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Biomedical subjects

Samin K Sharma

Publications and source records attributed to Samin K Sharma.

At least 19 recordsLinked to original sources
PubMed2006

Coronary interventional devices: balloon, atherectomy, thrombectomy and distal protection devices.

With increased operator experience and improved device technology, there has been a constant growth in the number of complex lesions (ie, thrombotic lesions, diffuse lesions,calcified lesions, nondilatable rigid lesions, ostial lesions, bifurcations, and chronic total occlusions) attempted by interventionalists with the use of drug-eluting stents. Although coronary stent implantation remains the mainstay and ultimate step for the treatment of most coronary lesions, adjunctive devices may be essential for lesion preparation in some cases (5%-10%) to allow stent deployment and expansion and prevent distal embolization. Thrombectomy and distal protection devices have shown to be effective in the interventions of saphenous vein graft lesions, although their use remains unproven in acute myocardial infarctions.

Angioplasty, Balloon, Coronary↗
PubMed2006

Coronary bifurcation lesions.

Treatment of coronary bifurcation lesions represents a challenging area in interventional cardiology, but recent advances in percutaneous coronary interventions have led to a dramatic increase in the number of patients successfully treated percutaneously. When compared with nonbifurcation interventions, bifurcation interventions have a lower rate of procedural success, higher procedural costs, longer hospitalization, and a higher rate of clinical and angiographic restenosis. The recent introduction of drug-eluting stents has resulted in a lower event rate and reduction of main vessel restenosis compared with historical controls. Side branch ostial residual stenosis and long-term restenosis remain a problem, however. Although stenting the main vessel with provisional side branch stenting seems to be the prevailing approach, in the era of drug-eluting stents, various two stent techniques have emerged to allow stenting of the large side branch also.

Angioplasty, Balloon, Coronary↗
PubMed2006

A case of symptomatic coronary artery fistula.

BACKGROUND: A 57-year-old man presented with dyspnea and presyncope on exertion. He had previously been diagnosed with hypertension, hypercholesterolemia and atrial fibrillation. A soft (grade II/VI), dynamic continuous murmur was noted in the mid precordium. INVESTIGATIONS: Electrocardiography, stress echocardiography and coronary angiography. DIAGNOSIS: Right coronary artery to coronary sinus fistula with coronary steal, exertional ischemia and ventricular arrhythmia. MANAGEMENT: Coil embolization of coronary left ventricular fistula.

Arteriovenous Fistula↗
PubMed2006

Coronary artery restenosis: vascular biology and emerging therapeutic strategies.

Percutaneous coronary intervention with drug-eluting stents is currently the preferred approach to the treatment of obstructive coronary stenoses. Large, randomized trials have demonstrated a significant reduction in the incidence of restenosis after drug-eluting stent placement compared with balloon angioplasty or bare metal stents across a wide range of lesions. Furthermore, these stents have appeared to be effective in maintaining the luminal patency at follow up for up to 2-4 years. Concerns regarding the potential adverse effects of drug-eluting stents, such as aneurysm formation in arteries secondary to drug toxicity or hypersensitivity, as well as the overdependence on antiplatelet therapy for a protracted period to prevent subacute thrombosis, have been raised. However, evidence from large studies has not demonstrated any significant increase in the incidence of such adverse events. Future approaches to treating coronary stenoses involve technical modifications, such as direct stenting, accelerating endothelialization with gene delivery of nitric oxide donors, smooth muscle cell growth inhibitors after stent placement, biodegradable stents and concurrent use of local molecule delivery and oral chemotherapy. Ongoing large-scale postmarketing surveillance studies are expected to provide credible answers to the concerns regarding the safety of these stents.

Animals↗
PubMed2006

Improved outcome with AngioJet thrombectomy during primary stenting in acute myocardial infarction patients with high-grade thrombus.

BACKGROUND: Primary stenting during acute myocardial infarction (MI) is often complicated by slow-flow/no-reflow due to distal embolization of intracoronary thrombus. The AngioJet thrombectomy catheter has been utilized in this setting in order to limit distal embolization and improve flow. The effect of AngioJet during primary stenting in acute MI with high-grade thrombus (greater than or equal to grade 3, as per thrombolysis in MI [TIMI] classification) is not known. METHODS: We analyzed 95 consecutive acute MI patients with thrombus grade > or = 3 who underwent primary stenting with AngioJet (n = 52) and without AngioJet (n = 43) for epicardial and microvascular flow, and followed for 30-day major adverse cardiac events (MACE) and 1-year survival. Baseline characteristics and in-hospital events were obtained from the interventional database. Two independent operators analyzed pre- and post-procedure TIMI flow rates, corrected TIMI frame count (CTFC) and TIMI myocardial perfusion grade (TMPG). RESULTS: Baseline clinical and angiographic characteristics were comparable between the two groups. AngioJet use was associated with better TIMI flow, TMP grade, CTFC and a trend towards lower 30-day and 1-year MACE. Use of AngioJet thrombectomy prior to stenting of acute MI patients with high-grade thrombus improves epicardial and microvascular flow, with a trend toward better short- and long-term outcome.

Aged↗
PubMed2005

Effectiveness of the stent pull-back technique for nonaorto ostial coronary narrowings.

Coronary stenting of nonaorto ostial coronary lesions is challenging because of plaque shift into the main vessel, triggering the use of additional stents. Furthermore, inappropriate coverage of the ostium of the side branch increases the risk of restenosis and target vessel revascularization (TVR). To improve the treatment of nonaorto ostial coronary lesions with a novel interventional technique, we tested the hypothesis that inflating a balloon in the main vessel before stenting the side branch (stent pull-back technique) will limit plaque shifting and reduce the use of additional stents. In addition, proper coverage of the side branch ostium may also reduce 8-month TVR. A case-control design with 100 consecutive patients who underwent drug-eluting stent placement was performed; 55 patients were treated with the stent pull-back technique and 45 patients with a conventional stent technique. Procedural success was 100% for the 2 techniques. The use of additional stents was reduced in the stent pull-back group compared with the conventional stent group (2% vs 18%, p = 0.007). A tendency toward lower ostial miss was also observed in the stent pull-back group (4% vs 13%, p = 0.11). The incidence of in-hospital and 30-day cardiac events was similar between the 2 groups. TVR was lower in the stent pull-back group compared with the conventional group (5% vs 20%; p = 0.03). In conclusion, the stent pull-back technique improves the percutaneous treatment of nonaorto ostial coronary lesions. The technique is associated with a lower use of additional stents and improved clinical outcome, reducing TVR at 8 months of follow-up.

Case-Control Studies↗
PubMed2005

Results of repeat balloon valvuloplasty for treatment of aortic stenosis in patients aged 59 to 104 years.

Balloon aortic valvuloplasty (BAV) may be considered a palliative procedure that is performed in patients who have severely symptomatic aortic stenosis and a prohibitive surgical risk. However, due to poor early survival rates, most previous studies have involved a single BAV procedure. We analyzed long-term outcomes in patients who had severe aortic stenosis and BAV that incorporated repeat procedures to maintain symptom relief and increase survival rate. We retrospectively analyzed 212 consecutive nonsurgical patients (59 to 104 years old) who had severe calcific aortic stenosis and underwent 282 cumulative BAV procedures. Demographic, procedural, and follow-up mortality data were collected. BAV was performed with single or incremental balloon dilatation to obtain a postprocedural transaortic gradient close to 1/3 of the baseline gradient. Peak transaortic gradient after BAV decreased from 55 +/- 22 to 20 +/- 11 mm Hg and aortic valve area increased from 0.6 +/- 0.2 to 1.2 +/- 0.3 cm(2). Mean follow-up duration was 32 +/- 18 months. During follow-up, 24% of patients underwent a second BAV and 9% of patients underwent a third BAV. Duration of symptom alleviation after the first, second, and third BAV procedures were 18 +/- 3, 15 +/- 4, and 10 +/- 3 months, respectively. Median survival rate after BAV was 35 months. Survival rates 1, 3, and 5 years after the procedure were 64%, 28%, and 14% respectively. Patients who underwent repeat BAV had higher 3-year survival rates than did patients who underwent 1 BAV (p = 0.01). Therefore, repeat BAV is a viable treatment strategy in nonsurgical patients who have severe calcific aortic stenosis, because it provides a median survival rate of approximately 3 years and maintains clinical improvement.

Age Factors↗
PubMed2005

Simultaneous kissing drug-eluting stent technique for percutaneous treatment of bifurcation lesions in large-size vessels.

Treatment of bifurcation lesions is associated with high procedural complications and restenosis rate due to plaque shift, suboptimal angiographic results, difficulty in crossing the stent struts, and incomplete coverage of the side-branch ostium. The simultaneous kissing stent (SKS) technique involves two stents, one in main vessel (MV) and one in the side branch (SB) with overlapping stents in the MV proximally, extending proximally the carina of bifurcation. We analyzed our first 200 consecutive patients (202 lesions) who underwent SKS technique for true bifurcation lesions using sirolimus eluting stents, with a minimum follow-up of 6 months. Procedural success was 100% for MV and 99% for SB using SKS technique, with clinical success rate of 97%. In-hospital and 30-day major adverse cardiac events were 3% and 5%, respectively, with a procedure time of 36 +/- 14 min. At mean follow-up of 9 +/- 2 months, the incidence of target lesion revascularization was 4% in the entire group. Therefore, SKS technique using sirolimus-eluting stents may become an effective treatment strategy for large-size bifurcation lesions. However, in order to establish its superiority, SKS technique needs to be compared in a randomized manner with conventional stent techniques.

Blood Vessel Prosthesis↗
PubMed2005

Effect of nonionic radiocontrast agents on the occurrence of contrast-induced nephropathy in patients with mild-moderate chronic renal insufficiency: pooled analysis of the randomized trials.

Contrast-induced nephropathy (CIN) is associated with high morbidity and mortality. The recent literature contains numerous clinical trials with similar design, endpoints, and patient populations, describing the nephrotoxic effects of various contrast agents, which are higher with ionic vs. nonionic contrast agents. The difference in the incidence of CIN with nonionic contrast agents may be due to the number of benzene rings (monomer vs. dimer), iodine content, osmolality, and viscosity of the individual contrast agents. We evaluated the recently published data from clinical studies with nonionic iodinated contrast agents in patients with preexisting chronic renal insufficiency (CRI) and report the results of pooled analysis of data from recent prospective independent studies of CIN with various nonionic contrast agents. Review of the recent literature revealed that the CIN incidence varies across the studies reviewed and the contrast agents used. The highest incidence of CIN was observed in studies using iohexol or ioxilan. Results of the pooled analysis of nonionic contrast agents (with more than one randomized study) showed a similar incidence of CIN after iodixanol and iopamidol in patients with preexisting CRI, while both agents showed a significantly lower incidence of CIN compared to iohexol. Since iodixanol is more expensive than iopamidol, this observation may be clinically relevant.

Contrast Media↗
PubMed2005

Two-year clinical follow-up of 90Sr/90 Y beta-radiation versus placebo control for the treatment of in-stent restenosis.

BACKGROUND: It is an ongoing concern that intracoronary brachytherapy may possibly just delay the problem of in-stent restenosis ("late catch up"). For gamma-radiation, 3 placebo-controlled studies have shown the maintenance of the initially positive effect after 2 years, but similar data do not exist for beta-radiation. STents And Restenosis Trial (START) was the first placebo-controlled randomized trial for in-stent restenosis with beta-radiation; herein, we report the 2-year clinical follow-up. METHODS AND RESULTS: Two hundred and forty-four patients were randomized to active treatment, 232 patients to placebo (nonactive source train) treatment. The primary end point of efficacy was target vessel revascularization (TVR); primary safety end point was any major adverse cardiac event (MACE) at 8 months and 2 years. Two-year clinical outcome in patients receiving brachytherapy was based on 195 of 244 original patients (79.9%) and in the placebo arm on 183 of 232 original patients (78.9%). TVR was significantly reduced by 25%; from 36.6% (placebo) to 27.5% (brachytherapy) remained significant after 2 years (RR .7 [.57-.98], 95% CI -9.2 [-17.5-0.8]). The Kaplan-Meier analysis for TVR and MACE showed improvement beginning approximately 90 days after radiation and remained almost constant for the 2 following years. Freedom from TVR was significantly increased from 62.4% +/- 3.8% to 71.6% +/- 3.3% (P = .027) and freedom from MACE from 58.9% +/- 3.7% to 68.0% +/- 3.4% (P = .035). CONCLUSIONS: The START trial shows for the first time that the initial beneficial effects of intracoronary brachytherapy with beta-radiation using 90 Sr/ 90 Y are maintained at 2-year clinical follow-up period.

Aged↗
PubMed2005

Restenosis and drug-eluting stents.

The implantation of intracoronary stents for the treatment of coronary atherosclerotic disease is one of the most common percutaneous procedures. While the procedure brings long-term benefit for a large percentage of patients, a significant number of patients experience in-stent restenosis (ISR). ISR may be caused by a number of biological and procedural factors, including lesion characteristics as well as co-existing disease states like diabetes. Many strategies have been developed to try to reduce the incidence of ISR. The primary methods include systemic pharmacologic treatments, as well as attempts at modifying stents to reduce their role in the development of ISR. Drug-eluting stents are one such modality, and are expected to become a widely used tool in the field of interventional cardiology. This review will focus on the pathophysiology of ISR and possible ways to prevent it, including drug-eluting stents.

Anticoagulants↗
PubMed2004

Simultaneous kissing stents (SKS) technique for treating bifurcation lesions in medium-to-large size coronary arteries.

The treatment of bifurcation lesions (BLs) is associated with high procedural complication and restenosis rates. Two techniques of BL interventions were compared: the simultaneous kissing stents (SKS) technique, involving 2 stents, 1 in the main vessel and 1 in the side branch (n = 100), and the conventional stent strategy (CSS) technique, involving a stent in the main vessel and provisional stenting for the side branch (n = 100). In-hospital and 30-day major adverse cardiac events were greater in the CSS group, with significantly less procedure time with the SKS technique. The incidence of target lesion revascularization was 5% in the SKS group and 18% in the CSS group (p = 0.007). Therefore, the SKS technique seems to be rapid, safe, and effective for the treatment of medium- to large-size BLs, with a trend toward fewer acute complications and promising mid-term results.

Abciximab↗
PubMed2004

Plaque neovascularization is increased in ruptured atherosclerotic lesions of human aorta: implications for plaque vulnerability.

BACKGROUND: Growth of atherosclerotic plaques is accompanied by neovascularization from vasa vasorum microvessels extending through the tunica media into the base of the plaque and by lumen-derived microvessels through the fibrous cap. Microvessels are associated with plaque hemorrhage and may play a role in plaque rupture. Accordingly, we tested this hypothesis by investigating whether microvessels in the tunica media, the base of the plaque, and the fibrous cap are increased in ruptured atherosclerotic plaques in human aorta. METHODS AND RESULTS: Microvessels, defined as CD34-positive tubuloluminal capillaries recognized in cross-sectional and longitudinal profiles, were quantified in 269 advanced human plaques by bicolor immunohistochemistry. Macrophages/T lymphocytes and smooth muscle cells were defined as CD68/CD3-positive and alpha-actin-positive cells. Total microvessel density was increased in ruptured plaques when compared with nonruptured plaques (P=0.0001). Furthermore, microvessel density was increased in lesions with severe macrophage infiltration at the fibrous cap (P=0.0001) and at the shoulders of the plaque (P=0.0001). In addition, microvessel density was also increased in lesions with intraplaque hemorrhage (P=0.04) and in thin-cap fibroatheromas (P=0.038). Logistic regression analysis identified plaque base microvessel density (P=0.003) as an independent correlate to plaque rupture. CONCLUSIONS: Thus, neovascularization as manifested by the localized appearance of microvessels is increased in ruptured plaques in the human aorta. Furthermore, microvessel density is increased in lesions with inflammation, with intraplaque hemorrhage, and in thin-cap fibroatheromas. Microvessels at the base of the plaque are independently correlated with plaque rupture, suggesting a contributory role for neovascularization in the process of plaque rupture.

Adult↗
PubMed2004

Anemia is an independent predictor of mortality after percutaneous coronary intervention.

OBJECTIVES: The aim of the present study was to assess whether anemia is a marker of increased risk during interventional procedure and poor midterm survival after percutaneous coronary intervention (PCI). BACKGROUND: Anemia is associated with increased risk of mortality in patients with heart failure and myocardial infarction (MI). METHODS: We examined the outcomes of 6,116 consecutive PCI patients based on the hemoglobin (Hb) value before the interventional procedure. Patients were divided into three groups based on the baseline Hb level (g/l): Hb <10 = severe anemia; Hb 10 to 12 = mild anemia; Hb >12 = no anemia. RESULTS: The presence of anemia is associated with higher 30-day major adverse cardiac events, post-PCI peak troponin and creatine kinase-MB fraction, and a longer length of stay. After controlling for multiple covariates, significant difference in one-year survival was noted in the anemic groups compared with no anemia group (adjusted hazard ratio for Hb 10 to 12: 1.5 [95% confidence interval 1.3 to 1.8]; for Hb <10: 1.8 [95% confidence interval 1.3 to 2.3]; p = 0.004.) This adverse effect of anemia on survival was noted in all three presenting clinical syndromes (stable angina, unstable angina, and MI). CONCLUSIONS: Anemia is an independent predictor of mortality after PCI and is associated with higher short-term adverse procedural events.

Aged↗
PubMed2004

Correlation of postpercutaneous coronary intervention creatine kinase-MB and troponin I elevation in predicting mid-term mortality.

Creatine kinase-MB (CK-MB) and troponin I elevations after successful percutaneous coronary intervention (PCI) are common, and different gradations have been correlated with mortality. To establish which of these 2 markers of myonecrosis, CK-MB and troponin I, accurately predicts mortality after successful PCI, we analyzed 2,873 patients without acute myocardial infarction who underwent PCI for in-hospital events and mid-term mortality. Patients were stratified into 4 groups based on peak post-PCI cardiac markers values: group I: normal CK-MB (<16 U/L) or troponin I (<2 ng/ml); group II: CK-MB or troponin I levels 1 to 3 times normal; group III: >3 to 5 times normal; and group IV: >5 times normal. CK-MB elevation occurred in 16.1% of patients, with 12.2%, 2.3%, and 1.6% in groups II to IV, respectively. Troponin I elevation was detected in 38.9% of patients, with 16.4%, 8.4%, and 14.1% in groups II to IV, respectively. There was poor correlation between postprocedural CK-MB and troponin I values (r = 0.10) and in their individual subgroups. Kaplan-Meier estimates of death for postprocedure CK-MB were 2.1%, 2.7%, 1.7%, and 10.3% (p = 0.002) for groups I to IV, respectively; for troponin I, these estimates were 2.2%, 2.3%, 2.9%, and 2.1% for groups I to IV, respectively (p = 0.58). A Cox proportional hazards model showed that CK-MB >5 times normal was the strongest predictor of mortality (hazard ratio 6.7, 95% confidence interval 1.9 to 22.9; p = 0.002), although heart failure, peripheral vascular disease, pre-PCI digoxin therapy, and post-PCI renal failure also predicted mortality. However, neither troponin I peak elevation nor any subgroup predicted mortality. Troponin I is frequently elevated after PCI, but does not predict mortality. Periprocedural CK-MB elevation >5 times normal remains an independent predictor of mid-term mortality and a valuable marker for PCI prognosis in low-to-medium risk patients.

Aged↗