Arkadiusz Derkacz

Renal artery stenosis in patients with resistant hypertension.

The aim of the study was to assess the significance of renal translesional pressure gradients in predicting improvement in resistant hypertension after stenting for moderate renal artery stenosis (RAS). In 37 patients with RAS and resistant hypertension subjected to renal stenting, translesional pressure gradients both at rest and hyperemic were measured using a pressure guidewire. Twenty-four-hour ambulatory blood pressure measurements were performed in all patients on admission and 3 months after the intervention. Angioplasty was successful in all patients, with reduction of artery diameter stenosis from 60 ± 12% to 10 ± 6% (p <0.0001). At 3 months, with maintained hypotensive agents (4.0 ± 1.4 vs 4.0 ± 1.6), significant reductions in systolic blood pressure (SBP) and diastolic blood pressure were noted (-5 and -2 mm Hg, respectively). In multivariate analysis, the mean baseline gradient (MBG) was the only independent predictor of improvement in SBP (regression coefficient 0.292; standard error 0.11; p value 0.014). In the receiver operating characteristic curve analysis, MBG had a larger area under the curve than other parameters, and the MBG >22 mm Hg had the highest sensitivity, specificity, and accuracy (50%, 95%, and 0.74%, respectively) in predicting hypertension improvement after stenting. In patients with MBG >22 mm Hg, SBP decreased by 12 versus 3 mm Hg (p <0.01) in patients with MBG ≤22 mm Hg, whereas diastolic blood pressure in both groups decreased by 3 versus 1 mm Hg, respectively (NS). In conclusion, MBG value of >22 mm Hg provides the highest accuracy in predicting hypertension improvement after stenting for moderate RAS in patients with resistant hypertension.

Plasma asymmetric dimethylarginine predicts restenosis after coronary angioplasty

Introduction Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of endothelial nitric oxide synthase. Asymmetric dimethylarginine may influence the process of restenosis after coronary angioplasty. The aim of the study was to determine if initial plasma ADMA level could predict restenosis after coronary angioplasty and stenting. Material and methods The study group consisted of 60 consecutive patients (10 women and 50 men, average age 58.9 ±10.4 years old), who underwent percutaneous coronary angioplasty with bare metal stenting for stable coronary artery disease. All patients underwent follow-up coronary angiography after a 6-month period. Patients were divided into two groups, one with restenosis (n = 22), and the other one without restenosis (n = 38). In addition to measuring acknowledged restenosis risk factors, plasma ADMA level was measured before initial angiography. Results Asymmetric dimethylarginine plasma level was significantly higher in the group with restenosis than in the group without restenosis (1.94 ±0.94 µmol/l vs. 0.96 ±0.67 µmol/l; p < 0.05). L-arginine/ADMA ratio was also decreased in the group with restenosis, when compared with the group without restenosis (p < 0.05). Multivariate logistic regression revealed that independent restenosis risk factors were characterised by an initially high ADMA level (p < 0.01), advanced age (p < 0.05) and low level of HDL cholesterol (p < 0.05). Conclusions Pre-procedural elevated plasma ADMA level increases the risk of restenosis in patients who underwent coronary angioplasty and stenting with bare metal stents.

Comparison of the renal hyperemic effects of papaverine and dopamine in patients with renal artery stenosis

The purpose of this study was to assess the hyperemic effects of papaverine and dopamine in the renal microcirculation of hypertensive patients with renal artery stenosis (RAS). Although a poor correlation between angiographic lesion assessment and its hemodynamic significance is known, angiography is a major criterion for the decision of renal artery stenting. Assessment of the hyperemic translesional pressure gradient was recently shown to be conducive in identifying patients who may benefit from renal revascularization. The study included 14 patients (mean age, 66xa0±xa011.2xa0years) with resistant hypertension and moderate RAS. Using a pressure-sensing catheter, systolic, diastolic, and mean translesional pressure gradients, and the distal pressure (Pd):aortic pressure (Pa) ratio (Pd/Pa) were analyzed at baseline and after administration of 40xa0mg papaverine and 50xa0μg/kg dopamine. We did not observe significant changes in DG. Dopamine administration resulted in significant changes in systolic and mean translesional pressure gradients and Pd/Pa when compared with baseline (Pxa0<xa0.05 for all). Changes in these parameters were caused by a decrease in systolic Pd in comparison with baseline conditions (119xa0±xa034xa0mm Hg vs. 101xa0mm Hg; Pxa0<xa0.05). Systolic Pd pressure after papaverine (104xa0mm Hg) did not change significantly. Systolic and diastolic Pa values did not differ from baseline after either dopamine or papaverine bolus administration.This study indicates that, compared with papaverine, the intrarenal bolus of dopamine in hypertensive patients with RAS remains a more powerful hyperemic agent.

Subclavian artery stenosis as a cause of acute coronary syndrome in a patient after coronary artery bypass grafting

We described a case of a 74-year-old man who suffered from acute coronary syndrome 7 years after coronary artery bypass grafting. The patient underwent angioplasty of the obtuse marginal branch of the left coronary artery from venous graft access, which did not result in relief of ailments. Only angioplasty of the narrowed subclavian artery caused an improvement in the patients condition. The clinical significance of narrowing within the subclavian artery in patients after the procedure of implanting the left subclavian artery into the coronary artery system was discussed.

Intravascular low-power laser light illumination: a new method in restenosis prevention

The procedure of percutaneous coronary intervention is associated with the 30% risk of restenosis in the dilatated coronary artery. in order to minimize its occurrence we developed the method of intracoronary low power laser irradiation and called it the photoremodling. We developed and constructed at total set-up for the intravascular illumination. It consists of the laser diode connected with a multimode step-index silica fiber 200/270 μm terminated with a special fiber diffuser, which allows to irradiate homogeneously a coronary vessel in the place of dilatation. The diffuser is inserted into the coronary vessel by a modificated angioplasty catheter. Till now PTCA plus photoremodeling procedures have been carried out in 40 patients (28 with stent implantation and 12 with balloon angioplasty). We did not observed any side effects and complications of the procedure. All patients were qualified for 6 months follow-up, which was terminated in 19 cases with a control coronarography. We did not find any case of restenosis in the stent group. In the group of patients after balloon angioplasty restenosis rate was 25%. The new method of treatment is safe. The preliminary results seem to be beneficial especially in the case of stent implantation.

In vitro human atherosclerotic plaque recognition by photosensitizer mono-L-aspartyl chlorin e6 assisted light induced fluorescence (PALIF)

The main aim of the presented experiments was to assess in vitro capabilities of Photosensitizer Assisted Light Induced Fluorescence (PALIF) to recognise different stages of atherosclerosis. Mono-L-asparyl-chlorin e-6 was used as a photosensitising agent and ultraviolet light (440 nm) as an excitation source to obtain spectra map of artery wall. The luminescence spectra were collected and analised. The specimans were histologically examined and classified into three groups: normal artery wall, atherosclerotic noncalcified plaque and calcified plaque. The ratio of green fluorescence (coming from collagen) to red fluorescence (coming from chlorin e6 bonded with lipid reach, noncalcified tissue) gies a chance to distinguish between normal artery or calcified plaque and noncalcified, lipid reach plaque. Further trials must be performed to evaluate in vitro athermoa detection algorithm as a feedback system for photoangioplasty.

Kidney microcirculation response to adenosine stimulation in renal artery stenosis

Abstract The purpose of this study was to assess the vasoconstrictive effects of adenosine in the kidney microcirculation in hypertensive patients with renal artery stenosis (RAS). Twelve patients with resistant hypertension and moderate RAS were selected for the study. In all patients, systolic, diastolic and mean translesional pressure gradients, distal pressure (Pd), aortic pressure (Pa) and Pd/Pa ratio were measured using a pressure guidewire at baseline and after intrarenal bolus administration of 400 μg adenosine. We observed significant changes in mean translesional pressure gradient and systolic Pd after pharmacological stimulation. The results suggest that in hypertensive patients with RAS, vasomotor activity of the kidney microcirculation may be preserved.

In vitro experimental photodynamic diagnosis of artery atherosclerosis

Background: Although there are several methods for atherosclerosis detection available, none of them seems to be accurate enough to identify the vulnerable atheroscleroitc plaque. Photodynamic diagnosis (PDD) and therapy (PDT) -- a new method evaluated for neoplasms treatment is a modern approach to detecting and treating atherosclerosis. Aim: The purpose of this study was to assess in vitro the capability of PDD with use of chlorin e6 to recognize atherosclerotic plaque and its usefulness as a feedback system for photoangioplasty treatment. Methods: 30 specimens of human aorta. The samples were soaked with chlorin e6 and then washed out. The luminescence spectra were then collected. All samples were examined with light microscopy. Results: Tissue fluorescence is seen as green light. We noted a very strong red fluorescence of chlorin e6 originating from lipid reach plaque. We established a quantitative factor which would be the ratio R of chlorin e6 red intensity in its 660 nm maximum compared to the area of green luminescence centered at 515 nm. The highest value of the ratio was reached at atheromatous samples, then calcified and normal ones R2 = 3.51 ± 0.62, R3 = 1.63 ± 0.31, R1 = 1.51 ± 0.15 respectively. Statistically significant difference was noted between group two and one and between group two and three R2 = 3.51 ± 0.62 vs R3 = 1.63 ± 0.31 (p < 0,05); R2 = 3.51 ± 0.62 vs. R1 = 1.51 ± 0.15 (p<0.05) respectively. Conclusions: the following in vitro study confirms that photosensitizer chlorin e6 accumulates within atheromatous plaque. It may be a specific tool for atheromatous and normal or calcified segments discrimination. The advantage of the above method is a possibility of a real time imaging followed by targeted therapy of various forms and stages of atherosclerosis.

Optical device for intravascular low-power laser illumination

The treatment method presented in this paper is an adjunct to coronary angioplasty. It consists in irradiating a previously dilated artery with laser light which stimulates endothelium proliferation and reduces local inflammation. The influence of 808 nm laser light on the endothelium was studied in vitro. Because of the location of atherosclerotic plaques, illumination of the endothelium poses a problem. To overcome it, we have designed and built a laser set-up for homogeneous intravascular illumination in vivo.