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Biomedical subjects

S B King

Publications and source records attributed to S B King.

At least 19 recordsLinked to original sources
PubMed2001

Intracoronary beta-radiation exacerbates long-term neointima formation in balloon-injured pig coronary arteries.

BACKGROUND: Long-term biological effects of ionizing radiation on coronary arteries remain poorly defined. We examined late arterial responses 6 months after balloon angioplasty and beta-radiation in normal pig coronary arteries. METHODS AND RESULTS: Coronary arteries of 25 adult pigs were randomized to receive 20 Gy (n=8) or 30 Gy (n=9) of (186)Re beta-radiation or sham radiation (n=8) immediately after balloon angioplasty. Aspirin was given daily during follow-up. The study vessels were analyzed histopathologically at 6 months. beta-Radiation decreased lumen area (20 Gy, 1.55+/-0.99 mm(2); 30 Gy, 1.03+/-0.82 mm(2); and 0 Gy, 2.05+/-0.80 mm(2); P<0.05) but not overall vessel area. The neointimal area was significantly larger within the injured segment with beta-radiation (20 Gy, 1.92+/-1.23 mm(2); 30 Gy, 1.51+/-0.97 mm(2); and 0 Gy, 0.89+/-0.31 mm(2); 0 Gy versus 20 Gy, P<0.05), and a significant increase of edge stenosis was observed with beta-radiation. Irradiated vessels also had larger thrombus areas within the neointima (30 Gy, 0.24+/-0.61 mm(2); 20 Gy, 0.98+/-1.57 mm2; and 0 Gy, 0.00+/-0.01 mm(2); P<0.05) and larger adventitial areas (20 Gy, 2.25+/-0.75 mm(2); 30 Gy, 2.38+/-0.98 mm(2); and 0 Gy, 1.23+/-0.29 mm(2); 0 Gy versus 20 or 30 Gy, P<0.05) that showed substantial collagen accumulation. CONCLUSIONS: Intracoronary beta-radiation did not inhibit neointima formation in balloon-injured normal pig coronary arteries 6 months after the interventional procedure. Unresorbed thrombus contributed to, but was not the sole component of, augmented neointima formation. Irradiated vessels demonstrated more adventitial thickening and fibrosis. These observations may have relevance for long-term clinical outcomes after intracoronary beta-radiation.

Angioplasty, Balloon, Coronary↗
PubMed2001

High-dose external beam irradiation inhibits neointima formation in stented pig coronary arteries.

PURPOSE: To evaluate high-dose external beam irradiation (EBRT) in a pig coronary stent preparation because low and intermediate-dose EBRT failed to show inhibition of neointima formation in stented animal models. METHODS AND MATERIALS: Thirty-five stents were implanted in the coronary arteries of 17 pigs. Seven pigs were exposed to a single dose of 21 Gy EBRT immediately after stenting. Ten stented, nonirradiated pigs served as controls. After 4 weeks, the study arteries and myocardium were examined by light and scanning electron microscopy. RESULTS: Compared with controls, 21 Gy EBRT resulted in a larger lumen area (7.57 +/- 1.67 mm2 vs. 4.00 +/- 1.63 mm2, p <0.001), a smaller neointima area (0.47 +/- 0.43 mm2 vs. 3.36 +/- 2.26 mm2, p <0.001) and a smaller maximal intimal thickness (0.16 +/- 0.09 mm vs. 0.68 +/- 0.31 mm, p <0.001). Unresorbed intramural hemorrhages and adherent mural thrombi were present in the irradiated vessels, which also showed incomplete re-endothelialization. The irradiated hearts demonstrated diffuse interstitial and perivascular inflammation and fibrosis. CONCLUSIONS: EBRT at 21 Gy to the entire heart significantly inhibited neointima formation in stented pig coronary arteries but also resulted in incomplete re-endothelialization, myocardial inflammation, and fibrosis. Improvements in localization and delivery techniques are required to allow clinical implementation of this technique.

Animals↗
PubMed2001

Trends in outcome and costs of coronary intervention in the 1990s.

Our objective was to examine trends in outcome and cost of percutaneous coronary intervention (PCI) between 1990 and 1999. PCI has become the most common form of myocardial revascularization in recent years, rivaling the more established coronary artery bypass surgery. There has been increasing interest in improving outcome of PCI while also seeking to minimize cost. A total of 21,755 patients undergoing PCI were evaluated. Clinical data were gathered from the Emory Cardiovascular Database and financial data from the UB92 formulation of the hospital bill. Charges were reduced to cost using departmental cost-to-charge ratios. Costs were inflated to 1999 dollars using medical care inflation rates. Mortality varied without a significant trend from 0.63% to 0.44% (p = 0.64). The Q-wave myocardial infarction rate decreased from 0.68% to 0.40% (p = 0.0003). Emergent coronary surgery decreased from 3.50% to 1.25% (p <0.0001). Mean hospital inflation-adjusted cost decreased from $10,478 to $8,367 (p <0.0001). Length of stay after the procedure decreased from 2.8 to 1.8 days (p <0.0001). Outcome of PCI continues to improve, with a decrease in coronary surgery and Q-wave myocardial infarction but with no significant change in mortality. This was accomplished while also decreasing costs and length of stay. Whether these favorable trends will continue remains to be seen.

Age Distribution↗
PubMed2001

Changes in the practice of percutaneous coronary intervention: a comparison of enrollment waves in the National Heart, Lung, and Blood Institute (NHLBI) Dynamic Registry.

The National Heart, Lung, and Blood Institute Dynamic Registry includes 15 clinical sites in wave 1, and 16 sites in wave 2 as well as a data-coordinating center. The first wave of enrollment began in July 1997 and was completed in February 1998. The second wave began in February 1999 and ended in June 1999. There were a total of 2,526 patients in wave 1 and 2,109 patients in wave 2. Comprehensive pre-, intra-, and postprocedure (in-hospital) data were analyzed for changes between recruitment waves. Patients in wave 2 were more frequently nonwhite (p < or = 0.001), hypertensive by history (p < or = 0.001), had more significant noncardiac comorbidity (p < or = 0.01), and had more frequently undergone prior percutaneous coronary intervention (p < 0.05). Patients in wave 2 underwent percutaneous coronary intervention in a setting of acute coronary syndromes more frequently than wave 1 patients (p < or = 0.001). However, most interventions in both waves were performed on 1 vessel, irrespective of the extent of disease. Attempted lesions in wave 2 were longer (p < or = 0.001), less frequently totally occluded (p < or = 0.001), and more frequently in vessels with a prior stent (p < or = 0.01). Using the American Heart Association/American College of Cardiology lesion classification scheme, attempted lesions in wave 2 were less complex than those in wave 1 (p < or = 0.001). Stent use increased significantly from wave 1 (67%) to wave 2 (79%, p < or = 0.001) as did the use of platelet glycoprotein IIb/IIIa antagonists (wave 1, 24%; wave 2, 32%: p < 0.001). Procedural outcomes (angiographic success without major in-hospital adverse events) were excellent in both waves 1 (94.6%) and 2 (95.6%) and were not significantly different. However, the frequency of significant procedural coronary dissection and in- and out-of-laboratory abrupt closure were significantly less in wave 2 (p < or = 0.001) Discharge medications were more likely to include angiotensin-converting enzyme inhibitors, beta-adrenergic blocking agents, and hypolipidemic treatment in wave 2 than in wave 1 (p < or = 0.001). These data indicate a continuing aggressive approach to patient care over the time interval analyzed. Although overall procedural outcomes are excellent, procedural safety has been further enhanced. There is also a growing awareness of the importance of secondary prevention among interventional cardiologists.

Aged↗
PubMed2001

In vitro exposure to hydroxyurea reduces sickle red blood cell deformability.

Hydroxyurea is a drug that is used to treat some patients with sickle cell disease. We have measured the deformability of sickle erythrocytes incubated in hydroxyurea in vitro and found that hydroxyurea acts to decrease the deformability of these cells. The deformability of normal erythrocytes was not significantly affected by hydroxyurea except at very high concentrations. Hydroxyurea also did not consistently reduce the deformability of sickle erythrocyte ghosts. We propose that the decreased deformability, observed in vitro, is due to the formation of methemoglobin and other oxidative processes resulting from the reaction of hydroxyurea and oxyhemoglobin. Although the reaction with normal hemoglobin is similar to that of sickle hemoglobin, the sickle erythrocytes are affected more. We propose that the sickle erythrocyte membrane is more susceptible to the reaction products of the reaction of hemoglobin and hydroxyurea. An earlier report has shown that hydroxyurea increases the deformability of erythrocytes in patients on hydroxyurea. Taken together, these data suggest that the improved rheological properties of sickle erythrocytes in vivo are due to the elevated numbers of F cells [cells with fetal hemoglobin]. The presence of the nitrosyl hemoglobin or methemoglobin from the reaction with hydroxyurea may also benefit patients in vivo by reducing sickling.

Anemia, Sickle Cell↗
PubMed2000

Global impairment of coronary blood flow in the setting of acute coronary syndromes (a RESTORE substudy). Randomized Efficacy Study of Tirofiban for Outcomes and Restenosis.

Acute coronary syndromes result in a global impairment of coronary blood flow with nonculprit artery blood flow being associated with culprit artery flow and vice versa. Improvements in nonculprit artery flow are related to improvements in culprit artery flow after percutaneous intervention; nonculprit arteries with abnormal flow sustain greater improvements in their flow after culprit artery intervention.

Angina, Unstable↗
PubMed2000

P-Nitrosophosphate compounds: new N-O heterodienophiles and nitroxyl delivery agents.

P-Nitrosophosphates, such as 9, react as N-O heterodienophiles with 1,3-dienes to form highly functionalized cycloadducts that can be directly transformed into allylic phosphoramidates. The in situ periodate oxidation of the unstable N-hydroxyphosphoramidate precursors provides an efficient preparation of these new reactive intermediates. P-Nitrosophosphate (9) regioselectively reacts with 1-methoxy-1,3-butadiene to provide cycloadduct 16. P-Nitrosophosphate (9) also reacts with 9,10-dimethylanthracene to give cycloadduct 17, which undergoes retro Diels-Alder dissociation to re-form 9. In the absence of a 1,3-diene, the decomposition of 17 produces nitrous oxide, evidence for nitroxyl, the one-electron-reduced form of nitric oxide. An asymmetric P-nitrosophosphate reacted with 1,3-cyclohexadiene to form a mixture of diastereomeric cycloadducts (19 and 20) in a 1.6:1 ratio. These results identify P-nitrosophosphates as new species that react similarly to acyl nitroso compounds, making them useful synthetic intermediates and potential nitroxyl delivery agents.

Journal Article↗
PubMed2000

Percutaneous coronary intervention in the current era compared with 1985-1986: the National Heart, Lung, and Blood Institute Registries.

BACKGROUND: Although refinements have occurred in coronary angioplasty over the past decade, little is known about whether these changes have affected outcomes. METHODS AND RESULTS: Baseline features and in-hospital and 1-year outcomes of 1559 consecutive patients in the 1997-1998 Dynamic Registry who were having first coronary intervention were compared with 2431 patients in the 1985-1986 National Heart, Lung, and Blood Institute Registry. Compared with patients in the 1985-1986 Registry, Dynamic Registry patients were older (mean age, 62 versus 58 years; P:<0.001) and more often female (32.1% versus 25.5%; P:<0.001). In the Dynamic Registry, procedures were more often performed for acute myocardial infarction (22.9% versus 9.9%; P:<0.001) and treated lesions were more severe (84.5% versus 82.5% diameter reduction; P:<0.001), thrombotic (22.1% versus 11.3%; P:<0.001) or calcified (29.5% versus 10.8%; P:<0.001). Stents were used in 70.5% of Dynamic Registry patients, whereas 1985-1986 patients received balloon angioplasty alone. Procedural success was higher in the Dynamic Registry (92.0% versus 81.8%; P:<0.001) and the rate of in-hospital death, myocardial infarction, and emergency coronary bypass surgery combined was lower (4.9% versus 7.9%; P:=0.001) than in the 1985-1986 Registry. The 1-year rate for CABG was lower in the Dynamic Registry (6.9% versus 12.6%; P:<0.001). CONCLUSIONS: Although Dynamic Registry patients had more unstable and complex coronary disease than those in the 1985-1986 Registry, their rate of procedural success was higher whereas rates of complications and subsequent CABG were lower. Results of percutaneous coronary intervention have improved substantially over the past decade.

Angioplasty, Balloon, Coronary↗
PubMed2000

Costs of revascularization over eight years in the randomized and eligible patients in the Emory Angioplasty versus Surgery Trial (EAST).

The Emory Angioplasty versus Surgery Trial (EAST) was a randomized trial that compared, by intention to treat, the clinical outcome and costs of percutaneous transluminal coronary angioplasty (PTCA) and coronary bypass grafting (CABG) for multivessel coronary artery disease. We present the findings of the economic analysis of EAST through 8 years of follow-up and compare the cost and outcomes of patients randomized in EAST versus patients eligible but not randomized (registry patients). Charges were assessed from hospital UB82 and UB92 bills and professional charges from the Emory Clinic. Hospital charges were reduced to cost through step-down accounting methods. All costs and charges were inflated to 1997 dollars. Costs were assessed for initial hospitalization and for cumulative costs of the initial hospitalization and additional revascularization procedures up to 8 years. Total 8-year costs were $46,548 for CABG and $44,491 for PTCA (p = 0.37). Cost of CABG in the eligible registry group showed a pattern similar to that for randomized patients, but total cost of PTCA was lower for registry patients than for randomized patients. Thus, the primary procedural costs of CABG are more than those for PTCA; this cost advantage, given the limits of measurement, is largely or even completely lost for randomized patients over the course of 8 years because of additional procedures after a first revascularization by PTCA.

Angioplasty, Balloon, Coronary↗
PubMed2000

Outcome of coronary revascularization in patients on renal dialysis.

Previous retrospective studies showed high periprocedure mortality rate and poor outcome after percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG) among renal dialysis patients. The purpose of this study was to compare mortality and clinical event rates in renal dialysis patients after PTCA or CABG. We identified 252 patients from the Emory Cardiovascular Database who were on dialysis and who received PTCA (122 patients) or CABG (130 patients) at Emory University Hospital and Crawford W. Long Hospital between March 1987 and December 1997. Baseline and angiographic characteristics, in-hospital, and 1-year outcome were compared between the 2 groups. Left main disease and 3-vessel coronary artery disease were significantly more common in the CABG group. There was a higher periprocedure and in-hospital mortality in the CABG group (6.9% vs 1.6%, p = 0.04). Patients in the PTCA group underwent repeat revascularization 11 times more frequently within 1 year (22% vs 2%). At 1 year, mortality was 23% in the PTCA group and 27% in the CABG group, with no statistical difference between the 2 groups. This nonrandomized comparison reveals that PTCA and CABG can be performed in selected renal dialysis patients with an acceptable in-hospital major complication rate; however, 1-year mortality remains high in dialysis patients after coronary revascularization. Therefore, attempts at improving outcome in dialysis patients should focus on the prevention and treatment of coronary artery disease before they require coronary revascularization.

Aged↗
PubMed2000

The effect of endovascular irradiation on platelet recruitment at sites of balloon angioplasty in pig coronary arteries.

BACKGROUND: Endovascular irradiation (EI) inhibits balloon-induced neointima formation in animals and is now in clinical trials for restenosis prevention. However, little is known of the effect of EI on vessel thrombogenicity due to delayed arterial healing. We investigated EI effects on platelet recruitment in pig coronary arteries. METHODS AND RESULTS: EI was performed using (90)Sr/Y at 0 Gray (Gy), 15Gy, or 30Gy at 2 mm after balloon overstretch injury. At 1 day, 1 week, and 1 month, platelet recruitment and thrombus formation were assessed using autologous (111)In-oxine-platelet labeling and light and scanning electron microscopy. In balloon-injured nonirradiated vessels, there was complete reendothelialization at 1 month, and platelet recruitment was similar to normal uninjured arteries. In irradiated vessels, scanning electron microscopy showed incomplete reendothelialization at 1 month, and these areas demonstrated attachment of activated platelets. Light microscopy of irradiated coronaries showed adherent partially organized thrombi and incomplete resolution of intramural hemorrhages. There was a significant increase in platelet recruitment at 1 month in arteries receiving EI at 15Gy (5.1+/-2. 8x10(6), P=0.02) or 30Gy (12.5+/-9.9x10(6), P=0.005) compared with nonirradiated controls (2.7+/-1.5x10(6)); 30Gy was also higher than 15Gy (P=0.05). Platelet recruitment was also increased for 30Gy compared with control at 1 day. CONCLUSIONS: Endovascular irradiation at 15Gy or 30Gy after balloon angioplasty results in incomplete endothelial recovery, impaired resolution of intramural hemorrhage, and a dose-dependent increase in platelet recruitment at 1 month.

Angioplasty, Balloon, Coronary↗
PubMed2000

The reactions of myoglobin, normal adult hemoglobin, sickle cell hemoglobin and hemin with hydroxyurea.

The kinetics of the reaction of hydroxyurea (HU) with myoglobin (Mb), hemin, sickle cell hemoglobin (HbS), and normal adult hemoglobin (HbA) were determined using optical absorption spectroscopy as a function of time, wavelength, and temperature. Each reaction appeared to follow pseudo-first order kinetics. Electron paramagnetic resonance spectroscopy (EPR) experiments indicated that each reaction produced an FeNO product. Reactions of hemin and the ferric forms of HbA, HbS, and myoglobin with HU also formed the NO adduct. The formation of methemoglobin and nitric oxide-hemoglobin from these reactions may provide further insight into the mechanism of how HU benefits sickle cell patients.

Adult↗