Lp-PLA₂- a novel risk factor for high-risk coronary and carotid artery disease

Lipoprotein-associated phospholipase A2 (Lp-PLA₂) is at the crossroads of lipid metabolism and the inflammatory response. It is produced by inflammatory cells, bound to LDL and other lipoproteins, and once in the arterial wall facilitates hydrolysis of phospholipids. Elevated serum levels of Lp-PLA₂ have been associated with increased cardiovascular risk in healthy populations and in patients with known vascular disease. Here, we review the role of Lp-PLA₂ in the development of atherosclerosis and progression to unstable disease, the utility of Lp-PLA₂ as a risk predictor for coronary and carotid events and the potential clinical benefit of pharmacologic inhibition of Lp-PLA₂.

First-In-Man application of a miniature self-contained intracoronary magnetic resonance probe. A multi-centre safety and feasibility trial

AIMS

To assess safety and feasibility of intracoronary Magnetic Resonance (MR) Spectroscopy in living patients, using a self-contained MR catheter.

METHODS AND RESULTS

Prospective, multi-centre study in patients with stable or unstable angina that were scheduled for percutaneous coronary diagnostic or therapeutic catheterization. We assessed the feasibility of an intravascular MR catheter, capable of analysing the arterial wall without external magnets or coils, by differentiating lipid rich, intermediate and fibrotic areas of the atherosclerotic plaque on the basis of differential water diffusion.Twenty-nine patients were included at 4 centres. The intracoronary MR-spectroscopy procedure was well tolerated; no MACE and no device related serious adverse event was observed. The MR catheter was successfully advanced into the lesion in 28 patients. Introduction of the MR catheter was not possible in one patient with a tortuous proximal right coronary artery. MR data were obtained in 22 patients. According to the predominant MR pattern, lesions were classified as fibrous plaque in 4 patients, as intermediate plaque in 4 patients and as lipid-rich plaque in 8 patients. Six patients were excluded from analysis because artifacts impeded the quality of the MR signal. Plaque type did not show a correlation with angina status (p=0.552; all groups) or angiographic parameters, such as minimal lumen diameter and diameter stenosis.

CONCLUSIONS

This prospective, multi-centre study demonstrates for the first time that coronary artery assessment of potentially vulnerable, non-flow limiting lesions using a dedicated intravascular MR catheter, free of external magnets or coils, is feasible in clinical practice. Assessment of the coronary wall may provide important data regarding the composition of the atherosclerotic lesion, which then could contribute to predicting the likelihood of eventual rupture and clinical instability.

Local delivery of a hydrophobic heparin reduces neointimal hyperplasia after balloon injury in rat carotid but not pig coronary arteries

BACKGROUND

Intimal hyperplasia following percutaneous interventional vascular procedures is a major cause of restenosis. Although heparin inhibits intimal hyperplasia, it has not proven clinically useful in part due to an inadequate duration of intramural drug residence. This study was designed to evaluate the efficacy of local delivery of hydrophobic heparin (PTIR-RS-1), exhibiting increased intramural binding, on neointimal hyperplasia after angioplasty injury.

METHODS AND RESULTS

PTIR-RS-1 was delivered locally into rat carotid arteries at three doses: 0.1 mM (440 IU), 0.3 mM (1320 IU), or 1.0 mM (4400 IU). Animals were killed at 14 days. In the pig, the doses tested were the low dose in the rat and a high dose 1 log higher. Animals were killed 28 days later. Morphometric analysis was performed to evaluate the intima: media ratio in rats and the normalized neointimal area in pigs. In rats a significant reduction in neointimal to medial area ratio from 0.73 +/- 0.15 for control vs 0.80 +/- 0.27 for sodium heparin (P = NS) and 0.15 +/- 0.07 for the 0.1 mM PTIR-RS-1 dose (P < 0.008). In pigs, PTIR-RS-1 the high dose reduced the normalized neointimal area by 16%, a difference that was not statistically significant.

CONCLUSIONS

Increased hydrophobicity of heparin reduced neointimal area following balloon overstretch injury in the rat carotid but not the pig coronary artery model. This study attests to the importance of performing studies evaluating the pharmacologic effect of local delivery of a medication in at least two animal models of restenosis.

Extent and distribution of in-stent intimal hyperplasia and edge effect in a non-radiation stent population

Intimal hyperplasia within the body of the stent is the primary mechanism for in-stent restenosis; however, stent edge restenosis has been described after brachytherapy. Our current understanding about the magnitude of in vivo intimal hyperplasia and edge restenosis is limited to data obtained primarily from select, symptomatic patients requiring repeat angiography. The purpose of this study was to determine the extent and distribution of intimal hyperplasia both within the stent and along the stent edge in relatively nonselect, asymptomatic patients scheduled for 6-month intravascular ultrasound (IVUS) as part of a multicenter trial: Heparin Infusion Prior to Stenting. Planar IVUS measurements 1 mm apart were obtained throughout the stent and over a length of 10 mm proximal and distal to the stent at index and follow-up. Of the 179 patients enrolled, 140 returned for repeat angiography and IVUS at 6.4 +/- 1.9 months and had IVUS images adequate for analysis. Patients had 1.2 +/- 0.6 Palmaz-Schatz stents per vessel. There was a wide individual variation of intimal hyperplasia distribution within the stent and no mean predilection for any location. At 6 months, intimal hyperplasia occupied 29.3 +/- 16.2% of the stent volume on average. Lumen loss within 2 mm of the stent edge was due primarily to intimal proliferation. Beyond 2 mm, negative remodeling contributed more to lumen loss. Gender, age, vessel location, index plaque burden, hypercholesterolemia, diabetes, and tobacco did not predict luminal narrowing at the stent edges, but diabetes, unstable angina at presentation, and lesion length were predictive of in-stent intimal hyperplasia. In a non-radiation stent population, 29% of the stent volume is filled with intimal hyperplasia at 6 months. Lumen loss at the stent edge is due primarily to intimal proliferation.

Gene delivery from a DNA controlled-release stent in porcine coronary arteries

Expandable intra-arterial stents are widely used for treating coronary disease. We hypothesized that local gene delivery could be achieved with the controlled release of DNA from a polymer coating on an expandable stent. Our paper reports the first successful transfection in vivo using a DNA controlled-release stent. Green fluorescent protein (GFP) plasmid DNA within emulsion-coated stents was efficiently expressed in cell cultures (7.9% +/- 0.7% vs. 0.6% +/- 0.2% control, p < 0.001) of rat aortic smooth muscle cells. In a series of pig stent-angioplasty studies, GFP expression was observed in all coronary arteries (normal, nondiseased) in the DNA-treated group, but not in control arteries. GFP plasmid DNA in the arterial wall was confirmed by PCR, and GFP presence in the pig coronaries was confirmed by immunohistochemistry. Thus, DNA-eluting stents are capable of arterial transfection, and could be useful as delivery systems for candidate vectors for gene therapy of cardiovascular diseases.

Prospective study correlating fibrinopeptide A, troponin I, myoglobin, and myosin light chain levels with early and late ischemic events in consecutive patients presenting to the emergency department with chest pain

BACKGROUND

Although thrombus formation plays a major role in acute coronary syndromes, few studies have evaluated a thrombus marker in risk stratification of patients with chest pain. Furthermore, the relation between markers that reflect myocardial injury and thrombus formation that may predict events in a heterogeneous patient population is unknown. This study correlated markers of thrombus and myocardial injury with early and late ischemic events in consecutive patients with chest pain.

METHODS AND RESULTS

Serum troponin I (TnI), myoglobin, and myosin light chain levels were obtained from 247 patients and urinary fibrinopeptide A (FPA) from 178 of the 247. By multivariate analysis, patients with an elevated FPA level were 4.82 times more likely to die or have myocardial infarction, unstable angina, and coronary revascularization at 1 week (P=0.002, 95% CI 1.78, 13.03), whereas those with an elevated TnI (>0.2 ng/mL) were 9.41 times more likely (P<0.001, 95% CI 2.84, 31.17). At 6 months (excluding the index event), an elevated FPA level was an independent predictor of events, with an odds ratio of 9.57 (P<0.001, C1 3.29, 27.8), and was the only marker to predict a shorter event-free survival (P<0.001). The other markers did not independently correlate with cardiac events, although MLC incrementally increased early predictive accuracy in combination with the FPA and TnI.

CONCLUSIONS

Elevated FPA and TnI correlated with cardiac events during the initial week in patients presenting to the Emergency Department with chest pain. FPA predicted adverse events and a shorter event-free survival at 6 months.

Combination therapy with clopidogrel and aspirin after coronary stenting

Combination antiplatelet therapy using aspirin and ticlopidine has been the standard of care for prevention of subacute thrombosis following coronary stent implantation. However, the use of ticlopidine is associated with a significant risk of adverse hematologic side effects. Clopidogrel is an inhibitor of ADP-induced platelet aggregation that has a better safety profile than ticlopidine. We examined the 30-day clinical outcome following coronary stent implantation in 253 consecutive patients treated with clopidogrel and aspirin. Follow-up was achieved in 99% of patients and four adverse events were documented. Two patients had angiographically confirmed subacute stent thrombosis (0.8%), and both of these patients underwent successful repeat angioplasty at the stent site. There were two patient deaths during follow-up (0. 8%). One was sudden within 1 week of stent placement and the other occurred in a patient with multisystem organ failure after an extensive myocardial infarction that antedated the stent procedure, with no clinical evidence for stent thrombosis. The combined frequency of subacute stent thrombosis and death was 1.6%. This is comparable to prior studies using the combination of ticlopidine and aspirin following stenting. Therefore, clopidogrel in combination with aspirin appears to be a safe and effective therapy in the prevention of subacute thrombosis following coronary stent implantation.

Predictors of clinical outcome following percutaneous intervention for in-stent restenosis

Percutaneous intervention for the first episode of in-stent restenosis was performed in 177 patients 5.4 +/- 0.3 months after native coronary stent implantation. Medical records were reviewed and patients contacted 13.3 +/- 1.2 months after in-stent intervention to ascertain the subsequent clinical course. The effects of demographic, procedural, and angiographic variables on clinical outcomes were determined. At 2 years, Kaplan-Meier estimated survival was 93 +/- 3% and freedom from death, myocardial infarction, and a third target artery revascularization (TAR) was 67 +/- 4%. The actuarial frequency of a third TAR was 26 +/- 4% at 1 year. Stratification of outcomes according to timing of in-stent intervention revealed an approximate twofold higher frequency of adverse events among patients with early (</=3 months) in-stent restenosis. Advanced age (p = 0.019), prior coronary bypass (p = 0. 017), and early in-stent intervention (p = 0.006) independently predicted increased mortality at follow-up. Systemic hypertension (p = 0.004), diabetes mellitus (p = 0.044), and early in-stent intervention (p <0.0001) independently predicted a third TAR. These variables (p = 0.007, p = 0.027, and p <0.0001, respectively) also independently predicted a composite end point consisting of death, myocardial infarction, and a third TAR. No angiographic variable predicted outcome after in-stent intervention. Thus, long-term outcome following in-stent intervention was favorable. Early in-stent intervention, advanced age, hypertension, and diabetes predicted adverse outcomes.

Heparin infusion prior to stenting (HIPS) trial: final results of a prospective, randomized, controlled trial evaluating the effects of local vascular delivery on intimal hyperplasia

BACKGROUND

Local delivery of pharmacologic agents or genes at the site of angioplasty is a promising approach to reduce restenosis. However, there are unresolved questions concerning the safety and feasibility of local vascular delivery in clinical practice as well as the efficacy of delivered drug. To this end, the safety, feasibility, and efficacy of local delivery of heparin were evaluated in the Heparin Infusion Prior to Stenting (HIPS) trial.

METHODS AND RESULTS

A total of 179 patients were enrolled in this multicenter, randomized, prospective, core laboratory-evaluated trial. Patients were randomly assigned to 5000 U heparin either administered to the coronary artery lumen or infused into the arterial wall immediately after angioplasty and before stent placement. End points included procedural events and clinical, angiographic, and intravascular ultrasound events at 6 months. Patient groups were evenly matched. There was no difference in the incidence of arterial injury, defined as an increase in arterial dissection, acute closure, or decrease in Thrombolysis In Myocardial Infarction grade blood flow in the group receiving local delivery. At follow-up there was no difference in the major adverse event rate between intraluminal (22.7%) and local groups (24.7%). There was no difference between intraluminal and local therapy in the angiographic in-stent restenosis rate (12.5%, 12.7%) or the in-stent volumetric analysis by intravascular ultrasound (IVUS) (37.19 +/- 20. 86 mm(3) vs 43.79 +/- 25.52 mm(3)).

CONCLUSIONS

Local delivery of 5000 U heparin into the arterial wall before stent implantation is safe and feasible. There was not a favorable effect of locally delivered heparin on clinical, angiographic, or IVUS end points of restenosis. The use of IVUS to measure volume of intimal hyperplasia in a multicenter, core laboratory-controlled trial is feasible.

Vascular remodeling and the local delivery of cytochalasin B after coronary angioplasty in humans

OBJECTIVES

This study sought to determine the safety, feasibility and outcome of local delivery of cytochalasin B at the site of coronary angioplasty.

BACKGROUND

Previous failures in the pharmacologic prevention of restenosis may have been related to inadequate dosing at the angioplasty site as a result of systemic drug administration. Alternatively, although previous experimental protocols have typically targeted control of excess tissue growth (intimal hyperplasia), it now appears that overall arterial constriction (vascular remodeling) is the major contributor to late lumen loss. Cytochalasin B inhibits the polymerization of actin and has proved to be a potent inhibitor of vascular remodeling in animal models.

METHODS

In this phase I, multicenter, randomized, controlled trial, cytochalasin B (or matching placebo) was administered to the site of a successful balloon angioplasty using a microporous local delivery infusion balloon.

RESULTS

The rate of drug delivery at a constant infusion pressure varied significantly from patient to patient (range 1.7 to 20.2 ml/min), perhaps related to a variable constricting effect of the atherosclerotic plaque on the infusion balloon. The minimal stenosis diameter after the procedure was slightly better in the active drug group (1.86 +/- 0.44 vs. 1.49 +/- 0.63 mm, p < 0.03), but this difference was not seen at four to six weeks. Although the study was not powered for clinical outcomes (n = 43), the combined end point (death, nonfatal infarction or repeat revascularization) was encountered in 20% of the patients receiving cytochalasin B and in 38% of the patients receiving placebo. Clinical restenosis occurred in 18% of the treatment group and 22% of the placebo group. There were no significant differences between groups in biochemical or electrocardiographic variables.

CONCLUSIONS

Cytochalasin B can be safely administered by local delivery after successful coronary angioplasty and warrants further study of its efficacy in reducing restenosis.

Increased thrombin activity correlates with increased ischemic event rate after percutaneous transluminal coronary angioplasty: lack of efficacy of locally delivered urokinase

BACKGROUND

Angiographic thrombus is associated with increased coronary occlusion and restenosis rates after angioplasty. Administration of intracoronary urokinase decreases the incidence of thrombus but is associated with an increased periprocedural event rate, including stroke and myocardial infarction. An alternative approach is to deliver the agent directly into the arterial wall, thereby reducing the thrombotic substrate in the absence of a systemic effect of the delivered agent.

OBJECTIVE

This randomized, double-blind, prospective study correlated intracardiac fibrinopeptide A levels with the ischemic events after angioplasty and evaluated whether locally administered urokinase could reduce the event rate.

METHODS

Fifty-four patients with acute coronary syndromes were randomly assigned to local delivery of urokinase or saline. Levels of fibrinopeptide A, a marker of thrombin activity, were obtained before and after administration of heparin, after 2 balloon inflations, and at the end of the procedure in 43 patients and were correlated with ischemic events within the 6-month follow-up period (death, myocardial infarction, or recurrent ischemia).

RESULTS

Multivariant analysis revealed that an elevated fibrinopeptide A level before angioplasty significantly correlated with an increased likelihood of an adverse event over the 6-month clinical follow-up. A postangioplasty reduction in the fibrinopeptide A level was noted in control patients (P <.001), but not after local urokinase administration, and the final fibrinopeptide A level was higher in the urokinase group (P =.02). Urokinase had no effect on the procedural results. On follow-up more patients receiving urokinase (13 of 27) had ischemic events than did control patients (6 of 25, P =.04). Most events were recurrent ischemia caused by restenosis.

CONCLUSIONS

Heparin-resistant thrombin activity, as evidenced by an increased fibrinopeptide A level correlates with ischemic events on long-term follow-up. Local delivery of urokinase increased the event rate.

Sustained Intramural Retention and Regional Redistribution Following Local Vascular Delivery of Polylactic-Coglycolic Acid and Liposomal Nanoparticulate Formulations Containing Probucol

BACKGROUND: Probucol reduces restenosis after angioplasty, provided oral administration is begun 1 month before the procedure. Local vascular delivery of a nonoparticulate formulation of probucol may obviate the need for drug loading by acutely raising arterial intramural concentration while providing sustained intramural retention. To test this hypothesis, we compared the retention and redistribution of (35)S-probucol encapsulated in either liposomal or polylactic-coglycolic acid (PLGA) nanoparticles after local vascular delivery. METHODS: Nanoparticles were delivered using a Crescendo microporous infusion catheter (Cordis, Warren, NJ) after balloon angioplasty of rabbit iliac arteries (n = 12-18 arteries per formulation per time point). Animals were euthanized on day 0, 3, or 7 after delivery. Iliac arteries, perivascular fat, and downstream tissues were harvested and the radioactivity disintegrations per minute was measured. Autoradiographic and confocal microscopic analyses of tissue sections were performed to evaluate intramural distribution of probucol. RESULTS: Immediately after delivery, radioactivity in the iliac arteries (log[dpm/mg], mean +/- SEM) was greater with PLGA (2.72 +/- 0.08) than with liposomal encapsulation (2.10 +/- 0.08, P = 0.001). Intramural retention of probucol was 23% at 7 days using liposomes and 10% using PLGA, corresponding to a probucol concentration of 0.1 ng/mg tissue for both formulations. By the third day after delivery, radioactivity in peri-iliac fat, femoral arteries, and hindlimb muscle increased by 88%, 29%, and 154%, respectively. Thereafter, radioactivity decreased to 56%, 43%, and 134% of initial dpm respectively, by day 7. CONCLUSIONS: although delivery efficiency was superior with PLGA encapsulation, intramural probucol concentrations were similar on day 7 using both formulations. Radial and axial redistribution of probucol was observed, indicating that this technique can be exploited to increase adjacent tissue delivery.

Case study: analysis of an acute anterior-lateral myocardial infarction in a 16-year-old patient with familial hypercholesterolemia

This article presents a case study of a 16-year-old male patient with a significant family history for hypercholesterolemia and coronary artery disease, who suffered an anterior lateral myocardial infarction. On admission, his electrocardiograms revealed the classic pattern of an anterior lateral acute myocardial infarction plus a left anterior hemiblock. His cholesterol level was 750 mg/dL, and his low-density lipoprotein was 650 mg/dL. He underwent a cardiac catheterization that revealed an occluded left anterior descending artery requiring a percutaneous transluminal angioplasty and three coronary stents. The 12-lead electrocardiograms on admission and before discharge are analyzed. This article discusses the electrocardiogram characteristics of anterior lateral wall myocardial infarction coupled with a left anterior hemiblock.

Increased Intramural Retention After Local Delivery of Molecules with Increased Binding Properties: Implications for Regional Delivery of Pharmacologic Agents

BACKGROUND: Catheter-based local vascular delivery results in concentrated qualtities of pharmaceutical agents or genes into focal areas of the arterial wall. However, intramural retention is short and has reduced the potential efficacy of this approach. It was postulated that agents that possess increased intramural binding would show increased intramural retention. Platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF) were models of agents with increased cellular and extracellular matrix binding properties. METHODS AND RESULTS: The delivery efficiency and intramural retention of 2 mL of saline containing I(125) labeled PDGF (n = 35 arteries) and bFGF (n = 24) were compared with albumin (n = 21) after local delivery into porcine coronary arteries. Animals were sacrificed at three or more prespecified timepoints: immediately after delivery, 1 day, or 3 days after delivery and if necessary at 5 or 7 days to document prolonged retention. Autoradiograms of the arterial sections were evaluated for the extent of delivery. Delivery efficiency, defined as the amount leaving the catheter and retrieved from the arterial wall, was 0.60% +/- 0.42% for albumin, 1.98% +/- 0.88% for PDGF (P =.001), and 0.31% +/- 0.11% for bFGF. The calculated intramural half-life of albumin was 7.4 hours, 56.2 hours for PDGF, and 14.9 hours for bFGF (P =.0001 for PDGF). Infusate covering >50% of the medial area was observed in 85% of arteries immediately after delivery. Although myocardial delivery was similar for albumin, PDGF, and bFGF, myocardial retention was significantlylonger for bFGF (P <.001). CONCLUSIONS: Molecules that exhibit preferential intramural binding show a longer intramural residence duration than solutes without such binding properties. In addition, delivery and subsequent prolonged retention in the myocardium can be obtained by local delivery via the arterial lumen of solutions with preferential binding properties.

Clinical utility of troponin T levels and echocardiography in the emergency department

We investigated the clinical utility of cardiac troponin T (TnT) and echocardiography in the emergency department to predict subsequent in-hospital diagnosis and adverse cardiac events. TnT is a cardiac-specific protein released during cell injury such as that following acute myocardial inFarction (MI). Unlike creatine kinase-MB isoenzymes, TnT is increased in a subset of patients with unstable angina, and these may be at higher risk for subsequent cardiac events. Echocardiography is a useful noninvasive imaging technique for the assessment of ischemic heart disease in acute care settings because of its mobility and rapid results. Serial TnT determinations and echocardiographic images were prospectively evaluated in 100 patients with chest discomfort and admitted to the hospital. Serum was obtained for CKMB and TnT on presentation to the emergency department and 4, 8, 16 and 24 hours later. TnT was considered increased when at values greater than 0.1 microg/L. Echocardiograms were recorded on videotape in the emergency department and images reviewed in a blinded fashion for wall-motion abnormalities. When available, current echocardiographic results were compared with previous results to determine whether a new wall-motion abnormality was present. Of the 100 patients (57 men, 43 women), TnT was increased in 21 of 21 with acute MI and 15 of 41 with unstable angina. One of the 38 patients with stable angina had an increased TnT value and died 5 months later of a noncardiac cause. Ninety percent of patients who sustained acute MI had a TnT increase detected within 4 hours of presentation. Fifteen of 18 patients with acute MI and 9 of 37 patients with unstable angina had a new wall-motion abnormality on echocardiography. The combination of TnT levels with echocardiography yielded a positive predictive value of 84% and a negative predictive value of 90% for adverse cardiac events in the follow-up population, which was more accurate than either test analyzed separately. TnT and echocardiography are useful tests in emergency department triage of unstable coronary syndromes. Both tests are predictive of discharge diagnosis and follow-up events. However, the combined utility of TnT levels and echocardiographic imaging is a more powerful predictor of adverse cardiac events than isolated results.

Activation of MAP kinase in vivo follows balloon overstretch injury of porcine coronary and carotid arteries

Vascular restenosis involves contraction, proliferation, and remodeling of the arterial wall in response to overstretch injury. Mitogen-activated protein kinases (MAPKs) are implicated in both contraction and proliferation of vascular smooth muscle (VSM), and studies of porcine carotid arterial muscle strips have shown that mechanical stretch leads to the activation of the extracellular signal-regulated kinase (ERK) family of MAPKs in vivo. We, therefore, analyzed the acute effect of mechanical overstretch injury on ERK-MAPK (herein referred to simply as MAPK) activity in porcine coronary and carotid arteries in vivo. Balloon angioplasty catheters were inflated to 6 atm three times over 5 minutes at a balloon-artery ratio of 1.2:1 in either porcine coronary or carotid arteries. The arteries were snap-frozen after angioplasty, and MAPK activity was measured. Angioplasty of the left anterior descending (LAD, n = 5), left circumflex (LCx, n = 5), and carotid (n = 5) arteries effected an increase in MAPK activity compared with the activity in uninstrumented right coronary arteries (RCAs) or carotid arteries from the same animals used for controls. Balloon angioplasty of carotid arteries led to an increase in MAPK activity that was 7.7-fold over the activity in control arteries and comparable to the activity in stretched carotid arterial muscle strips in vivo. The increase in coronary artery kinase activity on angioplasty was variable from animal to animal. The increase in MAPK activity over that in control arteries ranged from 4.5- to 31.7-fold (mean +/- SEM, 10.7 +/- 5.3) in the LAD and 1.8- to 31.3-fold (mean +/- SEM, 9.7 +/- 5.7) in the LCx. There were no apparent inherent differences in the levels of MAPK activity in the three different types of coronary arteries (RCA, LAD, and LCx) without instrumentation. MAPK activation occurs rapidly during angioplasty, suggesting that this kinase may play an early role in initiating the injury response in both porcine coronary and carotid arteries. MAPKs may be key enzymes targeted to treat or prevent restenosis.

Measurement of coronary artery calcium with dual-slice helical CT compared with coronary angiography: evaluation of CT scoring methods, interobserver variations, and reproducibility

OBJECTIVE

This study was performed to evaluate new scoring methods for quantitating coronary artery calcifications with helical CT and to compare the results with those of quantitative coronary angiography in patients with suspected coronary artery disease.

SUBJECTS AND METHODS

Unenhanced dual-slice helical CT and coronary angiography were performed within 24 hr of each other in 101 patients with symptoms of coronary artery disease. Coronary artery calcifications with a density above 90 H were identified on each slice and, with the same regions of interest, quantitative scoring was performed at thresholds of 90 H (new) 130 H (old). Two mathematical algorithms (one new and one old) were evaluated for both thresholds (yielding four scoring systems). By CT imaging, we defined disease as a score of greater than zero. By angiography, we defined disease as a 50% or greater reduction in the luminal diameter of any major vessel. Interobserver variations in calcification scoring were evaluated. Seventeen of our patients. also underwent a second, consecutive CT scan to determine reproducibility.

RESULTS

With the new threshold and the new algorithm, the sensitivity, specificity, and accuracy of helical CT in predicting disease were 88%, 52%, and 76%, respectively. We found a moderate positive association between the total CT calcification score and the number of stenotic coronary arteries at angiography (Pearson's correlation coefficient, .43; p = .05 [analysis of variance]). The accuracy and the area under the receiver operating characteristic curve were higher with the new threshold and the new algorithm. Interobserver agreement in calcification scoring was high (intraclass correlation coefficient, .99 [n = 85]), as was reproducibility (intraclass correlation coefficient, .94 [n = 17]). Reproducibility was higher when scoring was based on the new threshold and the new algorithm.

CONCLUSION

The quantity of coronary artery calcifications as measured by helical CT correlated positively with obstructive coronary artery disease as measured by angiography. Interobserver agreement and reproducibility were excellent. A new scoring method showed promise.

Vascular repair mechanisms after directional atherectomy or percutaneous transluminal coronary angioplasty in atherosclerotic rabbit iliac arteries

Although directional atherectomy (DA) reduces the plaque burden, successful revascularization is not associated with a reduced restenosis rate when compared with percutaneous transluminal coronary angioplasty (PTCA). The purpose of this study was to compare and contrast the vascular response to DA-induced and PTCA-induced injury. Six to 8 weeks after induction of atherosclerosis, PTCA (n = 34) was performed in one iliac artery and DA in the other (n = 30). Arteries were obtained at 6 time points: 1, 3, 5, 7, 14, and 28 days. Eleven arteries that did not undergo an intervention acted as controls. Radiograms obtained before and after intervention and at euthanization were compared. Morphometric, histologic, and immunohistochemical analyses were performed. Both PTCA and DA resulted in an immediate increase in luminal diameter that subsequently decreased over the ensuing month. PTCA caused deep dissection (7 of 8 arteries), often extending to the adventitia, whereas stand alone DA resulted in deep cleft formation (4 of 5). Of the 30 arteries that underwent DA, 4 exhibited an increase in luminal diameter in the absence of tissue retrieval. Thrombus was observed in both the dissection planes and the clefts within the first 7 days, and cellular ingrowth was appreciated at 5 to 7 days. By 7 days the artery was repaired, and the histologic appearance of the arteries that had undergone PTCA could not be differentiated from the arteries that had undergone DA. Increased intimal and medial collagen and elastin was noted at 14 and 28 days. An increase in the area bordered by the external elastic lamina was observed in both groups. Although successful DA results in tissue removal and the production of a deep tissue cleft and PTCA causes a dissection, both produce a condition in which the arterial injury exposes the arterial media to blood, causing thrombus formation and inflammation with subsequent cellular accumulation into the thrombotic framework.

Exercise echocardiography, angiography, and intracoronary ultrasound after cardiac transplantation

Fifty-one consecutive patients underwent exercise echocardiography, angiography, and intracoronary ultrasound (ICUS) 2.5 years (range from 1 to 6) after cardiac transplantation. The average age of the donor was 29 years (range 13 to 50), and the average age of the recipient was 49 +/- 12 years. In total, 78 studies were performed, as 25 patients had >1 annual evaluation and 2 patients had 3 consecutive annual evaluations. Of the 78 angiographic studies, 40 (26 patients) had evidence of coronary artery disease, defined as a focal stenosis (>20%, n=4) or luminal irregularities (n=36). However, by ICUS all 51 patients had intimal thickening at some point, with 34 patients possessing diffuse disease and 17 focal intimal thickening only. Of the 25 serial studies, 12 progressed by at least 1 Stanford class. The sensitivity of angiography for determination of class III to IV intimal thickening was 64% and the specificity was 76%. On exercise echocardiography, 6 examinations revealed resting wall motions abnormalities, whereas 6 had inducible wall motion abnormalities with exercise. The sensitivity of exercise echocardiography to determine class III to IV intimal thickening was 15%, and the specificity was 85%. In conclusion, exercise echocardiography is an insensitive method for predicting transplant-mediated coronary artery disease, whereas luminal irregularities on angiography may predict the presence of Stanford grade III to IV intimal thickening.

Microparticle deposition in periarterial microvasculature and intramural dissections after porous balloon delivery into atherosclerotic vessels: quantitation and localization by confocal scanning laser microscopy

Local delivery of pharmacologic or genetic agents with a porous balloon catheter offers a potential therapeutic approach to reducing restenosis and atherosclerosis and minimizing undesirable systemic toxicity. However, the delivery efficiency and intramural retention of liquid agents is low. The local intramural delivery and prolonged retention of 5 microns microparticles (MP) has been described previously. The current study was designed to evaluate the distribution of locally delivered MPs and to determine the effects of MP size and infusion pressure on intramural delivery efficiency. A 1% suspension of fluorescent, latex MPs (1 or 4.5 microns in diameter) was infused at either 3 or 6 atm into atherosclerotic rabbit femoral arteries (n = 32) immediately after angioplasty. Four groups of arteries were evaluated: 1) 1 micron MPs infused at 3 atm; 2) 1 micron MPs at 6 atm; 3) 4.5 microns MPs at 3 atm; and 4) 4.5 microns MP at 6 atm. The location of MPs was evaluated by fluorescent and light microscopy and confocal laser scanning microscopy. The tissue was dissolved and the delivered MPs quantified. All groups manifested numerous MPs within the vasa vasorum and periadventitial microvasculature, with a substantially lesser number within the neointimal and medial layers. The intramural deposition of the MPs was associated with dissection within the intima or media caused by the antecedent angioplasty or local delivery, indicating that an intact vessel wall is an anatomic barrier to MP delivery. The median values of fractional intramural delivery, defined as the percentage of infused MPs retained within the arterial wall, were 0.059%, 0.071%, 0.047%, and 0.062% for the groups 1 through 4, respectively (p not significant [NS]). The values of intramural particle concentration, expressed as the total number of MPs per weight of arterial tissue, were 55, 65, 1.5, and 1.2 x 10(4) MPs/mg for groups 1 through 4, respectively (p < 0.001 for 1 micron vs 4.5 microns MPs). Although more 1 microM MPs were delivered than 4.5 microns MPs, the fractional intramural delivery was unaffected by particle size or infusion pressure. The local delivery of MPs at atherosclerotic sites after angioplasty is characterized by fractional intramural delivery values similar to values of nonparticulate agents, with few MPs deposited into intima or media in the absence of a dissection caused by the antecedent angioplasty or the delivery procedure itself.

Transthoracic echocardiographic detection of coronary atherosclerosis

Coronary atherosclerosis is a pathologic process that produces thickening of the walls of the coronary arteries to the point that flow through those vessels may be impaired. This study attempts to use transthoracic echocardiography to detect coronary atherosclerosis. Eighty-nine patients undergoing coronary angiography were examined with a broad-band ultrasonic transducer with a frequency between 3 and 5 MHz. A modified short axis examination was utilized to identify left main and proximal left anterior descending arteries. The examination was recorded digitally and displayed in a 32-cell, quad screen cine loop. Fifty-six of the 89 patients (63%) had obstructive coronary artery disease (CAD) (i.e, at least 1 vessel with 50% obstruction). There were 14 patients with CAD but no vessel had > or = 50% obstruction. Nineteen patients (21%) had angiographically normal arteries. The coronary echograms were judged qualitatively for brightness, uniformity, and persistence (defined as the ability to see segments of the artery walls in more frames than other segments). The length of the coronary artery visualized, the width of the left main coronary artery, and the width of the thickest segment of the coronary artery walls were quantitatively measured. More than 2 cm of the left coronary artery was seen in almost all patients. Segmental changes were noted in 52 of the 56 patients with obstructive CAD, 12 of the 14 patients with nonobstructive CAD, and 3 of the 19 patients with normal arteries. Persistence greatly enhanced the ability to judge the segmental changes. Forty-six patients with obstructive disease had wall thickness > or = 1.5 mm. Only 6 patients with nonobstructive coronary arteries had this wall thickness, and only 1 normal subject had thick walls. The ultrasonic findings were useful in predicting the presence or absence of coronary atherosclerosis to varying degrees of sensitivity and specificity based on the segmental findings and wall thickness measurements. The results of this study indicate that a transthoracic ultrasonic examination of the proximal left coronary artery could be a clinically valuable tool in the qualitative identification of coronary atherosclerosis.

Local delivery of biodegradable microparticles containing colchicine or a colchicine analogue: effects on restenosis and implications for catheter-based drug delivery

OBJECTIVES

This study sought to evaluate the delivery efficiency, intramural retention and antirestenotic efficacy of soluble colchicine or colchicine analogue delivered into the arterial wall after angioplasty as well as the efficacy of these medications after prolonged local release from biodegradable microparticles.

BACKGROUND

Local delivery of pharmacologic agents is a potential treatment for restenosis. However, the delivery efficiency of the technique and the choice of agent to modulate cellular proliferation are unknown. It was hypothesized that restenosis would be unaffected by colchicine or a hydrophobic colchicine analogue with short intramural retention, whereas it would be reduced after prolonged local release.

METHODS

Rabbit atherosclerotic femoral arteries underwent angioplasty followed by local delivery. Delivery efficiency and intramural retention of 3H-colchicine were evaluated. The effect of agents in soluble formulation or released from microparticles on angiographic and morphometric restenosis was evaluated at 2 weeks and compared with that in the control groups (angioplasty only and local infusion of carrier solution).

RESULTS

Delivery of efficiency was 0.01% and intramural retention < 24 h. Neither soluble colchicine formulation reduced restenosis. Microparticles releasing the colchicine analogue reduced restenosis compared with control and colchicine microparticles but not angioplasty alone (p = 0.002). Delivery outside the artery was observed, and the long-term release of both colchicine resulted in toxicity to the adjacent musculature.

CONCLUSIONS

Colchicine or the colchicine analogue did not reduce restenosis, although the long-term local release of the colchicine analogue reduced neointimal proliferation resulting from local delivery. Local delivery of cytotoxic agents with insufficient vascular specificity may be limited by toxicity to adjacent tissues resulting from a larger than expected delivery area and prolonged agent retention.

Vascular injury, repair, and restenosis after percutaneous transluminal angioplasty in the atherosclerotic rabbit

BACKGROUND

Several nonatherosclerotic animal models of restenosis exist and are used for the evaluation of the vascular response to angioplasty-induced injury. However, few studies have evaluated the response of an atherosclerotic vessel to angioplasty. The present study examined the radiographic, histological, immunohistochemical, and morphometric responses over time of atherosclerotic rabbit femoral arteries after percutaneous transluminal angioplasty (PTA).

METHODS AND RESULTS

Rabbits (n = 94) underwent arterial dissection and were fed a hypercholesterolemic diet for 3 weeks, and then PTA was performed. Arteries were obtained before PTA and 1, 3, 5, 7, 14, and 28 days after PTA. PTA caused radial stretching of the artery, medial compression, intramural hemorrhage, injury to normal arterial segments, and dissection within the intima and media. Thrombus filled and cellular accumulation repaired the dissection. Peak smooth muscle cell and macrophage DNA synthesis was noted at 3 to 5 days after angioplasty, generally at the dissection but also in normal sections of the artery. Adventitial injury and subsequent adventitial cellular proliferation and collagen production were observed. A rapid decrease in the radiographic minimal luminal diameter was noted at 3 days, resulting from vascular recoil or thrombus filling the dissection. At 7 to 14 days, only 24% to 33% of the luminal loss was accounted for by an increase in the intimal area, and 22% to 28% of the intima was neointima.

CONCLUSIONS

Restenosis in an atherosclerotic artery results from a variable combination of intimal proliferation, vascular remodeling/wound contraction, and recoil of the normal section of the artery. The variability of an atherosclerotic artery to PTA injury results from variable dissection, thrombus formation, and cellular response to injury as well as variable scar contraction and elastic recoil.

Peripheral vascular complications following coronary interventional procedures

We report the incidence, diagnosis, prevention, and treatment of peripheral vascular complications following coronary interventional procedures as reviewed in the English-language literature. Peripheral vascular complications include hematomas, pseudoaneurysms, arteriovenous fistulae, acute arterial occlusions, cholesterol emboli, and infections that occur with an overall incidence of 1.5-9%. Major predictors of such complications following coronary interventional procedures include advanced age, repeat percutaneous transluminal coronary angioplasty, female gender, and peripheral vascular disease. Minor predictors include level of anticoagulation, use of thrombolytic agents, elevated creatinine levels, low platelet counts, longer periods of anticoagulation, and use of increased sheath size. Ultrasound-guided compression repair of pseudoaneurysms and arteriovenous fistulae are discussed, as are newer methods of treatment such as hemostatic puncture closure devices. Anticipation and early recognition of possible peripheral vascular complications in conjunction with careful attention to the optimal activated clotting time for sheath removal following coronary interventional procedures may translate into fewer vascular complications as well as into shorter and less costly hospital stays.

Regional and arterial localization of radioactive microparticles after local delivery by unsupported or supported porous balloon catheters

Catheter-mediated intramural delivery of pharmaceutical agents after angioplasty is a potential method to reduce postangioplasty restenosis. The efficacy of such delivery has been limited both by an incomplete initial intramural deposition of delivered agents and by rapid diffusion of soluble agents from the site of delivery. The local delivery of microparticulate agents results in prolonged retention of material at the delivery site. Accordingly this study was designed to evaluate the complementary issue of the initial delivery efficiency and pattern of localization of microparticles after local catheter-mediated delivery with two types of porous balloons. These two types were a "standard" porous balloon (PB) in which hydraulic pressure both inflated the balloon and infused the agents and a porous balloon with a mechanical undergirding that permitted mechanical expansion (PB/ME) before agent infusion. Radioactive cerium 141-labeled microparticles (11.4 microns diameter) were locally delivered into atherosclerotic rabbit femoral arteries after angioplasty to test the hypothesis that use of the PB/ME apparatus would yield enhanced intramural particle deposition and decreased systemic administration by increased balloon-wall contact before microparticle infusion. Six animals underwent infusion with the PB catheter, and seven animals underwent infusion with the PB/ME catheter. An image of the in vivo particle distribution was obtained with a gamma camera during infusion, immediately after infusion, and 1, 3, and 7 days after infusion. Tissue samples from the artery, periadventitia, thigh, calf, and foot musculature, and liver were obtained at animal death, and retained radioactivity was measured with a well counter.(ABSTRACT TRUNCATED AT 250 WORDS)

Thromboembolism in patients with decreased left ventricular function: incidence, risk, and treatment

Intracavitary thrombus is noted in 11-44% of patients with idiopathic delayed cardiomyopathy, and the incidence of embolism is 11-20%. The incidence of intracavitary thrombus formation after acute anterior myocardial infarction is 21-41%. The risk of embolism in all patient with acute anterior myocardial infarction is 2-6%; protruding or mobile thrombi carry a risk of embolization. Systemic anticoagulation is justified in patients with dilated cardiomyopathy (international normalized ratio 2.0-3.0).

Biodegradable microspheres containing a colchicine analogue inhibit DNA synthesis in vascular smooth muscle cells

BACKGROUND

Smooth muscle cell proliferation plays a major role in the genesis of restenosis after angioplasty or vascular injury. Local application of agents capable of modulating vascular responses, including smooth muscle cell proliferation, has been achieved, but difficulty in maintaining active levels locally has been a factor limiting the efficacy of such approaches. One strategy to maintain adequate levels is the local delivery of microspheres that release active agents over sustained time periods.

METHODS AND RESULTS

We incorporated a colchicine analogue into biodegradable microspheres composed of a lactic acid/glycolic acid copolymer and characterized their drug release behavior as well as their effects on bovine aortic smooth muscle cells (BASMCs) in culture. Drug release was evaluated by spectrophotometric assay. Drug effects on DNA synthesis were measured by thymidine incorporation after addition of serum to subconfluent cells synchronized by serum withdrawal as well as in asynchronous cell populations. Polymeric microspheres incorporating 10% to 17% drug by weight and averaging 6 microns in size were found to release the colchicine analog in buffered saline solutions over more than several weeks. Drug-loaded particles inhibited DNA synthesis completely, with EC50 values ranging from 0.001 to 0.005 g% (wt/wt). Morphological changes suggesting microtubule depolymerization were observed after drug particle treatment, with similar EC50 values. Microspheres allowed to contact the cell surface demonstrated effects similar to those seen with microspheres suspended in the nutrient medium by porous polycarbonate filters, at EC50 values approximately fivefold lower. In contrast, control microspheres composed only of polymer with no incorporated active drug demonstrated no observable toxicity to BASMCs and < 40% inhibition of thymidine incorporation even in suspensions containing up to 0.5 g% particles.

CONCLUSIONS

Biodegradable microspheres were fashioned that release a colchicine analogue and inhibit DNA synthesis in smooth muscle cells. Drug-loaded polymeric particles are candidates for local delivery at sites of arterial injury to decrease restenosis.

Intracoronary artery thrombus formation in unstable angina: a clinical, biochemical and angiographic correlation

OBJECTIVES

We examined the relation between the level of urinary fibrinopeptide A and the presence of angiographic intracoronary thrombus in patients with unstable angina to determine whether this marker predicts active thrombus formation.

BACKGROUND

Although it is known that thrombus plays a role in acute ischemic syndromes, a noninvasive method to predict its presence in individual patients with unstable angina has not been determined. Fibrinopeptide A is a polypeptide cleaved from fibrinogen by thrombin and thus is a sensitive marker of thrombin activity and fibrin generation.

METHODS

Angiographic thrombus, graded 0 to 4, and the presence of ST segment depression or T wave inversions, or both, on the electrocardiogram (ECG) were related to fibrinopeptide A levels in 24 patients with rest angina of new onset, 18 with crescendo angina, 19 with stable angina and 9 with chest pain but without coronary artery disease. All patients had chest pain within the 24 h of sample acquisition.

RESULTS

The angiographic incidence of thrombus was significantly higher in patients with new onset of rest angina (67%, p < 0.001) and crescendo angina (50%, p < 0.001) as were fibrinopeptide A levels (p = 0.002). Fibrinopeptide A levels correlated significantly (p < 0.001) with the presence of a filling defect (grade 4 intracoronary thrombus) or contrast staining (grade 3). All patients with fibrinopeptide A > or = 8 ng/mg creatinine showed grade 3 to 4 thrombus and 15 of 16 patients with levels > or = 6.0 ng/mg creatinine exhibited angiographic evidence of thrombus (13 with grades 3 to 4). Patients with reversible ST changes on the ECG had significantly higher levels of fibrinopeptide A (p < 0.001), and ST changes correlated significantly with the presence of angiographic thrombus (p < 0.001). Nonetheless, a significant minority of patients with unstable angina had neither angiographic nor biochemical evidence of thrombus.

CONCLUSIONS

Elevated fibrinopeptide A levels in unstable angina reflected active intracoronary thrombus formation and were present in patients with angina of new onset as well as crescendo angina. Reversible ST changes are accompanied by thrombin activity and angiographic thrombus formation. However, a sizable percentage of patients with unstable angina had no evidence of thrombus and these patients may have had transient platelet aggregation without fibrin thrombus formation.

Effects of thiol protease inhibitors on cell cycle and proliferation of vascular smooth muscle cells in culture

Smooth muscle proliferation is a prominent feature of the vascular response to mechanical injury. Accordingly, modulation of proliferation has important therapeutic implications for angioplasty restenosis. We have identified a subclass of thiol protease inhibitors (TPIs) that reversibly inhibit bovine aortic smooth muscle cell (BASMC) proliferation in vitro. To define the nature of this inhibition, an evaluation of selected steps in the cell cycle was undertaken. Treatment of BASMCs with benzyloxycarbonyl-Leu-norleucinal (calpeptin) at 100 microM and acetyl-Leu-Leu-norleucinal (TPI-1) at 50 microM was shown to cause a block of platelet-derived growth factor-BB as well as serum-inducible cell cycle progression at a point before the G1-S boundary, reducing the percentage of bromodeoxyuridine-positive cells from 87% to 5% over a 24-hour labeling period. Addition of TPI-1 at various times after serum addition to serum-deprived BASMCs showed 80% of the maximal block of DNA synthesis even when added 6 hours after serum. The cell cycle progression block was gradually lost as the delay from serum to TPI-1 application was increased from 6 to 12 hours. By Northern analysis of mRNA after serum addition, TPI-1 caused a fourfold decrease in the transient elevation of fos and myc proto-oncogene as well as a decrease in the levels of both muscle and nonmuscle actin mRNA induced early after serum addition. Flow cytometric analysis of DNA content and synthesis in BASMCs treated with TPI-1 or calpeptin additionally revealed the presence of a distinct cell cycle block in the G2-M compartment. In the aggregate, these results suggest the existence of more than one molecular site potentially involved in inhibition by TPI of cell cycling in BASMCs.

8-Methoxypsoralen and longwave ultraviolet irradiation are a novel antiproliferative combination for vascular smooth muscle

BACKGROUND

Smooth muscle cell proliferation plays a major role in the genesis of restenosis after angioplasty or vascular injury. Although the effects of arterial exposure to high-energy radiation sources such as laser have been investigated in detail, the effects on vascular cells of low-intensity radiant energy in combination with photoactive agents have not been extensively characterized. Psoralens are photoactive agents that are known to be well tolerated when used in conjunction with local exposure to ultraviolet light in the A band (UVA) for the treatment of various dermatologic proliferative disorders.

METHODS AND RESULTS

We have investigated the effects of psoralen/UVA (PUVA) exposure on the proliferation of bovine aortic smooth muscle cells. Proliferation and viability were assessed over a 14-day period by trypan blue exclusion counts. Cell cycle effects were evaluated by thymidine incorporation and flow cytometry with DNA quantitation after addition of serum or platelet-derived growth factor B-chain (PDGF-BB) to subconfluent cells synchronized by serum withdrawal. No effect was observed after exposure to 8-methoxypsoralen (8-MOP) at concentrations up to 10 microM or UVA irradiation at energies up to 2.5 J/cm2. Longwave ultraviolet light and 8-MOP were found to behave synergistically as potent inhibitors of DNA synthesis in bovine aortic smooth muscle cells with the EC50 in combination ranging from 7 microM at 0.35 J/cm2 to 0.2 microM at 2.1 J/cm2. Similar antiproliferative effects were obtained by an inverse variation of dose and energy delivered. After serum stimulation, inhibition of DNA synthesis was found with either an immediate or delayed (16-hour) application of PUVA. This effect was independent of subsequent 8-MOP washout. Flow cytometry of cells treated with PUVA at several times after serum stimulation demonstrated for each time point a block in further cell cycle progression for cells in all phases of the cell cycle. Evaluation of [125I]-labeled PDGF and epidermal growth factor (EGF) binding revealed no effect of PUVA on the apparent number or affinity of PDGF binding sites present but did reveal a dose-dependent inhibition by PUVA of EGF binding. This inhibition of EGF binding occurred increasingly at higher PUVA doses than the cell cycle inhibition and accordingly did not appear to represent a critical mechanism for the antiproliferative effect. Cell counting after a single exposure to PUVA (1 microM, 1.5 J/cm2) revealed complete stasis of cell proliferation over a 28-day period without recurrent exposure. No increase in trypan-positive cells was noted over this period.

CONCLUSIONS

PUVA treatment represents a novel method for locally inhibiting proliferation of vascular smooth muscle cells without producing cytolysis.

Direct intraarterial wall injection of microparticles via a catheter: a potential drug delivery strategy following angioplasty

Local delivery into the arterial wall of medications at high concentrations may evolve as a method to reduce postangioplasty restenosis. However, since the atherosclerotic artery has increased vasa vasorum, medications injected in a fluid state may diffuse out of the arterial wall too quickly to have a therapeutic effect. Thus we evaluated whether microparticles as a model for a particulate microcarrier drug delivery system, injected via a porous balloon catheter, could be retained within the atherosclerotic rabbit femoral arterial wall. Arteries were injected with a 5 microns microparticle suspension for 45 seconds at either 3 or 5 atm of infusion pressure immediately following balloon angioplasty. Arteries were obtained immediately following the procedure or at 1, 3, 7, or 14 days after infusion to evaluate for the presence of retained microparticles. Of 34 arteries, 30 contained retained microparticles, with 21 exhibiting microparticles in the neointimia, 12 in the media, and 25 in the adventitia. Microparticles were retained for as long as 14 days, and there was no difference between the distribution or quantity of microparticles at 3 or 5 atm of infusion pressure. The mode of microparticle distribution probably involved deposition within dissection planes, although evidence for vasa vasorum transport was observed. We hypothesize that biodegradable microparticles could serve as a vehicle for intramural drug delivery in the treatment of restenosis.

Restrictive hemodynamic patterns after cardiac transplantation: relationship to histologic signs of rejection

Hemodynamic and echocardiographic data from 33 consecutive patients undergoing cardiac transplantation were correlated with endomyocardial biopsy results to determine whether reversible restrictive hemodynamics accompany histologic evidence of transplant rejection. During the study period 251 biopsy specimens were obtained during periods of no histologic evidence of transplant rejection and 52 episodes of mild, 20 episodes of moderate, and one episode of severe rejection. Right atrial mean pressure increased significantly during episodes of moderate transplant rejection (9.9 +/- 6.2 mm Hg, p less than 0.001) compared with pressures obtained during periods when there was no evidence of rejection (4.6 +/- 3.2 mm Hg), mild rejection (5.8 +/- 3.9 mm Hg), or resolving rejection (4.3 +/- 3.4 mm Hg). Y descent was elevated during moderate rejection (9.6 +/- 4.2 mm Hg, p less than 0.001) compared with pressures during episodes of no rejection (5.6 +/- 2.5 mm Hg), mild rejection (6.6 +/- 2.7 mm Hg), and resolving rejection (5.8 +/- 3.1 mm Hg) and showed a wave morphology consistent with a restrictive hemodynamic pattern. Pulmonary capillary wedge pressure was increased during moderate rejection (14.4 +/- 6.4 mm Hg) when compared with pressures obtained during episodes of no rejection (10.2 +/- 5.8 mm Hg) or resolving rejection (10.2 +/- 5.4 mm Hg) (p less than 0.02). Sensitivity for a right atrial mean pressure of 11 mm Hg indicating moderate rejection was 41% with a specificity of 96%. Sensitivity for Y descent (greater than or equal to 10 mm Hg) was 52% and specificity was 94%.(ABSTRACT TRUNCATED AT 250 WORDS)

Urinary fibrinopeptide A levels in ischemic heart disease

Because acute coronary thrombosis can cause unstable coronary artery disease, fibrinopeptide A, a reliable marker of coagulation activity, may play a role in the evaluation of unstable ischemic syndromes. A new method of fibrinopeptide A sampling, spot urine normalized to urinary creatinine, was evaluated in patients with stable and unstable angina pectoris and acute myocardial infarction. Serial samples were obtained to characterize the changes in urinary fibrinopeptide A levels over time in patients with ischemic heart disease. Admission values (mean +/- SD) were similar in the control group (3.3 +/- 1.4 ng/mg creatinine) and the stable angina group (3.2 +/- 1.1 ng/mg creatinine) (p = NS). Values in the unstable angina group (5.7 +/- 2.6 ng/mg creatinine) were higher than those in the control (p = 0.008) and stable angina (p less than 0.001) groups. Myocardial infarction admission values (8.4 +/- 10.0 ng/mg creatinine) were higher than those in the control (p = 0.005) and stable angina (p less than 0.001) groups, but not higher than those in the unstable angina group. Peak values (the highest of multiple samples) were higher in the unstable angina group (7.6 +/- 5.9 ng/mg creatinine) than in the stable angina group (4.0 +/- 1.0 ng/mg creatinine) (p = 0.04), but not in the control group (4.5 +/- 1.9 ng/mg creatinine) (p = 0.056). The two patients with unstable angina with the highest peak values subsequently exhibited infarction. Peak values in patients with infarction (44.5 +/- 60.0 ng/mg creatinine) were significantly higher than those in patients with unstable (p = 0.03) or stable (p = 0.002) angina and control patients (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Serial electrocardiographic changes in idiopathic dilated cardiomyopathy confirmed at necropsy

Serial electrocardiographic changes in necropsy-proven idiopathic dilated cardiomyopathy are evaluated and a method of predicting heart weight using QRS amplitudes is described. In 34 patients with multiple electrocardiograms (mean 3/patient) progressive prolongation of PR interval (0.18 +/- 0.03 to 0.21 +/- 0.03, p less than 0.001) and QRS duration (0.10 +/- 0.02 to 0.13 +/- 0.03, p less than 0.0001) was noted. Progressive conduction abnormalities were common (82%). QTc interval and QRS- and T-wave axes did not change. In 50 patients with electrocardiograms within 60 days of death, total 12-lead QRS and V1 through V6 QRS amplitude correlated better with heart weight (r = 0.51, p less than 0.0001 and r = 0.55, p less than 0.0001) than the Estes-Romhilt score did. The mean total 12-lead QRS amplitude was 138 mm with a mean of 106 for V1 through V6. In 31 patients cardiac mass index was calculated and showed significant correlation with 12-lead and V1 through V6 QRS amplitudes (r = 0.68, p less than 0.0001 and r = 0.75, p less than 0.0001, respectively). The QRS amplitudes remained constant during the illness. By using total 12-lead QRS or frontal plane QRS amplitude, heart weight can be predicted as early as 2 years before death. Use of body surface area and QRS amplitude criteria increases the accuracy of heart weight prediction. Thus, progressive electrocardiographic changes are common in patients with idiopathic dilated cardiomyopathy and QRS amplitude criteria are more accurate in the prediction of left ventricular hypertrophy than standard criteria.

Iliofemoral thrombophlebitis presenting as an acute abdomen: report and literature review

Iliofemoral thrombophlebitis characteristically presents as acute inflammation and swelling of the affected extremity. We report a patient in whom the presenting complaints of high fever, nausea and left lower quadrant pain mimicked an acute abdomen. The diagnosis was confirmed by venogram after gallium scan and computer tomographic scan revealed abnormalities consistent with iliofemoral thrombophlebitis. This is the first report of abnormal gallium uptake in iliofemoral thrombophlebitis. Current methods of diagnosing this disorder are discussed and the literature reviewed.

The subendocardial border zone during acute ischemia of the rabbit heart: an electrophysiologic, metabolic, and morphologic correlative study

Isolated preparations of rabbit interventricular septum were perfused through the coronary arteries with oxygenated Tyrode's solution and placed in a tissue bath where they were superfused as well. Transmembrane potentials were simultaneously recorded from the subendocardium with two flexibly mounted microelectrodes, one from a superficial cell, and the other from a deep cell. Ischemia was produced by stopping coronary flow while superfusion with oxygenated Tyrode's solution was maintained. After a 7 to 12 min ischemic period, the preparation was fixed by coronary perfusion with fixative while the microelectrodes remained in place. After fixation, the microelectrodes were withdrawn. Appropriate tissue blocks were cut in 4 micron serial sections and the microelectrode track was followed until the tip position was identified. Transmembrane potentials during ischemia were divided into two categories: "border zone" potentials (resting membrane potential [RMP] 73 +/- 3 mVe, action potential amplitude [APA] 81 +/- 13 mV, action potential duration [APD] 116 +/- 48 msec, n = 12) and "ischemic" potentials (RMP 53 +/- 4 mV, APA 44 +/- 11 mV, APD 102 +/- 42 msec, n = 8). Ischemic potentials were recorded from cells at depths greater than 560 micron below the endocardial surface and border zone potentials were recorded in a layer at between 130 and 650 micron below the surface. In a separate series of experiments, extracellular concentrations of K+ and pH were measured with ion-sensitive electrodes at different depths and, after a 10 min period of ischemia, part of the septum was placed in liquid nitrogen to allow determination of phosphocreatine (PC) levels in successive 50 to 100 micron layers. After 10 min of ischemia, extracellular K+ gradually increased from 4 to 9 mM in endocardium to a depth of 600 micron, pH fell from 7.4 to 6.6 over the same distance, and PC decreased to very low, stable levels at only 800 micron. It is concluded that in the first 10 min of acute ischemia, an endocardial border zone exists of 40 to 60 cell layers in which transmembrane potentials are affected relatively little by ischemia. Within this electrophysiologic border zone extracellular K+ was lower than 9 mM, pH was higher than 6.6, and tissue content of PC was not lower than 40% of normal. In layers deeper than 600 micron, with further development of a metabolic gradient, action potentials became markedly depressed. This electrophysiologic inhomogeneity within the ischemic subendocardium could be a factor in arrhythmogenesis during the first minutes of ischemia.