1,721,063 research outputs found
Seven-year recurrence of left ventricular apical ballooning
No full textLeft ventricular apical ballooning (Tako-tsubo syndrome) is an acute and rapidly reversible dysfunction of the left ventricle, triggered by a profound psychological stress. We describe an interesting case of very late recurrence
Emergency stenting of totally occluded left main coronary artery in acute myocardial infarction
No full textWe report a case of emergency stenting for acute occlusion of the left main coronary artery in the setting of acute myocardial infarction. Although stent implantation allowed prompt revascularization and successful immediate management of this life-threatening condition, subacute stent thrombosis occurred, requiring re-PTCA followed by surgical revascularization. This case suggests that stenting of an acutely occluded left main coronary artery may be a life-saving procedure but should only be used as a bridge to surgery rather than a definitive treatment modality
Comparison of nifedipine, propranolol and isosorbide dinitrate on angiographic progression and regression of coronary arterial narrowings in angina pectoris
No full textCalcium antagonists and beta blockers may retard or inhibit atherogenesis. This study investigated whether nifedipine or propranolol influences coronary atherosclerosis in humans. In selected patients with effort angina and proven coronary artery disease, the cineangiographic pattern after 2-year therapy with nifedipine (group 1, 39 patients), propranolol (group 2, 36 patients) or isosorbide dinitrate (group 3, 38 patients) was compared to that before treatment. The disease evolved to a different extent in the 3 groups. Patients with evidence of progression of old narrowings and appearance of new narrowings were significantly fewer in group 1 (31% and 10%) than in group 2 (53% and 34%) and group 3 (47% and 29%). The number of stenoses with evidence of progression was significantly smaller after nifedipine (14), and larger after propranolol (39) compared with group 3 (24). Thus, nifedipine seemed more protective than the other 2 drugs against coronary atherosclerosis. The coronary risk factors were normal in the nifedipine group and remained so with treatment, suggesting that they were dissociated from influences on atherosclerosis. The evolution, as judged by the number of narrowings with progression, appeared significantly (p less than 0.01) worse with propranolol than with isosorbide dinitrate. Propranolol caused unfavorable modifications of serum lipids; there was a 28% increase in total triglycerides and a 25% decrease in high density lipoprotein cholesterol at 12 months in group 2
Large coronary aneurysm complicated by acute myocardial infarction: combined intravascular ultrasound imaging and doppler flow assessment before and after PTFE-covered stent implantation
No full textAlthough most patients with coronary artery aneurysms are asymptomatic, manifestations of myocardial ischemia may occur. However, the role that a coronary aneurysm may play in impairing arterial flow of an otherwise normal coronary circulation is not completely known. A 64-year-old woman with previous anteroseptal myocardial infarction was found to have a large aneurysm of the proximal left anterior descending (LAD) coronary artery without angiographic evidence of atherosclerotic disease. IVUS evaluation revealed an 18 mm long and 12.2 x 10.8 mm wide aneurysm without atherosclerosis, thrombus or calcification. Pulsed wave Doppler showed significant reduction of LAD flow reserve, which normalized after successful obliteration of the aneurysm with polytetrafluoroethylene (PTFE)-covered stent implantation. Severe in-stent graft restenosis was found at 7-month angiographic and intravascular ultrasound follow-up, which was managed successfully with minimally invasive direct coronary bypass surgery. The patient did well, without symptoms over the following year
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
[The flow-pressure relationship in coronary perfusion in myocardial hypertrophy in hypertension]
No full textFor any given perfusion pressure the difference between coronary autoregulated and maximally vasodilated flow represents the flow reserve. If hypertension and cardiac hypertrophy are present, the line of autoregulated flow becomes higher, and the pressure-flow relationship at maximal vasodilation less steep, due to the raised resistance. In these circumstances, flow reserve reduces and the point at which rest flow equals maximal achievable flow may be shifted to a higher perfusion pressure. Thus, flow would decline even if the perfusion pressure is lowered to normal. We tested this point in a setting of patients having chest pain and normal angiography of the left epicardial branches. Baseline flow (ml/min) from the great cardiac vein (thermodilution) was 142 +/- 13 in 9 normotensives (controls), 144 +/- 15 in 7 hypertensives (Group 1) with normal (114 +/- 11 g) left ventricular mass index and 188 +/- 17 in 8 hypertensives (Group 2) whose left ventricular mass (171 +/- 24 g) exceeded the mean +2 SD of normal. Coronary perfusion pressure was lowered in these patients by 5 mmHg every 5 minutes with a titrated nitroprusside infusion, taking as endpoints a perfusion pressure of 60 mmHg in the controls and of 70 mmHg in hypertensives. At endpoints, flow was similar to baseline in controls and Group 1. In Group 2 flow started to decline and myocardial oxygen extraction to slightly but significantly rise at perfusion pressure of from 90 to 80 mmHg; at the endpoint flow was reduced by 26% of baseline (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS
[Intravenous ultrasonography as a method for imaging the morphoanatomical effects of coronary angioplasty]
No full textDespite the therapeutic success of percutaneous transluminal coronary angioplasty (PTCA), the mechanisms by which PTCA increase vessel luminal size remain uncertain. To better understand the transmural morphologic changes associated with PTCA of stenosed coronary arteries, we studied with a high-frequency intravascular ultrasound catheter 18 coronary artery segments in 18 patients following balloon angioplasty. High-quality cross-sectional images were obtained from 15 coronary sites without complications in all patients. Two distinctive morphologic features following balloon angioplasty were appreciated by intravascular ultrasound imaging. The first pattern, observed in 10 cases (67%), consisted of a stretched plaque without any evidence of dissection. The second pattern, found in 5 cases (33%), demonstrated a dissection of the plaque ranging from a radial tear with separation of the 2 ends of the plaque to an extensive dissection which, in 1 case, encompassed the entire circumference of the artery. Although angiography showed a good post-angioplasty result in all cases, intravascular ultrasound evidenced a large amount of residual atheroma occupying the artery cross-sectional area. In addition, this imaging modality revealed more often than angiography the presence of calcification and dissection. These data demonstrate that PTCA creates different morphologic patterns which are related to the mechanisms of lumen enlargement and that the coronary artery anatomy after dilatation is much more complex than that observed with angiography. This study confirms that intravascular ultrasound is a feasible and safe imaging modality which provides new valuable insight into the mechanisms by which angioplasty improves vessel patency
Coronary vasomotor and therapeutic influences of propranolol and nifedipine on the spontaneous component of mixed angina
No full textIn 24 patients with spontaneous and effort-related angina (mixed angina), propranolol (80 mg q.i.d.) was significantly more beneficial than nifedipine (20 mg q.i.d.) on the number, duration and severity of the spontaneous manifestations. In some cases nifedipine elicited a paradoxical response. These patterns are unlikely to have resulted from different influences on the myocardial oxygen demands, since heart rate was steady before the occurrence of ischaemia and systemic arterial pressure was equally reduced in all patients. Sublingual nifedipine (10 mg) was tested in 12 patients and the residual lumen diameter of significant (greater than 50%) coronary stenoses (quantitative angiography) was unchanged in one, enhanced in seven and reduced in four of them. Lumen variations ranged from +1.59 to -1.2 mm and correlated closely with the results of oral nifedipine treatment. Propranolol (0.1 mg kg-1 i.v.) was tested in the other 12 cases and in none did variations of stenosis lumen diameter exceed 0.3 mm. These observations indicate that: in a number of lesions a portion of pliable wall may offer a compliant substrate for vasomotor influences; this may be the major factor whereby coronary obstructions cause spontaneous, besides effort-related angina; nifedipine is effective on the former manifestation provided that it does not promote stenosis constriction; propranolol may result in benefit through bradycardia facilitating coronary flow in diastole and reducing the baseline metabolic demands, to elevate the threshold of ischaemia during transient impedance to flow
Clinical use of calcium channel blockers as ventricular unloading agents
No full textCalcium channel blockers relax the arterial smooth vasculature and lower blood pressure when it is elevated because of excessive vasoconstriction. They may be regarded as ventricular unloading agents. Nifedipine (11 cases, Group 1) and verapamil (12 cases, Group 2) were tested in hypertensive patients with cardiac enlargement (LV diastolic diameter greater than or equal to 60 mm), ECG signs of LV strain, lung congestion and dyspnea at rest, in an acute (nifedipine 20 mg; verapamil 160 mg) and 1-month (nifedipine 20 mg q.i.d.; verapamil 160 mg t.i.d.) therapeutic evaluation. In the acute study nifedipine reduced systemic vascular resistance (SVR), mean arterial pressure (MAP), mean pulmonary wedge pressure (PWP) and LV diastolic diameter (DD) and improved cardiac index (CI) and Vcf. In Group 2 verapamil reduced SVR and MAP, improved CI and was not effective on PWP, LV DD and Vcf. Verapamil was discontinued in 2 patients who developed severe dyspnea at rest after 3-4 days of continued oral treatment. At the end of the trial Vcf, PWP and LV DD were unchanged in the remaining subjects in Group 2 despite persistent pressure reduction. In Group 1 all of the patients had relief of dyspnea and lung congestion, reduction of heart size, persistent decrease of MAP and PWP, and improvement in Vcf. The only side effect was ankle edema in 4 cases. A less potent vasodilating action of verapamil and a predominant depression in cardiac contractility may account for the different results with the two drugs, in spite of a shared antihypertensive effect. These findings prove that functional changes in the failing hypertensive heart may differ after nifedipine compared to verapamil as a result of interaction and relative preponderance of influences on afterload and contractility
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