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Biomedical subjects

G W Stone

Publications and source records attributed to G W Stone.

83 records · Page 5Linked to original sources
PubMed1990

Procedural outcome of angioplasty for total coronary artery occlusion: an analysis of 971 lesions in 905 patients.

This study analyzes the results of angioplasty in 905 consecutive patients with 971 total occlusions. The procedures were performed by five cardiologists from January 1980 to January 1989 at one institution. The overall success rate per lesion was 72%. Even the most experienced operator (524 occlusions attempted) has continued to improve on a learning curve, with 83% of his most recent 100 occlusions successfully dilated. Procedural death occurred in seven patients (0.8%), five patients (0.6%) sustained a myocardial infarction and seven patients (0.8%) required urgent coronary bypass surgery. Complications were significantly more likely to occur in the elderly, in women and in patients with triple vessel disease and depressed left ventricular function. Compared with angioplasty in 6,950 patients with nonoccluded stenoses, angioplasty of total occlusions had a lower success rate (72% versus 96%, p = 0.001), although the complication rate was also lower (1.9% versus 3.5%, p = 0.01). Multivariate analysis of 20 clinical and angiographic variables in 100 consecutive patients undergoing angioplasty of 104 total occlusions in 1988 identified only bridging collateral vessels (85% success rate if absent versus 18% if present, p less than 0.001) and a tapered occlusion morphology (88% success rate if present versus 59% if absent, p = 0.01) as independent correlates of procedural outcome. Other variables, including the estimated duration of occlusion, lesion length and location, and extent of disease were unrelated to technical success. With present techniques and sufficient operator experience, 70% to 80% of total occlusions can be successfully recanalized by coronary angioplasty with a complication rate of less than 2%.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1990

Direct coronary angioplasty in acute myocardial infarction: outcome in patients with single vessel disease.

Percutaneous transluminal coronary angioplasty was performed as primary therapy in 215 consecutive patients (aged 56 +/- 11 years, 75% male) with acute myocardial infarction and single vessel coronary artery disease. Wide patency of the infarct-related artery was restored in 212 patients (99%). Complications consisted of one urgent coronary bypass operation (0.5%); there were no procedural deaths. A recurrent ischemic event before discharge occurred in eight patients (4%). The in-hospital mortality rate was 1%; five of six patients presenting with cardiogenic shock were alive at discharge. In 126 patients in whom predischarge angiography was performed, the ejection fraction improved from 55 +/- 12% to 61 +/- 12% (p less than 0.005) and increased by greater than or equal to 5% units in 66 patients (52%). Regional wall motion improved in 60 patients (48%). By multivariate analysis, a depressed initial ejection fraction, a limited increase in serum creatine kinase, young age and sustained patency of the infarct-related artery were found to be independent predictors of improvement in left ventricular function. Follow-up data were available in 214 patients (99.5%) at a mean interval of 35 months. The actuarial 3 year cardiac survival rate was 92%. By multivariate analysis, only the baseline ejection fraction correlated with long-term cardiac survival. Nine patients (4%) sustained a late nonfatal myocardial infarction, and 11 patients (5%) underwent subsequent coronary bypass surgery. At late follow-up study, 149 (77%) of 194 patients alive were free of angina. In summary, in patients with acute myocardial infarction and single vessel disease, coronary angioplasty without prior thrombolytic therapy can be performed with a high success rate and few procedural complications. After direct angioplasty, regional wall motion and global ejection fraction improve in 50% of patients, especially in those with depressed initial left ventricular function. This approach results in an excellent early and late event-free survival.

Adult↗
PubMed1989

Usefulness of percutaneous transluminal coronary angioplasty in alleviating silent myocardial ischemia in patients with absent or minimal painful myocardial ischemia.

To examine the role of percutaneous transluminal coronary angioplasty (PTCA) in patients with silent ischemia, 50 consecutive patients (mean age 54 years, 88% men) with 1-vessel disease and absent or minimal symptoms who underwent PTCA were identified. Nineteen patients (38%) were asymptomatic and 31 patients (62%) had minimal angina (at most 1 episode/month, and with marked exertion only). Exercise-induced ischemia was present in 45 of 49 patients (92%) tested. The remaining 5 patients had a critical stenosis in a vessel supplying a large myocardial territory. A total of 75 lesions were dilated, 71 successfully (95%). There were no procedural deaths or infarctions. The single complication was an urgent bypass operation. After PTCA, only 3 of 46 patients exercised (7%) had inducible ischemia (p less than 0.0005 vs before PTCA). At a mean follow-up of 36 months, 46 of 49 patients alive (94%) were asymptomatic (p less than 0.0005 vs before PTCA). The 3-year actuarial survival and infarct-free survival were 98 and 96%, respectively. However, 5 patients (10%) crossed over to bypass surgery and 14 patients (28%) underwent repeat PTCA. Progression of native coronary disease was present in 9 of these patients (47%). As in symptomatic patients, elective PTCA can be performed safely and with a high success rate in patients with silent ischemia, and can markedly reduce the incidence of exercise-induced ischemia. With this approach, greater than 90% of the patients were asymptomatic at the 3-year follow-up; however, 34% required a further revascularization procedure for restenosis or progression of native disease or both.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1989

A randomized trial of corticosteroids for the prevention of restenosis in 102 patients undergoing repeat coronary angioplasty.

To examine the effect of corticosteroid therapy on the development of restenosis following successful percutaneous transluminal coronary angioplasty (PTCA), we randomized 102 patients with restenosis following prior PTCA to receive high-dose steroids (n = 52) or no steroids (n = 50). The steroid regimen consisted of 125 mg methylprednisolone I.M. the night before and morning of the PTCA, and prednisone 60 mg p.o. Q.D. for 1 week. post-PTCA. Angiographic follow-up at 6 months was available in 27 steroid-treated patients (52%) and 27 controls (54%). The per lesion incidence of restenosis was similar in the two groups (36% vs. 40%, respectively, P = NS). Clinical follow-up was available in the remaining patients at a mean interval of 1.2 years. The clinical correlates of restenosis (incidence and severity of angina, positive treadmill exercise test, nonfatal infarction or death) were similar in the steroid treated and control groups (24% vs. 39%, respectively, P = .56). At late follow-up, 30 steroid-treated patients (58%) and 26 control patients (52%) had no clinical or angiographic evidence of restenosis (P = NS). In conclusion, a short course of high-dose corticosteroid therapy does not significantly reduce the frequency of restenosis following PTCA.

Angiography↗
PubMed1989

Short-term outcome and long-term follow-up following coronary angioplasty in the young patient: an 8-year experience.

From 8000 consecutive percutaneous transluminal coronary angioplasty (PTCA) procedures performed between 1980 and 1988, 89 separate PTCA procedures (1.1%) were performed in 71 patients less than or equal to 35 years of age. Multivessel disease was present in 41 patients (58%). Eleven procedures (12.4%) were done for acute myocardial infarction. Of 253 lesions attempted, 242 (95.6%) were successfully dilated. Complications consisted of just a single urgent bypass operation (1.1%). At mean follow-up of 32 months, 50 patients (72.5%) were asymptomatic. Late events consisted of one death (1.4%), four nonfatal infarctions (5.8%), and seven bypass surgeries (10.1%). Seventeen patients (24.6%) required 25 repeat PTCAs; restenosis was present in 12 of these patients while progression of native disease was noted in nine patients. In the young patient with coronary artery disease, PTCA can be performed safely, with a high success rate and few complications. Though the 3-year survival is excellent, a significant proportion of these patients develop nonfatal infarction or require repeat PTCA or bypass surgery, often for progression of native disease in addition to restenosis.

Adult↗
PubMed1986

Adverse influence of baroreceptor dysfunction on upright exercise in congestive heart failure.

To test the hypothesis that baroreceptor autoregulation is an important determinant of exercise performance, the hemodynamic responses to the gravitational stress of head-up tilt and upright exercise were assessed in 41 patients with severe chronic congestive heart failure. Three patterns of autonomic dysfunction during head-up tilt were identified. Group A patients had near-normal circulatory reflexes whereas Group B patients experienced orthostatic hypotension and Group C patients lacked the afferent stimulus of venous pooling. Group A patients had a significantly longer exercise duration than both Groups B and C (607 +/- 104 versus 330 +/- 86 and 365 +/- 53 seconds, respectively, p less than 0.05) and a significantly higher double product at peak exercise (17,779 +/- 956 versus 12,235 +/- 869 and 13,760 +/- 998, respectively, p less than 0.05). Thus, baroreceptor abnormalities in the autoregulatory response to postural change are important determinants of the cardiovascular responses required during exercise and influence exercise performance. These abnormalities may help clarify the discrepancies between supine and upright exercise performance and may influence the long-term efficacy of vasodilator therapy in chronic congestive heart failure.

Adult↗
PubMed1984

Preparation of alkylamine and 125I-radiolabeled derivatives of hyaluronic acid uniquely modified at the reducing end.

Present procedures to obtain radiolabeled hyaluronic acid derivatives are limited to low-specific-activity isotopes and small amounts of material, and often involve multiple points of chemical modification within the polymer. A synthesis has been developed which affords large quantities of a unique, chemically modified derivative of hyaluronic acid containing a single hydroxyphenyl group at the reducing end, which can be radioiodinated to high specific activity. Very little alteration in oligosaccharide structure is expected since only the terminal reducing sugar is modified. Oligosaccharides of hyaluronic acid, which have no free amino groups, were first converted to alkylamine derivatives to allow subsequent reaction with the Bolton-Hunter reagent, N-succinimidyl-3(4-hydroxyphenyl)propionate. Synthesis of the hyaluronate-amine was achieved by (i) reduction of the terminal reducing sugar with sodium borohydride, (ii) controlled sodium periodate oxidation to generate an aldehyde group only at the reduced end, and (iii) coupling this aldehyde to an alpha,omega- alkyldiamine (e.g., 1,6- hexanediamine ) in the presence of sodium cyanoborohydride. Purified hyaluronate-amine oligosaccharides were then reacted with the Bolton-Hunter reagent, and the hydroxyphenyl derivative thus obtained was radioiodinated with Na125I. Specific activities up to 8 X 10(9) cpm/nmol oligosaccharide can be obtained. This approach yields a uniquely modified, highly radioactive probe which will be useful in studies of cellular and extracellular matrix interactions with hyaluronic acid. In addition, the uniquely modified alkylamine derivative of hyaluronic acid has been used to prepare affinity chromatography media and synthetic cell culture surfaces.

Amines↗
PubMed1978

Oxygen requirement for prostaglandin biosynthesis.

The formation of prostaglandins by vesicular gland cyclooxygenase can be regulated by O2 concentrations below 30 micron (20 mm Hg) with an apparent Km value of about 5 micron. This result suggests that most mammalian tissues might be expected normally to have sufficient O2 for some synthesis, and that only occasionally, would the level of oxygen available within some tissues become marginally inadequate to sustain a high rate of prostaglandin biosynthesis.

Animals↗