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Biomedical subjects

C Di Mario

Publications and source records attributed to C Di Mario.

At least 127 records · Page 7Linked to original sources
PubMed1996

Optimized expansion of the Wallstent compared with the Palmaz-Schatz stent: on-line observations with two- and three-dimensional intracoronary ultrasound after angiographic guidance.

Optimized stent expansion by high-pressure inflations of oversized balloons has initially been derived from experience obtained with the Palmaz-Schatz stent, whereas there is little experience with this strategy in the Wallstent. By using this approach with quantitative coronary angiographic guidance, 20 Wallstents and 20 Palmaz-Schatz stents were implanted in 34 patients and consecutively examined by conventional two-dimensional (2D) intracoronary ultrasound (ICUS) and three-dimensional (3D) ICUS on the basis of the application of a pattern recognition algorithm. Ultrasound criteria of adequate stent expansion were defined as a complete apposition of the stent to the vessel wall, a stent symmetry index (SSI = minimum/maximum lumen diameter) > or = O.7, and a stent-reference lumen area ratio (SRR = Minimum intrastent lumen area/Average of proximal and distal reference lumen area) > or = O.8. In all cases a smooth angiographic lumen and a negative diameter stenosis, on the basis of a distal reference, was achieved. For the Wallstents ICUS showed a higher SSI (2D, 0.95 +/- 0.04 vs 0.85 +/- 0.09; p < 0.001; 3D, 0.90 +/- 0.09 vs 0.82 +/- 0.11, p < 0.05) and a lower SRR (2D, 0.66 +/- 0.12 vs 0.81 +/- 0.13, p < 0.005; 3D, 0.63 +/- 0.14 vs 0.74 +/- 0.15, p < 0.05) than for the Palmaz-Schatz stents. Ninety percent of failure in meeting these criteria resulted from a low SRR. The incidence of incomplete stent apposition (one in both stents) or SSI <0.7 was low and generally associated with an SRR <0.8. The Wallstents met the ICUS criteria less often (2D, 2(1O%) vs 10(50%), p < 0.01; 3D, 3(15%) vs 9(45%), p < 0.05), were significantly longer (35.1 +/- 7.7 mm and 14.3 +/- 3.3 mm, p < 0.0001), and generally demonstrated a larger vessel tapering, measured as proximal minus distal ICUS reference lumen area (1.33 +/- 2.91 mm2 vs 0.44 +/- 1.97 mm(2), not significant). Wallstents meeting the ICUS criteria, however, showed less vessel tapering (0.18 +/- 1.64 mm(2)). Thus optimized stent expansion was followed by excellent angiographic results for both Palmaz-Schatz and Wallstent. Although angiographic results and visual assessment of the ICUS examination suggested a good outcome, few Wallstents met the ICUS criteria in contrast to the Palmaz-Schatz stents. The low value of the SRR in the Wallstents is likely to be caused by vessel tapering, suggesting that this criterion may be unsuitable in assessing the adequacy of the expansion of relatively long stents such as the Wallstent.

Aged↗
PubMed1996

Morphometric analysis in three-dimensional intracoronary ultrasound: an in vitro and in vivo study performed with a novel system for the contour detection of lumen and plaque.

Currently, automated systems for quantitative analysis by intracoronary ultrasound (ICUS) are restricted to the detection of the lumen. The aim of this study was to determine the accuracy and reproducibility of a new semiautomated contour detection method, providing off-line identification of the intimal leading edge and external contour of the vessel in three-dimensional ICUS. The system allows cross-sectional and volumetric quantification of lumen and of plaque. It applies a minimum-cost algorithm and the concept that edge points derived from previously detected longitudinal contours guide and facilitate the contour detection in the cross-sectional images. A tubular phantom with segments of various luminal dimensions was examined in vitro during five catheter pull-backs (1 mm/sec), and subsequently 20 diseased human coronary arteries were studied in vivo with 2.9F 30 MHz mechanical ultrasound catheters (200 images per 20 mm segment). The ICUS measurements of phantom lumen area and volume revealed a high correlation with the true phantom areas and volumes (r = 0.99); relative mean differences were -0.65% to 3.86% for the areas and 0.25% to 1.72% for the volumes of the various segments. Intraob-server and interobserver comparisons showed high correlations (r = 0.95 to 0.98 for area and r = 0.99 for volume) and small mean relative differences (-0.87% to 1.08%), with SD of lumen, plaque, and total vessel measurements not exceeding 7.28%, 10.81%, and 4.44% (area) and 2.66%, 2.81%, and 0.67% (volume), respectively. Thus the proposed analysis system provided accurate measurements of phantom dimensions and can be used to perform highly reproducible area and volume measurements in three-dimensional ICUS in vivo.

Algorithms↗
PubMed1996

Three-dimensional intracoronary ultrasound imaging. Methodology and clinical relevance for the assessment of coronary arteries and bypass grafts.

Three-dimensional (3-D) reconstruction of intracoronary ultrasound (ICUS) images has an increasing application as the applicability of systems of on-line analysis provides a superior guidance by coupling the advantages of a high-resolution cross-sectional imaging with an overview of stenosis and reference segments. Detection of the external contour of the vessel which is a prerequisite for measurements of coronary plaques is currently not provided by the algorithms for automated on-line analysis. Thus, off-line reconstruction is required for studies aiming at the assessment of progression/regression of atherosclerosis and of mechanisms of interventions or restenosis. Various 3-D reconstruction methods with specific advantages and limitations are able to meet the different requirements concerning applicability, quality of visualization, and accuracy of quantification. The use of 3-D ICUS in the assessment of cardiac transplant recipients permits a more reliable and accurate quantification of intimal hyperplasia as seen in cardiac allograft arteriopathy. In patients undergoing bypass surgery it may influence the therapeutic decision, since it allows to determine the longitudinal extent of calcification and frequently discovers atherosclerosis in angiographically normal segments. Vessel stenoses both of native coronary arteries and bypass grafts can be studied by 3-D ICUS and additional information can be obtained during catheter based interventions. Despite some remaining technical limitation 3-D reconstruction of ICUS images has the potential of becoming a practical tool to simplify the interpretation and quantification of ICUS images.

Algorithms↗
PubMed1995

Intracoronary heparin delivery in humans. Acute feasibility and long-term results.

BACKGROUND: Inefficacy of systemic drug administration for restenosis prevention may partially relate to insufficient local drug concentration. This study aimed to evaluate the acute feasibility and long-term outcome of using an infusion-perfusion coil balloon, Dispatch. METHODS AND RESULTS: In 22 patients after balloon angioplasty, the coil balloon was studied for (1) feasibility of local heparin delivery, (2) symptoms and signs of ischemia during prolonged deployment compared with angioplasty balloon occlusion, (3) coronary pressure and flow distal to the inflated device, and (4) long-term clinical and angiographic results. During prolonged intracoronary deployment of the coil balloon (29 +/- 8 minutes), 5 of 22 patients developed mild chest pain versus 20 of 22 during angioplasty (275 +/- 283 seconds). Neither hemodynamic nor vectorcardiographic signs of ischemia were detected, in contrast to angioplasty balloon occlusion. Baseline flow across the coil balloon was 44 +/- 31 mL/min, increasing by a factor of 1.8 +/- 0.7 during pharmacologically induced hyperemia. A mean volume of 14.2 +/- 6.1 mL containing 1416 +/- 608 IU of heparin was infused locally at a pressure of 122 +/- 54 mm Hg. At 7 +/- 1-month follow-up, 1 asymptomatic patient had died, and of the remaining 21, 17 (81%) were asymptomatic. Angiographic follow-up was obtained in 15 of 21 patients (71%), including all 4 symptomatic patients. Mean minimal luminal diameter after the procedure was 2.16 +/- 0.49 mm and at follow-up, 1.89 +/- 0.45 mm, which corresponds to a restenosis rate (diameter stenosis > or = 50%) of 7% (1/15). CONCLUSIONS: Intracoronary use of the coil balloon after balloon angioplasty proved to be feasible and subjectively as well as objectively well tolerated during prolonged deployment by virtue of its perfusion properties. High volumes of heparin solution can be infused locally at very low pressure. No unfavorable clinical or angiographic long-term effects were observed.

Adult↗
PubMed1995

Ischemia-related lesion characteristics in patients with stable or unstable angina. A study with intracoronary angioscopy and ultrasound.

BACKGROUND: Postmortem-derived findings support the common beliefs that lipid-rich coronary plaques with a thin, fibrous cap are prone to rupture and that rupture and superimposed thrombosis are the primary mechanisms causing acute coronary syndromes. In vivo imaging with intracoronary techniques may disclose differences in the characterization of atherosclerotic plaques in patients with stable or unstable angina and thus may provide clues to which plaques may rupture and whether rupture and thrombosis are active. METHODS AND RESULTS: We assessed the characteristics of the ischemia-related lesions with coronary angiography and intracoronary angioscopy and determined their compositions with intracoronary ultrasound in 44 patients with unstable and 23 patients with stable angina. The angiographic images were classified as noncomplex (smooth borders) or complex (irregular borders, multiple lesions, thrombus). Angioscopic images were classified as either stable (smooth surface) or thrombotic (red thrombus). The ultrasound characteristics of the lesion were classified as poorly echo-reflective, highly echo-reflective with shadowing, or highly echo-reflective without shadowing. There was a poor correlation between clinical status and angiographic findings. An angiographic complex lesion (n = 33) was concordant with unstable angina in 55% (24 of 44); a noncomplex lesion (n = 34) was concordant with stable angina in 61% (14 of 23). There was a good correlation between clinical status and angioscopic findings. An angioscopic thrombotic lesion (n = 34) was concordant with unstable angina in 68% (30 of 44); a stable lesion (n = 33) was concordant with stable angina in 83% (19 of 23). The ultrasound-obtained composition of the plaque was similar in patients with unstable and stable angina. CONCLUSIONS: Angiography discriminates poorly between lesions in stable and unstable angina. Angioscopy demonstrated that plaque rupture and thrombosis were present in 17% of stable angina and 68% of unstable angina patients. Currently available ultrasound technology does not discriminate stable from unstable plaques.

Adult↗
PubMed1995

Quantitative assessment with intracoronary ultrasound of the mechanisms of restenosis after percutaneous transluminal coronary angioplasty and directional coronary atherectomy.

The mechanisms of immediate and late changes after percutaneous transluminal coronary angioplasty (PTCA) and directional coronary atherectomy (DCA) were assessed by serial ultrasound imaging in 18 patients treated with PTCA and 16 treated with DCA before, immediately after, and 6 months after coronary interventions. A reduction in plaque area was the main operative mechanism of DCA, explaining 66% of lumen enlargement. In the PTCA group, the increase in lumen area was the result of a more balanced combination of plaque reduction (52% of lumen increase) and increase in total lumen area (48%); p < 0.05 versus DCA. In the PTCA group, this last mechanism was prevalent (p < 0.05) in the lesions showing wall fracture or dissection after treatment and in the lesions with a mixed or calcific composition. In the PTCA group, concentric lesions showed a greater plaque compression than eccentric lesions (p < 0.02). Plaque increase was responsible for 92% and 32% of the late lumen loss after DCA and after PTCA, respectively (p < 0.05). In PTCA patients, a chronic reduction in total vessel area was the main operative mechanism of lumen reduction (67%) and was prevalent in lesions with a mixed or calcific composition. (p < 0.05).

Angioplasty, Balloon, Coronary↗
PubMed1995

Mechanism of high-speed rotational atherectomy and adjunctive balloon angioplasty revisited by quantitative coronary angiography: edge detection versus videodensitometry.

High-speed rotational coronary atherectomy (RA) is primarily used to treat complex lesions. Quantitative angiographic analysis of such complex lesions by edge detection is often unsuitable, whereas videodensitometry, measuring vessel dimensions independently of the target stenosis contours, may offer potential advantages. To gain insight into the operative mechanism of RA and to study the agreement between the two quantitative angiographic methods in measuring the minimal luminal cross-sectional area, the edge detection and videodensitometry techniques were applied to coronary angiograms of 21 lesions in 19 patients with symptoms who underwent successful RA and balloon angioplasty (BA). Obstruction diameter as determined by edge detection increased from 1.00 +/- 0.31 mm before intervention to 1.35 +/- 0.29 mm after RA (p < 0.001) and further increased to 1.74 +/- 0.33 mm after adjunctive BA (p > 0.001). The mean between-method difference (edge detection minus videodensitometry) was 0.34 mm2 before intervention, 0.13 mm2 after RA, and 0.09 mm2 after adjunctive BA (not significant). The standard deviation of the differences decreased from +/- 0.87 mm2 before intervention to +/- 0.80 mm2 after RA (not significant) and increased after BA significantly to +/- 1.21 mm2 (p < 0.05). Thus edge detection and videodensitometry provided equivalent immediate angiographic results after RA and adjunctive BA. The good agreement after RA may reflect the operative mechanism of RA, which by ablation of noncompliant plaque material yields a circular symmetric lumen with smooth surface. The increased dispersion of the between-method differences observed after adjunctive BA presumably results from dissections, plaque ruptures, and loss of luminal smoothness after balloon dilatation.

Absorptiometry, Photon↗
PubMed1995

Can intracoronary ultrasound correctly assess the luminal dimensions of coronary artery lesions? A comparison with quantitative angiography.

In 62 patients with angina pectoris Canadian Class III and IV, the luminal dimensions of 25 pre-PTCA and 56 post-PTCA lesions without occlusion were examined with a 4.3 F 30 MHz mechanical ultrasound imaging catheter, and analysed off-line using ultrasound cross-sectional area (U-CSA) measurements from s-VHS video images (n = 81). In addition, 42 angiographically normal coronary segments were examined. At the site of the examination, the U-CSA was integrated centrally to the leading edge echo of the inner contour of the vessel wall and the corresponding angiographic cinefilm images were analysed by edge detection using the Cardiovascular Angiography Analysis System. The obstruction diameter (at the lesion) and the mean vessel diameter (at normal sites) were used to calculate the angiographic cross-sectional area (A-CSA) assuming a circular model. U-CSA values were compared with the corresponding A-CSA values using t-test and linear regression analysis. The study showed that larger CSA are measured with ultrasound than with angiography. (P < 0.0001). An acceptable correlation was found between U-CSA and A-CSA values in normal coronary segments (correlation coefficient: r = 0.73, mean diff. = 1.44 +/- 1.22 mm2). However, the correlation was poor at the site of pre-PTCA lesions (r = 0.62, mean diff. = 1.81 +/- 1.14 mm2) and deteriorated following PTCA (r = 0.47, mean diff. = 1.28 +/- 2.20 mm2). No correlation was found between the degree of lumen eccentricity measured with intracoronary ultrasound (ICUS) and the individual differences between U-CSA and A-CSA values.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1995

New invasive techniques of assessment of the physiological significance of coronary stenoses in humans.

Pressure and flow velocity can be measured distal to coronary stenoses by means of miniaturized sensors with guidewire technology. This is an alternative non-invasive method of assessing functional coronary vessel stenosis severity, applicable for the intermediate stenoses and for the results of coronary interventions. The complexity of the coronary circulation, however, limits the possibility of establishing simple cut-off criteria to identify flow-limiting stenoses. In this paper, we review advantages and limitations of the different pressure and velocity indices and their application in different clinical settings.

Blood Flow Velocity↗
PubMed1995

Principles of interpretation of coronary velocity and pressure tracings.

The development of quantitative angiography and the introduction of new techniques of intracoronary imaging cannot replace the functional methods for the assessment of stenosis severity. The measurement of the trans-stenotic pressure gradient and of the post-stenotic flow velocity using miniaturized sensors with guidewire technology offers an alternative to the conventional non-invasive methods which is applicable in the catheterization laboratory at the time of the interventional procedure. The complexity of the coronary circulation, however, limits the possibility of establishing simple cut-off criteria to identify the presence of a flow-limiting stenosis. For intermediate lesions, or in the presence of variable haemodynamic conditions, the accuracy of the assessment can be improved by the application of more complex indices, proposed and validated in the animal laboratory and based on the instantaneous relationship between pressure or pressure gradient and flow velocity.

Angioplasty, Balloon, Coronary↗
PubMed1995

New concepts for interpretation of intracoronary velocity and pressure tracings.

The development of quantitative angiography and the introduction of new imaging techniques cannot replace functional methods of assessing the severity of stenosis. Measurement of transstenotic pressure gradient and poststenotic flow velocity using miniaturised sensors with guidewire technology offers an alternative to the conventional non-invasive methods that is immediately applicable in the catheterisation laboratory during interventional procedures. The complexity of the coronary circulation, however, makes it difficult to establish simple cut-off criteria to identify the presence of a flow-limiting stenosis. For intermediate lesions or in the presence of variable haemodynamic conditions, the accuracy of the assessment can be improved by the application of more complex indices proposed and validated in the laboratory animals. Two of these indices are myocardial fractional flow reserve and the slope of the instantaneous relation between pressure or pressure gradient and flow velocity.

Blood Flow Velocity↗