L Barrios

Intravascular ultrasound versus angiography for measurement of luminal diameters in normal and diseased coronary arteries

Quantitation of coronary luminal diameter with a 20 MHz mechanically rotating intravascular ultrasound (IVUS) catheter was compared with orthogonal-view cineangiography by use of a semiautomated edge-detection algorithm in 48 patients undergoing coronary angioplasty. Quantitative comparison of 196 matched segments was attempted, but in only 174 (88.8%) was a direct comparison of the two techniques possible. In angiographically normal coronary arteries (46 segments) the correlation between the values obtained by quantitative coronary angiography (QCA) and those achieved by IVUS was excellent (r = 0.92, p < 0.0001). For mild stenoses (80 segments) the correlation coefficient was only fair (r = 0.467, p < 0.001). After percutaneous transluminal coronary angioplasty the correlation coefficient between IVUS and QCA data (48 segments) was very weak (r = 0.282, p < 0.05). In conclusion, coronary IVUS is feasible and safe and even for a limited range of coronary arterial narrowing, significant correlations between IVUS and QCA measurements of minimal lumen diameter were found. They were excellent in normal coronary arteries, moderate in mildly diseased arteries, and weak after balloon angioplasty.

Infarct Size, Myocardial Hemorrhage, and Recovery of Function After Mechanical Versus Pharmacological Reperfusion Effects of Lytic State and Occlusion Time

BACKGROUND Whether myocardial reperfusion obtained with thrombolysis or primary angioplasty is associated with a similar recovery of function and with the same risk of hemorrhagic infarction is unknown. We evaluated the effects of mechanical and pharmacological reperfusion (with or without a plasma lytic state) on infarct size, myocardial hemorrhage, and left ventricular (LV) function in a canine model. METHODS AND RESULTS Six groups of six dogs were subjected to balloon occlusion of the left anterior descending coronary artery (LAD) followed by 2 hours of reperfusion. The study had a two-by-three factorial design with two occlusion periods (90 and 240 minutes) and three different reperfusion strategies (placebo, 0.4 mg/kg recombinant tissue plasminogen activator, and 40 microg/kg recombinant staphylokinase). In a seventh control group, LAD occlusion was maintained without reperfusion. All dogs received aspirin and heparin. A systemic lytic state was present in staphylokinase-treated dogs. Planimetry of LV slices showed larger infarcts (percent of area at risk) and more hemorrhage (percent of IA) after 240 minutes of occlusion than after 90 minutes of occlusion (54+/-17% versus 37+/-18% and 52+/-27% versus 29+/-27%, respectively; P<.01 for both comparisons), with no significant difference among treatments. Hemorrhage was not observed in the control group without reperfusion. LV angiography showed no differences in global and regional LV function between mechanical and pharmacological reperfusion. CONCLUSIONS In this experimental model, hemorrhagic infarctions of similar extent were observed after both pharmacological and mechanical reperfusion. The extent of hemorrhage was increased by the delay in reperfusion but not by the presence of a lytic state.

The mechanism of disappearance of the physiologic third heart sound with age.

To study the mechanism of disappearance of the physiologic third heart sound (S3) with advancing age, combined phonoechocardiographic and phonomechanocardiographic recordings from 165 normal subjects between 6 and 62 years old were quantitatively analyzed. Nearly all individuals under 40 years old had a recordable S3. Although recordable in 38.6% of the 44 subjects over 40 years old, the physiologic S3 found in adults was less intense and occurred later in diastole when compared with that in children and adolescents. Marked changes in left ventricular filling hemodynamics were observed with aging, including an increase in left ventricular wall thickness and mass, a prolongation of the left ventricular isovolumetric relaxation period, a decrease in left ventricular early diastolic filling and wall thinning rates, and a reduction in the height and steepness of the rapid filling wave measured on the calibrated left apexcardiogram (linear correlation with age significant at p less than .001 for all parameters). Although less pronounced, these changes were very similar to the diastolic abnormalities found in patients with pressure overload left ventricular hypertrophy. Therefore, the higher pressure load imposed on the left ventricular wall due to the well-known gradual increase in blood pressure that occurs during normal growth and adulthood appears to be the most likely explanation for the observed changes in diastolic filling. It is concluded that the later occurrence, the diminishing amplitude, and the eventual complete disappearance of the physiologic S3 with age results from a decrease in early diastolic left ventricular filling and subsequent deceleration of inflow caused by the development of relative left ventricular hypertrophy in adulthood as compared with childhood.

Comparison of clinical complications, angiographic results, and device usage of coronary angioplasty using low‐ and high‐compliance balloons

We randomized 800 patients in a prospective study comparing the angiographic results, device usage and in-hospital outcome of balloon angioplasty of primary stenoses of native coronary vessels with low-compliant and highly compliant balloons. The cumulative incidence of prespecified clinical endpoints was 8.0% in both treatment groups. The primary angiographic success rates were 83.9% and 78.9% in the high- and low-compliance group, respectively (P = 0.05). For the lesions dilated with one study balloon only, the quantitative angiographic findings were virtually identical in the two treatment groups. The total number of dissections was slightly but not significantly higher in the lesions treated with a highly compliant balloon. The global usage of angioplasty balloons was similar in both treatment groups. We conclude that, in general, there is no objective reason to prefer one balloon material to another on the basis of its compliance characteristics.

Two-dimensional myocardial strain rate estimation using "snakes"

In this study, the feasibility of two-dimensional strain rate estimation of the human heart in vivo is shown. To do this, ultrasonic B-mode data were captured at a high temporal resolution of 3.7 ms and processed off-line. The motion of the radio-frequency signal patterns within the two-dimensional sector image was tracked and used as the basis for strain rate estimation. Both axial and lateral motion and strain rate estimates showed a good agreement with the results obtained by more established, one-dimensional techniques.