The similar two-year mortality in the hydralazine-isosorbide dinitrate arms in our previous Vasodilator-Heart Failure Trial (26 percent) and in the present trial (25 percent), as compared with that in the placebo arm in the previous trial, (34 percent) and the further survival benefit with enalapril in the present trial (18 percent) strengthen the conclusion that vasodilator therapy should be included in the standard treatment for heart failure. The different effects of the two regimens (enalapril and hydralazine-isosorbide dinitrate) on mortality and physiologic end points suggest that the profile of effects might be enhanced if the regimens were used in combination.

The importance of surface topology and implant material composition on osseointegration in trabecular bone was investigated using three commericially used implant materials and surface-texturing procedures which included blasting, high temperature acid etching, and hydroxyapatite (HA) coating. Surface roughness and spacing parameters were measured for each implant group with a laser interferometric profilometer. Cylindrical implants were press-fit into trabecular bone sites in the knee of mature miniature pigs. After 12 weeks in situ, osseointegration was evaluated by (1) mechanical pushout tests to measure bone-implant interface strength and (2) quantitative morphometric measurements of the percent implant surface covered by bone. We found that HA-coated implants showed superior osseointegration in terms of both pushout failure load and surface coverage by bone measurements. An excellent correlation (r2 = .90) was found between the average roughness of the implant surface and pushout failure load. New methods for altering the local topologic and/or chemical state of the implant surface (i.e., by acid etching) may provide an important new avenue of research for improving the osseointegrative properties of orthopedic materials.

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SUMMARY Using wide-angle, phased-array, two-dimensional echocardiography, mitral leaflets and their annular attachments were recorded from a view close to the standard apical four-chamber view. The transducer was rotated and recordings were made at 300 rotational intervals around the circumference of the mitral valve annulus. To reconstruct the annulus, diameters (or chords) from each rotational interval were arranged around a reference point. This was done for 12 times during the cardiac cycle. Annular areas were planimetered and circumferences measured. Correlation was good for areas reconstructed and measured by the same observer on separate occasions (r = 0.963) and by two different observers (r = 0.987). In 11 normal subjects the annular area index (area divided by body surface area) increased during diastole to a maximum of 3.8 ± 0.7 cm2/m2 (mean ± SD) in late diastole. There was presystolic followed by systolic narrowing to a minimum in midsystole. The mean reduction in area was 26 3%. The maximal annular circumference was 9.3 ± 0.9 cm and the mean reduction in circumference was 13 3%. The overall motion pattern was similar to that reported in experimental studies in the dog. Mitral annular reconstruction may provide new information about normal and abnormal function of the mitral valve apparatus.IN EXPERIMENTAL STUDIES and in human subjects on cardiopulmonary bypass, the size of the mitral valve annulus has been reported to change during the cardiac cycle.'-" There has been no technique available to measure mitral annular areas during the cardiac cycle in human subjects. Little is known of the size and motion of the mitral annulus in intact man, although important observations relating to its size have been made at autopsy.6-'0 Study of the mitral valve annulus may provide new insights into the overall function of the mitral valve apparatus in health and disease.We used a two-dimensional echocardiographic technique to reconstruct the mitral valve annulus so that its area could be measured at different times during the cardiac cycle to examine phasic changes. tape using a Sanyo cassette recorder. The images could be redisplayed in real-time, slow motion or as single frames. Still frames were recorded on 90-mm film during real-time studies and are used as illustrations in this paper. Mounted on the echocardiographic transducer was an inclinometer,"' a circular, fluid-filled chamber containing an air bubble that allows measurement of 300 transducer rotational intervals.Our method was designed to reconstruct the mitral valve annulus at 12 times during the cardiac cycle from diameters and chords measured at 300 rotational intervals. The transducer was held at the left ventricular apical impulse and the beam was directed toward the left atrium and the mitral valve leaflets to identify their annular hinge points. A view close to the standard apical four-chamber view was usually the initial plane of examination. Additional planes were obtained at 300 rotational intervals. Six planes were used to provide chords o...

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Recent intravascular ultrasound experience challenges the accuracy of ultrasonic measurement of arterial wall thickness. We reevaluated the correlation between histological and sonographic measurements of intima-media thickness using standard transcutaneous vascular technology. Carotid and femoral arterial segments were imaged before and after fixation using a 7-MHz linear-array vascular transducer. Log compression and beam orientation were varied. Mean intima, media, and adventitia thicknesses were measured and compared with corresponding histological tunica. Tissue processing caused 2.5% shrinkage. Intraobserver reading error was 0.7% for histology and 5.4% for sonography. Ultrasound overestimated the thickness of the intima and adventitia and underestimated the thickness of the media. For combined intima-media thickness, the differences between histology and imaging were insignificant, averaging 4% for the carotid artery and 9% for the femoral artery in the far-wall projection. In the near-wall projection, sonographic intima-media thickness was 20% less than that determined histologically. We conclude that ultrasonography is limited mainly by axial resolution in quantifying the dimensions of individual arterial tunica but is capable of accurately measuring far-wall intima-media thickness. ( In the evolution of these applications, the technology has met rigorous standards of reproducibility for measuring carotid intima-media thickness.3 The validity and accuracy of the measurement are based on pathological and clinical correlations described by Pignoli et al 4 in 1986. However, recent data from intravascular ultrasound experience have challenged the accuracy of quantitative transcutaneous vascular sonography. 5 - 9Our purpose was to reevaluate in vitro measurements of arterial wall segment thicknesses obtained by histology and by current vascular sonography. We found systematic differences that are inherent with ultrasound technology but do not invalidate the quantification of intima-media thickness. Methods Segments from common carotid and femoral arteries were taken during the autopsies of 36 male subjects who died at an age of 69 ±8 (mean±l SD) years. After removing fat and loose tissue from the adventitia, the vessels were opened longitudinally. They were then clamped to frames for fixation in 10% formalin and for imaging before and after fixation. The specimens were divided longitudinally in the line of the imaging plane. A block of tissue measuring 20 x 2.5 x thickness of the wall (mm 3 ) was taken from the vertical center of either side of the imaging plane, corresponding with the center of the sonogram (Figure 1). The cut edges were photographed on 35-mm slide film to determine the amount of shrinkage incurred during histological processing. HistologyThe sections were marked with india ink for orientation and placed in perforated plastic cassettes for ethanol dehydration, xylene substitute clearing, and paraffin embedment. Four sections (5 ftm thick) were sectioned by rotary microtome from the imaging ...

The possible role of mechanical loading history in chondroosseous development at the ends of long bones is explored using two-dimensional finite element models of chondroepiphyses. Loading histories are characterized in terms of discrete loading cases defined by joint contact pressure distributions and an associated number of loading cycles. An osteogenic stimulus throughout the chondroepiphyses is calculated following the theory that cyclic octahedral shear stresses promote endochondral ossification and cyclic compressive dilatational stresses inhibit ossification. The resulting distributions for the osteogenic stimulus predict the appearance of the secondary ossific nucleus and the shape of the developing bony epiphysis. The zone of Ranvier and the formation of articular cartilage and the growth plate are also predicted by the models. These findings are consistent with the hypothesis that tissue stress histories constitute an important influence during skeletal morphogenesis. Further study and testing of the concepts introduced in this study are appropriate.