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Biomedical subjects

O Alfieri

Publications and source records attributed to O Alfieri.

At least 91 records · Page 5Linked to original sources
PubMed1994

Left ventricular dysfunction due to stunning and hibernation in patients.

Left ventricular dysfunction is in most cases the consequence of myocardial ischemia. It may occur transiently during an attack of angina and usually it is reversible. It may persist over hours or even days in patients after an episode of ischemia followed by reperfusion, leading to the so-called condition of stunning. In patients with persistent limitation of coronary flow, left ventricular dysfunction may be present over months and years, or indefinitely in subjects with fibrosis, scar formation, and remodeling after myocardial infarction. However, chronic left ventricular dysfunction does not mean permanent or irreversible cell damage. Hypoperfused myocytes can remain viable but akinetic. This type of dysfunction has been called hibernating myocardium. The dysfunction due to hibernation can be partially or completely restored to normal by reperfusion. It is, therefore, important to clinically recognize a hibernating myocardium. In the present article we evaluate stunning and hibernation with respect to clinical decision making and, when possible, we refer to our ongoing clinical experience.

Humans↗
PubMed1994

Coronary artery bypass grafting for left ventricular dysfunction.

In patients with severe coronary disease and poor left ventricular function, coronary artery bypass grafting has a positive impact on long-term survival. In presence of angina or documented ischemia, it is beneficial in protecting functioning muscle against future infarction. In patients with heart failure and no angina, it is a rational option when large areas of akinetic but viable myocardium are identified preoperatively; under these circumstances, recovery of myocardial function is the goal of coronary revascularization. Obviously, reliable methods of assessing myocardial viability and contractile reserve are required for an accurate selection of patients. Advances in perioperative management, including myocardial preservation, have consistently reduced the operative risk in the most recent series, and more appropriate selection criteria have substantially contributed to the improved long-term survival. Variables associated with higher hospital mortality as well as factors influencing long-term outcome have been identified. The beneficial effect of coronary artery bypass grafting on the functional status of patients has been documented in several studies, and the improvement in left ventricular function has been objectively demonstrated. The concepts and the data presented in this review may help to define the present role of coronary artery bypass grafting in the treatment of ischemic cardiomyopathy.

Angina Pectoris↗
PubMed1993

Plasma levels of atrial natriuretic factor (ANF) and urinary excretion of ANF, arginine vasopressin and catecholamines in children with congenital heart disease: effect of cardiac surgery.

We studied the changes in the plasma concentration of atrial natriuretic factor (ANF) and the urinary excretion of ANF, arginine vasopressin (AVP) and catecholamines in 22 children with congenital heart disease, divided into two groups. Group 1 included 11 children with congestive heart failure (CHF), treated with digitalis and diuretics. Group 2 included 11 children without CHF and without medical treatment. Each group was compared with a control group of 15 healthy, age-matched children. The plasma concentration of ANF was raised in both groups, but it was significantly higher in group 1 (235.5 +/- 82.9 pg/ml), compared to group 2 (48.4 +/- 29.4 pg/ml, P < 0.002). Urinary excretion of ANF was measurable in both groups and higher in group 1 (185.9 +/- 116.2 pg/kg per h) than in group 2 (48.5 +/- 30.7 pg/kg per h), but not significantly so. Urinary excretion of AVP and catecholamines was not different in children with congenital heart disease and healthy children. Twenty-four hours after surgery, plasma ANF diminished in group 1 (from 235.5 +/- 82.9 to 93.4 +/- 53.8 pg/ml, P < 0.003), but did not change in group 2. The urinary excretion of ANF was unchanged in both groups. In contrast, urinary excretion of AVP and catecholamines rose significantly in both groups. These data show that plasma ANF is increased in children with congenital heart disease, even in the absence of CHF. The measurement of urinary ANF is less reliable than a plasma assay. The postoperative increases in AVP and catecholamine urinary excretions could be responsible for the vasoconstriction and water retention typical of the postoperative period.

Adolescent↗
PubMed1993

Recovery of myocardial function. The ultimate target of coronary revascularization.

Recovery of myocardial contraction represents an important target of coronary revascularization and the preoperative recognition of viable akinetic (hibernating) myocardium is a crucial point of the preoperative investigation of patients with chronically depressed left ventricular function. In 14 patients dobutamine infusion during echocardiography was utilized to evoke the contractile reserve retained by viable akinetic segments. Redistribution of thallium(TI)-201 after the rest injection was also used to assess the viability of akinetic areas. The wall motion response to dobutamine infusion predicted immediate postoperative improvement in 85 of 93 segments (sensitivity 91.3%) and identified 25 of the 32 segments which did not exhibit early postoperative improvement (specificity 78.1%). Rest redistribution of TI-201 demonstrated high sensitivity (93.0%) but low specificity (43.7%) for predicting the early recovery of regional wall motion. When late recovery was also considered, the specificity of this method increased to 64.0%. Rest distribution of TI-201 identifies viability which is not necessarily associated with the early recovery of function postoperatively. When the echo-dobutamine test is positive, on the other hand, the recovery of function usually occurs immediately after revascularization and the operative risk is expected to be low even in the presence of severely compromised left ventricular function.

Adult↗
PubMed1993

Myocardial damage during ischaemia and reperfusion.

Reperfusion, without doubt, is the most effective way to treat the ischaemic myocardium. Late reperfusion may, however, cause further damage. We attempted to identify the nature and time-course of metabolic changes occurring during ischaemia followed by reperfusion either in isolated and perfused rabbit hearts or in coronary artery disease (CAD) patients undergoing intracoronary thrombolysis or aortocoronary bypass grafting. In isolated hearts, reperfusion after prolonged ischaemia causes exacerbation of cell damage, leading to a breakdown of the permeability barrier of ions as well as of larger molecules, such as creatine phosphokinase. As consequence, reperfusion results in a large increase in intracellular calcium, leading to mitochondrial calcium overload with subsequent damage to the mitochondrial structure and loss of the ability to produce adenosine triphosphate (ATP). The ultimate mediator of the membrane damage is not known. It has been suggested that myocardial production of oxygen free radicals above the neutralizing capacity of the myocytes is an important cause of reperfusion damage. There is evidence that prolonged ischaemia reduces the naturally occurring defence mechanisms of the heart against oxygen free radicals, particularly mitochondrial manganese superoxide dismutase, and the intracellular pool of reduced glutathione. Consequently, reperfusion results in severe oxidative damage, as evidenced by tissue accumulation and release of oxidized glutathione. An oxygen free radical-mediated impairment of mechanical function also occurs during reperfusion of the human heart. During surgical reperfusion of CAD patients, we observed a prolonged and sustained release of oxidized glutathione; the degree of oxidative stress can inversely correlated with recovery of mechanical and haemodynamic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Dynamic cardiomyoplasty as an effective therapy for dilated cardiomyopathy.

Nine male patients with dilated cardiomyopathy unresponsive to maximal medical therapy were submitted to dynamic cardiomyoplasty according to the technique described by Carpentier and Chachques, and preliminary postoperative results are reported. Seven patients were in New York Heart Association (NYHA) Class III and two were in intermittent Class IV. The mean age was 56 years (range 51 to 61 years). Preoperative ejection fraction (EF) by multiple gated acquisition ranged from 14% to 28% (mean 20.7%). No additional surgery was performed. Transesophageal echocardiographic monitoring was used during surgery to guide the wrapping procedure. There was no operative mortality. There was one early death (1 month). One late death (sudden death) occurred 7 months after surgery despite significant clinical improvement. Follow-up ranges from 2 to 16 months. Six patients were submitted to hemodynamic evaluation from 4 to 6 months after surgery by transthoracic and transesophageal echo-Doppler assessment. Effective latissimus dorsi support was clearly documented in all patients by comparing postoperative basal hemodynamic values (Cardiomyostimulator [Medtronic, Inc.] switched off) and data obtained during assisted beats (EF increased from 19.4% +/- 8.6% to 32.6% +/- 13.8%, p = 0.043; and stroke volume increased from 51.6 +/- 20.6 mL to 63.0 +/- 22.0 mL, p = 0.014). All patients who completed the latissimus dorsi training protocol were in NYHA Class I or II. A significant reduction in postoperative medical therapy was achieved in all patients. Our preliminary results confirm that the cardiomyoplasty procedure is to be considered a safe and valuable mean for treating selected patients with dilated cardiomyopathy refractory to maximal pharmacological treatment.

Assisted Circulation↗
PubMed1992

Hibernating myocardium in patients with coronary artery disease: identification and clinical importance.

The term hibernating myocardium describes a particular outcome of myocardial ischemia in which myocytes show a chronically depressed contractile ability but remain viable. Revascularization of hibernating tissue causes a recovery of mechanical function that correlates with long-term survival. Therefore it is important clinically to distinguish hibernating from infarcted myocardium, since asynergies due to hibernation will improve on reperfusion, whilst those due to infarct will not. One suggested technique to identify hibernating myocardium is to stimulate the myocytes acutely, but briefly, by administration of inotropic agents while monitoring contractile function by echocardiography. We report our experience on the use of low dosages of dobutamine. Myocardial viability was validated by measuring the recovery in contraction of the akinetic areas after coronary artery bypass surgery by means of intraoperative epicardial echocardiography. The test has a sensitivity of 93% and a specificity of 78%. It is useful for identification of viable myocardium and also for quantification of intraoperative risk in individual patients. Limitations of this test are related to the presence of downregulation of beta receptors and to the impossibility of differentiating hibernating from stunned myocardium. Another useful technique of identifying hibernating myocardium is the use of radionuclear markers for viability. In our experience the two most important tests are (1) rest-redistribution imaging of thallium 201 (which has a high sensitivity of 93% but a low specificity of 44%) and (2) 99mTc-Sestamibi imaging, which provides information on both perfusion and function with a single injection. This latter technique allows differentiation between stunning and hibernating on the basis of coronary flow which is preserved in stunning and reduced in hibernation.

Cell Survival↗
PubMed1992

[Reconstructive surgery of pure mitral insufficiency. Operative results and follow-up in 128 patients].

Short and long-term results of valve repair for pure mitral insufficiency are reported in 128 consecutive patients with a mean age of 49 years (range 4-75). The etiology of the mitral valve dysfunction was degenerative in 54% of the cases, rheumatic in 30%, ischemic in 9.5%, endocarditic in 6.5%. Preoperatively, 91% of the patients were in NYHA class II or III. The anatomic lesions and the mechanism of mitral regurgitation were identified preoperatively by transthoracic and/or transesophageal echocardiography. Cardiac catheterization was performed only in patients with multiple valvular dysfunction and/or with evidence of concomitant coronary artery disease. Mitral repair was performed according to the techniques proposed by Carpentier. Only one patient died in the hospital (operative mortality: 0.8%). By actuarial methods, 96% of the patients were alive 4 years postoperatively, and 84% were reoperation free. Freedom from reoperation was significantly higher in patients who received a prosthetic ring than in those who had other types of anuloplasty (96% vs 67%; p < 0.05). During the follow-up period no patient had thromboembolic episodes. Ninety-seven per cent of the 112 patients who survived the operation and were not reoperated were in NYHA class I or II. These results confirm the validity of reconstructive surgery in pure mitral insufficiency. The use of a prosthetic ring gives stability to the repair and improves long-term results.

Adolescent↗
PubMed1992

[The short- and long-term results in heart surgery of the elderly].

We have studied retrospectively 106 patients aged 69 years or older (range 69 to 79) who underwent cardiac surgery between November 1986 and December 1989. The majority of patients (61%) were male. Coronary artery bypass surgery was performed in 59 patients, isolated valve replacement in 38 and combined valve replacement with coronary artery bypass surgery in 5. Two patients underwent ascending aorta replacement for aortic dissection and 2 ventricular aneurysmectomy and postinfarction ventricular septal defect repair. The mean postoperative hospital stay was 12 days. Ninety-one percent of patients underwent a primary elective operation and 9% required an emergency operation. Hospital mortality was 5% (n = 6). All hospital survivors were followed up by telephone contact (mean follow-up: 37 months) to determine presence or absence of chest pain, dyspnea, postoperative NYHA class and the overall effect of surgery on quality of life. There were 16 follow-up deaths; 5 were non cardiac. Follow-up study showed significant improvement in symptom status and quality of life (96%). We concluded that cardiac surgery in the elderly, although associated with increased operative risk, gives excellent relief of symptoms and good survival.

Aged↗
PubMed1992

[The accuracy of echocardiography during the infusion of low-dose dobutamine in identifying vital myocardium in patients with obstructive coronary disease and chronic left ventricular dysfunction].

The identification of viable myocardium has important therapeutic implications in patients with coronary artery disease (CAD) and chronic left ventricular dysfunction. To assess the accuracy of transthoracic echocardiography (TTE) during dobutamine infusion for identification of viable myocardium, we have analyzed 14 patients affected by CAD and chronic abnormalities of left ventricular wall motion (RWM), present at rest, referred for coronary artery bypass grafting (CABG): 8 of 14 patients had a history of myocardial infarction with evidence of Q waves at the surface ECG. All patients had a clinical stable CAD. RWM response to dobutamine (5 mcg/kg/min and 10 mcg/kg/min) was evaluated using TTE and compared to RWM changes after CABG analyzed by intraoperative epicardial echocardiography (EE). RWM was analyzed qualitatively by dividing the left ventricle into 16 segments and a score index was assigned to each region (0: normal; 1: hypokinetic; 2: akinetic; 3: dyskinetic). Of 125 akinetic segments present at rest before CABG, 93 showed functional improvement after CABG at intraoperative EE. The RWM response to dobutamine infusion predicted intraoperative improvement after CABG in 85 of 93 segments (sensitivity: 91.3%) and identified 25 of the 32 segments which did not exhibit intraoperative improvement (specificity: 78.1%). The TTE performed 15 days after CABG showed no worsening or further improvement in RWM when compared with intraoperative EE study. Summed segment scores in 14 patients showed significantly improvement from 17.9 +/- 7, medium values at rest, to 5.1 +/- 4 after dobutamine infusion (p less than 0.001) and 5 +/- 7 after CABG (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Oxygen free radicals and myocardial damage: protective role of thiol-containing agents.

It has been suggested that the sudden presence of oxygen during reperfusion after a period of ischemia may be toxic for the myocardial cell. The oxygen molecule is capable of producing reactions in the cell, forming highly reactive free radicals, and inducing lipid peroxidation of membranes, altering their integrity and increasing their fluidity and permeability. The ischemic and reperfused cardiac cell is the prime candidate for this reaction sequence and may explain the molecular mechanism underlying the pathologic events related to membrane dysfunction and calcium homeostasis. However, the myocardium has a series of defense mechanisms including the enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase plus other endogenous antioxidants such as vitamin E, ascorbic acid, and cysteine to protect the cell against the cytotoxic oxygen metabolites. The prerequisite for oxygen free radical involvement in ischemia and reperfusion damage is that ischemia alters the defense mechanisms against oxygen toxicity. It is known that ischemia may impair mitochondrial SOD and, with reperfusion, oxidative stress may occur as shown by tissue accumulation and release of oxidized glutathione. This tripeptide molecule in the cofactor of glutathione peroxidase, the enzyme that removes hydrogen and lipid peroxides. Its formation and subsequent release is a reliable index of oxidative damage. In our study, we investigated the effects of N-acetylcysteine on oxidative damage in the isolated rabbit heart. N-acetylcysteine increases, in a dose-dependent manner (from 10(-7) to 10(-5) M), the myocardial glutathione content and provides an important degree of protection against ischemia and reperfusion. Oxidative stress does not occur, mitochondrial function is maintained, enzyme release is reduced, and contractile recovery is increased. Similarly, we administered N-acetylcysteine in the pulmonary artery of coronary artery disease patients undergoing coronary bypass grafting (150 mg/kg in 1 hour followed by 150 mg/kg in 4 hours). The degree of oxidative stress on reperfusion was reduced and recovery of cardiac function improved. In this article, we review the cardioprotective role of thiol-containing agents.

Animals↗
PubMed1991

Time course of human atrial natriuretic factor release during cardiopulmonary bypass in mitral valve and coronary artery diseased patients.

We determined the time-course of the release of atrial natriuretic factor (ANF) during cardiopulmonary bypass (CPB) in six patients undergoing coronary artery bypass (CAD) and eight patients undergoing valve replacement for mitral stenosis (MS). Before CPB, the arterial ANF was significantly higher in MS patients than in CAD patients (243 +/- 38 and 29 +/- 5.8 pg/ml respectively, P less than 0.01). With the onset of CPB, the acute pressure unloading of the atria induced a significant, rapid decrease of ANF only in MS patients (-64% of pre-CPB value at 5 min) and no major changes in CAD patients. Clamping of the aorta induced a further progressive reduction of ANF release to almost zero in both groups. Readmission of coronary flow to the empty atria with declamping resulted in an increase in the plasma level of ANF in both groups to reach the concentration present in MS patients before CPB. After CPB, the ANF levels decreased in CAD patients while remaining elevated in MS patients. These data suggest that ANF release from human atria depends on atrial filling pressure and other unknown factors.

Adult↗
PubMed1991

Optimal exposure of the mitral valve through an extended vertical transeptal approach.

The mitral valve was approached through a vertical transeptal incision extended into the roof of the left atrium in 111 patients. Good exposure was invariably provided even in unfavorable situations such as a small left atrium combined with right ventricular hypertrophy or a previously implanted aortic prosthesis. The only hospital death in the entire series was not related to this approach to the mitral valve. Due to breakage of the suture in the roof of the left atrium and to incomplete reconstruction of the atrial septum resulting in a large left-to-right shunt, 2 patients required reinstitution of cardiopulmonary bypass. Both had a smooth postoperative course. Other intra- or postoperative complications related to the incision did not occur. Duration of cardiopulmonary bypass and aortic occlusion was not significantly different from that of patients operated upon through the conventional left atrial approach in the year preceding the experience embraced by this study. Only 3 of 52 patients who were preoperatively in sinus rhythm were discharged in atrial fibrillation. Enhanced atrial vulnerability was demonstrated preoperatively in all 3. These data support a wide application of the extended vertical transeptal approach in mitral valve surgery.

Adult↗
PubMed1991

A quality control method in cardiac surgical outcome: experience in 462 patients.

The aim of our study is to verify the reliability, reproductiveness and simplicity of a method to control cardiac surgical results. We divided 462 adult patients, operated on for acquired heart disease from October 1989 to January 1991, into five classes according to an individual score which was predictive for their operative mortality risk. The score resulted from 15 different risk factors tested with univariate and multivariate analysis against one event: operative death. The total number of deaths was 12: 2, 2, 1, 2, 5 for each class respectively. When comparing the predicted versus our observed mortality, we found no statistically significant difference, using the chi-squared test. The method we used is highly predictive for surgical mortality risk: it makes the results objectively comparable among different institutions; it is useful as a self-controlled quality method for cardiac surgical activity in any single institution.

Adolescent↗
PubMed1991

Postinfarction left ventricular free wall rupture: original management and surgical technique.

A case of postinfarction left ventricular free wall rupture is successfully treated. Prompt diagnosis was provided by echocardiography and an emergency operation was carried out. Following sternotomy, hemodynamic stabilization was obtained by gradually evacuating blood from the pericardium, while the femoral vessels were cannulated and the extracorporeal circulation was established. An autologous glutaraldehyde stiffened pericardial patch was sealed over the infarcted area using fibrin glue and fixed with a running suture on the surrounding healthy myocardium.

Echocardiography↗