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Biomedical subjects

C Chartrand

Publications and source records attributed to C Chartrand.

117 records · Page 7Linked to original sources
PubMedDate not supplied

Effects of PGE1 in experimental vasoconstrictive pulmonary hypertension.

The pulmonary vascular and systemic effects of PGE1 were studied in a canine model of pulmonary hypertension. Systemic arterial, central venous and pulmonary arterial pressures were monitored and an electromagnetic flow probe was placed around the ascending aorta for continuous cardiac index (CI) measurements. Through a laparotomy, an arteriovenous fistula was created between the abdominal aorta and inferior vena cava. Gradual opening of this fistula significantly affected CI and these values were used to generate pressure-flow curves (pulmonary arterial pressure (PAP)/CI). Following PGF2 alpha infusion (5-10 micrograms/kg/min) significant pulmonary hypertension was observed (2- to 3-fold increase in PAP). PGF2 alpha infusion also resulted in a significant rise in heart rate and systemic vascular resistance (SVR) while CI was reduced. PGF2 alpha significantly increased both the line slope (vascular resistance) and intercept (outflow pressure) of the pressure-flow curves. Intravenous PGE1 infusion in doses ranging from 40 to 320 ng/ml/min elicited a dose-dependent reduction of both pulmonary and systemic vascular resistances, the former being slightly more affected. With PGE1 infusions only the intercept of the pressure-flow curve was affected suggesting that specific components of the pulmonary vascular bed modulating the outflow pressure were involved. High doses of PGE1 significantly decreased arterial PO2, indicating that this prostaglandin derivative deteriorates pulmonary gas exchanges.

Alprostadil↗
PubMedDate not supplied

Efficacy of dobutamine in the failing transplanted heart.

Acute rejection often leads to severe myocardial failure and death. Surprisingly, no systematic study on the efficacy of beta-adrenergic pharmacologic agents have been reported to the present. Because of all the pathophysiologic alterations documented during rejection, we expected an inappropriate response to inotropic drugs, so we have questioned the value of dobutamine during those circumstances. Twelve dogs underwent orthotopic transplantation and were prepared with implantable devices for serial hemodynamic studies to be performed on the resting unanesthetized subject. Of this number, six dogs were studied while they were in immediate postoperative heart failure (3 hours after operation), and the same study was performed when myocardial failure secondary to rejection occurred (5 to 7 days). After basal state measurement, 5 and 10 micrograms.kg-1.min-1 of dobutamine were infused continuously, and the hemodynamic response during the two phases was compared. The baseline cardiac index in the immediate postoperative period was 1.4 +/- 0.4 L.min-1.m2 and 1.8 +/- 1.0 L.min-1.m2 during rejection, showing a similar degree of heart failure. Dobutamine (5 micrograms.kg-1.min-1) increased cardiac index by 97% 3 hours after transplantation and by 35% during rejection (p < 0.05). With 10 micrograms.kg-1.min-1 of dobutamine, the difference between increments was not significant (99% versus 79%). Raising the infusion rate of the drug to 15 and 20 micrograms.kg-1.min-1 during rejection increased cardiac index by 97% and 118%, respectively. Interestingly, no detrimental tachycardia occurred with this increased dosage. Heart failure secondary to acute rejection can therefore be improved by dobutamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

Long-term assessment of renal function under cyclosporine in pediatric heart transplant recipients.

Renal function was monitored in eight children who were long-term survivors of heart transplantation and who were treated with cyclosporine. Both creatinine clearance and true glomerular filtration rate remained normal 17 to 69 months after transplantation. The survival rate was 80% at 6, 12, and 24 months, and the rejection rate in survivors was only 0.37. Thus adequacy of renal function can be preserved, without jeopardizing overall transplant results, by using small doses of cyclosporine.

Azathioprine↗
PubMedDate not supplied

Coronary vascular reactivity after heart transplantation in dogs: nitroglycerin-induced response.

Coronary reactivity during rejection still remains an unresolved question. Evidence of residual coronary dilator reserve would lend support to the therapeutic approach of increasing myocardial blood flow during episodes of acute rejection. This hypothesis was tested in canine heart transplants. Fourteen orthotopic heart transplantations were performed and electronic implants were positioned for long-term hemodynamic studies. Of the 14 study dogs, nine were nonimmunosuppressed; five dogs with transplants received standard triple therapy (cyclosporine, azathioprine, and prednisone). Nitroglycerin challenge consisted of an intravenous bolus administration at a dose of 4 to 5 micrograms/kg. This pharmacologic challenge was performed 3 hours after surgery, 2 to 3 days after transplantation, and 24 hours or less before death for the nonimmunosuppressed group. Nitroglycerin always exerted its peripheral vasodilator effect: arterial pressure decreased by 20% and total peripheral resistance by 25% to 35%, which favors the observed increment in cardiac index. There were, however, significant differences in the cardiac effect of nitroglycerin: during acute rejection this effect was severely blunted (less than 10%). On the contrary, coronary blood flow always increased after nitroglycerin administration (40% in the postoperative period, 42% in immunosuppressed dogs, and 33% during acute rejection). These results indicate that nitroglycerin elicits its coronary vasodilator effect despite acute rejection episodes. The concept of a functional reversible vasoconstrictor component present during acute rejection gains support from this study and brings a challenging new avenue for therapeutic approaches.

Animals↗
PubMedDate not supplied

Pediatric heart transplantation: surgical considerations for congenital heart diseases.

Congenital anomalies of the atrium, of the pulmonary and systemic venous return, and of the great vessels are sometimes regarded as contraindications to heart transplantation. Among 10 children who underwent heart transplantation in our institution, five, aged 4 to 15 years and weighting 9 to 32 kg, previously operated on, had congenital anomalies. These lesions, encountered singly or in association, were single atrium (2), previous Mustard operation (1), hypoplastic left atrium (1), anomalous systemic venous return (3), anomalous pulmonary venous return (2), transposition or malposition of the great vessels (5), pulmonary artery hypoplasia (1). To enable correction of these lesions and to perform heart transplantation, the donor heart preparation was modified in four ways. The surgical techniques used for correcting these anomalies in this group were atrial septation, atrial enlargement, superior and inferior reroofing, double venous rerouting, septal realignment, full-length mobilization of the great vessels, and pulmonary artery reconstruction. All children survived operation and left the hospital in excellent condition. Follow-up ranged from 6 months to 3 years. All children are totally asymptomatic. As demonstrated by echocardiography, heart catheterization, and angiography, there are no stenoses, no shunts, and there is good atrial size and good orientation of the great vessels. On the basis of our experience, we conclude that with appropriate surgical techniques, most atrial, venous return, and intrapericardial great vessel anomalies are correctable at the time of orthotopic transplantation and that these techniques allow for a successful outcome in children.

Anastomosis, Surgical↗
PubMedDate not supplied

Intravenous infusion of phentolamine: effects on cardiovascular dynamics and regional blood flow distribution in conscious dogs.

We have studied hemodynamic changes induced by infusion of phentolamine (100 micrograms/kg/min) over 15 min in conscious dogs in order to clarify its mechanism of action. Dogs were prepared with an electromagnetic flow probe, and microspheres (9 microns) were used to measure regional blood flow distribution before and after 15 min of infusion of phentolamine. Controlled hypotension (15-20%) was maintained throughout the infusion, and this hypotensive state was associated with the following significant changes: heart rate increased by 50-70%, stroke volume decreased by 35-42%, left ventricular power and work fell by 15-19% and by 49-56%, respectively, maximum acceleration increased by 26-34%, and total peripheral resistance decreased by 20% while cardiac index was unaffected. Regional blood flow studies showed that phentolamine at the 15th min of infusion induced a significant increase in blood perfusion to all components of the myocardium (range 30-51%) while their vascular resistances showed a significant decrease (35-41%). Blood flow to liver (hepatic artery), spleen, and intestine was also modified (-14, -14, and -15%, p less than 0.05) while their vascular resistances were only slightly decreased. At the time measurements were made, blood flow to cerebral and renal tissues was not affected while their local vascular resistances decreased significantly (15-20%). For each organ studied blood perfusion was uniform. These results indicate that phentolamine elicits both central and peripheral hemodynamic changes and that in most vascular beds studied the vasodilator effect of phentolamine can still be observed at the 15th minute of infusion.

Animals↗
PubMedDate not supplied

[Myocardial protection of the homograft. III - Evaluation of ventricular fibrillations with hypothermic coronary perfusion (author's transl)].

The homotransplanted heart is in severe failure in the immediate post-operative period, secondary to ischemia inherent to the technic of orthotopic transplantation. The present work was carried out to investigate if ventricular fibrillation followed by cold coronary perfusion could protect the homograft during implantation by evaluating the post-operative cardiac performance. In the control group, 7 hearts were excised, immediately immersed in physiological saline at 5 degrees C, and homotransplanted. In a second group of 4 grafts, ventricular fibrillation was induced and the coronary bed was perfused immediately with cold (5 degrees C) extracellular solution for a period of 10 minutes before orthotopic implantation. All animals were prepared at the end of surgery for hemodynamic studies to be carried out 3, 24 and 48 hours post-operatively in the resting state. In group I, the myocardial temperature dropped to 13.5 degrees C in 14.5 minutes. In group II, the hypothermia by perfusion was more rapid and deeper (11 degrees C within 10 minutes). Three hours post-operatively, cardiac function of group II was superior to that of group I as demonstrated by the increase of cardiac index (39%), stroke volume index (41%) mean systolic ejection rate index (44%), maximum systolic flow index (58%), maximum acceleration index (36%), stroke power index (88%), stroke work index (67%). Twenty-four and forty-eight hours post-operatively the cardio-vascular function improved in both groups but remained superior in group II. These results demonstrate that ventricular fibrillation followed by cold coronary perfusion increases protection of the homograft during the initial period of implantation.

Animals↗
PubMedDate not supplied

Impact of research on pediatric pain assessment and outcomes.

PURPOSE: Pediatric nurses from varied practice and educational backgrounds learned about research by doing a ward-based study. The aim of the study was to determine if regular assessment of children's pain would improve their pain management and postoperative progress. METHOD: Children, ages 5 to 17 years (n = 36), measured their pain every 4 hours postoperatively using the Wong-Baker Faces Pain Rating Scale. Outcomes regarding amount of analgesic given, subjective pain reports, time and progress of ambulation, and length of hospital stay were compared with data from a retrospective chart-review of a control group (n = 50). FINDINGS: No statistically significant differences in these variables were found. An important clinical finding was that despite all children having prescribed PRN analgesic orders, one quarter of the children received no pain relief intervention. Also, one quarter of the children stated that their pain control was only partially effective. CONCLUSIONS: Study results reinforce findings reported in the literature regarding ineffective pain management in children, and highlight a need for improved nursing practice. Clinical significance was achieved in terms of staff learning of the research process, increased awareness of pediatric pain management practices, improved ward morale, and inter-agency sharing of resources.

Adolescent↗