Biomedical subjects

M H Leblanc

Publications and source records attributed to M H Leblanc.

7 recordsLinked to original sources

PubMed1999

Changes in left ventricular mass and function after aortic valve replacement: a comparison between stentless and stented bioprosthetic valves.

The objective of this study was to compare stentless bioprostheses with stented bioprostheses with regard to the postoperative changes in left ventricular (LV) mass and function. Forty patients with aortic stenosis undergoing valve replacement with a stentless (20 patients) or a stented (20 patients) bioprosthesis were evaluated early (baseline), 1 year, and 2 years after operation. Left ventricular mass index was calculated with the corrected American Society of Echocardiography formula. The relative changes between end-diastole and end-systole in LV mid-wall radius, length, and volume (ejection fraction) were determined with a previously validated model for dynamic geometry of the left ventricle. Overall, a significant decrease was found in LV mass index (from 155 +/- 30 to 112 +/- 23 g/m(2); P <.001) and a significant increase in longitudinal shortening (from 0.12 +/- 0.11 to 0.22 +/- 0.08; P <. 001), and ejection fractions (from 0.67 +/- 0.11 to 0.71 +/- 0.10; P =.017). No significant change was found in the mid-wall radius shortening fraction. Two years after surgery, the extent of LV mass regression was greater in stentless bioprostheses (-51 +/- 18 vs -35 +/- 17 g/m(2); P =.01), though the average mass index was similar in both groups (114 +/- 26 vs 110 +/- 20 g/m(2)). Also at 2 years, the longitudinal shortening fraction was greater in patients with a stentless bioprosthesis (0.25 +/- 0.07 vs 0.18 +/- 0.08; P =.03). In conclusion, this study suggests that the superior hemodynamic performance of stentless bioprostheses may have some benefits with regard to LV mass regression and function after aortic valve replacement. The significance of these benefits in terms of prognosis remains to be determined.

Aged↗

PubMed1994

Postnatal penicillin prophylaxis and the incidence of group B streptococcal sepsis in neonates.

We conducted a retrospective chart review of infants, born over a 3-year period, who had positive urine latex agglutination and/or positive blood culture for group B streptococci (GBS). Infants routinely received intramuscular aqueous penicillin for the first half of the study period, and no penicillin was given for the subsequent 18 months. Overall, infants who received penicillin prophylaxis had a decreased incidence of clinical sepsis and positive blood culture for GBS (4.8/1,000 versus 8/1,000 and 1.3/1,000 versus 5.4/1,000, respectively). The incidence of GBS sepsis during the time of penicillin prophylaxis was not different from that in previously reported studies. When analyzed by weight groups, no difference in clinical sepsis or positive blood cultures for GBS was seen in the subset of infants weighing < or = 2,500 g at birth. There were fewer positive blood cultures in the infants who received penicillin and met the criteria for clinical sepsis. Mortality from GBS sepsis was unchanged during these two study periods in all weight groups.

Female↗

PubMed1992

[Measurement of cardiac output by Doppler echocardiography at the 4 cardiac valves].

Many observers remain sceptical with regards to the utilization of Doppler-echocardiographic measurements of intracardiac outputs for the quantification of shunts and regurgitations. In this context, we evaluated the feasibility and validity of measuring output at the level of the four cardiac valves in a population of 35 normal subjects (24 M, 12 F) aged from 23 to 37 years (mean +/- SD = 28 +/- 4). Measurement of stroke volume and output using predetermined criteria was possible in the aortic position in 35 (100%) subjects, in the mitral position in 34 (97%), in the pulmonary position in 20 (57%) and in the tricuspid position in 10 (29%). In 14 subjects (40%), measurement was possible at 2 sites, in 14 (40%) at 3 sites and in 7 (20%) at 4 sites. Inability to measure output was most often due to poor visualization of valvular annulus. There are excellent correlations between aortic stroke volume on the one hand and the mitral (r = 0.97, SEE = 3.41 cc), pulmonary (r = 0.97, SEE = 3.69 cc) and tricuspid (r = 0.96, SEE = 2.77 cc) stroke volumes respectively on the other. These results suggest that reliable measurements of output are feasible in a majority of cases in the aortic and mitral positions but to a much more limited extent in the pulmonary and tricuspid positions; given the small SEE's, they should be useful to quantitate shunts and regurgitations, when feasible.

Adult↗

PubMed1985

[Rehabilitation after aorto-coronary bypass and return to work].

In Quebec, deceptively few patients who have successfully undergone coronary artery bypass have been returning to work. Those aged 55 to 64 years, blue collar workers or those who were off work for 13 weeks or more were likely not to return to work after surgery. From Jan. 1, 1983, all patients aged 64 years and younger, who successfully underwent coronary artery bypass grafting were invited to attend a 6-week rehabilitation program, starting 6 weeks after operation. The aim of the program was to improve the rate of return to work through a low-intensity physical activity course (60% to 70% maximal working capacity and calisthenics ). Up to Mar. 31, 1984, 68 patients had participated in the program. The proportion of patients returning to work was significantly (p less than 0.01) improved and the trend was observed in all age groups, and for all types of employment and length of time off work before operation.

Adult↗

PubMed1984

Effect of polycythemia on vascular volume in the newborn dog.

The effect of polycythemia [hematocrit (Hct) 64-80] on blood volume (BV) was studied in 27 unanesthetized, splenectomized newborn dogs (age 6-14 days, postsplenectomy 5-13 days). Normovolemic polycythemia (N) was induced in nine pups by exchange transfusion with 75 ml/kg of adult, packed (to Hct 95) red blood cells (RBC). Hypervolemic polycythemia (H) was induced in 11 pups by transfusion of RBC (50 ml/kg). Seven pups received exchange transfusion with 75 ml/kg of whole blood and served as controls (C). Red cell volume (RCV, 51CrRBC) and plasma volume (PV, 125I-fibrinogen and Evans blue) were measured prior to and at 1, 2, and 4 h after transfusion, before the pups received fluid orally. The pups were fed 8 ml X kg-1 X h-1 after 4 h, and measurements were repeated at 8 and 24 h. BV fell in C prior to 4 h by 10 +/- 4% (SD) (P less than 0.01) and then rose to initial levels. BV rose in the N pups by 17 +/- 9 (P less than 0.01), 14 +/- 5 (P less than 0.01), 9 +/- 10 (P less than 0.1), 17 +/- 9 (P less than 0.01), and 31 +/- 17% (P less than 0.01) at 1, 2, 4, 8, and 24 h post transfusion. BV rose in the H pups by 41 +/- 8, 35 +/- 10, 23 +/- 11, 27 +/- 6, and 43 +/- 9% (all P less than 0.01). Thus newborn dogs with induced N or H equilibrate rapidly to a BV significantly higher than C levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1984

Relative efficacy of radiant and convective heat in incubators in producing thermoneutrality for the premature.

To determine which warming system more closely approximates a neutral thermal environment, the oxygen consumptions of 16 premature babies less than 1500 g were measured in a convectively heated incubator and a radiantly heated incubator. Both systems were controlled to maintain a skin temperature of 36 degrees C. The oxygen consumptions of the infants were not significantly different in the two incubators; thus, there was no detectable advantage to the use of convective or radiant energy in approximating a neutral thermal environment in an incubator for the small premature infant. That proportion of total heat loss from the babies due to radiant losses in the convective incubator was directly calculated from incubator temperature using equations described in the paper, and found to be 68 +/- 3% SE.

Birth Weight↗

PubMed1981

Echocardiographic assessment of valvular pulmonary stenosis in children.

It has been suggested that the maximal amplitude of the pulmonary valve motion following atrial contraction (Amax) may be useful in the clinical evaluation of patients with valvular pulmonary stenosis. To evaluate the specificity and sensitivity of this measurement in children, we reviewed the echocardiograms of the pulmonary valve of 120 subjects: 57 normal individuals, 25 patients with secundum atrial septal defect and without pulmonary hypertension, and 32 patients with pulmonary stenosis proven at catheterisation (mild in 16 patients, moderate in nine, and severe in seven). Amax ranged from 0 to 12 mm in the normal subjects, and from 2 to 16 mm in those with atrial septal defect. In mild pulmonary stenosis, Amax ranged from 2 to 12 mm, in moderate pulmonary stenosis from 2 to 14 mm, and in severe pulmonary stenosis, from 3 to 12 mm. Though mean Amax was significantly larger in patients with moderate and severe pulmonary stenosis compared with normal subjects, there was much overlap between the two groups so that individual cases could not be identified correctly from this measurement. No significant difference was observed when comparing Amax values of patients with atrial septal defect and those of patients with pulmonary stenosis of various severity, nor were any observed between the pulmonary stenosis groups. These findings indicate that Amax is neither specific nor sensitive for the presence or severity of valvular pulmonary stenosis in children, and that it cannot be used to evaluate non-invasively the results of pulmonary valvotomy.

Adolescent↗