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Biomedical subjects

J J Ferguson

Publications and source records attributed to J J Ferguson.

At least 73 records · Page 4Linked to original sources
PubMed1996

PTCA in angulated segments: effects of balloon material, balloon length, and inflation sequence on straightening forces in an in vitro model.

We sought to determine the effect of balloon material, balloon length, and inflation sequence on the straightening forces generated during percutaneous transluminal coronary angioplasty (PTCA) in angulated segments. Using an in vitro model consisting of a curved channel (3/4" radius) with a displaceable pressure sensor, we examined four different balloon materials: compliant (POC), semicompliant (PE600 and Duralyn), and noncompliant (PET), two balloon lengths (20 mm and 40 mm), and two inflation sequences (rapid and slow) with continuous recording of straightening force during each balloon inflation. Three balloons were tested for each combination of materials, length, and inflation sequence. Long balloons exerted significantly lower straightening forces. There were significantly higher straightening forces with noncompliant, particularly short, balloons. Varying the inflation sequence had no significant effect. For PTCA in angulated segments: (1) long balloons produce lower straightening force, (2) noncompliant balloons produce higher straightening force, particularly with short balloons, and (3) varying the inflation sequence has no significant effect on straightening force.

Angioplasty, Balloon, Coronary↗
PubMed1996

Localized administration of sodium nitroprusside enhances its protection against platelet aggregation in stenosed and injured coronary arteries.

Sodium nitroprusside, a potent vasodilator, was evaluated for its effect on platelet aggregation in stenosed and endothelium-injured coronary arteries in a canine model. Twenty-five anesthetized dogs were studied; coronary blood flow velocity was continuously monitored. Recurrent intracoronary platelet aggregation and dislodgment (indicated by cyclic variations in coronary blood flow) were induced by mechanically injuring and stenosing the left anterior descending coronary artery. Sodium nitroprusside was administered either intrapericardially or intravenously 30 min after cyclic flow variations were established. Intrapericardial administration of saline (control) did not affect cyclic flow variations in any of 6 tested dogs. Sodium nitroprusside abolished cyclic flow variations in all 7 dogs (100%) when given intrapericardially and in 5 to 7 dogs (71%) when given intravenously (compared to intrapericardial salines, p < 0.01). A smaller dose of sodium nitroprusside was required to abolish cyclic flow variations when given intrapericardially than when given intravenously (1.6 +/- 0.5 micrograms.kg-1.min-1 vs 4.8 +/- 0.8 micrograms.kg-1.min-1, p < 0.01). The mean aortic pressure was reduced by 10 to 20 mmHg after intrapericardial sodium nitroprusside administration and by 30 to 40 mmHg after intravenous sodium nitroprusside administration. To investigate the mechanism of protection by sodium nitroprusside, NG-monomethyl-L-arginine, an inhibitor of nitric oxide synthetase, was used to induce cyclic flow variations in mildly injured and stenosed left anterior descending coronary arteries in 5 dogs. Intrapericardial sodium nitroprusside abolished the cyclic flow variations in all 5 dogs. Then oxyhemoglobin, an inhibitor of nitric oxide, was administered into the left anterior descending coronary arteries of these dogs, and it restored the sodium nitroprusside-abolished cyclic flow variations in all 5 dogs. Thus, sodium nitroprusside protects against platelet aggregation and cyclic flow variations in stenosed and endothelium-injured canine coronary arteries, probably by the action of nitric oxide, and it is more effective and hemodynamically safer when administered intrapericardially than when administered intravenously.

Administration, Topical↗
PubMed1996

High-risk coronary angioplasty assisted by active hemoperfusion. A feasibility study.

We assessed the effectiveness of distal hemoperfusion support during gradual, prolonged balloon inflation during percutaneous transluminal coronary angioplasty in high-risk patients. The patients were identified as having a poor left ventricular ejection fraction ( < 35%), > 50% of viable myocardium at risk percutaneous coronary balloon angioplasty, or both. A total of 64 procedures were performed in 61 patients. Angiographic success was achieved in 83 of 86 (96.5%) lesions treated with hemoperfusion support. Hospital complications included 1 patient who had a non-Q-wave infarction, 1 who had to undergo redo percutaneous coronary balloon angioplasty, and 5 who required coronary artery bypass operations. The hospital mortality was 7.8% (5 patients). This preliminary study indicates that hemoperfusion support can enable expeditious, simple, economical, and effective percutaneous transluminal coronary balloon angioplasty in a subset of labile patients in whom procedural failure frequently leads to sudden death.

Angioplasty, Balloon, Coronary↗
PubMed1995

Length of hospital stay and complications after percutaneous transluminal coronary angioplasty. Clinical and procedural predictors. Heparin Registry Investigators.

BACKGROUND: Although several studies have established that the complications of percutaneous transluminal coronary angioplasty (PTCA) are related to clinical and angiographic variables such as advanced age and lesion complexity, it is uncertain whether the use of hospital resources after PTCA also depends on the same baseline variables. The purpose of this study was to identify the factors responsible for prolonged hospital stay after PTCA. METHODS AND RESULTS: The study cohort included 591 consecutive patients undergoing conventional balloon angioplasty at nine medical centers in North America. Major or minor complications occurred in 91 patients (15.4%) and were observed to be related to several baseline characteristics, including unstable angina, multivessel coronary artery disease, patient age, and lesion complexity. Compared with a median length of hospital stay of 2.0 days after PTCA (25th, 75th percentiles: 2.0, 4.0) for the entire cohort of patients, the length of stay was increased in patients with unstable angina (3.0 days [2.0, 5.0]; P = .002), multivessel coronary artery disease (3.0 [2.0, 5.5]; P = .001), age > 65 years (3.0 [2.0, 5.5]; P = .02), complex lesions (3.0 [2.0, 6.0]; P = .001), and filling defects (6.0 [2.0, 11.0]; P < .001). The length of stay was more strikingly increased, however, in patients who experienced major or minor PTCA complications, such as emergency bypass surgery (9.0 days [8.0, 18.0]; P < .001), Q-wave or non-Q-wave myocardial infarction (8.0 [6.0, 15.5]; P < .001), transfusion unrelated to bypass surgery (8.0 [4.0, 12.0]; P < .001), or abrupt vessel closure (6.0 [3.0, 10.5]; P < .001). On stepwise multiple linear regression, PTCA complications appeared to be the strongest predictors of length of hospital stay (all P < .001) and overwhelmed the weaker relation between length of stay and several individual baseline variables. Inclusion of a composite clinical risk score (reflecting the presence of unstable angina, multivessel disease, advanced age, complex lesions, or filling defects) in the regression model confirmed that patients with several high-risk baseline variables had a significant increase in length of stay after PTCA (P = .003), but PTCA complications remained the strongest predictors of length of stay. CONCLUSIONS: Although PTCA complications were correlated with baseline variables such as unstable angina, multivessel disease, advanced age, complex lesions, and filling defects, excess length of stay after PTCA was most strongly influenced by the development of minor and major PTCA complications. Because patients with several baseline risk factors experienced significantly prolonged hospitalizations, improved selection of patients may contribute to reductions in length of stay after PTCA. A greater reduction in resource use after PTCA, however, would be expected from developing new treatments to decrease PTCA complications rather than limiting the access of patients with unstable angina, advanced age, or complex lesions to PTCA.

Aged↗
PubMed1995

Meeting highlights.

Explore the source record for details and available documents.

American Heart Association↗
PubMed1995

Bleeding complications with the chimeric antibody to platelet glycoprotein IIb/IIIa integrin in patients undergoing percutaneous coronary intervention. EPIC Investigators.

BACKGROUND: The potential for novel antiplatelet and antithrombin agents to contribute to periprocedural bleeding complications of percutaneous coronary revascularization is poorly defined. In the Evaluation of c7E3 Fab in Preventing Ischemic Complications of High-Risk Angioplasty (EPIC) trial, the periprocedural use of aspirin, heparin, and a chimeric antibody to the platelet glycoprotein IIb/IIIa integrin c7E3 Fab in 2099 patients significantly reduced postprocedural ischemic complications and 6-month clinical restenosis but was associated with increased procedural bleeding complications. We review these complications and describe clinical and procedural variables associated with increased bleeding complications in the EPIC trial. METHODS AND RESULTS: Patients with high-risk clinical or lesion morphological characteristics were randomized to receive placebo bolus plus placebo infusion, c7E3 Fab bolus plus placebo infusion, or c7E3 Fab bolus plus c7E3 Fab infusion. Patients received periprocedural aspirin and intravenous heparin continued for a minimum of 12 hours after the procedure. Outcomes reflecting bleeding complications were measured: transfusions, decreased hemoglobin, and an index including both parameters. Major bleeding complications unrelated to bypass surgery occurred in 3.3%, 8.6%, and 10.6%, and blood product transfusions were used in 7.5%, 14.0%, and 16.8% of patients treated with placebo, bolus c7E3 Fab, and bolus plus infusion c7E3 Fab, respectively (both P < .001). Most major bleeding complications occurred at the femoral access site, regardless of treatment. Intracranial hemorrhage (0.3%) and death (0.09%) attributable to major bleeding complications were rare. Multivariable regression analyses identified several variables significantly and independently related to major bleeding complications or greater blood loss, including greater age, female sex, lower weight, c7E3 Fab therapy, and duration and complexity of the index procedure. Major bleeding complications and blood loss in patients receiving bolus plus infusion were not significantly greater than in those receiving bolus alone (P = .38 and P = .14, respectively). CONCLUSIONS: Bleeding complications unrelated to bypass surgery were two to three times more frequent in patients receiving c7E3 Fab than in those receiving placebo, but most were transient and well tolerated. Risk-factor analysis and modification of concomitant antithrombotic and antiplatelet treatment strategies may aid in reducing bleeding complications and enhancing clinical benefit in patients receiving c7E3 Fab during percutaneous coronary revascularization.

Aged↗
PubMed1995

Activated clotting times in acute coronary syndromes and percutaneous transluminal coronary angioplasty.

A discrete fall in the ACT (activated coagulation time) has been observed in patients with known activation of the coagulation cascade. Injury to the coronary artery resulting in thrombin activation, whether spontaneous as in the case of acute myocardial infarction or planned as with percutaneous transluminal coronary angioplasty (PTCA), may therefore be reflected in a change in ACT values. We reviewed the records of patients undergoing PTCA at St. Luke's Episcopal Hospital/Texas Heart Institute from January 1990 through December 1992 for information regarding ACT values and clinical events. A total of 469 patients, whose record contained adequate information for study inclusion, were divided into four separate groups: acute myocardial infarction (group I, n = 62), unstable angina with heparin therapy that was withdrawn at least 4 hr prior to PTCA (group II, n = 102), unstable angina with heparin therapy continued until the time of PTCA (group III, n = 154), and stable angina undergoing elective PTCA (group IV, n = 151). Heparin was discontinued 12-15 hr after the procedure in all but group I where anticoagulation was often maintained up to 72 hr. ACT values were measured prior to the PTCA procedure (baseline), after the initial heparin bolus of 10,000 U (postheparin) and approximately 12-18 hr after the procedure (heparin withdrawal).(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗
PubMed1995

Conventional antithrombotic approaches.

Thrombus formation during percutaneous transluminal coronary angioplasty (PTCA) markedly increases the risk of abrupt closure, procedural failure, and major complications. Pretreatment with heparin may be beneficial in preventing procedural complications, although strategies for ensuring that patients have adequate anticoagulation have been the focus of considerable debate. Several studies have suggested a relationship between the development of PTCA complications and a low activated clotting time (ACT) or a low increase in ACT in response to heparin. Although there have been no prospective studies showing the superiority of any given threshold ACT over any other, current data support a recommendation that anticoagulation for patients undergoing PTCA be titrated to a HemoTec ACT of greater than 275 to 300 seconds or to a Hemochron ACT of greater than 350 to 400 seconds. Adjusting the heparin bolus dose according to body weight does not achieve a more predictable level of anticoagulation, although it may help avoid excessive anticoagulation in lighter-weight patients.

Angioplasty, Balloon, Coronary↗
PubMed1995

Results of a national survey on anticoagulation for PTCA.

In order to assess the current practice patterns in the United States for anticoagulation during PTCA, a survey was sent to the ACC membership. A total of 377 surveys from physicians performing PTCA were tabulated; 5 (1.3%) respondents performed < 20 PTCAs/year, 128 (34.0%) performed 20-75 PTCAs/year, 141 (37.4%) performed 75-150 PTCAs/year, 98 (26.0%) performed > 150 PTCAs/year and 5 (1.3%) did not report their volume. Seventy-eight (20.7%) were at university hospitals 153 (40.6%) were at other teaching hospitals, 142 (37.7%) were at non-teaching hospitals and 4 (1.1%) did not report their institutional affiliation. A total of 76.8% of respondents routinely started with a 10,000 U bolus of heparin, while only 3.2% of respondents used only a weight-adjusted heparin bolus. Fifty-nine percent of respondents routinely used intra-procedure heparin infusions, usually 1000 U/hr. Anticoagulation monitoring was used by 92.6% of respondents during PTCA, almost always activated clotting times (ACTs). Of the 335 physicians who used ACTs to guide heparin therapy during PTCA, 59.1% used the Hemochron device, 16.7% used the HemoTec device, and 24.2% did not know which machine they used. Lower volume operators and operators at non-teaching hospitals were more likely not to know the type of ACT machine used. Post-procedure heparin infusions (usually titrated to an aPTT > 2 x control) were used by 70.3% of respondents. Lower volume operators were more likely to use post-procedure heparin infusions. Thus, heparin therapy for PTCA continues to be largely empiric, although the vast majority of cardiologists surveyed use ACT-guided heparin therapy for the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1995

Revascularization therapy for coronary artery disease. Coronary artery bypass grafting versus percutaneous transluminal coronary angioplasty.

Coronary artery bypass surgery relieves the symptoms of myocardial ischemia and prolongs survival of patients with more severe coronary artery disease. Randomized trials of surgical therapy have consistently shown that the benefits of surgical revascularization are proportional to the amount of myocardium affected by, or at risk for, ischemic injury. This risk is inferred from angiographically delineated coronary anatomy, estimates of left ventricular function, and physiologic testing. The population that may see a survival benefit from surgical revascularization has probably been expanded beyond that reported in the VA, CASS, and ECSS trials, due to improved perioperative care, longer graft survival, and the use of internal mammary artery grafts. Percutaneous transluminal coronary angioplasty revascularizes myocardium by dilating a stenotic segment of coronary artery. While successful in relieving the symptoms of myocardial ischemia, PTCA is hindered by the occurrence of abrupt vessel closure and the frequent development of restenosis. Furthermore, firm proof of a survival benefit, outside of emergency therapy for acute myocardial infarction, is not yet available. However, because the risk of procedure-related death or serious complication is lower than that seen with bypass surgery, PTCA provides a useful alternative revascularization method for patients with less extensive disease, in whom the risk of surgery may equal or exceed any beneficial effect. New technology and growing experience are widening the scope of percutaneous revascularization by extending the hope of symptomatic relief and survival benefit even to patients with extensive, severe coronary artery disease. Comparisons between surgical therapy and PTCA in select populations with single- and multivessel coronary artery disease have shown that PTCA is not as effective as surgery for long-term symptomatic control, and that it often requires repeat PTCA or cross-over to bypass surgery; however, long-term outcomes (i.e., death and myocardial infarction) are similar. The cost of treatment beginning with PTCA may be lower than that of initial surgery, even when the increased need for repeat revascularization is taken into account. Despite this, surgical bypass remains the mainstay of therapy for patients with severe coronary artery disease and a poor prognosis for survival, and will remain the fallback procedure for patients who repeatedly undergo failed PTCA. At the present time, revascularization should be offered on the basis of symptom severity (in the presence of medical therapy) and in accordance with the prognosis for survival as judged by the extent and severity of disease (Table VI). Percutaneous transluminal coronary angioplasty is preferred in patients who require revascularization but can obtain no proven benefit from bypass surgery. Coronary artery bypass surgery, using the internal mammary artery when possible, remains the revascularization method of choice for patients with more severe disease or whose disease is not amenable to treatment using percutaneous methods (Table VII).

Angioplasty, Balloon, Coronary↗