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Necropsy examinations and epicardial ultrasound studies have suggested that atherosclerotic coronary arteries undergo compensatory enlargement. This increase in vessel size may be an important mechanism for maintaining myoccardial blood flow. It also is of fundamental importance in the angiographic study of coronary disease progression and regression. The purpose of this study was to determine, using intracoronary ultrasound, whether coronary arteries undergo adaptive expansion in vivo. Forty-four consecutive patients were studied (30 men, 14 women; mean age 56 [+ or -] 10 years). Eighty intravascular ultrasound images were analyzed (32 left main, 23 left anterior descending and 25 right coronary arteries). Internal elastic lamina area, a measure of overall vessel size increased as plaque area expanded (r = 0.57, p = 0.0001, SEE = 5.5 [mm.sup.2]). When the left main, left anterior descending and right coronary arteries were examined individually, there continued to be as great or greater positive correlation between internal elastic lamina and plaque area (left anterior descending r = 0.75, p = 0.0001; right coronary arteries: r = 0.63, p = 0.0007; left main: r = 0.56, p = 0.0009), implying that each of the vessels and all in aggregate underwent adaptive enlargement. When only those vessels with

Intraluminal ultrasonography of the common duct was performed in nine patients undergoing laparoscopie cholecystectomy, using a system comprising a 20-MHz crystal in a 95-em, blunt-tipped 6F sheath, mechanically rotated at 1,800 rpm. The probe was introduced through an incision in the cystic duct and passed into the duodenum. When the catheter was withdrawn, excellent visualization of the common and cystic ducts and lower end of the common hepatic duet was achieved. In seven patients, the biliary tree was normal. A small calculus was discovered in the common duct in one patient. This stone was not seen on a subsequent eholangiogram and was subsequently retrieved. An additional patient had mucus or sludge noted in the duct, which cast no acoustic shadow and thus was distinguished from calculi. The technique was fast, efficient, and easy to perform in this small group of patients and holds promise for screening the common duct pathology during laparoscopic cholecystectomy.

The time course of left ventricular (LV) filling and LV diastolic performance were examined in 27 consecutive patients in sinus rhythm before and acutely after balloon mitral valvotomy (BMV). The mitral valve area acutely increased from 1.1 [+ or -] 0.3 to 2.1 [+ or -] 0.8 [cm.sup.2]. Simultaneous pressure-volume data were obtained using digital subtraction left ventriculography and LV micromanometer pressure before and 10 minutes after BMV. The time constant of LV isovolumic relaxation was unchanged after BMV (50 [+ or -] 10 ms before BMV vs 47 [+ or -] 13 ms after BMV). In addition, values before and after BMV for LV end-diastolic volume (123 [+ or -] 29 vs 125 [+ or -] 36 ml), end-diastolic pressure (11 [+ or -] 4 vs 12 [+ or -] 4 mm Hg) and diastolic filling time (337 [+ or -] 126 vs 338 [+ or -] 152 ms) were not altered by the procedure. After BMV the peak diastolic filling rate (403 [+ or -]143 vs 469 [+ or -] 302 ml/s) maintain despite a 36% reduction in left atrial filling pressure. There was a trend toward earlier occurrence of the peak filling rate (196 [+ or -] 127 vs 146 [+ or -] 148 ms, p = 0.08). The percentage of diastolic filling in the first third of diastole, however, was similar (42 [+ or -] 9 vs 48 [+ or -] 16%) before and after the procedure. Thus, the time course of LV filling is not significantly altered acutely after BMV, but is maintained at reduced left atrial filling pressure. Neither LV relaxation or LV chamber compliance are altered acutely after BMV. Changes in LV diastolic performance, which have recently been shown to alter Doppler mitral valve half-time measurements independent of changes in valve area, do not contribute to the decreased correlation between Doppler and invasive data observed acutely after BMV. In addition, the lack of impairment of LV isovolumic relaxation suggests that LV ischemia or papillary muscle injury are unlikely to contribute to increased mitral regurgitation after BMV.

Doppler echocardiography measures the rate of blood flow by determining a shift in the frequency of ultrasonic sound waves reflected by the moving fluid. This method is now routinely applied to measuring the blood flow out of the heart through the aorta in patients with aortic stenosis, a narrowing of the aortic valve (which separates the left ventricle and the aorta). Often the measurements are quite complex and are used in mathematical calculations; since these calculations are both time-consuming and tedious, it would be useful to determine if simpler and more straight-forward measurements might be just as useful. Doppler echocardiographic measurements were made on 680 adults undergoing balloon valvuloplasty to widen the narrowed valve. All patients suffered from severe symptoms of aortic valve stenosis. The results of the study indicated that there was tremendous variability among the patients, and that the severity of symptoms could not be predicted on the basis of the Doppler measurements alone. Furthermore, there were cases in which the Doppler measurements could have been misleading. Patients with a small pressure difference between the two sides of the valve might appear to have only minor stenosis. However, if the blood flow is also low, the stenosis may be large despite the small pressure difference. In such cases, it would be important to calculate the valve area from the Doppler measurements. The lack of correlation between the Doppler measurements and the severity of symptoms suggests that other factors may be more important. For example, other studies have suggested that the diastolic function of the left ventricle, that is, the filling of the left ventricle with blood as it relaxes, may be more important in determining the actual symptoms of valvular aortic stenosis. (Consumer Summary produced by Reliance Medical Information, Inc.)

Validation of catheter-based intravascular ultrasound imaging has been based on comparisons with histology and digital angiography, each of which may have limitations in the assessment of arterial size and morphology. External, high-frequency ultrasound can accurately determine vessel dimensions and morphology and because, like intravascular ultrasound, it also provides crosssectional arterial ultrasound images, it may be a more appropriate technique for the in vivo comparison of arterial dimensions and morphology determined by intravascular ultrasound. Thus, intravascular ultrasound, external 2dimensional ultrasound, Doppler color-flow imaging and digital angiography were compared for assessment of arterial dimensions and war morphology at 29 femeral artery sites in 15 patients. Intravascular ultrasound and the other 3 imaging modalities correlated well in determination of lumen diameter (2-Dimensional, r = 0.98, standard error of the estimate [SEE] = 0.14; Doppler color flow, r = 0.91, SEE = 1.11; angiography, r = 0.95, SEE = 0.91) and cross-sectional area (2-dimensional, r = 0.97, SEE = 0.04; Doppler color flow, r = 0.92, SEE = 0.14; angiography, r = 0.96, SEE = 0.08). However, lumen size measured by Doppler color flow was consistently smaller than that measured by the other 3 imaging modalities. Intravascular ultrasound detected arterial plaque at 15 sites, 5 of which were hypoechoic (soft) and 10 hyperechoic with distal shadowing (hard). Plaque was identified at 12 of 15 sites by 2-dimensional imaging (p = 0.30 vs intravascular ultrasound), but at only 6 of 15 sites by angiography (p = 0.003 vs intravascular ultrasound), only 1 of which was thought to be calcified plaque. These data indicate that arterial dimensions determined by intravascular ultrasound correlate well with both external ultrasound and angiography in normal and minimally diseased peripheral arteries. Doppler color flow underestimates true lumen size. Angiography is often discordant with both intravascular and external ultrasound in determining the presence and composition of arterial plaque. (Am J Cardiol 1991,-67:817-M), Vascular imaging techniques are important for examining blood vessels for decreased size, vessel wall damage, accumulation of fatty plaque (hardened material stuck to wall of blood vessel) and other signs of disease. Currently used imaging techniques include external ultrasound, which uses high-frequency sound waves to image vessel dimensions and flow of blood vessels from outside the body, and digital angiography, which uses X-rays of vessels after a contrast material has been injected into them. A newly developed technique for these purposes is intravascular ultrasound. It also uses high-frequency sound waves for imaging purposes, but does so within the vessels by means of a catheter inserted into the vessels. This accuracy of this technique has not been completely validated and its results have conflicted with results from angiography regarding changes inside the vessel. Either intravascular ultrasound is more sensitive than older methods, or else it cannot accurately determine vessel morphology. All four imaging techniques were evaluated for measuring vessel dimensions and morphology to examine the accuracy of this intravascular ultrasound. Fifteen patients with no prior history of peripheral artery disease were examined using two-dimensional and Doppler external ultrasound, intravascular ultrasound, and digital subtraction angiography. Results from all four methods were approximately equivalent in measurements of vessel diameters and cross-sectional areas. Intravascular ultrasound detected 15 plaque sites, with external ultrasound finding 12 of these 15, and angiography imaging only 6 of them. On the other hand, neither angiography nor external ultrasound found plaque sites not found by intravascular ultrasound. Interpretations of angiography and intravascular ultrasound disagreed in 9 out of 10 cases of hard plaques as to whether the lesions were calcified. These results demonstrate intravascular ultrasound can determine vessel dimensions as well as other techniques. It also seems better able to find plaque sites. Further research needs to be done to see if is more accurate than angiography in characterizing these plaque sites. (Consumer Summary produced by Reliance Medical Information, Inc.)

The incidence of major complications associated with nonionic contrast media has not been defined in a large study. Accordingly, cardiovascular complications, especially thrombotic events, were prospectively evaluated in 8,5l7 consecutive patients undergoing diagnostic cardiac catheterization with either lepamidol (n = 6,293) or lehexol (n = 2,224). Thrombotic events were defined as coronary embolus, coronary occlusion, transient ischemic attack or stroke occurring at the time of catheterization. Thrombotic events occurred in 15 patients (0.18%). Coronary thrombus or embolus occurred in 7 patients, a thromboembolus ft= the ventricular catheter occurred in 1 patient and transient ischemic attack or stroke occurred in 7 patients. Six of 15 patients with thrombotic events were premedicated with heparin. Thrombotic events were unusual in that they tended to occur in clusters within short time intervals. On 1 occasion, a thrombus was observed in the catheter tip before embelization. Other cardiovascular complications were similarly low with an incidence of ventricular tachycardia/fibrillation of 0.1%, profound bradycardia of 0.2% and prolonged angina of 0.3%. There were 2 deaths unrelated to thrombotic events. Although the clinical thrombotic events associated with nonionic contrast have an unusual temperal clustering and may result in major complications, the overall incidence (0.18%) of these thrombotic complications with nonionic contrast agents is quite similar to that reported with ionic contrast media. (Am J Cardiol 1990;6S:1481-1484), Contrast media are substances used in imaging procedures and allow visualization of heart function during cardiac catheterization (when a catheter is fed through a blood vessel to a chamber of the heart). Some complications have been associated with these media, especially ionic media (which are charged substances, like acids). In studies of small groups of patients, nonionic contrast media have been reported to cause fewer complications, but they can not prevent clotting as ionic media can. The incidence of complications related to nonionic contrast media, used during cardiac catheterization, was studied in 8,517 patients. Thrombotic events, including coronary thrombus (blood clot in a coronary artery), transient ischemic attack (inadequate blood flow in the brain), or stroke (brain damage caused by obstruction of blood flow), occurred in 15 patients, a frequency of 0.18 percent. Six of the patients with thromboses (clot formation) had been premedicated with heparin, an anticoagulant. The events occurred in clusters during the course of the study, but could not be related to the lot number of the media, equipment, or staff members. There was a low frequency of other cardiovascular events, such as rapid and slow heartbeat, and arrhythmia (abnormal heart rhythm). Two deaths, unrelated to contrast media, occurred. The results confirm that there is a low incidence of cardiovascular and thrombotic events in catheterization procedures which use nonionic contrast media, and suggest that pretreatment with heparin does not affect thrombotic outcome. (Consumer Summary produced by Reliance Medical Information, Inc.)

The study of physiology seems to be the study of compensatory mechanisms and alterations that attempt to maintain bodily functions in the face of internal and external changes. For example, in patients with aortic stenosis, the flow of blood through the aortic valve is restricted. The heart compensates by increasing pressure to maintain the blood flow, and eventually the size of the left ventricle increases to deliver the increased demand for force during contraction of the ventricles, or systole. What happens when the obstruction is abruptly cleared from the aorta, as results from the surgical procedure balloon valvuloplasty? Data were recorded from 25 patients before and after balloon valvuloplasty. The immediate reduction in blood flow restriction after the operation results in a decrease in the systolic blood pressure, in this study from a mean of 206 to 175 mm Hg. However, no change was observed in the heart rate or the output of the heart in liters per minute. The results document that cardiac function is the result of an interaction of complex and variable factors. (Consumer Summary produced by Reliance Medical Information, Inc.)

The long-term benefits of balloon aortic valvuloplasty are not usually predictable. This procedure involves restorative surgery of the aorta, the main trunk of the arterial system. Cardiac deterioration and symptoms such as valvular restenosis (a recurring narrowing or stricture of the valves of the heart) are common and may occur shortly after aortic valvuloplasty is performed. Left ventricular (LV) function was examined in 81 patients who had balloon aortic valvuloplasty. (The LV is the main pumping chamber of the heart; it pumps blood to the body via the aorta.) Three months after their surgery 65 percent of the patients (53) showed improvement; 35 percent (28 patients) had regressed to their former condition, worsened, or died. Less than half of the patients with low ejection fractions showed any improvement when examined at three months; LV ejection fraction was an independent predictor of poor prognosis and patients who did not improve had more frequent irregular test results of LV performance. It was concluded that LV performance is predictive of how well patients will respond after balloon aortic valvuloplasty. When short-term outcomes were evaluated, patients with depressed LV function were less likely to show overall improvement. Patients maintaining their baseline LV function had better short-term results from this procedure. Balloon aortic valvuloplasty is not recommended as an effective treatment for individuals with depressed LV function, and sustained improvement of symptoms cannot be anticipated from this procedure in this group of patients.