Angioplasty and provisional stent treatment of common femoral artery lesions.

Purpose: Isolated atherosclerotic common femoral artery (CFA) disease is a rare cause of symptomatic peripheral arterial disease. Although surgical endarterectomy is considered the therapy of choice, little is known about outcomes of percutaneous treatment.

Materials And Methods: A prospectively maintained single-center database was retrospectively analyzed for outcomes of consecutive patients undergoing isolated percutaneous revascularization of CFA disease between 1996 and 2007.

Endovascular treatment of common femoral artery disease: medium-term outcomes of 360 consecutive procedures.

Objectives: The purpose of this study was to evaluate the technical feasability, safety, and 1-year efficacy of the endovascular treatment of atherosclerotic common femoral artery (CFA) obstructions.

Background: Atherosclerotic CFA obstruction is a known cause of symptomatic peripheral arterial disease. Although surgical endarterectomy is considered the therapy of choice for this condition, little is known about the percutaneous options.

Incidence of atrial fibrillation after percutaneous closure of patent foramen ovale and small atrial septal defects in patients presenting with cryptogenic stroke.

Objective: The occurrence of atrial fibrillation after percutaneous closure of a patent foramen ovale for cryptogenic stroke has been reported in a variable percentage of patients. However, its precise incidence and mechanism are presently unclear and remain to be elucidated.

Design: Prospective follow-up study.

The role of the sizing balloon in selection of the patent foramen ovale closure device size.

Objectives: To find a correlation between the patent foramen ovale (PFO) size measured by the sizing balloon and the appropriate closure device size.

Methods: The PFO of 57 patients was closed using a sizing balloon. A mathematical model was introduced to relate the PFO balloon waist diameter to the closure device size based on the PFO transformation from a slit-like to a circular form during balloon inflation.

Why can pulmonary vein stenoses created by radiofrequency catheter ablation worsen during and after follow-up? A potential explanation.

Background: Radiofrequency catheter ablation of excitation foci inside pulmonary veins (PV) generates stenoses that can become quite severe during or after the follow-up period. Since severe PV stenoses have most often disastrous consequences, it would be important to know the underlying mechanism of this temporal evolution. The present study proposes a potential explanation based on mechanical considerations.

Could increased axial wall stress be responsible for the development of atheroma in the proximal segment of myocardial bridges?

Background: A recent model describing the mechanical interaction between a stenosis and the vessel wall has shown that axial wall stress can considerably increase in the region immediately proximal to the stenosis during the (forward) flow phases, so that abnormal biological processes and wall damages are likely to be induced in that region. Our objective was to examine what this model predicts when applied to myocardial bridges.

Method: The model was adapted to the hemodynamic particularities of myocardial bridges and used to estimate by means of a numerical example the cyclic increase in axial wall stress in the vessel segment proximal to the bridge.

Thresholds and complications with right ventricular septal pacing compared to apical pacing.

Background: Right ventricular septal pacing has been proposed as an alternative to apical pacing. However, data concerning thresholds and requirement for lead repositioning with this technique are scant.

Methods: We reviewed data at implantation and follow-up of 362 consecutive recipients of the same model of active fixation lead (Medtronic 5076-58, Minneapolis, MN, USA) to avoid differences due to lead characteristics.

Utility of the surface ECG before VDD pacemaker implantation.

Background: VDD pacemakers may be implanted in the setting of atrioventricular block with preserved sinus function. Their main advantage over DDD pacemakers is use of a single lead. However, low-amplitude atrial electrograms (EGMs) recorded from the free-floating atrial electrode may lead to undersensing.

An analytical model for the investigation of axial wall forces generated by an arterial stenosis.

The causes of arteriosclerosis are intensively investigated since many decades. While circumferential wall stress has received a lot of attention, axial stress (also called "longitudinal" stress) has been largely neglected, and practically never incriminated. However, it has been suggested in 2003 that moderate and severe arterial stenoses may induce non negligible axial forces cyclically in the vessel segment just proximal to the constriction cone.

Estimation of the axial wall strains induced by an arterial stenosis at peak flow.

In the last 30 years, thousands of basic or clinical studies have been devoted to atherosclerosis or to the problem of restenosis after angioplasty. In these studies, axial stresses in the vessel wall have received practically no attention, contrary to circumferential stress and purely biological aspects. Based on a recent article describing how arterial stenoses can induce a considerable increase in axial wall stress during flow systole in the region immediately proximal to the stenosis entrance, we have used a simple (theoretical) spring model and data available in the literature on the mechanical properties of arteries to investigate the relative wall elongations (axial strains) resulting from the systolic increases in axial stress generated by the stenosis.

Prospective study of axillary vein puncture with or without contrast venography for pacemaker and defibrillator lead implantation.

Axillary vein puncture may be used to implant pacemaker (PM) or cardioverter defibrillator leads, though usually requires venography. We prospectively compared punctures guided by venography versus a new radiological landmark. In 232 patients, the puncture was guided by injecting diluted contrast material via an ipsilateral peripheral vein (group A, n = 142), or without venography using the intersection of the lateral borders of the second and third rib as a radiological landmark, followed by contrast injection in case of failure (group B, n = 90).

Residual stenosis poststenting and subsequent decrease in the proximal reference diameter are correlated: excessive axial wall stress is a plausible explanation.

Purpose: To test the hypothesis that edge restenosis in stented lesions might be due to an increase in axial wall stress in the adjacent proximal vessel segment by examining whether the proximal reference diameters of conventionally stented lesions are reduced at follow-up and whether this reduction depends on the degree of residual stenosis poststenting.

Methods: The literature published in the past 5 years dealing with restenosis following implantation of standard stents was screened for the availability of (1) reference vessel diameters poststenting, (2) mean residual stenosis poststenting, and (3) mean reference vessel diameters at follow-up in the same patients or groups of patients. Data collected from 11 publications were pooled and used to compute the change in reference segment diameter over time.

Thoracic aortic plaques, transoesophageal echocardiography and coronary artery disease.

Background: The purpose of this study was to assess whether the detection of atherosclerotic aortic plaques by transoesophageal echocardiography (TEE) could be used as a marker of coronary artery disease (CAD), relying on their number, cross-sectional surface, depth and localisation.

Methods: The thoracic aortas of 102 consecutive patients (77 men, mean age 67 +/- 12 years) undergoing elective cardiac surgery were assessed by TEE. Atherosclerotic plaques were defined as > or = 5 mm thick focal hyperechogenic zones of the aortic intima and/or lumen irregularities with mobile structures or ulcerations.

[Study of left ventricular function at rest and post-exercise with thallium-201 myocardial scintigraphy synchronized with ECG].

ECG-gated Thallium 201 myocardial scintigraphy provides a simultaneous evaluation of left ventricular perfusion and function. The aims of this study were to determine the changes in left ventricular ejection fraction (LVEF) after exercise and at rest 4 hours after exercise and to compare the results with changes in myocardial perfusion and the severity of the coronary artery disease. Sixty-four men with myocardial ischaemia on scintigraphy who had undergone coronary angiography showing significant lesions within 3 months, were compared with 38 normal men.

A morphological-mechanical explanation of edge restenosis in lesions treated with vascular brachytherapy.

Purpose: Edge restenosis in stenotic lesions treated by implantation of a conventional stent followed (or preceded) by a catheter-based brachytherapy is often attributed to "geographic miss" (GM). We propose a complementary (or, possibly, alternative) explanation based on the concept that a clear postprocedural mismatch between the in-stent lumen and the normal (undilated) lumens of the proximal and/or distal vessel segments results in an excessive, damageable increase of axial wall stress in these segments.

Methods: The possible poststenting situations at both margins of a stent are examined, and based on the presence or absence of an increase in axial wall stress, predictions are made about the lesion evolution.

In-hospital complications of percutaneous intraaortic balloon counterpulsation.

Complications related to intraaortic balloon counterpulsation pumping (IABP) remain a problem despite the development of small caliber balloon catheter shafts and introducer sheaths. The authors report their experience in counterpulsation-related complications of 201 consecutive patients who underwent 212 percutaneous counterpulsation balloon insertions from June 1989 to June 1996 by use of balloons with 8-9.5 French shafts.

[Prognostic value of thallium 201 myocardial scintigraphy with dipyridamole before peripheral arterial surgery].

The evaluation of patients who are candidates for peripheral arterial surgery is difficult. The aim of this study was to show that dipyridamole stress scintigraphy could be a prognostic aid for patient selection. Between 1991 and 2000, 275 patients underwent dipyridamole stress myocardial scintigraphy before peripheral arterial surgery of the lower limbs (49%), the aortic (33%) or carotid arteries (18%).

Is axial wall stress compressive in certain arteries?

In mathematical-physical models of blood vessels, the "zero-stress state" of the vessel wall is usually defined with reference to the atmospheric pressure (pa approximately 750 mmHg = 100 kPa). Due to this conventional choice, axial and circumferential stresses generated by the (positive) transmural pressure over the radial wall depth can only be positive (in absence of residual stresses) and thus, by definition, only tensile. If the zero-stress state were defined "unconventionally" with reference to vacuum pressure (= 0 mm Hg), the isotropic compressive stress--pa generated by the atmospheric pressure everywhere in the wall would, however, be included in the stress values, and negative (= compressive) stresses would become formally possible.

The effect of image distortion on 3-D reconstruction of coronary bypass grafts from angiographic views.

Three-dimensional (3-D) reconstructions of coronary bypass grafts performed from X-ray angiographic images may become increasingly important for the investigation of damaging mechanical stresses imposed to these vessels by the cyclic movement of the heart. Contrary to what we had experienced with coronary arteries, appreciable reconstruction artifacts frequently occur with grafts. In order to verify the hypothesis that those are caused by distortions present in the angiographic images (acquired with image intensifiers), we have implemented a grid correction technique in our 3-D reconstruction method and studied its efficiency with phantom experiments.

Altered expression of proteins of metabolic regulation during remodeling of the left ventricle after myocardial infarction.

Non-infarcted myocardium after coronary occlusion undergoes progressive morphological and functional changes. The purpose of this study was to determine whether non-infarcted myocardium exhibits (1) alteration of the substrate pattern of myocardial metabolism and (2) concomitant changes in the expression of regulatory proteins of glucose and fatty acid metabolism. Myocardial infarction was induced in rats by ligation of the left coronary artery.

In-vivo measurements of wall shear stress in human coronary arteries.

Background: Wall shear stress (WSS) is closely associated with arteriosclerosis. WSS values for various vessels and species are available, but fully in-vivo measurements in human coronary arteries have not yet been reported.

Objective: To measure WSS in undiseased coronary arteries of adult patients at rest.

[Early percutaneous coronary angioplasty in unstable angina].

The risks of complications of percutaneous transluminal coronary angioplasty (PTCA) are increased in unstable angina. Medical treatment for a few days before PTCA is widely adopted to reduce the risk of thrombosis or occlusive dissection during and after the procedure. Over the last few years, the authors have adopted a strategy of early coronary angiography completed by immediate angioplasty when possible, without waiting for the eventual benefit of aspirin or heparin therapy.

Is the indicator dilution theory really the adequate base of many blood flow measurement techniques?

The indicator dilution theory is the underlying model of many blood flow measurement techniques used daily in hospitals, for instance in cardiac catheterization laboratories. The basic version of this theory applies to a "stationary" flow system with one inlet and one outlet, into which a small amount M of indicator is injected "suddenly" at time t = 0 at the inlet. The quintessence of the theory consists in three equations, which themselves result from some apparently simple assumptions about the considered flow systems.

Towards a gold standard for quantitative coronary arteriography.

Densitometric quantification of coronary artery stenoses in angiographic images can be problematic for two reasons: (i) the x-rays are inadequately oriented with respect to the vessel segments of interest at image acquisition; (ii) non-linear effects due for instance to beam hardening, scattered radiation and veiling glare may reduce the accuracy. As a consequence, appreciable discrepancies between degrees of stenosis measured in two different projections can occur. To overcome these limitations, we have designed and tested a combined correction that compensates (at subsequent analysis) for the error contributions due to the cited sources.

A new technique for improved densitometric quantification of coronary artery stenoses in angiographic images.

In vitro studies have demonstrated that densitometric quantification of coronary artery stenoses is superior to geometric methods to assess non-circular lumens. However, in patients, several authors have reported significant discrepancies between area reduction percentages obtained densitometrically from two different imaging projections. Some of the factors causing the discrepancies can be reduced by simple precautions taken during image acquisition.