Objective-To test the eYcacy 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 diVerent 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% buVered 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. (Heart 2001;85:567-570) Keywords: intracoronary ultrasound; atherosclerosis; plaque morphology Coronary intravascular ultrasound (IVUS) provides quantitative information on lumen and vessel dimensions and plaque severity, as well as qualitative information on plaque composition in terms of hard and soft components and calcification. Previous IVUS studies on plaque composition, mainly performed in the early 1990s with 20-30 MHz transducers, showed that the technique defines calcification with high sensitivity and specificity, but is less accurate in assessing soft tissue components. [1][2][3][4][5][6][7][8][9] Thus, although 20 and 30 MHz transducers achieved appropriate definition of plaque morphology, the imaging of details such as the lipid pool and the fibrous cap remained poorly defined. No data are available on the characterisation of plaque morphology with high frequency transducers, which should allow more accurate definition of the soft components of the plaques.In this study we correlated corresponding IVUS and histopathological findings in human arterial specimens obtained at necropsy from patients with atherosclerosis, to determine how accurately 40 MHz IVUS can identify lipid/ necrotic pools. MethodsWe performed in vitro IVUS assessments, using continuous pull back, in arterial segments dissected from necropsy hearts. Arterial samples were serially sectioned in relation to IVUS markers. We then correlated the quantitative and qualitative evaluations of lipid/ necrotic pools obtained from histopathological slides with those obtained from IVUS cross sections. SAMPLE SERIESThe pathological series comprised 12 full length arteries, 10 coronary arteries (one left main, four left anterior...

Medical therapy often fails to control symptoms of severe heart failure. The possibility of modifying to some degree the global ventricular performance with the implantation of a physiological dual chamber pacemaker, set with a short atrioventricular delay (100 msec), has been adopted in two patients with severe heart failure due to coronary artery disease. The baseline clinical condition of both patients was characterized by leg edema, ascites, dyspnea at rest, or even orthopnea with a functional New York Heart Association (NYHA) class III-IV. Acute measurements of hemodynamic and echocardiographic parameters during stepwise shortening of AV interval guided the pacemaker implantation and setting of AV delay in the chronic phase. Within a few days after pacemaker implantation, both patients considerably improved their clinical status as well as their functional NYHA class, improving to class II in one patient and to class II-III in the other patient. In addition, modification of systolic and diastolic parameters paralleled these improvements functional class and clinical condition. Pacemaker therapy in severe heart failure refractory to medical therapy can be of considerable benefit in patients whose quality-of-life is severely compromised when pharmacological therapy is no longer effective. Acute hemodynamic and echocardiographic testing is useful in assessing the most appropriate AV delay and pacing mode.

Because the number of patients was relatively small, we could not use left ventricular mass regression after I year to distinguish among patients undergoing aortic valve replacement for aortic stenosis by means of valve prostheses with different hemodynamic performances.

Having a bileaflet aortic prosthesis of one size larger did not seem to significantly influence the pattern and the extent of regression of left ventricular hypertrophy after an intermediate period of follow-up.

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