Catheter-ablation of ventricular tachycardia in patients with coronary artery disease: influence of the endocardial substrate size on clinical outcome

Ablation of symptomatic ventricular tachycardia (VT) in patients with coronary artery disease is frequently performed using the three dimensional mapping system CARTO. In the amplitude map, bipolar potentials of <1.5 mV are considered abnormal and represent damaged myocardium due to previous infarction. This pathological electrical area can be arrhythmogenic, serving as the substrate for reentrant VT. The purpose of this study was to correlate the size of the endocardial substrate with the success of VT catheter ablation. Included in this retrospective analysis were 69 consecutive patients with coronary artery disease who underwent ablation for symptomatic clinical VT using CARTO. The voltage maps were analyzed and the area with abnormal bipolar electrograms (<1.5 mV) was determined using geometric approximation models. The area of abnormal electrograms was divided into three sizes: small (≤15 cm²; 11 patients), medium (16–99 cm²; 50 patients), and large (≥100 cm²; 8 patients). Patient characteristics were not different between the three substrate groups in regard to age, tachycardia cycle length, or number of radiofrequency applications, however differed significantly between the small, medium and large group in regard to left ventricular ejection fraction (44 ± 12% vs. 32 ± 9% vs. 21 ± 7%, respectively; P = 0.001). Overall, there was a significant correlation between myocardial infarction locations and endocardial substrate sizes (P = 0.031), such that 73% of small substrates were found after inferior myocardial infarctions, and 100% of large substrates after anterior and multiple myocardial infarctions (P = 0.003). After ablation, inducibility of ventricular arrhythmias was more rare in patients with small substrates compared to patients with medium or large substrates (small substrates: 9%, medium and large substrates: 43%, P = 0.043). Although during follow-up of 25 ± 17 months (1 day to 72 months) there was no significant difference between endocardial substrate sizes in regard to recurrence rates (small: 27%, medium: 38%, large: 50%, P = 0.588), patients with a small substrate did not have fast VT or ventricular fibrillation (VF), in contrast to 30% and 38% of patients with medium and large substrates, respectively. We conclude that in patients with coronary artery disease a small area of low amplitude bipolar potentials (≤15 cm²) was seen more often after inferior myocardial infarction than after anterior and multiple infarctions. After ablation, patients with small substrates were rarely inducible and showed a more benign course during follow-up (trend towards fewer arrhythmia recurrences and no fast VT or VF). As a result smaller arrhythmogenic substrates appear to be better amenable to catheter ablation than larger substrates.     

Videofluorography and pulsed fluoroscopy using a 512 X 512-pixel digital image system

The combination of videofluorography and pulsed fluoroscopy using an analog videodisc system has previously been investigated with regard to image quality and potential for dose reduction. The authors found that the system could be improved still further by replacing the analog disc with a 512 X 512-pixel digital image system, thereby increasing fluoroscopic image quality and permitting stored images to be recorded with a multiformat camera. The pulsed method is compared with low-dose-rate fluoroscopy, in which a continuous image is obtained at 1/4 of the normal rate. Whereas image quality using a low dose rate was inadequate for any useful purpose, pulsed fluoroscopy was sufficient for all but the most critical stages of the examination.     

磷酸三钙骨水泥骨长入的实验

目的:找出磷酸三钙骨水泥中磷酸三钙合适的比例(既能成骨又不影响骨水泥的机械性能),并观察磷酸三钙骨水泥中在动物实验中骨长入的特点。方法:①磷酸三钙比例的筛选:根据骨粒骨水泥的研究基础,将普通骨水泥(上海第二医科大学第九人民医院科技开发公司出品)中加入30%,35%,40%的直径200～300μm能成骨的磷酸三钙颗粒(法国Bio-LuCo.提供),测试其抗压强度和弹性模量,找出合适的比例。②动物实验:将25只成年新西兰大白兔随机分成术后2,4,8,12,16周组5组,每组5只。无菌下在两侧股骨远端垂直于股骨做直径6mm,长12mm的圆柱样缺损,两侧随机填入35%磷酸三钙骨水泥(实验侧)和普通骨水泥(对照侧)进行骨长入的观察。分别于术后2,4,8,12和16周取材,观察骨水泥表面的骨生长和机械强度变化。结果:①随着磷酸三钙的比例增加,磷酸三钙骨水泥的抗压强度逐渐下降,而其弹性模量则逐渐上升(P<0.05),加入35%磷酸三钙时抗压强度为(86.30±0.57)MPa,弹性模量为(2.80±0.16)GPa,比例合适。②磷酸三钙骨水泥植入兔股骨2周时表面无明显变化,4周即开始有表面粗糙,但表面骨组织附着不明显,植入8周时骨水泥表面少量骨组织附着;12周骨水泥表面骨组织附着明显;16周骨水泥表面骨组织附着明显增多。对照侧仅见一薄层纤维结缔组织。③磷酸三钙骨水泥植入兔股骨第4周时抗压强度低于植入第2周[(83.50±1.21),(85.20±0.85)MPa,P<0.05],随后上升,至植入第16周时为(87.10±1.00)MPa(P<0.05)。弹性模量在植入12周时低于植入第2周[(2.30±0.16),(2.70±0.15)GPa,P<0.05],但在16周时上升为(2.80±0.16)GPa]。结论:①磷酸三钙骨水泥中磷酸三钙的比例35%最为合适。②随着骨水泥表面的磷酸三钙颗粒被吸收和新骨长入,具备部分生物活性,机械强度符合骨缺损充填的基本要求。     

Effects of prolonged intensive lipid-lowering therapy on the characteristics of carotid atherosclerotic plaques in vivo by MRI: a case-control study

High-resolution magnetic resonance imaging (MRI) with flow suppression not only provides useful information on luminal and wall areas of the carotid artery but also can identify the principal tissue components of the carotid atherosclerotic plaque. The effects of intensive lipid-lowering therapy on these MRI tissue characteristics were examined in patients with coronary disease (CAD). Eight CAD patients who have been receiving intensive lipid-lowering treatment (niacin 2.5 g/d, lovastatin 40 mg/d, and colestipol 20 g/d) for 10 years in the Familial Atherosclerosis Treatment Study (FATS) follow-up were randomly selected from among 60 such treated patients. Eight CAD patients who were matched to the treated patients for age (+/-3 years), baseline low density lipoprotein (+/-5 mg/dL), and triglycerides (+/-50 mg/dL) but who had never been treated with lipid-lowering drugs were selected as controls. For each of these 32 carotid arteries, luminal and plaque areas were measured by planimetry, in a blinded protocol, from the magnetic resonance image that showed most plaque. Fibrous tissue, calcium, and lipid deposits were identified on the basis of established criteria. Plaque composition was estimated as a fraction of total planimetered area. Patients treated with 10-year intensive lipid-lowering therapy, compared with control subjects, had significantly lower low density lipoprotein cholesterol levels (84 versus 158 mg/dL, respectively; P<0.001) and higher high density lipoprotein cholesterol levels (51 versus 37 mg/dL, respectively; P<0.001). As a group, treated patients, compared with untreated control subjects, had a smaller core lipid area (0.7 versus 10.2 mm(2), respectively; P=0.01) and lipid composition (1% versus 17%, respectively). Group differences in luminal area (55 [treated] versus 44 [control] mm(2), P=NS) and plaque area (58 [treated] versus 64 [control] mm(2), P=NS) tended to favor treatment. MRI appears useful for estimating carotid plaque size and composition. Hyperlipidemic CAD patients frequently (97%) have at least moderate (>/=40% area stenosis) carotid plaque. In this case-control study, prolonged intensive lipid-lowering therapy is associated with a markedly decreased lipid content, a characteristic of clinically stable plaques.     

Magnetic Resonance Imaging Outcomes From a Comprehensive Magnetic Resonance Study of Children With Fetal Alcohol Spectrum Disorders

Background: Magnetic resonance (MR) technology offers noninvasive methods for in vivo assessment of neuroabnormalities. Methods: A comprehensive neuropsychological/psychiatric battery, coupled with MR imaging, (MRI), MR spectroscopy (MRS), and functional MRI (fMRI) assessments, were administered to children with fetal alcohol spectrum disorders (FASD) to determine if global and/or focal abnormalities could be identified, and distinguish diagnostic subclassifications across the spectrum. The 4 study groups included: (i) fetal alcohol syndrome (FAS)/partial FAS (PFAS); (ii) static encephalopathy/alcohol exposed (SE/AE); (iii) neurobehavioral disorder/alcohol exposed (ND/AE) as diagnosed with the FASD 4‐Digit Code; and (iv) healthy peers with no prenatal alcohol exposure. Presented here are the MRI assessments that were used to compare the sizes of brain regions between the 4 groups. The neuropsychological/behavioral, MRS, and fMRI outcomes are reported separately. Results: Progressing across the 4 study groups from Controls to ND/AE to SE/AE to FAS/PFAS, the mean absolute size of the total brain, frontal lobe, caudate, putamen, hippocampus, cerebellar vermis, and corpus callosum length decreased incrementally and significantly. The FAS/PFAS group (the only group with the 4‐Digit FAS facial phenotype) had disproportionately smaller frontal lobes relative to all other groups. The FAS/PFAS and SE/AE groups [the 2 groups with the most severe central nervous system (CNS) dysfunction] had disproportionately smaller caudate regions relative to the ND/AE and Control groups. The prevalence of subjects in the FAS/PFAS, SE/AE, and ND/AE groups that had 1 or more brain regions, 2 or more SDs below the mean size observed in the Control group was 78, 58, and 43%, respectively. Significant correlations were observed between size of brain regions and level of prenatal alcohol exposure, magnitude of FAS facial phenotype, and level of CNS dysfunction. Conclusions: Magnetic resonance imaging provided further validation that ND/AE, SE/AE, and FAS/PFAS as defined by the FASD 4‐Digit Code are 3 clinically distinct and increasingly more affected diagnostic subclassifications under the umbrella of FASD. Neurostructural abnormalities are present across the spectrum. MRI could importantly augment diagnosis of conditions under the umbrella of FASD, once population‐based norms for structural development of the human brain are established.     

Protective effect of Sida cordata leaf extract against CCl4 induced acute liver toxicity in rats

ObjectiveTo investigate the hepatoprotective potential of Sida cordata (Malvaceae) (S. cordata) in experimental rats to validate its traditional claim.MethodsWister albino rats were divided into 6 groups: Group I served as control; Group II served as hepatotoxic (CCl₄ treated) group; Group III, IV and V served as (100, 200 and 400 mg/kg b.w.) S. cordata leaf extract (SCLE) treated groups; Group VI served as positive control (Silymarin) treated group. Liver marker enzymes serum glutamate oxyloacetic transaminase, serum glutamic pyruvic transaminase, pancreatic enzymatic antioxidants superoxide dismutase (SOD), lipid peroxidation, catalase (CAT), reduced glutathione (GSH) were measured and compared along with histopathological studies.ResultsObtained results show that the treatment with SCLE significantly (P<0.05-<0.001) and dose-dependently reduced CCl₄ induced elevated serum level of hepatic enzymes. Furthermore, SCLE significantly (up to P<0.001) reduced the lipid peroxidation in the liver tissue and restored activities of defence antioxidant enzymes GSH, SOD and CAT towards normal levels, which was confirmed by the histopathological studies.ConclusionsThe results of this study strongly indicate the protective effect of SCLE against CCl₄ induced acute liver toxicity in rats and thereby scientifically support its traditional use.     

MR neurography and muscle MR imaging for image diagnosis of disorders affecting the peripheral nerves and musculature

Recent advances in the technology of MR imaging are beginning to transform the fundamental methodology of diagnostic evaluations in neuromuscular disorders. When properly implemented, MR neurography is capable of providing high-quality information about nerve compression, nerve inflammation, nerve trauma, systemic neuropathies, nerve tumors, and recovery of nerve from pathologic states. Muscle MR imaging can identify denervation on a precise anatomic basis, document the progression of various conditions causing myopathy and myositis; and even provide insight into abnormal patterns of muscle activation. There is an essential role for the neurologist as well as for the specialist radiologist that requires a high level of familiarity of the various new types of image findings in this steadily advancing field.