Biomedical subjects

J R Parga

Publications and source records attributed to J R Parga.

6 recordsLinked to original sources

PubMed2005

Compensatory enlargement of human coronary arteries identified by magnetic resonance imaging.

The aim of the present study was to evaluate the role of magnetic resonance imaging (MRI) for the non-invasive detection of coronary abnormalities and specifically the remodeling process in patients with coronary artery disease (CAD). MRI was performed in 10 control healthy subjects and 26 patients with angiographically proven CAD of the right coronary (RCA) or left anterior descending (LAD) artery; 23 patients were within two months of acute coronary syndromes, and 3 had stable angina with a positive test for ischemia. Wall thickness (WT), vessel wall area (VWA), total vessel area (TVA), and luminal area (LA) were measured. There were significant increases in WT (mean +/- SEM, RCA: 2.62 +/- 0.75 vs 0.53 +/- 0.15 mm; LAD: 2.21 +/- 0.69 vs 0.62 +/- 0.24 mm) and in VWA (RCA: 30.96 +/- 17.57 vs 2.1 +/- 1.2 mm(2); LAD: 19.53 +/- 7.25 vs 3.6 +/- 2.0 mm(2)) patients compared to controls (P < 0.001 for each variable). TVA values were also greater in patients compared to controls (RCA: 44.56 +/- 21.87 vs 12.3 +/- 4.2 mm(2); LAD: 31.89 +/- 11.31 vs 17.0 +/- 6.2 mm(2); P < 0.001). In contrast, the LA did not differ between patients and controls for RCA or LAD. When the LA was adjusted for vessel size using the LA/TVA ratio, a significant difference was found: 0.33 +/- 0.16 in patients vs 0.82 +/- 0.09 in controls (RCA) and 0.38 +/- 0.13 vs 0.78 +/- 0.06 (LAD) (P < 0.001). As opposed to normal controls, positive remodeling was present in all patients with CAD, as indicated by larger VWA. We conclude that MRI detected vessel wall abnormalities and was an effective tool for the noninvasive evaluation of the atherosclerotic process and coronary vessel wall modifications, including positive remodeling that frequently occurs in patients with acute coronary syndromes.

Adult↗

PubMed2004

Case report: MRI evaluation of congenital coronary artery fistulae.

Congenital coronary artery fistula is a rare disease and MRI is a promising technique that may be useful to demonstrate the coronary artery tree. We report three patients who underwent cardiac MRI to investigate right coronary artery fistulae. On clinical examination, a continuous murmur was heard along the left sternal border, and chest X-ray showed moderate cardiomegaly with enlargement of right chambers in all patients. Transthoracic Doppler echocardiography showed fistulae in two cases; the third case was not demonstrated by transthoracic or transoesophageal echocardiography. MRI demonstrated the course of the fistulous vessels in all patients. All patients underwent surgical closure of their coronary artery fistulae. MRI may show detailed anatomy of congenital coronary artery fistulae and may be useful as an additional non-invasive method in their investigation.

Adult↗

PubMed2003

Destruction of cyanide waste solutions using chlorine dioxide, ozone and titania sol.

Increasingly, there are severe environmental controls in the mining industry. Because of lack of technological advances, waste management practices are severely limited. Most of the wastes in the milling industrial effluents are known to contain cyanides and it is recognized that after extraction and recovery of precious metals, substantial amounts of cyanide are delivered to tailings ponds. The toxicity of cyanide creates serious environmental problems. In this paper we describe several methods for the treatment of cyanide solutions. These include: (1) cyanide destruction by oxidation with chlorine dioxide (ClO(2)) in a Gas-Sparged Hydrocyclone (GSH) reactor; (2) destruction of cyanide by ozone (O(3)) using a stirred batch reactor, and finally, (3) the photolysis of cyanide with UV light in presence of titania sol. In all cases excellent performance were observed as measured by the extent and of the destruction.

Chlorine Compounds↗

PubMed2001

Electrocoagulation (EC)--science and applications.

Although electrocoagulation is an evolving technology that is being effectively applied today for wastewater treatment, the paucity of scientific understanding of the complex chemical and physical processes involved is limiting future design and hindering progress. The objective of this review through a survey of the literature is to bring the chemistry and physical processes involved into perspective and to focus attention on those areas critically needing research.

Chemical Phenomena↗

PubMed2001

Partial left ventriculectomy in severe idiopathic dilated cardiomyopathy: assessment of short-term results and their impact on late survival by magnetic resonance imaging.

We evaluated short-term effects of partial ventriculectomy on left ventricular (LV) parameters and its impact on late survival by magnetic resonance imaging (MRI). Twenty patients and 10 normal volunteers were studied, and LV volumes (EDV, ESV), ejection fraction (EF), short- and long-axis dimensions (SA, LA), wall thickness (Wth), shape (LA/SA), geometry (Wth/SA), a geometry index (Phi), and wall-motion score index (WMSI) were evaluated pre- and postoperatively. Also, we compared results and survival of patients with preoperative EF 17%. Short-term results showed significant changes (P < 0.001) in: EF (17.3 +/- 7.3% vs. 30.4 +/- 9.5%), EDV (391.9 +/- 118 vs. 272.7 +/- 90 mL); ESV (308.2 +/- 102.8 vs. 190.3 +/- 68.4 mL); SA (80.5 +/- 10.4 vs. 71.7 +/- 7.8 mm); LA/SA (1.13 +/- 0.1 vs. 1.34 +/- 0.1); Wth (8.35 +/- 0.99 vs. 9.75 +/- 1.41 mm); Wth/SA (0.10 +/- 0.01 vs. 0.14 +/- 0.02), diastolic( 0.80 +/- 0.16 vs. 0.58 +/- 0.13) and systolic (0.78 +/- 0.18 vs. 0.55 +/- 0.12) Phi; and WMSI (-2 vs. -1) (P = 0.032). The EF division showed differences in: LA/SA (1.26 +/- 0.10 vs. 1.49 +/- 0.12) (P < 0.001); Wth/SA (0.13 +/- 0.02 vs. 0.15 +/- 0.02) (P = 0.023); diastolic (0.65 +/- 0.11 vs. 0.48 +/- 0.11) and systolic (0.63 +/- 0.09 vs. 0.46 +/- 0.09) Phi (P < 0.001); and WMSI (-2 vs. -1) (P = 0.033). Finally, correlation between pre/postoperative EF showed for EF < 17%, r = 0.32 and for EF >17%, r = 0.83, which had different late survival. Our study showed significant changes on LV parameters after ventriculectomy. Patients with EF >17% showed better EF correlation between pre/postoperative values and higher survival rate. J. Magn. Reson. Imaging 2001;13:781-786.

Adult↗

PubMed1998

Partial left ventriculectomy with mitral valve preservation in the treatment of patients with dilated cardiomyopathy.

OBJECTIVE: This study reports initial results of partial left ventriculectomy performed with preservation of the mitral valve in the treatment of 27 patients with idiopathic dilated cardiomyopathy. METHODS: Patients were in New York Heart Association class III or IV. Partial ventriculectomy was performed as an isolated procedure in four patients and associated with mitral annuloplasty in 23 patients. There were four hospital deaths (14.8%) and the remaining patients were followed for 11.2 +/- 6 months. RESULTS: Decrease of left ventricular diastolic diameter (81.8 +/- 8.7 to 68.5 +/- 7.6 mm, p < 0.001) and improvement of left ventricular wall shortening (12% +/- 3.1% to 18.1% +/- 3.9%, p < 0.001) were demonstrated by echocardiography after the operation. Left ventricular radioisotopic angiography showed reduction of diastolic volume (495 +/- 124 ml to 352 +/- 108 ml, p < 0.001) and increase of ejection fraction (17.7% +/- 4.6% to 23.7% +/- 8.8%, p < 0.001). Right-sided heart catheterization demonstrated improvement of stroke index (24.3 +/- 7.7 ml/m2 to 28.3 +/- 7.6 ml/m2, p < 0.01) and decrease of pulmonary wedge pressure (23.2 +/- 8.8 mm Hg to 17 +/- 7 mm Hg, p < 0.01). Similar results were documented at 6 and 12 months of follow-up. Functional class improved from 3.6 +/- 0.5 to 1.4 +/- 0.6 (p < 0.001). However, seven patients died at midterm follow-up because of heart failure progression or arrhythmia-related events, and survival rate was 59.2% +/- 9.4% from 6 to 24 months of follow-up. CONCLUSIONS: Partial left ventriculectomy performed with preservation of the mitral valve improves left ventricular function and congestive heart failure in patients with dilated cardiomyopathy. Nevertheless, the high incidences of heart failure progression and arrhythmia-related deaths observed after this procedure preclude its wide clinical application.

Cardiomyopathy, Dilated↗