A randomized trial comparing the impact of a nonionic (iomeprol) versus an ionic (ioxaglate) low osmolar contrast medium on abrupt vessel closure and ischemic complications after coronary angioplasty

ObjectivesTo assess the effect of nonionic versus ionic contrast media on abrupt vessel closure and major ischemic complications after coronary angioplasty.BackgroundThere is a continuous debate about the “thrombogenic potential” of nonionic contrast media. The results of both in vitro and in vivo investigations are incongruent.MethodsWe prospectively evaluated the outcomes of 2,000 patients undergoing percutaneous transluminal coronary angioplasty (PTCA). According to a randomized, double-blind protocol, they received either iomeprol (nonionic; n = 1,001) or ioxaglate (ionic; n = 999). Intracoronary thrombus before PTCA was found more often in the iomeprol group (4.2% vs 2.7%, p = 0.04). No other significant differences between both groups were observed with regard to pre-PTCA clinical and angiographic characteristics.ResultsThe frequency of reocclusions necessitating repeat angioplasty occurring either in laboratory (2.9% with iomeprol and 3.0% with ioxaglate) or out of laboratory (3.1% vs 4.1%) was not significantly different. The rate of major ischemic complications was also comparable after both contrast media (emergency bypass surgery: 0.8% vs 0.7%, myocardial infarction: 1.8 vs 2.0%, cardiac death during hospital stay: 0.2% vs 0.2%). In the iomeprol group, more patients had dissections post-PTCA (30.2% vs 25.0%, p = 0.01) and more patients received intracoronary stents (31.6% vs 25.7%, p = 0.004). Allergic reactions requiring treatment occurred only in the ioxaglate group (0.0% vs 0.9%, p = 0.002).ConclusionsThe nonionic contrast medium was not associated with a higher rate of abrupt vessel closure requiring repeat angioplasty, or major ischemic events. These data suggest that nonionic contrast media do not increase the risk of thrombotic complications in patients undergoing coronary interventions.     

Effect of intracoronary injections of sonicated microbubbles on left ventricular contractility

Despite the recent interest in contrast-enhanced echocardiography as a means of defining myocardial perfusion, the effects of echo contrast agents on left ventricular (LV) contractility in humans remains poorly defined. This is particularly relevant because intracoronary injection of contrast agents used for angiographic visualization of coronary arteries produces significant alterations in LV hemodynamics. The relation of LV end-systolic wall stress (sigma es) to rate-corrected velocity of fiber shortening (Vcfc), a load-independent index of contractility, was studied in 7 patients undergoing elective coronary arteriography. Two-dimensional and targeted M-mode echocardiographic and central aortic pressure tracings were recorded during injections of standard volumes of angiographic (7 to 9 ml of nonsonicated Renografin-76) and echocardiographic (1.5 to 2.0 ml of sonicated Renografin-76) contrast agents into the left main coronary artery. The order in which agents were injected was randomly determined. Myocardial contractility was assessed under control conditions and 5 and 15 seconds after injection. Alterations in contractility relative to control were measured as the change in Vcfc after elimination of afterload (sigma es) as a confounding variable. An injection of Renografin-76 adequate for angiographic imaging of coronary artery anatomy resulted in a significant depression of LV contractility (p less than 0.001) in conjunction with a tendency toward increased afterload (p = 0.12); recovery occurred by 15 seconds after injection. The smaller amounts of sonicated Renografin-76 required to give adequate contrast enhancement of the myocardium did not alter LV contractile state or afterload.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of intracoronary ultrasound after high-pressure stent implantation

BACKGROUND: Poststent high-pressure balloon inflation has been shown to improve clinical outcomes. However, it is unknown whether intracoronary ultrasound (ICUS) provides additional clinical guidance after initial high-pressure balloon inflation is used during stent placement. Thus the purpose of this study was to determine if stent deployment techniques are improved with ICUS imaging despite an optimal angiographic result achieved with high-pressure balloon inflation. METHODS AND RESULTS: Prospective data were collected on 96 consecutive patients in whom 151 stents were deployed. Stents and high-pressure balloons were angiographically sized 1:1 by visual estimation. High-pressure (> or =12 atm in all cases) balloon inflations were continued until angiographic completion (<10% residual stenosis), after which index ICUS imaging was performed. Stent apposition, symmetry, and lumen dimensions were evaluated. An optimal ICUS result was defined as full apposition of the stent, symmetry ratio > or =0.80, and acute gain > or =0.80 of the reference lumen area. If inadequate ICUS results were found, further dilations with higher pressures or larger balloons and subsequent stent reevaluation with ICUS were performed. Sixty-nine (46%) stents required additional balloon inflations. Of these stents, 35 (23%) had initial acute gains that were <80% of the reference lumen area. Forty-six (30%) stents were found to have unapposed struts and 24 (16%) had a symmetry ratio <0.80. In patients requiring additional inflations, minimum stent area increased from 7.6 +/- 2.2 mm(2) to 9.2 +/- 2.4 mm(2) (P <.0001). Similarly, complete stent apposition improved from 33% to 68% of total stents (P <.0001). After initial ICUS, higher-pressure dilations were performed in 40 patients, whereas larger balloons greater than or equal to ICUS reference vessel diameter were used in 33 patients. Follow-up was obtained in 95 (99%) patients. The overall major adverse cardiac event rate at 6 months was 9.3%, which consisted of 8 target vessel revascularizations and 1 abrupt closure requiring repeat intervention. CONCLUSIONS: Even when poststent high-pressure balloon inflation achieves an optimal angiographic result, ICUS assists in optimizing acute gain, symmetry, and apposition of intracoronary stents in approximately 50% of patients. Moreover, ICUS guidance is associated with low rates for target vessel revascularization and major adverse cardiac events at 6-month follow-up.     

Variability in the measurement of intracoronary ultrasound images: implicatioNs for the identification of atherosclerotic plaque regression

Background and hypothesis: Serial coronary angiography cannot reliably detect the small changes in arterial dimensions. Measurement of arterial dimensions by intracoronary ultrasound (ICUS) may be a superior method to determine the extent of atherosclerotic burden since it directly images the diseased portion of the vessel. Methods: To quantify inter- and intraobserver variability of ICUS measurements, 27 images of atherosclerotic coronary lesions were measured by two study physicians and repeated 14 days later. Results: Interobserver correlation coefficients for external elastic lamina, lumen, and effective plaque area were 0.96, 0.99, and 0.91, respectively. Intraobserver correlation coefficients for external elastic lamina, lumen, and effective plaque area were 0.99, 0.99, and 0.97, respectively. To determine progression or regression in effective plaque area, a minimal difference of 2.77 mm² (which represents a 23% change in plaque area) is needed. Conclusions: Direct visualization of the extent of atherosclerosis by ICUS can be accomplished with a low degree of inter- and intraobserver variability. ICUS may be a preferable alternative to angiography in atherosclerosis regression trials.     

Angiographically undetected plaque in the left main coronary artery

The absence of angiographic findings despite significant coronary artery disease has been previously described. Possible explanations for the limitation of plaque detection by angiography include compensatory vessel enlargement in face of intracoronary plaque formation, the lack of reference segments in diffuse atherosclerosis as well as technical limitations. Intracoronary ultrasound (ICUS) imaging provides the possibility of direct plaque visualization. We studied angiographically normal left main coronary arteries (LMCA) in 72 patients prior to diagnostic angiography or therapeutic interventions using ICUS (30 MHz). ICUS images were continuously recorded and recalled from memory for morphometric analysis. Lumen area, plaque area and the total vessel area were determined by computer software. ICUS imaging revealed atherosclerotic plaque in 55 of the 72 patients with angiographically normal LMCA (76%). The average plaque area stenosis was 22±12% (range 3–44%). Total vessel area showed a significant direct correlation with plaque area, indicating compensation of coronary plaque formation. The average percent change in plaque area (difference between maximal and minimal plaque area within the LMCA) was 11±19%, indicating a diffuse pattern. Measurement of change in lumen area (difference between maximal and minimal lumen area within the LMCA) revealed an average value of 6±7%. Lumen area of the LMCA was 15.9±3.2 mm² in patients with and 17.2±1.9 mm² without atherosclerotic plaque (n.s.). Thus, the lack of angiographic changes despite advanced plaque formation in the LMCA could be explained by compensatory vessel enlargement and by diffuse distribution of plaque in the vessel; true lumen narrowings overlooked by angiography seem not to account for the failure of angiography to detect plaque.     

Adverse reactions of low osmolar non-ionic and ionic contrast media when used together or separately during percutaneous coronary intervention

BACKGROUND: Due to perceived advantages in the use of non-ionic contrast agents for diagnostic angiography and ionic agents for percutaneous coronary intervention (PCI), patients often receive various combinations of both types of agents. AIM: To assess potential adverse effects of non-ionic and ionic contrast media when used together or separately during percutaneous coronary intervention. METHODS: We retrospectively evaluated the outcomes of 532 patients undergoing percutaneous coronary intervention in our institution. Patients were divided into two groups: those that underwent diagnostic angiography and "follow on" PCI; and those that underwent "planned" PCI. The groups were subdivided on the basis of the use of the ionic agent ioxaglate or the non-ionic agent iopromide during PCI. The frequency of allergic reactions and major adverse cardiac events (MACE) were noted. RESULTS: With respect to the "follow on" group, allergic reactions occurred in 9 of 150 patients (6.0%) who received the combination of ioxaglate and iopromide versus 1 of 93 (1.1%) who only received iopromide (p=0.094). There was no difference with respect to MACE [6 (4.0%) ioxaglate and iopromide versus 4 (4.3%) iopromide alone, p=1.00]. In the "planned" group, 7 of 165 patients (4.2%) receiving ioxaglate had an allergic reaction as opposed 0.0% (0 of 124 patients) in the iopromide group (p=0.021). All contrast reactions were mild. The incidence of a MACE was similar in both groups [1 (0.6%) ioxaglate versus 2 (1.6%) iopromide, p=0.579]. The incidence of allergic reactions was similar if ioxaglate was used alone or in combination with iopromide (p=0.478). CONCLUSIONS: Whilst combining ionic and non-ionic contrast agents in the same procedure was not associated with any more adverse reactions than using an ionic contrast agent alone, the ionic contrast agent ioxaglate was associated with the majority of allergic reactions. With respect to choice of contrast agent, using the non-ionic agent iopromide alone for coronary intervention is associated with the lowest risk of an adverse event.     

Nonionic low-osmolar contrast media have no impact on major adverse cardiac events in patients undergoing coronary stenting with appropriate antiplatelet therapy.

The aim of this study was to assess the impact of two nonionic low-osmolar monomers (iopamidol and iopromide) and one ionic low-osmolar dimeric contrast medium (ioxaglate) on 30-day major adverse cardiac events in patients undergoing coronary interventions involving the use of new-generation stents and appropriate antiplatelet agents. Thirteen hundred and eight patients treated with stent implantation were randomized to receive ioxaglate (438 patients), iopamidol (442 patients), or iopromide (428 patients). Most of them (55%) had an acute coronary syndrome. Glycoprotein IIb/IIIa inhibitors were used in 37% of cases. All of the patients were on aspirin and ticlopidine for 1 month after the procedure. There was no significant between-group difference in the incidence of the primary composite endpoint of major adverse cardiac events 30 days after stenting (ioxaglate 3.6%; iopamidol 2.3%; iopromide 4.2%; P = 0.27). Adverse drug reactions were more frequent in the ioxaglate group (4.6% vs. 1.1% vs. 0.5%; P = 0.001). Multivariate analysis showed that intracoronary thrombus (P = 0.002), diabetes mellitus (P = 0.01), and postprocedure minimum lumen diameter (P = 0.04) independently correlated with an adverse outcome after 1 month. In conclusion, no significant differences in 30-day major ischemic complications were observed in this unselected population of patients undergoing coronary stenting who received ioxaglate, iopamidol, or iopromide. These data seem to suggest that the use of nonionic low-osmolar contrast media does not adversely affect stent patency.     

Risk of thrombosis during coronary angioplasty with low osmolality contrast media

Studies in vitro have suggested that nonionic low osmolar contrast agents produce an increase in thrombogenicity. To determine the incidence of thrombi related to the use of nonionic low osmolar contrast media during coronary angioplasty, a double-blind randomized study was performed in 100 patients. Medication before angioplasty included oral aspirin (250 mg/day) in all cases. At the beginning of the procedure, aspirin (250 mg) and heparin (10,000 U) were intravenously administered. During the procedure patients were randomly assigned to receive either an ionic low osmolar contrast agent ioxaglate (n = 50), or a nonionic low osmolar contrast media iohexol (n = 50). The presence of thrombus was evaluated on the angiogram and on the guidewire immediately after its retrieval from the patients. Clinical, angiographic and procedural variables were similar in the 2 randomized groups. Angiographic evidence of thrombus was observed in 1 patient (2%) assigned to ioxaglate and in 11 patients (22%) assigned to iohexol (p less than 0.005). One patient (2%) from the ioxaglate group and 6 patients (12%) from the iohexol group showed thrombotic residues on the guidewire (p = not significant). Three patients had acute myocardial infarction, 1 patient (2%) receiving ioxaglate and 2 patients (4%) iohexol (p = not significant). There were no deaths. Thus, compared with an ionic low osmolar contrast media ioxaglate, the nonionic low osmolar contrast agent iohexol increases the incidence of thrombus during coronary angioplasty.     

Comparison of immediate and in-hospital results of conventional balloon and perfusion balloon angioplasty using intracoronary ultrasound

Angiographic studies have demonstrated that perfusion balloon percutaneous transluminal coronary angioplasty (PTCA) may result in modestly improved luminal gains and fewer major dissections than conventional balloon PTCA. However, intracoronary ultrasound (ICUS), which is more sensitive than angiography in evaluating the incidence, extent, and severity of dissection, was not used. We randomized 48 patients with 54 coronary stenoses to conventional or perfusion balloon PTCA. Four 2-minute inflations were permitted with conventional balloon PTCA. Two 10-minute inflations were allowed with perfusion balloon PTCA. Quantitative coronary angiography and ICUS were performed before and after treatment. In-hospital clinical events were recorded. Conventional and perfusion balloon PTCA achieved similar improvements in lumen diameter (1.25+/-0.51 vs 1.28+/-0.51 mm) and reductions in percent stenosis (-45+/-21% vs -44+/-15%) by quantitative coronary angiography. Comparable gains in lumen diameter (0.62+/-0.39 vs 0.50+/-0.38 mm) and lumen area (2.70+/-1.96 vs 2.05+/-1.52 mm2) were observed on ICUS. Angiography demonstrated similar rates of any dissection (36% vs 21%) and major dissection (12% vs 7%). ICUS identified a similar incidence of any dissection (60% vs 76%) and type II dissection (52% vs 62%). The relative dissection area was also similar (9.2+/-5.6% vs 7.8+/-5.8%). One conventional balloon patient experienced postprocedural chest pain. No patient in either group died, or had myocardial infarction, abrupt closure, or urgent revascularization.     

Coronary artery distensibility in diabetic patients with simultaneous measurements of luminal area and intracoronary pressure: evidence of impaired reactivity to nitroglycerin.

OBJECTIVES: This study investigated whether noninsulin dependent diabetes mellitus (NIDDM) adversely affects the elastic properties of the coronary arteries in patients with coronary artery disease (CAD) and NIDDM. BACKGROUND: Attenuated vascular smooth muscle dilation to exogenous donors of nitric oxide, such as nitroglycerin, has been observed with forearm blood flow studies in patients with NIDDM. METHODS: Twenty patients with CAD and NIDDM (diabetics), and 20 patients with only CAD (nondiabetics) were evaluated. Intracoronary ultrasound (ICUS) imaging with simultaneous intracoronary pressure (P2) recordings were performed at the imaging site with 0.014 in fiber-optic high fidelity pressure monitoring wire. The same wire was used as guide wire for the ICUS catheter. Sites with less than 50% luminal stenosis by ICUS were studied. Recordings were done before and after 300 microg of intracoronary nitroglycerin (IC-NTG). Electrocardiographic tracings recorded simultaneously with ICUS images were used for timing. Systolic and diastolic cross-sectional lumen area (CSLA) and coronary artery distensibility (C-DIST) were measured, C-DIST = [(systolic CSLA-diastolic CSLA)/[(intracoronary pulse pressure) x (diastolic CSLA)]] x 1,000. RESULTS: Diabetics had smaller CSLA (diabetics = 8.6 +/- 0.6 mm2, nondiabetics = 11.5 +/- 0.5 mm2, p < 0.01). Although C-DIST was similar before IC-NTG in the two groups, it became significantly lower in diabetics after IC-NTG (diabetics C-DIST = 3.02 +/- 0.14 mm Hg(-1), nondiabetics C-DIST = 4.21 +/- 0.15 mm Hg(-1), p < 0.01). Degrees of circumference involved, total plaque burden and composition were similar in both groups. CONCLUSIONS: Noninsulin dependent diabetes mellitus reduces C-DIST after IC-NTG administration.     

Threshold parameters of left main coronary artery stem stenosis based on intracoronary ultrasound examination

INTRODUCTION: The left main coronary stem (LMS) provides blood supply to the left ventricle, and its stenosis is associated with serious clinical consequences. The accurate assessment of LMS stenosis determines appropriate treatment and long term prognosis. So far no criteria have been established to correctly estimate the magnitude of problematic lesions as indicated by quantitative angiography (QCA). AIM: An attempt to establish intracoronary ultrasound (ICUS) threshold values of significant LMS stenosis. METHODS: The studied group consisted of 197 patients (mean age 69.72+/-8.51) who underwent percutaneous coronary intervention (PCI) of the left coronary artery. Group 1 (G1) consisted of 99 patients who had LMS diameter reduction (%DS) of less than 30%. Group 2 (G2) consisted of 77 patients with %DS between 30% and 50%, and the remaining 21 patients with %DS higher than 50% were classified as Group 3 (G3). The quantitative angiography (QCA) analysis included lumen diameter (Ldmin) which was LMS lumen diameter at the most stenotic segment as well as LMS diameter reduction (%DS). The parameters that were analysed during ICUS study included maximum plaque burden (%) (Pbmax), minimal lumen area (LAmin) and lumen stenosis (%LS) calculated according to the formula: (LAmin/LAref) x 100%. Additionally, correlations between the corresponding parameters measured using QCA and ICUS were investigated. RESULTS: Both diagnostic techniques showed the most advanced degree of atherosclerosis in G3. All the G3 patients and 5 G2 patients had MLD values less than or equal to 2 mm. In G1 LAmin values exceeded 9 mm(2) in all patients, whereas among G2 patients 12 (15.5%) had LAmin lower than 6 mm(2), 29 pts. (37.66%) within the range of 6-9 mm(2) and in the remaining 36 pts. (46.75%) it exceeded 9 mm(2). In G3 LAmin values in 17 pts. (80.95%) did not exceed 6 mm(2) and in the remaining 4 pts. (19.05%) were slightly higher. Lumen reduction higher than 50% was noted in all G3 patients and 3 G2 patients (in all these 3 G2 patients LAmin values were lower than 6 mm(2)). All G3 pts. and 3 G2 pts. with LAmin value <6 mm(2) and %LS >50% had angina and a positive stress ECG test. All of these patients (n=24) underwent LMS stent implantation. CONCLUSIONS: 1. Minimal lumen diameter of LMS < or = 2 mm in quantitative angiography indicates a very high probability of significant stenosis of this vessel. 2. Ultrasound data analysis shows that besides LMS lumen area (<9 mm(2)) stenosis significance is determined by lumen reduction of more than 50%.     

The effects of ionic and nonionic radiographic contrast media on coronary hyperemia in patients during coronary angiography.

The purpose of this study was to compare the differential effects of ionic, high-osmolar meglumine diatrizoate; ionic, low-osmolar ioxaglate meglumine; and nonionic, low-osmolar iohexol (all radiographic contrast agents) on coronary blood flow velocity and hyperemic responses during diagnostic coronary angiography. Coronary flow velocity and arterial pressure were measured at baseline and during maximal hyperemia after contrast media were randomly injected (4 to 6 ml into left coronary artery) in 22 patients with the use of a Judkins-style 20 MHz Doppler-tipped angiographic catheter. Contrast media-induced hyperemic responses were compared to those induced with intracoronary nitroglycerin (200 micrograms) and papaverine (10 mg). There were no significant differences in systolic, diastolic, or mean arterial pressure measurements among the three contrast agents. The increase in mean coronary flow velocity during hyperemia was 118 +/- 93%, 133 +/- 73%, and 136 +/- 86% for iohexol, ioxaglate meglumine, and diatrizoate, respectively (p = NS among agents vs 264 +/- 109% for papaverine; p less than 0.05 for all). Coronary vasodilatory reserve (calculated as the ratio of hyperemic to basal mean flow velocity) was also similar among agents. It was comparable to the coronary vasodilatory reserve with nitroglycerin (2.1 +/- 1.0 to 2.2 +/- 1.1) and significantly less than that with papaverine (3.3 +/- 2.2, p less than 0.05). These data indicate that the clinical advantages of nonionic or low-osmolar contrast media are not mechanistically related to significant attenuation of the coronary hyperemic response.     

Myocardial risk area and peak gray level measurement by contrast echocardiography: effect of microbubble size and concentration, injection rate, and coronary vasodilation

Contrast agents were injected via the intracoronary route in eight dogs during two-dimensional echocardiographic imaging to determine the influence of microbubble size and concentration, injection rate, and coronary vasodilation on risk area and peak gray level measurement. At an injection rate at 13 cc/sec, the average background-subtracted peak gray level intensity of hand-agitated diatrizoate meglumine/diatrizoate sodium was significantly (p less than 0.01) higher than that of hand-agitated diatrizoate meglumine/diatrizoate sodium + 0.9% saline, sonicated diatrizoate meglumine/diatrizoate sodium, and sonicated 70% sorbitol. These differences were abolished by the use of 38 cc/sec injection rates and intracoronary injection of adenosine. Perfusion area determinations as assessed by planimetry were unaffected by the contrast agent used, the injection rate, or by intracoronary administration of adenosine. We conclude that risk area measurement by the ultrasound contrast technique is not affected by varying contrast agents, injection rates, or vasodilation. However, peak gray level intensity is variable among contrast agents and may result in variability of time-activity curve analysis.     

Retrospective image-based gating of intracoronary ultrasound images for improved quantitative analysis: the intelligate method.

Quantitative analysis of intracoronary ultrasound (ICUS) studies is performed on a series of tomographic cross-sectional ICUS images acquired during a motorized 0.5 mm/sec catheter pullback. Catheter displacement in the vascular lumen during the cardiac cycle causes an anatomically shuffled ICUS study, which results in a sawtooth-shaped appearance of the coronary segment in longitudinal reconstructed views in quantitative coronary ultrasound software packages. This hampers contour detection and leads to a laborious time-consuming semiquantitative analysis process that may produce inaccurate results. To solve these problems, in the past, online ECG-gated acquisition hardware has been applied. This article describes a novel image-based gating method called Intelligate, which features automatic retrospective selection of end-diastolic frames from videotaped or digitally stored ICUS studies. Our evaluation shows that there are no quantitative differences between analysis results of hardware ECG-gated and Intelligated ICUS studies.     

For left ventricular opacification and endocardial border definition: is it really important which contrast agent we use, or is it the imaging modality we choose?

AIMS: The purpose of this study was to prospectively compare the effect of three imaging modalities (fundamental, harmonics, and power harmonics) on left ventricular opacification and endocardial border definition with two different echo agents, Optison and Albunex. METHODS: A total of 84 patients who had suboptimal transthoracic images were studied with echo contrast agents Albunex (n=41) and Optison (n=43). Each contrast agent was examined with three different imaging modalities, fundamental, harmonics and power harmonics, respectively. Left ventricular opacification was obtained by videodensitometric analysis. Percentage of endocardial border visualization was determined by indexing circumference of visualized endocardium to total circumference. Variables were compared with respect to three imaging modalities between two different echo agents. RESULTS: Higher videointensities and higher percentages of endocardial visualization were achieved with Optison compared to Albunex with fundamental and harmonics. However, there was no significant difference between Optison and Albunex with respect to LV opacification and border visualization by power harmonics. CONCLUSION: These results indicate that left ventricular opacification and endocardial border visualization is significantly improved by using power harmonic imaging as compared to harmonics or fundamental imaging following both echo contrast agents. Furthermore, although Optison is clearly superior to Albunex in opacifying left ventricle, power harmonic imaging compensates for the less robust agent.     

Two-dimensional contrast echocardiography. I. In vitro development and quantitative analysis of echo contrast agents

To facilitate the passage of echo contrast agents through the microcirculation and the echocardiographic study of myocardial perfusion, ultrasonic energy (sonication) was employed to produce contrast agents consisting of relatively uniform, stable and small (less than 10 mu diameter) gaseous microbubbles suspended in liquid solutions. The size and persistence of the microbubbles was verified by light microscopy and an in vitro system were employed for comparative assessment of peak echo amplitude and echo persistence characteristics of various contrast agents. The study indicated that although a variety of hand-agitated and sonicated contrast agents provided satisfactory echo intensities, sonication was clearly superior to the hand-agitation method, because sonication produced smaller, more uniform and more stable microbubbles that may be suitable for myocardial contrast echocardiography. It is concluded that of the contrast agents examined, sonicated solutions of sorbitol (70%) and dextrose (70%) appeared to have particular potential because of the small sizes of the microbubbles (6 +/- 2 and 8 +/- 3 mu, respectively) and their prolonged in vitro persistence. The use of sonication to produce standardized, small and stable microbubbles should facilitate physiologic passage of the contrast agent through the capillary beds and allow two-dimensional imaging of the left heart myocardium during right-sided, aortic root, coronary sinus or intracoronary contrast injections.     

Single device approach to ultrasound-guided percutaneous transluminal coronary angioplasty and stenting: Initial experience with a combined intracoronary ultrasound/variable diameter balloon

We evaluated the use of both intracoronary ultrasound (ICUS) information and unique balloon characteristics provided by a combined ICUS/variable diameter balloon catheter during coronary interventions to achieve the maximal residual lumen using the least number of devices. In 47 patients, 64 coronary lesions were treated with either sequential percutaneous transluminal coronary angioplasty (PTCA) (n = 40) or stenting (primary [n = 17], secondary [n = 7]). The result after PTCA was judged satisfactory if the lumen cross sectional area (by ICUS) in the lesion exceeded 65% of the mean reference area. Stent implantation was judged according to revised MUSIC trial criteria. PTCA or stenting was successful in all 64 lesions using 47 combination devices and 10 conventional balloons (mean number of balloons per lesion: 0.90). PTCA group: diameter stenosis decreases from 78 ± 11 to 23 ± 13% following inflation at 10.3 ± 3.0 atm. ICUS lumen area was 4.6 ± 1.9 mm² (proximal reference: 7.4 ± 3.3 mm², distal reference: 5.7 ± 1.8 mm²) resulting in a residual area stenosis of 28 ± 15%. Stent group: diameter stenosis was reduced from 77 ± 14 to 10 ± 10% after stenting. ICUS defined minimal lumen area in the stent was 8.2 ± 2.2 mm² (proximal reference: 8.7 ± 2.6 mm², distal reference: 8.0 ± 2.2 mm²) resulting in a residual area stenosis of 7.2 ± 14.6%. No patient death, myocardial infarction, or emergency surgery occurred and only one target lesion required re-PTCA during hospitalization. In conclusion, use of a combined ICUS/variable diameter balloon catheter allows a single device strategy for ICUS-guided PTCA and stenting device strategy for ICUS-guided PTCA and stenting in the majority (84%) of unselected lesions. Cathet. Cardiovasc. Diagn. 40:393–399, 1997. © 1997 Wiley-Liss, Inc.     

Contrast-enhanced intravascular ultrasound: Validation of a new technique for delineation of the vessel wall boundary

Objectives. We evaluated a new technique for delineation of the vessel wall surface during intravascular ultrasound imaging using echogenic contrast agents.Background. Intravascular ultrasound is used for detection of complex vessel wall structures after catheter-based interventions; however, differentiation between the lumen and these wall structures can be difficult.Methods. In 12 anesthetized dogs, intracoronary ultrasound was performed during intracoronary bolus injection (3 and 6 ml) of different contrast agents (hand-agitated saline solution, standard iohexol, sonicated iohexol, hand-agitated iohexol, SHU 454, SHU 508). Contrast intensity was quantified by videodensitometry, and contrast homogeneity was assessed qualitatively (grade 0 to 3).Results. Peak contrast intensities for SHU 454 and SHU 508 (mean [± SD] 48 ± 9 and 36 ± 6 U, respectively) were higher compared with standard, sonicated or agitated iohexol (16 ± 3, 28 ± 7 and 20 ± 3 U, respectively) or with agitated saline solution (17 ± 4 U); intensities were higher for 6 ml compared with that for 3 ml. Contrast homogeneity was higher for SHU 508 (mean [± SD] 3.0 ± 0) and SHU 454 (2.7 ± 0.5) compared with the other agents (standard iohexol 1.2 ± 0.4, sonicated iohexol 2.0 ± 0.5, agitated iohexol 1.8 ± 0.6, agitated saline solution 1.0 ± 0.4). Exact delineation of the vessel wall surface was possible in 100% of SHU 508 and in 88% of SHU 454 injections compared with 13% of agitated iohexol and 8% of sonicated iohexol injections. Accurate surface delineation was never achieved with standard iohexol or agitated saline solution. Shadowing of parts of the vessel wall by contrast material occurred at peak intensity of 75% of SHU 508 and 46% of SHU 454 injections but not with the other agents. No adverse physiologic reactions were noted, except for transient negative inotropic effects after 6 ml of SHU 508.Conclusions. This preliminary study shows that delineation of the vessel wall boundary using echogenic contrast agents during intravascular ultrasound is safe and feasible. Because of higher contrast intensity and homogeneity, SHU 454 and SHU 508 are superior to other agents.     

Hemodynamic changes induced by cardiac angiography with ioxaglate: comparison with diatrizoate

The hemodynamic and electrocardiographic changes induced by left ventriculography and coronary arteriography with ioxaglate (a new low osmolality angiographic contrast agent) were characterized and compared with the changes induced by a commercial formulation of the commonly used angiographic contrast agent, diatrizoate (Renografin-76). Left ventriculography and coronary arteriography were performed in 25 patients utilizing ioxaglate and in another 25 patients utilizing diatrizoate. Both agents increased left ventricular end-diastolic pressure and decreased arteriovenous oxygen difference after left ventriculography, but the magnitude of the increase caused by ioxaglate was significantly less than that caused by diatrizoate (changes in left ventricular end-diastolic pressure was 5.3 +/- 1.3 mm Hg with ioxaglate and 9.5 +/- 1.5 mm Hg with diatrizoate [p less than 0.02] ). Change in arteriovenous oxygen difference was -0.33 +/- 0.19 ml/100 ml with ioxaglate and -0.85 +/- 0.13 ml/100 ml with diatrizoate (p less than 0.05). Both agents were well tolerated when used for coronary arteriography with no adverse events occurring in either group. Ioxaglate is a well tolerated cardiac angiographic contrast agent that produces less hemodynamic disturbance than diatrizoate. Accordingly, it may be particularly well suited to use in patients with impaired left ventricular function.     

Volumetric intracoronary ultrasound: Methods and validation

Intracoronary ultrasound (ICUS) not only allows visualization of the vessel lumen, it gives a unique view of the transmural components of the artery wall. Analysis of lumen and plaque volume is necessary for studying atherosclerotic disease progression or regression and the mechanisms of therapeutic coronary interventions. A real-time, ICUS pullback data acquisition scheme was developed to acquire calibrated, cardiac-gated volumetric image data sets. A semiautomated border detection scheme was implemented using dynamic programming. In phantoms, estimated area profiles were very reproducible as measured by the root-mean-square from the mean (3.8-5.9%). In phantom volume estimates, improved reproducibility (standard deviation = 1.2-3.6%) was obtained as positive and negative errors in area profiles were averaged out. Phantom volumes were also accurate when compared to true water displacement volume. The mean error ranged from ?2.59 to ?8.94%. When compared to quantitative single and biplane angiographic analysis, ICUS volumetric estimates tended to be superior to single plane analysis (error ?5.06 ± 2.48% vs ?9.96 ± 8.01%), but similar to optimal biplane analysis (error ?5.06 ± 2.48% vs ?6.34 ± 3.08%). In vivo reproducibility was assessed by performing multiple cardiac-gated pull-backs through experimentally induced stenosis. Over the length of the stenosis, excellent reproducibility of area profiles (± 5.9%) and volumes (± 1.9%) was obtained for cardiac-gated acquisitions. We conclude that volumetric ICUS provides accurate and reproducible estimates of lumen volume. Thus this technique may be of use in clinical trials where changes lumen volumes and vessel area profiles are of interest. © Wiley-Liss, Inc.