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Biomedical subjects

M Amrani

Publications and source records attributed to M Amrani.

At least 37 records · Page 2Linked to original sources

Does routine use of the radial artery increase complexity or morbidity of coronary bypass surgery?

BACKGROUND: Despite increasing data supporting its use, the uptake of radial artery coronary bypass grafting by most surgeons remains low. This may partly be from perceptions that it increases risk or complexity of coronary surgery. METHODS: Data on 151 patients who had radial grafts are compared with 179 concurrent nonrandomized controls that underwent conventional surgery using saphenous vein. Additionally, telephone interviews were conducted on 127 radial recipients to assess subjective outcome. RESULTS: Cardiopulmonary bypass and cross-clamp times were similar in both groups (72 versus 74 minutes and 20 versus 22 minutes). Morbidity was comparable (mortality 1% versus 2%; cerebral vascular accident 1% versus 2%; sternal infection 1% versus 2%; resternotomy 4% versus 6%). Of 127 patients contacted, 41 (32%) reported that they had experienced parasthesia, and 65 (51%) reported numbness related to radial harvest; of these, 75% reported their symptoms as resolved or resolving. Early angiography performed in 36 patients revealed a radial patency rate of 92%. CONCLUSIONS: Concerns about increased morbidity and mortality should not hinder adoption of radial artery grafting.

Aged↗

Electron beam tomography for cusp calcification in homograft versus Freestyle xenografts.

BACKGROUND: We have previously shown, by means of electron beam tomography, the pattern of calcification of the aortic root wall of homografts and porcine xenografts after aortic root replacement. However, application of similar methods for cusp calcification raises specific problems that have not been addressed before. METHODS: A new method for localizing and quantifying calcification of the aortic valve cusps has been evolved. Intravenous contrast-enhanced electron beam tomography was introduced to visualize the aortic cusps. This technique was applied to quantify cusp calcification in 37 patients after aortic root replacement with a homograft (group H) or a Medtronic Freestyle valve (group F) at set intervals between 6 months and 2 years. A calcification score in Hounsfield units (HU) and a calcified volume score in cubic millimeters were calculated. RESULTS: The aortic leaflets were clearly visualized in all patients. The mean calcium score in the cusps was 28.8+/-64.4 HU in group F and 62.4+/-66.9 HU in group H (p = not significant). The mean calcified volume score was 327.0+/-425.9 mm3 in group F and 642.0+/-443.0 mm3 in group H (p = not significant). CONCLUSIONS: Contrast enhancement electron beam tomography is a useful tool for quantification of calcium in the aortic valve leaflets. Our preliminary results show a tendency toward more calcification in the homografts. This needs to be studied further in a bigger cohort of patients followed up for longer periods.

Adult↗

Outcome of non-elective coronary artery bypass grafting without cardio-pulmonary bypass.

OBJECTIVES: There is limited experience in the use of beating heart coronary artery bypass grafting (CABG) in emergency and urgent cases. The aim of this study was to retrospectively assess the safety and efficacy of this technique when used in a non-elective setting. METHODS: We retrospectively reviewed all urgent and emergency cases of coronary artery bypass grafting performed without cardiopulmonary bypass (CPB) from July 1999 to February 2000. There were 35 patients in total. The mean age was 64.8+/-11.9. Twenty-six (74.3%) patients had Canadian Cardiovascular Society grade 4 angina. Twenty-six patients (74.3%) had triple vessel disease. Eleven patients (31.4%) were on preoperative IV nitrates and nine patients (25.7%) had a preoperative IABP (intra aortic balloon pump). Three patients (8.6%) had suffered a preoperative cardiac arrest during coronary angiography. Other associated significant risk factors were smoking (60%), hypertension (40%), hypercholesterolemia (57.1%) and previous Q wave myocardial infarction (31.4%). RESULTS: Twenty-two patients (62.9%) were classified as being urgent and 13 patients (37.1%) were classified as emergencies. The mean number of anastomoses performed were 2.8+/-0.8 (range 1-4) with 68.6% of patients under going triple or quadruple vessel grafting. All patients (100%) received at least one arterial graft. There was no conversion to cardiopulmonary bypass. The main postoperative complications were--supraventricular arrhythmias eight (22.9%), low cardiac output seven (20%) and postoperative HF/dialysis two (5.7%). The median postoperative intensive care unit (ICU) stay was 27.5 h. The mean postoperative hospital stay was 8.3+/-3.1 days. One patient died (2.9%) at the eighth day after surgery due to postoperative myocardial infarction, multi-organ failure secondary to the septicaemia and ventricular arrest. CONCLUSION: Non-elective CABG without CPB is feasible and safe with modern cardiac stabilization devices.

Adult↗

Pyruvate/dichloroacetate supply during reperfusion accelerates recovery of cardiac energetics and improves mechanical function following cardioplegic arrest.

OBJECTIVES: Cardioplegic arrest during cardiac surgery induces severe abnormalities of the pyruvate metabolism, which may affect functional recovery of the heart. We aimed to evaluate the effect of pyruvate and dichloroacetate administration during reperfusion on recovery of mechanical function and energy metabolism in the heart subjected to prolonged cardioplegic arrest. METHODS: Four groups of rat hearts perfused in working mode were subjected to cardioplegic arrest (St. Thomas' No. 1), 4 h of ischaemia at 8 degrees C and reperfusion with either Krebs buffer alone (C) or with 2.8 mM pyruvate (P), with 1 mM dichloroacetate (D), or with a combination of both (PD). Mechanical function was recorded before cardioplegic arrest and at the end of experiments. In groups C and PD, additional experiments were performed using (31)P nuclear magnetic resonance spectroscopy in non-working Langendorff mode to evaluate cardiac high-energy phosphate concentration changes throughout the experiment. RESULTS: Improved recovery of cardiac output (% of the preischaemic value+/-SEM, n=9-12) was observed in all three treated groups (65.7+/-4.3, 59.5+/-5.2 and 59.5+/-5.3% in PD, P and D, respectively) as compared with C (42.2+/-4.6%; P<0.05). Recovery of coronary flow was improved from 66.4+/-3.8 in C to 94.9+/-8.6% in PD (P<0.05). The phosphocreatine recovery rate in the first minutes of reperfusion was increased from 9.9+/-1.5 in C to 31.5+/-4.3 micromol/min per g dry wt in PD (P<0.001). No differences were observed in ATP or phosphocreatine concentrations at the end of experiment. CONCLUSIONS: The administration of pyruvate and dichloroacetate improves the recovery of mechanical function following hypothermic ischaemia. Accelerated restoration of the energy equilibrium in the initial phase of reperfusion may underlie the metabolic mechanism of this effect.

Adenosine Triphosphate↗

The clinical outcome of off-pump coronary artery bypass surgery in the elderly patients.

OBJECTIVE: There has been a body of evidence showing that off-pump coronary artery bypass (OPCAB) may reduce morbidity and mortality in the elderly patients. We reviewed our experience, retrospectively, on elderly patients aged 75 years and older who were operated on using the OPCAB technique. We compared their outcome to a similar group of elderly patients who were operated on using conventional coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB) during the same period of time. METHODS: Registry data and patients' notes and charts were reviewed for 56 consecutive elderly OPCAB patients (age 78.5+/-3.5 years) and 87 consecutive CPB patients (age 77.2+/-2.4 years, P=0.01). Both groups had similar risk factor profiles: Parsonnet score 17.4+/-4.4 (OPCAB) versus 16.6+/-5.2 (CPB), P=0.19. We studied in detail their preoperative and postoperative data in order to compare the outcomes of both techniques. RESULTS: The length of stay in the intensive therapy unit (ITU) was 35.4+/-52.9h for OPCAB patients and 77.6+/-144.9h for CPB patients (P=0.0008). No patient died within 30 days in the OPCAB group, whilst ten (11%) CPB patients (P=0.0066) died within 30 days. The incidence of serious complications (including pulmonary oedema, septicaemia, permanent stroke and renal dysfunction requiring haemofiltration or haemodialysis) was one (2%) in the OPCAB group and 11 (13%) in the CPB group (P=0.028). CPB patients required a significantly higher number ten (12%) of intra-aortic balloon pumps (IABP) inserted compared to only one patient (2%) in the OPCAB group who required IABP insertion (P=0.05). Nine (11%) CPB patients were re-operated on for bleeding compared to no OPCAB patient (0%) needing re-operation, P=0.011. CONCLUSIONS: Although the mean age of the OPCAB group was significantly higher than the CPB group, the OPCAB group showed a significant reduction in postoperative serious morbidity, ITU stay and mortality. We believe that such a conclusion may have some effect on the decision-making and cost-effectiveness when performing coronary bypass surgery on the elderly population.

Age Factors↗

Subjective patient outcomes following coronary artery bypass using the radial artery: results of a cross-sectional survey of harvest site complications and quality of life.

OBJECTIVES: To assess patient-based outcomes following radial artery harvesting for coronary artery bypass surgery (CABG). METHODS: A cross-sectional telephone survey of 127 patients who underwent radial artery grafting was undertaken. The parameters assessed included symptoms related to the radial artery harvest site (functional impairment, sensory symptoms, and wound infection) and health related quality of life. RESULTS: A high percentage of patients (67.7%) reported altered sensation, in the hand, in particular around the thenar eminence, in the forearm, or in relation to the incision; this was self-limiting and clinically insignificant in the vast majority of patients. Twelve patients reported residual insignificant symptoms after a median follow-up of 17.5 months. Four patients reported a subjective decrease in grip strength. Patients reported a good quality of life, and there was no association between this and the presence or absence of symptoms related to radial artery harvest. Some patients volunteered a 'preference' for the radial artery harvest site when compared with concomitantly harvested long saphenous vein (LSV), and there was a lower wound infection rate at radial artery harvest sites compared with vein harvest sites (6 vs. 15%). CONCLUSIONS: Sensory symptoms following radial artery procurement occur more frequently than previously reported, but are largely self-limiting and are usually clinically insignificant. Patients appear to have a good quality of life following CABG using the radial artery. Radial artery harvest may be associated with lower wound infection rates and greater patient satisfaction than LSV harvest, however, the presence of residual sensory symptoms may be of relevance when obtaining informed consent.

Coronary Artery Bypass↗

Cold cardioplegic arrest enhances heat shock protein 70 in the heat-shocked rat heart.

BACKGROUND: Myocardial content of the 70-kd heat shock protein has been found to correlate with improved cardiac recovery after ischemia, but the mechanisms and conditions that regulate its level, particularly under clinical conditions, are unclear. The aim of this study was to assess the effect of hypothermic cardioplegic arrest and reperfusion on the expression of 70-kd heat shock protein in a protocol mimicking conditions of preservation for cardiac transplantation. METHODS: Heat-shocked and control hearts were subjected to 4 hours of cardioplegic arrest and global ischemia at 4 degrees C and then to 20 minutes of reperfusion. Hearts were freeze clamped at different time points-after 15 minutes of Langendorff perfusion, at the end of ischemia, and after 20 minutes of reperfusion, and analyzed for heat shock protein 70 content by Western blotting. Another set of hearts was subjected to 10 minutes of normothermic ischemia and 20 minutes of reperfusion followed by freeze clamping and analysis of heat shock protein 70 content as in cardioplegic arrest protocol. Cardiac function was measured by means of a left ventricular balloon at the end of reperfusion. RESULTS: Preischemic concentration of 70-kd heat shock protein was increased in heat-shocked hearts compared with control hearts. The content of 70-kd heat shock protein in heat-shocked hearts was further increased from 5.0 +/- 2.4 ng/microg at the end of ischemia to 11.0 +/- 4.9 ng/microg (n = 8, mean +/- SD; P <.05) at 20 minutes of reperfusion after cold cardioplegic arrest. No further rise in 70-kd heat shock protein of the heat-shocked hearts was observed after normothermic ischemia. Maximal developed pressure was 120.8 +/- 13.4 mm Hg in control hearts compared with 164.7 +/- 22.5 mm Hg in heat-shocked hearts (n = 5, mean +/- SD; P =.037) after cardioplegic arrest. By contrast, after normothermic ischemia, maximum developed pressure was 111.2 +/- 10.9 mm Hg in control hearts compared with 139.2 +/- 11.0 mm Hg in heat-shocked hearts (n = 4, mean +/- SD; P =.031). CONCLUSION: Hypothermic cardioplegic arrest but not short normothermic ischemia triggered a further increase in the level of 70-kd heat shock protein in heat-shocked rat hearts, which may enhance endogenous cardiac protection.

Analysis of Variance↗

Role of endogenous endothelin on coronary reflow after cardioplegic arrest.

OBJECTIVE: Endothelin plays a role in the regulation of basal coronary tone. We hypothesized that low coronary reflow and reduced cardiac function after prolonged ischemia may be due to increased release of endogenous endothelin. METHODS: Using an isolated perfused rat heart, we examined the effect of the addition of various endothelin antagonists during reperfusion after 4 hours of cardioplegic arrest at 4 degrees C. Hearts were freeze-clamped at the end of reperfusion for analysis of high-energy phosphate levels. Results are expressed as the percentages of preischemic values. RESULTS: The addition of bosentan or Ro61-0612 (nonselective endothelin antagonists) resulted in a significant increase in the recovery of coronary flow after 30 minutes of reperfusion (100.9% vs 85.3% [P =.03] and 122.4% vs 83.7% [P <.001], respectively, versus controls). The addition of PD155080 (endothelin A antagonist) had a similar effect (129.5% vs 91.4%, P =.008). BQ788 (endothelin B antagonist) and phosphoramidon (endothelin-converting enzyme inhibitor) had no effect. Myocardial adenosine triphosphate levels were significantly (12.1%) higher after reperfusion with Ro61-0612 (18.1 +/- 0.4 micromol/g vs 16.2 +/- 0.5 micromol/g, P =.01). There was no difference in the recovery of cardiac mechanical function with any of the antagonists studied. CONCLUSION: These results suggest that endogenous endothelin plays a role in low coronary reflow after prolonged cardioplegic arrest but does not impair recovery of myocardial function.

Animals↗

Incremental importance of peak-exercise plasma levels of endothelin-1 and natriuretic peptides in chronic heart failure.

Chronic heart failure (CHF) studies investigating the clinical, hemodynamic, and therapeutic importance of endothelin-1 (ET-1), atrial natriuretic peptide (ANP), and brain natriuretic peptide (BNP) are largely based on resting plasma levels, which may vary with prior exertion and postprandial status. This study investigated the importance of peak-exercise plasma levels of ET-1, ANP, and BNP in the assessment of left ventricular (LV) systolic function. Thirty-six male-patients ages 58 +/- 10 (mean +/- SD ) with NYHA class I-IV CHF due to coronary artery disease or idiopathic dilated cardiomyopathy were enrolled. LV systolic function was assessed by echocardiography and radionuclide ventriculography. Resting and peak cardiopulmonary exercise venous blood sampling and treadmill exercise testing were performed in the fasting state. Resting plasma levels of ET-1, ANP, and BNP were elevated compared with reference laboratory normal values. Exercise induced significant (p < 0.0001) increase in plasma levels of ET-1, ANP, and BNP. On univariate analysis peak-exercise plasma levels of ET-1, ANP, and BNP were more closely related to echocardiographically determined LV end-diastolic diameter and end-systolic diameter than their resting values. Multiple step-wise regression models identified resting and peak-exercise plasma levels of ET-1 and ANP but only the resting BNP as independent predictors of LV dimensions and systolic function. Peak exercise plasma levels of ANP and ET-1 are potentially more reliable and important than their resting levels as markers of LV systolic dysfunction and LV dimensions in patients with heart failure.

Aged↗

Gene therapy for myocardial protection: transfection of donor hearts with heat shock protein 70 gene protects cardiac function against ischemia-reperfusion injury.

BACKGROUND: Heat shock protein 70 (HSP70) gene transfection has been shown to enhance myocardial tolerance after normothermic ischemia-reperfusion. We investigated the effect of HSP70 gene transfection on mechanical and endothelial function in a protocol mimicking clinical heart preservation. METHODS AND RESULTS: Rat hearts were infused ex vivo with Hemagglutinating Virus of Japan-liposome complex containing HSP70 gene (HSP, n=8) or no gene (CON, n=8), and heterotopically transplanted into recipient rats. Four days after surgery, transfected hearts were perfused on a Langendorff apparatus for 45 minutes, arrested with St Thomas' No. 1 cardioplegia for 4 hours at 4 degrees C, and reperfused for 1 hour. Mechanical and endothelial function was studied before and after ischemia. Creatine kinase was measured in reperfusion effluent. Hearts underwent Western blotting and immunohistochemistry to confirm HSP70 overexpression. Postischemic recovery of mechanical function (% preischemic+/-SEM) was greater in HSP versus CON: Left ventricular developed pressure recovery was 76.7+/-3.9% versus 60. 5+/-3.1% (P:<0.05); dP/dtmax recovery was 79.4+/-4.9% versus 56. 2+/-3.2% (P:<0.05); dP/dtmin recovery was 74.8+/-4.6% versus 57. 3+/-3.6% (P:<0.05). Creatine kinase release was attenuated in HSP versus CON: 0.22+/-0.02 versus 0.32+/-0.04 IU/min/g wet wt. (P:<0. 05). Recovery of coronary flow was greater in HSP versus CON: 76. 5+/-3.8% versus 59.2+/-3.2% (P:<0.05). Recovery of coronary response to 5-hydroxytryptamine (5 x 10(-)(5) mol/L) was 55.6+/-4.7% versus 23. 9+/-3.2% (P:<0.05); recovery of coronary response to glyceryltrinitrate (15 mg/L) was not different between HSP and CON: 87.4+/-6.9% versus 84.3+/-5.8% (NS). CONCLUSIONS: In a clinically relevant donor heart preservation protocol, HSP70 gene transfection protects both mechanical and endothelial function.

Animals↗

Randomized controlled study investigating the effect of biatrial pacing in prevention of atrial fibrillation after coronary artery bypass grafting.

BACKGROUND: Atrial fibrillation (AF) is a common problem after CABG. Prevention with prophylactic drug therapy has had limited success, therefore alternative approaches are required. This study investigated the role of biatrial pacing compared with no pacing on AF incidence after isolated first-time CABG. METHODS AND RESULTS: During surgery, temporary pacing leads were placed in the lateral wall of the right atrium and at the roof of the left atrium in Bachmann's bundle to allow bipolar pacing and sensing at each site. After surgery, all patients were connected to an external pacemaker (Chorum ELA) that also acted as a Holter monitor. Patients were consecutively randomized to either 4 days of biatrial pacing at a base rate of 80 bpm or to no pacing (control group, base rate 30 bpm). End points included an episode of AF lasting >1 hour on pacemaker Holter, clinically detected AF, intensive care unit (ICU) and hospital stay, and postoperative complications. One hundred thirty patients were randomized. Biatrial pacing significantly reduced both monitored (13.8% versus 38.5%, P:=0.001) and clinical (10.8% versus 33.8%, P:=0.002) episodes of AF. Median ICU (19 versus 24 hours, P:=NS) and mean hospital stay (7.7+/-6.9 versus 9.7+/-10, P:=NS) did not significantly change. The number of postoperative complications was lower in the biatrial group (13 versus 35, P:=0. 001). CONCLUSIONS: Biatrial pacing after CABG significantly decreases the incidence of AF. This is associated with reduced postoperative complications and a trend toward reduced ICU and hospital stay.

Aged↗

Age dependence of heat stress mediated cardioprotection.

BACKGROUND: To study the influence of age on heat stress cardioprotection, functional recovery, nucleotide concentrations, and heat stress protein 70 (Hsp70) levels were compared in the heat stressed (HS) and control (C) hearts at different ages, in a protocol mimicking donor heart preservation for transplantation. METHODS: Control and heat stressed (24 hours before experiment) rat hearts were divided into three age groups: (I) 1 month, (Y) 4 months, and (M) 16 months (n = 6). Left ventricle balloon catheter was used to determine systolic and end-diastolic pressure/volume relations before and after 4 hours of cardioplegic arrest at 4 degrees C. Another identical set of isolated hearts underwent 5 minutes of normoxic perfusion to obtain preischemic Hsp70 content and metabolite concentrations. RESULTS: The postischemic recovery was highest in group HS-Y as compared to C-Y, HS-I, C-I, HS-M, and C-M. There were no differences in preischemic adenine nucleotides or creatine metabolite concentrations between the three age groups. In contrast, the nicotinamide adenine dinucleotide (oxidized form) (NAD+) and nicotinamide adenine dinucleotide phosphate (oxidized form) (NADP+) concentrations were significantly raised in group HS-Y. Hsp70 content was increased in all HS groups with no difference between the age groups. CONCLUSIONS: Improved postischemic functional recovery after cardioplegic arrest was observed in the young adult HS hearts. This was associated with highest NAD+ and NADP+ concentrations and did not correlate with increased Hsp70 content.

Aging↗

Expression and function of angiotensin converting enzyme, chymase, and angiotensin II in the human radial artery and internal thoracic artery.

BACKGROUND: The potential role of the local renin-angiotensin system to differentially affect radial artery and internal thoracic artery graft performance has not been examined. METHODS: Contractile responses to angiotensin I and II in the radial artery and the internal thoracic artery were examined in vitro. The expression function, and localization of angiotensin receptors, angiotensin converting enzyme, and chymase were studied in radial artery and internal thoracic artery segments. RESULTS: Angiotensin I and II contractions were significantly greater (p < 0.05) in the radial artery compared to the internal thoracic artery. In both arteries, angiotensin II responses were mediated via the AT1 receptor. Messenger RNA transcripts for angiotensin-converting enzyme and chymase were detected in both arteries. Angiotensin-converting enzyme was localized to luminal and vaso vasorum endothelial cells and smooth muscle cells in both vessels, while chymase was colocalized with mast cells in adventitial and medial layers. An angiotensin converting enzyme or a chymase inhibitor singularly had no effect on angiotensin I contractions, however, when combined, a marked inhibition of the angiotensin I response was observed in both vessels. CONCLUSIONS: Our results illustrate the complexities which exist within the local renin angiotensin system and suggest that clinical trials which may modulate the system are warranted.

Aged↗

Interaction between thromboxane A2 and 5-hydroxytryptamine in the radial artery compared to the internal thoracic artery.

The aim of the present study was to investigate if the function of 5-hydroxytryptamine-1B/1D (5-HT1B/1D) receptors in human radial artery (RA) and internal thoracic artery (ITA) can be modified by thromboxane A2 (TXA2) released from the vessel wall in these two arteries that are commonly used in coronary artery bypass grafts. The 5-HT1B/1D agonist sumatriptan contracted the RA with a maximum response of 23.5+/-6.8 mN and a pD2 value of 6.6+/-0.1. The effect of sumatriptan was significantly reduced in the ITA with a maximum of 5.8+/-2.7 mN (P<.05) and a pD2 value of 6.4+/-0.2. The TXA2 receptor antagonist SQ30741 inhibited contractions to sumatriptan in the RA but not in the ITA. It is concluded that the effect mediated by 5-HT1B/1D is augmented by endogenous TXA2 in the RA.

Aged↗

Endothelins and the lung.

Since endothelins were discovered by Yanasigawa in 1988 it has been recognised that they may have an important role in lung pathophysiology. Despite their biological importance as vasoconstrictors the physiological role of endothelin has not yet been defined within the lungs. This review explores their role in acute and chronic disease. During acute inflammation and ischaemia-reperfusion injury cytokines may induce release of endothelin. This is important in the realm of acute lung injury and during surgical procedures such as cardiopulmonary operations including lung resections and transplantation. Complications of surgery including primary organ failure resulting in poor gas exchange as well as increased pulmonary vascular resistance have been linked to the presence of excessive endothelin. Endothelin may have an important role in transplantation biology. The complex process leading to successful lung transplantation includes optimising the donor with brain death, harvesting the lungs, managing acute and chronic rejection, and protecting the vital organs from toxic effects of immunosuppressants. During chronic disease processes, the mitotic action of endothelin may be important in vascular and airway remodelling by means of smooth muscle cell proliferation. We also explore recent advances in drug development, animal models and future directions for research.

Animals↗

[Hydatidosis: apropos of several uncommon locations].

Most hydatid cysts are found in the liver or lungs but occurrence in other locations is possible. The purpose of this report is to describe three cases involving cysts locate in the ovary, joint, and thyroid. Clinical findings associated with these uncommon locations were poorly specific and diagnosis required histological examination after surgical exploration. Imaging and serology were useful to differentiate hydatid cyst from benign or malignant tumor disease but often failed to achieve definitive differential diagnosis. Thorough investigation is necessary to rule out more common locations in the liver or lung. Continued surveillance is needed for early detection of recurrence. Preventive campaigns are necessary in endemic areas, such as Morocco.

Echinococcosis↗