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G Dangas

Publications and source records attributed to G Dangas.

83 records · Page 5Linked to original sources
PubMed1998

Thrombolytic therapy in acute myocardial infarction.

Thrombolytic therapy represents the major advancement for the treatment of acute myocardial infarction (MI) that has been achieved in recent years. Based on the recognition of acute totally occlusive intracoronary thrombosis as the primary cause of ST-elevation MI, thrombolytics were evaluated alone or in combination with antithrombotics for the treatment of acute MI. Streptokinase, APSAC and t-PA were the first "standard" regimens evaluated. The "accelerated" t-PA infusion was introduced as the "gold standard" thrombolytic regimen with the GUSTO trial, and was administered in combination with aspirin and intravenous heparin. Many newer thrombolytics have been developed with the expectation to further decrease acute MI mortality, to decrease bleeding complications or to facilitate drug administration. The introduction of platelet glycoprotein IIb/IIIa inhibitors in clinical pharmacology has added a novel drug category for potential use for primary thrombolysis or in combination with thrombolytics. Conceptualizing thrombolytic and anti-thrombotic combination regimens will optimize treatment of acute MI in the future.

Journal Article↗
PubMed1998

Early Changes in Minimal Luminal Diameter After Balloon Angioplasty and Directional Coronary Atherectomy.

Early elastic recoil has been implicated in the pathophysiology of restenosis after balloon coronary angioplasty (PTCA). Directional atherectomy (DCA) may significantly attenuate this vessel wall reaction by altering the vessel wall architecture, specifically by removing or injuring the medial smooth muscle cells. We compared the magnitude of early changes in minimal lumen diameter (MLD) after DCA followed by adjunctive PTCA (group I) in comparison to PTCA alone (group II). In two groups of 30 lesions, matched for vessel size and location, group I cases showed significantly less recoil than group II cases, as assessed by routinely performed 15 minute post-procedure angiograms: mean changes in post-procedure MLD +0.06mm (increase) vs. -0.31mm (decrease) respectively, p = 0.02. In a histopathologic substudy of the DCA treated patients, those without early recoil had significantly higher incidence of media removal compared to patients with recoil (50% vs. 7%, p = 0.03). Therefore, early changes in MLD, presumably related to elastic recoil, are less with DCA and adjunct PTCA in comparison to PTCA alone. Attenuation of early recoil may be an additional mechanism accounting for the acute lumen gain achieved with this technique.

Journal Article↗
PubMed1997

Angiographic evolution of intracoronary thrombus and dissection following percutaneous transluminal coronary angioplasty (the Thrombolysis and Angioplasty in Unstable Angina [TAUSA] trial).

The evolution and progression of thrombus and dissection after percutaneous transluminal coronary angioplasty (PTCA) are unknown. As part of the protocol of the Thrombolysis and Angioplasty in Unstable Angina (TAUSA) trial, 1 and 15 minutes post-PTCA angiograms were routinely performed and evaluated by the core laboratory for the presence of thrombus and either minor or major dissection. Thrombus was present at 1 minute in 4.4% of culprit lesions. This increased to 16% at 15 minutes (p < 0.005) and was equally seen in patients receiving both urokinase and placebo. Any dissection was noted in 25.2% at 1 minute versus 30.5% at 15 minutes (p < 0.08), and this trend was mainly related to an increase in major dissection with urokinase at 15 minutes versus 1 minute (10.1% vs 5.9%, respectively, p = 0.10). The in-hospital clinical outcome of patients with lesions that did or did not have thrombus or major dissection at 1 and 15 minutes was retrospectively assessed in the placebo group. The presence of either thrombus or major dissection at 1 minute was associated with a subsequent incidence of acute closure of 14% and an incidence of emergency bypass surgery of 11% (p < 0.01 compared with no thrombus or major dissection at 1 minute). The absence of thrombus and major dissection at 15 minutes (n = 173) was associated with no subsequent acute closure or emergency bypass surgery, (p < 0.05 for acute closure vs thrombus or major dissection at 15 minutes). Thrombus evolves progressively over 15 minutes after PTCA in unstable angina, whereas dissection is usually present immediately after PTCA. The absence of thrombus and major dissection at 15 minutes is associated with very low-acute in-hospital complications. Delayed angiograms following standard balloon angioplasty for unstable angina may be predictive of low complications and our study suggests a possible role for their use.

Acute Disease↗
PubMed1997

Correlation of angiographic morphology and clinical presentation in unstable angina.

OBJECTIVES: This study sought to correlate angiographically detected complex lesions and intracoronary thrombus with the severity of clinical presentation in unstable angina (UA). BACKGROUND: Unstable angina is usually related to acute thrombosis superimposed on a disrupted plaque. Complex and thrombotic lesions are more prevalent in UA and have been associated with a worse prognosis. The highest levels of the Braunwald classification of UA (III = rest angina within 48 h of presentation; C = postinfarction angina; and c = angina refractory to maximal medical therapy) can be used to assess the severity of clinical presentation, but they have not been directly correlated with thrombotic and complex lesions. METHODS: We conducted a prospective study of 284 patients with UA who underwent cardiac catheterization. A single angiographer with no knowledge of the clinical classifications interpreted all angiograms. Culprit lesions identified in 200 patients were classified as simple or complex. Complex lesions included the categories complex morphology, intracoronary thrombus (ICT) or total occlusion. Lesions were also quantitatively analyzed, and Thrombolysis in Myocardial Infarction (TIMI) flow was assessed. Univariate and multivariate logistic regression analyses of the angiographic findings were performed controlling for all cardiac risk factors, previous angioplasty or bypass surgery and multivessel disease, and we sequentially compared Braunwald classes III, C and c with classes < III, < C and < c, respectively. RESULTS: Class III was associated with complex lesions (p = 0.04) and decreased TIMI flow (p = 0.03). Class C angina correlated with complex lesions (p = 0.04), ICT (p = 0.005) and decreased TIMI flow (p = 0.03). Class c angina was associated with ICT (p = 0.02). The degree of stenosis by quantitative angiography was not associated with any particular Braunwald class. CONCLUSIONS: Recent rest pain and refractory or postinfarction UA, or both, are strongly associated with the general category of complex lesions and specifically with angiographically detected ICT and decreased TIMI flow.

Aged↗
PubMed1997

A single-step stent delivery, deployment, and expansion system.

Placement of intracoronary stents now comprises a significant number of the percutaneous coronary revascularization procedures being performed in high-volume interventional laboratories in the United States. Stents have become popular because of the reliable acute results, and decreased restenosis. The most common stent currently in use in the United States is the Palmaz-Schatz balloon-expandable stent (PS stent). This stent delivery system (SDS) usually requires predilatation with a balloon and another dilatation, after stent deployment, with a high-pressure balloon in order to adequately expand the stent. We report on a new hybrid stent-delivery system using the PS stent, the sheath from the SDS, and an NC Bandit balloon. This new hybrid system is safe and significantly decreases the procedure time, fluoroscopy time, and need for additional stents due to angiographic dissection resulting from inexact positioning of the high-pressure balloon within the initially deployed stent, and/due to inadequate placement of the first stent. This may be an ideal delivery system for single stent deployment using currently approved FDA equipment.

Angioplasty, Balloon, Coronary↗
PubMed1997

Thrombin Generation and Activity During Coronary Angioplasty: Influence of Angiographic Lesion Morphology.

OBJECTIVE: To investigate the relationships between coronary atherosclerotic plaque injury, lesion morphology, and activation of the coagulation cascade. BACKGROUND: Balloon angioplasty of coronary lesions may result in intracoronary thrombin generation and activity. It is unknown whether the angiographic morphology of the lesion prior to intervention, an indicator of the presence of thrombus in the lesion, is a determinant of the degree of coagulation cascade activation. METHODS AND RESULTS: Biochemical markers of thrombin generation (prothrombin fragment F1+2) and thrombin activity (fibrinopeptide A; FPA) were measured in coronary blood before, 1 and 10 minutes after percutaneous transluminal coronary angioplasty (PTCA) in 24 patients with an angiographically complex lesion morphology and 24 patients with an angiographically simple lesion morphology. Using previously defined criteria, 18 of the 48 patients (38%) demonstrated a significant rise in coronary plasma F1+2; 8 of these 18 (44%) had simple and 10 of 18 (55%) had complex angiographic lesion morphologies (p=NS). With respect to thrombin activity, 15 of the 48 patients (31%) demonstrated a significant rise in coronary plasma FPA; 7 of these 15 patients (47%) had a simple lesion morphology and 8 (53%) had a complex morphology (p=NS). When analyzed as a group, patients with complex lesion morphologies demonstrated a small elevation in coronary plasma levels of FPA 10 minutes post-PTCA (median 3.2 ng/ml, 95% CI 2.4Ð5.8 ng/ml) in comparison to the levels measured proximal to the lesion pre-PTCA (median 2.1 ng/ml, 95% CI 1.6Ð3.5 ng/ml; p=0.05). In contrast, in the group of patients with simple lesion morphologies, the plasma FPA levels proximal to the lesion pre-PTCA (median 2.1 ng/ml, 95% CI 1.5 to 3.9 ng/ml) were similar to those measured 10 minutes after the procedure (median 2.0 ng/ml, 95% CI 1.5 to 6.3 ng/ml; p=NS). CONCLUSIONS: In comparison to patients with angiographically complex lesions, patients with angiographically simple lesions demonstrate a similar incidence (~33%) of elevated coronary plasma thrombin generation (F1+2) and activity (FPA) after PTCA. As a group, patients with angiographically complex lesions (irregular borders, overhanging edges, filling defects) demonstrate a slightly greater increase in thrombin activity in comparison to patients with simple lesion morphologies. Percutaneous coronary interventions of lesions with a wide variety of angiographic morphologies are prone to result in activation of the coagulation cascade.

Journal Article↗
PubMed1996

Use of a pneumatic compression system (FemoStop) as a treatment option for femoral artery pseudoaneurysms after percutaneous cardiac procedures.

Pseudoaneurysm (PA) formation is a well-documented complication of femoral arterial puncture in patients undergoing percutaneous cardiac procedures. Besides surgical repair, there has been success in obliterating the PAs by Duplex ultrasound guided compression (mostly those < 4.0 cm). We analyzed the use of prolonged femoral compression using a pneumatic compression system (FemoStop by USCI) in 10 patients who developed femoral PAs following an interventional cardiac procedure. All PAs were diagnosed by ultrasound and had unsuccessful duplex-guided compression. The size of the PA ranged from 2.8-4.0 cm in diameter. All patients had the FemoStop system placed over the PA with continuous pressure for 12-18 hr. PA obliteration was successful in 90% of cases as confirmed by ultrasound. The only complication observed was skin abrasion in two patients. Our results indicate that the FemoStop system is a simple and effective technique for treatment of femoral artery PAs.

Aged↗
PubMed1996

Management of restenosis after coronary intervention.

Coronary restenosis has proven to be the "Achilles heel" of percutaneous coronary interventions, frequently leading to repeated procedures. The pathogenesis of restenosis can be divided into four phases: early elasic recoil (hours to days), mural thrombus formation (hours to days), neointimal proliferation and extracellular matrix formation (weeks), and chronic geometric arterial changes (months). Restenosis is device nonspecific except for intravascular stents, which can eliminate elastic recoil and prevent geometric vessel changes, leading to decreased restenosis. Of all antithrombotics tried so far, only an inhibitor of the platelet IIb/IIIa integrin, which may lead to early vessel wall passivation, has shown reduction of clinical restenosis. Trapidil (antiproliferative agent) and angiopeptin (somatostatin analog) have also resulted in improved restenosis rates. The field of local drug delivery is currently under investigation in association with radiation or molecular therapy. The current specific target of these approaches is the neointimal proliferation, especially because this is the most dominant mechanism of restenosis after stent placement. Evaluation of these novel methods is complex and interrelates the delivery system with the therapeutic agent administered. However, they provide the means for very specific and timely interruption of the pathogenic process that may lead to better understanding and, ultimately, elimination of restenosis.

Angioplasty, Balloon, Coronary↗
PubMedDate not supplied

Changing concepts in the determination of valvular stenosis.

The cardiovascular system can be characterized as a series of chambers connected by tubes and orifices. The circulatory physiology of this system is governed by hydrodynamic laws. The first application of hydrodynamics to stenotic valve orifices was by Gorlin and Gorlin in 1951, with direct measurement of transvalvular pressure gradients in the catheterization laboratory. The relative imprecision of fluid-filled catheters was corrected by the introduction of high fidelity micromanometric catheters in 1978. Echocardiography, which directly measures blood velocity, currently provides an accurate and widely applied tool for hemodynamic evaluation. Measured changes in blood velocity can derive pressure gradients previously measured by cardiac catheterization. In the clinically important range of determinations, there is excellent correlation between echocardiographic methods and the Gorlin formula for calculating valvular stenosis. Although noninvasive evaluation of heart valve stenosis has become standard, the same physical laws apply as in the 1950s, and practitioners need to be aware of the limitations of the various methods of hemodynamic calculation.

Aortic Valve Stenosis↗