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J J Ferguson

Publications and source records attributed to J J Ferguson.

At least 91 records · Page 5Linked to original sources
PubMed1995

Recent advances in the treatment of acute myocardial infarction.

A number of recent major clinical trials have added substantially to the understanding of what the current "optimal" therapy for acute myocardial infarction may include. This review highlights a number of studies that have been published or presented within the last 2 years. Clearly, there is still room for improvement, but we have made considerable progress in recent years, and the pace of our advances continues to accelerate.

Angioplasty, Balloon, Coronary↗
PubMed1994

Comparison of Hemochron and HemoTec activated coagulation time target values during percutaneous transluminal coronary angioplasty.

OBJECTIVES: The aim of this study was to determine whether activated coagulation time measurements from Hemochron and HemoTec machines can be used interchangeably and whether similar activated coagulation time target ranges for adequate anticoagulation can be applied to both machines. BACKGROUND: Adequate anticoagulation is necessary for the safe performance of intravascular interventions such as percutaneous transluminal coronary angioplasty. In current practice, anticoagulation status is frequently assessed by way of the activated coagulation time with one of two commercially available systems, HemoTec and Hemochron. Each one employs a different technique to determine the time of clot formation; however, the same target activated coagulation time values for adequate anticoagulation have been used interchangeably in published studies. METHODS: A total of 311 paired samples were compared in 113 high risk patients undergoing angioplasty enrolled in a randomized trial of a platelet glycoprotein IIb/IIIa receptor antibody. Simultaneous activated coagulation time measurements were obtained before and after administration of heparin, and the difference between the values of both machines was calculated. The relation between the Hemochron and HemoTec values was determined by using linear regression analysis. All activated coagulation time measurements were classified as either therapeutic or subtherapeutic using an arbitrary activated coagulation time target of 300 s. RESULTS: There was a correlation between values from the two machines (r = 0.86), but the Hemochron values were consistently higher than the HemoTec values by a mean value +/- SD of 28 +/- 29%, with wide individual variation. After heparin administration, there was a significant (p < 0.0001) difference between the number of measurements classified as therapeutic by HemoTec (53%) and by Hemochron (94%). CONCLUSIONS: HemoTec and Hemochron activated coagulation time measurements cannot be used interchangeably. Appropriate target activated coagulation time ranges to determine adequate anticoagulation during coronary angioplasty need to be established for both machines; the target range for one machine should not be extrapolated to the other.

Angioplasty, Balloon, Coronary↗
PubMed1994

The use of activated clotting times to monitor heparin therapy during and after interventional procedures.

Use of the activated clotting time (ACT) was recommended in the mid 1970s to guide administration and reversal of heparin during cardiopulmonary bypass. As the applications of cardiopulmonary bypass spread, so too did the need for more efficient techniques to assess coagulation status. This led to the development of automated ACT measurements. Today, the importance of coagulation and anticoagulation has been further highlighted by recent advances in the field of interventional cardiology. More and more cardiologists are using in-laboratory bedside coagulation monitoring to assess heparin requirements during interventional procedures such as percutaneous transluminal coronary angioplasty (PTCA). This review focuses on the development of anticoagulation monitoring and provides historic information on the clinical use of heparin. The application of ACTs in the catheterization laboratory and in other clinical situations is discussed, along with alternative methods for bedside assessment of coagulation status. No definite guidelines have been established for ACT monitoring during invasive intravascular procedures; thus its role continues to be refined. In the meantime, the ACT appears to be an extremely useful method for monitoring heparin therapy and the adequacy of anticoagulation.

Angioplasty, Balloon, Coronary↗
PubMed1994

Relation between procedural activated coagulation time and outcome after percutaneous transluminal coronary angioplasty.

OBJECTIVES: The purpose of this study was to determine whether a low procedural activated coagulation time is associated with a high rate of in-hospital complications and to identify whether there is an activated coagulation time range that may be associated with a low rate of complications. BACKGROUND: In recent years the activated coagulation time has come into widespread use for monitoring anticoagulation in the catheterization laboratory. However, considerable controversy exists as to the standards by which to judge "adequate" anticoagulation for interventional procedures. METHODS: From a total of 1,469 consecutive patients with percutaneous transluminal coronary angioplasty, we retrospectively identified 103 (Group I, 7% of the overall population) with major complications of death or emergency or urgent coronary artery bypass graft surgery and compared them with 400 patients without complications (Group II). Group I patients had more high risk clinical characteristics, such as type B and C lesions, class III and IV angina, recent myocardial infarction and recent thrombolytic treatment. Activated coagulation times were compared between Groups I and II at baseline, after administration of 10,000 U of heparin and at the end of the procedure. RESULTS: There were no differences in baseline activated coagulation times between Groups I and II. Group I had significantly lower activated coagulation times after heparin therapy and at the end of the procedure: 61% < 250 s, 20% between 250 and 275 s, 11% between 275 and 300 s and 8% > 300 s; 279 of Group II had activated coagulation times 27% < 250 s, 17% between 250 and 275 s, 35% between 275 and 300 s and 21% > 300 s (p < 0.0001). Complications occurred in all patients with final activated coagulation times < 250 s but in only 0.3% of patients with final activated coagulation times > 300 s. CONCLUSIONS: A diminished activated coagulation time response to an initial bolus of heparin is associated with major in-hospital complications after coronary angioplasty, although patients with complications did have a higher risk before the procedure. It remains to be determined whether there is an ideal "target" activated coagulation time for interventional procedures.

Aged↗
PubMed1994

Noninvasive imaging of the cardiovascular system with electron beam computed tomography and magnetic resonance imaging.

Two new noninvasive imaging modalities have emerged in recent years that provide images of the heart and great vessels with high temporal and spatial resolution: electron beam (or ultrafast) computed tomography and magnetic resonance imaging. Because both modalities acquire images in three dimensions, they can provide unique diagnostic information above and beyond that of more traditional noninvasive modalities such as two-dimensional echocardiography and radionuclide techniques. This review discusses the technical evolution and clinical application of these two imaging techniques, with particular emphasis on progress made over the past year. Specific areas addressed for each include technical aspects and clinical applications from both the imaging and physiology perspective.

Cardiomyopathies↗
PubMed1994

Clopidogrel is more effective than aspirin as adjuvant treatment to prevent reocclusion after thrombolysis.

Clopidogrel is a thienopyridine derivative and a potent inhibitor of ADP-induced platelet aggregation. We compared clopidogrel with aspirin as an adjunctive treatment to tissue-type plasminogen activator (t-PA) for thrombolysis and reocclusion. Thrombosis was induced in coronary arteries of 32 dogs by injuring the endothelium with an electric charge. Coronary blood flow velocity was monitored by a pulsed Doppler flow probe placed around the artery. After the artery had been occluded by a thrombus for 3 continuous hours, each animal was given one of the following intravenous treatments: 1) t-PA (80 micrograms/kg + 8 micrograms.kg-1.h-1) and heparin (200 U/kg) (group 1, n = 7); 2) t-PA, heparin, and aspirin (5 mg/kg) (group 2, n = 8); 3) t-PA, heparin, and clopidogrel (5 mg/kg) (group 3, n = 9); and 4) t-PA, heparin, and clopidogrel (10 mg/kg + 2.5 mg.kg-1.h-1) (group 4, n = 8). After treatment, thrombolysis developed in 45 +/- 12 min in group 1, 39 +/- 10 min in group 2, 39 +/- 10 min in group 3, and 27 +/- 10 min in group 4 (compared with group 1, P > 0.05). After thrombolysis, reocclusion occurred in 5 of 5 dogs in group 1 and 7 of 7 in group 2, but only 2 of 7 in group 3 and none of 7 in group 4 (compared with groups 1 and 2, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Blockade of platelet membrane glycoprotein Ib receptors delays intracoronary thrombogenesis, enhances thrombolysis, and delays coronary artery reocclusion in dogs.

Von Willebrand factor and platelet membrane glycoprotein Ib receptors interact to mediate platelet adhesion and thrombogenesis in stenosed and endothelium-injured arteries. We wished to determine whether blocking glycoprotein Ib receptors with a recombinant von Willibrand factor binding domain (VCL) increases the time required for thrombus formation after injury to the coronary arteries. We also wished to determine whether, after thrombolysis with tissue plasminogen activator (TPA), VCL delays or protects against coronary artery reocclusion. Twenty-seven dogs were treated with either saline, VCL, or aspirin before thrombosis was induced in their coronary arteries by electrical injury. The time from injury to the formation of occlusive thrombi was significantly greater with VCL (70 +/- 10 minutes) and aspirin (69 +/- 20 minutes) than with saline (18 +/- 3 minutes, P < .001 and P < .05). Thrombosis was induced in 30 other dogs that then received thrombolytic treatment in four groups. Our major finding was that coronary artery reocclusion occurred in 72 +/- 11 minutes after treatment with TPA (80 micrograms/kg + 8 micrograms.kg-1.min-1) and heparin (200 U/kg) (n = 7); in 142 +/- 24 minutes after TPA, heparin, and VCL (4 mg/kg + 2 mg.kg-1.h-1) (n = 7) (compared with TPA and heparin, P < .05); in 74 +/- 13 minutes after TPA, heparin, and aspirin (5 mg/kg) (n = 8); and in 173 +/- 8 minutes after TPA, heparin, VCL, and aspirin (n = 8) (compared with TPA and heparin, P < .001). Thus, VCL increases the length of time required for thrombus formation in coronary arteries, and, when given with TPA and heparin, delays coronary artery reocclusion more effectively than aspirin.

Animals↗
PubMed1993

Optimizing surgical backup for multiple simultaneous percutaneous transluminal coronary angioplasty procedures.

At busy interventional centers, it may be difficult to coordinate surgical backup for multiple simultaneous PTCA procedures. We sought to determine the actual risk of two simultaneous cases requiring surgery, and to identify a group in which multiple simultaneous PTCA procedures could be performed at low risk. We prospectively applied the ACC/AHA A/B/C lesion classification system and an empiric low/medium/high risk classification (based on patients' overall clinical picture) to 1,128 PTCA procedures over a 9 month period; 22 of these patients (1.9%) went directly from the catheterization laboratory to emergency CABG. The incidence of emergency CABG by groups was A-low 1/166, A-medium 1/71, A-high 0/22, B-low 1/116, B-medium 10/481, B-high 2/52, C-low 2/47, C-medium 3/88, and C-high 2/85. The patients were divided into two groups: minimal risk (A + B-low: 3/375 or 0.8%) and increased risk (B-med/high + C: 19/753 or 2.5%). The difference between the groups was significant using chi square with an alpha < 0.05. The risk of two cases requiring surgery at the same time was calculated as a function of the number of simultaneous PTCA procedures performed. Six or fewer minimal risk PTCA, one increased risk plus up to three minimal risk, and a maximum of two increased risk cases were found to have a risk of < 0.001. We conclude that it is possible to identify a group of patients with minimal risk, in whom multiple simultaneous procedures can be performed with a negligible probability of two cases requiring surgery at the same time.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1993

Active oxygen species play a role in mediating platelet aggregation and cyclic flow variations in severely stenosed and endothelium-injured coronary arteries.

A canine model with cyclic flow variations (CFVs) in stenosed and endothelium-injured coronary arteries was used to examine the role of active oxygen species in platelet aggregation in vivo. We studied 90 anesthetized dogs in which the pericardial cavity was opened and the heart was exposed. The velocity of blood flow in the left anterior descending coronary artery (LAD) was monitored by a pulsed Doppler flow probe. In 67 dogs, the LADs were stenosed by applying external constrictors at the site where the endothelium was mechanically injured. CFVs developed in all 67 dogs. Treatment with the antioxidants recombinant human copper-zinc superoxide dismutase (r-h-CuZnSOD), recombinant human manganese superoxide dismutase (r-h-MnSOD), and catalase eliminated platelet aggregation-associated coronary CFVs in 63%, 62%, and 64% of animals, respectively. Intravenous infusion of epinephrine restored CFVs in most dogs. Ketanserin, a serotonin (5-hydroxytryptamine2) receptor antagonist, abolished epinephrine-restored CFVs and eliminated CFVs in dogs in which CFVs had not been eliminated by free radical scavengers. In an additional 23 dogs, the LADs were stenosed but not mechanically injured. For control studies, saline was infused into the LADs of 5 dogs. Xanthine/xanthine oxidase was infused into the LADs of 8 dogs and induced CFVs in 4. Hydrogen peroxide was infused into the other 10 dogs and induced CFVs in 9. Histological analysis of the coronary artery revealed that the intima was significantly injured by the infusion. In ex vivo platelet aggregation studies, the in vivo treatment with r-h-CuZnSOD, r-h-MnSOD, and catalase significantly inhibited platelet aggregation induced by platelet-activating factor. Thus, active oxygen species are involved in mediating platelet aggregation and cyclic flow variations in stenosed and endothelium-injured canine coronary arteries in vivo.

Animals↗
PubMed1993

Use of the activated clotting time in anticoagulation monitoring of intravascular procedures.

The activated clotting time first came into clinical use in the mid-1970s to guide the administration and reversal of heparin during cardiopulmonary bypass procedures. The explosive growth of cardiopulmonary bypass led to the development of automated techniques for measuring activated clotting times. Recent advances in the field of interventional cardiology have emphasized the importance of the coagulation cascade and the need for the prevention of thrombosis with anticoagulant drugs. The activated clotting time has emerged as an important means of monitoring and guiding heparin therapy during invasive intravascular procedures. This review focuses on the following topics: 1) the development of anticoagulation monitoring techniques; 2) current alternatives in bedside anticoagulation monitoring; and 3) the clinical application of activated clotting times outside surgery. Until prospective studies can establish appropriate "target" activated-clotting-time values for interventional procedures, procedural anticoagulation must be guided empirically. Nevertheless, the activated clotting time is extremely useful in the catheterization laboratory, for monitoring heparin therapy and the adequacy of anticoagulation.

Angioplasty, Balloon, Coronary↗
PubMed1993

[Visual and quantitative evaluation of coronarography findings in patients with percutaneous transluminal coronary angiography].

To compare the accuracy of visual and quantitative estimation of coronary angiograms we studied 114 coronary artery stenosis in 62 patients who underwent percutaneous transluminal coronary angioplasty (PTCA) before and after dilatation. Before PTCA the visual estimate of the mean percentage of stenosis severity was 77.2% (SD + 10.1%) which was significantly higher than the value, obtained with quantitative angiography -71.8% (SD 8.8%) (p < 0.01). Immediately after PTCA the visual estimate of the mean residual stenosis was 18.3% (SD + 10.4%), which was significantly lower, than value from quantitative angiography -23.3% (SD + 10.6%) (p < 0.01). The visual estimation of coronary artery stenosis provides quick and inexpensive data which are not accurate in comparison with data from quantitative angiography. Comparison of the visual and quantitative estimates of coronary angiography before PTCA showed visual overestimation of the severity of stenosis. Immediately after PTCA most visual estimates showed an underestimation of the lesion. Thus, the only visual interpretation of the severity of the coronary artery stenosis before and after PTCA leads to optimistic assessment of primary success of the procedure. Quantitative angiography provides more accurate data, but has some limitations, discussed in the paper.

Angioplasty, Balloon, Coronary↗
PubMed1993

An ex vivo model for the reperfusion of explanted human hearts.

A model of an ex vivo-reperfused human heart was developed by using a modified Langendorff coronary perfusion circuit. The technical and physiologic aspects of reestablishing myocardial contractility are described. Preliminary studies were conducted in animals. In the present study, we obtained 12 human hearts that had been arrested with cardioplegic solution and excised from cardiac transplant recipients. The perfusate contained type-specific human donor red blood cells in a lactated Ringer's solution containing 5% dextrose. Myocardial contractility was successfully reestablished in 11 hearts and sustained for an average of 98 minutes (range, 79 to 180 minutes) at a coronary perfusion pressure of 80 mmHg. Left ventricular contraction pressures reached 40 mmHg (against intraventricular balloons at an internal pressure of 50 to 75 mmHg). Partial oxygen pressure (PO2) dropped significantly across the empty beating myocardium (from 498 +/- 40 mmHg to 219 +/- 53 mmHg [mean +/- SD]), but no significant change in hemoglobin saturation was observed. Myocardial failure generally stemmed from edematous changes leading to progressive impairment of myocardial relaxation. The intracoronary insertion of over-the-wire catheters did not adversely affect myocardial function. In conclusion, an ex vivo-supported human heart model has been developed that may have a number of applications, including the preclinical evaluation of new interventional diagnostic and therapeutic techniques aimed at the coronary circulation, and the investigation of myocardial mechanics, preservation, and metabolism.

Adult↗
PubMed1992

Inaccuracies in manufacturer-reported deflated PTCA balloon profiles.

Deflated balloon profile is an important consideration in the selection of PTCA catheters. In order to test the accuracy of manufacturer-reported balloon profiles, we measured deflated shoulder and mid-balloon profile in 107 unused catheters (2.0, 2.5, and 3.0 mm) from 6 manufacturers using a precision hole gauge with a resolution of .001 inches. A significant difference was defined as a discrepancy greater than or equal to 0.003 inches from the manufacturer's reported profile. During Phase I, measurements were obtained at room temperature on catheters directly out of the package. Of the 36 models tested, 21/36 (56%) had measured shoulder profiles that were larger than their reported profile, and 29/36 (81%) had mid-balloon profiles that were larger than their reported profile. During Phase II, measurements were made at body temperature following a 60 second inflation at 120 psi (8.16 atm). Of 33 models tested, 18/33 (55%) had measured shoulder profiles that were larger than their reported profile; 26/33 (79%) had mid-balloon profiles that were larger than their reported profile. The term "profile" is imprecisely defined. Manufacturer-reported deflated PTCA balloon profiles are not always accurate. Independent and uniform testing of balloon profiles is necessary for valid comparisons between balloons and manufacturers.

Angioplasty, Balloon, Coronary↗