, regular exercise, and lipid active drugs dosed to target goals of low-density lipoproteins <2.3 mmol/l (90 mg/dl), high-density lipoproteins >1.2 mmol/l (45 mg/dl), and triglycerides <1.1 mmol/l (100 mg/dl).nnnRESULTSnOver five years, coronary events occurred in 6.6%, 20.3%, and 30.6% of patients on maximal, moderate, and poor treatment, respectively (p = 0.001). Size/severity of perfusion abnormalities significantly decreased for patients receiving maximal treatment and increased for patients undergoing moderate and poor treatment (p = 0.003 and 0.0001, respectively). Combined intense lifestyle change plus lipid active drugs and severity/change of perfusion abnormalities independently predicted cardiac events.nnnCONCLUSIONSnIntense lifestyle and pharmacologic lipid treatment reduce size/severity of myocardial perfusion abnormalities and cardiac events compared with usual-care cholesterol-lowering drugs. Perfusion changes parallel treatment intensity and predict outcomes.

Prognostic Utility of Myocardial Blood Flow Assessed by N-13 Ammonia Positron Emission Tomography in Patients With Idiopathic Dilated Cardiomyopathy

Previous studies in patients with idiopathic dilated cardiomyopathy (IDC) have suggested that myocardial perfusion is impaired and spatially heterogeneous in such cases. Our objective was to identify any association between an abnormality in myocardial perfusion and the prognosis of patients with IDC. We collected data on N-13 ammonia positron emission tomography (PET) studies performed in 26 patients with IDC (9 nonsurvivors, 17 survivors) and in 8 normal control subjects. Regional myocardial blood flow (rMBF) was quantified using N-13 ammonia positron emission tomography and the Simple flow model. The spatial heterogeneity of myocardial perfusion was assessed by calculating the coefficient of variance of rMBF. Mean rMBF of the survivors was significantly lower (0.54 +/- 0.13 ml/min/g) than that of control subjects (0.66 +/- 0.06 ml/min/g) (p = 0.03 vs control), but did not differ significantly between nonsurvivors (0.58 +/- 0.15 ml/min/g) and control subjects. The coefficient of variance of rMBF was significantly higher in nonsurvivors than in either survivors or control subjects (0.24 +/- 0.08 vs 0.15 +/- 0.08, p = 0.007, and 0.16 +/- 0.05, p = 0.03, respectively). The probability of 3-year survival (Kaplan-Meier method) was 33.0% in subjects whose coefficient of variance of rMBF was above the median compared with 90.0% in subjects whose coefficient of variance of rMBF was below the median (p = 0.01). The probability of 3-year survival did not differ among subjects whose mean rMBF was above versus below the median (61.5% vs 62.9%, respectively). The results suggest that the prognosis of patients with IDC is associated with the spatial heterogeneity of myocardial perfusion, not with initial absolute rMBF.

Three dimensional segmented myocardial perfusion images by selective intracoronary injection of contrast using 256 slice cone beam computed tomography

Information of the segmented left ventricular (LV) area supplied by every coronary artery is potentially useful for strategy and practice of percutaneous coronary intervention, coronary artery bypass surgery, or percutaneous transluminal septal myocardial ablation (PTSMA).1,2nnMyocardial contrast echocardiography (MCE) with intracoronary contrast injection has been used to evaluate the segmented LV area supplied by a coronary artery but it is invasive and evaluation of myocardial enhancement by ultrasound contrast material may depend upon the skill of the investigator.1nnWith a prototype high speed cone beam computed tomography (CT) apparatus employing 256 detector rows (Athena, Sony-Toshiba), an entire heart can be imaged within a single gantry rotation.3,4 Using this technique, combined with selective intracoronary injection of contrast, we determined the segmented LV area supplied by every coronary artery selectively.nnTwo domestic pigs (20 kg each) were anaesthetised with isoflurane, and catheters positioned in the left anterior descending branch (LAD) of the coronary artery in pig 1 and the left circumflex branch (LCx) in pig 2, via the femoral arteries. The heart rate of pigs ranged between 70–80 beats per minute.nnScan conditions for the 256 slice cone beam CT were: 120 kV, 200 mA, 1.0 second exposure, 1.0 second gantry rotation time, 0.5 mm slice thickness, and 256×0.5 mm slice collimation. For comparison, those for the 16 slice multislice CT scanner routinely used at our institute (SOMATOM Sensation 16, Siemens) were: …

Transition From Left Ventricular Hypertrophy to Massive Fibrosis in the Cardiac Variant of Fabry Disease

A 43-year-old male patient with cardiac Fabry disease was followed up by single-photon emission computed tomography (SPECT) and 18F-deoxyglucose (FDG) positron emission tomography (PET) examinations from 1992 onward. At first, he was thought to have concentric left ventricular (LV) hypertrophy, as determined by echocardiography (LV apex wall thickness, 21 mm; diastolic interventricular septum wall thickness, 25 mm; diastolic LV posterior wall thickness, 29 mm; ejection fraction, 76%); however, a diagnosis of cardiac Fabry disease was defined by endomyocardial biopsy and decreased α-galactosidase A activity of the peripheral lymphocyte in 1996. Extracardiac signs of Fabry disease were not detected at that time.nnIn 1992, a PET study after overnight fasting showed increased uptakes of FDG at the apical and lateral walls, whereas PET scanning after oral glucose loading showed a mildly reduced uptake of FDG. The uptakes of FDG were reduced in the apical and lateral walls of the LV on glucose loading images (Figure 1A, lower panel), whereas the uptakes of FDG were increased in the same regions on the fasting images (Figure 1A, upper panel). This mirror-image pattern of uptakes suggested myocardial ischemia at the apical and lateral walls. In 1996, SPECT and PET studies showed …

Carotid arterial distensibility is an important determinant of improvement in autonomic balance after successful coronary angioplasty.

Objective To determine whether arterial distensibility influences improvement of autonomic imbalance after left ventricular wall motion (LVWM) abnormality has been improved by percutaneous transluminal angioplasty (PTCA) in patients with ischemic heart disease (IHD). Methods and Results The following variables were assessed before and 3 months after PTCA in 63 patients with IHD who had a successful PTCA: heart rate variability (standard deviation of all normal R—R intervals [SDNN] measured from 24 h Holter electrocardiograms), baroreceptor sensitivity (determined by the phenylephrine injection method), and carotid artery distensibility (determined by ultrasonography). Abnormalities of LVWM were assessed by cineventriculography. In a multivariate analysis, carotid artery distensibility before PTCA and changes in LVWM abnormality before and after PTCA were independently associated with changes in baroreceptor sensitivity and SDNN (P<0.05). Patients were divided into two groups: one with impaired and one group with unimpaired initial carotid artery distensibility. After PTCA, LVWM was improved significantly in both groups, but baroreceptor sensitivity and SDNN were improved significantly (respectively from 5.0 ± 3.3 to 5.9 ± 3.9 ms/mmHg, P<0.01 and from 111 ± 47 to 128 ± 54 ms, P< 0.01) only in patients with well-preserved carotid artery distensibility. Conclusions The beneficial effect of PTCA on autonomic balance was greater in patients with well-preserved carotid artery distensibility than in those with impaired carotid artery distensibility. These results suggest that the pathophysiological state of arterial distensibility may modify the autonomic balance even after myocardial ischemia-related LVWM abnormalities are improved.

Buerger's disease-like vasculitis associated with Kimura's disease

A 46-year-old man was first diagnosed as Buergers disease according to his clinical and radiological features because he had no evidence of parasitic, allergic and connective tissue disease. Soft subcutaneous nodules suspected of lymphadenopathy on the bilateral inguinal regions were recognized after admission. Positron emission tomography scan showed the increased uptake of (18)F-fluoro-2-deoxyglucose in the bilateral inguinal regions. We finally diagnosed him as Kimuras disease based on pathologic findings and laboratory data, and started steroid therapy. The uptake of (18)F-fluoro-2-deoxyglucose disappeared and his leg pain was improved after the treatment. This is the first case report presenting a patient of Kimuras disease with Buergers disease-like vasculitis who was demonstrated by positron emission tomography.

Demonstration of Multislice Computed Tomography of Graft Destruction and Rupture to the Pericardium After Replacement of Ascending Aorta for Stanford Type-A Dissection

A 57-year-old man went to a hospital complaining of chest pain and was diagnosed with a Stanford Type-A aortic dissection that continued through the aortic arch and descending aorta to the whole abdominal aorta. He therefore underwent graph replacement of the ascending aorta.nnAfter 1 month, he experienced dyspnea and came to our hospital. Chest x-ray revealed cardiac enlargement. Transthoracic echocardiogram revealed massive pericardial effusion (PE) but no cardiac tamponade. An enhanced multislice computed tomography …