An integrated knowledge synthesis of regional ambient monitoring in Canada's oil sands

The desire to document and understand the cumulative implications of oil sands (OS) development in the ambient environment of northeastern Alberta has motivated increased investment and release of information in the past decade. Here, we summarize the knowledge presented in the theme-based review papers in this special series, including air, surface water, terrestrial biology, and Indigenous community-based monitoring in order to (1) consolidate knowledge gained to date, (2) highlight key commonalities and gaps, and (3) leverage this knowledge to assess the state of integration in environmental monitoring efforts in the OS region and suggest next steps. Among air, water, and land studies, the individual reviews identified a clear focus on describing stressors, including primarily (1) contaminant emission, transport, transformation, deposition, and exposure, and (2) landscape disturbance. These emphases are generally partitioned by theme; air and water studies focus heavily on chemical stressors, whereas terrestrial monitoring focuses on biological change and landscape disturbance. Causal attribution is often stated as a high priority objective across all themes. However, studies often rely on spatial proximity to attribute cause to industrial activity, leaving causal attribution potentially confounded by spatial covariance of both OS- and non-OS-related stressors in the region, and by the complexity of interacting pathways between sources of environmental change and ecological receptors. Geospatial and modeling approaches are common across themes and may represent clear integration opportunities, particularly to help inform investigation-of-cause, but are not a replacement for robust field monitoring designs. Cumulative effects assessment remains a common focus of regional monitoring, but is limited in the peer-reviewed literature, potentially reflecting a lack of integration among monitoring efforts beyond narrow integrated interpretations of results. Addressing this requires greater emphasis on a priori integrated data collection and integrated analyses focused on the main residual exposure pathways, such as atmospheric deposition. Integr Environ Assess Manag 2022;18:428-441. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Forest health effects due to atmospheric deposition: Findings from long-term forest health monitoring in the Athabasca Oil Sands Region

Oil sands developments release acidifying compounds (SO₂ and NO₂) with the potential for acidifying deposition and impacts to forest health. This article integrates the findings presented in the Oil Sands Forest Health Special Issue, which reports on the results of 20 years of forest health monitoring, and addresses the key questions asked by WBEA's Forest Health Monitoring (FHM) Program: 1) is there evidence of deposition affecting the environment?, 2) have there been changes in deposition or effects over time?, 3) do acid deposition levels require management intervention?, 4) what are major sources of deposited substances? and 5) how can the program be improved? Deposition of sulphur, nitrogen, base cations (BC), polycyclic aromatic compounds and trace elements decline exponentially with distance from sources. There is little evidence for acidification effects on forest soils or on understory plant communities or tree growth, but there is evidence of nitrogen accumulation in jack pine needles and fertilization effects on understory plant communities. Sulphur, BC and trace metal concentrations in lichens increased between 2008 and 2014. Source apportionment studies suggest fugitive dust in proximity to mining is a primary source of BC, trace element and organic compound deposition, and BC deposition may be neutralizing acidifying deposition. Sulphur accumulation in soils and nitrogen effects on vegetation may indicate early stages of acidification. Deposition estimates for sites close to emissions sources exceed proposed regulatory trigger levels, suggesting a detailed assessment of acidification risk close to the emission sources is warranted. However, there is no evidence of widespread acidification as suggested by recent modeling studies, likely due to high BC deposition. FHM Program evolution should include continued integration with modeling approaches, ongoing collection and assessment of monitoring data and testing for change over time, and addition of monitoring sites to fill gaps in regional coverage.

Culture and molecular-based profiles show shifts in bacterial communities of the upper respiratory tract that occur with age

The upper respiratory tract (URT) is a crucial site for host defense, as it is home to bacterial communities that both modulate host immune defense and serve as a reservoir of potential pathogens. Young children are at high risk of respiratory illness, yet the composition of their URT microbiota is not well understood. Microbial profiling of the respiratory tract has traditionally focused on culturing common respiratory pathogens, whereas recent culture-independent microbiome profiling can only report the relative abundance of bacterial populations. In the current study, we used both molecular profiling of the bacterial 16S rRNA gene and laboratory culture to examine the bacterial diversity from the oropharynx and nasopharynx of 51 healthy children with a median age of 1.1 years (range 1-4.5 years) along with 19 accompanying parents. The resulting profiles suggest that in young children the nasopharyngeal microbiota, much like the gastrointestinal tract microbiome, changes from an immature state, where it is colonized by a few dominant taxa, to a more diverse state as it matures to resemble the adult microbiota. Importantly, this difference in bacterial diversity between adults and children accompanies a change in bacterial load of three orders of magnitude. This indicates that the bacterial communities in the nasopharynx of young children have a fundamentally different structure from those in adults and suggests that maturation of this community occurs sometime during the first few years of life, a period that includes ages at which children are at the highest risk for respiratory disease.

Hyperspectral cathodoluminescence imaging and analysis extending from ultraviolet to near infrared

The measurement of near-infrared (NIR) cathodoluminescence (CL) with sufficient sensitivity to allow full spectral mapping has been investigated through the application of optimized grating spectrometers that allow the ultraviolet (UV), visible, and NIR CL spectra to be measured simultaneously. Two optical spectrometers have been integrated into an electron microprobe, allowing simultaneous collection of hyperspectral CL (UV-NIR), characteristic X-rays, and electron signals. Combined hyperspectral CL spectra collected from two natural apatite (Ca5[PO4]3[OH,F]) samples from Wilberforce (Ontario, Canada) and Durango (Mexico) were qualitatively analyzed to identify the emission centers and then deconvoluted pixel-by-pixel using least-squares fitting to produce a series of ion-resolved CL intensity maps. Preliminary investigation of apatite has shown strong NIR emissions associated primarily with the rare-earth element Nd. Details of growth and alteration were revealed in the NIR that were not discernable with electron-induced X-ray mapping. Intense emission centers from Nd3+ and Sm3+ were observed in the spectra from both apatites, along with minor emissions from other 3+ rare-earth elements. Quantitative electron probe microanalysis was performed on points within the mapped area of the Durango apatite to produce a calibration line relating cathodoluminescent intensity of the fitted peak centered at 1,073 nm (1.156 eV) to the Nd concentration.

Integration of transcriptional inputs at promoters of the arabinose catabolic pathway

BACKGROUND

Most modelling efforts of transcriptional networks involve estimations of in vivo concentrations of components, binding affinities and reaction rates, derived from in vitro biochemical assays. These assays are difficult and in vitro measurements may not approximate actual in vivo conditions. Alternatively, changes in transcription factor activity can be estimated by using partially specified models which estimate the "hidden functions" of transcription factor concentration changes; however, non-unique solutions are a potential problem. We have applied a synthetic biology approach to develop reporters that are capable of measuring transcription factor activity in vivo in real time. These synthetic reporters are comprised of a constitutive promoter with an operator site for the specific transcription factor immediately downstream. Thus, increasing transcription factor activity is measured as repression of expression of the transcription factor reporter. Measuring repression instead of activation avoids the complications of non-linear interactions between the transcription factor and RNA polymerase which differs at each promoter.

RESULTS

Using these reporters, we show that a simple model is capable of determining the rules of integration for multiple transcriptional inputs at the four promoters of the arabinose catabolic pathway. Furthermore, we show that despite the complex and non-linear changes in cAMP-CRP activity in vivo during diauxic shift, the synthetic transcription factor reporters are capable of measuring real-time changes in transcription factor activity, and the simple model is capable of predicting the dynamic behaviour of the catabolic promoters.

CONCLUSIONS

Using a synthetic biology approach we show that the in vivo activity of transcription factors can be quantified without the need for measuring intracellular concentrations, binding affinities and reaction rates. Using measured transcription factor activity we show how different promoters can integrate common transcriptional inputs, resulting in distinct expression patterns. The data collected show that cAMP levels in vivo are dynamic and agree with observations showing that cAMP levels show a transient pulse during diauxic shift.

Individuality in bacteria

While traditionally microbiologists have examined bacterial behavior averaged over large populations, increasingly we are becoming aware that bacterial populations can be composed of phenotypically diverse individuals generated by a variety of mechanisms. Though the results of different mechanisms, the phenomena of bistability, persistence, variation in chemotactic response, and phase and antigenic variation are all strategies to develop population-level diversity. The understanding of individuality in bacteria requires an appreciation of their environmental and ecological context, and thus evolutionary theory regarding adaptations to time-variable environments is becoming more applicable to these problems. In particular, the application of game and information theory to bacterial individuality has addressed some interesting problems of bacterial behavior. In this review we discuss the mechanisms of generating population-level variability, and the application of evolutionary theory to problems of individuality in bacteria.

Predictive value of dobutamine stress echocardiography for coronary artery disease detection in liver transplant candidates

Patients with obstructive coronary artery disease (CAD) undergoing orthotopic liver transplantation (OLT) are at increased risk of poor outcomes. The accuracy of dobutamine stress echocardiography (DSE) to detect obstructive CAD is not well established in this population. We retrospectively identified patients with end-stage liver disease who underwent both DSE and coronary angiography as part of risk stratification prior to OLT. One hundred and five patients had both DSE and angiography, of whom 14 had known CAD and 27 failed to reach target heart rate during DSE. Among the remaining 64 patients (45 men; average age 61 +/- 8 years) DSE had a low sensitivity (13%), high specificity (85%), low positive predictive value (PPV) (22%) and intermediate negative predictive value (NPV) (75%) for obstructive CAD. DSE as a screening test for obstructive CAD in OLT candidates has a poor sensitivity. The frequent chronotropic incompetence and low sensitivity in patients who achieve target heart rate, even in those with multiple cardiovascular disease risk factors, suggest that alternative or additional methods of risk stratification are necessary.

Impact of intracoronary aspiration thrombectomy during primary angioplasty on left ventricular remodelling in patients with anterior ST elevation myocardial infarction

OBJECTIVE

To evaluate prospectively the impact on left ventricular (LV) remodelling of an intracoronary aspiration thrombectomy device as adjunctive therapy in primary percutaneous coronary intervention (PCI) in patients with anterior ST elevation myocardial infarction (STEMI).

METHODS

76 consecutive patients with anterior STEMI (65.3 (11.2) years, 48 men) were randomly assigned to intracoronary thrombectomy and stent placement (n = 38) or to conventional stenting (n = 38) of the infarct related artery. Each patient underwent transthoracic echocardiography immediately after PCI and at six months. At the time of echocardiographic control, major adverse cardiovascular events (MACE) in terms of death, new onset of myocardial infarction, and hospitalisation for heart failure were also evaluated.

RESULTS

After a successful primary PCI, patients in the thrombectomy group achieved a higher rate of post-procedure myocardial blush grade 3 (36.8% v 13.1%, p = 0.03) and effective ST segment resolution at 90 minutes (81.6% v 55.3%, p = 0.02). Six months after the index intervention, 19 patients (26.8%) developed LV dilatation, defined as an increase in end diastolic volume (EDV) >or= 20%: 15 in the conventional group and four in the thrombectomy group (p = 0.006). Accordingly, at six months patients treated conventionally had significantly higher end systolic volumes (82 (7.7) ml v 75.3 (4.9) ml, p < 0.0001) and EDV (152.5 (18.1) ml v 138.1 (10.7) ml, p < 0.0001) than patients treated with thrombectomy. No differences in cumulative MACE were observed (10.5% in the conventional group v 8.6% in the thrombectomy group, not significant).

CONCLUSION

Compared with conventional stenting, adjunctive aspiration thrombectomy in successful primary PCI seems to be associated with a significantly lower incidence of LV remodelling at six months in patients with anterior STEMI.

450 million years of hemostasis

In mammalian blood coagulation, five proteases (factor VII [FVII]; factor IX [FIX]; factor X [FX]; protein C [PC] and prothrombin [PT]) act with five cofactors (tissue factor [TF]; factor V [FV]; factor VIII [FVIII]; thrombomodulin and protein S) to control the generation of fibrin. Biochemical evidence, molecular cloning data and comparative sequence analysis support the existence of all components of this network in all jawed vertebrates, and strongly suggest that it evolved before the divergence of teleosts over 430 million years ago. Phylogenetic analysis of the amino acid sequences of the Gla-EGF1-EGF2-SP domain serine proteases (FVII, FIX, FX, PC) and the A domain-containing cofactors (FV and FVIII) strongly supports the evolution of the blood coagulation network through two rounds of gene duplication, and supports the hypothesis that vertebrate evolution benefited from two global genome duplications. The jawless vertebrates (hagfish and lamprey) that diverged over 450 million years ago have a blood coagulation network involving TF, PT and fibrinogen. Preliminary evidence indicates that they may have a smaller complement of Gla-EGF1-EGF2-SP domain proteins, suggesting the existence of a 'primitive' coagulation system in jawless vertebrates.

Clinical pharmacology of higher dose eptifibatide in percutaneous coronary intervention (the PRIDE study)

This study describes the dose-exploration phase of the PRIDE trial, an investigation of the clinical pharmacology of higher dose eptifibatide in patients who underwent elective percutaneous coronary intervention (PCI). Outcomes of treatment with the platelet glycoprotein IIb/IIIa inhibitors were dependent upon proper dosing selection. In this multicenter, placebo-controlled clinical study, 127 patients were randomized 1:1:2:2 into 1 of the following treatment groups: placebo; eptifibatide as a 135 microg/kg bolus followed by a 0.75 microg/kg/min infusion; eptifibatide as a 180 microg/kg bolus with a 2.0 microg/kg/min infusion; or eptifibatide as a 250 microg/kg bolus with a 3.0 microg/kg/min infusion. Light transmission aggregometry was used to determine platelet aggregation in response to 20 microM adenosine diphosphate, and platelet receptor occupancy was also determined. Eptifibatide exhibited linear pharmacokinetics over the dose range studied. Inhibition of platelet aggregation was greater in samples collected in sodium citrate compared with those collected in D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone. The 180/2.0 dosing regimen achieved 90% inhibition of platelet aggregation immediately (5 minutes) and at steady state (8 to 24 hours). At 1 hour, mean inhibition of platelet aggregation was 80%. Eptifibatide exhibited dose-dependent pharmacodynamics that were dependent upon choice of anticoagulant. A 180 microg/kg bolus followed by a 2.0 microg/kg/min infusion at steady state achieved >80% inhibition of platelet aggregation. With the single-bolus regimen, however, there was an early loss of the inhibition of platelet aggregation before steady state was reached. Additional dose-exploration studies may further optimize eptifibatide dosing.

Predictors of long-term outcomes following direct percutaneous coronary intervention for acute myocardial infarction

To determine predictors of a long-term major adverse cardiac event (MACE) in unselected patients undergoing direct percutaneous coronary intervention (PCI), 274 consecutive patients presenting within 12 hours of ST-segment elevation acute myocardial infarction (AMI) were evaluated. No patient with ST-segment elevation AMI received intravenous thrombolytic drugs. Chest pain to balloon time was 3.8 hours (range 2.5 to 6.9). percutaneous transluminal coronary angioplasty was successful in 95% of patients. Abciximab was administered to 69% of patients, stents were deployed in 53%, and 17% underwent only catheterization. In-hospital events were death (7%), abrupt closure (2%), emergent coronary artery bypass grafting (CABG) (5%), repeat PCI (3%), and recurrent myocardial infarction (1%). In patients undergoing direct PCI (n = 227), the in-hospital event rate was death 5.3%, abrupt closure 2.2%, emergency CABG 0.9%, repeat PCI 3.1%, and repeat myocardial infarction 1.3%. Median time to last follow-up or death was 20 months (range 11 to 34), and to any event, 0.3 months (range 0.03 to 24.0). Postdischarge MACE included death (5%), AMI (4%), repeat PCI (8%), CABG (9%), and stroke (0.7%). Among those undergoing direct PCI (n = 227), 10% died, 3.5% had a repeat AMI, 9% had a repeat PCI, 5% had CABG, and 1% had a stroke at long-term follow-up. At long-term follow-up, 75% were event free. Multivariate predictors were (hazard ratio [95% confidence interval (CI)]): abciximab use 0.6 (95% CI 0.43 to 0.95), Killip class 2.2 (95% CI 1.1 to 4.4), and number of narrowed coronary arteries 1.7 (95% CI 1.4 to 2.2). In this unselected consecutive series of patients presenting with ST-segment elevation AMI, direct PCI was associated with sustained long-term efficacy. Outcomes were predicted by cardiac impairment at presentation and number of narrowed coronary arteries. MACE is not related to device selection but is significantly improved with abciximab.

In-hospital and long-term outcomes of patients with acute myocardial infarction undergoing direct angioplasty during regular and after hours

Off-hours presentation resulted in a significant increase in the onset of pain to balloon inflation time (approximately 1.3 hours) as well as the emergency room to balloon inflation time (approximately 54 minutes). However, this delay to reperfusion did not result in a difference in clinical outcomes (in-hospital or long-term) in patients undergoing direct percutaneous transluminal coronary angioplasty within 12 hours of the onset of acute myocardial infarction.

Adjunctive therapies in the cath lab. Successful thrombolysis using the combination of tissue plasminogen activator and abciximab in an adult with Kawasaki's disease

Kawasaki's disease is an acute systemic vasculitic syndrome that primarily affects children. Coronary aneurysms are common vasculitic sequelae of Kawasaki's disease. Intracoronary thrombosis and embolization are potential consequences of coronary aneurysms. We describe our experience of successful thrombolysis using the combination of reduced-dose intravenous tissue plasminogen activator and abciximab as described in the Thrombolysis in Myocardial Infarction 14 trial (TIMI 14) to treat a patient found to have intracoronary thrombus at the site of aneurysm formation due to Kawasaki's disease.

Excimer laser facilitated percutaneous coronary intervention of a nondilatable coronary stent

A patient is described in which excimer laser percutaneous coronary intervention is performed inside a suboptimally expanded stent due to nondilatable calcified plaque. The use of excimer laser facilitated full expansion of the stent with a balloon.

Resource utilization and clinical outcomes of coronary stenting: a comparison of intravascular ultrasound and angiographical guided stent implantation

BACKGROUND

Intravascular ultrasound (IVUS) guided stent implantation studies have demonstrated that inadequate stent implantation can occur despite achieving an optimal angiographic result. Furthermore, IVUS-guided stent implantation has been shown to improve lesional acute gain. However, it is unknown whether the use of IVUS guidance during stent implantation is associated with improved acute and long-term clinical outcomes. Moreover, the additional procedural cost and time incurred with the use of IVUS-directed stent implantation has not been evaluated. Thus the purpose of this study was to determine whether IVUS-guided stent implantation is associated with improved clinical outcomes compared with angiographically guided stent implantation and to evaluate the difference in resource utilization between these respective stent deployment strategies.

METHODS

Data were collected on 278 consecutive patients in whom 455 stents were deployed in native coronary arteries. High-pressure (> or = 12 atm) balloon inflations were performed until an optimal angiographic result was obtained. In the angiographically guided group, no IVUS imaging was performed. In the IVUS-guided group, IVUS imaging and additional interventions were performed attempting to achieve full apposition, absence of edge tear, and acute gain (lesion lumen area: distal reference lumen area) > or = 0.8 in subsequent IVUS imaging. Total procedure time, fluoroscopy time, contrast media volume, number of balloons, stents, guidewires, guide catheters, and procedural cost were calculated. In hospital abrupt closure rate and 6-month major adverse cardiovascular events (cardiac death, myocardial infarction, target vessel revascularization) rate were obtained.

RESULTS

A total of 178 patients underwent IVUS-guided stent placement and 100 patients underwent angiographically guided stent implantation. There was no significant difference in procedure time (107 +/- 49 vs 100 +/- 50 minutes, P = .22), fluoroscopy time (33 +/- 24 vs 30 +/- 18 minutes, P = .36), contrast volume (411 +/- 157 vs 386 +/- 181 mL, P = .23), guide catheters (1.3 +/- 0.8 vs 1.3 +/- 0.6, P = .69), guidewires (1.6 +/- 1.2 vs 1.6 +/- 1.0, P = .99), balloons (2.4 +/- 1.0 vs 2.3 +/- 1.3, P = .58), and stents (1.7 +/- 0.9 vs 1.6 +/- 0.9, P = .42). Intraprocedural cost was significantly higher in the IVUS-guided group, $4142 +/- 1547 verus $3635 +/- 1949 (P = .03), which was primarily related to the cost of the IVUS catheter. However, the in-hospital acute vessel closure rate was significantly lower in the IVUS-guided group, 0.6% versus 4% (P = .04). There was a trend toward lower target vessel revascularization rate in the IVUS-guided group (11% vs 19%, P = .08). By multivariate analysis IVUS use was demonstrated to be an independent negative predictor of cardiac death, myocardial infarction, repeat revascularization, and abrupt stent closure with a relative risk of 0.49 (95% confidence interval of 0.25 to 0.98), and P = .04.

CONCLUSIONS

The use of IVUS guidance during stent implantation does not significantly increase procedure time, fluoroscopy exposure, contrast volume, or device utilization. Furthermore, despite the increase in procedural cost, IVUS-guided stent implantation is associated with a significant decrease in the in-hospital abrupt closure rate and a trend toward a lower 6-month target vessel revascularization.

Visualization of discrete microinfarction after percutaneous coronary intervention associated with mild creatine kinase-MB elevation

BACKGROUND

Mild elevations in creatine kinase-MB (CK-MB) are common after successful percutaneous coronary interventions and are associated with future adverse cardiac events. The mechanism for CK-MB release remains unclear. A new contrast-enhanced MRI technique allows direct visualization of myonecrosis.

METHODS AND RESULTS

Fourteen patients without prior infarction underwent cine and contrast-enhanced MRI after successful coronary stenting; 9 patients had procedure-related CK-MB elevation, and 5 did not (negative controls). The mean age of all patients was 61 years, 36% had diabetes, 43% had multivessel coronary artery disease, and all had a normal ejection fraction. Twelve patients (86%) received an intravenous glycoprotein IIb/IIIa inhibitor; none underwent atherectomy, and all had final TIMI 3 flow. Of the 9 patients with CK-MB elevation, 5 had a minor side branch occlusion during stenting, 2 had transient ECG changes, and none developed Q-waves. The median CK-MB was 21 ng/mL (range, 12 to 93 ng/mL), which is 2.3x the upper limit of normal. Contrast-enhanced MRI demonstrated discrete regions of hyperenhancement within the target vessel perfusion territory in all 9 patients. Only one developed a new wall motion abnormality. The median estimated mass of myonecrosis was 2.0 g (range, 0.7 to 12.2 g), or 1.5% of left ventricular mass (range, 0.4% to 6.0%). Hyperenhancement persisted in 5 of the 6 who underwent a repeat MRI at 3 to 12 months. No control patient had hyperenhancement.

CONCLUSIONS

Contrast-enhanced MRI provides an anatomical correlate to biochemical evidence of procedure-related myocardial injury, despite the lack of ECG changes or wall motion abnormalities. Mild elevation of CK-MB after percutaneous coronary intervention is the result of discrete microinfarction.

Thrombotic thrombocytopenic purpura associated with clopidogrel

BACKGROUND

The antiplatelet drug clopidogrel is a new thienopyridine derivative whose mechanism of action and chemical structure are similar to those of ticlopidine. The estimated incidence of ticlopidine-associated thrombotic thrombocytopenic purpura is 1 per 1600 to 5000 patients treated, whereas no clopidogrel-associated cases were observed among 20,000 closely monitored patients treated in phase 3 clinical trials and cohort studies. Because of the association between ticlopidine use and thrombotic thrombocytopenic purpura and other adverse effects, clopidogrel has largely replaced ticlopidine in clinical practice. More than 3 million patients have received clopidogrel. We report the clinical and laboratory findings in 11 patients in whom thrombotic thrombocytopenic purpura developed during or soon after treatment with clopidogrel.

METHODS

The 11 patients were identified by active surveillance by the medical directors of blood banks (3 patients), hematologists (6), and the manufacturer of clopidogrel (2).

RESULTS

Ten of the 11 patients received clopidogrel for 14 days or less before the onset of thrombotic thrombocytopenic purpura. Although 10 of the 11 patients had a response to plasma exchange, 2 required 20 or more exchanges before clinical improvement occurred, and 2 had relapses while not receiving clopidogrel. One patient died despite undergoing plasma exchange soon after diagnosis.

CONCLUSIONS

Thrombotic thrombocytopenic purpura can occur after the initiation of clopidogrel therapy, often within the first two weeks of treatment. Physicians should be aware of the possibility of this syndrome when initiating clopidogrel treatment.

Randomized trial of contrast media utilization in high-risk PTCA: the COURT trial

BACKGROUND

Previous in vitro and in vivo studies have suggested an association between thrombus-related events and type of contrast media. Low osmolar contrast agents appear to improve the safety of diagnostic and coronary artery interventional procedures. However, no data are available on PTCA outcomes with an isosmolar contrast agent.

METHODS AND RESULTS

A multicenter prospective randomized double-blind trial was performed in 856 high-risk patients undergoing coronary artery intervention. The objective was to compare the isosmolar nonionic dimer iodixanol (n=405) with the low osmolar ionic agent ioxaglate (n=410). A composite variable of in-hospital major adverse clinical events (MACE) was the primary end point. A secondary objective was to evaluate major angiographic and procedural events during and after PTCA. The composite in-hospital primary end point was less frequent in those receiving iodixanol compared with those receiving ioxaglate (5.4% versus 9.5%, respectively; P=0.027). Core laboratory defined angiographic success was more frequent in patients receiving iodixanol (92.2% versus 85. 9% for ioxaglate, P=0.004). There was a trend toward lower total clinical events at 30 days in patients randomized to iodixanol (9.1% versus 13.2% for ioxaglate, P=0.07). Multivariate predictors of in-hospital MACE were use of ioxaglate (P=0.01) and treatment of a de novo lesion (P=0.03).

CONCLUSIONS

In this contemporary prospective multicenter trial of PTCA in the setting of acute coronary syndromes, there was a low incidence of in-hospital clinical events for both treatment groups. The cohort receiving the nonionic dimer iodixanol experienced a 45% reduction in in-hospital MACE when compared with the cohort receiving ioxaglate.

Exacerbation of radiocontrast nephrotoxicity by endothelin receptor antagonism

BACKGROUND

Endothelin is a potent vasoconstrictor that has been implicated in the pathogenesis of radiocontrast nephrotoxicity. Endothelin antagonists may reduce the renal hemodynamic abnormalities following radiocontrast administration.

METHODS

One hundred fifty-eight patients with chronic renal insufficiency [mean serum creatinine +/- SD = 2.7 +/- 1.0 mg/dL (242. 3 to +/- 92.8 micromol/L)] and undergoing cardiac angiography were randomized to receive either a mixed endothelin A and B receptor antagonist, SB 290670, or placebo. All patients received intravenous hydration with 0.45% saline before and after radiocontrast administration. Serum creatinine concentrations were measured at baseline, 24 hours, 48 hours, and 3 to 5 days after radiocontrast administration. The primary end point was the mean change in serum creatinine concentration from baseline at 48 hours; the secondary end point was the incidence of radiocontrast nephrotoxicity, defined as an increase in serum creatinine of > or =0.5 mg/dL (44 micromol/L) or > or = 25% from baseline within 48 hours of radiocontrast administration.

RESULTS

The mean increase in serum creatinine 48 hours after angiography was higher in the SB 209670 group [0.7 +/- 0. 7 mg/dL (63.5 +/- 58.6 micromol/L)] than in the placebo group [0.4 +/- 0.6 mg/dL (33.6 +/- 55.1 micromol/L), P = 0.002]. The incidence of radiocontrast nephrotoxicity was also higher in the SB 209670 group (56%) compared with placebo (29%, P = 0.002). This negative effect of SB 209670 was apparent in both diabetic and nondiabetic patients. Adverse effects, especially hypotension or decreased blood pressure, were more common in the SB 209670 group.

CONCLUSIONS

In patients with chronic renal insufficiency who were undergoing cardiac angiography, endothelin receptor antagonism with SB 209670 and intravenous hydration exacerbate radiocontrast nephrotoxicity compared with hydration alone.

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.

Effect of variability in the interpretation of coronary angiograms on the appropriateness of use of coronary revascularization procedures

BACKGROUND

Evidence from numerous studies of coronary angiography show differences between observers' assessments of 15% to 45%. The implication of this variation is serious: If readings are erroneous, some patients will undergo revascularization procedures unnecessarily and others will be denied an essential treatment. We evaluated the variation in interpretation of angiograms and its potential effect on appropriateness of use of revascularization procedures.

METHODS AND RESULTS

Angiograms of 308 randomly selected patients previously studied for appropriateness of angiography, coronary artery bypass grafting (CABG), and percutaneous transluminal coronary angioplasty (PTCA) were interpreted by a blinded panel of 3 experienced angiographers and compared with the original interpretations. The potential effect on differences on the appropriateness of revascularization was assessed by use of the RAND criteria. Technical deficiencies were found in 52% of cases. Panel readings tended to show less significant disease (none in 16% of vessels previously read as showing significant disease), less severity of stenosis (43% lower, 6% higher), and lower extent of disease (23% less, 6% more). The classification of CABG changed from necessary/appropriate to uncertain/inappropriate for 17% to 33% of cases when individual ratings were replaced by panel readings.

CONCLUSIONS

The general level of technical quality of coronary angiography is unsatisfactory. Variation in the interpretation of angiograms was substantial in all measures and tended to be higher in individual than in panel readings. The effect was to lead to a potential overestimation of appropriateness of use of CABG by 17% and of PTCA by 10%. These findings indicate the need for increased attention to the technical quality of studies and an independent second reading for angiograms before recommending revascularization.

Thrombotic thrombocytopenic purpura associated with ticlopidine in the setting of coronary artery stents and stroke prevention

BACKGROUND

One of the most unusual causes of thrombotic thrombocytopenic purpura (TTP), a life-threatening disease, is ticlopidine hydrochloride, an antiplatelet agent used to prevent strokes in high-risk populations or following coronary artery stent placement. Recently, Hoffman-LaRoche Pharmaceuticals, following reports of 20 deaths from ticlopidine-associated TTP, updated the information about the hematologic adverse effects of the drug.

OBJECTIVES

To review our recent findings on ticlopidine-associated hematologic toxic effects, which served as the impetus for the revised warnings, and to discuss the implications of these findings.

METHODS

Data were obtained from the Food and Drug Administration's MedWatch program, published phase 3 clinical trials and case reports, hematologists, and plasmapheresis centers.

RESULTS

No cases of TTP have been reported in phase 3 ticlopidine trials. In contrast, postmarketing surveillance has identified serious adverse drug reactions to ticlopidine, resulting in 259 deaths, with TTP accounting for 40 of these deaths. Detailed information was available on 98 cases of ticlopidine-associated TTP. Compared with 42 patients in the coronary artery stent setting, 56 patients with ticlopidine-associated TTP in the stroke prevention setting were more likely to be women (62.5% vs 28.6%; P = .01). Before the onset of TTP in patients receiving stroke prevention therapy and patients with stent placement, ticlopidine had been used for less than 2 weeks in 5.4% and 2.4%, between 2 and 3 weeks in 17.9% and 21.4%, between 3 and 4 weeks in 30.4% and 38.1%, and between 4 and 12 weeks in 46.4% and 38.1%, respectively. Death occurred in almost 60% of all patients not receiving plasmapheresis compared with 21.9% of patients receiving plasmapheresis for stroke prevention and 14.3% of patients receiving plasmapheresis in the stent setting.

CONCLUSIONS

Use of ticlopidine requires frequent physician visits and laboratory tests for at least 3 months in the stroke prevention setting, while, with short-term use in the coronary artery stent setting, adverse events are less likely to occur. These factors, as well as competition from clopidogrel bisulfate, a new antiplatelet agent, potentially limit the feasibility of ticlopidine as a stroke prevention agent, while having less impact on its use following coronary artery stent placement.

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.

Internal mammary artery graft angioplasty: acute and long-term outcome

Secondary to the low attrition rate of internal mammary artery grafts, limited data are available on the clinical and angiographic outcome of patients who have undergone balloon angioplasty of an internal mammary artery stenosis. This study examined a consecutive series of 68 patients who underwent balloon angioplasty of an internal mammary artery graft over a 9-year period. Procedural success was achieved in 60 of 68 (88%) patients. The primary reason for procedural failure was extreme vessel tortuosity. There were no major in-hospital complications. Angiographic follow-up was obtained in 78% of the patients with an angiographic restenosis rate of 19%. The overall event-free survival in patients with an initially successful procedure was 92%. In conclusion, internal mammary artery balloon angioplasty has both an excellent initial success rate as well as a low incidence of restenosis and repeat target lesion revascularization.

Myonecrosis after revascularization procedures

The detection of elevated cardiac enzyme levels and the occurrence of electrocardiographic (ECG) abnormalities after revascularization procedures have been the subject of recent controversy. This report represents an effort to achieve a consensus among a group of researchers with data on this subject. Creatine kinase (CK) or CK-MB isoenzyme (CK-MB) elevations occur in 5% to 30% of patients after a percutaneous intervention and commonly during coronary artery bypass graft surgery (CABG). Although Q wave formation is rare, other ECG changes are common. The rate of detection is highly dependent on the intensity of enzyme and ECG measurement. Because most events occur without the development of a Q wave, the ECG will not definitively diagnose them; even the ECG criteria for Q wave formation signifying an important clinical event have been variable. At least 10 studies evaluating > 10,000 patients undergoing percutaneous intervention have demonstrated that elevation of CK or CK-MB is associated not only with a higher mortality, but also with a higher risk of subsequent cardiac events and higher cost. Efforts to identify a specific cutoff value below which the prognosis is not impaired have not been successful. Rather, the risk of adverse outcomes increases with any elevation of CK or CK-MB and increases further in proportion to the level of intervention. This information complements similar previous data on CABG. Obtaining preprocedural and postprocedural ECGs and measurement of serial cardiac enzymes after revascularization are recommended. Patients with enzyme levels elevated more than threefold above the upper limit of normal or with ECG changes diagnostic for Q wave myocardial infarction (MI) should be treated as patients with an MI. Patients with more modest elevations should be observed carefully. Clinical trials should ensure systematic evaluation for myocardial necrosis, with attention paid to multivariable analysis of risk factors for poor long-term outcome, to determine the extent to which enzyme elevation is an independent risk factor after considering clinical history, coronary anatomy, left ventricular function and clinical evidence of ischemia. In addition, tracking of enzyme levels in clinical trials is needed to determine whether interventions that reduce periprocedural enzyme elevation also improve mortality.

Influence of coronary atherosclerotic remodeling on the mechanism of balloon angioplasty

OBJECTIVES

Intracoronary ultrasonography was used to assess coronary arteries before and after balloon percutaneous transluminal coronary angioplasty (PTCA) to determine whether the mode of coronary atherosclerotic remodeling affects the mechanism of balloon dilation.

BACKGROUND

Coronary arteries may enlarge or shrink in response to atherosclerotic plaque development. The effect of coronary remodeling on the mechanism of balloon PTCA has not yet been studied.

METHODS

Forty-one patients with 47 native de novo coronary artery lesions were studied with a 30 MHz intracoronary ultrasound catheter before and after balloon PTCA. Images were analyzed at the lesion site and the adjacent reference segments. At each site the lumen, vessel, and plaque area and the percent area stenosis were measured. Lesions were separated into two groups based on relative vessel area (lesion vessel area/reference vessel area). A relative vessel area >1.0 defines adaptive enlargement (group 1, n = 25), whereas a relative vessel area < or =1.0 reflects coronary shrinkage (group 2, n = 22). Regression analysis examined whether elastic recoil and the PTCA balloon/vessel area ratio correlated.

RESULTS

After balloon PTCA was performed, both the enlargement and shrinkage groups had similar gains in luminal area (2.3 +/- 1.8 mm2 [mean +/- SD] vs 2.8 +/- 1.7 mm2, p = 0.32), reduction in percent stenosis (-19.2% +/- 11.5% vs -14.4 +/- 12.7, p = 0.18), and final lumen area (4.9 +/- 1.7 mm2 vs 4.7 +/- 1.9 mm2, p = 0.73). However, the mechanism of luminal enlargement was different in each group. Reduction in plaque area was significantly greater in the enlargement group (group 1, -2.0 +/- 1.7 mm2 vs group 2, 0.04 +/- 2.2 mm2; p = 0.001), whereas increased vessel area was more important in the shrinkage group (group 1, 0.8 +/- 1.5 mm2 vs group 2, 2.4 +/- 2.3 mm2; p = 0.009). Positive correlation was seen between elastic recoil and the balloon/vessel area ratio in lesions with vessel enlargement (r = 0.80, p < 0.0001). No such correlation was observed in shrinkage vessels (r = 0.28, p = 0.21 ).

CONCLUSIONS

The acute luminal gain after balloon PTCA is similar regardless of the type of coronary remodeling. However, the mode of remodeling affects the mechanism of balloon dilation such that enlargement vessels exhibit plaque compression, whereas shrinkage arteries demonstrate vessel stretch. The post-PTCA elastic recoil correlates linearly to the balloon/vessel area ratio in arteries that have undergone adaptive enlargement.

Predictors of acute and long-term outcome with transluminal extraction atherectomy: the New Approaches to Coronary Intervention (NACI) registry

The New Approaches to Coronary Intervention (NACI) registry was established to define the role of new coronary devices in overcoming the limitations of balloon angioplasty. The purpose of the present study was to evaluate the acute and long-term efficacy of the transluminal extraction catheter (TEC) device utilizing data from the NACI registry and identify clinical and anatomic patient subsets who may benefit from this device. From 1990-1994, >4,300 patients from 39 clinical sites enrolled consecutive patients treated with one of the 7 new devices to the NACI registry. The study population consists of 331 patients (385 lesions) treated with planned TEC as the sole new device. Of these patients, 243 (292 lesions) were treated for saphenous vein graft (SVG) disease and 88 (93 lesions) for native disease. Patients undergoing SVG treatment were older and more likely to be male. They had lower ventricular function, more unstable angina, and a higher incidence of congestive heart failure. Multivessel disease was more prevalent in the SVG cohort, as was evidence of thrombus before treatment. Although device success was achieved in 50% of SVG lesions and 41% of native lesions, lesion success was achieved in 90% and 78%, respectively, after adjunctive balloon angioplasty, and procedure success rates were 86% and 79%, respectively. The in-hospital major complication (death/Q-wave myocardial infarction/emergency coronary artery bypass graft [CABG] surgery) rate was higher in the SVG cohort (6.2% vs 2.3%), mainly due to higher mortality rate (5.3% vs 1.1%). Multivariate analysis showed that SVG was not an independent predictor for either an in-hospital major complication or clinical failure. The risk factors for major in-hospital complications were history of congestive heart failure (odds ratio = 3.17) and thrombus (odds ratio = 3.36). For clinical failure the risk factors were diabetes (odds ratio = 1.88), thrombus (odds ratio = 2.08), and calcium (odds ratio = 3.09). One-year rates of death, Q-wave myocardial infarction, or any repeat revascularization were 51% in the SVG cohort and 41% in the native cohort. Following adjustment, patients treated for SVG disease did not have a higher risk when compared with those treated for native disease. The factors significantly associated with this composite event at 1 year are male (relative risk = 1.41), patients with history of congestive heart failure (relative risk = 1.56), and total occlusions (relative risk = 1.52). This study shows that for both SVG and native cohorts, device success rates were low with TEC alone, but acceptable lesion success rates were achieved when adjunctive PTCA was used. In-hospital as well as 1-year major complications were higher in the SVG cohort. However, after adjusting for other risk factors, SVG attempt was not significantly associated with either in-hospital or 1-year events.

A hypothesis regarding vascular acoustic emission accompanying arterial injury induced by balloon angioplasty

Stress-induced structural damage is often accompanied by sound release. This behavior is known as acoustic emission (AE). We hypothesize that vascular injury such as that produced by balloon angioplasty is associated with AE. Postmortem human peripheral arterial specimens were randomly partitioned into test (n = 10) and control segments (n = 10). Test segments were inserted into a pressurization circuit and subjected to two consecutive hydrostatic pressurizations. Amplitude, frequency, and energy content of the AE signals released during pressurization were quantified. Test and matched control segments subsequently underwent identical histological processing. Pressure-induced tissue trauma was estimated via computerized histomorphometric analysis of the resulting slides (n = 100). Vascular acoustic emission (VAE) signals exhibited an amplitude range of +/- 5.0 mu bars and were observed to occur during periods of increasing intraluminal pressure. The VAE signal power within the monitored bandwidth was concentrated below 350 Hz. More than 25 times as much VAE energy was released during the first pressurization as during the second: 1,855 +/- 513.8 mJ vs. 73 +/- 44.9 mJ (mean +/- SEM, p < 0.006). Estimates of circumferential intimal wall stress at AE onset averaged 170 kPa, slightly below reported values of arterial tissue rupture strength. Histomorphometric estimates of tissue trauma was greater for the test than their matched control segments (p < 0.0001). These preliminary data suggest that detectable acoustic energy is released by vascular tissue subjected to therapeutic stress levels. Histological analysis suggest that the underlying source of sound energy may be related to tissue trauma, independent of histological preparation artifacts. From this preliminary work, we conclude that VAE may be a fundamental property accompanying vascular tissue trauma, which may have applications to improving balloon angioplasty outcomes.

Rat tendon morphologic and functional changes resulting from soft tissue mobilization

Augmented Soft Tissue Mobilization (ASTM) is a new non-invasive soft tissue mobilization technique which has been used successfully to treat a variety of musculoskeletal disorders. The purpose of this study was to determine the effects of ASTM therapy on the morphological and functional characteristics of enzyme induced injured rat Achilles tendons. Four groups of five rats were allocated as follows: (A) control, (B) tendinitis, (C) tendinitis plus ASTM, and (D) ASTM alone. Collagenase injury was induced, and the surgical site was allowed to heal for 3 wk. ASTM was performed on the Achilles tendon of groups C and D for 3 min on postoperative days 21, 25, 29, and 33 for a total of four treatments. Gait data were gathered prior to each treatment. The Achilles tendons of each group were harvested 1 wk after the last treatment. Specimens were prepared for light and electron microscopy, and immunostaining for type I and type III collagen and fibronectin was performed. Light microscopy showed increased fibroblast proliferation in the tendinitis plus ASTM treatment group. Although healing in rats may not translate directly to healing in humans, the findings of this study suggest that ASTM may promote healing via increased fibroblast recruitment.

In vitro identification of angioplasty-induced injury by use of vascular acoustic emissions

BACKGROUND

We have developed a novel method of diagnosing stress-induced vascular injury. This approach uses the sound energy released from atherosclerotic arterial tissue during in vitro balloon angioplasty to characterize type and severity of induced trauma.

METHODS AND RESULTS

Thirty-two postmortem human peripheral arterial specimens 1.0 cm long were subjected to in vitro balloon angioplasty with simultaneous acoustic emission monitoring. Specimens were examined before and after angioplasty to ascertain the extent of angioplasty-induced injury. Gross observation was used to identify dissection. A three-dimensional intravascular ultrasound reconstruction technique was used to estimate the luminal surface area of the specimen. Change in luminal surface area (postangioplasty minus preangioplasty) was used to quantify induced injury. The energy content and spectral distribution of the digitally acquired vascular acoustic emission (VAE) signals were computed. Comparisons of angioplasty-induced trauma with VAE signal characteristics were made. Dissection (mural laceration of variable depth) was observed in 15 of 32 specimens. Eleven showed no evidence of induced dissection, and 6 had preexisting intimal disruptions. The energy content of the VAE signals collected from specimens with dissection was greater than that obtained from those in which dissection was absent: 845 +/- 89.4 mJ (mean +/- SEM; n = 15) versus 128 +/- 40.8 mJ (n = 1 l; P < .001). Comparison of induced trauma and VAE signal energy demonstrated a proportional relationship (r = .87, P < .001, n = 32).

CONCLUSIONS

VAE signals contain information characterizing type and severity of angioplasty-induced arterial injury. Because vascular injury is related to adverse procedural outcome, development of VAE technology as an adjunct to conventional diagnostic modalities may facilitate optimal balloon angioplasty delivery and postprocedural care.

Prognostic implication of creatine kinase elevation following elective coronary artery interventions

OBJECTIVE

To determine the prognostic significance of creatine kinase (CK) elevation following elective percutaneous transluminal coronary angioplasty (PTCA).

DESIGN

Retrospective cohort study.

SETTING

Tertiary care referral center.

SUBJECTS

A total of 253 consecutive patients with total CK and CK-MB fraction (CK-MB) elevation (case patients) and 120 patients without CK elevation (controls). Control patients had undergone interventions during the same month and year using the same devices.

MAIN OUTCOME MEASURES

In-hospital and late cardiac mortality, subsequent myocardial infarction, and the combined end point of cardiac mortality or myocardial infarction.

RESULTS

Patient groups were similar with respect to age, sex, extent of coronary artery disease, left ventricular function, number of lesions treated by PTCA, and mean duration of follow-up (>3.5 years). Cardiac mortality was significantly greater (P=.02) for patients with CK elevation after PTCA. When patients were categorized according to peak CK elevation, cardiac mortality differed significantly among patient groups (P=.007), with increased cardiac mortality observed for patients with high (>3.0 times normal) and intermediate (1.5 to 3.0 times normal) CK elevations. In multivariate analyses, higher peak CK and lower ejection fraction were the most important predictors of increased cardiac mortality (both, P<.001); the relative risk for cardiac mortality was 1.05 (95% confidence interval, 1.03-1.08) per 100-U/L increment increase in CK.

CONCLUSIONS

Creatine kinase elevation following elective PTCA is associated with increased late cardiac mortality. This increase in cardiac mortality is independent of clinical variables, severity of heart disease, coronary artery lesion characteristics, interventional devices, and procedural outcomes. Even patients with lesser degrees of CK elevation are at significantly increased risk for late cardiac death.

Intravascular ultrasound in the setting of directional coronary atherectomy and percutaneous transluminal coronary rotational atherectomy

The first section of this article reviews how intracoronary ultrasound (ICUS) has been used to identify the mechanisms of action of directional coronary atherectomy (DCA) and examines the influence of plaque composition and morphology on DCA outcomes. The process of restenosis is then described. Results from trial using ICUS-guided DCA are evaluated, demonstrating how the information obtained from ICUS is being used to improve the angiographic and clinical outcomes of directional atherectomy. Finally, data are incorporated to provide practical applications for the use of DCA.

Lesion-directed administration of alteplase with intracoronary heparin in patients with unstable angina and coronary thrombus undergoing angioplasty

Percutaneous coronary revascularization in patients with unstable angina and coronary thrombus carries a high complication rate. A new strategy to reduce thrombus burden before revascularization was tested in a multicenter prospective trial. Patients with unstable angina and coronary thrombus (n = 45) received alteplase through an infusion catheter at the proximal aspect of the target lesion and concomitant intracoronary heparin via a standard guiding catheter. Angiography was performed before and alter lesion-directed therapy and post-intervention. Systemic fibrinogen depletion and thrombin activation were not observed, while fibrinolysis was evident for > or = 4 hr after treatment. Target lesion stenosis did not change significantly after lesion-directed therapy, but thrombus score was reduced, particularly among patients who had large thrombi (mean 2.2 vs. 1.6, P = 0.02). Revascularization was successful in 89% of patients. Median final stenosis was 30% and mean final thrombus score was 0.4. Complications included recurrent ischemia (11%), MI (7%), abrupt closure (7%), severe bleeding (4%), and repeat emergency angioplasty (2%). Patients with overt thrombus appeared to derive the most angiographic benefit from lesion-directed alteplase plus intracoronary heparin. Later revascularization was highly successful. This strategy may be a useful adjunct to percutaneous revascularization for patients with unstable angina and frank intracoronary thrombus.

Accurate three-dimensional reconstruction of intravascular ultrasound data. Spatially correct three-dimensional reconstructions

BACKGROUND

The geometrical accuracy of conventional three-dimensional (3D) reconstruction methods for intravascular ultrasound (IVUS) data (coronary and peripheral) is hampered by the inability to register spatial image orientation and by respiratory and cardiac motion. The objective of this work was the development of improved IVUS reconstruction techniques.

METHODS AND RESULTS

We developed a 3D position registration method that identifies the spatial coordinates of an in situ IVUS catheter by use of simultaneous ECG-gated biplane digital cinefluoroscopy. To minimize distortion, coordinates underwent pincushion correction and were referenced to a standardized calibration cube. Gated IVUS data were acquired digitally, and the spatial locations of the imaging planes were then transformed relative to their respective 3D coordinates, rendered in binary voxel format, resliced, and displayed on an image-processing workstation for off-line analysis. The method was tested by use of phantoms (straight tube, 360 degrees circle, 240 degrees spiral) and an in vitro coronary artery model. In vivo feasibility was assessed in patients who underwent routine interventional coronary procedures accompanied by IVUS evaluation. Actual versus calculated point locations were within 1.0 +/- 0.3 mm of each other (n = 39). Calculated phantom volumes were within 4% of actual volumes. Phantom 3D reconstruction appropriately demonstrated complex morphology. Initial patient evaluation demonstrated method feasibility as well as errors if respiratory and ECG gating were not used.

CONCLUSIONS

These preliminary data support the use of this new method of 3D reconstruction of vascular structures with use of combined vascular ultrasound data and simultaneous ECG-gated biplane cinefluoroscopy.

Balloon aortic valvuloplasty in adults: failure of procedure to improve long-term survival

OBJECTIVES

This study sought to determine the long-term outcome of adult patients undergoing percutaneous balloon aortic valvuloplasty.

BACKGROUND

Percutaneous balloon aortic valvuloplasty has been offered as an alternative to aortic valve replacement for selected patients with valvular aortic stenosis. Although balloon aortic valvuloplasty produces an immediate reduction in the transvalvular aortic gradient, a high incidence of restenosis frequently leads to recurrent symptoms. Therefore, it is unclear whether balloon aortic valvuloplasty impacts on the long-term outcome of these patients.

METHODS

Clinical, hemodynamic and echocardiographic data were collected at baseline in 165 patients undergoing balloon aortic valvuloplasty and examined for their ability to predict long-term outcome.

RESULTS

The median duration follow-up was 3.9 years (range 1 to 6). Ninety-nine percent follow-up was achieved. During this 6-year period, 152 patients (93%) died or underwent aortic valve replacement, and 99 (60%) died of cardiac-related causes. The probability of event-free survival (freedom from death, aortic valve replacement or repeat balloon aortic valvuloplasty) 1, 2 and 3 years after valvuloplasty was 40%, 19% and 6%, respectively. In contrast, the probability of survival 3 years after balloon aortic valvuloplasty in a subset of 42 patients who underwent subsequent aortic valve replacement was 84%. Survival after aortic valvuloplasty was poor regardless of the presenting symptom, but patients with New York Heart Association functional class IV congestive heart failure had events earliest. Univariable predictors of decreased event-free survival were younger age, advanced congestive heart failure symptoms, lower ejection fraction, elevated left ventricular end-diastolic pressure, presence of coronary artery disease and increased left ventricular internal diastolic diameter. Stepwise multivariable logistic regression analysis found that only younger age and a lower left ventricular ejection fraction contributed independent adverse prognostic information (chi-square 14.89, p = 0.0006).

CONCLUSIONS

Long-term event-free and actuarial survival after balloon aortic valvuloplasty is dismal and resembles the natural history of untreated aortic stenosis. Aortic valve replacement may be performed in selected subjects with good results. However, the prognosis for the remainder of patients who are not candidates for aortic valve replacement is particularly poor.

Aortic valve replacement in adults after balloon aortic valvuloplasty

BACKGROUND

Percutaneous balloon aortic valvuloplasty is limited by a high risk of procedural morbidity, transient clinical benefit, and a high restenosis rate. The management of patients with symptomatic aortic valve restenosis after percutaneous balloon aortic valvuloplasty is unclear. We hypothesized that aortic valve replacement would produce superior midterm survival compared with repeat balloon aortic valvuloplasty or medication alone in patients with symptomatic aortic valve restenosis after prior balloon aortic valvuloplasty.

METHODS AND RESULTS

Baseline clinical, echocardiographic, and hemodynamic data were collected on 165 patients who underwent percutaneous balloon aortic valvuloplasty as treatment for symptomatic degenerative calcific aortic stenosis. In 144 of these patients (87%), aortic valve replacement was originally considered to carry excessive risk. The survival of three subgroups was calculated during a median follow-up period of 3.9 years (range, 1 to 6 years). Ninety-four patients (57%) had no further mechanical intervention (subgroup 1-BAV), 31 patients (19%) developed symptomatic aortic valve restenosis and underwent a repeat balloon aortic valvuloplasty (subgroup 2-BAV), and 40 patients (24%) subsequently underwent aortic valve replacement (subgroup BAV+AVR). Follow-up was 99% complete. Patients in subgroup BAV+AVR tended to be younger and have a lower prevalence of coronary artery disease or mitral regurgitation. Only 1 patient (2.5%) suffered a perioperative death during aortic valve replacement. The probability of survival 3 years from the date of the last mechanical intervention was 13% for subgroup 1-BAV, 20% for subgroup 2-BAV, and 75% for subgroup BAV+AVR. At the conclusion of follow-up, only 2 patients had symptoms of congestive heart failure or angina after aortic valve replacement.

CONCLUSIONS

Aortic valve replacement may be performed with a low mortality rate, excellent palliation of symptoms, and prolongation of survival in selected high-risk patients with a history of previous balloon aortic valvuloplasty.

Rapid visualization of massive pulmonary emboli utilizing intravascular ultrasound

Massive pulmonary embolism may result in rapid deterioration prior to diagnostic and therapeutic intervention. Intravascular ultrasound imaging has been utilized previously to evaluate vascular abnormalities as well as normal human pulmonary arteries. We employed this technique to rapidly identify massive pulmonary emboli located in the main pulmonary arteries of two patients. The presence of these emboli was confirmed with pulmonary arteriography. Intravascular ultrasound may be utilized to rapidly confirm the presence of large proximal pulmonary emboli.

Vocational rehabilitation services in workers' compensation programs: evaluating research model effectiveness

Vocational rehabilitation programs are a strategy used by many, employers to manage workers' compensation costs and the consequence of injuries for their workers. Soaring costs for employers and public entities associated with workers' compensation programs and vocational rehabilitation services indicate that additional research is needed--a need further demonstrated by the serious financial, social and psychological costs that workplace disability exacts from workers.

Ultrasound guide wire-directed stent deployment

A new mechanically rotated 20 MHz intravascular ultrasound guide wire (0.032 inch) with a transducer core was placed through the central lumen of a peripheral arterial balloon-expandable stent. Using an anesthetized canine model, 11 stents were then deployed into the iliac or femoral arteries. Eight stents were successfully deployed with proper position and full stent expansion documented by ultrasound imaging. Four of the stents were overlapping and the double row of stent struts at the region of overlap was easily seen. Three stents were unsuccessfully deployed because of undersizing, as clearly documented by ultrasound imaging showing stent strut recoil. As a result, the procedure was modified by performing ultrasound measurements of arterial dimensions before stent selection. There were no complications attributed to the ultrasound guide wire. This study demonstrates an effective combination of diagnostic and therapeutic devices that may allow more precise placement of intravascular stents.

In vivo validation of compensatory enlargement of atherosclerotic coronary arteries

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 myocardial 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 +/- 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 mm2). 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 < 30% area stenosis were examined, internal elastic lamina correlated well with plaque area (r = 0.79, and p = 0.0001), and for each 1 mm2 increase in plaque area, internal elastic lamina increased 2.7 mm2. This suggests that arterial enlargement may overcompensate for early atherosclerotic lesions.(ABSTRACT TRUNCATED AT 250 WORDS)