Search PubMed⌕ Search

Biomedical subjects

A Corno

Publications and source records attributed to A Corno.

At least 19 recordsLinked to original sources
PubMed1995

Myocardial metabolism and function in acutely ischemic and hypoxemic isolated rat hearts.

We tested the hypothesis that residual oxygen supply during acute low-flow ischaemia or hypoxemia is a major regulator of myocardial performance, metabolism and recovery. Rat hearts were exposed for 20 min to either ischemia (coronary flow reduced to 10% of baseline), hypoxemia (oxygen content reduced to 10% baseline) or a "mixed" condition (combined ischaemia and hypoxemia). The oxygen supply (coronary flow x oxygen content) was matched in all groups (n = 16 per group). Hypoxemic hearts had the highest performance (systolic and developed pressures, +/- dP/dtmax and oxygen uptake) and content of IMP and AMP. Ischaemic hearts had the highest content of ATP, phosphocreatine, adenine nucleotides and purines. As flow and/or oxygenation were restored, post-ischemic hearts showed better functional and metabolic recovery than post-hypoxemic ones. "Mixed" hearts were more similar to hypoxemic ones during oxygen shortage but to ischemic ones during recovery. We conclude that as oxygenation is critically limiting, coronary flow is relatively more important than oxygen supply in determining myocardial function, metabolism and recovery, most likely secondary to changes in the metabolism of diffusible substances.

Adenine Nucleotides↗
PubMed1994

Effects of energy demand in ischemic and in hypoxemic isolated rat hearts.

Aim of this study was to assess the role of O2, lactate and energy demand in the regulation of myocardial work during severe dysoxia. For this purpose, we measured function and metabolism in isolated Langendorff-perfused rat hearts exposed to either ischemia or hypoxemia (matched for the O2 supply, 10% of baseline) with/out electrical stimulation. When hearts could adjust their HR, hypoxemia demanded more energy than ischemia (p < 0.05) despite same O2 supply. Venous PO2 was 12 +/- 2 or 139 +/- 20 mmHg (p < 0.0001), respectively, but VO2 was the same. After 10 min at HR = 300 min-1, myocardial performance increased in ischemic but not in hypoxemic hearts. PvO2 and VO2 were not affected by pacing. In contrast, both venous [lactate] and lactate production rate increased, but in ischemic hearts only. We conclude that ischemic hearts were downregulated while hypoxemic hearts were not. Likely, depressed washout of lactate during ischemia could offset the effects of O2 in severely dysoxic hearts. Anaerobic glycolysis provided the energy necessary to meet increased energy demand in ischemic hearts, but could not exploit this action in hypoxemic hearts probably because in these hearts it was already working near maximum.

Anaerobiosis↗
PubMed1994

Oxidative injury in reoxygenated and reperfused hearts.

In this study, we separated the effects of low oxygen supply and low coronary flow in isolated perfused rat hearts to focus on the genesis of free radicals-induced reperfusion injury. Hearts were exposed to either hypoxemia/reoxygenation or ischemia/reperfusion in various sequences, with hypoxemia and ischemia matched for duration (20 min), temperature (37 degrees C), and oxygen supply (10% of baseline). Hypoxemia/reoxygenation (n = 7) resulted in lower (developed pressure) x (heart rate) (p < 0.001) and higher end-diastolic pressure (p < 0.001) than ischemia/reperfusion (n = 9). The presence of 40 IU/ml superoxide dismutase and 104 IU/ml catalase nearly blunted the rise of the end-diastolic pressure (p = 0.02 vs. baseline), but could only partially prevent the depression of myocardial contractility (p < 0.001 vs. baseline, n = 7). Similar patterns were observed when hearts were made ischemic after hypoxemia, eliminating the intermediate reoxygenation step. We conclude that the major determinant of the reperfusion injury is associated with low oxygen supply rather than low coronary flow. Part of the injury is mediated by oxygen-derived free radicals, but a substantial portion of it is associated with energetic processes.

Analysis of Variance↗
PubMed1994

Regulation of bioenergetics in O2-limited isolated rat hearts.

Assessing the role of O2 supply in the regulation of cardiac function in O2-limited hearts is crucial to understanding myocardial ischemic preconditioning and adaptation to hypoxia. We exposed isolated Langendorff-perfused rat hearts to either ischemia (low coronary flow) or hypoxemia (low PO2 in the perfusing medium) with matched O2 supply (10% of baseline). Myocardial contractile work and ATP turnover were greater in hypoxemic than in ischemic hearts (P < 0.05; n = 12). Thus, the energy demand was higher during hypoxemia than during ischemia, suggesting that ischemic hearts are more downregulated than hypoxemic hearts. Venous PO2 was 12 +/- 2 and 120 +/- 15 Torr (P < 0.0001) for ischemic and hypoxemic hearts, respectively, but O2 uptake was the same. Lactate release was higher during hypoxemia than during ischemia (9.7 +/- 0.9 vs. 1.4 +/- 0.2 mumol/min, respectively; P < 0.0001). Electrical stimulation (300 min-1; to increase energy demand) increased performance in ischemic (P < 0.005) but not in hypoxemic hearts without changes in venous PO2 or O2 uptake. However, venous lactate concentration and lactate release increased in ischemic (P < 0.002) but not in hypoxemic hearts, suggesting that anaerobic glycolysis provides the energy necessary to meet the increased energy demand in ischemic hearts only. We conclude that high intracellular lactate or H+ concentration during ischemia plays a major role as a downregulating factor. Downregulation disappears in hypoxemic hearts secondary to enhanced washout of lactate or H+.

Animals↗
PubMed1992

Epicardial damage induced by topical cooling during paediatric cardiac surgery.

OBJECTIVE: To study electrocardiographic changes in infants and children in whom topical cooling was used during surgical repair of congenital heart defects. DESIGN: A retrospective study of all patients who had surgical repair of congenital heart disease during cold blood cardioplegia and topical cooling from January to August 1990. Eleven patients (group 1) had topical cooling with ice and 15 (group 2) with cold saline. PATIENTS: All 36 paediatric patients operated on during this period. All the available electrocardiographic records were analysed. Ten patients in whom reliable records were not available were excluded. Twenty six patients entered in this retrospective study. INTERVENTIONS: Topical cooling with ice or with a slush of cold saline. MAIN OUTCOME MEASURE: Recordings from all the precordial leads were examined and scored as the sum of the maximum ST elevation (mV) in each precordial lead. The score obtained for each electrocardiogram was recorded together with the timing of the electrocardiogram (preoperative, arrival in intensive care unit immediately after surgery, postoperatively in the intensive care unit, and at discharge). RESULTS: There were no differences between the two groups in terms of demographic data, diagnosis, duration of ischaemia, and postoperative myocardial performance. There was temporary ST elevation during the first 48 postoperative hours in all the children in group 1 but in only seven of the 15 children in group 2 (Fisher's test, p less than 0.005). The mean (SD) score for maximum ST elevation was 1.34 (0.83) mV in group 1 and 0.52 (0.64) mV in group 2 (Student's t test, p less than 0.01). CONCLUSIONS: These temporary electrocardiographic changes in the presence of adequate myocardial performance were attributed to epicardial damage induced by hypothermicosmotic injury. The use of ice for topical cooling may damage the epicardium in children.

Adolescent↗
PubMed1992

"Acquired" subvalvular aortic stenosis after repair of a ventricular septal defect.

Of 353 children who underwent surgical repair of a congenital heart defect, including closure of a ventricular septal defect (VSD), 12 patients (four with tetralogy of Fallot, five with a VSD, and three with a double-outlet right ventricle) developed subaortic stenosis, which was diagnosed one to six years after the surgical procedure. Five patients required surgical treatment of the subaortic stenosis, and one required percutaneous balloon angioplasty. Postsurgical subaortic stenosis appears to be an uncommon progressive acquired disease.

Aortic Stenosis, Subvalvular↗
PubMed1992

Total extracardiac right heart bypass.

BACKGROUND: Total cavopulmonary connection has been proposed as a rational alternative to atriopulmonary connection for complex Fontan operations. In addition to fluid dynamic advantages proposed by de Leval, total right heart bypass may address an emerging important issue after repair of single ventricle: late atrial arrhythmias. The purpose of this study is to document the postoperative hemodynamic findings in 22 consecutive patients who received a total extracardiac right heart bypass with an inferior vena cava-to-pulmonary artery extracardiac Dacron conduit with a modified Glenn anastomosis (superior vena cava-to-pulmonary artery anastomosis). METHODS AND RESULTS: Twenty-eight patients with complex congenital heart disease underwent this surgical procedure. One patient died (early mortality, 3.5%). Mean follow-up was 13.9 months. Postoperative cardiac catheterization and echo Doppler studies were performed in 22 of the 27 survivors. In 18 of 22 patients, hemodynamic data were satisfactory; a preferential direction of caval flows to both lungs was observed. Echo Doppler assessments show that forward cavopulmonary flow appears as a predominant early diastolic event, in contrast to what occurs in atriopulmonary connections. This hemodynamic model emphasizes the possible role of the diastolic ventricular performance (as a "suction pump") in Fontan circulation. Early postoperative atrial arrhythmias were observed in two of the survivors. CONCLUSIONS: The technical advantages and the hemodynamic benefits of this form of right heart bypass are encouraging. Although the use of artificial material in this procedure is extensive, none of the survivors showed thromboembolic complications or peel formations with narrowing and/or obstruction. Further investigations during a longer follow-up are needed to confirm the early and intermediate results, especially the reduction of late atrial arrhythmias.

Anastomosis, Surgical↗
PubMed1990

Ventricular septal defect in Down syndrome. Anatomic types and associated malformations.

Ventricular septal defect is a common cardiac anomaly in Down syndrome. To detect the prevalence of anatomic types and associated cardiac malformations we analyzed the echocardiographic and angiocardiographic findings of 73 children with ventricular septal defect and Down syndrome. We compared these results with those obtained in 303 patients with ventricular septal defect without Down syndrome. The prevalence of inlet ventricular septal defect was significantly higher in patients with Down syndrome, while muscular and subpulmonary ventricular septal defects were present only in patients without Down syndrome. The incidence of a cleft of the mitral valve was significantly higher in Down syndrome, while left-ventricular inflow and outflow obstructions were present only in patients without Down syndrome. Different patterns of ventricular septal defect and associated anomalies exist in patients with and without Down syndrome.

Abnormalities, Multiple↗
PubMed1990

Atrioventricular canal in Down syndrome. Prevalence of associated cardiac malformations compared with patients without Down syndrome.

The atrioventricular canal is the "classic" congenital heart anomaly in Down syndrome. We may learn more of the nature of this disorder by careful study of the anatomic characteristics of the cardiac lesions and by comparing these lesions in patients with and patients without Down syndrome. We reviewed the clinical characteristics (echocardiographic and angiocardiographic) of 220 patients with atrioventricular canal and compared the prevalence of anatomic types and associated cardiac malformations in children with (105) and without (115) Down syndrome. In patients with Down syndrome, the complete form of atrioventricular canal was prevalent, with a high frequency of associated Fallot's tetralogy. Partial atrioventricular canal and left-sided anomalies were more common in patients without Down syndrome. Down syndrome is associated with a simpler type of atrioventricular canal when compared with patients with a normal chromosome configuration.

Coronary Circulation↗
PubMed1990

Total anomalous pulmonary venous connection: surgical repair with a double-patch technique.

A double-patch technique has been used to repair total anomalous pulmonary venous connection in 35 patients (mean age, 4.9 months; mean weight, 4.2 kg). In all patients with supracardiac or subdiaphragmatic type of total anomalous pulmonary venous connection, repair has been accomplished by enlarging the "new" left atrium. There were three early deaths (3 of 35 = 8.6%) and no late deaths in a mean follow-up of 30 months (3 to 71 months). We propose this double-patch technique as an alternative surgical option for total anomalous pulmonary venous connection.

Anastomosis, Surgical↗
PubMed1990

Systemic atrioventricular conduit for extracardiac bypass of hypoplastic systemic atrioventricular valve.

The management of severe congenital mitral stenosis in infants and children is still controversial. We describe our experience with the use of a systemic atrioventricular (SAV) extracardiac conduit to bypass a hypoplastic systemic atrioventricular valve. An SAV extracardiac conduit has been used in six patients (left atrium--left ventricle in five, right atrium--right ventricle in one). One hospital death occurred due to mediastinitis and there were two late deaths, one due to progressive subaortic stenosis and one sudden, possibly due to arrhythmia. Postoperative cardiac catheterization performed in five patients showed reduction of the transmitral gradient from a mean of 16 mmHg to a mean of 5 mmHg. Calcification of the bioprosthetic valve occurred in two patients 3 1/2 years and 2 years respectively after the operation; one died from concomitant subaortic stenosis and one underwent conduit replacement. Although its long-term efficacy is limited, the SAV conduit seems the most reliable surgical option for infants and children with hypoplastic systemic atrioventricular valves unsuited to conventional surgery.

Aortic Coarctation↗
PubMed1990

Pediatric cardiac surgery guided by echocardiography. Established indications and new trends.

Cardiac surgery in 602 children was not preceded by cardiac catheterization, the diagnosis being based on clinical findings and two-dimensional and Doppler echocardiography. In the 355 operations without cardiopulmonary bypass there were nine major and seven minor diagnostic errors (2.5% and 2%). Among the 247 cases with open-heart surgery there were no major and eight (3.2%) minor errors. The malformations most suitable for nonbypass surgery without catheterization seem to be those with reduced pulmonary blood flow requiring systemic-pulmonary artery shunt, aortic coarctation and patent ductus arteriosus. For open-heart surgery without invasive investigation, atrial septal defect, partial atrioventricular canal, aortic and pulmonary stenosis, cardiac tumor and isolated valve disorder are 'classic' candidates. Recent experience indicated that selected cases of complete atrioventricular canal, tetralogy of Fallot, truncus arteriosus, total anomalous pulmonary venous connection and transposition of the great arteries may safely undergo primary repair without cardiac catheterization. Because of its diagnostic potentialities, pediatric cardiac surgeons must become familiar with echocardiography.

Cardiac Catheterization↗
PubMed1990

Inferior vena cava-pulmonary artery extracardiac conduit. A new form of right heart bypass.

From November 1988 to May 1989, four patients underwent total right heart bypass by means of bidirectional cavopulmonary anastomosis and interposition of an extracardiac conduit from the inferior vena cava to the pulmonary artery. All of them had an uneventful postoperative course, and there have been no early or late deaths. We propose this technique as an alternative surgical option in candidates for a Fontan procedure with (1) hypoplasia or atresia of the left atrioventricular valve, (2) common atrioventricular valve, (3) anomalies of systemic and pulmonary venous return, or (4) auricular juxtaposition.

Arteriovenous Shunt, Surgical↗