Publications by authors named "Cyrus Buhari"

7 Publications

  • Page 1 of 1

Femoral micropuncture or routine introducer study (FEMORIS).

Cardiology 2014 9;129(1):39-43. Epub 2014 Jul 9.

Division of Cardiology, Department of Internal Medicine, UCSF Fresno Medical Education Program, Fresno, Calif., USA.

Objectives: The Micropuncture® 21-gauge needle may reduce complications related to vessel trauma from inadvertent venous or posterior arterial wall puncture.

Methods: This was a single-center, multiple-user trial. Four hundred and two patients undergoing possible or definite percutaneous coronary intervention (PCI) were randomized 1:1 to an 18-gauge versus a 21-gauge needle. Patients and personnel pulling the sheaths and performing the follow-up were blinded. The primary end point was a composite of access bleeding. Events were tabulated following sheath removal, ≤ 24 h after the procedure and at the follow-up (at 1-2 weeks). End points were blindly adjudicated.

Results: The event rate overall was 12.4% and did not differ significantly between groups, although the 21-gauge needle was found to reduce events by more than one third. An exploratory subgroup analysis of prespecified variables indicated that: patients who did not undergo PCI or elective procedures, female patients and those with a final sheath size of ≤ 6 Fr all had a significant or near-significant reduction of complications with Micropuncture.

Conclusions: Although no significant differences between the use of the 18- and 21-gauge needles were observed, there was a 50-75% reduction with Micropuncture in several subgroups. The study was terminated prematurely. Access site complications may be reduced by the use of the 21-gauge needle, particularly when the risk of bleeding is not high. Further multicenter data will be required to confirm these hypothesis-generating observations.
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May 2015

Treating and preventing no reflow in the cardiac catheterization laboratory.

Curr Cardiol Rev 2012 Aug;8(3):209-14

UCSF Fresno Division of Cardiology, 2823 Fresno Street, 5th Floor, Fresno, CA 93721, USA.

The no reflow phenomenon can happen during elective or primary percutaneous coronary intervention. This phenomenon is thought to be a complex process involving multiple factors that eventually lead to microvascular obstruction and endothelial disruption. Key pathogenic components include distal atherothrombotic embolization, ischemic injury, reperfusion injury, and susceptibility of coronary microcirculation to injury. Thus, pharmacologic and mechanical strategies to prevent and treat no reflow target these mechanisms. Specifically, pharmacologic therapy consisting of vasodilators and antiplatelet agents have shown benefit in the treatment of no-reflow and mechanical therapies such as distal protection and aspiration thrombectomy have also shown benefit.
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August 2012

Acute cigarette smoke exposure reduces clot lysis--association between altered fibrin architecture and the response to t-PA.

Thromb Res 2010 Nov 1;126(5):426-30. Epub 2010 Sep 1.

Division of Cardiovascular Medicine, University of California San Francisco, Fresno, CA 93721, USA.

Background: Enhanced thrombolysis is a proposed mechanism for reduced mortality in cigarette smokers with STEMI ("smoker's paradox"). The mechanisms remain unclear but studies suggest fibrin architecture (FA) may affect thrombolysis. Our group has previously shown that acute cigarette smoke exposure (CSE) alters FA. This study was done to evaluate the association between FA, thrombolysis and CSE.

Methods And Results: Otherwise healthy smokers (n=22) were studied before and after smoking two cigarettes. Non-smokers (n=22) served as controls. Two ex-vivo models were used to evaluate clot lysis of venous blood and these data were compared to FA as determined by SEM. In the first model, clot lysis in a glass tube at 60minutes after addition of t-PA was measured. The second model quantified lysis utilizing thromboelastography. With the latter, after a clot reached maximum strength, t-PA was added and clot lysis at 60min was noted. SEM studies were performed on platelet poor plasma mixed with thrombin and FA was examined at 20K. Clot lysis was similar in both groups except that post-smoking, TEG showed a significantly lower lysis compared to pre- and non-smoking clots. SEM analysis showed significantly thinner fibers and denser clots post-smoking.

Conclusions: Venous clots from smokers failed to show an enhanced lysis when exposed to t-PA. In fact, acute CSE was associated with changes in FA and increased resistance to thrombolysis. These findings in part may explain enhanced thrombogenicity but suggest that mechanisms other than enhanced fibrinolysis are likely to be responsible for "smoker's paradox."
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November 2010

Effects of cigarette smoke exposure on clot dynamics and fibrin structure: an ex vivo investigation.

Arterioscler Thromb Vasc Biol 2010 Jan 8;30(1):75-9. Epub 2009 Oct 8.

Division of Cardiovascular Medicine, University of California San Francisco, Fresno, 2823 N Fresno Street, Fresno, CA 93721, USA.

Objective: The purpose of this study was to examine the effect of cigarette smoke exposure (CSE) on clot dynamics and fibrin architecture and to isolate the relative contribution of platelets and fibrinogen to clot dynamics.

Methods And Results: From young healthy males smokers (n=34) and nonsmokers (n=34) a baseline blood was drawn, and smokers had another blood draw after smoking 2 regular cigarettes. Using thromboelastography (TEG) the degree of platelet-fibrin interaction was measured. In additional experiments, abciximab (20 microg/mL) was added to the smokers samples (n=27) to reduce the effects of platelet function from the TEG parameters. The maximum clot strength (G) obtained with abciximab measured mainly the contribution of fibrinogen to clot strength (GF). By subtracting GF from G, the contribution of platelets to clot strength (GP) was presumed. A significant difference was found for all TEG parameters between nonsmokers versus postsmoking and pre- versus postsmoking samples. Postsmoking both GF and GP were significantly higher as compared to presmoking. On electron microscopy and turbidity analysis, postsmoking fibrin clots were significantly different compared to presmoking and nonsmoking samples.

Conclusions: Acute CSE changes clot dynamics and alters fibrin architecture. Both functional changes in fibrinogen and platelets appear to contribute to heightened thrombogenicity after acute CSE.
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January 2010

Initial stability of cemented femoral stems as a function of surface finish, collar, and stem size.

J Bone Joint Surg Am 2004 Jan;86(1):106-15

Biomechanics Laboratory, Los Angeles Orthopaedic Hospital/University of California at Los Angeles, Los Angeles, CA 90007-2697, USA.

Background: The optimum surface roughness of cemented femoral stems used for total hip replacement is a subject of controversy. While rougher surfaces provide stronger cement adhesion, it has been hypothesized that polished, tapered, noncollared stems settle into the cement mantle, providing improved stability. However, the effects of surface finish on the stability of straight, cemented stems tapered only in the coronal plane are not known.

Methods: Using composite model femora, we assessed the initial stability of a straight, cemented femoral stem as a function of surface roughness, the presence or absence of a collar, stem size, and the resultant cement thickness under simulated walking and stair-climbing loads. Otherwise identical stems were manufactured with polished or rough surfaces, with or without a collar, in two different sizes. We isolated these three variables and compared their relative contributions to the motion at the stem-cement interface throughout cyclic loading. We defined three indicators of stability: per-cycle motion, rate of migration, and final migration.

Results: Surface roughness had a greater influence on per-cycle motions than did the presence or absence of a collar or cement thickness. Specifically, in the medial-lateral direction, per-cycle motion of polished stems was 43 micro m greater than that of rough stems (p < 0.01). None of the per-cycle motions decreased over the 77,000 load cycles. In contrast, with all stems, the rate of migration decreased over the course of cyclic loading, but the rate of migration of the polished stems was greater than that of the rough stems. Final migrations of the stems over the course of loading were generally distal, medial, and into retroversion. Compared with rough stems, polished stems had 8 to 18 micro m more axial migration (p < 0.001), 48 micro m more anterior-posterior migration (p < 0.001), and 0.4 degrees more rotational migration (p = 0.01).

Conclusions: and

Clinical Relevance: The results indicated that, for cemented, straight femoral stems tapered only in the coronal plane, a rough surface offers the advantage of less per-cycle motion. These results may apply to widely used cemented stem designs based on the profile of the original Charnley femoral component, which has approximately parallel anterior and posterior aspects.
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January 2004