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Biomedical subjects

W D Knopf

Publications and source records attributed to W D Knopf.

12 recordsLinked to original sources
PubMed2000

Suture-mediated closure of the femoral access site after cardiac catheterization: results of the suture to ambulate aNd discharge (STAND I and STAND II) trials.

Despite advances in other aspects of cardiac catheterization, manual or mechanical compression followed by 4 to 8 hours of bed rest remains the mainstay of postprocedural femoral access site management. Suture-mediated closure may prove to be an effective alternative, offering earlier sheath removal and ambulation, and potentially a reduction in hemorrhagic complications. The Suture To Ambulate aNd Discharge trial (STAND I) evaluated the 6Fr Techstar device in 200 patients undergoing diagnostic procedures, with successful hemostasis achieved in 99% of patients (94% with suture closure only) in a median of 13 minutes, and 1% major complications. STAND II randomized 515 patients undergoing diagnostic or interventional procedures to use of the 8Fr or 10Fr Prostar-Plus device versus traditional compression. Successful suture-mediated hemostasis was achieved in 97.6% of patients (91.2% by the device alone) compared with 98.9% of patients with compression (p = NS). Major complication rates were 2.4% and 1.1%, and met the Blackwelder's test for equivalency (p <0.05). Median time to hemostasis (19 vs 243 minutes, p <0.01) and time to ambulation (3.9 vs 14.8 hours, p <0.01) were significantly shorter for suture-mediated closure. Suture-mediated closure of the arterial puncture site thus affords reliable immediate hemostasis and shortens the time to ambulation without significantly increasing the risk of local complications.

Cardiac Catheterization↗
PubMed1999

Outpatient PTCA with same day discharge is safe and produces high patient satisfaction level.

Improved technology and enhanced clinical expertise have allowed physicians to become more cost effective and provide better patient care. A prospective, randomized study was done to determine the safety of same day discharge following PTCA. Of 1911 elective PTCA patients, 262 patients (14%) were stratified as low risk and candidates for same day discharge. Of the 262 eligible patients, 90 (34%) were randomized to either an in-patient (n = 47) or outpatient (n = 43) strategy. Similar procedural and clinical outcomes were found between the two groups, with 33 of 43 outpatients (77%) discharged on the same day as the procedure. No late complications (1 and 7 days post procedure) were observed in this outpatient group. Additionally, a satisfaction survey was conducted of all patients and their family members that showed an overwhelming (p < 0.05) preference and comfort with the same day discharge.

Aged↗
PubMed1999

A multicenter randomized trial comparing a percutaneous collagen hemostasis device with conventional manual compression after diagnostic angiography and angioplasty.

OBJECTIVES: A new percutaneous collagen hemostasis device was compared with conventional compression techniques after diagnostic catheterization and angioplasty. Background. Peripheral vascular complications after diagnostic catheterization or more complex interventional procedures, as well as the discomfort of manual compression and prolonged bed rest, represent significant morbidity for invasive cardiac procedures. METHODS: A prospective, multicenter, randomized trial was designed to compare the hemostasis time in minutes and the incidence of vascular complications in patients receiving a vascular hemostasis device with those undergoing conventional compression techniques. RESULTS: After diagnostic catheterization, hemostasis time was significantly less with the vascular hemostasis device than with conventional manual compression (4.1 +/- 2.8 min [n=90 patients] vs. 17.6 +/- 9.2 min [n= 75], p < 0.0001). This difference was greater in patients undergoing angioplasty and was unrelated to the anticoagulation status (4.3 +/- 3.7 min [n = 71 not receiving the heparin], 7.6 +/- 11.6 min [n= 85 receiving heparin], 33.6 +/- 24.2 min [n= 134 control patients not receiving heparin], p < 0.0001 vs. control patients). The time from the start of the procedure to ambulation was slightly less after diagnostic catheterization in patients treated with the device (13.3 +/- 12.1 hours vs. 19.2 +/- 17.8 hours, p < 0.05). It was also less in patients who underwent angioplasty when the device was used after discontinuation of anticoagulation (23.0 +/- 11.1 hours, without heparin), as compared with control compression techniques (32.7 +/- 18.8 hours, p < 0.0001). Time to ambulation was even shorter (16.1 +/- 11.1 h, p < 0.0001) in patients in whom the device was placed immediately after angioplasty while they were still fully anticoagulated with a prolonged activated clotting time (336 +/- 85 s). There were no major complications (surgery or transfusion) after diagnostic catheterization and a low incidence of major complications in patients who underwent angioplasty (0.7% in control patients, 1.4% with the device without heparin, 1.2% with the device and heparin, p = NS). After angioplasty, there was a trend toward fewer hematomas when the device was used in the absence of heparin (4.2% vs. 9.7% in control patients, p = 0.14). CONCLUSION: A new vascular hemostasis device can significantly reduce the puncture site hemostasis time and the time to ambulation without significantly increasing the risk of peripheral vascular complications The role of this technology in reducing complications, length of hospital stay and cost remains to be determined.

Aged↗
PubMed1996

Angiographic and procedural outcome after coronary angioplasty in high-risk subsets using a decremental diameter (tapered) balloon catheter. Tapered Balloon Registry Investigators.

The angiographic and clinical outcomes of 115 patients (129 lesions) treated at 11 clinical centers using a decremental diameter (tapered) balloon catheter were evaluated. The presence of marked tapering of the reference vessel, lesion location involving a bifurcation or anastomosis of a saphenous vein graft, or total coronary occlusion where estimation of the distal vessel size was difficult were indications for this device. The tapered balloon was used as the initial dilatation device in 62 patients (73 narrowings), and as a secondary device in 53 patients (56 narrowings). Lesions selected for tapered balloon angioplasty were generally complex (95% had > or = 1 and 60% had > or = 2 adverse morphologic features). Vessel diameters were larger in the proximal reference segments (3.07 +/- 0.52 mm) than in distal ones (2.48 +/- 0.45 mm) (p<0.001). After tapered balloon angioplasty, the minimal lumen diameter increased from 0.85 +/- 0.34 mm to 2.13 +/- 0.50 mm (p<0.001), and the percent diameter stenosis decreased from 69 +/- 12% to 24 +/- 12% (p<0.001). Coronary dissections occurred in 20% of lesions; they were severe in 4% (National Heart, Lung, and Blood Institute grade C to F). Abrupt closure occurred in 4.3% of patients (2.6% immediate; 1.7% delayed). Procedural success was obtained in 110 patients (96%); major complications (in-hospital death, myocardial infarction, or emergency coronary bypass surgery) occurred in 3 patients (2.7%). Coronary angioplasty using the tapered balloon catheter appears to be a safe and effective technique for the treatment of complex lesion subsets, particularly those involving coronary arteries with marked segmental tapering.

Aged↗
PubMed1995

Transluminal extraction catheter for the treatment of diseased saphenous vein grafts: a multicenter experience.

To evaluate the efficacy, safety, and long-term results of atherectomy using the Transluminal Extraction catheter (TEC), patients with diseased saphenous vein grafts were enrolled in a prospective nonrandomized trial. Patients were followed to hospital discharge for acute complications and underwent routine 6-mo reevaluation with repeat cardiac catheterization to assess restenosis. Atherectomy was performed on 650 graft lesions in 538 consecutive patients (male 81%; mean age 66 yr; range 37-81). Mean graft age was 8.3 yr; (range 0.3-20) with 85% of grafts > 3 yr of age. Complex lesion morphology included thrombus (28%), ulceration (13%), and eccentricity (50%). Lesion success was achieved in 606 lesions (93%) with clinical success in 479 patients (89%). Lesion success was achieved in 90% of thrombus containing lesions, 97% of ulcerated lesions, and 97% of grafts > 3 yr. Complications included nonfatal myocardial infarction in 4 (0.7%) of patients, emergency bypass surgery in 2 (0.41%), and in-hospital death in 17 patients (3.2%). Angiographic follow-up at 6 mo was obtained from 268 lesions in 227 patients. The overall lesion angiographic restenosis rate was 60%. TEC atherectomy can be performed in patients with diseased saphenous vein grafts with high primary success and low complication rates. It is suitable for use in aged grafts, particularly in the presence of thrombus and ulcerations, and may be superior to balloon angioplasty alone in this group of patients.

Adult↗
PubMed1994

Effectiveness of holmium laser-assisted coronary angioplasty. The Holmium Laser Coronary Registry.

The efficacy of holmium laser-assisted angioplasty was studied in 365 narrowings in 331 consecutive patients with coronary artery disease. Clinical indications for study were unstable angina pectoris in 140 patients (42%), stable angina in 136 patients (41%), postmyocardial infarction angina in 35 patients (10.5%), silent myocardial ischemia in 11 patients (3%), acute myocardial infarction in 1 patient (0.3%) and undefined in 8 patients (2%). Coronary morphology characteristics by Multivessel Angioplasty Prognosis Study group criteria were type A in 12.6%, type B1 in 34.2%, type B2 in 27.4% and type C in 25.4%. The laser successfully crossed the total length of the narrowing in 85.2%. Procedural success was 94.2%. Laser alone reduced mean percent luminal narrowing from 88 +/- 11% to 57 +/- 22%. Subsequent balloon angioplasty further reduced the mean luminal narrowing to 23 +/- 18%. Major complication rate was 2.7% (death 0.3%, Q-wave myocardial infarction 0.5%, and emergent bypass surgery 2.7%). Six-month angiographic restenosis (> 50% stenosis) rate was 44%.

Angioplasty, Balloon, Coronary↗
PubMed1993

A multicenter randomized trial comparing a percutaneous collagen hemostasis device with conventional manual compression after diagnostic angiography and angioplasty.

OBJECTIVES: A new percutaneous collagen hemostasis device was compared with conventional compression techniques after diagnostic catheterization and angioplasty. BACKGROUND: Peripheral vascular complications after diagnostic catheterization or more complex interventional procedures, as well as the discomfort of manual compression and prolonged bed rest, represent significant morbidity for invasive cardiac procedures. METHODS: A prospective, multicenter, randomized trial was designed to compare the hemostasis time in minutes and the incidence of vascular complications in patients receiving a vascular hemostasis device with those undergoing conventional compression techniques. RESULTS: After diagnostic catheterization, hemostasis time was significantly less with the vascular hemostasis device than with conventional manual compression (4.1 +/- 2.8 min [n = 90 patients] vs. 17.6 +/- 9.2 min [n = 75], p < 0.0001). This difference was greater in patients undergoing angioplasty and was unrelated to the anticoagulation status (4.3 +/- 3.7 min [n = 71 not receiving heparin], 7.6 +/- 11.6 min [n = 85 receiving heparin], 33.6 +/- 24.2 min [n = 134 control patients not receiving heparin], p < 0.0001 vs. control patients). The time from the start of the procedure to ambulation was slightly less after diagnostic catheterization in patients treated with the device (13.3 +/- 12.1 h vs. 19.2 +/- 17.8 h, p < 0.05). It was also less in patients who underwent angioplasty when the device was used after discontinuation of anticoagulation (23.0 +/- 11.1 h, without heparin), as compared with control compression techniques (32.7 +/- 18.8 h, p < 0.0001). Time to ambulation was even shorter (16.1 +/- 11.1 h, p < 0.0001) in patients in whom the device was placed immediately after angioplasty while they were still fully anticoagulated with a prolonged activated clotting time (336 +/- 85 s). There were no major complications (surgery or transfusion) after diagnostic catheterization and a low incidence of major complications in patients who underwent angioplasty (0.7% in control patients, 1.4% with the device without heparin, 1.2% with the device and heparin, p = NS). After angioplasty, there was a trend toward fewer hematomas when the device was used in the absence of heparin (4.2% vs. 9.7% in control patients, p = 0.14). CONCLUSIONS: A new vascular hemostasis device can significantly reduce the puncture site hemostasis time and the time to ambulation without significantly increasing the risk of peripheral vascular complications. The role of this technology in reducing complications, length of hospital stay and cost remains to be determined.

Aged↗
PubMed1988

Major histocompatibility complex class I and class II expression by myocytes in cardiac biopsies posttransplantation.

A total of 85 cardiac biopsies from patients 23-265 days posttransplant were studied for the correlation of the rejection grade score with the level of major histocompatibility complex (MHC) class I and class II expression on cardiac myocytes and endothelial cells, the quantitative level of leukocytic infiltrate, and the immunophenotype of the leukocytes. Results indicate a lack of absolute correlation between rejection grade scores and levels of MHC antigen expression. Further, a lack of absolute correlation was also seen with quantitation of leukocytic infiltrates and relative levels of MHC antigen expression. Of great interest was our preliminary finding that as early as 4 weeks prior to a rejection episode scored by routine histological criteria as grade 4, cardiac biopsy from the patient demonstrated high levels of MHC class I and class II expression. Similar increases of MHC antigen expression prior to an increase in histological rejection score grades were also noted in serial biopsies of 2 other patients. These data suggest that it may be quite useful to examine levels of MHC antigens on cardiac biopsies posttransplantation as an additional parameter for monitoring of cardiac rejection episodes.

Antigens, Differentiation↗
PubMed1988

Characterization of human cardiac infiltrating cells post transplantation. 1. Phenotypic and functional alloreactivity.

Sequential cardiac biopsies from patients post transplantation were studied for histological evidence of grades of rejection, the immunophenotype of the mononuclear cell infiltrate if present and, in addition, aliquots of the same biopsy were cultured in vitro with medium containing interleukin-2. The exuding mononuclear cells were expanded and bulk cultures and T cell lines resulting from this were evaluated phenotypically and functionally for donor specific alloreactivity. Results of these studies demonstrate: (1) No strict correlation of histological rejection grades with immunophenotype or degree of mononuclear cell infiltrate. (2) The mononuclear cell cultured from 102 biopsies yielded 47 relatively pure CD4+ T cell cultures and 12 cultures enriched for CD4+ T cells, 16 relatively pure CD8+ T cell cultures and 15 cultures enriched for CD8+ T cells, 7 cultures which consisted of dual marked CD4+ CD8+ T cells and 5 which were negative for both CD4 and CD8 but expressed CD3. (3) Of the 59 total CD4+ T cells, 6 demonstrated donor specific CTL reactivity and of the 31 CD8+ T cells, 26 demonstrated donor specific CTL activity. (4) None of the CD4+ CD8+ T cell cultures demonstrated CTL reactivity and all 5 of the CD3+ CD4- CD8- T cell cultures demonstrated potent donor specific CTL activity. (5) Of the 102 cultures, 89 showed donor specific PLT function. (6) High MHC-Class I expression by cardiac myocytes correlated with high frequency of CTL cultures. These data provide a summary of the phenotype and functional analysis of T cells in cardiac biopsy specimens and provide valuable reagents for further studies on the mechanisms involved in human cardiac allograft rejection.

Antibodies, Monoclonal↗
PubMedDate not supplied

Studies of major histocompatibility complex class I/II expression on sequential human heart biopsy specimens after transplantation.

Our previous data indicate that normal human cardiac myocytes do not express detectable levels of major histocompatibility complex (MHC) class II gene products and express only low levels of MHC class I gene products. Examination of heart biopsy samples after transplantation with immunoperoxidase techniques revealed that such myocytes are induced to express high levels of MHC class I/II gene products and that the expression of these gene products appeared to precede histologic evidence of rejection. In efforts to objectively quantitate the level of MHC antigen expression on sequential heart biopsy samples, a radioimmunoassay was set up. Monoclonal antisera was used against human monomorphic MHC class I and II determinants. In addition, to control for the variability in the quantity of biopsy sample, use was made of a monoclonal antisera against human cardiac myosin. A series of three to four sections (4 micron each) of the heart biopsy specimen was treated with each antisera, followed by affinity purified and absorbed iodine 125-labeled goat antimouse immunoglobulin. The mean counts per minute of MHC class I and II was divided by the mean counts per minute obtained with anti-myosin and an index of MHC class I/II derived. Data using such a radioimmunoassay indicate that MHC antigen expression on the heart biopsy specimens does not strictly correlate with histologic rejection grade scores, levels of leukocyte infiltrate, or the immunophenotype of the infiltrating mononuclear cells. Of interest was the finding that an increase in the level of MHC antigen expression occurred before histologic evidence of rejection grades of 3 or greater. In addition, MHC class I antigen expression appeared to increase in heart biopsy samples early during the post-transplant period, followed sequentially by an increase in the level of MHC class II antigen expression. Rejection episodes later during the posttransplant period, however, were accompanied by increased levels of MHC class II antigens. A kinetic analysis of the increase in the levels of MHC class I and II antigens on heart biopsy samples may not only provide a refinement of the histologic scoring of heart biopsy samples for rejection but may also suggest the use of different chemotherapeutic immunosuppressive drug regimens for the treatment of MHC class I as compared with MHC class II dependent rejection episodes.

Antibodies, Monoclonal↗