Catheterization and cardiovascular diagnosis最新文献

The mechanical properties of metal stents are important parameters in the consideration of stent design, matched to resist arterial recoil and vascular spasm. The purpose of this study was to develop a system for a standardized quantitative evaluation of the mechanical characteristics of various coronary stents. Several types of stents were compressed by external hydrostatic pressure. The stent diameter was assessed by placing a pair of small ultrasonic sono-crystals on the stent. From pressure-strain diagrams the ultimate strength and radial stiffness for each stent were determined. For all stents, except the MICRO-II and the Wiktor stent, the diameter decreased homogeneously until an ultimate compressive strength was exceeded, causing an abrupt collapse. Expanded to 3 mm, the mechanical behavior of the beStent, the Crown and the Palmaz-Schatz stent (PS153-series) were comparable. The spiral articulated Palmaz-Schatz stent showed twice the strength (1.26 atm) of the PS-153 (0.65 atm). The NIR stent yielded a maximum strength of 1.05 atm. The MICRO-II and the Wiktor stent did not collapse abruptly but rather showed a continuous decline of diameter with increasing external pressure. The Cardiocoil stent behaved in a fully elastic manner and showed the largest radial stiffness. Difference in mechanical properties between stents were documented using a new device specifically developed for that purpose. These mechanical stent parameters may have important clinical implications.

This report describes a 4-yr-old with critical coronary artery stenosis acquired after surgery for congenital heart disease. The patient was treated successfully with coronary stenting after unsuccessful angioplasty.

Delivery of a balloon-expandable stent was complicated by a systemic embolisation. The radio-opaque stent was lost in the descending aorta, but then removed by using a loop basket intravascular retriever set without any peripheral arterial complication.

Hemodynamic assessment of patients with prosthetic valves can be challenging. Noninvasive techniques may be limited by interference from the prosthetic material, whereas access to the left ventricle for direct pressure measurements often is not possible using common methods. The technique of direct, percutaneous left ventricular puncture has been proven to be a safe method that often provides needed data to help manage difficult clinical situations. We report our 8-yr experience with this technique for assessment of patients with valvular prostheses. Direct left ventricular puncture is a safe technique in patients with prior cardiac surgery and provided significant diagnostic information in the set of patients with multiple valvular prostheses.

We present the case of a calcified right coronary artery lesion with a 90-degree exit angle. Attempts at rotational atherectomy led to wire transection and vessel wall perforation necessitating emergent pericardiocentesis and bypass surgery. We review the literature on complications of rotational atherectomy and the management of coronary perforations and retained guidewire fragments.

The 4-week outcome following Micro stent implantation for acute myocardial infarction was assessed with the use of two different antithrombotic regimens. The patients were postprocedurally treated with acetyl salicylic acid (ASA) and heparin for 24-48 h (Group I; n = 52), or ASA and ticlopidine plus abciximab if indicated (Group II; n = 52). Stent implantation was successful in 49 patients (94%) of group I and in 46 patients (89%) of group II (NS). Subacute stent thrombosis occurred in nine patients (17%) of group I and in 1 patient (2%) of group II (P < 0.05). There were no significant differences in the rates of mortality, coronary bypass operation, or vascular complications. Micro stent implantation in acute myocardial infarction is highly effective and associated with a low risk for subacute stent thrombosis if the patients are postprocedurally treated with ASA and ticlopidine plus abciximab if indicated.

The Prima laser guidewire system (Spectranectics Corp., Colorado Springs, CO) consists of an 0.018" hypotube containing a bundle of 45-microm optical fibers coupled to a pulsed excimer laser operating at a tip fluence of 60 ml/mm2 and a repetition rate ranging from 25-40 Hz. This laser guidewire was specifically designed to cross total occlusions refractory to passage with conventional wires. The Prima wire was evaluated in a feasibility study at 15 U.S. centers. Following failure to cross a total occlusion with approved guidewires, the Prima wire was utilized in 179 patients. Average age of subjects was 61 yr. Lesion locations included left anterior descending (36%), right (45%), and circumflex (19%) coronary arteries. Mean angiographic age of total occlusions was 70 wk (range, 2-1,020 wk, median, 14 wk). The use of the Prima wire either solely or in combination with conventional guidewires resulted in successful crossing in 61% of these previously impenetrable occlusions. Failure of the device was commonly related to length of the occlusion and tortuosity along the occluded pathway. Major complications included myocardial infarction in 7 patients (3.9%), tamponade in 3 (1.7%), and death in 2 (1.1%). This "learning phase" pilot study confirmed the feasibility of a laser guidewire in chronic total occlusions that are resistant to passage of conventional guidewires. An extended registry at these investigative sites is planned.

A 30-mo-old girl developed occlusion of her left anterior descending coronary artery following mitral valve replacement. She presented with refractory angina pectoris. Successful percutaneous transluminal coronary angioplasty of the left anterior descending artery was performed, resulting in restoration of flow, resolution of anginal symptoms, and early improvement in left ventricular function.

We compared the angiographic and clinical outcomes after directional coronary atherectomy (DCA, 13 patients) with those after conventional balloon angioplasty (BA, 21 patients) in patients with protected left main coronary artery stenosis. The initial success rate was 100% in the DCA group and 81% (17 of 21) in the BA group. Restenosis was present in 2 of 11 patients in the DCA group and 9 of 16 patients in the BA group (18% vs. 56%, P < 0.05). DCA and BA improved a minimal lumen diameter. The initial gain after DCA was greater than that after BA. At follow-up, the minimal lumen diameter was larger and the percentage diameter stenosis was smaller in the DCA group than in the BA group. The late loss and loss index were equivalent in both groups. Compared with conventional BA, DCA in protected left main coronary artery stenosis is associated with a higher angiographic success rate and provides a wider luminal diameter with reduced incidence of restenosis.