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Biomedical subjects

R Ramadan

Publications and source records attributed to R Ramadan.

17 recordsLinked to original sources
PubMed2003

West Nile meningo-encephalitis infection in a kidney transplant recipient.

West Nile virus is an arbovirus known to cause meningo-encephalitis in immuno-competent as well as in immunocompromised patients. Herein, we describe a kidney transplant recipient in whom meningo-encephalitis infection was caused by the West Nile virus. The clinical presentation was fever, headache, photophobia, confusion, neck stiffness, and positive Kerning test. The patient was treated with IV acyclovir, cefuroxime, ampicillin, and fluids. During hospital stay, the patient did not experience any episode of allograft rejection. Fever resolved and at follow up he was doing well. West Nile virus infection should be considered in immunocompromised patients including transplant recipients with meningo-encephalitis, especially during epidemic outbreaks.

Adult↗
PubMed2001

Retrocaval in situ RIMA for distal marginal arteries grafting.

The length of the in situ right internal mammary artery (RIMA) often restricts its use as a graft to distal marginal arteries. We describe herein a retrocaval supra-azygous extra-pleural passage of the RIMA that allows a significant gain in length. We report our experience in 30 patients with distal marginal lesions or with large hearts.

Humans↗
PubMed2000

Effects of A-192621.1, a specific endothelin-B antagonist, on intrarenal hemodynamic responses to endothelin-1.

The present study examined the effects of A-192621.1, a highly selective endothelin-B- (ETB) receptor antagonist, on the renal hemodynamic and systemic actions of endothelin-1 (ET-1). Intravenous injection of ET-1 (1.0 nmol/kg) into anesthetized rats produced a sustained decrease in renal blood flow (assessed by ultrasonic flowmeter) and a significant increase in renal vascular resistance, as well as an increase in mean arterial pressure. These changes were significantly augmented by pretreatment with A-192621.1 (3.0 mg/kg/h). Analysis of intrarenal blood flow by laser-Doppler flowmeter revealed that ET-1 caused a marked and sustained decrease in cortical blood flow, associated with a transient increase in medullary blood flow. The reduction in cortical blood flow in response to ET-1 was further enhanced by pretreatment with A-192621.1, whereas the ET-1-induced medullary vasodilatation was completely abolished and reversed into a vasoconstrictor response. These findings suggest that the ETB-receptors mediate the systemic and renal vasodilatory actions of ET-1 in the rat, and that their activation may serve as a physiological counterbalance that modulates ET-1-induced vasoconstriction.

Animals↗
PubMed2000

Beneficial effect of HEPES buffer in repeated coronary reperfusion.

BACKGROUND: We have demonstrated previously that, when repeated reperfusion is performed after reocclusion, there is a decrease in the amount of myocardial salvage, despite early reperfusion. Treatment with nisoldipine induced a beneficial effect by reduction of infarct size in this experimental model. OBJECTIVE: To study the effect of HEPES buffer on infarct size, using a repeated-reperfusion model. METHODS: The left anterior descending coronary artery was occluded in anesthetized dogs. Thirty minutes after the occlusion, dogs were allocated randomly to either the treatment group (n = 7; HEPES 0.64 mmol/l infused intravenously throughout the experiment) or the control group (n = 8; saline). Occlusion was maintained for 2 h, followed by 1 h of reperfusion, then 1 h of reocclusion and 2 h of second reperfusion. An in-vivo area at risk was determined by gentian violet staining, and infarct size was defined and quantitated by triphenyl-tetrazolium chloride staining. RESULTS: Hemodynamic measurements were similar in both groups. Mass of necrosis/mass at risk was significantly smaller in the HEPES group (30.7 +/- 1.6%, mean +/- SEM) compared with controls (50.6 +/- 3.8%, P < 0.001). CONCLUSION: Treatment with HEPES induces a beneficial effect by reduction of infarct size in repeated coronary reperfusion.

Analysis of Variance↗
PubMed2000

Mechanisms of big endothelin-1-induced diuresis and natriuresis : role of ET(B) receptors.

Endothelin-1 (ET-1) at high concentrations has marked antidiuretic and antinatriuretic activities, whereas its precursor, big endothelin-1 (big ET-1), has surprisingly potent diuretic and natriuretic actions. The mechanisms underlying the excretory effects of big ET-1 have not been fully elucidated. To explore these mechanisms, we examined the effects of a highly selective ET(B) antagonist (A-192621.1), a calcium channel blocker (verapamil), a nitric oxide synthase inhibitor (N-nitro-L-arginine methyl ester [L-NAME]), and a cyclooxygenase inhibitor (indomethacin) on the systemic and renal actions of big ET-1 in anesthetized rats. An intravenous bolus injection of incremental doses of big ET-1 (0.3, 1. 0, and 3.0 nmol/kg) produced a significant hypertensive effect that was dose dependent and prolonged (from 113+/-7 mm Hg to a maximum of 148+/-6 mm Hg). The administration of big ET-1 induced marked diuretic and natriuretic responses (urinary flow rate increased from 8.5+/-1 to 110+/-14 microL/min, and fractional excretion of sodium increased from 0.38+/-0.13% to 7.51+/-1.24%). Glomerular filtration rate and renal plasma flow significantly decreased only at the highest dose of big ET-1. Pretreatment with A-192621.1 (3 mg/kg plus 3 mg. kg(-1). h(-1)) significantly abolished the diuretic (17+/-5 microL/min to a maximum of 19+/-3 microL/min) and natriuretic (0. 29+/-0.1% to a maximum of 1.93+/-0.37%) responses induced by big ET-1. Moreover, A-192621.1 potentiated the decline in glomerular filtration rate and renal plasma flow and the increase in mean arterial blood pressure produced by the low doses of big ET-1. Similar to A-192621.1, pretreatment with a nitric oxide synthase inhibitor (L-NAME, 10 mg/kg plus 5 mg. kg(-1). h(-1)) significantly and comparably reduced the diuretic and natriuretic actions of big ET-1 and augmented the hypoperfusion/hypofiltration and systemic vasoconstriction induced by high doses of the peptide. Pretreatment with verapamil (2 mg. kg(-1). h(-1)) slightly inhibited the diuretic/natriuretic effects of the high-dose big ET-1 and completely prevented the increase in mean arterial blood pressure provoked by the peptide. Unlike verapamil and L-NAME, only indomethacin administration was associated with significant natriuretic/diuretic responses and did not influence the pressor effect and renal actions of big ET-1. Taken together, these results suggest that big ET-1-induced diuretic and natriuretic responses are mediated mainly by stimulation of nitric oxide production coupled to ET(B) receptor subtype activation.

Animals↗
PubMed1999

Do not resuscitate (DNR): analysis of the DNR act.

Due to advances in technology, physicians and patients are being faced with the issue of do not resuscitate (DNR). DNR is an order that determines whether or not cardiopulmonary resuscitation (CPR) should be administered to a critically ill person. Within the state of Oklahoma, the Oklahoma DNR act was created in order to establish regulations regarding the decision-making of when to use CPR. This Act gives rise to legal and ethical problems, which have been taken into consideration by the Oklahoma Association for Healthcare Ethics (OAHE). The following article focuses on DNR with examples of case histories and possible recommendations for improvement to the current law. Furthermore, this article sets out to show why the decision of whether or not to resuscitate should be made by the patient or their family.

Female↗
PubMed1998

Continuous warm blood cardioplegia pitfalls and solutions.

BACKGROUND: Continuous warm blood cardioplegia offers superior preservation in both routine and complicated cardiac cases. Management of continuous perfusion is an important task during each case. METHODS: The authors have developed several specific techniques to ensure stable catheter insertion and placement for continuous coronary sinus or antegrade ostial perfusion. RESULTS: Over 3,800 patients have been operated on with continuous warm blood cardioplegia using catheter techniques as described in this article. The overall 30-day mortality was 3.9%. CONCLUSIONS: Safe application of continuous warm blood cardioplegia has many advantages over prior cold techniques, but surgeons must know certain technical modifications to be able to universally apply continuous techniques safely.

Blood↗
PubMed1997

Nonpenetrating clips for coronary anastomosis.

BACKGROUND: A nonsuture clip technique (nonpenetrating titanium clips applied to everted tissue edges at high compressive forces) was used to perform coronary anastomoses in a clinical setting. METHODS: Clipped coronary anastomoses were performed in 10 patients. The anastomoses incorporated the left internal mammary artery to the left anterior descending artery (n = 1) and the saphenous vein to the right coronary artery (n = 5), the posterior descending artery (n = 2), the diagonal artery (n = 2), and one vein-to-vein proximal anastomosis (n = 1). RESULTS: The mean duration for completion of the anastomoses was 15 minutes (range, 7 to 20 minutes). This time was reduced from 20 minutes at the beginning of the clinical experience to 7 minutes for the last 3 patients. No technical complication was related to clip application and all patients had uneventful outcomes. Three anastomoses studied by coronary angiography were patent without stenosis. CONCLUSION: The clipped anastomotic technique has a rapid learning curve, the same safety as suture methods, and the potential for facilitating endoscopic vascular reconstructions.

Anastomosis, Surgical↗
PubMed1997

Thoracoscopic internal mammary artery harvesting: technical considerations.

BACKGROUND: Technical details of thoracoscopic harvesting of the internal mammary artery (IMA) are reported. This procedure allows a complete dissection of the left IMA from its origin at the subclavian artery to the sixth intercostal branches with transection of all collateral branches. METHODS: Between September 1995 and September 1996, thoracoscopic harvesting of the left IMA was performed on 32 patients who had undergone a minimally invasive coronary artery bypass grafting procedure. RESULTS: There were no conversions to a standard approach because of an injury to the graft and no reoperations for bleeding. The mean duration of the IMA harvesting procedure was 58.7 minutes (range, 20 to 130 minutes). CONCLUSIONS: This procedure enlarges the field of minimally invasive coronary artery bypass grafting techniques. The thoracoscopic harvest of the full length of the IMA allows the procedure to more closely replicate the open approach.

Endoscopy↗
PubMed1997

Video-assisted coronary bypass surgery: clinical results.

OBJECTIVE: Clinical experience with a video-assisted coronary artery bypass grafting procedure using the internal mammary artery is reported. The technique consists of a videoscopic harvesting of the left internal mammary artery (LIMA) to revascularise the left anterior descending artery (LAD) through a 4-cm left thoracotomy. METHODS: Between September 1995 and July 1996, we performed this procedure on 30 patients (29 males, 1 female; aged 38-71) with an isolated proximal LAD stenosis (n = 21) or occlusion (n = 9). All patients were symptomatic despite appropriate medication. A history of non-transmural myocardial infarction with myocardial viability was found in nine patients. Fourteen patients had a restenosis after previous percutaneous transluminal coronary angioplasty (PTCA). Mean left ventricular ejection fraction was 0.61 (< 0.3 in two patients). The LAD LIMA anastomosis was performed on the beating heart without cardiopulmonary bypass (CPB) in 26 patients. Femoral-femoral CPB was used in three patients because of unstable angina (n = 1) and intramyocardial LAD (n = 2). Conversion to sternotomy and standard CPB was necessary in one patient for extensive endarterectomy of the LAD. RESULTS: There were no operative complications and no reoperations for haemorrhage. Pulmonary infection was observed in one patient and wound infection in one patient. Patients who underwent the complete procedure on the beating heart without conversion or CPB were ready for discharge on the 5th postoperative day (36 h-13 days). Control coronary angiography was performed in 20 patients. In all cases, the graft was patent. In 17 cases, there was a patent graft with no evidence of anastomotic stenosis. An occlusion of the distal segment of the LAD with a retrograde perfusion of the proximal segment and septal branches by the LIMA was found in one case. This patient was symptom-free and the stress test was negative. An anastomotic stenosis was noted in two patients and was treated by angioplasty (n = 1) or conventional surgery (n = 1). CONCLUSION: In conclusion, the efficiency of this minimally invasive approach should be prospectively compared with similar revascularisation with PTCA or surgical approaches using sternotomy with or without CPB.

Angioplasty, Balloon, Coronary↗
PubMed1997

Position-related factors in mitral and tricuspid bioprostheses degenerative changes.

We report clinicopathological findings in 15 patients in whom the same bioprosthesis (BP) had been implanted simultaneously in both mitral and tricuspid positions. The aim of the study was to investigate whether position-related factors played an important role in BP degeneration. There were 14 women and 1 man with a mean age of 34 +/- 11 years. The indications for the initial operation were rheumatic in 14 cases and endocarditis in one patient. The mean interval before reoperation was 7.5 +/- 3.3 years. Predominant cause of reoperation was: structural deterioration of both mitral and tricuspid BPs (6), mitral regurgitation (5), tricuspid BP dysfunction (1), para-aortic leak (1), mitro-aortic thrombi (1). Calcific deposits were the principal cause of early deterioration of mitral BPs and the major cause of late tricuspid BPs dysfunction. This lesion was predominantly related to local factors. Cuspal tears were the principal cause of late (> 9 yrs) mitral BP failure and most probably related to mechanical stress. Extensive fibrosis affected only tricuspid bioprostheses. In 7 patients more extensive degenerative changes occurred in bioprostheses in the mitral rather than the tricuspid position (Group I). However, in the remaining eight the magnitude of the changes was very similar in the two positions (Group II). The interval before reoperation was significantly longer in patients of Group II (9.8 yrs, range 5-13) than patients in Group I (4.9 yrs, range 3-6), (p < 0.01). We concluded that position-related factors exert a major role in bioprosthetic failure. These factors are more deleterious in the mitral position than in the tricuspid position.

Adolescent↗
PubMedDate not supplied

Thoracoscopic IMA takedown.

In recent years, the field of minimally invasive cardiac surgery has grown rapidly beginning with the MIDCAB operation and evolving toward totally endoscopic coronary artery bypass grafting (CABG). It promotes the goal of decreasing surgical trauma while maintaining surgical efficacy. For MIDCAB, a limited anterior thoracotomy or mediastotomy have been proposed to harvest the internal mammary artery (IMA). However, complete graft harvesting of the IMA is difficult under direct vision in these circumstances and may necessitate costal resection and important chest wall retraction. Additionally, it carries the potential risk of kinking or coronary steal syndrome. Thoracoscopic harvesting of the IMA avoids these hazards. It permits complete dissection from the subclavian artery to the sixth inter-costal space (ICS) with section of all collateral branches issuing from the IMA without any traumatic retraction. The technique of IMA takedown described herein has been used regularly by us since 1995. Our current experience shows that it is safe and reproducible after a reasonable period of training. Furthermore, in the objective of performing a totally endoscopic and/or robotic CABG, thoracoscopic IMA takedown would be a prerequisite.

Coronary Artery Bypass↗