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PubMed1975

Effect of intraventricular administration of noradrenaline on water diuresis in goats.

Duriing water diuresis in conscious goats, noradrenaline (NA), its antagonists phentolamine, phenoxybenzamine and propranolol and also atropine were administered into the 3rd ventricle. The subsequent effects on water diuresis and on the excretion rates of Na+, K+ and Cl- were investigated. Infusion of NA into the 3rd ventricle induced a strong and significant antidiuretic response and a decrease in the Na+ : K+ excretion ratio; these effects were dose-dependent. High doses of NA produced a significant increase in urinary K+ excretion. Similar results were observed after i.v. administration of arginine-vasopressin. Pretreatment with phentolamine injected into the 3rd ventricle produced a dose-dependent inhibition of the NA-induced antidiuretic effects. Phenoxybenzamine also blocked the response to NA but a dose-response relationship was not apparent. Atropine and propranolol did not block the response to NA.

Animals↗
PubMed1984

Effect of pneumothorax-induced systemic blood pressure alterations on the cerebral circulation in newborn dogs.

Pneumothorax has been associated with intraventricular hemorrhage in premature infants, although the mechanism for this relationship is not clear. Because alterations in cerebral blood flow are believed to be important in the pathogenesis of intraventricular hemorrhage, the effect of induced pneumothorax and subsequent evacuation on the cerebral circulation in 16 newborn dogs was evaluated. Continuous Doppler ultrasound was used to monitor changes in cerebral blood velocity. Pneumothorax was induced by slow infusion (5 cc/kg/min) or rapid infusion (5 to 10 seconds) of air to reduce mean arterial blood pressure to half of base-line levels. Both methods of pneumothorax induction resulted in significant elevations of central venous pressure and intrapleural pressure, whereas mean arterial blood pressure and cerebral blood velocity decreased significantly. In each group, the pneumothorax was evacuated either by slow withdrawal of air (10 cc/kg/min) or as rapidly as possible. Rapid evacuation of air resulted in an immediate increase in mean arterial blood pressure and cerebral blood velocity to supranormal levels. Slow evacuation led to a more gradual normalization of mean arterial blood pressure and cerebral blood velocity. It is suggested that the precipitous increases in mean arterial blood pressure and cerebral blood velocity following rapid evacuation of a tension pneumothorax may account for the observed association between pneumothorax and intraventricular hemorrhage in premature infants.

Animals↗
PubMed1983

Cerebrospinal fluid and plasma pharmacokinetics of high doses of 1-beta-D-arabinofuranosylcytosine in nonhuman primates.

The pharmacokinetics of 1-beta-D-arabinofuranosylcytosine (ara-C) in plasma, cerebrospinal fluid (CSF), and urine was studied in nonhuman primates. Conventional and high-dose schedules of ara-C were administered i.v. and intraventricularly through indwelling Ommaya reservoirs. ara-C and its metabolite 1-beta-D-arabinofuranosyluracil (ara-U) were measured by high-pressure liquid chromatography. Due to rapid peripheral deamination (230 nm ara-C/hr/ml plasma), the half-life of ara-C in plasma after a 140-mg/kg i.v. 1-hr infusion was short (3.7 min). Peak plasma concentrations of ara-C, ranging between less than 0.1 and 49 micrograms/ml, were dose dependent (ara-C, 15 to 140 mg/kg). Under these conditions, ara-C was undetectable in CSF. About 53% of the administered dose (140 mg/kg) was excreted in urine during the first 5 hr mostly as ara-U. Intraventricular administration of 50 and 250 mg of ara-C resulted in peak lumbar CSF levels of 435 and 2235 micrograms/ml, respectively, at about 155 and 80 min postinjection. Concomitant ara-U levels were one-tenth of those of ara-C and increased progressively, suggesting deamination of the drug in the central nervous system. The half-life of ara-C in CSF ranged between 50 and 60 min. Administration of 50 mg of ara-U intraventricularly resulted in peak lumbar ara-U levels of 595 micrograms/ml at about 180 min with a prolonged clearance. Concomitant plasma levels throughout the study were less than 0.1 micrograms/ml, suggesting slower equilibrium. No hematological or nervous system toxicity was observed during these studies. The clinical implications of these findings are discussed.

Animals↗
PubMed2001

Posterior fossa decompression and clot evacuation for fourth ventricle hemorrhage after aneurysmal rupture: case report.

OBJECTIVE AND IMPORTANCE: Massive intraventricular hemorrhage due to aneurysmal rupture is associated with a dismal prognosis. An intraventricular clot causing fourth ventricle dilation can cause compression to the brainstem similar to other posterior fossa masses such as cerebellar hemorrhage or infarction. The presence of fourth ventricle dilation carries a very high risk of death within 48 hours. Neither ventricular drainage nor fibrinolytic infusion has been successful in eliminating clots of the fourth ventricle. Posterior fossa decompression and direct evacuation of the clot could have good results in relieving brainstem compression caused by the clot. CLINICAL PRESENTATION: A 45-year-old woman was admitted to our intensive care unit after experiencing an aneurysmal subarachnoid hemorrhage. The neurological examination at admission revealed that she was in Grade V according to the World Federation of Neurological Surgeons grading system, but brainstem reflexes were present. Computed tomographic scanning revealed a massive intraventricular hemorrhage, with fourth ventricle dilation caused by an intraventricular clot. Bilateral external ventricular drains were placed to relieve elevated intracranial pressure. Cerebral angiography revealed a 1-cm basilar tip aneurysm, which was embolized with Guglielmi detachable coils (Boston Scientific, Boston, MA) during the same procedure. INTERVENTION: Given the patient's poor neurological condition, it was decided that brainstem compression should be relieved. A posterior fossa decompressive craniectomy was performed immediately after coil therapy, with direct evacuation of the intraventricular clot. The patient experienced a clear improvement in the level of consciousness and has achieved a good neurological result at early follow-up. CONCLUSION: Dilation of the fourth ventricle by an intraventricular clot is a sign of brainstem compression that can be relieved by posterior fossa decompression and direct clot evacuation.

Aneurysm, Ruptured↗
PubMed1988

[Hemodynamic effects on intravenous propafenone in hypertrophic myocardiopathy].

None of the medical treatments of hypertrophic cardiomyopathy is perfect. In the present study conducted on 11 patients with hypertrophic cardiomyopathy in whom the usual treatments were either ineffective or badly tolerated, the haemodynamic effects of propafenone administered intravenously were investigated. The drug was injected centrally in doses of 2 mg/kg over 10 minutes, then by continuous intravenous infusion of 1.5 mg/min during 30 minutes. Various parameters were recorded before and after propafenone treatment by right and left cardiac catheterization. This anti-arrhythmic drug, which has beta-blocking and amiodarone-like properties, reduced left intraventricular obstruction but had no beneficial effect on diastolic function. The baseline and induced left intraventricular gradients were reduced from 30.4 to 17.7 mmHg and from 74 to 43 mmHg respectively. Diastolic function values showed a fall in dp/dt min from 1470 to 1307 mm/sec and an increase in T value from 0.066 to 0.084. The use of propafenone in hypertrophic cardiomyopathy must be accurately determined by long-term oral studies.

Adolescent↗
PubMed2006

Hydrocephalus in a rat model of intraventricular hemorrhage.

The aims of the current study were 1) to establish an adult rat model of intraventricular hemorrhage (IVH) and post-hemorrhagic ventricular dilatation, and 2) to examine the role of alterations in cerebrospinal fluid (CSF) drainage and parenchymal injury in that dilatation. Rats underwent infusion of 200 microl of autologous blood over 15 minutes. The rats were used to measure hematoma mass, ventricular dilatation, and cortical mantle volume (with T2 imaging), resistance to CSF absorption, and brain edema (as a marker of brain injury). IVH resulted in ventricular dilatation peaking at day 2 but persisting for at least 8 weeks. Although there was an increased resistance to CSF absorption at 3 days, it returned to normal at day 7. Long-term ventricular dilatation was not associated with an alteration in cortical mantle volume, although there was evidence of cortical damage (edema). It is possible that initial ventricular distension (due to the hematoma and the impaired CSF drainage) in combination with periventricular white matter damage results in structural changes that prevent total recoil once the hematoma has resolved and CSF drainage is normalized, leading to long-term hydrocephalus.

Animals↗
PubMed2004

Effects of morphine analgesia in ventilated preterm neonates: primary outcomes from the NEOPAIN randomised trial.

BACKGROUND: Opioid analgesia is commonly used during neonatal intensive care. We undertook the Neurologic Outcomes and Pre-emptive Analgesia in Neonates (NEOPAIN) trial to investigate whether pre-emptive morphine analgesia decreases the rate of a composite primary outcome of neonatal death, severe intraventricular haemorrhage (IVH), and periventricular leucomalacia (PVL) in preterm neonates. METHODS: Ventilated preterm neonates (n=898) from 16 centres were randomly assigned masked placebo (n=449) or morphine (n=449) infusions. After a loading dose (100 microg/kg), morphine infusions (23-26 weeks of gestation 10 microg kg(-1) h(-1); 27-29 weeks 20 microg kg(-1) h(-1); 30-32 weeks 30 microg kg(-1) h(-1)) were continued as long as clinically justified (maximum 14 days). Open-label morphine could be given on clinical judgment (placebo group 242/443 [54.6%], morphine group 202/446 [45.3%]). Analyses were by intention to treat. FINDINGS: Baseline variables were similar in the randomised groups. The placebo and morphine groups had similar rates of the composite outcome (105/408 [26%] vs 115/419 [27%]), neonatal death (47/449 [11%] vs 58/449 [13%]), severe IVH (46/429 [11%] vs 55/411 [13%]), and PVL (34/367 [9%] vs 27/367 [7%]). For neonates who were not given open-label morphine, rates of the composite outcome (53/225 [24%] vs 27/179 [15%], p=0.0338) and severe IVH (19/219 [9%] vs 6/189 [3%], p=0.0209) were higher in the morphine group than the placebo group. Placebo-group neonates receiving open-label morphine had worse rates of the composite outcome than those not receiving open-label morphine (78/228 [34%] vs 27/179 [15%], p<0.0001). Morphine-group neonates receiving open-label morphine were more likely to develop severe IVH (36/190 [19%] vs 19/219 [9%], p=0.0024). INTERPRETATION: Pre-emptive morphine infusions did not reduce the frequency of severe IVH, PVL, or death in ventilated preterm neonates, but intermittent boluses of open-label morphine were associated with an increased rate of the composite outcome. The morphine doses used in this study decrease clinical signs of pain but can cause significant adverse effects in ventilated preterm neonates.

Analgesics, Opioid↗
PubMed2002

Quantitation of basal dyssynchrony and acute resynchronization from left or biventricular pacing by novel echo-contrast variability imaging.

OBJECTIVES: This study sought to test a novel echocardiographic method based on contrast variability imaging (CVI), to quantify cardiac dyssynchrony and magnitude of resynchronization achieved by left ventricular (LV) and biventricular (BiV) pacing therapy. BACKGROUND: Left ventricular or BiV pacing is a promising new therapy for patients with heart failure and intraventricular conduction delay. However, precise quantitation of the extent of resynchronization achieved remains scant. METHODS: Ten patients treated with BiV or LV pacing therapy were studied. Echo-contrast was infused slowly, and gated images were acquired before and during contrast appearance. The temporally normalized variance derived from 30 to 50 sequential beats was determined at each pixel to yield the CVI image-displaying improved wall delineation. Systolic regional fractional area of radial sectors was calculated with active and temporarily suspended (AAI) pacing. All analyses were performed blinded to both patient and treatment. RESULTS: Pacing increased septal inward motion from -20.4 +/- 9.6% to -30.5 +/- 14.0%, whereas lateral wall motion occurred earlier with no net magnitude change. Both spatial and temporal dyssynchrony in the LV declined nearly 40% with LV or BiV pacing (p < or = 0.001), and this correlated with increasing ejection fraction (31% to 39%; p < 0.02; p < 0.004 for correlation with dyssynchrony). CONCLUSIONS: The new imaging and regional dyssynchrony analysis methods provide quantitative assessment of resynchronization analogous to that previously obtained only by tagged magnetic resonance imaging. This could provide a useful noninvasive method for both identifying candidates and following long-term therapy.

Cardiac Pacing, Artificial↗
PubMed1975

Electrophysiological effects of the antiarrhythmic agent QX-572 in the human heart with special reference to rate-induced changes in effective refractory periods.

The antiarrhythmic agent, N,N-bis(phenylcarbamoylmethyl)dimethylammonium chloride (QX-572) 8 mg/kg body weight produced a decreased conduction time through the atrioventricular node but did not influence intra-atrial or intraventricular conduction. Effective refractory periods of the atrium, the atrioventricular conduction system, and the ventricle were shortened by the drug. The observed effects were present at the end of drug infusion but had disapnerbd 30 min later. The probable explanation is an increased sympathetic tone induced by QX-572.

Adult↗
PubMed1994

Electrophysiologic Changes in the Human Heart Produced by Enalaprilat (Angiotensin-Converting Enzyme Inhibitor).

Several trials have showed that angiotensin-converting enzyme inhibitors possess some extent of antiarrhythmic properties. To evaluate the effects of Enalaprilat on His bundle recording, patients undergoing diagnostic coronary angiogram due to angina pectoris and a positive thallium exercise test subsequently underwent His bundle electrogram. A double-blind crossover protocol was used with conduction velocity measurements at baseline and after saline (placebo) and Enalaprilat 2.5 mg intravenously. There were no significant changes in heart rate (64 plus minus 9 versus 65 plus minus 11 versus 65 plus minus to beats min(minus sign1)) at baseline, after saline and enalaprilat infusion, respectively, mean blood pressure (97 plus minus 11 versus 94 plus minus 10 versus 94 plus minus 7 mm Hg, respectively), atrioventricular conduction time (100 plus minus 20 versus 100 plus minus versus 100 plus minus 20 versus 100 plus minus ms), and His--Purkinje (HV) conduction time (40 plus minus 12 versus 40 plus minus 13 versus 40 plus minus 12 ms). Ventricular activity duration was 110 plus minus 11 ms at baseline, 110 plus minus 10 ms after saline infusion (p = NS), and 88 plus minus 13 ms after Enalaprilat administration (p < 0.001). Angiotensin-converting enzyme inhibition appears to produce significant reduction in ventricular activity duration (increase in intraventricular conduction velocity).

Journal Article↗
PubMed1983

Factors influencing exit of substances from cerebrospinal fluid into deep cervical lymph of the rabbit.

Experiments have been made to determine the main route by which radio-iodinated albumin reaches deep cervical lymph from cerebrospinal fluid (c.s.f.) in the anaesthetized rabbit. Other factors, influencing drainage through this pathway, have been investigated. After single injection of [125I]albumin into a lateral ventricle of control rabbits, a mean of 14.8% of the radioactivity lost from brain-c.s.f. was recovered during 6 hr in the lymph of the cannulated jugular trunk of one side. Injection of kaolin into the olfactory fossa or sealing of the cribriform plate with cyanoacrylate glue reduced the recovery of [125I]albumin to 3.3% and 1.9% respectively at 2-3 weeks after the procedure designed to block the cribriform plate. This confirms the traditional view that the major connexions between c.s.f. and deep cervical lymph is via prolongations of subarachnoid space around the olfactory nerves, leading into the interstitial spaces of the nasal submucosa. The dense lymphatic plexus in this tissue is known to drain into the retropharyngeal (deep cervical) lymph nodes. Constant infusion of artificial c.s.f. into a lateral ventricle at 10 microliters/min or 30 microliters/min, in order to approximately double or quadruple flow through the system respectively, decreased the recovery of intraventricular [125I]albumin to 8.1% and 6.9% respectively. It also appeared that the increased c.s.f. pressures induced forced relatively more radioactivity from inside the skull into the c.s.f. spaces of the spinal cord. Maintaining the rabbit prone but at 20 degrees from the horizontal caused recoveries of [125I]albumin in lymph of 17.6% (head-up position and 6.6% (head-down). The amounts of radioactivity in nose and spinal cord markedly increased and decreased respectively in the head-down position. They changed in the opposite directions in the head-up position. The amounts of [51Cr]EDTA, [125I]metrizamide and [14C]inulin in deep cervical lymph were negligible after intraventricular injection. Estimations of the ratio of [51Cr]EDTA/[125I]albumin in various tissues on the pathway into lymph, together with measurements of arterio-venous fluxes across the retropharyngeal nodes, indicate that [51Cr]EDTA passed from c.s.f./lymph into blood within both the nose and the lymph nodes.

Albumins↗
PubMed1989

Functional relevance of the microheterogeneity of active renin.

We previously demonstrated the presence of six active forms of renin in rats, based on their isoelectric points (pI). Intravenous or intraventricular injections yielded different renal effects with the different forms. Additional work is presented supporting the hypothesis that these forms are functionally different. Renin form 2 (pI = 5.7), form 4 (pI = 5.2) or form 6 (pI = 4.8) was infused intravenously (IV) in Spague-Dawley rats. The total renin infused over 30 minutes was the amount that could generate 1000 ng angiotensin I (Ang I)/h/100g body weight. Arterial blood pressure, urine volume, sodium, and potassium excretion were determined at 15-minute intervals. Plasma renin activity (PRA) and plasma aldosterone concentrations were measured 45 minutes after the start of infusion of renin forms. Infusion of renin form 4 increased urine volume and sodium excretion significantly. Renin forms 2 and 6 were without effect on renal excretion in spite of the fact that the same activity was infused. Both PRA and aldosterone concentrations after renin infusions were similar for all groups. Nonrenin renal protein with the same pI as form 4 was used as a control. This preparation was inactive and implies that our data with renin form 4 were not the result of contamination with a nonrenin protein having a pI of 5.2. In addition, the urinary responses could not be attributable to change in renal perfusion pressure as arterial blood pressure was not altered. These data support the hypothesis that there are functional differences among the different renin forms.

Animals↗
PubMed1976

Response of tanycytes of rat median eminence to intraventricular administration of colchicine and vinblastine.

The effects of colchicine and vinblastine on tanycytes of the rat median eminence have been studied using the electron microscope. Colchicine and vinblastine were administered by intraventricular cannulation into the third ventricle and demonstrated distinct morphological effects on tanycyte microtubules. Highest drug doses administered were 50.0 mug in 5.0 mul of saline initially, followed by an additional 50.0 mug of these agents infused in a volume of 13.0 mul saline over an hour. Colchicine treatment resulted in the formation of large crystalloids within tanycytes, coincident with the disappearance of microtubules, all along the ventricular surface. Nonetheless the tanycytes appeared able to maintain a continuous, tight lining, as in controls, although some crystalloids were observed beneath the ventricular surface, either within tanycyte processes or within neuronal processes. Vinblastine treatment also resulted in the formation of identical crystalloids but at highest doses thoroughly destroyed the tanycyte lining of the median eminence and exposed cellular elements below the surface to the drug. Portal capillaries approaching the ventricular surface were generally free of any signs of drug response to either colchicine or vinblastine.

Animals↗
PubMed1989

Antagonism of NMDA receptors impairs acquisition but not retention of olfactory memory.

Prompted by evidence pointing to a key role of the N-methyl-D-aspartate (NMDA) receptor system in the induction of long-term potentiation and possibly in the formation of some types of memory, we examined the effect of chronic intraventricular administration of D-amino-phosphono-valeric acid (AP5), a competitive NMDA receptor antagonist, on olfactory discrimination and avoidance learning. These two tasks were selected because they are affected to very different degrees by damage to the hippocampus and other telencephalic structures rich in NMDA receptors. Twenty rats previously trained to solve a series of discriminations between two simultaneously presented odors were infused with either 20 mM D-AP5 or saline (n = 10 per group) for 14 days. An important and unusual feature of the paradigm was that it permitted a comparison of drug effects on acquisition of new discriminations versus retention of old ones. Animals treated with AP5 made significantly more errors than did saline controls in acquiring discriminations between low-intensity odors presented with long intertrial intervals (ITIs). However, no deficit was observed when short ITIs (less than 2 min) or strong odors were used. Animals treated with AP5 had no difficulty in recognizing odors on which they were trained before administration of the drug. After exhaustion of the pumps, performance of the AP5 group was indistinguishable from that of the control group. One-way active avoidance learning was not affected by chronic infusion of AP5. Several possibilities are discussed that could account for the selective olfactory learning deficit.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-5-phosphonovalerate↗
PubMed1991

Adverse interaction between bupivacaine and halothane on ventricular contractile force and intraventricular conduction in the dog.

Regional anesthesia with bupivacaine in pediatric patients is often accompanied by light levels of halothane general anesthesia. To determine the potential cardiotoxicity of these two drugs when used together, we defined the interaction between moderate plasma bupivacaine concentrations (1270-1760 ng/mL) and halothane (end-tidal concentrations, 0.5%-1.0%) on ventricular contractility and conduction in 22 closed-chest dogs anesthetized with chloralose. Bupivacaine alone (1-mg/kg intravenous bolus plus a 0.1-mg.kg-1.min-1 constant rate infusion) resulted in significant increases in ventricular conduction time (VCT) and effective refractory period (VERP) and nonsignificant decreases in dP/dtmax and blood pressure. The addition of halothane resulted in hypotension and in progressively increasing plasma bupivacaine levels secondary to reduced hepatic clearance, which led to further dose-related significant increases in VCT and VERP and to significant decreases in dP/dtmax and blood pressure. In other dogs given halothane but in which bupivacaine levels were held constant (1400 ng/mL), VCT remained constant and VERP lengthened slightly, whereas dP/dtmax decreased. We conclude that the combination of bupivacaine and halothane can cause adverse effects on ventricular contractility and intraventricular conduction.

Anesthesia↗