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At least 595 records · Page 33Linked to original sources
PubMed1995

Short term effects of intra-arterial propionyl-L-carnitine on isolated canine hind-limbs.

Treatment with propionyl-L-carnitine has been shown to increase the walking capacity of patients with peripheral vascular disease, but the mechanisms responsible for the effect are unknown. To study the effects of propionyl-L-carnitine on musculocutaneous vascular beds and the related mechanisms, a preparation of constant-pressure blood-perfused dog hind-limb was used. Since the propionyl-L-carnitine solution had a pH less than 4 the contralateral limb simultaneously received acidified saline. The substances were injected into the perfused arteries in 2 minutes or in 20 minutes, and the cumulative dose of propionyl-L-carnitine was 20 mg/kg for each administration. The preparation was well suited for this study, because there were no major systemic effects of propionyl-L-carnitine, nor signs of cross-circulation between the isolated limbs. Propionyl-L-carnitine increased flow by 130% in 2 minute infusions and by 49% in 20 minute infusions. Acidified saline increased flow by 47% in 2 minute infusions and by 34% in 20 minute infusions. The difference between propionyl-L-carnitine and acidified saline was significant in 2 minute infusions. The 2 minute infusions of propionyl-L-carnitine increased venous PO2 by 34% and PCO2 by 22% while pH decreased by 0.07. The 20 minute infusions of propionyl-L-carnitine increased PO2 by 22% and PCO2 by 24% while pH decreased 0.10 units. Acidified saline increased only venous PO2 in 2 minute infusions (16%). Calculated oxygen consumption of the perfused limbs increased in 2 minute infusions of propionyl-L-carnitine, but not significantly. It was concluded that propionyl-L-carnitine has a direct vasodilator effect in musculocutaneous vascular beds at high doses and probably enhances tissue metabolism.

Animals↗
PubMed1995

[Traumatic carotid-cavernous aneurysm after removal of cancer of the upper jaw: a case report].

A case of a traumatic carotid-cavernous aneurysm after removal of cancer of the upper jaw was reported. A 63-year-old male complaining of massive epistaxis from the left nostril was admitted to our clinic. He had suffered from cancer of the left upper jaw and had been treated with radical operation. During the surgical procedure, massive bleeding which was considered to be from the left internal carotid artery, suddenly occurred. The hemorrhage was somehow controlled by packing with oxidized cellulose. He experienced recurrent massive epistaxis after admission. Cerebral angiograms revealed an anterior-medially projecting aneurysm arising from the cavernous portion of the left internal carotid artery. He had a good cross circulation from right to left on compression of the left carotid artery. This aneurysm at the carotid-cavernous portion was produced as a result of injury during an operation for cancer of the upper jaw. To prevent disastrous bleeding from the aneurysm, the aneurysm was then successfully treated by the trapping of extra-and intracranial carotid ligation in combination with left STA-MCA anastomosis. There was no recurrence of epistaxis after the operation. However, a low-grade fever persisted before operation and a blood culture showed MRSA sepsis after the operation. Intensive chemotherapy was performed for this MRSA sepsis, he died of the accompanying DIC. Although aneurysmal epistaxis following a severe closed head trauma is a well-known phenomenon, an iatrogenic carotid-cavernous aneurysm presenting with recurrent massive epistaxis is rare. Several comments were made about the iatrogenic carotid cavernous aneurysm, and the necessity of early diagnosis and treatment was emphasized.

Aneurysm, Ruptured↗
PubMed1993

Ventricular perspective on efficiency.

The heart has many efficiencies of different definitions, of which mechanical work efficiency is the most popular and conventional. We have proposed a method to quantify the total mechanical energy generated by ventricular contraction. This energy can be quantified as a specific area called "systolic pressure-volume area" or "PVA" in the ventricular pressure-volume diagram. In the left ventricle of excised, cross-circulated dog heart preparations, we found a closely linear relation between PVA and oxygen consumption (VO2) under various loading conditions in a stable contractile state (Emax). An enhanced contractility was accompanied by an elevation of the load-independent VO2-PVA relation in a parallel manner, where the elevation was proportional to Emax. The slope of the VO2-PVA relation represents the "oxygen cost of mechanical energy (or PVA)" and its reciprocal indicates the "contractile efficiency", i.e., the energy conversion efficiency from PVA-dependent VO2 to PVA. This efficiency was 40% on the average, independent of various inotropic interventions. The slope of the PVA-independent VO2-Emax relation represents the "oxygen cost of contractility (or Emax)". This cost was relatively constant for different inotropic interventions except for myocardial cooling and stunning. We considered the discrepancy between the stable contractile efficiency and the variable thermal economy of force generation and maintenance.

Animals↗
PubMedDate not supplied

Xipho-omphalopagous twins--separation in the newborn.

Male conjoined twins (thoraco-omphalopagous) were delivered by emergency Caesarean section performed in a full term, 3rd gravida who had presented in labour. On examination one of the twins had gross monstrosity and was threatening the survival of the better twin (twin A). The cannulation and dye studies through single umbilical vein demonstrated significant cross circulation across the connecting bridge. The vein was connected to liver of twin A. An emergency separation was performed to salvage the better twin.

Humans↗
PubMed1993

A historical perspective to current review of myocardial protection in cardiac operation.

In the discussion of the 1955 landmark study on the first series of open heart operation using the cross-circulation technique, Lillehei stated that, "The solution of many difficult problems in medicine has ultimately been simple and in most cases obvious once sufficient basic knowledge has been brought to bear on the problem." Indeed, a few surgeons have provided the guiding lights in the development of cardiac operation, but it is the acquisition of basic knowledge by thousands of surgeons and basic scientists that have contributed to its goals.

Cardiac Surgical Procedures↗
PubMed1993

[Pathological assessments of allografts after heart transplantation using a dog model--allograft vasculopathy].

The pathological findings of allografts after heart transplantation were assessed in long-term period using a dog model. Eight orthotopic heart transplantations were performed with cross-circulation method using a dog. Two dogs survived over 1 year after heart transplantation. One dog died due to cardiac rejection, and the another dog died due to infection at 14 months and 16 months after the transplantation, respectively. The coronary artery morphologic features were assessed in the allografts. The pathological findings showed fibrous intimal thickening with infiltration of lymphocytes and macrophages. And it was diffusely distributed to each area of transplanted heart. The stenosis of coronary lumen was significantly seen in middle size of coronary arteries which was from 100 microns to 50 microns. The characteristics of these findings in comparison with arteriosclerosis change were 1) rapid progression, 2) diffuse fibrous intimal thickening, 3) preserved internal elastic lamia. These findings might be important for treating this complication.

Animals↗
PubMedDate not supplied

[Acute fetofetal transfusion in dichorionic twins: a clinical case report].

Fetofetal transfusion is due to the twin to twin blood shunt caused by vascular anastomoses. It has been suggested that two types of FFT exist: a chronic form existing during pregnancy, and an acute form occurring only during parturition. Cross-circulation may be demonstrated in monochorionic as well as dichorionic placentas. However, such communications were found in 85-100% of monochorionic placentas, compared with one of 68 dichorionic fused placentas. Authors describe one case of acute feto-fetal transfusion in dichorionic twins.

Acute Disease↗
PubMed1993

Determinants of myocardial oxygen consumption in fibrillating dog hearts. Comparison between normothermia and hypothermia.

The purpose of the present study was to elucidate the mechanism of the difference in myocardial oxygen consumption between heating and fibrillating states during normothermia and hypothermia. In five isolated cross-circulated dog hearts, we measured left ventricular pressure at several ventricular volumes and myocardial oxygen consumption at V0 and V100, at which peak isovolumic pressures were zero and approximately 100 mm Hg, respectively, in beating and fibrillating states during normothermia and hypothermia (29 degrees C). As a measure of the total mechanical energy at V100, we obtained pressure-volume area in the beating state and equivalent pressure-volume area for fibrillation. We calculated equivalent heart rate as an estimate of the contraction frequency of individual myocytes in a fibrillating ventricle from myocardial oxygen consumption at V0 in the beating and fibrillating states. During normothermia, myocardial oxygen consumption per minute at V0 and V100 and myocardial oxygen consumption for mechanical purposes at V100 (myocardial oxygen consumption at V100-myocardial oxygen consumption at V0) were significantly higher during fibrillation than in the beating state. Equivalent pressure-volume area during fibrillation and pressure-volume area in the beating state at V100 were comparable, whereas equivalent heart rate during fibrillation was significantly higher than heart rate in the beating state. During hypothermia, myocardial oxygen consumption was comparable between beating and fibrillating states at V0, although myocardial oxygen consumption at V100 was slightly lower during fibrillation than in the beating state. Myocardial oxygen consumption for mechanical purposes during fibrillation was half of that in the beating state. Equivalent pressure-volume area was significantly smaller than pressure-volume area, whereas equivalent heart rate and heart rate were comparable. We conclude that during normothermia, higher myocardial oxygen consumption during fibrillation than in the beating state at V0 and V100 is attributable to the higher contraction frequency. During hypothermia the comparable myocardial oxygen consumption values at V0 are attributable to the comparable contraction frequencies, whereas slightly lower myocardial oxygen consumption during fibrillation at V100 is ascribed to the lower total mechanical energy.

Animals↗
PubMed1993

The effects of amrinone versus dobutamine on myocardial mechanics and energetics after hypothermic global ischemia.

The effects on the postischemic myocardium of amrinone and dobutamine were studied in canine hearts that underwent 90 minutes of hypothermic (10 degrees C) arrested ischemia. In an isolated heart preparation cross-circulated by a support dog, left ventricular pressure-volume loops were collected under a constant afterload based on a mock circulatory system and a range of preload conditions controlled by a computerized servo volume pump. Dobutamine (0, 5, 10, 15 micrograms/kg per minute) and amrinone (0, 0.75, 1.5, 3.0 mg/kg) were tested in this order based on the weights of the support dogs in eight experiments. Changes in intrinsic myocardial contractility were analyzed as percent increases in the preload recruitable stroke work area from baselines. Dobutamine exhibited significant dose-related increases in the preload recruitable stroke work area. Amrinone did not produce significant increases in preload recruitable stroke work area at 0.75 mg/kg; amrinone's inotropic effect was equivalent to dobutamine, 5 micrograms/kg per minute at 1.5 mg/kg, and at the maximum dose (3.0 mg/kg) it was equivalent to dobutamine, 10 micrograms/kg per minute. The myocardial energetic efficiency was determined from the analysis of the myocardial oxygen consumption-pressure volume area relationship. The y intercept represents the basal metabolic oxygen requirement of the unloaded beating heart, and the slope is inversely proportional to the rate of energy conversion for increasing loading conditions. Dobutamine significantly increased the y intercepts, but it had no effects on the slopes. These changes demonstrate reduced myocardial efficiencies that are consistent with previous reports. Amrinone (0.75 and 1.50 mg/kg) did not result in change of the y intercepts and the slopes of myocardial oxygen consumption-pressure-volume area relationship from baseline conditions. The y intercept was increased with amrinone (3.0 mg/kg), although still not significantly higher than baseline and not to the extents of the dobutamine group. Dobutamine did not have any primary effect on coronary resistance, while amrinone significantly reduced coronary resistance in all loading conditions at 1.5 and 3.0 mg/kg. This study demonstrates that the inotropic effects of amrinone tested under this constant afterload preparation were lower than those of dobutamine. Amrinone has a superior profile of myocardial efficiency on the postischemic myocardium since it does not produce the oxygen-wasting effects of the traditional inotropic agents such as the beta agonists. This benefit, together with amrinone's coronary dilating effects, critically improves the supply/demand ratio that may be of importance in certain clinical situations.

Amrinone↗
PubMed1996

Effects of levosimendan on myocardial contractility and oxygen consumption.

Levosimendan is hypothesized to be primarily a calcium sensitizer in vitro. Therefore, its inotropic action may be similar in both the normal and the congestive heart failure (CHF) state, and it may be associated with a decreased energetic cost of inotropism in vivo. To test these hypotheses, we gave levosimendan to cross-circulated isolated hearts from normal (n = 11) and CHF (n = 7, 4-week rapid pacing) dogs. Peak isovolumic left ventricular pressure at an end-diastolic pressure of 5 mm Hg (Pmax,5) measured by an intraventricular balloon was 120 +/- 15 mm Hg in normal dogs, and it was increased by approximately 40% in response to approximately 0.63 microM levosimendan. In CHF dogs, base-line Pmax,5 was only 60 +/- 12 mm Hg (P < .01 compared to normals), and approximately 8.4 microM levosimendan (P < .05) was required to increase Pmax,5 by approximately 40%. The inotropic actions were associated with increases in unloaded myocardial oxygen consumption by comparable amounts in normal and falling hearts. The blunted inotropic response in CHF and the energetic cost of inotropism were also comparable to those obtained with isoproterenol. In other studies, there was no significant inotropic action of levosimendan in Langendorff-perfused rat hearts (n = 5), and intracellular calcium concentration, estimated by macroinjected aequorin, in ferret hearts (n = 2) increased dose-dependently. These findings suggest that inotropic actions of levosimendan in vivo may be mediated in part by factors other than calcium sensitization.

Animals↗
PubMedDate not supplied

[Effect of apressin on the mechanism regulating vascular tone].

Acute experiments with anesthetized and decerebrate cats brought evidence that in a dose of 1 mg/kg apressin first increases by 50 per cent the centrogenically-produced pressor vascular reactions and then (30-60 min thereafter) suppresses pressor responses. Apressin (in a dose of 3-5 mg/kg) appreciably weakens the intensity of the pressor vascular reactions and increases the efferent outflow in the renal nerve. In doses of 1-10 mg/kg it does not affect the transmission of excitation in the superior cervical sympathic ganglion and in the solar plexus nodes. In tests with the crossed circulation apressin in doses of 1 and 5 mg/kg produces a marked depression of vascular reactions and a drop of the perfusion pressure in the vessels of the hind extremity perfused with the autoblood and a rising intensity of these reactions along with a greater resistance of the hind extremity vessels, perfused with the donor's blood.

Animals↗
PubMed1997

[A case of traumatic extracranial internal carotid artery dissecting aneurysm treated by proximal ligation and STA-MCA bypass].

We present a case with the traumatic extracranial internal carotid artery dissecting aneurysm. A 21-year-old man was involved in a motorcycle accident, resulting in multiple injuries but no apparent head and neck injuries. Head CT was normal on his admission. He was discharged from his local hospital 3 weeks after the accident without any neurological deficits. Five weeks after the accident, he suddenly presented with a motor aphasia and a right hemiparesis. CT and MRI showed infarctions in the left para-Sylvian and the left angular areas. Angiography showed a left extracranial carotid artery dissecting aneurysm at the level of C1 vertebral arch. The patient was initially managed by an anticoagulant agent, but he suffered from another transient ischemic attack due to distal embolism from the aneurysm. Balloon occlusion test of the left ICA was performed under monitoring EEG, SEP. Mean stump pressure (MSP) revealed 60 mmHg. and MSP/Mean systematic blood pressure revealed 67%. We judged that the left ICA ligation was a safe method to treat this patient, however, considering the patient's age and the side of the lesion, left STA-MICA bypass and ligation of the left ICA were carried out in one stage. Postoperatively, the patient did not show any cerebral ischemic complications and angiography showed disappearance of the aneurysm and patency of the bypass. The left MCA territories were filled well by cross circulation and the bypass.

Accidents, Traffic↗
PubMed1996

Extracranial carotid artery aneurysms.

This article reviews the etiology, clinical manifestations, operative techniques, and results of management of fourteen cases of extracranial carotid artery aneurysms, operated upon in our institution between September 1990 and August 1994. Except for one, they were elective operations. Aneurysmectomy with restoration of continuity by direct anastomosis was done in four cases, an autogenous saphenous vein graft was performed in one, and prosthetic grafts (Dacron) in three. Local conditions precluded restoration of arterial continuity in two cases. Two patients underwent exclusion and bypass graft, and one underwent exclusion only. Ligation was resorted to in one patient, who was subjected to emergency surgery due to rupture of the aneurysm. A temporary, intra-operative, extraluminal carotid artery shunt was used in only one patient, as all the others had angiographic evidence of satisfactory cerebral cross-circulation. Two patients developed transient, neurological deficits in the post-operative period. There was no mortality. We conclude that aneurysms of the extracranial carotid arteries can be operated on with minimal morbidity and no mortality. Operative management is the treatment of choice because of their potential neurological complications, if left untreated.

Adult↗
PubMed1997

Mechanoenergetic effect of pimobendan in failing dog hearts.

The effect of cardiotonic drugs with a calcium-sensitizing effect (Ca2+ sensitizers) on cardiac mechanoenergetics in the failing heart is not fully understood. Accordingly, we measured left ventricular (LV) contractility (Emax) and the relation between myocardial oxygen consumption (VO2) and pressure-volume area (PVA; a measure of LV total mechanical energy) before and during enhancement of contractility by infusion of dobutamine (DOB) or pimobendan (PIMO) in six cross-circulated hearts isolated from pacing-induced heart failure (FL) dogs, and compared the results with those reported in normal hearts (NL, n = 12). Although the baseline Emax was much lower in FL dogs than in NL dogs (P < 0.01), DOB and PIMO comparably enhanced Emax in the FL dogs. The O2 cost of contractility, defined as the increase in unloaded VO2 at zero PVA divided by the increase in Emax, obtained during an enhancement of contractility with DOB, was significantly higher in FL dogs than in NL dogs, suggesting that a larger amount of O2 is consumed during Ca2+ cycling with DOB in FL dogs. In contrast, the O2 cost of contractility with PIMO was similar between FL and NL dogs. Furthermore, the VO2 per minute was significantly higher with DOB (P < 0.05) than with PIMO partly because of an excessive positive chronotropic effect of DOB. We concluded that (1) PIMO exerts a positive inotropic effect comparable to that of DOB in both NL and FL dogs; (2) the O2 cost of contractility with DOB is higher in FL dogs than in NL dogs; and (3) PIMO has a relative O2-saving effect compared with DOB in FL dogs.

Animals↗
PubMed1998

Open hearts. The origins of direct-vision intracardiac surgery.

Only 50 years ago, operating under direct vision within the walls of the living human heart appeared to be a surgical problem with no great hope of solution. However, technologic advances soon provided the necessary tools, and a safe, reliable, and practical technique of performing surgery within the open heart evolved in a series of stages. First, W.G. Bigelow espoused applied hypothermia as a means of protecting the vital organs during direct cardiac repair--a technique that F.J. Lewis then applied in correcting an atrial septal defect under direct vision. This was followed by C.W. Lillehei's introduction and application of controlled cross-circulation, which enabled the correction of more complex cardiac lesions. Finally, the efforts of J.H. Gibbon and J.W. Kirklin led to the creation of a reliable cardiopulmonary bypass apparatus, which enabled the many subsequent achievements well recognized in the history of surgery.

Canada↗
PubMed1998

Effects of brain death on myocardial function and ischemic tolerance of potential donor hearts.

BACKGROUND: An increasing number of experimental and clinical studies reports hemodynamic instability in the donor organism after brain death. However, the relative importance of brain death-related cardiac dysfunction on posttransplantation cardiac function and the reversibility of the observed changes remain controversial. In this study a load-independent analysis of cardiac function after brain death was performed. Special interest was focused on a possible interactive influence of brain death and cardiac preservation on postischemic cardiac function. METHODS: In 12 anesthetized dogs, brain death was induced by inflation of a subdural balloon; 12 sham-operated animals served as control subjects. After a 2-hour observation in situ, the hearts were explanted and perfused parabiotically either immediately or after hypothermic ischemic preservation (4 hours, 4 degrees C). Heart rate, cardiac output, left ventricular pressure, the maximum of left ventricular pressure development and aortic pressure were measured in situ. In addition, the slope of the end-systolic pressure-volume relationship, coronary blood flow, and myocardial oxygen consumption were estimated in the cross-circulated hearts. RESULTS: In spite of a brain death-associated hemodynamic deterioration in situ (expressed as low mean aortic pressure and significant decrease of maximal dP/dt), myocardial function was similar to control after explantation, if assessed ex vivo. Furthermore, after hypothermic ischemic preservation and reperfusion, complete functional recovery of control and brain-dead hearts could be observed. CONCLUSIONS: These data indicate that hemodynamic instability after brain death may rather reflect altered loading conditions than irreversible myocardial damage or primary cardiac dysfunction. Furthermore, there is no evidence for a brain death-related impairment of ischemic tolerance.

Animals↗
PubMed1976

[Critical study of electric activity of the small intestine in the dog].

Thanks to a cross-circulation, the authors caused to survive in the abdomen of a sacrificed dog, the whole of the small intestine, the motor activity of which was analysed by electro-enterography. This experimental preparation thus eliminates polygraphic recordings of all potential variations outside the small intestine, e.g. stomach, colon, diaphragm, muscle, myocardium. One thus obtains very pure tracings of the variations of potential originating in the small intestine, recorded from bipolar serous intestinal electrodes, they show the activity of the small intestine, consisting of a permanent basal electric rhythm on which are grafted spikes contemporary of motor phenomena. In the abdominal skin there were recorded only a cutaneous slow wave which was contemporary with the deep motor phenomena.

Animals↗
PubMed1988

Bioassay by cross-perfusion for circulating inotropic factor in hypertension.

To study inotropic effects of blood from one-kidney, one-clip (1K,1C) rats with early (less than 7 days) or chronic (greater than 4 wk) benign hypertension, we assessed arteriolar resistance and norepinephrine (NE) responses in vascularly isolated, innervated assay hindlimb vascular beds of alpha-chloralose-anesthetized, normal male recipient rats. Hindlimbs were cross-perfused (2 ml/min) with blood from anesthetized donor rats with limb outflow returned to the donor rat. Perfusion pressure was monitored. Complete NE (injected intra-arterially) dose-response curves in limbs perfused with donor blood from nine early 1K,1C rats, compared with nine appropriate normotensive control donor rats, indicated unchanged thresholds, 50% effective doses, and maximal responses. Curves in limbs perfused with blood from 10 chronic 1K,1C, compared with 10 appropriate controls, suggested small (P less than 0.02) leftward shifts. Decreases (P less than 0.01) in maximal responses were also observed. Limb resting resistance and minimal resistance (sodium nitroprusside) did not rise, even after 4-5 h of cross-perfusion. These results provide no evidence in early 1K,1C and little evidence in chronic 1K,1C that humoral factors, including ouabainlike inhibitors, evoke physiologically significant inotropic effects in arterioles in vivo.

Algorithms↗