Biomedical subjects

D Sidi

Publications and source records attributed to D Sidi.

At least 199 records · Page 11Linked to original sources

PubMed1987

Anomalous left coronary artery from the pulmonary artery in infants. Which operation? When?

The surgical management of anomalous left coronary artery from the pulmonary artery in infants and small children remains controversial, because the ideal surgical procedure and the optimal time for operation are yet to be determined. From 1977 to 1985, 22 patients less than 4 years of age (mean age 18.2 months) underwent direct aortic reimplantation of the anomalous left coronary artery. There were five operative deaths (23%, confidence limits 13%-36%). The determinant risk factor of early mortality was the severity of preoperative left ventricular dysfunction (p = 0.05), not age at operation (p = 0.64) or preoperative clinical status (p = 0.36). There were not late deaths (mean follow-up 38 months). All survivors but one were symptom free. The reimplanted anomalous left coronary artery was patent in each reevaluated case (9/17). Left ventricular function improved significantly in all survivors. Moderate to severe preoperative mitral incompetence lessened in all patients but one, without mitral valve repair. When technically feasible, direct aortic reimplantation of the anomalous left coronary artery is an attractive procedure because it offers a high rate of patency and avoids the potential drawbacks of procedures involving autogenous venous or arterial tissue. Optimal intraoperative myocardial preservation and institution of temporary left ventricular assistance at the end of the operation may decrease the operative risk. Left ventricular function nearly always recovers after successful revascularization, and resection of left ventricular myocardium is rarely indicated, if ever. Mitral incompetence almost always lessens, and the mitral valve should not be repaired at initial operation; however, residual mitral incompetence may necessitate reoperation in a few cases. In infants with moderate left ventricular damage (usually asymptomatic with medical therapy), surgical treatment should be delayed until 18 to 24 months of age so that it can be performed with a low operative risk. Infants with severely impaired left ventricular function and persistent congestive heart failure should probably undergo operation as soon as the diagnosis has been made.

Age Factors↗

PubMed1986

[Results of anatomical correction of simple transposition of the great vessels in 46 newborn infants].

Between the 4th April 1984 and 6th December 1984, a strategy of anatomical correction of transposition of the great arteries was undertaken in the newborn if three criteria were respected: parental consent, patient's age of less than 15 days and satisfactory left ventricular geometry. We report our results in 47 consecutive cases operated by the same surgeon at an average age of 8.2 +/- 5.3 days. Atrioseptostomy was performed in all cases before surgery, with a ratio of left to right systolic ventricular pressures greater than 0.66 (m = 0.8) and an infusion of prostaglandin E1 was maintained until surgery in 40 cases. The geometry of the left ventricle assessed by echocardiography was considered to be normal in 23 cases, satisfactory in 22 cases and unfavourable in 2 cases. Except for one case with the great vessels situated in the frontal plane in which an atrial correction was decided upon during surgery, all the patients underwent detransposition under cardiopulmonary bypass without cardiac arrest, irrespective of the coronary anatomy. The pulmonary tract was reconstructed by direct anastomosis with a piece of tanned (first 25 cases) or autologous (following 21 cases) pericardium. There were 18 immediate deaths (17%) but only 4 out of 37 after September 1984 (11%); the causes of failure were: 5 technical errors, 1 irreducible postoperative pulmonary hypertension and 2 probable left ventricular failures. The 38 survivors were followed up for an average of 6.8 +/- 5.4 months (range 1 to 21 months; 28 cases were followed up for over 3 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗

PubMed1986

[Evaluation of the systolic pressure of the right ventricle by echocardiographic study of left ventricular geometry].

Right ventricular systolic pressure is an important parameter in paediatric cardiology. A critical haemodynamic situation is attained if it exceeds the systemic pressure: strain proximal to severe pulmonary stenosis or the result of pulmonary hypertension. In these circumstances, the patient must be closely followed up at the least, and appropriate treatment, often surgical, has to be instituted. Ambulatory methods of assessing this parameter are either unreliable, like the surface electrocardiogram, or relatively complex, like certain ultrasonic methods. We therefore looked for a method relating the systolic pressures of the two ventricles and the end systolic geometry of the left ventricle as assessed simply from a short axis view of the left ventricle at the level of the junction between the chordae and papillary muscles. Two orthogonal diameters are measured and the ratio of the two dimensions calculated: this ratio which we call the "septal curvature" reflects left ventricular compression by the pressure that the right ventricle exerts through the interventricular septum. Seventy-two children aged 6 hours to 18 years (average 5.2 years) hospitalised for pre or post-operative investigation of congenital heart disease were evaluated by this method. The results were compared by statistical analysis with the ratio of ventricular pressures measured directly almost simultaneously during cardiac catheterisation. In general, a linear relation was observed between septal curvature (x) and ratio of pressures (y); y = 0.88, x - 0.63 and R = 0.92.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1985

Developmental changes in myocardial contractile reserve in the lamb.

We have assessed serial changes in myocardial contractility and reserve in the normal lamb over the first month of life using an in vivo adaptation of the endsystolic pressure-volume relationship. Via a left thoracotomy, we insert a catheter tip pressure transducer into the left ventricle, affix an echo transducer onto the left ventricular epicardium, place an electromagnetic flow transducer around the pulmonary artery, and insert catheters for monitoring and infusions. We measure contractility by generating left ventricular wall stress-volume index (the cube of dimension) curves, at the same time increasing afterload by infusing phenylephrine. The slope of the endsystolic wall stress-volume index relationship is our index of contractility. Weekly studies were performed at rest and during isoproterenol infusion in 12 animals, and after propranolol administration in four. The data showed a progressive decrease in resting contractility but no change in maximal contractility during isoproterenol infusion over the 4 wk. Taking each week separately, the average increase in contractility during isoproterenol infusion was small at 1 wk (13%), moderate at 2 and 3 wk (24 and 26%, respectively), and large at 4 wk (79%). beta-Adrenergic blockade with propranolol caused a significant decrease in contractility in three of four animals studied at 1 wk, in only one of four animals at 2 wk, and in none of four animals at 3 or 4 wk. Thus, the newborn lamb shows a limited reserve in contractility that increases progressively with age; the limited reserve appears secondary to a high resting beta-adrenergic state.

Animals↗

PubMed1985

Chronic hypoxemia in the newborn lamb: cardiovascular, hematopoietic, and growth adaptations.

We have created a model of chronic hypoxemia in the newborn lamb by decreasing pulmonary blood flow in the presence of an atrial septal defect. Via a left lateral thoracotomy, we place an inflatable balloon around the pulmonary artery and perform an atrial septostomy under direct vision. We also insert several vascular catheters and place an electromagnetic flow transducer around the ascending aorta. Three days after surgery, we inflated the balloon in 11 lambs such that arterial oxygen saturation decreased to 60 to 75%. Studies were performed on these lambs twice weekly and weekly on 12 normoxemic lambs. Growth decreased sharply (47 +/- 123 versus 221 +/- 82 g/day) at the onset of hypoxemia and remained low, although oxygen consumption followed the normal gradual decline. Heart rate remained elevated throughout the study. Arterial PCO2 levels decreased from 40 +/- 5 to 35 +/- 7 torr and remained low. Systemic blood flow decreased at balloon inflation but quickly returned to normal. Mixed venous saturation was low, but could decrease further with shivering. Systemic oxygen delivery decreased initially but returned to normal as Hb concentration rose (from 9.4 +/- 1.5 to 12.5 +/- 2.2 g/dl). P50 increased normally over the study period. Four of the 11 hypoxemic lambs died during the study. These data show that, in the chronically hypoxemic newborn, systemic oxygen delivery is maintained primarily by a rising Hb. Total body oxygen consumption is maintained at rest but is redistributed away from anabolic requirements and toward cardiorespiratory work. This signal to decrease growth occurs despite less than maximal oxygen extraction at rest.

Animals↗

PubMed1985

[Medical treatment and long-term development of permanent reciprocal tachycardia in children. Apropos of 10 cases followed for 11 years].

Incessant reciprocating tachycardia (IRT) was diagnosed in 10 children aged 0-11 years (mean 2.5 years), followed-up for an average of 11 years (range 4-22 years). 8 children were treated for an average period of 2.8 years (range 0.5-6 years) with the association of amiodarone and digitoxine. All children were treated initially or secondarily with verapamil and/or betablockers with digitoxine for an average of 4.6 years (range 1-9 years). The true frequency of IRT, its tolerance and the age at diagnosis did not indicate the probable required length of treatment with amiodarone, but only the initial response to this drug. Finally, 5 patients were cured and in sinus rhythm, and the other 5 were well controlled, having only occasional bursts of tachycardia. When we compared one group of 5 cases with clinical signs of cardiac failure and radiological cardiomegaly (CTR greater than 0.60) with a second group of 5 cases in which the arrhythmia was better tolerated, surprisingly, the frequency of intreated IRT was not t he factor which influenced its tolerance (198/min vs 194/min). On the other hand, the following differences were observed between the two groups: a younger age at diagnosis in the first group (5 months vs 4.6 years) responsible for the longer follow-up period (14.5 vs 7 years), earlier treatment period with amiodarone (3.6 years compared to 5.5 years) and a longer treatment period with this drug (3.5 vs 2 years). It was only at about the age of 7 that this treatment could be withdrawn or changed with half the children completely cured, and the other half only controlled.(ABSTRACT TRUNCATED AT 250 WORDS)

Amiodarone↗

PubMed1985

[Antenatal cardiac surgery. Creation of an experimental model of pulmonary stenosis in the fetus and repair in utero].

An experimental model of pulmonary stenosis was created in ewes, fetus and repaired before birth by making use of the materno-foetal circulation. Eighteen ewes fetus underwent pulmonary artery banding at an average of 87 +/- 8 days' gestation (normal 135-145 days). All were reoperated before term at 132 +/- 6 days' gestation. They were divided into two groups : group I (7 fetus) was used to evaluate the experimental model of pulmonary stenosis by measuring right ventricular pressures (80 +/- 16 mmHg compared to 58 +/- 10 mmHg in control models), and the increase in right ventricular mass (2.8 +/- 0.5 X 10(-3) g vs 1.9 +/- 0.2 X 10(-3) g), left ventricular mass (2.2 +/- 0.3 X 10(-3) g vs 1.8 +/- 0.4 X 10(-3) g) and septal mass (1.8 +/- 0.3 X 10(-3) g vs 1.3 +/- 0.2 X 10(-3) g). In group II (11 fetus) the pulmonary stenosis was repaired by total clamping and patch repair. After repair and during the days just before birth, the ventricular masses decreased (RV = 2 +/- 0.3 X 10(-3) g; LV = 1.8 +/- 0.4 X 10(-3) g; septum = 1.8 +/- 0.3 X 10(-3) g) approaching values of normal control fetus. This experimental model shows that it is possible to correct cardiac lesions in utero by making use of the materno-fetal circulation and that antenatal repair of an arterial obstruction can rapidly reverse the reactional ventricular hypertrophy.

Animals↗

PubMed1984

Anatomic correction of transposition of the great arteries associated with ventricular septal defect: midterm results in 50 patients.

From May 1977 to August 1982 50 patients who were 1.5 to 44 months old underwent anatomic correction of transposition of the great arteries (TGA) and closure of ventricular septal defect (VSD) at our institution. Thirty-nine patients underwent preliminary pulmonary arterial banding. Hospital mortality was 32%: four patients died as a result of technical problems, seven as a result of associated lesions, three of pulmonary hypertension, and two of left ventricular failure. Three other patients died after the first postoperative month (one of mediastinitis, one at reoperation for a residual VSD, and one of pulmonary hypertension). All 31 survivors are in excellent clinical condition and are in sinus rhythm after a mean follow-up period of 31 +/- 14 months. Twenty-five patients were reinvestigated by echocardiography (M mode and two-dimensional) and/or catheterization. Parameters of left ventricular contractility were within normal limits, but systolic aortic diameter was larger than normal (p less than .01). Seven patients had stenosis of the right ventricular outflow tract and five of these required reoperation. The two persistent problems with the anatomic correction of TGA associated with VSD are a relatively high operative mortality and secondary right outflow tract stenosis. However, use of this procedure results in better left ventricular function and fewer arrhythmias than does use of atrial repair techniques and also results in the use of the anatomically left ventricle as the systemic ventricle.

Cineangiography↗

PubMed1984

Effects of nitroprusside on cardiac function, blood flow distribution, and oxygen consumption in the conscious young lamb.

Resting cardiac output is high relative to body weight during the neonatal period and there is a limited reserve for further increasing cardiac output. We assessed the effect on the circulation of reducing peripheral vascular resistance by infusing high doses of sodium nitroprusside in 1- and 3-week-old lambs. In a dose of 5 micrograms X kg-1 X min-1 over 1 h, nitroprusside caused a decrease in aortic and left atrial pressure, an increase in heart rate, and no significant changes in cardiac output or oxygen consumption. Infusing 10 micrograms X kg-1 X min-1 for 2 h resulted in an initial marked decrease in aortic pressure, cardiac output, and also heart rate. Within 50 min aortic pressure gradually increased, but was still well below control levels, while cardiac output returned to control level and heart rate slowly increased. Distribution of cardiac output and organ blood flows was measured by the radionuclide microsphere method. Blood flows to the kidneys and to the skin fell markedly, but flows to other organs did not change significantly.

Aging↗

PubMed1984

[Surgical treatment of complete atrioventricular canal in early infancy].

Ninety children with complete atrioventricular canal without any significant associated abnormality underwent surgery between 1973 and 1982. The first group of 26 infants, including 7 with trisomy 21 (average age 5.3 +/- 3.8 months) had severe pulmonary hypertension and underwent pulmonary artery banding: 10 died in the immediate or early postoperative period (38 p. 100). The mortality was 50 p. 100 in children under 6 months of age. In two cases, the banding was a failure because it was ineffective or "vicious" and both patients had to undergo reoperation 2 to 6 months later for total correction which resulted in 1 death and 1 poor result; the surviving 14 patients were improved: 3 are waiting for total correction under good conditions and 11 underwent open heart surgery 36 +/- 16 months after banding with 7 good results and 4 average results because of residual significant mitral regurgitation associated in one case with atrioventricular block requiring pacing. The overall results of this group were 42 p. 100 mortality, 19 p. 100 average results and 27 p. 100 good results; 12 p. 100 are waiting for surgery. The second group included 64 children, with 34 with trisomy 21 (average age 17.4 +/- 16.7 months) who underwent complete correction straight away (before 2 years in 50 cases, before 1 year in 30 cases). The operative mortality was 28 p. 100, but only 7 p. 100 in the 15 cases in which pulmonary atrial pressure did not exceed 2/3 of the systemic pressure and 35 p. 100 in the other 49 cases with severe pulmonary hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1984

[Severe tracheo-bronchial compression caused by a circumflex aorta. Apropos of 3 cases treated by aortic uncrossing].

The cases of three children with an encircling right aortic arch and left sided descending aorta illustrate the fact that this rare abnormality may cause severe compression of the tracheo-bronchial axis. A ventricular septal defect was associated to the abnormal vascular arch in all three cases. The compressive structure was the aorta and these children could only be extubated after surgical uncrossing . Before diagnosing tracheomalacia in a child operated for an abnormal vascular arch, residual compression must be excluded by tracheo-bronchial fibroscopy.

Aorta, Thoracic↗

PubMed1984