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Biomedical subjects

G Ducharme

Publications and source records attributed to G Ducharme.

28 records · Page 2Linked to original sources
PubMed1982

Hang-out time of pulmonary valve in d-transposition of great arteries.

Recently it has been shown that in patients with transposition of the great arteries the isometric relaxation time of the left ventricle could be negative in the presence of normal pulmonary artery pressure. In order to find an explanation for this apparently paradoxical situation, it was decided to evaluate the importance of the delay of closure of the pulmonary valve in 15 patients with transposition of the great arteries. This delay is called the hang-out time. The hang-out time was found to correlate inversely with the isometric relaxation time as well as with the pulmonary artery systolic (r = -0 . 70) and mean pressures. A weaker correlation was found between the isometric relaxation time and the time of mitral valve opening. These results show that in transposition of the great arteries with normal pulmonary artery pressure, the pulmonary valve has a prolonged hang-out time, to the extent that it frequently closes after the opening of the mitral valve, explaining the negative isometric relaxation time found in these cases. This finding may help in the non-invasive assessment of the pulmonary vascular resistance of patients with transposition of the great arteries.

Child, Preschool↗
PubMed1982

Cardiac dimensions and myocardial function of infants with congenital hypothyroidism. An echocardiographic study.

This study was undertaken to evaluate the cardiac dimensions and various indices of myocardial function, determined by echocardiography, in a group of 12 infants with congenital hypothyroidism. Left ventricular systolic and diastolic dimensions, posterior wall thickness, enddiastolic and systolic volumes were all significantly lower in the hypothyroid infants compared with 25 normal infants of the same age. No pericardial effusion was found. Hypothyroid infant had a lower heart rate with a reduced cardiac output. The mean velocity of circumferential fibre shortening and the shortening fraction of the left ventricle were normal. The pre-ejection period of the left ventricle (PEP), however, was abnormally prolonged as well as the ratio PEP over left ventricular ejection time (PEP/ET). This ratio correlated inversely with the end-diastolic volume, suggesting that the increased PEP/ET could be partly the result of decreased preload.

Cardiac Volume↗
PubMed1982

Variations of cardiac rate and hemodynamic criteria of rejection.

Since heart rate influences the values of many hemodynamic parameters, the authors have examined the effect of heart rate variations noted after cardiac transplantation on the hemodynamic criteria of rejection. They have undertaken serial studies at intrinsic rate and at a paced atrial rate of 150 beats/min in 11 resting homotransplanted dogs. The authors analysed cardiac index, stroke volume, peak velocity, acceleration, stroke power and stroke work. Results at intrinsic and paced atrial rates were compared during each of three phases of postoperative evolution: phase II (2 to 3 days after transplantation), phase III (4 to 5 days) and phase IV (6 to 7 days postoperatively). Phase II, being the period of maximum recovery, served as a baseline for comparing the cardiac parameters in phases III (the initial phase of rejection) and phase IV (24 hours before death). The authors found that the patterns of change were similar at intrinsic and paced atrial rates and concluded that heart rate variation does not significantly influence the hemodynamic criteria of rejection.

Animals↗
PubMed1982

[Neonatal electrocardiographic manifestations of congenital hypothyroidism. Correlation with echocardiographic data].

Twelve infants, average age 5, 4 weeks (range 3 to 8 weeks) with congenital hypothyroidism were studied. In addition to routine evaluation including plasma T3, T4 and TSH estimation and the establishment of a clinical index of hypothyroidism on electrocardiogram and an echocardiogram were performed. The following variables were analysed: heart rate, QRS axis in the frontal plane, PR interval in Lead II, corrected QT interval in V5, amplitude of the P waves in Lead II, R waves in V3R, V1, V5 and V6; S waves in V1, V2 and V4 and T wave in V6. The ventricular activation time in V5 and QRS duration in V3R, V1 and V6 were also measured. The presence of pericardial effusion, left ventricular posterior wall and septal thickness, and left ventricular internal diastolic and systolic dimensions were determined by echocardiography. The following conclusions were drawn: 1. The ECG of hypothyroidism in the neonatal period is characterised by the low amplitude of the left ventricular potentials while increased conduction times were much less evident; 2. Only the sum of R + S in V2, the amplitude of the T wave in V6 and increase in QRS duration in V3R were influenced by severity of hypothyroidism; 3. Left ventricular microvoltage is not due to pericardial effusion which was absent in all our cases.

Congenital Hypothyroidism↗
PubMed1982

Renal transplantation and cardiac function in pediatric patients.

Nine pediatric patients underwent echocardiographic evaluation prior to and after renal transplantation. Prior to transplantation parameters of cardiac contractility such as mean velocity of circumferential fiber shortening, ejection time, ejection fraction and shortening fraction were within the normal ranges for the age group. Post transplantation there was a significant decrease in heart rate and cardiac index. In addition a dramatic increase in hemoglobin levels was observed. The improvement in circulating hemoglobin levels rather than the removal of uremia appears to be the dominant beneficial result in improving cardiovasuclar hemodynamics.

Adolescent↗
PubMed1980

Relation between isovolumic relaxation period of left ventricle and pulmonary artery pressure in d-transposition of the great arteries.

The study aimed to identify the best echocardiographic time interval (systolic or diastolic) for assessing pulmonary artery pressure in children with d-transposition of the great arteries. Echocardiograms were performed in 21 children with d-transposition of the great arteries within 48 hours of cardiac catheterisation. None of the children had had a Mustard procedure. Twenty-four recordings were obtained, three patients having been catheterised twice. Highest correlations were found for the ratio of the isovolumic relaxation time over the ejection time of the left ventricle (IRT/LVET) to the systolic pressure in the pulmonary artery and also between IRT/LVET and the difference between mean pulmonary artery pressure and mean left atrial pressure. All patients with a negative IRT/LVET ratio had a pulmonary systolic pressure lower than 35 mmHg and a mean pulmonary pressure lower than 25 mmHg. In patients with d-transposition, a negative IRT/LVET ratio appears to be a reliable indication of normal pressure in the pulmonary circulation. Serial echocardiographic studies for the follow-up of patients with d-transposition should include measurement of the time of relaxation of the left ventricle.

Blood Pressure↗
PubMed1980

Isovolumic contraction time of right ventricle in d-transposition of great arteries.

The pre-ejection period of the right ventricle in d-transposition of the great arteries is known to be prolonged, compared with the same interval of the left ventricle of normal subjects. In the present study, the echocardiographic measurement of the components of the pre-ejection period of the right ventricle of 14 patients with d-transposition of the great arteries shows that the isometric contraction time of the right ventricle in d-transposition of the great arteries is similar to the same interval calculated on the left ventricle of 76 normal children of comparable age. On the other hand, the electromechanical delay was significantly greater for the right ventricle of d-transposition of the great arteries than for the left ventricle of the normal subjects. It is concluded that the prolonged pre-ejection period of the right ventricle in d-transposition of the great arteries is not the result of right ventricular dysfunction but solely of a longer electromechanical delay.

Adolescent↗
PubMed1980

Effects of hemodialysis on myocardial function in pediatric patients.

The effect of hemodialysis on myocardial function in 10 pediatric chronic hemodialysis patients was assessed utilizing echocardiography. Parameters of cardiac function were measured prior to and immediately after dialysis. A significant decrease in cardiac output was observed post-dialysis. Unlike that observed in adult patients a real improvement in myocardial function as indicated by an increase in the mean velocity of circumferential fibre shortening was evident post-dialysis.

Acetates↗
PubMed1979

The effects of Brescia-Cimino fistulas and cardiac function in transplanted pediatric patients.

The cardiac hemodynamic effects of patent Brescia Cimino fistulas were assessed using non-invasive techniques in 10 pediatric patients who had undergone successful renal cadaveric transplantation. All had hemoglobin levels above 11 g/dl and had serum creatinine values of less than 1.5 mg/dl. Studies were done prior to and after temporary fistula occlusion to assess the effect of fistula patency on parameters of cardiac function. Values obtained prior to fistula occlusion were compared to those obtained in a normal control population. It was noted that though fistula patency did significantly alter cardiac function, changes were such that fistula patency could be safely maintained. It was also noted that the difference in cardiac index prior to and after occlusion provided a good assessment of fistula flow.

Adolescent↗