Search PubMed⌕ Search

Biomedical subjects

R E Shaw

Publications and source records attributed to R E Shaw.

At least 19 recordsLinked to original sources
PubMed2000

A process for ensuring optimal cardiovascular intervention and identifying candidates for glycoprotein IIb/IIIa receptor inhibitor therapy.

Data from trials with glycoprotein (GP) IIb/IIIa receptor inhibitors have led to a new standard of care for patients with unstable angina or non-wave myocardial infarction (MI) who are undergoing percutaneous coronary intervention. Additional data are necessary to compare patient responses to various GP IIb/IIIa agents in a nontrial setting with results from clinical trials. Seton Medical Center has designed a database to accommodate this task. Data from >20,000 patients have been collected since 1979 and the interventional experience from the years 1997 through 1999 has been analyzed for patients who were candidates for receiving these agents. The data are being used to evaluate the outcomes of therapy and to devise models that can stratify patients according to risk, thereby ensuring optimal cardiovascular intervention and choice of the most cost-effective GP IIb/IIIa inhibitor agent.

Abciximab↗
PubMed2000

Coronary artery bypass surgery on small patients.

Little research exists on the outcome of smaller patients who undergo coronary artery bypass graft surgery. The purpose of this study was to evaluate the outcomes of cardiac surgery in smaller patients (males with body surface area of 1.6 square meters or less, and women with 1.5 meters or less). A consecutive series of 4,358 patients undergoing bypass surgery was evaluated. Of these, 246 (5.6%) were classified as small patients. Smaller patients were more likely to be women, older and of Asian ethnicity. They were less likely to have undergone a prior cardiac surgery. Smaller patients were less likely to receive an arterial conduit (74% versus 99%; p<0.00001). Rates of post-surgery complications differed between small and normal size patients, with smaller patients more likely to require prolonged ventilator support (p <0.05), more likely to have acute renal failure (p<0.0001), more transfusions and re-operation for bleeding (p<0.05), higher death rate (5.7% versus 2.6%; p<0.01) and longer length of hospital stay (11.4 versus 8.3 days; p<0.00001). In multivariate analyses evaluating factors related to death, emergent surgery, poor ejection fraction and older patient age were independently related to mortality. Small body surface area was not an independent predictor. The results of this study indicate that smaller patients do have poorer outcomes associated with coronary artery bypass surgery. However, 90% of the smaller patients did have an event-free surgery. Surgeons may need to monitor these patients more closely and anticipate the increased risk and cost that is associated with this group.

Adult↗
PubMed2000

Declawing of neonatal rabbits destined for use in animal biosafety level 4 containment studies.

To protect personnel and protective outerwear from damage by scratching, rabbits to be housed in an Animal Biosafety Level 4 (ABSL4) facility are declawed routinely. The objective of the study presented here was to establish a procedure for declawing all four feet of neonatal rabbits in preparation for use in ABSL4 studies. Combining procedures conducted in private veterinary practice to remove dewclaws of canine pups with those used to declaw cats, we declawed rabbit kits at 3 to 8 days of age. Declawing neonates was believed to be advantageous because they are non-ambulatory, have soft, cartilaginous digits, and do not have extensive hair growth. These features resulted in decreased surgical preparation and surgery time, minimal bleeding, and minimal aftercare. The optimal age for declawing a litter was 6 or 7 days. Declawing of neonatal rabbits is relatively simple and efficient to perform and offers advantages over declawing of older animals. By using the method described, rabbits can be introduced into ABSL4 facilities by 12 weeks of age with confidence that nail regrowth will not occur.

Animals↗
PubMed1999

Recent improvement in results of coronary bypass surgery in octogenarians.

BACKGROUND: Because of concerns regarding the cost-effectiveness of coronary artery surgery in patients 80 years and older, a review of a large experience is appropriate. METHODS: The records of 404 consecutive patients 80 years of age or older having isolated coronary bypass surgery (CABG) from 1985 through 1996 were reviewed. Patients were divided equally into an early and later group. Hospital mortality, complications including major arrhythmias, wound infections and separations, re-explorations, peri-operative Q-wave myocardial infarctions, major organ dysfunction, stroke, time to extubation, post-operative hospital (LOS) and intensive care unit (ICU) lengths of stay were compared. A logistic regression risk model was used to assess the relative contributions of improved technique versus more favorable patient selection. RESULTS: Comparison of the two groups revealed the following: overall hospital mortality decreased from 12.9% to 5.4% (p = 0.003), more markedly so with elective procedures where hospital mortality decreased from 8.1% to 1.2% (p = 0.04). There were significant decreases in time to extubation (2.8 +/- 9.3 days versus 1.2 +/- 2.8 days; p = 0.02), post-operative intensive care unit stay (4.9 +/- 7.1 days versus 2.9 +/- 3.7 days; p = 0.0004), post-operative complication rate (34.2% versus 22.8%; p = 0.03), and post-operative hospital length of stay (14.2 +/- 14.7 days versus 9.8 +/- 9.8 days; p = 0.0005). Post-operative stroke decreased from 7.4% to 5.9%. Mean estimated risk for the two groups was 8.2 +/- 10.2% versus 8.2 +/- 11.4%. CONCLUSION: Coronary surgery can be performed with acceptable risk in octogenarians. Results have improved over the past few years. This improvement is probably not attributable to patient selection.

Aged↗
PubMed1997

Intrinsic and required dynamics of a simple bat-ball skill.

Three experiments investigated the coordination dynamics of a simple bat-and-ball skill: cyclically striking a ball suspended by a string with a pendular bat. The relative phase phi between the bat and ball is dictated by the potential function V(phi) = k sin phi and the difference delta omega in their uncoupled frequencies. For various delta omega, phi and its standard deviation were measured in the absence of any environmental restraints (intrinsic dynamics) and when the ball had to reach resistive or nonresistive targets at set distances (required dynamics). Results support the dynamical theory of coordination patterns (G. Schöner & J.A.S. Kelso, 1988a, 1988c), particularly the hypothesis that required dynamics are understandable as the addition of terms to the potential governing the intrinsic dynamics.

Biomechanical Phenomena↗
PubMed1997

Making the constraints visible: testing the ecological approach to interface design.

A haemodynamic monitoring and control task was used to evaluate the ecological approach to interface design for complex high-technology environments. Guidelines proposed by Bennett and Flach (1992) were used to design multilevel displays that made visible (a) anatomical constraints, and (b) causal constraints on haemodynamic systems. These displays were compared with a traditional display that showed pressure and flow values in five separate graphs. Simulations of clinical problems were generated by a computer model and presented in an interactive computer environment. Critical care nurses and nursing students observed changes in pressures and flow corresponding to certain disease states and corrected those states using simulated drugs. For both groups, speed and accuracy were progressively improved by the enhanced, multilevel displays.

Computer Simulation↗
PubMed1996

Outcome of narrowing related side branches after high-speed rotational atherectomy.

High-speed rotational atherectomy (HSRA) is advocated for calcified and diffusely narrowed coronary arteries. There are often side branches involving these kinds of lesions. The presence of significant lesion-related side branches has been considered a relative contraindication to rotational atherectomy. This study was performed to determine the rate, predictors, and outcome of side branch occlusion after HSRA. The angiograms of 418 patients were examined with 320 side branches in 240 target vessels of > or = 1 mm in diameter being identified. Vessels were scored as either perfused (Thrombolysis In Myocardial Infarction 2 or 3 flow) or occluded (Thrombolysis In Myocardial Infarction 0 or 1 flow before and after the procedure. A detailed quantitative angiographic analysis was performed on a total of 108 side branches including all cases of branch occlusion. Clinical outcomes were determined in all cases with side branch loss. There were 24 occlusions in 21 patients after the procedure, giving a rate of branch loss of 7.5%. Follow-up angiography of > or = 24 hours was available for 13 of the occluded branches and 12 were found to be patent. In the 21 patients with branch occlusion, 6 sustained a myocardial infarct (of which 5 were non-Q-wave), 2 underwent coronary artery bypass grafting, and 2 died. There are frequently lesion-associated side branches in the types of vessels to undergo HSRA. These branches remained patent 92.5% of the time, with occlusion occurring infrequently and usually being transient. When occlusion did occur, there was a 29% incidence of myocardial infarction.

Aged↗
PubMed1996

High-speed rotational atherectomy: six-month serial quantitative coronary angiographic follow-up.

One hundred twenty-three patients treated with high-speed rotational atherectomy (HSRA) were restudied 6.9 +/- 1.2 months later. At the follow-up, the number of focal concentric lesions increased from 32.2 percent to 63.0 percent, p<0.01, with decrease of type C lesions from 54.8 percent to 30.8 percent, p<0.05. Comparison of the degree of the net gain (NG) showed more severe baseline lesions in the high-gain group (NG >20 percent) compared with the moderate-gain group (20 percent > NG > 0 percent) and to the loss group (minimal luminal diameter [MLD] 0.8 +/- 0.4 mm vs 1.0 +/ 0.4 mm, p<0.05; and 1.2 +/- 0.5 mm; p<0.01, respectively). Highest initial gain (36.5 percent +/- 26.2 percent vs 24.5 percent +/- 18.1 percent; p<0.015; and 19.0 percent +/- 23.2 percent; p<0.001) as well as lowest late loss (1.8 percent +/- 21.7 percent vs 14.0 percent +/-18.4 percent; p<0.01 and 28.1 percent +/- 25.0 percent; p<0.01) were found in the high NG group. A higher interaction between burr and atheroma resulted in the lowest restenosis rate of 6 percent.

Aged↗
PubMed1995

Role of intraaortic balloon pump counterpulsation in high risk coronary rotational atherectomy.

OBJECTIVES: This study sought to evaluate the role of intraaortic balloon pump counterpulsation in preventing hemodynamic instability and promoting a successful outcome during percutaneous transluminal coronary rotational atherectomy in high risk patients. BACKGROUND: The application of rotational atherectomy has widened to include patients with complex lesions and left ventricular dysfunction. Although intraaortic balloon pumping has been successfully used to provide hemodynamic support during balloon angioplasty, its role in high risk rotational atherectomy has not yet been defined. METHODS: In a retrospective review of 159 consecutive high risk patients who underwent rotational atherectomy, 28 had an intraaortic balloon pump placed electively before the procedure (Group 1) whereas 131 did not (Group 2). RESULTS: Group 1 was older and more likely to have multivessel disease and left ventricular dysfunction. Augmented diastolic pressure was maintained > 90 mm Hg in all Group 1 patients, and significant procedure-related hypotension was encountered in nine Group 2 patients, requiring an emergency intraaortic balloon pump in five. Procedural success was achieved in all 28 patients in Group 1 and in 118 in Group 2 (p = 0.07). Slow flow occurred in 18% and 17% of Group 1 and 2 patients, respectively. Among patients with slow flow, non-Q wave myocardial infarction occurred only in Group 2 (0% vs. 27%). On multivariate analysis, elective intraaortic balloon pump placement was the only variable to correlate with a successful procedure uncomplicated by hypotension (p < 0.05). Hospital stay and vascular complications were similar in both groups. CONCLUSIONS: Elective placement of an intraaortic balloon pump before coronary rotational atherectomy in selected high risk patients promotes both procedural hemodynamic stability and a successful outcome.

Aged↗
PubMed1995

Effects of technique modification on immediate results of high speed rotational atherectomy in 710 procedures on 656 patients.

Seven hundred ten high speed rotational atherectomy (HSRA) procedures were performed in a single consecutive series of 656 patients. Stand alone HSRA was performed in 253 patients (35%). HSRA with adjunctive low pressure (< or = 2 ATM) balloon angioplasty (LP BA) was performed in 221 patients (31%), and HSRA with adjunctive high pressure (> or = 4 ATM) balloon angioplasty (HP BA) was performed in 236 patients (34%). Prognostically unfavorable Type B2 and C lesions dominated the study group (74.7%). Procedural success rate was 96%. Emergency coronary artery bypass surgery was performed in 1.4% of cases, Q wave myocardial infarction occurred in 3.4% and death, related to procedure, was consequent in 0.5% of cases. Incidence of flow limiting dissections was 3.1%, distal spasm was 5.3%, and "no reflow" phenomenon was 1.8%. The recent technique modifications included continuous advancer/guiding catheter infusion of the nitroglycerin-verapamil mixture, limitation of duration of lesion engagement by the burr, stepwise increase in the burr size, decrease of rotational speed, and strict control of rpm drop during lesion ablation. Evolution of the interventional technique involved trends towards decrease of the use of HP BA in conjunction with steady increase in the percentage of SA and LP BA procedures over time. These technique changes resulted in complete absence of "no reflow" in 1994, as well as a generalized decrease in overall coronary vascular reactivity from all burr passes.

Adult↗
PubMed1995

Arterial conduits in emergency coronary artery surgery.

The internal thoracic artery (ITA) is considered to be the conduit of choice for coronary bypass (CABG), but there has been some reluctance to utilize the ITA for revascularization in emergency situations. In a 9-year retrospective analysis from 1986 through 1993, 484 patients had emergency CABG, 237 were not associated with failed PTCA (noninstrumented) and 247 were within 24 hours of PTCA (instrumented). About 62% of noninstrumented and 49.3% of instrumented patients received one or more ITA grafts, the others receiving only saphenous vein grafts (SVGs). Those who received an ITA graft tended toward male sex, better ejection fraction, and a generally lower clinical risk score. Instrumented patients tended toward a lower incidence of diabetes and left main coronary disease, higher ejection fraction, and lower clinical risk score than noninstrumented patients. The postoperative results were not significantly different between ITA and SVG groups with respect to new Q waves, need for reexploration, sternal wound infection, respiratory complications, or stroke. However, ITA patients more often had an event-free postoperative course, received fewer blood transfusions, and experienced fewer cardiac deaths (2.7% vs 9.4%, p < 0.01). There were few obvious differences in postoperative results between instrumented and noninstrumented patients. These results indicate that the ITA can be used for emergency CABG in selected patients with good results.

Aged↗
PubMed1995

Dyslipoproteinemias in atherosclerosis, thrombosis and restenosis after coronary angioplasty.

Lipids play a vital role in normal metabolic function in mammals. However, dyslipoproteinemias have been implicated in the pathophysiologic process of atherogenesis, thrombogenesis and restenosis after interventional procedures. Lipoproteins provide important chemical linkages among these three complex phenomena. Lipoproteins participate in atherogenesis and play a major role in plaque fissuring, the pathophysiologic common denominator of acute ischemic syndromes. Thrombogenesis is majoraly affected by the action of lipids on platelets, coagulation and fibrinolysis. LDL tend to destabilize platelet membrane activity, macrophages, endothelial and smooth muscle cell function; HDL tend to reverse these abnormalities. The metabolism of arachidonic acid, a metabolite of the essential polyunsaturated lipoprotein, linoleic acid, is integral to platelet and endothelial cell membrane formation, via the cyclooxygenase-prostanoid pathway. Arachidonic acid also is metabolized by the lipoxygenase-leukotreine pathway in neutrophils and monocytes. The relationship of dyslipoproteinemias (increased LDL and Lp(a); decreased HDL) to restenosis after angioplasty has been reported, though there is not universal agreement about causality. Lipid lowering regimens and other pharmacotherapy have had favorable effect slowing the rate of atherogenesis, decreasing the frequency of cardiac events (perhaps by "stabilizing" vulnerable plaques) and causing regression in some atheromata. The salutary effect of lipid-lowering agents upon the incidence of restenosis after angioplasty is problematic. Some investigators have found a statistically significant correlation, while others have not; but studies have not been standardized. In conclusion, the study of lipid metabolism across a wide range of physiochemical activities and the interaction of these phenomena describe complex, genetically determined linkages which instruct (and often humble) investigators in their study of lipids in health and disease.

Angioplasty↗