Eccentric atherosclerotic plaques with positive remodelling have a pericardial distribution: a permissive role of epicardial fat? A three-dimensional intravascular ultrasound study of left anterior descending artery lesions.

AIMS: The transversal distribution of coronary atherosclerotic plaques (AP) (myocardial vs pericardial) affects vessel remodelling. The aim of this study was to define the impact of transversal lesion distribution on vessel remodelling in proximal and distal coronary segments using a 3D intravascular ultrasound (IVUS) reconstruction. METHODS: The study group included 70 lesions located in the left anterior descending artery within 5mm of the septal take-off, and imaged using 3D-IVUS. The take-off of the septal branch was used to divide the plaque into a myocardial and pericardial surface. The IVUS index of vessel remodelling was calculated as: [narrowest external elastic membrane (EEM) site cross-sectional area (CSA)-reference EEM CSA)/reference EEM CSAx100]. The lesions with an intermediate vessel remodelling index (between -25% and +15%) were excluded from analysis. RESULTS: Of the 38 APs with a pericardial distribution, 34 (89%) showed positive remodelling (P<0.001). The distal lesions had a positive vessel remodelling index regardless of transversal plaque distribution. At multivariate analysis, pericardial distribution and the distal location of AP were the only independent variables predictive of positive remodelling. CONCLUSIONS: The transversal distribution of atherosclerotic plaque affects vessel remodelling in left anterior descending coronary lesions, probably because of an extravascular splinting effect. Distal lesions usually show positive remodelling regardless of transversal plaque distribution.

Correlation between high frequency intravascular ultrasound and histomorphology in human coronary arteries.

OBJECTIVE: To test the efficacy of high frequency intravascular ultrasound (IVUS) transducers in identifying lipid/necrotic pools in atherosclerotic plaques. METHODS: 40 MHz transducers were used for in vitro IVUS assessment of 12 arterial segments (10 coronary and two carotid arteries, dissected from five different necropsy cases). IVUS acquisition was performed at 0.5 mm/s after ligature of the branching points to generate a closed system. Lipid/necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity. To obtain histopathological sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm long segments using the most distal recorded IVUS image as the starting reference. Samples were then fixed with 10% buffered formalin, processed for histopathological study, serially cut, and stained using the Movat pentacrome method. RESULTS: 122 sections were analysed. Lipid pools were observed by histology in 30 sections (25%). IVUS revealed the presence of lipid pools in 19 of these sections (16%; sensitivity 65%, specificity 95%). CONCLUSIONS: In vitro assessment of lipid/necrotic pools with high frequency transducers was achieved with good accuracy. This opens new perspectives for future IVUS characterisation of atherosclerotic plaques.

Intravascular ultrasound insights into plaque composition.

UNLABELLED: Previous studies correlating histomorphology with 20-30 MHz-derived intravascular ultrasound (IVUS) images showed that IVUS provides to some extent qualitative information on plaque composition. IVUS imaging proved to define calcifications with high sensitivity and specificity but was found to be less accurate in the assessment of soft components. Nevertheless previous studies on atherosclerotic plaque characterization were limited by use of low-frequency transducers that did not define accurately soft components. Our goal was to test the effectiveness of high frequency IVUS transducers in the identification of lipid/necrotic pools in atherosclerotic plaques. METHODS: Forty MHz transducers were used for in vitro IVUS assessment of 12 arterial segments (10 coronary arteries and 2 carotid arteries dissected from 5 different autopsy cases). IVUS acquisition was performed at a 0.5 mm/s speed after ligature of the branching points to generate a closed system. Lipid necrotic areas were defined by IVUS as large echolucent intraplaque areas surrounded by tissue with higher echodensity. To obtain histopathologic sections corresponding to IVUS cross sections, vessels were divided into consecutive 3 mm-long segments using the most distal recorded IVUS image as the starting reference. Then, samples were fixed with 10% buffered formalin, processed for histopathologic study, serially cut, and stained with the Movat penthacrome method. RESULTS: One hundred twenty-two sections were analyzed. Lipid pools were observed by histology in 30 cross sections (25%). IVUS revealed the presence of lipid pools in 19 of 122 cross sections with a sensitivity and specificity of 67% and 94%, respectively. CONCLUSIONS: High frequency transducers accurately identify lipid/necrotic pools and open new perspectives on future IVUS characterization of atherosclerotic plaques.

[ANP in the cirrhotic patient. A clinical contribution]. / L'ANP nel paziente cirrotico. Contributo clinico.

Pathogenesis of ascites in patients affected by liver cirrhosis is still debated; humoral and haemodynamic factors can play a role. Plasmatic renin activity (PRA), plasmatic aldosterone (PA), atrial natriuretic peptide (ANP) plasma levels, blood Na, K, urea, urinary K and Na were evaluated in 14 patients affected by liver cirrhosis (11 males and 3 females, aged from 38 to 62 years), 8 of them with ascites. The results were compared with those obtained in a control group poised to age and sex to the experimental group. 4 out of 14 patients suffering from ascites unresponsive to medical treatment were submitted to peritoneal venous jugular shunt (PVGS) and blood samples for PRA, PA and ANP were withdrawn immediately before, 4, 8 hours following surgery. The patients affected by liver cirrhosis without ascites showed PRA and PA levels similar to those observed in the control group, while ANP plasma levels were significantly higher (50.6 + 9.6 vs. 39.7 + 9.5 Pg/ml) (p < 0.02). In patients with ascites ANP, PA and PRA levels were higher than those observed in non ascites patients (ANP = 147.8 + 97.3 vs. 50.6 + 9.6 pg/ml; PA = 20.6 + 2.7 vs 7.8 + 0.8 ng/dl; PRA = 4.48 + 0.5 vs 1.9 + 0.34 ng/ml/h). In patients submitted to PVGS, PA and PRA levels were reduced 4 and 8 hours following the surgery, while ANP levels showed significant increase. A natriuretic and diuretic response has been observed even in the absence of ANP plasma levels variations.(ABSTRACT TRUNCATED AT 250 WORDS)