Publications by authors named "Usman Javed"

24 Publications

  • Page 1 of 1

Incorporation of Wheat Straw Ash as Partial Sand Replacement for Production of Eco-Friendly Concrete.

Materials (Basel) 2021 Apr 20;14(8). Epub 2021 Apr 20.

Department of Civil and Environmental Engineering, School of Engineering and Digital Sciences, Nazarbayev University, Astana 010000, Republic of Kazakhstan.

The depletion of natural sand resources occurs due to excessive consumption of aggregate for concrete production. Continuous extraction of sand from riverbeds permanently depletes fine aggregate resources. At the same time, a major ecological challenge is the disposal of agricultural waste ash from biomass burning. In this study, an environmental friendly solution is proposed to investigate the incorporation of wheat straw ash (WSA) by replacing 0, 5, 10, 15, and 20% of sand in concrete. Characterization results of WSA revealed that it was well-graded, free from organic impurities, and characterized by perforated and highly porous tubules attributed to its porous morphology. A decrease in fresh concrete density and an increase in slump values were attained by an increase in WSA replacement percentage. An increasing trend in compressive strength, hardened concrete density, and ultrasonic pulse velocity was observed, while a decrease was noticed in the values of water absorption with the increase in WSA replacement percentages and the curing age. The WSA incorporation at all replacement percentages yielded concrete compressive strength values over 21 MPa, which complies with the minimum strength requirement of structural concrete as specified in ACI 318-19. Acid resistance of WSA incorporated concrete improved due to the formation of pozzolanic hydrates as evident in Chappelle activity and thermogravimetric analysis (TGA) results of WSA modified composites. Thus, the incorporation of WSA provides an environmentally friendly solution for its disposal. It helps in conserving natural aggregate resources by providing a suitable alternative to fine aggregate for the construction industry.
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http://dx.doi.org/10.3390/ma14082078DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8074297PMC
April 2021

Rejuvenating The Concept Of Work Alienation Through Job Demands-Resources Model And Examining Its Relationship With Emotional Exhaustion And Explorative And Exploitative Learning.

Psychol Res Behav Manag 2019 7;12:931-941. Epub 2019 Oct 7.

Department of Management Sciences, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan.

Purpose: The purpose of the present study was twofold. First, this study examined the relationships of work alienation with explorative learning and exploitative learning. Second, the study tested the role of emotional exhaustion as a mediator of the relationships of work alienation with explorative learning and exploitative learning. Job Demands-Resources model was used as the underlying theoretical foundation to establish these relationships.

Methods: Two-source time-lagged data were collected from 225 middle-level managers and their 222 immediate supervisors in 87 Pakistani firms spanning different industries. Structural equation modeling and bootstrapping were used to test the hypothesized relationships,.

Results: The study revealed that work alienation is negatively related to both explorative learning and exploitative learning. Moreover, the study also established emotional exhaustion as a mechanism underlying the relationships work alienation with explorative learning and exploitative learning by showing that work alienation enhances emotional exhaustion, which, in turn, negatively influences both explorative learning and exploitative learning.

Conclusion: By conceptualizing and providing empirical evidence of the negative relationships of work alienation with explorative learning and exploitative learning, both directly and via emotional exhaustion, the study signified some of the important but largely ignored dynamics of the employment relationship within the current regime of organizational structures. The findings suggest that the managers' sensed estrangement from work and work context need to be addressed, as it can exhaust them emotionally and hinder their search and acquisition of new knowledge and competencies.
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http://dx.doi.org/10.2147/PRBM.S204193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6789178PMC
October 2019

Balloon dilation atrial septostomy for advanced pulmonary hypertension in patients on prostanoid therapy.

Catheter Cardiovasc Interv 2015 May 10;85(6):1066-72. Epub 2014 Dec 10.

Division of Critical Care and Pulmonary Medicine, University of California, Davis Medical Center, Sacramento, California.

Background: Prostanoid therapy improves quality of life and may increase survival in patients with advanced pulmonary hypertension (PH). Balloon dilated atrial septostomy (BDAS) can palliate or bridge to transplantation for patients resistant to medical therapy. The safety and efficacy of BDAS in the prostanoid era has not previously been reported.

Methods: All patients had progressive symptoms despite prostanoid therapy at the time of their first BDAS. Sixteen patients who underwent a total of 23 septostomies between 2004 and 2014 were included in this retrospective case series.

Results: Patients were aged 47.6 years ± 11.3 with 12/16 women. Etiologies included idiopathic (7), methamphetamine (6), scleroderma (1), and anorexigen (2). One patient died within 24 hr post-procedure. Thirty-day and 1-year survival were 75% and 64%, respectively. Six of the septostomies were revisions, including two which were ultimately stented. Three subjects were successfully bridged to transplant. Pulmonary capillary wedge pressure (PCWP) increased from a mean of 13 to 17 mm Hg, cardiac index increased from 2.1 to 2.4 L/min/m(2) , and arterial saturation decreased from 90.7 ± 4.3 to 82.5 ± 5.6%. All non-survivors at 30 days were male and had higher baseline serum creatinine, mean RAP, right ventricular end diastolic pressure (RVEDP), and left ventricle (LV) filling pressures, and lower right ventricle (RV) ejection fraction. Mortality was associated with unchanged post-septostomy cardiac output despite an increase in left ventricular end diastolic pressure (LVEDP).

Conclusions: BDAS may be an alternate therapy for select PH patients who have symptomatic progression despite prostanoid therapy. Survival is comparable to prior reports of BDAS in the pre-prostanoid era.
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http://dx.doi.org/10.1002/ccd.25751DOI Listing
May 2015

Endovascular therapy is effective treatment for focal stenoses in failing infrapopliteal vein grafts.

Ann Vasc Surg 2014 Nov 6;28(8):1823-31. Epub 2014 Aug 6.

Division of Vascular and Endovascular Surgery and the Vascular Center, University of California, Davis Medical Center, Sacramento, CA.

Background: To evaluate the efficacy of endovascular therapy for maintaining patency and preserving limbs among patients with failing infrapopliteal bypass grafts.

Methods: We gathered data from a registry of catheter-based procedures for peripheral artery disease. Of 1554 arteriograms performed from 2006 to 2012, 30 patients had interventions for failing bypass vein grafts to infrapopliteal target vessels. The first intervention for each patient was used in this analysis. Duplex ultrasonography was used within 30 days after intervention and subsequently at 3- to 6-month intervals for graft surveillance.

Results: Interventions were performed for duplex ultrasonography surveillance findings in 21 patients and for symptoms of persistent or recurrent critical limb ischemia in 9 patients. Procedural techniques included cutting balloon angioplasty (83%), conventional balloon angioplasty (7%), and stent placement (10%). Procedural success was achieved in all cases. There were no procedure-related complications, amputations, or deaths within 30 days. By Kaplan-Meier analysis, 37% of the patients were free from graft restenosis at 12 months and 31% were at 24 months. Receiver-operating characteristic analysis indicated that a lesion length of 1.75 cm best predicted freedom from restenosis (C statistic: 0.74). Residual stenosis (P = 0.03), patency without reintervention (P = 0.01), and assisted patency with secondary intervention (P = 0.02) rates were superior for short lesions compared with long lesions. The cohort had acceptable rates of adverse clinical outcomes, with 96% of patients free from amputation at both 12 and 24 months; clinical outcomes were also better in patients with short lesions.

Conclusions: In this single-center experience with endovascular therapies to treat failing infrapopliteal bypass grafts, rates of limb preservation were high, but the majority of patients developed graft restenosis within 12 months. Grafts with longer stenoses fared poorly by comparison. These data suggest that endovascular interventions to restore or prolong graft patency may be associated with maintained graft patency and that close follow-up with vascular laboratory surveillance is essential.
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http://dx.doi.org/10.1016/j.avsg.2014.07.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4318561PMC
November 2014

Transradial interventions with the GuideLiner catheter: role of proximal vessel angulation.

Cardiovasc Revasc Med 2013 Sep-Oct;14(5):275-9. Epub 2013 Aug 22.

University of California, Davis Medical Center, Division of Cardiovascular Medicine, Sacramento, CA.

Background: Transradial coronary intervention (TRI) is increasingly common, but anatomic variations and lack of guide catheter support may increase the complexity of TRI. The GuideLiner catheter (Vascular Solutions, Minneapolis,MN) is a guide catheter extension developed to provide increased guide catheter support. We hypothesized that TRI cases requiring GuideLiner support would have a greater proximal vessel angle and increased lesion angle tortuosity.

Methods: This was a retrospective study reviewing 146 TRI cases performed at a single institution between August 2010 and June 2012. 22 cases (15%) required use of the GuideLiner support catheter. Procedural and angiographic characteristics of all cases were analyzed. Multivariable analysis and receiver operator curves (ROC) were used to analyze predictors of GuideLiner use.

Results: The indications for TRI were similar between both groups. Subjects who required use of the GuideLiner support catheter at the time of TRI were significantly older (69±12years vs. 62±13years, p=0.03). The proximal vessel angle was significantly greater in the cases requiring GuideLiner support (74°±35° vs. 37°±23°, p<0.001). Lesion angle in the Guideliner group was also significantly greater (48°±32° vs. 28°±25°, p<0.001). On multivariable analysis, proximal vessel angle independently predicted the need for GuideLiner support (AOR 1.4 per 10°, p<0.001). A 45° proximal vessel angle predicted the need for GuideLiner use with a sensitivity of 73% and specificity of 74% (c-statistic 0.79). None of the Guideliner TRI cases required conversion to femoral access.

Conclusions: TRIs requiring GuideLiner catheter support had significantly increased lesion complexity and vessel tortuosity. Proximal vessel angulation is significantly associated with the need for GuideLiner use during transradial intervention. Use of the Guideliner facilitated successful completion of PCI despite the use of a wide variety of guiding catheters in this series.
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http://dx.doi.org/10.1016/j.carrev.2013.07.004DOI Listing
April 2014

Mid-term outcomes following endovascular re-intervention for iliac artery in-stent restenosis.

Catheter Cardiovasc Interv 2013 Dec 25;82(7):1176-84. Epub 2013 May 25.

Division of Cardiovascular Medicine and The Vascular Center, Davis Medical Center, University of California, Sacramento, California.

Objectives: We sought to evaluate the procedural characteristics and clinical outcomes of endovascular repair for iliac artery (IA) in-stent restenosis (ISR).

Background: An increasing percentage of patients with complex IA occlusive disease are treated with an endovascular approach, but the outcomes of IA-ISR have not been well described.

Methods: We analyzed all endovascular procedures for treatment of IA-ISR performed at our institution between July 2006-December 2010. The primary outcome was primary patency, defined as <50% stenosis as assessed by clinical examination and duplex ultrasonography (DUS).

Results: Forty-one lesions in 24 patients who underwent repeated endovascular intervention for treatment of IA-ISR. Most lesions were unilateral and involved the common IA (66%). The mean length of ISR was 30.1 ± 14.1 mm with type I (focal) and II (diffuse) ISR occurring with the greatest frequency (34% and 39%, respectively). All patients underwent balloon angioplasty; adjunctive stenting zwas performed in 27 (66%) of the lesions. Type II ISR lesions more frequently required stenting (13/16 lesions, P = 0.02 compared with other patterns of ISR). Procedural success was 100% with a mean gain of 0.13 in the ankle-brachial index (P = 0.001). The 6- and 12-month primary patency rates were 96% and 82%, respectively. The 12-month primary-assisted patency rate was 90% with clinically driven target lesion revascularization (TLR) in three patients.

Conclusions: Endovascular treatment of IA-ISR using an approach of balloon angioplasty followed by selective stenting is associated with high-patency rates and low rates of TLR at 1 year.
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http://dx.doi.org/10.1002/ccd.24975DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3836870PMC
December 2013

Transradial and transfemoral coronary angiography and interventions: 1-year outcomes after initiating the transradial approach in a cardiology training program.

Am Heart J 2013 Mar 17;165(3):310-6. Epub 2012 Nov 17.

Division of Cardiovascular Medicine, University of California, Sacramento, CA, USA.

Background: Limited data are available regarding the safety and feasibility of initiating transradial (TR) diagnostic coronary angiography (CA) and percutaneous coronary intervention (PCI) in cardiology fellowship programs.

Methods: From July 2010 to June 2011, University of California, Davis Medical Center, adopted the TR approach with supervised cardiology fellows as the primary operators. Procedural variables and clinical outcomes of TR and transfemoral (TF) procedures were compared. To minimize confounding variables, ST-elevation myocardial infarction, bypass graft interventions, chronic total occlusions, and procedures with concomitant right heart catheterizations were excluded. To reflect the learning curve of the TR approach, this experience was assessed in 2 sequential 6-month periods.

Results: A total of 402 diagnostic CAs and 255 PCIs were included. Transradial access was used in 141 (35%) of the CAs and in 72 (28%) of PCIs. Within the TR-CA and TF-CA (n = 261) groups, there was no difference between fluoroscopy (10.4 ± 6.0 vs 11.0 ± 8.9, P = .63) or procedure (31.8 ± 11.5 vs 33.2 ± 13.8, P = .55) time throughout the academic year with a significant trend toward lower contrast use (128 ± 52 vs 110 vs 50, P = .04) by the second half. In addition, during the second half of the academic year, the TR-CA showed significantly higher fluoroscopy (11.0 ± 8.9 vs 6.7 ± 6.8, P = .001) and procedure (33.2 ± 13.8 vs 27.2 ± 11.6, P = .0015) times when compared with TF-CA. Transfemoral PCI (n = 183) and TR-PCI showed no significant difference between all fluoroscopy and procedure time and contrast use when comparing the 2 halves of the academic year. When comparing TF with TR within each academic half year, there was no difference within the PCI group. Vascular complications were less with the TR approach. Overall procedural success rates were high, and there were low rates of crossover and periprocedural complications in both the TR and the TF groups.

Conclusion: A TR approach is safe for CA and PCI when performed by supervised operators in training. Although the learning curve for trainees appears slower for TR-CA compared with TF-CA, cardiology fellowship training programs should be encouraged to adopt TR procedures as part of their curriculum.
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http://dx.doi.org/10.1016/j.ahj.2012.10.014DOI Listing
March 2013

Gender-related variation in the clinical presentation and outcomes of critical limb ischemia.

Vasc Med 2013 Feb;18(1):19-26

Department of Internal Medicine, University of California, Davis, Sacramento, CA 95817, USA.

Critical limb ischemia (CLI) is a major cause of limb loss and mortality among patients with advanced peripheral artery disease. Our objective was to evaluate the gender-specific differences in patient characteristics and clinical outcomes among patients with CLI. We performed a retrospective analysis of 97 women and 122 men presenting with CLI who underwent angiography from 2006 to 2010. Baseline demographics, procedural details, and lesion characteristics were assessed for each patient. Kaplan-Meier analysis was used to assess long-term patient and lesion-level outcomes. Cox proportional hazard modeling was used to evaluate the relationship between gender and major adverse cardiovascular events (MACE). Compared to men, women were less likely to have a history of coronary artery disease (39% vs 54%, p = 0.02) or diabetes (57% vs 70%, p = 0.05) but had similar baseline medical therapy. At angiography, women were more likely to have significant femoropopliteal (77% vs 67%, p = 0.02) and multi-level infrainguinal disease (63% vs 51%, p = 0.02). Women were also more likely to undergo multi-vessel percutaneous intervention (69% vs 55%, p = 0.05), but had similar rates of limb salvage after percutaneous intervention or surgical bypass (HR 0.94 [95% CI 0.45-1.94], p = 0.9). During follow-up, women had higher rates of subsequent major adverse cardiovascular events (HR 1.63 [95% CI 1.01-2.63], p = 0.04). In conclusion, women with CLI are more likely to present with femoropopliteal and multi-level infrainguinal disease. Despite similar rates of limb salvage, women with CLI have an increased rate of subsequent major adverse cardiovascular events.
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http://dx.doi.org/10.1177/1358863X13475836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3786085PMC
February 2013

A tale of two balloons: assessment of hemodynamics with atrial septal defect temporary balloon occlusion.

J Invasive Cardiol 2012 May;24(5):248-9

Division of Cardiovascular Medicine, University of California, Davis Medical Center, Sacramento, CA, USA.

We describe two cases in which temporary balloon occlusion (TBO) was used to determine the suitability of atrial septal defect (ASD) closure. These cases underscore the utility of TBO in select patients undergoing percutaneous closure of ASDs.
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May 2012

Angiographically confirmed stent thrombosis in contemporary practice: insights from intravascular ultrasound.

Catheter Cardiovasc Interv 2013 Apr 9;81(5):782-90. Epub 2012 Nov 9.

Davis Medical Center, University of California, Sacramento, California, USA.

Objective: We hypothesized that patients presenting with stent thrombosis (ST) have a high prevalence of stent underexpansion and malapposition when assessed by intravascular ultrasound (IVUS).

Background: IVUS can provide mechanistic insight into mechanical factors, including stent underexpansion, malapposition, and fracture that may predispose to ST.

Methods: All consecutive cases of angiographically confirmed ST from a multicenter registry (from 2005 to 2010) were reviewed. All IVUS images were reviewed off-line for the presence of stent underexpansion, malapposition, and fracture. Kaplan-Meier analysis was used to determine whether use of IVUS at the time of ST was associated with long-term mortality and major adverse cardiovascular events.

Results: IVUS was performed in 32 of 173 subjects with ST (18%). Stent underexpansion was present in 82% of cases and in all cases of early ST, with a mean stent expansion of 0.7 ± 0.23 by MUSIC criteria. Stent malapposition was most frequently observed in very late ST (40%). In-hospital mortality was similar between subjects who had IVUS performed at the time of ST when compared with the non-IVUS group (3.2% vs. 4.3%, P = 0.8). Subjects who had IVUS performed at the time of ST had lower rates of mortality (HR 0.4, 95% CI 0.1-1.6, P =0.2) and major adverse cardiovascular events (HR 0.5, 95% CI 0.2-1.4, P =0.2) at follow-up, but these values were not statistically significant.

Conclusions: There is a high prevalence of stent underexpansion in early ST, while the prevalence of malapposition is higher in very late ST. Use of IVUS during treatment for ST may identify mechanisms underlying the development of ST.
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http://dx.doi.org/10.1002/ccd.24460DOI Listing
April 2013

Percutaneous repair of anterior mitral leaflet perforation.

J Invasive Cardiol 2012 Mar;24(3):134-7

Division of Cardiovascular Medicine, University of California, Davis Medical Center, Sacramento, CA, USA.

A 59-year-old male underwent coronary artery bypass grafting and mitral ring annuloplasty 4 years ago. The procedure was complicated by sternal wound infection. Recently, he presented with multiple admissions for decompensated heart failure with volume overload and pulmonary edema. He was found to have severe mitral regurgitation (MR) and transesophageal echocardiography (TEE) demonstrated severe MR through an anterior mitral leaflet perforation. Due to high surgical risk, he was referred for transcatheter repair of his mitral valve. This case illustrates the first reported use of an Amplatzer atrial septal occluder device for percutaneous mitral leaflet repair using three-dimensional TEE guidance after prior surgical mitral ring annuloplasty repair.
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March 2012

Angiographic stent thrombosis at coronary bifurcations: short- and long-term prognosis.

JACC Cardiovasc Interv 2012 Jan;5(1):57-63

Division of Cardiovascular Medicine, University of California, Davis Medical Center, Sacramento, California 95817, USA.

Objectives: This study sought to describe the presentation, management, and outcomes of patients presenting with angiographic definite stent thrombosis (ST) at coronary bifurcations.

Background: The development of drug-eluting stents has made it increasingly feasible to treat bifurcation lesions percutaneously. However, ST at coronary bifurcations may be associated with greater mortality than ST elsewhere.

Methods: We analyzed a multicenter California registry comprising all cases of angiographic definite ST at 5 academic hospitals from 2005 to 2010. Stenting was defined as occurring at a bifurcation if the main vessel stent crossed a side branch ≥2.0 mm in diameter (provisional single-stent approach), or if there was a prior 2-stent bifurcation approach.

Results: Among 173 cases of angiographic definite ST, we identified 20 cases of ST at coronary bifurcations. Nine of 20 bifurcation ST (45%) occurred with a stent present in both the parent and branch vessel. Eight cases had thrombus present in both the parent and side branch vessels. In-hospital mortality was much higher for subjects with bifurcation ST than ST at a nonbifurcation site (20% vs. 2%, p < 0.0001). During a median follow-up of 2.3 years, ST at a coronary bifurcation was associated with increased long-term mortality (hazard ratio [HR]: 3.3, 95% confidence interval [CI]: 1.4 to 7.7, p = 0.007) and a significantly higher risk for major adverse cardiovascular events (HR: 2.2, 95% CI: 1.04 to 4.8, p = 0.04) relative to ST at a nonbifurcation site.

Conclusions: ST at coronary bifurcations is associated with a higher in-hospital and long-term mortality than ST at nonbifurcation lesions. (Stent Thrombus in Acute Coronary Syndromes; NCT00931502).
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http://dx.doi.org/10.1016/j.jcin.2011.09.015DOI Listing
January 2012

Use of intensive lipid-lowering therapy in patients hospitalized with acute coronary syndrome: An analysis of 65,396 hospitalizations from 344 hospita participating in Get With The Guidelines (GWTG).

Am Heart J 2011 Feb;161(2):418-424.e1-3

University of California, San Francisco-Fresno Medical Education Program, Fresno, CA, USA.

Objectives: The study aimed to analyze the use of intensive lipid-lowering therapy (I-LLT) at discharge in a broad population of patients hospitalized with acute coronary syndrome (ACS).

Background: Early and intensive statin therapy in ACS has been shown to reduce cardiovascular morbidity and mortality. Utilization and predictors of I-LLT among hospitalized ACS patients are not known.

Methods: The GWTG database was analyzed for ACS-related hospitalizations from 2005 to 2009. The use of I-LLT (defined as dose of statin or combination therapy likely to produce > 50% reductions in low-density lipoprotein [LDL]) and less intensive lipid-lowering therapy (LI-LLT) at discharge was assessed. Baseline characteristics and temporal trends in LLT were compared in these 2 treatment groups.

Results: Of 65,396 patients receiving LLT, only 25,036 (38.3%) were treated with an I-LLT regimen. Mean total cholesterol, LDL, and triglycerides were significantly higher in the I-LLT group. Even among those with LDL > 130 mg/dL, 50% or less received I-LLT. Predictors of I-LLT at discharge included LLT before admission, hyperlipidemia, prior coronary artery disease, increasing body mass index, and in-hospital percutaneous coronary intervention. Although there was some temporal improvement in the rate of I-LLT from 2005 to 2007, a decline in use of I-LLT was noted in 2008 and 2009. This was attributed to a sharp reduction in use of ezetimibe in combination with statin, without corresponding increases in intensive statin monotherapy.

Conclusions: In a large cohort of patients admitted with ACS, most of the eligible patients were not discharged on I-LLT. These data suggest the need for better implementation of guideline-recommended intensive statin therapy in patients with ACS.
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http://dx.doi.org/10.1016/j.ahj.2010.12.014DOI Listing
February 2011

Use of intensive lipid-lowering therapy in patients hospitalized with acute coronary syndrome: an analysis of 65,396 hospitalizations from 344 hospitals participating in Get With The Guidelines (GWTG).

Am Heart J 2010 Dec;160(6):1130-6, 1136.e1-3

University of California, San Francisco-Fresno Medical Education Program, Fresno, CA 93703, USA.

Objectives: The study aimed to analyze the use of intensive lipid-lowering therapy (LLT) at discharge in a broad population of patients hospitalized with acute coronary syndrome (ACS).

Background: Early and intensive statin therapy in ACS was shown to reduce cardiovascular morbidity and mortality. Utilization and predictors of LLT among hospitalized ACS patients are not known.

Methods: The GWTG database was analyzed for ACS-related hospitalizations from 2005 to 2009. The use of LLT (defined as dose of statin or combination therapy likely to produce>50% reductions in low-density lipoprotein [LDL]) and less intensive LLT at discharge was assessed. Baseline characteristics and temporal trends in LLT were compared in these 2 treatment groups.

Results: Of 65,396 patients receiving LLT, only 25,036 (38.3%) were treated with an LLT regimen. Mean total cholesterol, LDL, and triglycerides were significantly higher in the LLT group. Even among those with LDL>130 mg/dL, 50% or less received LLT. Predictors of LLT at discharge included LLT before admission, hyperlipidemia, prior coronary artery disease, increasing body mass index, and in-hospital percutaneous coronary intervention. Although there was some temporal improvement in the rate of LLT from 2005 to 2007, a decline in use of LLT was noted in 2008 and 2009. This was attributed to a sharp reduction in use of ezetimibe in combination with statin, without corresponding increases in intensive statin monotherapy.

Conclusions: In a large cohort of patients admitted with ACS, most of the eligible patients were not discharged on LLT. These data suggest the need for better implementation of guideline-recommended intensive statin therapy in patients with ACS.
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http://dx.doi.org/10.1016/j.ahj.2010.08.041DOI Listing
December 2010

Acute myocardial infarction and the five-chambered heart.

Catheter Cardiovasc Interv 2011 Feb;77(2):228-31

Department of Medicine, University of California, San Francisco, Fresno, CA, USA.

The case of a patient presenting with acute inferior ST-elevation myocardial infarction is described. Emergent coronary angiography of the right coronary artery revealed what appeared to be the abrupt drainage of contrast into a large, peculiar cavity or chamber. Echocardiography and cardiac computed tomography demonstrated a giant right coronary aneurysm in the right coronary artery that gave the impression of a "fifth heart chamber." The patient underwent successful surgical resection of the aneurysm. Diagnostic and treatment approaches to giant coronary aneurysms are discussed.
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http://dx.doi.org/10.1002/ccd.22793DOI Listing
February 2011

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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http://dx.doi.org/10.1016/j.thromres.2010.07.021DOI Listing
November 2010

Beta-adrenergic blockers for chronic heart failure.

Cardiol Rev 2009 Nov-Dec;17(6):287-92

Division of Cardiology, UC-San Francisco, Fresno Medical Education Program, Fresno, CA 93703, USA.

Systolic dysfunction and heart failure are major public health problems associated with a significant risk of morbidity and mortality. During the past 2 decades, considerable progress has been made in defining the underlying pathophysiology and the appropriate therapies in heart failure. In patients with chronic heart failure (CHF), sustained sympathetic overactivation leads to down-regulation of beta receptors and uncoupling of the receptors from adenylate cyclase. The clear understanding of the pivotal role of sympathetic overactivation in CHF has led to the evaluation of beta- blocker therapy in CHF. A number of large randomized clinical trials have been conducted with a variety of beta-blockers, and although most of them have shown benefit, there have been differing findings with different molecules. beta-blockers are now considered part of the standard therapy for all patients with symptomatic CHF. Despite the strong evidence supporting their use, beta-blockers continue to be underutilized in CHF.
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http://dx.doi.org/10.1097/CRD.0b013e3181bdf63eDOI Listing
January 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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http://dx.doi.org/10.1161/ATVBAHA.109.195024DOI Listing
January 2010

Frequency of elevated troponin I and diagnosis of acute myocardial infarction.

Am J Cardiol 2009 Jul 4;104(1):9-13. Epub 2009 May 4.

Division of Cardiology, UCSF Fresno Medical Education Program, Fresno, CA, USA.

This study evaluated the incidence and type of acute myocardial infarction (AMI) in a consecutive population with increased troponin I (TnI). AMI has recently been redefined and subclassified. Incidence, demographic data, angiographic findings, and hospital mortality of patients with various AMI subtypes or an increased TnI in the absence of AMI have not been previously reported in a prospective study. Over a 3-month period, all patients admitted from an emergency room or from in-patient services with >1 TnI level >0.04 ng/ml were evaluated and subclassified in AMI subgroups. In-hospital or recent coronary angiograms were reviewed. In-hospital mortality was noted. Of 2,944 patients with serial TnI measurements, 728 had an increased TnI and 701 (23.8%) were evaluated. Two hundred sixteen (30.8% with increased TnI and 42.7% with "rule-out MI" on admission) met criteria for AMI. One hundred forty-three (20.4%) had type 1, 64 (9.1%) had type 2, whereas 461 (65.8%) did not meet criteria for AMI. On multivariate analysis, use of angiography, peak TnI level, hyperlipidemia, and illicit drug use were independently associated with the diagnosis of AMI. TnI of 0.28 ng/ml had a 70% sensitivity and specificity for AMI diagnosis. In conclusion, a minority admitted with increased TnI have AMI by the universal definition. Type 1 is the most common AMI and is associated with higher TnI values and these patients are more likely to undergo angiography. Type 2 AMI is often associated with illicit drug use.
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http://dx.doi.org/10.1016/j.amjcard.2009.03.003DOI Listing
July 2009

Bedside sublingual video imaging of microcirculation in assessing bacterial infection in cirrhosis.

Dig Dis Sci 2009 Dec;54(12):2706-11

Division of Gastroenterology and Hepatology, University of California San Francisco-Fresno Medical Education Program, Community Regional Medical Center, 2823 Fresno Street, 1st Floor, Endoscopy Suite, Fresno, CA 93721, USA.

Bacterial infections are common in cirrhosis and can lead to life-threatening complications. Sidestream dark-field (SDF) imaging has recently emerged as a noninvasive tool for capturing real-time video images of sublingual microcirculation in critically ill patients with sepsis. The objective of this study was to assess the utility of SDF in determining underlying infection in patients with cirrhosis. Sublingual microcirculation was compared among patients with compensated cirrhosis (Group A, n=13), cirrhosis without sepsis (Group B, n=18), cirrhosis with sepsis (Group C, n=14), and sepsis only (Group D, n=10). The blood flow was semi-quantitatively evaluated in four equal quadrants in small (10-25 mm); medium (26-50 mm); and large (51-100 mm) sublingual capillaries. The blood flow was described as no flow (0), intermittent flow (1), sluggish flow (2), and continuous flow (3). The overall flow score or microvascular flow index (MFI) was measured for quantitative assessment of microcirculation and predicting power for concurrent infection in cirrhosis. Marked impairment was observed at all levels of microvasculature in Groups B and C when compared with Group A. This effect was restricted to small vessels only when Group B was compared with Group C. MFI<1.5 was found to have highest sensitivity (100%) and specificity (100%) for infection in decompensated cirrhosis. SDF imaging of sublingual microcirculation can be a useful bedside diagnostic tool to assess bacterial infection in cirrhosis.
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http://dx.doi.org/10.1007/s10620-008-0664-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2778688PMC
December 2009

Statins in heart failure.

Cardiol Clin 2008 Nov;26(4):573-87

Division of Cardiology, Veterans Affairs Central California Health Care System, University of California, San Francisco Program at Fresno, Fresno, CA 93703, USA.

This article reviews the results from several recent reports describing the safety and efficacy of statin therapy in the setting of heart failure. It additionally discusses the ongoing controversy regarding the lipid paradox and possible mechanisms responsible for potential benefit of statin therapy in heart failure.
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http://dx.doi.org/10.1016/j.ccl.2008.06.006DOI Listing
November 2008

Angiotensin receptor blockers: novel role in high-risk patients.

Cardiol Clin 2008 Nov;26(4):507-26

Cardiology Section, Cardiovascular Research, UCSF Fresno Medical Education Program, UCSF School of Medicine, Fresno, CA 93703, USA.

The identification of patients at high risk for cardiovascular events is imperative in the reduction of cardiovascular mortality and morbidity. Although coronary artery disease, peripheral arterial disease, cerebrovascular disease, hypertension, and diabetes mellitus contribute to the risk of developing cardiovascular events, we are now faced with emerging fronts because of an increase in life expectancy and the epidemic of hypertension, obesity, metabolic syndrome, and diabetes. Recent data emphasize the beneficial role of renin-angiotensin-aldosterone system (RAAS) blockers. This article addresses the role of RAAS activation in the high-risk metabolic milieu and the role of angiotensin receptor blockers in targeting and inhibiting the RAAS for cardiovascular protection.
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http://dx.doi.org/10.1016/j.ccl.2008.07.001DOI Listing
November 2008
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