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Endovascular ultrasound (US) elastography (EVE) was introduced to supplement endovascular US echograms in the assessment of vessel lesions and for endovascular therapy planning. Indeed, changes in the vascular tissue stiffness are characteristic of vessel wall pathologies and EVE appears as a very appropriate imaging technique to outline the elastic properties of vessel walls. Recently, a model-based approach was proposed to assess tissue motion in EVE. It specifically consists of a nonlinear minimization algorithm that was adapted to speckle motion estimation. Regarding the theoretical framework, such an approach considers the speckle as a material property; this assumption then led to the derivation of the optical flow equations, which were suitably combined with the Lagrangian speckle model estimator to provide the full 2-D polar strain tensor. In this study, the proposed algorithm was validated in vitro using a fresh excised human carotid artery. The experimental setup consisted of a cardiovascular imaging system (CVIS) US scanner, working with a 30-MHz mechanical rotating single-element transducer, a digital oscilloscope and a pressuring system. A sequence of radiofrequency (RF) images was collected while incrementally adjusting the intraluminal static pressure steps. The results showed the potential of this 2-D algorithm to characterize and to distinguish an atherosclerotic plaque from the normal vascular tissue. Namely, the geometry as well as some mechanical characteristics of the detected plaque were in good agreement with histology. The results also suggested that there might exist a range of intraluminal pressures for which plaque detectability is optimal.

We investigated the ability of 16-slice computer tomography (CT) to discriminate any restenosis after left main coronary artery stenting in 29 consecutive patients. CT was able to detect all stents and analyze the lumen properly in 27 of 29 cases. With the exception of arrhythmic or heavily calcified segments, multislice CT provides a noninvasive alternative to conventional coronary angiography in the follow-up of left main angioplasty with stenting.

Accurate understanding of the physiopathology of a coronary stenosis is a major objective in management during diagnostic coronary angiography. Measurement of fractional flow reserve (FFR) by coronary pressure measurement is a reliable method for evaluating the functional consequences of a lesion of the myocardium. This retrospective monocentric study of 114 patients showed that routine coronary pressure measurement for assessing the functional consequences of intermediate (30 to 70% stenosis) lesions or those of ambiguous topography: was necessary in 4% of diagnostic coronary angiographies enabling an immediate management decision. Using this method, 34% of complementary investigations were not performed (stress test, myocardial scintigraphy, dobutamine stress echocardiography). Seventeen per cent of unnecessary angioplasties were also avoided so that acute coronary event were also avoided when lesions with a FFR >0.75 were not treated by angioplasty. A 10-14% reduction in cost was achieved compared with a strategy of systematic angioplasty in respectively mono- or multivessel disease patients and 39% compared with performing ambulatory myocardial scintigraphy in patients with multivessel disease.

Intravascular ultrasound (IVUS) is known to be the reference tool for preoperative vessel lesion assessments and for endovascular therapy planning. Nevertheless, IVUS echograms only provide subjective information about vessel wall lesions. Since changes in the vascular tissue stiffness are characteristic of vessel pathologies, catheter-based endovascular ultrasound elastography (EVE) has been proposed in the literature as a method for outlining the elastic properties of vessel walls. In this paper, the Lagrangian Speckle Model Estimator (LSME) is formulated for investigations in EVE, i.e., using a polar coordinate system. The method was implemented through an adapted version of the Levenberg-Marquardt minimization algorithm, using the optical flow equations to compute the Jacobbian matrix. The theoretical framework was validated with simulated ultrasound rf data of mechanically complex vessel wall pathologies. The results, corroborated with Ansys finite element software, demonstrated the potential of EVE to provide useful information about the heterogeneous nature of atherosclerotic plaques.

Background: A 'thin' fibrous cap atheroma is the typical morphological characteristic of vulnerable plaque. Yet the very pathological studies that have provided these descriptions have also shown the actual prediction of plaque rupture to be rather less exact. Other relevant characteristics must be involved in the mechanisms of plaque rupture--blood pressure loading (P) and the material properties of the soft atheromatous core--as predictors of the distribution of the peak circumferential stress (PCS) locations., Methods and Results: We used a computational structural analysis based on three typical in-vivo intravascular ultrasound images of fibrous cap atheroma in which we decreased the cap thickness (CTh). With different soft atheromatous core Young's moduli (Ecore), 414 simulations were performed under eight different physiological loading blood pressures. The transition from plaque stability to plaque instability was defined by a threshold of 300 kPa and is a feature of vulnerability. It was found that (1) irrespective of plaque geometry and composition, CTh < 60 microm exposed the plaque to PCSs in excess of 300 kPa; (2) the exponential variations in PCS with change in CTh and Ecore values show that very slight structural changes are enough to tilt a vulnerable plaque from stability to instability or vice versa; and (3) the relationship between P and PCS is proportional with P acting as trigger or as protector., Conclusion: The present study shows why, in clinical practice, mere morphological detection by imaging techniques of thin-cap fibro-atheroma is not in itself enough for the prediction of future rupture., (Copyright 2004 Lippincott Williams & Wilkins)

The advance of cardiology has improved the prognosis of atherothrombosis through direct diagnosis and early management, but the global incidence of atherothrombotic events has been modified only slightly. Currently, although the stenosing effect of atherosclerosis is well known and if treated hardly poses a problem, the unpredictable risk of arterial thrombosis continues to cause the seriousness of the disease in as much as it is not linked to the degree of stenosis. The initiation of thrombosis progresses via destabilisation phenomena of atherosclerotic plaques with rupture or erosion of the capsule. The identification of plaques "at risk" of instability, so-called "vulnerable" plaques, is thus now a fundamental concept. Thanks to anatomo-pathology, certain morphological and functional criteria of these vulnerable plaques are better understood and are starting to find a clinical resonance. An inflammatory syndrome scenario, thin capsule, and a large lipidic heart associated with an as yet quiescent atherosclerotic plaque are predictive elements of acute coronary syndrome. These elements show promise and an already combined biological and morphological approach will certainly be at the heart of clinical research for years to come.

Quantitative angiography is a medical application where the user requires tools whose operational results in term of accuracy, precision, robustness and reliability must be extensively assessed and validated for clinical use. In this study, the 6sigma methodology has been applied to analyze the performances of the General Electric QA software method. In particular, the catheter calibration procedure was identified as the weakest function in term of sensitivity to procedure parameters, like point-spread-function, field-of-view, catheter dimensions. It was therefore improved by following a design for 6sigma scheme, and the main parameters that govern the QA accuracy and precision were put under quantifiable control.

The aim of this study was to assess the three coronary arteries systematically by endocoronary ultrasonography in patients with unstable angina to check the hypothesis of global destabilisation of atherosclerotic plaques in acute coronary syndromes (ACS). Sixty two coronary arteries were examined (2.6 per patient). Fifty plaque ruptures were diagnosed (2.08 per patient). Rupture of a plaque of the culprit lesion of the ACS was clearly detected in 9 patients (37.5%). At least one ruptured plaque on a site other than the culprit lesion was observed in 19 patients (79%), on another artery in 70.8% of cases and on two other arteries in 12.5% of cases. A complete endocoronary ultrasonic examination of the three coronary arteries in patients with a first ACS demonstrated that: multiple atherosclerotic plaque rupture may be detected by endocoronary ultrasonography; these multiple plaque ruptures occur simultaneously with the culprit lesion; they are frequent and can be situated on the three main coronary vessels and multiple plaque rupture other than the culprit lesion are less severe, non stenotic and less calcified. Thus, although a single lesion is clinically symptomatic, ACS seems to be associated with global coronary instability.

Coronary artery diseases are usually revealed using X-ray angiographies. Such images are complex to analyze because they provide a 2D projection of a 3D object. Medical diagnosis suffers from inter- and intra-clinician variability. Therefore, reliable software for the 3D reconstruction and labeling of the coronary tree is strongly desired. It requires the matching of the vessels in the different available angiograms, and an approach which identifies the arteries by their anatomical names is a way to solve this difficult problem. This paper focuses on the automatic labeling of the left coronary tree in X-ray angiography. Our approach is based on a 3D topological model, built from the 3D anthropomorphic phantom, Coronix. The phantom is projected under different angles of view to provide a data base of 2D topological models. On the other hand, the vessel skeleton is extracted from the patient's angiogram. The algorithm compares the skeleton with the 2D topological model which has the most similar vascular net shape. The method performs in a hierarchical manner, first labeling the main artery, then the sub-branches. It handles inter-individual anatomical variations, segmentation errors and image ambiguities. We tested the method on standard angiograms of Coronix and on clinical examinations of nine patients. We demonstrated successful scores of 90% correct labeling for the main arteries and 60% for the sub-branches. The method appears to be particularly efficient for the arteries in focus. It is therefore a very promising tool for the automatic 3D reconstruction of the coronary tree from monoplane temporal angiographic clinical sequences.

Background: Spontaneous rupture of atherosclerotic plaques is known to be involved in the mechanism leading to acute coronary syndromes. Means to detect plaques prone to rupture and predict rupture location would then be very valuable for clinical diagnosis., Design: In this study, finite element (FE) analysis based on intravascular ultrasound (IVUS) images of atherosclerotic arteries was used to predict in-vivo plaque rupture locations. In four patients with coronary artery diseases, IVUS images were recorded before and after balloon angioplasty. Pre-angioplasty images were recorded after injection of ATP. This caused a brief drop of arterial blood pressure down to values of about 20 mmHg, and thus allowed the recording of the unloaded configurations of arteries used to initiate FE analysis. Plaque rupture was triggered by balloon inflation (coronary angioplasty). FE simulations were performed under physiological loading conditions. Stress distributions within the plaque and the arterial wall were determined. The corresponding stress maps are presented., Results: Circumferential tensile peak stress areas were compared with plaque rupture locations on postangioplasty IVUS images. They were found to coincide in all four studied cases., Conclusion: Our results agreed with those reported in previous studies based on ex-vivo postnecropsic data and showed the feasibility of in-vivo prediction of atherosclerotic plaque rupture location.

High doses of heparin are recommended during coronary angioplasty although platelet inhibition seems to play a role in the prevention of ischaemic complications. Low dose heparin could reduce the incidence of local complications without increasing that of major coronary events. The authors report the results of a prospective register of coronary angioplasties performed by the femoral approach with a single bolus of 30 IU/Kg of heparin and immediate withdrawal of the 6 French introducer. Only patients with recent infarction or left main stem disease were excluded. All underwent clinical examination and ultrasonic scanning of the puncture site the day after the procedure. Four hundred and eighteen patients were included (mean age: 63.3 +/- 11 years; 79% men; 77% stenting). The average dose of heparin was 2253 +/- 1056 IU; the average procedure time was 25 +/- 16 minutes, and a final activated clotting time was 174 +/- 69 ms. The duration of normal compression was 7.7 +/- 3 min. Eighty-three point five per cent of patients were discharged the day after the procedure with a global cardiovascular complication rate of 2.87%. At 1 month, 1.67% of secondary cardiovascular events was recorded. Ultrasonography of the puncture site was abnormal in 7.6% of patients. Only one serious vascular complication (0.24%) requiring transfusion and surgical repair, was observed. The authors conclude that the use of low dose heparin appears effective and safe in cases without acute myocardial infarction. This protocol allows faster mobilisation and earlier hospital discharge of patients.

The mechanical function of a stent deployed in a damaged artery is to provide a metallic tubular mesh structure. The purpose of this study was to determine the exact mechanical characteristics of stents. In order to achieve this, we have used finite-element analysis to model two different type of stents: tubular stents (TS) and coil stents (CS). The two stents chosen for this modeling present the most extreme mechanical characteristics of the respective types. Seven mechanical properties were studied by mathematical modeling with determination of: (1) stent deployment pressure, (2) the intrinsic elastic recoil of the material used, (3) the resistance of the stent to external compressive forces, (4) the stent foreshortening, (5) the stent coverage area, (6) the stent flexibility, and (7) the stress maps. The pressure required for deployment of CS was significantly lower than that required for TS, over 2.8 times greater pressure was required for the tubular model. The elastic recoil of TS is higher than CS (5.4% and 2.6%, respectively). TS could be deformed by 10% at compressive pressures of between 0.7 and 1.3 atm whereas CS was only deformed at 0.2 and 0.7 atm. The degree of shortening observed increases with deployment diameter for TS. CS lengthen during deployment. The metal coverage area is two times greater for TS than for CS. The ratio between the stiffness of TS and that of CS varies from 2060 to 2858 depending on the direction in which the force is applied. TS are very rigid and CS are significantly more flexible. Stress mapping shows stress to be localized at link nodes. This series of finite-element analyses illustrates and quantifies the main mechanical characteristics of two different commonly used stents. In interventional cardiology, we need to understand their mechanisms of implantation and action.

The patients who have only single vessel disease of the right coronary artery have an excellent prognosis, unaffected by surgery. The object of this study was to evaluate the long-term prognosis of these patients after transluminal coronary angioplasty. The criteria of analysis were survival, anginal symptoms, quality of life and ergometric parameters. Two hundred and forty eight patients with an isolated lesion of the right coronary artery who underwent angioplasty were reassessed 39.6 +/- 22 months after angioplasty. The primary success rate was 89.9% with 5.2% of severe complications during the hospital period (myocardial infarction, bypass surgery, coronary angiography +/- angioplasty). The actuarial global and cardiac survival rates at 7 years were 88.4 and 96.2% respectively with no difference between the success and failure groups. The eight cardiovascular deaths and thirteen myocardial infarctions which were observed in the long-term were all in the successful angioplasty group. From the symptomatic viewpoint, 76% of the population became asymptomatic. The same results were observed in terms of quality of life with 58% of patients estimating it to be good in correlation with anginal status. The comparison of ergometric tests showed a significant gain in performance in 67% of patients. The authors conclude that the results suggest that angioplasty in single vessel disease of the right coronary artery provides a significant symptomatic and ergometric benefit but that it is impossible to assess the eventual benefits in terms of survival which would have needed a group of similar patients assessed under anti-ischaemic treatment and taking into consideration the recent innovations (stents, statins).

At the end of the 20th century, endocoronary ultrasonography has become established in many catheter laboratories. The information provided by this technique of invasive imaging has many qualitative and quantitative features. Is endocoronary ultrasonography a research or an everyday clinical tool to be used systematically or occasionally in routine procedures? Endocoronary ultrasonography is really a research tool because it is not redundant with conventional coronary angiography. Ultrasonography investigates the whole arterial wall. Its spatial resolution is twice that of angiography. Its contribution in this field in rich with many reports on arterial modelling, post-angioplasty remodelling, plaque rupture and atherothrombosis, the accurate description of the mechanical effects of angioplasty tools, two and three-dimensional quantification of atherosclerotic plaques and, finally, providing a very accurate biomechanical approach. Its use in routine procedures is only occasionally justified as there is no scientific proof in favour of a more widespread use with respect to changing the procedure or to evaluating patient prognosis. Endocoronary ultrasonography, a very rich technique, should be available in all catheter laboratories for occasional use. This technique is useful for all cardiologists performing coronary angioplasty by improving the evaluation of atheromatous plaques and countering the intrinsic ambiguities of coronary angioplasty.

Objective: To evaluate and compare in a double-blinded and prospective study the incidence of adverse reactions between two contrast agents used for coronary angiography and ventriculography. The first agent was the non-ionic, dimeric, isotonic contrast medium iodixanol (Visipaque), the other was the ionic dimeric contrast medium ioxaglate (Hexabrix)., Methods: A total of 110 consecutive patients were randomized and received either iodixanol 320 mgl/ml or ioxaglate 320 mgl/ml. The efficacy, safety, tolerability and specific cardiovascular effects were evaluated. Adverse reactions were recorded during the procedure and during the first 24 hours after the examination. Hemodynamic and electrophysiological parameters were recorded before and after the ventricular injection and the first injections into the left and right coronary artery, respectively., Results: The incidence of clinical adverse reactions was significantly different between iodixanol and ioxaglate (3% vs 28%, p = 0.0004). 24 patients (16 iodixanol; 8 ioxaglate) experienced no discomfort (sensation of warmth, coldness or pain), and the intensity of discomfort experienced by the remainder was similar for the two groups. No patient reported pain. During the 3 minutes after injection of contrast medium, the LV end-diastolic pressure increased but, apart from one reading, the increases with iodixanol were always significantly different (p < 0.05), and less than those for ioxaglate. During the same time period, heart rate was increased to a greater extent by ioxaglate (p < 0.05). QT interval was significantly (p < 0.05) prolonged with both ioxaglate and iodixanol, but the changes were less marked after iodixanol. The angiographic studies were of diagnostic quality for all patients and optimal diagnostic information was achieved in 92% of both groups., Conclusion: This randomized study shows that iodixanol and ioxaglate are of comparable diagnostic efficacy in coronary angiography and ventriculography, but that iodixanol is better tolerated by patients and results in less marked hemodynamic and eletrophysiological changes than does ioxaglate.

A model has been developed for estimating the geometric distortions in intravascular ultrasound (IVUS) imaging caused by the position of the ultrasound catheter within the artery. Geometric distortion causes degradation on cross-sectional images of the vessel wall where, for characteristic positioning of the transducer within the vessel, a circular artery is seen on IVUS images as a noncircular vessel represented by more or less complex shapes. Artefacts, therefore, have a clinical impact on the accuracy of qualitative and quantitative intravascular analyses. The main distortions are due to the inclination and the off-centered position of the transducer within the vessel. These effects are increased by two factors: first, the point of origin of the ultrasound beam does not coincide with the rotation axis of the catheter; second, in the case of a mechanical rotating transducer, the ultrasound beam is not perpendicular to the long axis of the catheter, but has an inclination such that the transducer looks forward from the emitting point. All these parameters are taken into account in the three-dimensional (3-D) geometric model developed in this paper. The model was formulated to predict the geometric deformation for artery contour of various shapes and can model artefacts during stent implantation (Finet et al. 1998). Simulations were made for various geometric configurations and compared to in vitro and in vivo IVUS images. The model results are consistent with the experimental results. Finally, the model was used for estimating the values of the geometric parameters that cause distortions on ultrasonic images.

Intravascular ultrasound imaging is able to provide direct images of the stent meshwork. However, a paradoxical question remains unanswered: Why is it not possible to correct or prevent implantation defects by ultrasound-guided implantation? We postulate that these discrepancies are due to image artifacts. We performed an in vitro experiment allowing detection, physical characterization, and computerized simulations of the various aspects of these artifacts. The width of the echo of a strut is variable, dependent on its distance from the transducer. The stent strut echo orientation is variable, and depends on the position of the transducer inside the stent. The stent contour image depends on the position of the transducer. In conclusion, knowledge of these stent intravascular ultrasound image artifacts enabled us to discriminate accurately between artifacts and real stent implantation defects, and are indispensable for accurate qualitative and quantitative analyses of stents.

Intravascular ultrasound (IVUS) imaging enables detailed analysis and precise measurements of vascular cross-sections. However, to achieve a reduction in the existing level of observer variability requires the development of quantitative IVUS. We have developed a fully automatic intraluminal edge detection technique, based on adaptive active contour models and called ADDER (adaptive damping dependent on echographic regions) that allows the quantitation of the intraluminal cross-sectional area (ICSA). Using a 30-MHz mechanically rotated transducer mounted at the tip of a 3.5-F catheter, 58 normal and pathologic arterial segments (from coronary, renal, splenic, iliac, and carotid arteries) were imaged in vitro. These images were analyzed by 2 experts, E1 and E2, who manually traced the intraluminal contour twice for each image, as well as with ADDER. Intra-observer variabilities for ICSAs were found to be excellent (-1.454 +/- 3.51% for E1, 0.96 +/- 5.4% for E2). The inter-observer variability was 2.1 +/- 4.3%. The success factor for ADDER was 89%. Its intra-observer variability was null, as the method always finds a unique contour. The correlation between the automatically detected ICSA and the manual ICSA was: r = 0.99 (y = 1.03x + 0.89 mm2). Morphometric variations between manually and automatically traced contours, analyzed by the centerline method, were 100 +/- 140 mm on average. In conclusion, the ADDER automatic contour detection applied to IVUS images is robust and characterized by small systematic and random errors; therefore, quantitative IVUS is a useful tool in clinical research trials.

Purpose: To assess the clinical feasibility of an experimental modified angiographic system capable of real-time digital stereofluoroscopy and stereography in X-ray angiography, using a twin-focus tube and a stereoscopic monitor., Methods: We report the experience obtained in 37 patients with a well-documented examination. The patients were examined for coronary angiography (11 cases), aortography (7 cases), pulmonary angiography (6 cases), inferior vena cava filter placement (2 cases), and cerebral angiography (11 cases). Six radiologists were asked to use stereoscopic features for fluoroscopy and angiography. A questionnaire was designed to record their subjective evaluation of stereoscopic image quality, ergonomics of the system, and its medical interest., Results: Stereofluoroscopy was successfully used in 25 of 37 cases; diplopia and/or ghost images were reported in 6 cases. It was helpful for aortic catheterization in 10 cases and for selective catheterization in 5 cases. In stereoangiography, depth was easily and accurately perceived in 27 of 37 cases; diplopia and/or ghost images were reported in 4 cases. A certain gain in the three-dimensional evaluation of the anatomy and relation between vessels and lesions was noted. As regards ergonomic considerations, polarized spectacles were not considered cumbersome. Visual fatigue and additional work were variously reported. Stereoshift tuning before X-ray acquisition was not judged to be a limiting factor., Conclusion: A twin-focus X-ray tube and a polarized shutter for stereoscopic display allowed effective real-time three-dimensional perception of angiographic images. Our clinical study suggests no clear medical interest for diagnostic examinations, but the field of interventional radiology needs to be investigated.

Background: The aim of this study was to elucidate whether beneficial effects of cardiomyoplasty (CMP) in patients with dilated cardiomyopathy are the result of a decrease in existing ventricular dilatation or a prevention of further dilatation., Methods and Results: Combined micromanometer-conductance catheters were used to evaluate left ventricular pressure-volume relationships in six patients with dilated cardiomyopathy before and at 6 and 12 months after CMP. Acute changes in preload and afterload were induced by a standardized leg-tilting intervention and a bolus infusion of nitroglycerin. After CMP, end-diastolic volume (EDV) decreased from 138+/-10 to 103+/-18 mL/m2 (P<.01) at 6 months and to 83+/-17 mL/m2 (P<.01) at 12 months. End-diastolic pressure (EDP) decreased from 20.2+/-6.4 to 13.9+/-7.7 mm Hg (P<.01) at 6 months after CMP. Peak ejection rate and ejection fraction increased at 6 months after CMP from 594+/-214 to 799+/-214 mL/s (P<.05) and from 26.6+/-4.7% to 40.1+/-8.3% (P<.05), respectively. Peak dP/dt decreased at 12 months after CMP from -842+/-142 to -712+/-168 mm Hg/s (P<.05). Leg-tilting before CMP increased EDP from 20.2+/-6.4 to 25.6+/-5.2 mm Hg (P<.01), end-systolic pressure (ESP) from 118+/-17 to 122+/-17 mm Hg (P<.05), and tau from 50.8+/-2.8 to 53.8+/-2.3 ms (P<.05). Six months after CMP, leg-tilting also increased EDV from 103+/-18 to 110+/-22 mL/m2 (P<.05) and ESV from 62+/-14 to 66+/-14 mL/m2 (P<.05). Before CMP, nitroglycerin decreased EDP from 20.2+/-6.4 to 10.4+/-3.8 mm Hg (P<.01), ESP from 118+/-17 to 96+/-11 mm Hg (P<.05), ESV from 100+/-11 to 89+/-7 mL/m2 (P<.05), and tau from 50.8+/-2.8 to 44.5+/-3.7 ms (P<.05). Six months after CMP, nitroglycerin decreased EDP, ESP, and tau to similar values., Conclusions: Our findings show that up to 1 year after CMP, marked decreases in left ventricular volume are present. Our measurements suggest that CMP actively reduced the dilated ventricle but did not prevent a higher EDV on an increased venous return. The latissimus dorsi muscle wrap contraction results in better synchronization of contraction and more rapid emptying of the left ventricle.

The article presents a case of subacute coronary artery thrombosis investigated by classic methods, coronary angiography, and MRI. T1- and T2-weighted images showed high signal intensity within the lumen of the right coronary artery corresponding to the methemoglobin content of the thrombus. Dynamic sequence images with intravenous gadolinium contrast agent displayed lack of right coronary artery enhancement, confirming coronary occlusion. The coronarography revealed the same finding. MRI appears to be a promising method of coronary thrombosis assessment.

Arterial lumen volume, determined by sequential coronary angiography, could have advantages over more commonly used variables (such as percent stenosis or minimal lumen diameter) as a primary endpoint in clinical trials evaluating post-angioplasty restenosis or atherosclerotic plaque progression. We validated a quantitative coronary angiography analysis (QCA) system aimed at measuring lumen volume from coronary angiography films by a densitometric method. Using images of polyacrylate models filled with different concentrations of contrast medium, accuracy (mean of the differences between known and measured values of a measurement) and precision (standard deviation of the difference) were lower than or equal to 0.09 and 0.21 mm, respectively, for diameters ranging from 1.5 to 16 mm. In terms of volume measurement, accuracy was 30.2 mm3 and precision 5.7 mm3 for a known volume of 620.2 mm3. To assess the short-term variations of lumen volume measurements under conditions resembling those encountered in clinical trials, a special image comparison program of the QCA system was used to measure the same coronary artery segment on two images taken 10 minutes apart in 21 patients. The mean difference between the two measurements was 1.7 +/- 12.4 mm3, with a coefficient of variation of 15%. An error of +/-2 frames in the selection of images to be analyzed had little influence on the results. We conclude that the QCA system provides easy-to-achieve standardization of the image acquisition process and sufficient reproducibility for repeated measurement of volume of a coronary artery segment, which can serve as the primary endpoint in clinical trials evaluating atherosclerotic plaque progression or restenosis after angioplasty.

Background: Nitric oxide (NO) donors, in addition to their vasodilator effect, decrease platelet aggregation and inhibit vascular smooth muscle cell proliferation. These actions could have beneficial effects on restenosis after coronary balloon angioplasty., Methods and Results: In a prospective multicenter, randomized trial, 700 stable coronary patients scheduled for angioplasty received direct NO donors (infusion of linsidomine followed by oral molsidomine) or oral diltiazem. Treatment was started before angioplasty and continued until 12 to 24 hours before follow-up angiography at 6 months. The primary study end point was minimal lumen diameter, assessed by quantitative coronary angiography, 6 months after balloon angioplasty. Clinical variables were well matched in both groups. However, despite intracoronary administration of isosorbide dinitrate, the reference diameter in the NO donor group was significantly greater than in the diltiazem group on the preangioplasty, postangioplasty, and follow-up angiograms. Pretreatment with an NO donor was associated with a modest improvement in the immediate angiographic result compared with pretreatment with diltiazem (minimum luminal diameter, 1.94 versus 1.81 mm; P = .001); this improvement was maintained at the 6-month angiographic follow-up (minimal lumen diameter, 1.54 versus 1.38 mm; P = .007). The extent of late luminal narrowing did not differ significantly between groups (loss index in the NO donor and diltiazam groups, 0.35 +/- 0.78 and 0.46 +/- 0.74, respectively; P = .103). Restenosis, defined as a binary variable (> or = 50% stenosis), occurred less often in the NO donor group (38.0% versus 46.5%; P = .026). Combined major clinical events (death, nonfatal myocardial infarction, and coronary revascularization) were similar in the two groups (32.2% versus 32.4%)., Conclusions: Treatment with linsidomine and molsidomine was associated with a modest improvement in the long-term angiographic result after angioplasty but had no effect on clinical outcome. The improved angiographic result related predominantly to a better immediate procedural result, because late luminal loss did not differ significantly between groups.

Intravascular ultrasound enables detection of the components of atherosclerotic plaques. The diagnostic value was assessed by ROC (receiver operating characteristic) curves on images acquired in vitro and correlated with the histological findings in 61 arteries. Five questions were asked of each operator; the reply was represented by a continuous variable in order to express all nuances of judgement. The area under the ROC curve, Az, was the criterion of performance (0.5 : chance response : 1.0 : all replies were accurate). Detection of plaque was satisfactory (Az = 0.89). The three layer appearance of muscular arteries was well recognised (Az = 0.94). The fibrous composition of a plaque was only just satisfactory (Az = 0.88) with 38.7% interindividual variability. The lipid composition of the plaque was poorly recognised (Az = 0.76) with large interindividual variability (52.8%) : hypoechogenicity was too ambiguous a sign from the acoustic point of view. A hypoechogenic zone must not be synonymous with a lipid plaque but a cellular zone. Calcium can almost always be detected (Az = 0.98) with a very low interindividual variability (10.7%), fibrohyaline progression of some plaques can be confusing. The authors present a more objective description of endovascular ultrasonographic images. They conclude that the diagnostic performance of 30 MHz intravascular ultrasound is satisfactory but several limitations are apparent in the interpretation of images, especially hypoechogenic zone and hyper-reflective zones with high attenuation.

The intravascular ultrasound image of the intraluminal contour depends on the difference between acoustic impedances of the media which create the endoluminal interface. There are several limitations to the visualization and detection of this interface. These limitations are due to artifacts encountered during image formation and to anatomical complexity. The purpose of this study is to obtain intraluminal contour enhancement using ultrasound contrast agent (UCA). Therefore, our objective was to address the feasibility of this technique by documenting the following: (i) the acoustic properties of UCA at 30 MHz; (ii) in vitro experimentation with tube or postnecrotic artery; and (iii) suitable digital processing. The images obtained with UCA (enhanced image quality) and subtracted from those without UCA provided, after simple digital processing, accurate visualization of the arterial lumen. The image obtained exhibits an even, high-contrast intraluminal edge. Such characteristics facilitate contour extraction by the automated contour detection procedures.

The limited resolution of any imaging system causes edge blurring of objects acquired with X-ray. In digital angiography, this effect combined with noise gives rise to systematic and random errors in the determination of vessel dimensions. The influence of bandwidth limitation on the estimation of tube diameter is established by a theoretical approach: it leads to over and underestimations of catheter and vessel diameter dimensions. Therefore a correction is proposed that counterbalances the point spread function (PSF) offset. The residual inaccuracy and the variability of measurement of phantom tubes are analyzed and evaluated in controlled conditions. Some of the parameters which govern their extent are identified: field-of-view, catheter size, concentration of contrast agent.

A coronary angiographic view is said to be "optimal" when the directing radius of the X-ray beam is perpendicular to the long axis of a stenosis. The object was to fulfill two criteria: 1) the accurate calculation of the spatial orientation of the stenosis to obtain the optimal position, 2) rapid and optimal positioning of the angiographic material with easy rotation around the axis of the stenosis. Two combined solutions were proposed:the Advantx L/C (GE Medical systems) angiocardiographic system with three motorised axes of rotation and a specific software. This software takes into account two longitudinal axes of the stenosis traced by the operator in two conventional incidences and then determines the angles of optimal positioning (accuracy +/-5 degrees). During 97 consecutive coronary angiograms, the software was used in 23 cases (24%) and judged to be useful in 16 cases (70%). In 2 of the 23 cases (8%) the mechanical angles calculated could not be used, the incidences being incompatible with the patient's position. During the angiograms, the best two images of stenosis (one conventional, one optimal) were retained to form a pair of images. Eight observers analysed 37 pairs of images shown side by side. 65% of the images selected from each pair as being the best descriptive appearance of the stenosis came from the optimised system. During quantitative analysis, only the length of stenosis differed statistically between the two modes of acquisition (1.26 +/- 0.36 mm; p = 0.0014). This system is useful during coronary angiography for providing optimal views of stenosis free from any geometric distorsion and without superimposition of adjacent branches.

Rationale and Objectives: For determining the optimum angulations of the x-ray beam with respect to the vascular morphology of a given patient, the authors present a solution combining a single-plane angiographic system and a dedicated procedure., Methods: The clinical evaluation of the vessel profiling acquisitions focuses on qualitative appraisal and quantitative analysis of conventional and optimum projections., Results: The qualitative evaluation demonstrates the pitfall for an operator to discern optimum from conventional projections. The 70% of preferences for vessel profiling bear witness to the constraints imposed occasionally by the optimum angulations, which may be impracticable for various reasons. However, vessel profiling yields lesions inspection at an optimum view, free of geometric foreshortening. Moreover, there is less risk of superimposition with other branches. From a quantitative standpoint, vessel profiling unveils the lesion with a length significantly longer than in conventional view., Conclusions: Vessel profiling offers a qualitative optimization of angiographic images and more exact quantitative analysis.

From January 1990 to June 1994, 240 patients (mean age, 60 +/- 10 years) underwent myocardial revascularization with the exclusive use of in situ bilateral internal mammary and right gastroepiploic arteries. Left ventricular function was normal in 34% of patients, moderately impaired in 58.5%, and severely impaired in 7.5%. The mean number of distal anastomoses was 3.5 +/- 0.7 and the rate of complete myocardial revascularization was 80%. Early mortality was 0.4%, and complications occurred in 20 patients: myocardial infarction, 1.6%; intraaortic balloon pump, 0.8%; reoperation for bleeding, 0.8%; and mediastinitis, 0.4%. Early (15th postoperative day) angiographic control of grafts was performed in 51 patients; the rate of functional and patent anastomoses was 100% for internal mammary arteries and 96% for gastroepiploic arteries. Early functional results (3 +/- 1 postoperative months) were studied in 141 patients during exercise test with medical treatment: 99% were symptom-free and 14% had ischemic modification of electrocardiograms. A 2-year postoperative functional assessment without medical treatment was performed during exercise test in 66 patients: 98% were symptom-free and 26% had ischemic modification of electrocardiograms; during the same procedure, thallium myocardial scintigraphy was obtained in 50 patients and 18 patients had moderate ischemic defect on exercise. Ischemic modifications of electrocardiograms and defects seen on thallium scintigraphy were correlated significantly with incomplete revascularization (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Background: Since the clinical introduction of dynamic cardiomyoplasty, a discrepancy has been observed between unchanged measurements of cardiac function and improved clinical outcome., Methods and Results: We performed a beat-to-beat analysis of cardiac performance at rest in nine cardiomyoplasty patients 6 to 24 months after operation. Conductance and micromanometer catheters were placed in left ventricle and aorta and used for measurements over a 15-second period, during which the wrapped latissimus dorsi (LD) muscle was stimulated for 10 seconds in a 1:2 synchronization mode followed by a 5-second period without LD stimulation. The synchronization delay between start of the QRS complex and the LD contraction was changed from 4 up to 125 ms at the patient's clinical stimulation strength and at an increased supramaximal amplitude. Comparing the LD assisted period to the unassisted period, at the clinical settings no significant changes in stroke volume (SV) as measured by the conductance technique and the aortic Modelflow technique were observed. A significant (P < .05) rise in left ventricular end-diastolic pressure (LVEDP) was observed directly after the assisted 10-second period. The peak ejection rate (PER) of left ventricular volume increased (P < .05), with a mean of 28 +/- 23% during the LD stimulated beats. At the patient's individual best setting, SV of the stimulated beats increased (P < .01) by a mean of 20 +/- 15%. Systolic aortic pressure increased (P < .01) by a mean of 7 mm Hg, peak negative dP/dt increased (P < .01), and PER increased, with a mean of 68 +/- 24% (P < .01). LVEDP was similar in stimulated and unstimulated beats and increased (P < .05) in the nonpaced 5-second period. The delay for the best setting ranged from 25 to 125 ms; the stimulus strength was 1.5 to 3 V higher than the clinical setting. At the patient's individual worst setting, SV remained unchanged and PER was higher, with a mean of 30 +/- 25% (P < .05). The worst setting was observed at the 1.5- to 3-V-higher stimulus strength; in six patients, it was at a short delay (4 to 25 ms) and in three patients, at the longest delay (100 to 125 ms)., Conclusions: By the left ventricular conductance catheter and aortic Modelflow methods, improvement in cardiac function by dynamic cardiomyoplasty was demonstrated in this patient group. The synchronization interval, stimulus strength, and stimulus duration appeared to be critical for obtaining optimal improvement.

Between November 1989 and September 1990, a cardiomyoplasty procedure was performed in 12 male patients with a mean age of 59 years. All patients were in New York Heart Association class III. Reinforcement cardiomyoplasty was isolated in 4 patients and associated with a cardiac procedure in 8. There were no perioperative deaths. Failure of cardiomyoplasty occurred in 5 patients because of recurrence of disabling congestive heart failure: 3 patients died late, and 2 had heart transplantation. The actuarial survival rate was 83% at 1 year and 73% at 2 years. Hemodynamic studies were done preoperatively in all patients, at 6 months postoperatively in 11 patients, at 1 year in 8, and at 2 years in 7. At the 2-year follow-up, 6 of the 7 survivors who did not have transplantation were functionally improved with reduced medical treatment. The following indices improved significantly at the 2-year evaluation compared with baseline: exercise capacity (63 +/- 13 W versus 83 +/- 17 W); left ventricular (LV) end-diastolic pressure (20 +/- 7 mm Hg versus 11 +/- 5 mm Hg); and angiographic LV ejection fraction (0.25 +/- 0.09 versus 0.40 +/- 0.15). Pulmonary artery pressure, pulmonary capillary wedge pressure, and cardiac index remained unchanged. Four patients underwent beat-to-beat analysis of LV function at 2 years; during skeletal muscle stimulation, stroke volume increased by 7% to 35% and LV end-systolic pressure, by 5% to 9%. In the 5 patients with failed cardiomyoplasty, mean pulmonary artery pressure and LV end-diastolic volume were higher preoperatively than in the 7 survivors.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravascular ultrasound catheters provide cross-sectional images of vessel walls and surrounding tissues with rotating transducers, and the behavior of ultrasound in heterogeneous media both cause degradation of image quality. Qualitative and quantitative analyses of in vivo studies are operator-dependent and limited by artifacts. We investigated these limitations by an in vitro study on plexiglass phantoms and segments of fresh arteries. We observed, analyzed and interpreted the most specific reasons for image artifacts: geometric distortions, the point spread function of the imaging system and the near field effects. Various practical implications have resulted from this study. Knowledge of the most obvious pitfalls will enable the user to obtain maximum benefits from intravascular ultrasound imaging, and to appreciate its limitations.

Intravascular ultrasound is a new method of visualizing details of vascular pathology, providing (real time) high resolution images of vascular walls. Most of the research on the technique has explored its qualitative and quantitative capabilities to improve the assessment of atherosclerotic vascular disease in vivo. Intravascular ultrasound differs from angiography and angioscopy in its ability to penetrate below the surface of the vessel lumen, demonstrating specific appearances of the distribution and composition of plaque. Image analysis is operator dependent. Although this technology is very promising limitations such as artefacts and loss of image quality in heavily calcified vessels hinder its use. There is hope that this imaging technique may ultimately improve the results of endovascular interventions.

The ability of an intravascular ultrasound catheter to give cross-sectional images of vessel walls and surrounding tissues, and the behavior of ultrasound in heterogeneous media, are at the origin of degradation of image quality. Qualitative and quantitative analyses of in vivo studies are then operator-dependent and are limited by artifacts. We investigated these limitations by an in vitro study on plexiglass phantoms and segments of fresh arteries. We used a 20 MHz transducer mounted on the tip of a 4.8 F catheter and an interventional ultrasound system. The ultrasound beam is reflected onto the rotating transducer at 600 rotations per minute (RPM), creating 360 degrees real-time images (10 images/second). We then observed, analyzed and interpreted the most specific reasons for image artifacts: geometric distortions, multiple echoes, the point spread function (PSF) of the imaging system, near-field effects, "petal-shaped" effect, and ultrasound speckle. Various practical implications have resulted from this study. Only a thorough knowledge of how to avoid some of the most obvious pitfalls will enable the user to obtain maximum benefits from intravascular ultrasound imaging, and to appreciate its limitations.

Congenital atrial diverticula are rare, especially those involving the right atrium. This condition was observed in a 52 year old man who presented with palpitations. The diagnosis was made by two-dimensional echocardiography and confirmed by CT scan, magnetic resonance imaging and angiography. In the absence of significant invalidity, no treatment was recommended. Only three other cases of this condition have been previously reported, all of which were referred for surgery for thrombotic complications, arrhythmias and cardiac failure. Anatomo-pathological analysis showed different appearances: fibrous tissue and lipomatous degeneration. In the absence of associated heart disease, these aneurysms are probably congenital.

The evaluation of the impact of therapy on the evolution of atherosclerotic lesions or restenosis after angioplasty requires the use of techniques of vascular imaging. The reference invasive method is digital angiography although it does not provide data on the arterial wall thickness. This parameter can be approached however by intravascular ultrasound imaging, a technique which has a number of important practical limitations. Of the non-invasive techniques available, Doppler ultrasonography is the only one that can be used in clinical trials. Nuclear magnetic resonance imaging is the object of much research and is without doubt the technique of the future. The choice of model of atherosclerosis influences that of the imaging technique: cineangiography for coronary arteries, digital angiography or Doppler ultra sonography for lower limb arteries and Doppler ultrasonography for the carotid arteries. Interpretation of angiography is now performed quantitatively by videodensitometry. Interpretation of other techniques should be performed by a second independent observer and "blinded" with respect to the order in which the investigations were performed and to the treatment administered. The criteria of judgment may be qualitative (progression, stabilisation, regression) or quantitative, the latter having a number of advantages over the former. Of the quantitative criteria, the percentage stenosis, though widely used, does not fully answer the question posed, and neither does the diameter of the stenosis. The volume of the arterial lumen calculated from videodensitometric data would seem to be the best, by its sensitivity and additivity, current angiographic parameter.(ABSTRACT TRUNCATED AT 250 WORDS)

We present a case of herniation of the left atrial appendage through a congenital partial absence of the pericardium. The diagnosis was demonstrated by echocardiography and the surgical correction achieved with autologous pericardium.

We evaluated myocardial protection with Hamburg oxygenated crystalloid cardioplegic solution in a double study. Part I was a prospective metabolic study, measuring myocardial adenosine triphosphate (ATP) and creatine phosphate (CP) contents before and after ischemia in 30 coronary bypass (CABG) patients. During ischemia, CP levels decreased significantly, whereas ATP did not. After 10 minute of reperfusion, mean ATP contents were 90% of preischemic values and CP levels increased to 85% of preischemic values. Spontaneous myocardial defibrillation was seen in 93.3% of patients. Part II included evaluation of early postischemic myocardial function in 228 patients, 48 with multiple valve replacement (MUVR) and 180 with CABG. Spontaneous myocardial defibrillation was seen in 90.3%. Cardiac index, measured before and 1 and 12 hours after surgery, increased significantly in the postischemic period (from 1.95 +/- 0.9 to 2.5 +/- 0.7 l/min m2 in MUVR, p 0.04; from 2.2 +/- 0.6 to 2.7 +/- 0.7 l/min/m2 in CABG, p 0.01). Myocardial infarction frequency was 3% among CABG patients, and unrelated to the number of distal anastomosis or to aortic cross-clamp time. Early postoperative mortality was 6.2% for MUVR and 0.5% for CABG. Thus, oxygenated cardioplegia with Hamburg solution preserves high-energy phosphate compounds and prevents ischemic injury, with excellent short-term clinical results.

The natural history of the complications of coronary heart disease has been defined by anatomicopathological and epidemiological studies, particularly the Framingham study. At the same time, research is being carried out on risk factors which play a role in the progressive development of atheromatous plaque (atherogenic factors: hypertension: hypercholesterolaemia) and those factors which lead to complications in the atheromatous plaque (aggravating or precipitating factors: smoking, thrombosis, etc.). This schematic perspective may lead to the redefinition of the strategy to adopt in fighting atherosclerotic arterial disease; a better aim will thus the taken in the fight against hypercholesterolaemia.

The purpose of this study was to determine precisely which additional information on survival at 1 year and 4 years was provided by an ambulatory 24-hour ECG recording performed 3 weeks after myocardial infarction (MI), compared to clinical data. The study was conducted in 107 consecutive patients under 75 years of age who had had MI and were followed up for a mean period of 4 years and 9 months. The clinical variables most closely associated with mortality at both 1 year and 4 years were those which reflected the severity of myocardial damage and left ventricular dysfunction before or during hospitalization, viz.: a history of MI or heart failure (HF), HF in the acute phase, and digitalis-diuretic treatment on discharge. At 4 years a multivariate analysis yielded 3 separate clinical variables which enabled cardiac mortality to be predicted: history of MI (p less than 0.001), presence of HF in the acute phase (p less than 0.001) and history of hypertension (p less than 0.02). Ventricular arrhythmias also were closely associated with mortality, but only during the first year, the 2 most discriminant factors being a mean hourly frequency of ventricular ectopic beats (VEB) greater than 10, and the presence of successive VEB (doublet or burst of ventricular tachycardia). The positive predictive values (PPV) of clinical and ambulatory ECG recording variables taken separately for mortality at 1 year were fairly similar (about one-third) as regards HF in the acute phase, history of MI, successive VEB and mean VEB frequency greater than 10/h, the corresponding risk ratios being 23.9, 13.7, 11.6 and 9.4 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Between August, 1974 and May, 1987, 486 patients were treated for infective endocarditis. In 16 of these patients (12 men, 4 women, mean age 44.3 +/- 18.0 years at the time of the first episode) the endocarditis recurred: once in 14 patients, twice in 2 patients. The time elapsed between recovery from the first episode and onset of the recurrence varied from 6 to 159 months (mean 54.3 +/- 35.1 months). Among the 18 recurrences, 10 affected native valves (mitral 6, aortic 4) and 8 aortic prostheses. In all but one case the organism isolated during the recurrence (Streptococcus in 14 cases, Staphylococcus in 3 cases, Rickettsia in 1 case) was different from the organism responsible for the previous infection. The 16 patients were followed up for periods of 28 to 203 months (mean 107.0 +/- 58.0 months), counting from the onset of the first episode. Ten patients were treated medically during the second episode: 4 died and 2 had a second recurrence, lethal in one of them (time elapsed between the onset of the first episode and the date of death: 32 to 149 months). Six patients were operated upon (valve replacement in 5 cases, closure of a left aorto-ventricular fistula in 1 case) without deaths. Nine of the 11 survivors are now asymptomatic. The actuarial survival rate in recurrent endocarditis (75 p. 100, 10 years after the onset of the first episode) is not different from that observed in non-recurrent endocarditis.

Although Q wave and non-Q wave MI are often referred to as "transmural" and "nontransmural," there is no anatomic evidence to justify this distinction. Nevertheless, a distinction is important, because the two entities have a different prognosis. At the present time, between 25% and 35% of MIs are non-Q wave. They are frequently observed in patients with previous coronary events. They occur in a relatively older population and involve a slightly higher proportion of women than do Q wave MIs. The degree of cardiac damage is less, reflected by a smaller rise in enzyme level and less impairment of left ventricular ejection fraction; early reperfusion may occur, after spontaneous thrombolysis or resolution of coronary spasm. The immediate mortality rate is half that of Q wave MI but identical in the long term. Reinfarction and angina are more frequent because of a peri-infarction zone of ischemia maintained by a high-grade coronary stenosis and inadequate collateral circulation. Early characterization of those MIs likely to progress is important. Diltiazem seems effective in this context if given between 24 and 72 hours of the onset of the event. Other therapeutic approaches need further assessment.