Carbon dioxide (CO2) angiography in children.

BACKGROUND: When iodinated contrast material is contraindicated, carbon dioxide (CO2) gas can be injected intravascularly to produce high-quality digital subtraction angiograms. OBJECTIVE: CO2 angiography, although previously described in adults, has never before been reported in children. MATERIALS AND METHODS: We present three children with renal transplants who required renal angiography. Because of elevated creatinine levels, iodinated contrast was not used to search for possible renal artery stenosis. Instead, CO2 angiography was used to evaluate the renal artery anastomosis. RESULTS: In all three cases, the renal artery anastomosis was clearly visualized using CO2 angiography and showed no evidence of renal artery stenosis. CONCLUSION: Digital CO2 angiography is an effective method for pediatric renal angiography. The technique can easily be adapted for virtually any angiographic laboratory capable of digital subtraction imaging. Digital CO2 angiography also lacks the risks of a conventional iodinated contrast medium, namely nephrotoxicity, allergic reaction and volume overload.

Massive air embolus to the left ventricle: diagnosis and monitoring by serial echocardiography.

Air embolization is an unusual but potentially dangerous complication in left heart catheterization. Microbubbles can be detected with two-dimensional echocardiography, which is often used for this purpose during open heart and bypass surgeries. Permanent neurologic sequelae and hemodynamic collapse can result from embolization of air bubbles to the cerebral and coronary circulations, respectively. Hyperbaric oxygen is the treatment of choice for cerebral air embolization. We present a 39-year-old man who had air embolization during left ventriculography in the form of a large pocket of "pooled" air. The patient was treated with conservative therapy successfully. Two-dimensional transthoracic echocardiography was used to document the presence of the air and follow its dissolution.

Echo Doppler evaluation of patients with acute mitral regurgitation: superiority of transesophageal echocardiography with color flow imaging.

Acute mitral regurgitation is a medical emergency that requires prompt, accurate diagnosis and urgent therapy. Although the use of echo Doppler imaging has been described in these patients, preliminary observations have suggested that color flow Doppler performed from the standard transthoracic windows may underestimate the severity of mitral insufficiency in this setting. The aim of this study was to compare transesophageal color Doppler quantitation of regurgitation with results obtained from standard transthoracic windows in patients with acute, severe mitral regurgitation. Two-dimensional echocardiography with pulsed, continuous, and color flow Doppler was performed by both transthoracic and transesophageal methods in 16 consecutive patients who were documented to have acute severe mitral insufficiency by catheterization. Transthoracic and transesophageal scans were reviewed by two blinded observers and assessed for the detection of mitral regurgitation by transthoracic pulsed wave (81%), continuous wave (100%), and color flow Doppler (81%) compared with transesophageal color flow imaging (100%; p = NS). Severity of mitral regurgitation was graded as none, mild, moderate, or severe on the basis of existing transthoracic pulsed wave and color flow criteria and compared with transesophageal color flow grading. At first examination patients were critically ill, with elevated pulmonary wedge pressures (mean 27 +/- 7 mm Hg) and V waves (mean 45 +/- 10 mm Hg). Fifteen of the patients underwent emergency surgery, and the overall hospital mortality rate was 12%. Maximal color flow jet areas were significantly greater on transesophageal scanning (mean 10.5 cm2) compared with transthoracic color jets (mean 2.3 cm2).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary reactivity to nitroglycerin: intravascular ultrasound evidence for the importance of plaque distribution.

OBJECTIVES: This study was designed to assess the extent and timing of vasodilation after intracoronary administration of nitroglycerin using intravascular ultrasound. We also sought to relate the magnitude of nitroglycerin-induced dilation to the distribution of atherosclerotic plaque. BACKGROUND: Although previous angiographic studies have shown that nitroglycerin can dilate both normal and stenotic coronary arteries, it remains uncertain whether atherosclerotic vessels can respond to nitroglycerin to the same extent as normal arteries in the clinical setting. METHODS: We analyzed a total of 48 segments from 48 patients by means of a multielement 3.5F to 5.5F 20-MHz intravascular ultrasound system before and after intracoronary administration of nitroglycerin (250 micrograms). Videotaped images were digitized, and the lumen cross-sectional area was measured with an electronic cursor. In noncircumferential lesions, the perimeters of the normal and diseased portions were measured separately to compare the reactivity to nitroglycerin in each portion. RESULTS: Of 48 sites examined 14 were normal by ultrasound, and 34 revealed atherosclerotic lesions. In the 14 normal segments nitroglycerin produced a large increase in cross-sectional area (31 +/- 16% [mean +/- SD]) within 60 s after injection. In the 34 atherosclerotic segments, nitroglycerin-induced dilation was impaired, and the cross-sectional area increased only 12 +/- 8% (p < 0.01). In 15 of 34 atherosclerotic segments, a noncircumferential lesion was identified, and the cross-sectional area after nitroglycerin increased an average of 17 +/- 6%. In the remaining 19 sites, circumferential disease was present, and the cross-sectional area increased by only 8 +/- 7% (p < 0.05 vs. normal or noncircumferential atherosclerotic segments). In noncircumferential lesions, the increase in the perimeter of the normal portion of the wall was significantly greater (14 +/- 6%) than the increase in the diseased portion (5 +/- 3%, p < 0.05). CONCLUSIONS: These data indicate that vasoreactivity after nitroglycerin administration is reduced in segments with atherosclerosis by ultrasound. We suggest that nitroglycerin-induced vasodilation at the stenotic segments can be produced primarily by expansion of the nondiseased portion of the vessel wall.

Prognostic value of Doppler transmitral flow patterns in patients with congestive heart failure.

OBJECTIVES: This study was designed to determine whether Doppler echocardiographic transmitral flow patterns can predict cardiac mortality in patients with congestive heart failure. BACKGROUND: Previous studies have indicated that Doppler transmitral flow patterns are related to New York Heart Association functional class and exercise capacity in patients with congestive heart failure. However, the prognostic significance of these flow patterns is not known. METHODS: We analyzed the relation of transmitral flow patterns and cardiac mortality in 100 consecutive patients (76 men, 24 women; mean [+/- SD] age 60 +/- 11 years) with congestive heart failure symptoms and left ventricular ejection fraction < 40%. At the time of entry into the study, functional class and ejection fraction by radionuclide angiography were determined, and Doppler echocardiography was performed in all patients. Transmitral flow was obtained from the apical four-chamber view at the mitral annulus level. Measurements included early (E) and atrial (A) filling velocities, E/A ratio and deceleration time of the E wave. The patients were assigned to two groups according to E/A ratio or deceleration time of transmitral flow patterns, or both: a non-restrictive group (42 patients) with E/A < or = 1 or E/A = 1 to 2 and deceleration time > 140 ms, and a restrictive group (58 patients) with E/A > or = 2 or E/A = 1 to 2 and deceleration time < or = 140 ms. RESULTS: Of 100 patients, 26 died during a mean follow-up period of 16 +/- 8 months. The cumulative cardiac mortality rate determined by the Kaplan-Meier method was 14% at 1 year and 35% at 2 years. Cox proportional hazards model analysis revealed that transmitral flow (restrictive vs. nonrestrictive, chi-square 6.99, p = 0.008), patient gender (female vs. male, chi-square 4.59, p = 0.03) and New York Heart Association functional class (IV vs. II, chi-square 3.95, p = 0.05) were significantly related to cardiac mortality in patients with congestive heart failure. Mortality rate in the restrictive group was markedly higher than that in the nonrestrictive group at 1 year (19% vs. 5%, respectively, p < 0.05) and at 2 years (51% vs. 5%, respectively, p < 0.01) by log-rank test. Relative risk for cardiac death was estimated as 4.1 at 1 year and 8.6 at 2 years in the restrictive group compared with the nonrestrictive group. CONCLUSIONS: In patients with congestive heart failure, a restrictive transmitral flow pattern, female gender and advanced functional class are predictive of higher cardiac mortality. The restrictive transmitral flow pattern by Doppler echocardiography is the single best clinical predictor for cardiac death in patients with congestive heart failure.

Intravascular ultrasound of the coronary arteries: current applications and future directions.

Although angiography is widely applied in the diagnosis of the coronary artery disease (CAD), studies have questioned the accuracy of radiographic methods. Miniaturized intravascular ultrasound devices offer several potential advantages, including a tomographic orientation and the ability to characterize atherosclerotic plaques. Two dissimilar technical approaches to transducer design have emerged: mechanically rotated devices and multi-element arrays, each yielding small coronary catheters (1.1-1.8 mm in diameter). Initial studies of coronary ultrasound have demonstrated few serious untoward effects. In most normal subjects, the vessel wall is laminar in appearance with an intimal leading edge and subintimal sonolucent layer averaging less than or equal to 0.20 mm in thickness. In most CAD patients, the thickness of the leading-edge or sonolucent zone is abnormally increased. Atherosclerotic abnormalities are frequently evident in segments with no angiographic lesion. At sites with a circular lumen shape, minimum diameter by ultrasound and angiography correlate closely, r = 0.93. At sites with an eccentric lumen, significant disagreement between angiography and ultrasound diameter is evident, r = 0.78. Correlation between angiography and ultrasound from percent stenosis is moderate, r = 0.63. Following balloon angioplasty percutaneous transluminal coronary angioplasty (PTCA), morphologic findings include complex cracks, splits, and dissections, and minimum lumen diameter by angiography and intravascular ultrasound correlate poorly. Recent advances have improved the utility of coronary ultrasound, including smaller catheters and a device combining a miniature imaging transducer (1.16 mm) with a low profile balloon (0.028-0.033 inch). Important current limitations include inability to visualize the smallest coronaries and tight stensoses. The future of coronary ultrasound is promising, propelled by the unique capability of this modality to image atherosclerotic plaques directly.

Influence of operator- and patient-dependent variables on the suitability of automated quantitative coronary arteriography for routine clinical use.

This study was designed to elucidate the operator- and patient-dependent variables inherent in clinical application of quantitative coronary arteriography. Digital arteriograms from 25 consecutive patients undergoing diagnostic catheterization were analyzed by four experienced angiographers utilizing an automated coronary edge detection system to measure percent area stenosis. The identification of potentially significant lesions for quantitation constituted a major source of variability, with unanimous agreement on the presence of a greater than or equal to 50% stenosis occurring at 38 (29%) of the 130 reported sites. Selection of an optimal frame for quantitative analysis resulted in disagreement for every lesion reported. Frame selection by the operator, as opposed to measurement of preselected frames, increased the interobserver variability from 5% to 7% for automated geometric analysis (p less than 0.01), and from 8% to 10.5% for automated densitometric analysis (p less than 0.01). Fully automatic arterial border detection was possible for only 20 (52.5%) of the 38 unanimously identified stenoses. The 18 failures involved one or more of the following factors: 1) stenosis at a bifurcation (13 [72%]); 2) diffuse, severe disease (8 [44%]); 3) excessive vessel tortuosity or overlap or both (4 [22%]); and 4) poor image quality (5 [28%]). In contrast, the same automated border detection algorithm successfully traced all 15 preselected frames of discrete stenoses referred for coronary angioplasty. Automated quantitative coronary arteriography performs well when carefully selected, discrete stenoses are presented to the computer for analysis. However, quantitative analysis of routine clinical coronary arteriograms is limited by operator-dependent variability in stenosis identification and frame selection, as well as by complex coronary anatomy and suboptimal image quality. These limitations make automated quantitative coronary arteriography impractical for routine clinical use.

Intravascular ultrasound assessment of lumen size and wall morphology in normal subjects and patients with coronary artery disease.

BACKGROUND: Necropsy studies demonstrate that coronary artery disease (CAD) is frequently complex and eccentric. However, angiography provides only a silhouette of the vessel lumen. Intravascular ultrasound is a new tomographic imaging method for evaluation of coronary dimensions and wall morphology. Few data exist regarding intravascular ultrasound in patients with CAD, and no data exist for subjects with normal coronaries. METHODS AND RESULTS: We used a multielement 5.5F, 20-MHz ultrasound catheter to examine eight normal subjects and 43 patients with CAD. We assessed the safety of coronary ultrasound and the effect of vessel eccentricity on comparison of minimum luminal diameter by angiography and ultrasound. Normal and atherosclerotic wall morphology and stenosis severity were also evaluated by intravascular ultrasound. The only untoward effect was transient coronary spasm in five patients. At 33 sites in normal subjects, the lumen was nearly circular, yielding a close correlation between angiographic and ultrasonic minimum diameter (r = 0.92). At 90 sites in patients with CAD, ultrasound demonstrated a concentric cross section; correlation was also close (r = 0.93). However, at 72 eccentric sites, correlation was not as close (r = 0.77). For 41 stenoses, correlation between angiography and ultrasound for area reduction was moderate (r = 0.63). In normal subjects, wall morphology revealed a thin (0.30 mm or less) intimal leading edge and subadjacent sonolucent zone (0.20 mm or less). Patients with CAD exhibited increased thickness and echogenicity of the leading edge, thickened sonolucent zones, and/or attenuation of ultrasound transmission. CONCLUSIONS: These data establish that intravascular ultrasound is feasible and safe and yields luminal measurements that correlate generally with angiography. Differences between angiographic and ultrasound measures of lumen size in eccentric vessels probably reflect the dissimilar perspectives of tomographic and silhouette imaging techniques. Intravascular ultrasound provides detailed images of normal and abnormal wall morphology not previously possible in vivo.

A prospective, randomized trial comparing combination half-dose tissue-type plasminogen activator and streptokinase with full-dose tissue-type plasminogen activator. Kentucky Acute Myocardial Infarction Trial (KAMIT) Group.

BACKGROUND: The potential benefits of combination thrombolytic agents in the treatment of myocardial infarction remain uncertain. In a small pilot study, we demonstrated that combining half-dose tissue-type plasminogen activator (t-PA) with streptokinase (SK) achieved a high rate of infarct vessel patency and a low rate of reocclusion at half the cost of full-dose t-PA. METHODS AND RESULTS: We designed a prospective trial in which 216 patients were randomized within 6 hours of myocardial infarction to receive either the combination of half-dose (50 mg) t-PA with streptokinase (1.5 MU) during 1 hour or to the conventional dose of t-PA (100 mg) during 3 hours. Acute patency was determined by angiography at 90 minutes, and angioplasty was reserved for failed thrombolysis. Heparin and aspirin regimens were maintained until follow-up catheterization at day 7. Acute patency was significantly greater after t-PA/SK (79%) than with t-PA alone (64%, p less than 0.05). After angioplasty for failed thrombolysis, acute patency increased to 96% in both groups. Marked depletion of serum fibrinogen levels occurred after t-PA/SK compared with t-PA alone at 4 hours (37 +/- 36 versus 199 +/- 66 mg/dl, p less than 0.0001) and persisted 24 hours after therapy (153 +/- 66 versus 252 +/- 75 mg/dl, p less than 0.0001). Reocclusion (3% versus 10%, p = 0.06), reinfarction (0% versus 4%, p less than 0.05), and need for emergency bypass surgery (1% versus 6%, p = 0.05) tended to be less in the t-PA/SK group. Greater myocardial salvage was apparent in the t-PA/SK group as assessed by infarct zone function at day 7 (-1.9 SD/chord versus -2.3 SD/chord after t-PA alone, p less than 0.05). In-hospital mortality (6% versus 4%) and serious bleeding (12% versus 11%) were similar between the two groups. CONCLUSIONS: These results suggest that a less expensive regimen of half-dose t-PA with SK yields superior 90-minute patency and left ventricular function and a trend toward reduced reocclusion compared with the conventional dose of t-PA.

Acute effects of parenteral beta-blockade on regional ventricular function of infarct and noninfarct zones after reperfusion therapy in humans.

Although the mechanism is unknown, clinical trials have suggested that intravenous beta-adrenergic blockade may prevent early cardiac rupture after myocardial infarction. Previous studies have examined effects of beta-blockers on global left ventricular function after myocardial infarction; however, few data exist regarding their immediate effects on regional function or in patients after successful reperfusion. Therefore, 65 patients in whom thrombolysis with or without coronary angioplasty achieved reperfusion at 4.6 +/- 1.7 h from symptom onset were studied. Low osmolarity contrast ventriculograms were obtained immediately before and after administration of 15 mg of intravenous metoprolol (n = 54) or placebo (n = 11). Intravenous metoprolol immediately decreased heart rate (from 92 to 76 beats/min, p less than 0.0001), increased left ventricular diastolic volume (from 150 to 163 ml, p less than 0.001) and systolic volume (from 72 to 77 ml, p less than 0.0005) but did not change systolic and diastolic pressures. Although there was no difference in ejection fraction after metoprolol, centerline chord analysis revealed reduced noninfarct zone motion (from 0.41 to 0.12 SD/chord, p less than 0.05), improved infarct zone motion (from -3.1 to -2.9 SD/chord, p less than 0.01) and smaller circumferential extent of hypokinesia (from 30 to 27 chords, p less than 0.05). Patients with dyskinesia of the infarct zone had the most striking improvement in infarct zone wall motion. Because these changes occurred immediately after beta-blockade, they could not be attributed to myocardial salvage. No significant changes in heart rate, left ventricular volumes or regional wall motion were apparent in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Value and limitations of Doppler pressure half-time in quantifying mitral stenosis: a comparison with micromanometer catheter recordings.

The purpose of this study was to compare the Doppler and catheterization pressure half-time methods of estimating mitral valve area with valve areas obtained by the Gorlin equation in a group of patients with clinically significant mitral stenosis. Data were analyzed from 67 consecutive patients who were undergoing continuous-wave Doppler examination and catheterization with micromanometer catheters. Doppler pressure half-time was calculated as the interval between peak transmitral velocity and velocity divided by the square root of 2, as measured from the outer border of the spectral envelope. Doppler mitral valve area (MVA) was obtained with the equation: MVA = 220 divided by pressure half-time. For catheterization data, the pressure half-time was measured directly from simultaneously recorded left ventricular and left atrial pressure (18 patients) or pulmonary capillary wedge pressure (49 patients). The catheterization half-time was taken as the time required for the peak pressure gradient to fall to one half of the initial value. Calculations of the mitral valve area at catheterization were obtained by the Gorlin equation with pressure gradient and cardiac output determinations. Mitral valve area as determined by the Gorlin equation for all cases ranged from 0.4 to 2.0 (mean = 1.03 +/- 0.37) cm2. Linear regression analysis that compared cardiac catheterization and Doppler half-times yielded r = 0.68. For the subgroup of patients with sinus rhythm, the correlation improved to r = 0.76.(ABSTRACT TRUNCATED AT 250 WORDS)

Application of intravascular ultrasound for detection and quantitation of coronary atherosclerosis.

Although angiography is widely utilized to assess the extent and severity of coronary artery disease (CAD), arteriography yields only a silhouette of the vessel lumen. Coronary intravascular ultrasound supplements angiography by providing a tomographic perspective of lumen geometry and vessel wall structure. Intracoronary ultrasound can now be performed in vivo utilizing small, flexible probes capable of negotiating tortuous vessels. We have performed coronary ultrasound in more than 100 patients, including a group of normal subjects, with no serious complications. Measurements of coronary lumen dimensions by angiography and ultrasound correlated closely for normal vessels (r = 0.92) and for concentrically narrowed atherosclerotic vessels (r = 0.90). However, the correlation between angiography and ultrasound was only fair for eccentrically narrowed arteries (r = 0.79) and was poor following angioplasty (r = 0.30). Coronary artery wall motion was measured by intravascular ultrasound and demonstrated significant differences between normal arteries (18% lumen area change) and atherosclerotic vessels (11% change). Coronary ultrasound demonstrated important differences in the structure of normal and atherosclerotic vessel walls. Arteries in normal subjects exhibited a thin intimal leading-edge echo (mean 0.20 mm) and subadjacent sonolucent zone (mean 0.12 mm). Atherosclerotic vessels typically demonstrated increased thickness of both structures and often exhibited dense fibrocalcific plaques that shadowed underlying anatomy. These ultrasound abnormalities were often present at angiographically normal sites. Several limitations of coronary intravascular ultrasound were apparent, including echo 'dropout', distortions produced by non-coaxial imaging, and inability to image small or severely narrowed vessels. Coronary intravascular ultrasound holds great promise for the detection and quantification of CAD in the clinical setting.

Determination of coronary flow reserve by digital angiography: validation of a practical method not requiring power injection or electrocardiographic gating.

Although coronary flow reserve is a well established measure of the physiologic significance of atherosclerotic stenosis, cumbersome methodology has prevented its widespread clinical application. This study evaluated a new simplified method of measuring coronary flow reserve based on indicator-dilution analysis of hand-injected digital coronary arteriograms. In five dogs, the circumflex artery was instrumented with an angiographic catheter, an electromagnetic flow probe and a pneumatic occluder. For each of 18 stenoses of varying severity, arteriograms were obtained under basal conditions and during papaverine-induced hyperemia. A pair of background-corrected arterial time-density curves was generated for each stenosis by off-line computer analysis of the circumflex artery arteriograms. Coronary flow reserve was calculated from the measured areas of the time-density curves and the known volume of contrast medium used to produce each curve. Angiographic flow reserve ranged from 0.9 to 6.1 (mean 2.99), whereas electromagnetic flow reserve ranged from 0.7 to 6.9 (mean 3.02). Angiographic and electromagnetic measurements of coronary flow reserve correlated well (r = 0.86). This study establishes that indicator-dilution analysis of 30 frames/s digital coronary arteriography permits the accurate determination of coronary flow reserve. The technique described employs hand injection of small doses of radiographic contrast medium using conventional catheters, and should be readily applicable to the study of human coronary artery disease.

Mechanism of acute myocardial infarction in patients with prior coronary artery bypass grafting and therapeutic implications.

Although acute myocardial infarction (AMI) is usually due to thrombotic occlusion when involving a native coronary artery, the mechanism responsible for AMI in patients with previous coronary artery bypass grafting (CABG) is not well understood. Since knowledge of pathophysiology of AMI may alter subsequent management, angiograms obtained between 1 hour and 7 days of AMI (median 1 day) were reviewed in 50 patients greater than 1 year after CABG. The culprit vessel was identified by the presence of residual stenosis and/or thrombus in the vessel supplying the infarct zone or by reviewing previous angiograms. The infarct vessel was identified as a vein graft in 38 (76%) patients, the native vessel in 8 patients (16%) and could not be accurately determined in 4 patients (8%). Among the 38 vein grafts suspected as the infarct vessel, unequivocal angiographic evidence of residual thrombus (filling defect/persistent staining) was present in 31 (82%) and was greater than 2 cm in length in 15 patients. Successful reperfusion occurred in only 2 of 8 (25%) grafts after intravenous thrombolytic therapy. Intragraft thrombolysis with or without additional angioplasty was successful at restoring flow in 8 of 10 (80%) grafts. Data indicate that in patients who have undergone previous CABG, AMI is usually caused by thrombotic occlusion of a saphenous vein graft and that conventional intravenous thrombolytic therapy may be inadequate to restore flow. The large mass of thrombus and absent flow in the graft may require subselective drug infusion, a higher thrombolytic dose or a mechanical means of recanalization.

Removal of retained intracoronary percutaneous transluminal coronary angioplasty equipment by a percutaneous twin guidewire method.

Balloon rupture during percutaneous transluminal coronary angioplasty (PTCA) resulted in embolization of a guidewire-balloon fragment into the distal circumflex artery. Access to the circumflex was technically difficult because of aortic root dilation. The fragment was removed by inserting two PTCA guidewires into the artery and twisting them together to produce a helix. The helix propagated distally, entrapping the embolized fragment for removal. This report describes an unusual mode of failure for a balloon-on-a-wire dilating catheter and a new percutaneous removal technique that may be applied to retained catheter debris in small, inaccessible vessels.

Application of a new phased-array ultrasound imaging catheter in the assessment of vascular dimensions. In vivo comparison to cineangiography.

Tomographic imaging techniques such as ultrasound can provide important information in the evaluation of vascular anatomy. Recent technical advances have permitted fabrication of a small (1.83 mm), phased-array, intravascular ultrasonic imaging catheter capable of continuous real-time, cross-sectional imaging of blood vessels. We used this imaging catheter to compare intraluminal ultrasound with cineangiography in the measurement of vascular dimensions in animals and to assess the intraobserver and interobserver variability of the technique. Segmental deformation of vessel anatomy was produced by stenoses created with a tissue ligature or by balloon dilation. The mean value for measurements of vessel diameter was 5.6 mm by cineangiography and 5.7 mm by intravascular ultrasound. The correlation between cineangiography and ultrasound was close (r = 0.98). Mean cross-sectional area by angiography was 28.8 mm2 and 29.6 mm2 (r = 0.96) by ultrasound. Percent diameter reduction produced by the stenoses averaged 48.4% by cineangiography and 40.1% by ultrasound, and the two methods correlated closely (r = 0.89). Correlation between cineangiography and ultrasound for vessel diameter and area before balloon dilation was closer (r = 0.92 and 0.88) than after balloon dilation (r = 0.86 and 0.81). This difference reflected an increase in measured vessel eccentricity following balloon dilation. These data demonstrate that intravascular ultrasound is an accurate and reproducible method for measurement of vascular diameter and cross-sectional area in vivo. Intravascular ultrasound is capable of accurately identifying and quantifying segmental deformation of vascular dimensions produced by either stenoses or balloon dilation.