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Biomedical subjects

C Chartrand

Publications and source records attributed to C Chartrand.

At least 73 records · Page 4Linked to original sources
PubMed1985

Use of the internal mammary artery for preservation of circulation to the left arm after subclavian flap aortoplasty in correction of coarctation in children.

In 14 children aged 4 to 12 years in whom the anatomy of the coarctation did not allow for an end-to-end anastomosis, we have performed a subclavian flap angioplasty. To correct the inconvenience of ligating the subclavian artery and to avoid the use of synthetic material, we used the internal mammary artery to reestablish circulation from the aorta to the subclavian artery. All patients are well. At postoperative catheterization (18 to 42 months, average 24) in the first eight, the mammary artery was patent and the flow to the subclavian was good.

Aortic Coarctation↗
PubMed1984

Effects of propranolol and exercise on cardiac dynamics and organ blood flow distribution in dogs.

The additive effects of propranolol and exercise on peripheral blood flow distribution were studied in conscious dogs. During treadmill exercise (8-10 km/h and 0% grade for 15 min.) cardiac performance increased significantly in parallel with myocardial and muscular blood flow (greater than 100%). Blood perfusion to liver and spleen decreased significantly (30% and 34%) while blood flow to other organs was unaltered. Under resting conditions propranolol only modified blood flow to liver and spleen (-50% and -38%). During exercise after propranolol a limited augmentation in cardiac performance and in myocardial and muscular blood flow was observed; splanchnic blood flow which was most affected by propranolol at rest did not further decrease during exercise after propranolol. The present observations demonstrate that propranolol, despite minor haemodynamic modifications, induces significant alterations in blood flow to splanchnic organs. The influence of beta-adrenoreceptor blockade was even more evident under conditions of augmented sympathetic activity as reflected by a significant limitation of increase in cardiac performance, myocardial and muscular blood flow and by a sustained redistribution of splanchnic blood flow during exercise after propranolol.

Animals↗
PubMed1984

The cardiovascular effects of hypertonic sodium bicarbonate in conscious dogs: underlying mechanisms of action.

Mechanisms underlying the transient hypotensive effect (central or peripheral) of rapid bolus administration of hypertonic sodium bicarbonate (NaHCO3) were studied in conscious dogs. Thirteen animals equipped with an electromagnetic flow probe positioned around the ascending aorta were utilized. NaHCO3 (18.5 mequiv. of 1786 mosmol/L), hypertonic saline solution having the same sodium concentration as NaHCO3, and mannitol solution with the same osmolarity as NaHCO3, were injected in the right and in the left atrium. Intra-arterial NaHCO3 was tested to assess its direct peripheral vascular effects. Blood ionic as well as acid-base modifications following NaHCO3 were also studied. Our results indicate that right atrial injection of NaHCO3 elicited transient hypotension (-10 to -15 mmHg (1 mmHg = 133.322 Pa)) and myocardial depression as revealed by a significant decrease of stroke volume (-8%), stroke power (-18%), stroke work (-12%), maximum systolic flow (-13%), peak velocity (-13%), and maximum acceleration (-24%). When the solution is injected in the left atrium, myocardial depression is more pronounced suggesting that the coronary bed is the site of action. Hypertonic saline injections indicate that the sodium load plays a role in this decrement of myocardial function while hyperosmolarity per se, as exemplified with mannitol injections, elicits no negative effect. Transient ionic as well as acid-base disturbances are other mechanisms that have to be considered along with coronary vasoconstriction. Decrement in peripheral resistance appears only with right intra-atrial NaHCO3 suggesting that the pulmonary vascular bed is the origin of this reflex.

Acid-Base Equilibrium↗
PubMed1984

Hypotension and arteriovenous shunting: effects of intravenous infusion of nitroprusside, nitroglycerin and phentolamine.

The effects of nitroprusside, nitroglycerin and phentolamine on cardiac dynamics and on the fraction of cardiac output shunted through systemic arteriovenous communications, which may explain disparate responses elicited by these systemic vasodilators upon venous return, have been studied in 15 nonanesthetized dogs. Cardiac dynamic parameters were measured by electromagnetic flow probe placed at the root of the aorta. Quantitative measurements of total systemic arteriovenous shunting were determined from the fraction of 9 mu radioactively labeled microspheres, injected into the left atrium, recovered in the pulmonary artery. To provide a common basis for comparison, the mean arterial pressure was lowered by 15-20% either with an intravenous infusion of nitroprusside, nitroglycerin or phentolamine. At the fifteenth minute of infusion, nitroprusside produced significant decrease in stroke volume index (23%) and left ventricular power and work (28% and 40%). Nitroglycerin decreased significantly stroke volume index (12%), cardiac index (9%) and left ventricular work (22%). Phentolamine significantly increased heart rate (72%) and left ventricular maximum acceleration (30%) while it decreased stroke volume index (41%), left ventricular power and work (19% and 55%). Total peripheral resistance was significantly affected only by infusion of phentolamine (-18%). Left ventricular maximum velocity, mean systolic ejection rate and maximum systolic flow did not change significantly under infusion of these systemic vasodilators. Under control conditions, total systemic shunting of cardiac output averaged 8.9-10% and was not modified by any of the vasodilators used. Arteriovenous O2 difference and oxygen consumption, corroborated these findings since they remained within normal limits before and after infusion of nitroprusside, nitroglycerin or phentolamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Effect of nitroglycerin on regional myocardial blood flow following an experimental coronary spasm.

This study was designed to evaluate the effect of nitroglycerin (30 micrograms given as an i.v. bolus) on regional distribution of myocardial blood flow in conscious dogs, following an acute coronary occlusion similar to a coronary spasm. The left anterior descending (LAD) coronary artery was acutely occluded with a balloon cuff occluder. The distribution of blood flow between the endocardium and the epicardium of both the normal and ischemic area of the left ventricle was determined by means of the radioactive microsphere technique. Acute occlusion of the left anterior descending coronary artery produced a significant decrease of blood flow reaching the area irrigated by this artery; this decrease was of a lesser magnitude after administration of nitroglycerin. In addition, ischemia produced a disproportionate decrease in endocardial blood flow. This decrement was also of a lesser magnitude following administration of nitroglycerin. Blood perfusion to the non-ischemic myocardium was not altered. These results indicate that an intravenous bolus of nitroglycerin, given after a brief coronary occlusion simulating a coronary spasm, increases blood flow to the ischemic myocardium, induces a favorable redistribution of blood flow toward the ischemic endocardium and does not produce any decrement of blood perfusion to the non-ischemic myocardium.

Animals↗
PubMed1984

Effects of peroperative myocardial ischemia on early and late hemodynamic response to hypertonic sodium bicarbonate in dogs.

Because hypotension induced by the administration of hypertonic sodium bicarbonate is more severe when cardiac performance is impaired, the authors evaluated the hemodynamic consequences of peroperative myocardial ischemia upon the response of conscious dogs to an intravenous bolus of sodium bicarbonate. Twenty-two control dogs (group 1) were equipped with an electromagnetic flow probe positioned around the ascending aorta. Seventeen dogs (group 2), equipped in the same manner, were subjected to 1 hour of myocardial ischemia combined with topical cardiac hypothermia. Hemodynamic studies were performed daily for 1 month before and during the administration of sodium bicarbonate. Baseline hemodynamic values in group 1 were always within normal limits. In group 2, cardiac failure was evident in the immediate postoperative period but hemodynamic values reached normal limits 24 hours postoperatively. For both groups, the peak hypotensive response to sodium bicarbonate was combined with a substantial reduction in all hemodynamic values reflecting the left ventricular performance. However, this response is significantly (p less than 0.01) more pronounced in group 2 during the first 4 postoperative days, being maximal 3 and 24 hours after operation. Afterwards, the hemodynamic response to sodium bicarbonate was similar in both groups. These results indicated that an intravenous bolus of sodium bicarbonate decreases left ventricular performance and that this decrement is greater when cardiac performance is impaired following peroperative myocardial ischemia. Long-term hemodynamic studies show that this temporary myocardial ischemia is not deleterious to cardiovascular adaptability to hypertonic sodium bicarbonate administration.

Animals↗
PubMed1984

[Rupture of a congenital aneurysm of the sinus of Valsalva].

The ruptured aneurysm of the sinus of Valsalva is a rare congenital anomaly which we encountered in less then 1% of our surgical patients. We recently operated on a young girl suffering from this congenital malformation consisting of a 15 mm long fistula arising from the right coronary sinus and giving rise to a 6 cm aneurysm which dissected the interatrial septum as well as the posterolateral wall of the right atrium before rupturing into this cavity. Because of the unusual presentation of this malformation, which has never been described previously, we though worthwhile reporting this case in details. We also summarized the embryological, anatomopathological, clinical and surgical aspects discussed in the literature.

Aorta↗
PubMed1983

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

Intravenous infusion of nitroprusside (5 micrograms/kg/min) was carried out in conscious dogs over a 15-min period in order to describe changes in both central and peripheral vascular areas. Dogs were prepared with an electromagnetic flow probe positioned at the root of the aorta, and microspheres (9 microns) were used to measure regional blood flow distribution before and after 15 min of infusion. Controlled hypotension (-15 to -20 mmHg) was maintained throughout the infusion period and this hypotensive state was associated with a significant decrease in stroke volume (-16%), left ventricular power (-25%) and work (-40%) while cardiac index was not significantly affected. Those values were almost back to control levels 5 min following the end of infusion. Regional blood flow studies showed that at the fifteenth min of infusion, nitroprusside induced a significant decrease in blood perfusion to all areas of the myocardium (range -10% to -25%) while their local vascular resistances were not affected significantly. Blood perfusion to liver (hepatic artery), spleen and intestine was also modified significantly (-17%, -12% and -16%, respectively) while their vascular resistances remained close to control values. By the time measurements were made, blood flow to cerebral and renal tissues remained normal while their vascular resistances fell significantly (15% for brain and 20% for kidneys). For each organ studies, blood perfusion was uniform. These results indicate that nitroprusside elicits both central and peripheral hemodynamic changes and that reflex adjustments modify the vasodilator effect of the drug in most vascular beds that we have studied.

Animals↗
PubMed1982

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

We have studied both central and peripheral hemodynamic changes induced by infusion of nitroglycerin (55 micrograms/kg per minute) over a 15-min period in conscious dogs to clarify its mechanism of action. Dogs were prepared with an electromagnetic flow probe positioned at the root of the aorta, and microspheres (9 microns) were used to measure regional blood flow distribution before and after 15 min of infusion. Controlled hypotension (-15 to -20 mmHg (1 mmHg = 133.322 Pa)) was maintained throughout the infusion period and this hypotensive state was associated with a significant decrease in stroke volume (-30%), cardiac index (-20%), and left ventricular work (-43%). Regional blood flow studies showed that at the 15th min of infusion, nitroglycerin induced significant decrease in blood flow to all components of the myocardium (range -12 to -20%) while their vascular resistances were not affected significantly. Blood perfusion to liver (hepatic artery), spleen, and intestine was also modified significantly (-22, -18, and -16%, respectively) while their vascular resistances remained close to control values. By the time measurements were made, blood flow and vascular resistance of cerebral and renal tissues remained normal. For each organ studied, blood perfusion was uniform. These results indicate that nitroglycerin elicits both central and peripheral hemodynamic changes and that local reflex adjustments modify the vasodilator effect of the drug in most vascular beds that we have studied.

Animals↗
PubMed1982

Plasma catecholamines, heart rate, and cardiac sympathetic activity in exercising dogs.

Plasma catecholamines, heart rate, and cardiac sympathetic activity in exercising dogs. Med. Sci. Sports Exercise, Vol. 14, No. 4, pp. 291-285, 1982. The purposes of the study were, 1) to assess the respective roles of locally released norepinephrine in the sinus node and of plasma catecholamines in the control of heart rate during exercise and 2) to verify whether the heart is a source of plasma catecholamines during exercise. Plasma catecholamines (radioenzymatic assay) and heart rate were measured in the last minute of a 5-min exercise period (3.2 km . h-1, 39% slope) in six normal dogs, in six dogs treated with 5 mg . kg-1 sotalol, and in six dogs sympathectomized with 50 mg . kg-1 6-hydroxydopamine. Compared to the exercise heart rate values of the normal dogs (228 +/- 8 beats . min-1) and the sympathectomized dogs (226 +/- 9 beats . min-1), the sotalol-treated dogs had significantly lower rates (148 +/- 6 beats . min-1). However, plasma catecholamine response was higher in the sotalol-treated dogs (7380 +/- 1350 pg . ml-1) and in the sympathectomized dogs (4280 +/- 680 pg . ml-1) than in the normal dogs (1890 +/- 360 pg . ml-1). Since the action of plasma catecholamines on the sinus node is potentiated by denervation hypersensitivity, it is suggested that in exercising normal dogs, heart rate control could be ensured by locally released norepinephrine rather than by plasma catecholamines. Plasma catecholamines were assessed in six normal dogs at rest and at various exercise levels (HR = 90-200 beats . min-1) and in blood sampled simultaneously in the aorta and the coronary sinus. Plasma catecholamines in the coronary sinus and aorta were similar at rest (490 +/- 90 vs 580 +/- 80 pg . ml-1, respectively) and at the low-intensity exercise (710 +/- 140 vs 880 +/- 120 pg . ml-1, respectively). For moderate and severe work loads, plasma catecholamine concentrations in the coronary sinus (960 +/- 160 and 1570 +/- 340 pg . ml-1, respectively) were lower than in the aorta (1380 +/- 260 and 2950 +/- 100 pg . ml-1, respectively). These results suggest that in exercising dogs the heart is not a source of plasma catecholamines.

Animals↗
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↗
PubMed1981

Effects of cardiopulmonary bypass on the dynamics and coronary circulation of the normal heart.

This study observed the consequences of total normothermic cardiopulmonary bypass (CPB) on cardiac function, myocardial blood flow, and its regional distribution. To determine the potential effects of CPB per se on hemodynamic performance of the heart from the concomitant interfering influences of anesthesia, surgical procedure, and preexisting disease, myocardial function and blood flow were investigated in two groups of normal animals submitted to identical experimental conditions, except for two hours of total CPB, which was performed in only one group. Myocardial blood flow distribution was studied immediately before and after CPB, and the hemodynamic studies were performed 3, 24, and 48 hours postoperatively in the awake resting animal. Coronary blood flow and its distribution were similar before and after CPB. Three hours postoperatively, the hemodynamic status of the perfused dogs seemed to be slightly inferior compared with control subjects; however, there was no statistically significant difference between the two groups. Twenty-four and 48 hours after surgery, the cardiovascular dynamics were similar in both groups. These results demonstrate that two hours of total normothermic cardiopulmonary bypass have no significant deleterious effect on the performance, coronary perfusion, and its regional distribution, of the normal beating empty heart.

Animals↗
PubMed1981

Palliative surgery in tetralogy of Fallot.

Because much controversy surrounds the palliative surgical treatment of young children with tetralogy of Fallot the authors review their experience over 13 years with two procedures--the Blalock-Taussig operation and the Waterston shunt. Blalock shunts were performed 195 times in 172 patients; 147 had a single Blalock anastomosis which carried them through the critical period and allowed for later correction of the tetralogy. Thrombosis of the Blalock anastomosis occurred in two patients in the early postoperative period. In 23 patients a second shunt was necessary after the first Blalock shunt became inadequate in spite of being patent. The age of the children ranged from 2 weeks to 9 years, 74% being operated upon under the age of 2 years. There were four early deaths (2%) and five late deaths (2.5%) in this group. Of the last 91 consecutive patients operated upon between Sept. 1, 1972 and June 30, 1980 none have died. Between September 1968 and June 1980, 14 patients with tetralogy of Fallot underwent a Waterston shunt. Their ages ranged from 2 days to 4 years. Six patients were younger than 35 days at the time of operation. There were two operative deaths in this group. The Waterston shunt carries a high risk and is reserved for the occasional patient who needs palliation during the first weeks of life and in whom the anatomy of the subclavian artery does not favour a good Blalock-Taussig shunt. The Blalock-Taussig operation is preferred because it is safe and gives good sustained clinical results. The mortality was much lower than previously reported. The growth of the pulmonary arteries was good in most patients. The Blalock shunt did not increase the pulmonary resistance and it did not influence the operative mortality.

Child↗
PubMed1981

Protection of the myocardial homograft. 1. The cooling bag.

Because severe cardiac insufficiency follows orthotopic heart transplantation, the authors have evaluated protection of the homograft provided by a cooling and isolating bag during the operative period of ischemia and subsequently its effect on cardiac function. In one group or four dogs hearts were transplanted without using hypothermia. In the second group, seven hearts were excised, immediately cooled by immersion in saline at 4 degrees C and orthotopically homotransplanted. In the third group, six hearts were immersed in saline and then isolated in a cooling bag until transplantation had been completed. Cardiac function in all animals was evaluated at rest, 3, 24 and 48 hours after operation. In group 1, lowering of the temperature was minimal and all animals died immediately after operation. In group 2, the myocardial temperature, which had been lowered to 13 degrees C by immersion, had risen to 25 degrees C after 17 minutes. In group 3, the myocardial temperature was maintained at 13 degrees C up to the time the aortic clamp was removed. Three hours after operation, the cardiac performance of group 3 was much better than that of group 3 was much better than that of group 2 as demonstrated by an increase of cardiac output (39%), stroke volume (44%), mean systolic ejection rate (25%), maximum systolic flow (28%), peak velocity (26%), maximum acceleration (20%), left ventricular power (32%) and left ventricular work (47%). In the following days, cardiac function of groups 2 and 3 improved and the disparity between then decreased. These results demonstrate that the cooling bag, while offering technical advantages, maintains profound hypothermia in the donor heart and substantially improves the performance of the homograft in the immediate postoperative phase.

Animals↗
PubMed1980

True diverticulum of the right ventricle: two cases associated with tetralogy of Fallot.

A true right ventricular diverticulum is a rare malformation consisting of an accessory ventricular outpouching communicating with the right ventricle through a muscular annulus and located at the right superior margin of the right ventricle. Its normal myocardial structure causes it to function as normal ventricle and in itself does not cause functional disturbances. In all reported instances, the malformation was associated with a ventricular septal defect and obstructive lesions of the right ventricular outflow tract. The 2 patients we describe had partial resection at the time of repair of tetralogy of Fallot and are doing well one and four years postoperatively.

Cardiac Catheterization↗
PubMed1980

[Aneurysm of the ductus arteriosus. Apropos of case operated on with success].

A 6 week old baby was operated on successfully for removal of an aneurysm of the ductus arteriosus. The aneurysm, absent at the age of 12 days, developed progressively during the closure of the ductus. The only suggestive symptom was a haemoptysis. The radiological appearances were characteristic. The authors discuss the physiopathology, clinical presentation and radiological appearances of this lesion.

Ductus Arteriosus, Patent↗