Electrowetting in a water droplet with a movable floating substrate.

Electrowetting (EW) enables facile manipulation of a liquid droplet on a hydrophobic surface. In this study, manipulation of an electrolyte droplet having a small floating object on it was investigated on a solid hydrophobic substrate under the EW process. Herein, the floating object exhibited a vertical motion under an applied electric field owing to the spreading and contraction of the droplet on its connecting substrates. The field-induced height variation of the floating object was significantly influenced by the thicknesses of the dielectric and hydrophobic materials. A small mass was also placed on the top floating object and its effect on the spreading of the droplet was observed. In this system, the height of the top floating object is precisely controllable under the application of an electric voltage. The proposed system is expected to be highly useful in the design of nano- and micro-oscillatory systems for microengineering.

Influence of vessel diameter on the efficacy of distal protection devices during saphenous vein graft intervention.

We sought to determine the influence of vessel diameter on the efficacy of distal protection devices during saphenous vein graft intervention. From the Filterwire EX Randomized Evaluation trial, in which patients who underwent saphenous vein graft stenting were randomized to distal protection with the GuardWire or FilterWire EX, outcomes in 572 patients were examined in vessel size tertiles. The 30-day composite incidence of major adverse cardiac events (MACEs) increased with vessel size and was 6.9%, 9.7%, and 14.9% in the smallest, middle, and largest tertiles, respectively (p = 0.04). MACE rates were relatively vessel size independent for the GuardWire but increased steadily with vessel size with the FilterWire EX. In the smallest tertile, MACEs were reduced by 71% with the FilterWire EX compared with the GuardWire (p = 0.05), with the devices showing similar event rates in the other tertiles.

Mitral regurgitation in coronary artery disease.

Over a period of 5.25 years, 1,530 patients with coronary artery disease (CAD) underwent catheterization; 104 had associated mitral regurgitation (MR), and 60 had no complications. Twelve patients underwent coronary artery bypass graft surgery (CABG), with both pre- and postoperative angiograms. Nine of the 12 patients (75 percent) were in functional class 3 or 4. Left ventricular ejection fraction ranged from 34 to 75. The MR was considered severe (3+) in three, moderate (2+) in six, and trivial (1+) in three patients. Following CABG, all except two patients were in class 1. Of the 43 patients medically treated, 31 patients (72 percent) were in functional class 3 or 4. Angiographic results showed that five patients had 3+ MR, 14 had 2+ MR, and 24 had 1+ MR. The EF was less than 30 in 23 patients and greater than or equal to 30 in 20 patients, and left ventricular filling pressure was elevated. Twenty patients died, with a mean follow-up period of 11 months. Our study demonstrates that the surgically treated patients showed angiographic improvement in MR, improved functional status, and relief of symptoms compared with medically treated patients. We believe that a subset of patients with MR and CAD would benefit with CABG.

Perioperative myocardial infarction: a diagnostic dilemma.

Patients undergoing coronary bypass grafting were studied for incidence of perioperative myocardial infarction (MI) using three modalities: serial electrocardiograms (ECG), serial creatine phosphokinase isoenzymes (MB-CPK), and serial technetium 99m-labeled pyrophosphate scans. A definite perioperative MI was diagnosed if the results were positive in two of the three variables studied. The perioperative infarction rate for the entire group was 8%. The operative mortality was 2.9%. Seven of 8 perioperative MIs were diagnosed by the use of scanning alone. The combination of isoenzyme and ECG analysis diagnosed 5 of 8 perioperative MIs. The MB-CPK and ECG studies were associated with a higher incidence of false-positive diagnoses than myocardial scanning. Patients with perioperative MI had a benign clinical course. Justification for performing three routine 99mTc-pyrophosphate scans on all patients undergoing aortocoronary bypass operation is still to be determined.

Improved exercise performance following single daily dose of atenolol in stable angina.

We administered atenolol to 10 patients with effort limiting angina pectoris. Doses of 50 mg, 100 mg and 200 mg provided significant improvement (P less than 0.05) in exercise tolerance tested 24 hours after the drug was given. Twenty-five milligrams was not significantly better than placebo in increasing work tolerance. Side effects were minimal, and treatment could be continued throughout the study. The beta-blocker atenolol is an effective drug in the treatment of exercise-induced angina.

Vascular responses to the multiple overlapped paclitaxel-eluting stents for the treatment of bare-metal in-stent restenotic lesions: angiographic and intravascular ultrasound analysis from the TAXUS-V ISR trial.

BACKGROUND: Although effective coverage of coronary diffuse in-stent restenosis (ISR) lesions has warranted the use of multiple drug-eluting stents, the vessel response to paclitaxel-eluting stent (PES) overlap is not fully understood. METHODS AND MATERIALS: In the TAXUS-V ISR, i.e., comparing PES versus brachytherapy for the treatment of bare-metal ISR, angiographic analyses at 9-month follow-up were available in 184 ISR lesions treated with PES. RESULTS: In-stent late loss in entire stented segment of multiple PES (n=50) was 0.45+/-0.48 mm, whereas that of single PES (n=134) was 0.3+/-0.47 mm, P=.06. No aneurysm was observed at overlapping PES segments at 9 months. Stent thrombosis up to 9 months was observed in one in each group (single PES, 0.7% vs. multiple PES, 1.8%; P=.47). In a subset of 30 patients, volumetric intravascular ultrasound analysis demonstrated that in-stent net volume obstruction was 12.3+/-12.4 in single PES (n=20) and 14.9+/-9.8 in multiple PES (n=10), P=.60. The changes of vessel and lumen at the overlapping PES segment were similar to those of the adjacent 5-mm segments (Deltaminimum lumen area, mm(2): -1.2+/-1.0, -1.1+/-1.1, -0.8+/-0.9, P=.48; Deltavessel volume, mm(3)/mm: -0.2+/-1.4, 0.1+/-1.7, 0.3+/-1.3, P=.37; proximal, overlap, distal segment, respectively). There was no late incomplete stent apposition at overlapping PES segments. CONCLUSIONS: No in vivo evidence of adverse local vessel response at the site of overlapping PES for the treatment of bare-metal ISR has been demonstrated.

Chronic arterial responses to overlapping paclitaxel-eluting stents: insights from serial intravascular ultrasound analyses in the TAXUS-V and -VI trials.

OBJECTIVES: The purpose of this study was to use intravascular ultrasound (IVUS) to investigate chronic arterial responses at the site of and adjacent to overlapping paclitaxel-eluting TAXUS stents (PES) compared with overlapping bare-metal stents (BMS). BACKGROUND: Increased paclitaxel dose in the PES-overlap region might be associated with arterial toxicity expressed as excessive expansive remodeling, incomplete stent apposition, or aneurysm formation. METHODS: In the TAXUS-V and -VI trials, 51 patients with overlapping stents (27 PES and 24 BMS) were imaged with serial IVUS immediately after procedure and at 9 months. The IVUS measurements included intimal hyperplasia (IH), peri-stent plaque plus media (P&M), and external elastic membrane (EEM) areas. Vascular responses were assessed at the proximal and distal single stent strut regions and the central overlap region. RESULTS: Compared with BMS, all 3 PES stent regions showed: 1) significantly decreased IH (proximal: 0.97 +/- 1.06 mm(2) vs. 3.12 +/- 2.40 mm(2), overlap: 0.74 +/- 0.91 mm(2) vs. 3.23 +/- 1.75 mm(2), distal: 0.88 +/- 0.85 mm(2) vs. 2.69 +/- 1.49 mm(2), all p < 0.05); and 2) increased P&M and EEM areas (Delta P&M, proximal: 0.96 +/- 1.36 mm(2) vs. -0.02 +/- 1.48 mm(2), overlap: 1.56 +/- 1.88 mm(2) vs. 0.29 +/- 1.82 mm(2), distal: 1.03 +/- 1.81 mm(2) vs. 0.11 +/- 0.89 mm(2), all p < 0.05). The IH and changes in EEM and P&M areas were not significantly different in both the BMS and PES groups comparing the single stent strut and overlap regions. Incomplete stent apposition did not occur at the site of overlapping PES in any patient. CONCLUSIONS: Nine months after stent implantation, neointimal tissue growth was reduced and expansive remodeling was greater with PES compared with BMS--effects that were not exaggerated at the overlap region of PES.

Patterns of myoglobin release after reperfusion of injured myocardium.

Myoglobin is an intracardiac protein that is released into the blood after myocardial injury and is then cleared rapidly by the kidneys. This study was undertaken to determine whether successful reperfusion of damaged myocardium could be assessed by examination of blood myoglobin concentration-time patterns. After release of a 2 hr occlusion of the mid left anterior descending coronary artery in 11 dogs that had been instrumented over the long term, immunoreactive arterial plasma concentration of myoglobin, [Mb], rose rapidly to a peak within 25 +/- 2(SEM) min (range 20 to 40). Individual peaks were three to 165 times the myoglobin levels immediately before release of the occlusion. Myoglobin was cleared rapidly from plasma, falling to one-half its peak level 38 +/- 3 min after the peak. Similarly well-defined peaks in [Mb] were evident in plasma from the great cardiac vein (GCV), with a mean time to peak of 16 +/- 2 min and a magnitude of two to 177 times prerelease values. In contrast, arterial and GCV creatine kinase activity-time curves showed less defined peaks and they occurred later and with more variability (60 to 330 min after reperfusion). In nine patients with acute infarction, successful coronary artery reopening was also accompanied by a sharp four- to sixteenfold rise in plasma [Mb] within 1 to 2 hr. Elevations in plasma creatine kinase were slower and more prolonged, peaking at 2 to 18 hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Early noninvasive detection of successful reperfusion in patients with acute myocardial infarction.

Myoglobin (Mb) is a protein that enters rapidly and is rapidly cleared from plasma after coronary reperfusion. We sought to determine the accuracy with which a rapid rise in plasma [Mb] could predict successful coronary artery reopening in patients undergoing coronary arteriography in conjunction with attempted reperfusion in acute myocardial infarction. In 42 patients, plasma Mb levels were measured before and for at least 4 hours after attempted reperfusion. Thirty-five patients were successfully reperfused. In each, the plasma Mb level rose rapidly with peak [Mb] occurring at 111 +/- 8.1 (+/- SEM) minutes after application of therapy. In contrast, Mb levels rose more slowly in the seven patients who were not reperfused, with peak [Mb] occurring 360 +/- 61.4 minutes after attempted reperfusion. T25-100 (the time required for [Mb] to rise from 25% to 100% of peak value) was shorter in patients successfully reperfused (71 +/- 7.9 minutes) and longer (341 +/- 35.3 minutes) in patients in whom therapy was unsuccessful. A rapid rise in [Mb] after successful reperfusion was also evident by a more than 4.6-fold rise in [Mb] over the first 2 hours after reperfusion in all but five patients; in contrast, [Mb] rose by less than 4.6-fold over this same interval in every patient not successfully reperfused (sensitivity, 85%; specificity, 100%; predictive accuracy, 88%). We conclude that a rapid rise in plasma Mb level over the initial 2 hours after attempted reperfusion in acute myocardial infarction provides a useful index of successful reperfusion.

Compliant vs non-compliant balloons. A prospective randomized study.

In this prospective randomized trial we explored the possibility of different procedural outcomes with regard to compliant (polyolefin copolymer (POC)), and non-compliant (polyethylene terapthelate (PET)) balloon materials commonly used during percutaneous transluminal coronary angioplasty (PTCA). For this purpose, 51 female and 149 male (total 200) patients were randomized to 100 compliant and 100 non-compliant balloons. Only single lesions were included in the study and patients who had PTCA for more than one lesion in different segments at different sessions were each entered separately (there were actually 49 female and 143 male patients). PTCA procedures were performed in conjunction with quantitative coronary angiographic techniques and the films were reviewed by two investigators in a blinded fashion. Statistical analysis for various procedural end-points were performed by non-paired Student t test with statistical significance being p < 0.05. There were no differences in demographic and clinical characteristics between groups. Lesion characteristics of both groups were exactly matching for vessel size, balloon size, balloon vessel ratio, minimal luminal diameter and percent stenosis of the index lesion. Similarly, minimal residual diameter, percent residual stenosis, net gain, densitometric net area gain, and maximum pressure (2.2 +/- 5 mm vs 2.1 +/- 0.6 mm, 18 +/- 17% vs 23 +/- 15%, 0.8 +/- 0.5 mm vs 0.8 +/- 0.6 mm, 48 +/- 25% vs 48 +/- 26%, 7.3 +/- 2 atm. vs 6.8 +/- 3 atm., respectively) values were not statistically different between compliant and non-compliant balloon groups. Major in-hospital complications, dissections caused by the study balloon (mostly type A and B), crossover and bail-out procedures (5 vs 3, 34 vs 32, 4 vs 3, 13 vs 14, respectively) were similar for both compliant and non-compliant balloon groups. Study balloon success rate (defined as < 50% residual stenosis or > 20% net gain in the absence of major in-hospital complications, crossovers and bail-outs) and overall procedural success rate (80% vs 74%, 90% vs 85%) were not statistically different for compliant and non-compliant balloons. In conclusion, we did not observe any statistically significant difference between compliant and non-compliant balloons in terms of immediate procedural results.

Directional coronary atherectomy versus coronary angioplasty in vessels larger than 3 mm in diameter.

It has been proposed that directional coronary atherectomy (DCA) should be an intervention of choice in larger vessels as one can achieve a greater minimal luminal diameter with DCA than with percutaneous transluminal coronary angioplasty (PTCA). This in turn should translate into a higher success rate and may even reduce the restenosis rate. The aim of this study was to compare DCA versus PTCA in vessels > 3 mm in diameter. One hundred fifty consecutive patients who met the inclusion criteria and had DCA were compared to 150 similarly selected PTCA patients. PTCA patients were selected from the era immediately preceding the advent of DCA so that selections bias could be excluded. All patients with ostial lesions, restenosis, vessels < 3 mm in diameter, and vessels with more than two significant lesions were excluded. Distal segments and circumflex cases were excluded as they formed a small subsegment. Both groups were similar in terms of demographic, clinical and angiographic variables. Quantitative analysis showed that the initial net gain was significantly greater in the DCA group than in the PTCA group (2.36 +/- 0.8 mm vs. 1.78 +/- 0.7 mm; p < 0.05). Residual stenosis was 11% with DCA compared to 33% with PTCA (p < 0.05). Despite these improved anatomical results the procedural success rates were similar (91.5% vs 84%). Major in hospital complications (death, acute occlusion, MI, emergency CABG, re-do) were higher in the DCA group than in the PTCA group (12% vs 6%). Clinical follow-up on 276 patients (150 DCA vs 126 PTCA) showed a 6 month clinical restenosis rate of 18% vs 28%, respectively. The incidence of re-do in 24 hours for acute occlusion was 6% for DCA and 1% for PTCA. In large-sized vessels DCA results in a lower restenosis rate. However, despite a lower incidence of residual stenosis, the complication rate tends to be higher with DCA (p < 0.05).

Pharmacodynamic efficacy, clinical safety, and outcomes after prolonged platelet Glycoprotein IIb/IIIa receptor blockade with oral xemilofiban: results of a multicenter, placebo-controlled, randomized trial.

BACKGROUND: Parenteral administration of platelet glycoprotein IIb/IIIa (GP IIb/IIIa) receptor blockers can reduce ischemic complications of coronary angioplasty. Orally active GP IIb/IIIa blockers may allow more sustained receptor antagonism with the potential for long-term secondary prevention. The pharmacodynamic efficacy, clinical safety, and outcomes after prolonged receptor blockade with an orally active GP IIb/IIIa antagonist are not known. The Oral Glycoprotein IIb/IIIa Receptor Blockade to Inhibit Thrombosis (ORBIT) Trial is a multicenter, placebo-controlled, randomized trial of xemilofiban, an oral platelet GP IIb/IIIa blocking agent, administered to patients after percutaneous coronary intervention. METHODS AND RESULTS: After successful elective percutaneous coronary intervention, 549 patients were randomized to receive either placebo or xemilofiban in a dose of 15 or 20 mg. Stented patients randomized to placebo also received ticlopidine 250 mg orally BID for 4 weeks. Patients who received abciximab during the coronary intervention and who were randomized to receive xemilofiban were administered a reduced dosage (10 mg TID for 2 weeks) followed by the randomized maintenance dose of 15 or 20 mg BID for 2 more weeks. All patients received 325 mg aspirin PO QD. Ex vivo platelet aggregation in response to 20 micromol/L ADP and 4 microg/mL collagen was measured over time after the initial dose of study drug and at days 14 and 28 of long-term therapy in 230 patients. All patients were followed clinically for 90 days. Xemilofiban inhibited platelet aggregation to both ADP and collagen with peak levels of inhibition that were similar at 14 and 28 days of long-term oral therapy. Plasma levels of xemilofiban correlated with the degree of platelet inhibition. Peak platelet inhibition on day 1 correlated with the subsequent occurrence of insignificant or mild bleeding events. Although this study was not powered to evaluate differences in clinical outcomes, a trend (P=0.04) was observed for reduction of cardiovascular events at 3 months in patients not treated with abciximab who received the highest dose (20 mg) of xemilofiban studied. CONCLUSIONS: Xemilofiban inhibited platelet aggregation and was well tolerated during 28 days of long-term oral therapy. The observed trend in reduction of cardiovascular events in follow-up awaits confirmation in the larger-scale phase III study (EXCITE trial) currently in progress.