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PubMed1992

Energetics of the fibrillating ventricle.

We have proposed a new mechanical index, equivalent pressure-volume area (ePVA), as a measure of the total mechanical energy of a fibrillating ventricle. ePVA is an analogue of the pressure-volume area (PVA) of a contracting ventricle and the specific area surrounded by the horizontal pressure-volume line at the pressure of ventricular fibrillation (VF) and the end-systolic and end-diastolic pressure-volume relations in the beating state in the pressure-volume diagram. In the isolated, cross-circulated heart preparation, we obtained myocardial oxygen consumption (VO2) during VF and ePVA at various left ventricular volumes in the control, epinephrine, propranolol and hypothermia runs. ePVA was highly linearly correlated with VO2 in all runs (r = 0.95, 0.98, 0.96 and 0.90, respectively). We also determined equivalent heart rate (eHR) as an estimate of the contraction frequency of individual myocytes in a fibrillating ventricle from mechanically unloaded VO2 in beating and fibrillating states. Using both ePVA and eHR, VO2 during VF was estimated and correlated with directly measured VO2. Estimated VO2 almost agreed with measured VO2 in all runs. We conclude that ePVA is a primary determinant of VO2 during VF, and that VO2 of a fibrillating ventricle can be reasonably accounted for by the combination of ePVA and eHR. This paper is a review of our previous studies on the energetics of a fibrillating ventricle.

Animals↗
PubMed1992

Mechanical enhancement and myocardial oxygen saving by synchronized dynamic left ventricular compression.

Dynamic cardiomyoplasty with synchronously paced skeletal muscle grafts has recently been developed to augment the performance of impaired myocardium. This method has been reported effective to improve patients' general status and some hemodynamic parameters. It is unknown, however, how a systolic dynamic cardiac compression, as in dynamic cardiomyoplasty, affects left ventricular energetics. The purpose of this study was to characterize the effects of dynamic cardiac compression on the ventricle in terms of the pressure-volume relationship and myocardial oxygen consumption. In an isolated cross-circulated dog heart model, a dynamic cardiac compression device was set to directly compress the ventricle during systole. End-systolic pressure, contractility index (Emax), pressure-volume area, external mechanical work, coronary blood flow, and myocardial oxygen consumption were determined before and during dynamic cardiac compression. Dynamic cardiac compression significantly increased Emax. When end-diastolic and stroke volumes were fixed, end-systolic pressure, pressure-volume area, and external mechanical work significantly increased during dynamic cardiac compression while coronary blood flow and myocardial oxygen consumption remained unchanged. When end-systolic pressure was matched with the pre-dynamic cardiac compression control level by decreasing end-diastolic volume at a constant stroke volume so that external mechanical work under dynamic cardiac compression returned to the control level, both pressure-volume area and myocardial oxygen consumption significantly decreased. In contrast to a marked increase in myocardial oxygen consumption for a given increase in external mechanical work by either volume loading or dobutamine, dynamic cardiac compression did not increase myocardial oxygen consumption for the same increase in external mechanical work. Thus dynamic cardiac compression augments left ventricular pump function without increasing myocardial oxygen demand or compromising coronary blood flow.

Animals↗
PubMed1992

Cardiac preservation by continuous perfusion of the University of Wisconsin solution.

Recent studies have shown that the University of Wisconsin (UW) solution may be superior to standard solutions in preserving the isolated heart before transplantation. The authors compared the UW solution with a modified Krebs-Henseleit solution in a continuous hypothermic coronary perfusion model. Hearts from mongrel dogs were rapidly excised after hyperkalemic arrest with standard cardioplegia and were mounted in a perfusion apparatus for 24 hours. Twelve hearts were perfused with the Belzer UW solution (group 1), and 15 hearts were perfused with a modified Krebs-Henseleit solution (group 2). The hearts were transplanted in a cross-circulation model, and parameters of function (developed pressure [dP] and rate of pressure development [+/- dP/dt]) were measured. Mean (+/- SEM) developed pressure was 80 +/- 7 mm Hg in group 1 and 56 +/- 9 mm Hg in group 2 (p less than 0.05). The +dP/dt was 1433 +/- 126 mm Hg/s in group 1 and 843 +/- 154 mm Hg/s in group 2 (p less than 0.005), and the -dP/dt was 958 +/- 110 mm Hg/s in group 1 and 676 +/- 106 mm Hg/s in group 2 (p less than 0.05). The UW-preserved hearts also required fewer defibrillations (0.75 +/- 0.13) to establish a stable rhythm than the control hearts (5.87 +/- 2.07, p less than or equal to 0.02). There were no significant differences in weight gain, coronary resistance or creatine phosphokinase levels between the two groups. The authors conclude that the UW solution provides better preservation of function than a modified Krebs-Henseleit solution for continuous coronary perfusion.

Adenosine↗
PubMed2006

[Preload and ventricular lusitropism; logistic and monoexponential function fittings].

A logistic function has been found to fit the isovolumic left ventricular (LV) relaxation pressure curve and the isometric relaxation force curve of the papillary muscle much more precisely than the conventional monoexponential function. Therefore, the logistic time constant (tauL) has been proposed as a better index of the rate of cardiac relaxation or lusitropism than the conventional monoexponential time constant (tauE). Many investigators have reported that tauE changes with preloading. We analysed and compared the effect of LV volume (LVV) loading on both logistic and monoexponential fittings and their time constants of the isovolumic LV relaxation pressure curve in the excised, cross-circulated canine hearts. We found that the logistic fitting was superior to the monoexponential fitting at any LVV. LVV loading did not affect tauL at all but affected tauE slightly. The logistic fitting more reliably characterises the lusitropism than the monoexponential fitting, and tauL, serving as a more reliable ventricular lusitropism index, is independent of changes in LVV loading or the Frank-Starling effect.

Anesthesia↗
PubMed1991

[Central cardiovascular and renal effects of atrial natriuretic peptide].

In 54 anesthetized rats, the changes in arterial blood pressure, heart rate and/or urine volume, urinary sodium excretion were observed following intracarotid, intrathecal and intracerebroventricular (ICV) injection of atrial natriuretic peptide (ANP). The effects of ANP on the central actions of angiotensin II (AG II) were also examined. The results were as follows: (1) In the cross-circulation preparation of rat head, MAP of the recipient was unchanged and that of the donor was decreased in response to the administration of alpha-hANP (15 micrograms/kg) into the carotid artery of the recipient. (2) By injecting AP III (5 micrograms/kg) intrathecally, MAP, HR and urine volume (V) of the rats (n = 7) showed no change. (3) The ICV injection of AP III (20 micrograms/kg) did not result in changes in MAP, HR, and urinary sodium excretion (UNaV), but there was a transient and significant increase in V. (4) ICV injection of AG II (1 microgram/kg) resulted in an increase of MAP by 1.3 +/- 0.17 kPa (10 +/- 1.3 mmHg, n = 10, P less than 0.001), V by 106% (n = 6, P less than 0.01) and UNaV by 642% (P less than 0.01). (5) ICV injection of AP III 2 min prior to the injection of AG II by the same route, the central hypertensive effect induced by AG II was not affected, while the increments in V and UNaV were decreased significantly (P less than 0.05). The results indicate that (1) ANP is incapable of penetrating the blood-brain barrier owing to its large molecular size and therefore, the central mechanism is not involved in the hypotensive effect induced by intravenous injection of ANF and (2) the central diuretic and natriuretic actions of AG II may be markedly inhibited by ICV injection of ANP, thus indicating the existence of some central antagonistic interactions between AG II and ANP.

Angiotensin II↗
PubMed1991

Influence of intraalveolar oxygen concentration on lung preservation in a rabbit model.

We previously reported the use of an inexpensive screening model for lung preservation involving ventilation and perfusion of excised rabbit lungs after their preservation. We now have extended this model by perfusing the preserved lung in cross circulation with an anesthetized rabbit to permit stable reperfusion of the preserved lungs for 60 minutes. With this model we compared the results of lung preservation with the lungs inflated with nitrogen, room air, or 100% oxygen during 24 hours of hypothermic storage. Four groups of animals were studied: group 1, excision and immediate evaluation; group 2, inflation with room air and storage for 24 hours at 10 degrees C; group 3, same as group 2, with 100% oxygen for inflation during storage; group 4, same as group 2, with 100% nitrogen for inflation during storage. Assessment of the ex vivo perfused lung consisted of (1) blood gas analysis of inflow and outflow blood at 10-minute intervals; (2) continuous pulmonary artery and airway pressure monitoring; (3) measurement of pulmonary venous oxygen tension after 1 hour of reperfusion, with inflow oxygen tension adjusted to 15 mm Hg; (4) wet/dry weight ratio. We conclude that the paracorporeal circuit does not, in itself, cause lung injury over a 1-hour period; lungs preserved with nitrogen inflation rapidly became edematous and failed to function on reperfusion. Preservation with 100% oxygen inflation appears superior to inflation with room air.

Animals↗
PubMed1987

Arterial resistance vessels in primary hypertension--evidence for altered cellular Ca2+ metabolism.

The role of intracellular free Ca2+ in arterial smooth muscle was investigated in aortic smooth muscle cells from spontaneously hypertensive and normotensive rats, as well as in porcine aortic smooth muscle. Intracellular free Ca2+ in aortic smooth muscle from spontaneously hypertensive rats was elevated. Incubation of porcine aortic smooth muscle with plasma from essential hypertensive and normotensive subjects revealed a humoral factor in subjects with essential hypertension, which increased intracellular free Ca2+. Cross-circulation experiments between spontaneously hypertensive and normotensive rats demonstrated a transmission of hypertension to the normotensive animals as a result of a circulating hypertensive factor possibly produced in the kidneys and adrenals. The experiments suggest that vasoconstriction in primary hypertension may be caused by a humoral factor that increases intracellular free Ca2+ in arterial smooth muscle.

Animals↗
PubMed1989

[A case of recurrent internal carotid stenosis, after carotid endarterectomy, due to strangulation by scarring].

A case of recurrent internal carotid stenosis, one year after carotid endarterectomy, due to strangulation by scarring composed of digastric muscle, hypoglossal nerve and a branch of external carotid artery (ECA) is reported in this paper. A 34-year-old male suddenly became nauseated and developed right hemiplegia and dysphasia. He was admitted to a hospital, and the symptoms and signs improved gradually during a period of several weeks. A left carotid angiography, performed in another hospital, revealed a stenosis and wall irregularity around the highly-situated carotid bifurcation. He was transferred to our clinic with a view to being operated on. On admission, neurological examination disclosed a mild right motor weakness and motor dysphasia. A right carotid angiography revealed good cross circulation to the opposite. An EEG monitoring under the Matas test showed no outbreaks. With diagnosis of an embolism arising from carotid atheromatous plaque, a carotid endarterectomy was performed successfully. A postoperative angiography revealed good patency without stenosis nor wall irregularity around the carotid bifurcation. The postoperative and out-clinic condition was uneventful. However, one year after the operation, a left carotid angiography revealed recurrent internal carotid stenosis in a high degree. A second operation was performed and the operative findings showed an internal carotid stenosis due to strangulation by scarring composed of digastric muscle, hypoglossal nerve, a branch of ECA and connective tissue. The scarring was decompressed and a postoperative angiography revealed an improvement of the stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Myocardial energy metabolism in preserved heart: comparison of simple storage and hypothermic perfusion.

Isolated canine hearts were preserved for 24 hours by either simple hypothermic storage in Collins' M solution (group 1, n = 7) or hypothermic perfusion with oxygenated modified Krebs solution (group 2, n = 7), followed in both cases by reperfusion with cross circulation. Myocardial biopsies taken consecutively during preservation and after reperfusion were analyzed for high energy phosphates (adenosine triphosphate [ATP], adenosine diphosphate [ADP], adenosine monophosphate [AMP], and creatine phosphate), their catabolites (inosine), and lactate. In group 1, ATP decreased from 23.7 +/- 2.8 mumol/gm dry weight (mean +/- standard deviation) at 0 hours to 5.6 +/- 2.8 mumol/gm dry weight at the end of preservation. Creatine phosphate decreased and lactate increased significantly during 24 hours of preservation. The consumption rate of ATP appeared to have decreased after 18 hours of preservation. In group 2, ATP, creatine phosphate, and lactate remained at control levels during preservation. Coronary vascular resistance, however, increased significantly. After reperfusion functional measurements of the hearts in both groups did not vary significantly, despite the difference in myocardial ATP content (11.2 +/- 4.9 mumol/gm dry weight in group 1 and 17.9 +/- 3.9 mumol/gm dry weight in group 2; p less than 0.05). Simple hypothermic storage manifested a limitation in terms of energy store compared with hypothermic perfusion, whereas the latter appeared to have a risk of possible myocardial damage caused by the perfusion itself.

Animals↗
PubMed1977

[Hepatic coma--causes, recognition, treatment].

The name of the disease coma hepaticum is a collective notion for etiologically, pathologo-anatomically and biochemically different kinds of a failure of the function of the liver. A demarcation of different forms of the liver coma is necessary above all for prognostic and therapeutic reasons: hepatic disintegration coma, coma in hepatic failure, mixed coma, false hepatic coma, ferment block coma. Despite certain progress the therapeutic possibilities in hepatic coma cannot satisfy in recent years. Also the use of different, partly very expensive methods of the so-called liver substitute (exchange function and plasmapheresis, heterologous and homologous extracorporal liver perfusion, parasymbiotic crossed circulation, haemoperfusion with encapsulated activated charcoal, liver transplantation) up to now did not lead to a decisive improvement of the nearly infaust prognosis of the hepatic disintegration coma. Therefore preventing measures and careful control of endangered patients deserve particular attention.

Anti-Bacterial Agents↗
PubMed1985

[Resistance, exchange and capacitance vessels of the skeletal musculature in acute hypoxic hypoxia].

In cats under conditions of autoperfusion of hemodynamically isolated m. gastrocnemius, acute hypoxia (10% O2 in nitrogen) increased the precapillary and decreased the postcapillary resistance, reduced the capillary hydrostatic pressure and induced shifts of the capillary filtration coefficient (CFC) by 30% on the average. In cross-circulation performed for analysis of the neurogenic component in the vascular responses, analogous changes of the above parameters were revealed, the CFC decreasing, however. In denervated vascular bed of the m. gastrocnemius, the acute hypoxia decreased the precapillary and increased the postcapillary resistance, the hydrostatic pressure and the CFC increasing. In decentralized vessels of skeletal muscle, hypoxia induced prevalence of filtration while absorption of fluid prevailed in perfusion of the preparation with donor's arterial blood and in recipient's hypoxia.

Acute Disease↗
PubMed1985

[Pathophysiology of obstructive jaundice and its surgical problems].

Mitochondrial respiratory function, ketogenesis, collagen metabolism of the liver in rats, dogs and patients with obstructive jaundice were investigated. In animal experiments, it was revealed that mitochondrial respiratory function and ketogenesis decreased significantly with prolongation of biliary obstruction. Hepatic collagen content and its synthesis significantly increased in biliary obstruction. After relief of biliary obstruction in these dogs and patients, these functions and contents improved or returned to near normal levels according to the duration of biliary obstruction and period after relief. By steroid hormone and CoQ administration to jaundiced rats, improvement of mitochondrial function was obtained to some extent. Cross circulation between the jaundiced rat and normal one was performed and it was found that mitochondrial function in normal rat was decreased and that of jaundiced rat improved, especially in renal mitochondria. When major surgery is required in patients of biliary obstruction with severe jaundice, biliary drainage should be carried out first 4 to 6 weeks before major operation. Steroid or CoQ therapy and plasma exchange are also useful for these patients.

Animals↗
PubMed1978

[Evidence of an ileal hormone inhibiting pancreatic secretion (ACP anticholecystokinine peptide)].

The contact of long and medium chain fatty acids with the ileal mucosa inhibits basal or stimulated pancreatic protein secretion of Man, Dog, Cat and Rat. This inhibition is due to an inhibitory factor transmitted by cross-circulation. We isolated from partially purified extracts of Pig ileum a peptide which inhibits strongly volume and protein pancreatic output of the conscious Rat. We propose to call this factor ACP, anticholecystokinine peptide.

Animals↗
PubMedDate not supplied

[Acute hepatic insufficiency and the artificial liver].

The authors reviews some aspects related to hepatic encephalopathia and liver tissue regeneration, as well as criteria for prognosis of evolution and lethality of hepatic failure of the acute type. Methods of hepatic assistance include peritoneal dialysis, hemodialysis, exsanguinotransfusion, plasmapheresis, perfusion of isolated liver, crossed circulation, total washing of the organism, liver transplantation and artificial liver. The principles, the techniques and the materials used for the construction of an artificial liver are presented. Such materials include active charcoal, resins, enzymes, artificial cells of materials fixed upon active or passive supports presenting as plates, sheets, capillaries and dialysis membranes. The creation is suggested, of centers for hepatic depuration where prophylactic hepatic assistance could be provided, as well as the production of an artificial liver of the portable type for the treatment of chronic hepatic failure.

Acute Disease↗
PubMed1983

Changes in coronary blood flow produced by the coronary artery occlusion.

The influence of the occlusion of one coronary artery on coronary blood flow in an intact myocardium was investigated in narcotised dogs with open chest by using the crossed circulation method. Interruption of blood inflow to one of the branches of the left coronary artery under autoperfusion of the coronary bed led to a drop in the blood flow rate in the intact branch of the same artery, which was caused by decreased perfusion pressure. Stabilization of coronary perfusion pressure made it possible to detect the dilatatory reaction of the intact coronary bed to the occlusion of one of the coronary arteries. On the basis of an analysis of the dilatatory reaction, conclusions are drawn about the reflex nature of the observed phenomenon. The results of experiments with selective pharmacological blockade of both parts of the autonomous nervous system suggest that the afferent and efferent pathways run in the sympathetic nervous system.

Afferent Pathways↗
PubMed1984

Factors affecting the end-systolic pressure-volume relationship.

The end-systolic pressure-volume relationship (ESPVR) defines the systolic limits of cardiac performance. Using an isolated cross-circulated canine heart preparation, we examined the influence of afterload impedance changes, changes in coronary artery pressure (CAP), and regional ischemia on the ESPVR. We found that afterload impedance did not change the slope of the ESPVR but that increases in resistance and characteristic impedance did shift the relation slightly to the left. There was no change in the ESPVR with changes in CAP above a certain critical value. A decrease in CAP below this value caused a progressive decline in the slope of the ESPVR. With regional ischemia the ESPVR became nonlinear, and there was a near parallel downward shift of the ESPVR in the high-volume range. This shift was directly proportional to the extent of ischemic area. We conclude that an adequate measurement of the ESPVR demands at least three pressure-volume points to check for linearity and characterization of both the slope and volume intercept.

Animals↗
PubMed1980

Mechanism of the chronotropic effects of prostacyclin in the dog: comparison with the actions of prostaglandin E2.

The cardiovascular effects of prostaglandin (PG) I2 and E2 were investigated in the anesthetized dog and in the isolated blood perfused canine atrial preparation cross-circulated by the donor dog. When small doses of PGI2 (less than .01 microgram/kg) or PGE2 (1 microgram/kg) were injected into the jugular vein of the donor dog, there was a slight fall in blood pressure (5-10 mm Hg) and a slight degree of tachycardia (2-6 beats/min). However, larger doses of PGI2 (1-10 microgram/kg) or PGE2 (3-10 microgram/kg) produced hypotension that was associated with marked bradycardia. The bradycardia produced by both PGE2 and PGI2 in the donor dog was blocked by either atropine pretreatment or vagotomy and was inverted to tachycardia. The tachycardia was significantly suppressed by propranolol. Administration of PGI2 either to the donor dog or directly into the sinus node arterial cannula did not alter the atrial rate or developed tension in the isolated blood perfused atrial preparation. In contrast, when PGE2 was given in larger doses (10 microgram/kg) to the donor dog, the sinus rate and developed tension in the isolated atria were increased. This effect was markedly diminished after propranolol treatment. Administration of PGE2 (1-30 microgram) close-arterially into the sinus node artery produced positive chronotropic and inotropic effect which was not statistically significant. We conclude that PGI2 and PGE2 produce a negative chronotropic effect which is due to increased vagal activity and that these agents have no direct cardiac stimulatory effects in the anesthetized dog.

Animals↗
PubMed1978

[Experimental analysis of the humoral mechanism of microcirculatory disorders following thermal and mechanical traumatic shock in experiments on parabiotic rats].

In experiments on parabiotic rats with crossed circulation and separate innervation mechanical or burn trauma of one of the partners was followed by shock-like condition of the other one, and by microcirculatory changes in the mesentery typical of burn or traumatic shock. It shows that in burn shock, as well as in traumatic one, the detected changes in microcirculation are due to humoral, but not to neural factors.

Animals↗