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PubMed1979

Advanced digoxin toxicity in renal failure: treatment with charcoal hemoperfusion.

Glycoside toxicity, a common and potentially fatal complication among patients taking digoxin, is treated basically by managing cardiac arrythmias until the patient can excrete enough drug to decrease the intoxication. Patients with renal failure, however, are particularly difficult to manage. We describe a case of advanced digoxin toxicity in an elderly man with severe renal failure, treated with a charcoal hemoperfusion device.

Aged↗
PubMed1999

Update on medications used to treat gastrointestinal disease in children.

Progress in the pharmacotherapy of pediatric gastrointestinal diseases continued during 1998 despite ongoing obstacles encountered by clinicians and researchers. The major change involved warnings that cisapride, a widely used prokinetic agent, could cause potentially fatal arrythmias in susceptible people. The risk for children is unclear and a consensus of prescribing guidelines is needed. Excellent pediatric-oriented reviews have been published that summarize our knowledge of proton pump inhibitors, probiotics, 5-hydroxtryptamine-3 (5-HT3) antagonists, and the treatment of gastrointestinal infections and chronic abdominal pain. Triple medication therapy for the eradication of Helicobacter pylori is now the standard of care, but the optimal combination and duration of therapy needs to be determined. Also described are interesting developments requiring further confirmation: the treatments of infectious diarrhea with zinc; achalasia and Hirschsprung's disease with botulinum toxin; weight loss with megestrol acetate; and sialorrhea with glycopyrollate.

Anti-Bacterial Agents↗
PubMed2003

Cardiopulmonary complications of intramedullary fixation of long bone metastases.

Intramedullary fixation of long bone metastases is an effective method of treating or preventing pathologic fractures. An important complication of this technique is the development of pulmonary embolism, which may occur at any number of steps during bone manipulation. Passage of normal marrow contents or tumor into the pulmonary circulation is thought to cause various biochemical, hemodynamic, or physical responses that lead to hypotension, arrythmia, and O2 desaturation. Death is a known risk of this procedure. Numerous surgical and anesthetic strategies have been developed to prevent or treat pulmonary embolic phenomena; however, the most important prophylaxis may be a heightened awareness of this possibility during any procedure that involves intramedullary manipulation of tumor containing bone.

Blood Coagulation Disorders↗
PubMed2002

The use of the SPSA method in ECG analysis.

The classification, monitoring, and compression of electrocardiogram (ECG) signals recorded of a single patient over a relatively long period of time is considered. The particular application we have in mind is high-resolution ECG analysis, such as late potential analysis, morphology changes in QRS during arrythmias, T-wave alternants, or the study of drug effects on ventricular activation. We propose to apply a modification of a classical method of cluster analysis or vector quantization. The novelty of our approach is that we use a new distortion measure to quantify the distance of two ECG cycles, and the class-distortion measure is defined using a min-max criterion. The new class-distortion-measure is much more sensitive to outliers than the usual distortion measures using average-distance. The price of this practical advantage is that computational complexity is significantly increased. The resulting nonsmooth optimization problem is solved by an adapted version of the simultaneous perturbation stochastic approximation (SPSA) method of. The main idea is to generate a smooth approximation by a randomization procedure. The viability of the method is demonstrated on both simulated and real data. An experimental comparison with the widely used correlation method is given on real data.

Algorithms↗
PubMed2005

Time-varying analysis methods and models for the respiratory and cardiac system coupling in graded exercise.

The analysis of heart period series is a difficult task especially under graded exercise conditions. From all the information present in these series, we are the most interested in the coupling between respiratory and cardiac systems, known as respiratory sinus arrythmia. In this paper, we show that precise patterns concerning the respiratory frequency can be extracted from the heart period series. An evolutive model is introduced in order to achieve tracking of the main respiratory-related frequencies and their time-varying amplitudes. Since respiration acts to modulate the sinus rhythm, we relate the frequencies and amplitudes to this modulation by analyzing in detail its nonlinear transformation giving the heart period signal. This analysis is performed assuming stationary conditions but also in the realistic case where the mean heart period, the amplitude, and the frequency of the respiration are time-varying. Since this paper is devoted to the theoretical and complete presentation of the method used in a physiological study published elsewhere, the capabilities of our method will be illustrated in a realistic simulated case.

Adult↗
PubMed2006

A single-lead ECG enhancement algorithm using a regularized data-driven filter.

We presented a novel way of deriving a subspace filter for enhancing a noisy electrocardiogram (ECG) signal contaminated by electromyogram (EMG). The new subspace filter was based on a multiple cycle prediction (MCP) modeling of a single-lead ECG. The adoption of an MCP model resulted in a data matrix more suitable for separating noise and signal subspaces than the linear prediction (LP) model that is implicitly assumed in many existing subspace filters. Alignment of ECG cycles of different length is required for MCP modeling and was handled by a dynamic time warping (DTW) algorithm. A run-time procedure was designed for automatically determining the signal space dimension adaptively. To validate the new filter in a quantitative way, 12 clean realistic ECG segments with different degrees of heart rate variability generated using the ECGSyn program were mixed with different realizations of EMG noise in the MIT-BIH Noise Stress Test Database and locally acquired EMG at a typical 10-dB signal-to-noise ratio. The performance of the proposed method was compared to three existing ECG enhancement algorithms and achieved encouraging results. In addition, various ECG recordings from MIT-Arrythmia database were also mixed with EMG noise and subjected to the same four filters resulting in a qualitative comparison of them.

Algorithms↗
PubMed1995

Mechanisms for reduction of cardiovascular risk by regular exercise.

1. Regular aerobic exercise causes cardiovascular, neural, humoral and metabolic changes. Many of these are likely to influence cardiovascular risk and the changes vary according to the level and duration of increased physical activity. 2. The case for exercise exerting beneficial effects derives from epidemiological data showing that sedentary subjects have, on average, double the risk of cardiovascular disease of active individuals. Post-infarct rehabilitation studies are also consistent with a beneficial effect of exercise. Large randomized controlled intervention studies have not been performed. 3. These benefits may be due to the effects of regular exercise on risk factors, direct effects on atheromatous vessels, or improvement in survivability in established coronary heart disease by reducing arrythmias or increasing tolerance of ischaemia. 4. There are direct effects of regular exercise on blood pressure (BP) and lipid profiles. These occur at different levels of physical activity. Other changes which would be expected to reduce cardiovascular risk include increased insulin sensitivity, reduced sympathetic activity and increased gain of the baroreceptor-heart rate reflex and increased arterial compliance. 5. In hypertensives these changes may improve outcomes, irrespective of the reduction in BP reported in some randomized controlled intervention studies.

Cardiovascular Diseases↗
PubMed1987

Myocardial preservation 1987: what is the state of the art?

The principles of myocardial preservation by hypothermic cardioplegia are: to induce cardiac arrest rapidly, to minimize energy requirements and prevent ischaemic damage during arrest, and to avoid reperfusion injury after arrest. These principles are put into practice by infusing an effective cold cardioplegic solution at the beginning of ischaemia and then every 20-30 min throughout ischaemia. Myocardial temperature should be maintained below 15 degrees C in all areas of the myocardium by topical cooling, efficient venous drainage and cardiac venting. The use of an oxygenated blood-based cardioplegic solution produces a modest improvement in myocardial recovery compared with a non-oxygenated crystalloid solution. During coronary reperfusion after arrest, ventricular distension should be avoided and coronary pressure should be sufficiently high to perfuse all areas of the myocardium, especially in patients with coronary stenoses. Developing areas in myocardial preservation include metabolic supplementation of the myocardium, the use of free radical scavengers, the prevention of atrial arrythmias and the use of coronary sinus cardioplegia. The increasing numbers of high risk patients presenting for surgery should stimulate the surgeon to adhere closely to the basic principles of myocardial preservation and to apply existing cardioplegic techniques meticulously. It should also challenge the investigator to increase basic understanding and improve methodology in this important area of cardiac surgery.

Cardioplegic Solutions↗
PubMed2005

QTc abnormalities in deliberate self-poisoning with moclobemide.

BACKGROUND: Several medications have been found to prolong the QT interval in overdose. This can predispose to torsade de pointes-type ventricular tachycardia. AIMS: To analyse the effects of moclobemide deliberate self-poisoning on the length of both QT and corrected QT (QTc) intervals. METHODS: Electrocardiograms (ECG) of all patients presenting to a regional toxicology service with moclobemide ingestion were reviewed. Cases where a cardiotoxic agent was coingested were excluded. QT and QTc parameters were compared with a comparison group of patients ingesting paracetamol or benzodiazepines. RESULTS: Of 75 patients where ECG were available, the median ingested dose was 4.5 g (interquartile range (IQR): 2.4-7.5; range: 0.6-18 g) and the median age was 34 years (IQR: 26-44). The mean QT interval was 415 ms (standard deviation (SD): 51 ms) with a mean QTc of 459 ms (SD: 44 ms), and were prolonged compared with the comparison group. Twelve female patients had a QTc > 500 ms and in seven of these causality was established based on a pre- or post-ECG with a QTc < 500 ms. Only 10% of the moclobemide cases had a heart rate (HR) > 100 beats per minute, making overcorrection of HR by Bazett's formula an unlikely cause of the findings. No cardiac arrythmias were observed other than one case of first-degree heart block. CONCLUSIONS: Moclobemide prolongs the QT and QTc intervals in overdose and a 12-lead ECG should be done on all moclobemide deliberate self-poisonings. Continuous cardiac monitoring for what is otherwise a relatively benign overdose would appear to be an inappropriate use of resources but can be considered in patients with a QTc > 500 ms or with known risks for QT prolongation.

Adult↗
PubMed1993

Effects of catecholamines on plasma potassium: the role of alpha- and beta-adrenoceptors.

The sympathetic nervous system plays an important role in the control of plasma potassium levels. Administration of adrenaline or noradrenaline evokes, in the majority of mammal species a dual response: first a short transient hyperkalaemia, followed by a maintained hypokalaemia. Alpha 1- and alpha 2-adrenoceptors mediate the initial hyperkalaemia through the activation of hepatic Ca(2+)-dependent-K(+)-channels. Stimulation of beta 1- and beta 2-adrenoceptors induces the late hypokalaemia by stimulation of skeletal muscle Na(+)-K(+)-ATPase. Beta 3-adrenoceptor stimulation may also have an effect on plasma potassium control since administration of selective beta 3-adrenoceptor agonists induces a decrease in plasma potassium. The simultaneous infusion of phenyleprine (alpha-adrenoceptor agonist) and isoprenaline (beta-adrenoceptor agonist) increases plasma potassium levels: this effect is several times larger than the algebric summation of the changes in plasma potassium when each agent is infused separately, thus suggesting potentiation. The physiological (changes in cell volume and function secondary to changes in ion fluxes) and clinical implications (pathophysiological conditions with hypo or hyperkalaemia, hyperkalaemic periodic paralysis, ventricular arrythmias) of these findings are discussed.

Animals↗
PubMed1982

Antiarrhythmic effects of Org 6001 in rats: correlation with plasma and tissue drug concentrations.

The antiarrhythmic effects of Org 6001 following oral administration in the rat have been assessed and correlated with plasma, myocardial and skeletal muscle drug concentrations. Arrythmias were induced by coronary artery ligation in anaesthetized rats. Org 6001 (10, 20, 50 and 100 mg/kg given 1 h before ligation) significantly reduced mortality and the incidence of ventricular fibrillation in the 0-30 min post ligation period. Only the highest dose of drug also significantly reduced the number of ventricular ectopic beats following ligation. A linear relationship was observed between the oral dose and the Org 6001 concentrations in plasma and skeletal muscle determined 90 min after drug administration. The Org 6001 concentration in the myocardium was not linearly related to the administered dose and Org 6001 appeared to be concentrated to a higher extent in cardiac than in skeletal muscle at that time. No statistically significant difference in drug levels in the ischaemic left ventricle and normal right ventricle plus septum was observed. The antiarrythmic effect of Org 6001, as measured by changes in the incidence of ventricular fibrillation, correlated with myocardial concentrations of the drug.

Androstanols↗
PubMed1987

Electrophysiological effects of diclofurime on rabbit and frog atrial heart muscle.

The effects of diclofurime on the electrical activity of the rabbit sinus node, rabbit atria and frog atrial fibres were studied using microelectrode and the double sucrose gap voltage-clamp techniques respectively. In rabbit sinus node, diclofurime (10(-7) M to 10(-6) M) decreased the action potential (AP) amplitude and maximum rate of depolarization (Vmax), increased the AP duration and slowed the sinus rate. In rabbit atria, the drug reduced the amplitude of the depolarizing phase and Vmax, lengthened the AP duration and decreased the resting membrane potential. In frog atrial fibres, the drug (10(-5) M) depolarized the resting membrane potential, decreased Vmax as well as the plateau amplitude. It inhibited the sodium current (INa) with a dissociation constant of 3.7 X 10(-6) M and a one to one relationship between the drug molecule and the Na channel. Diclofurime did not alter the apparent reversal potential for the fast Na current (ENa) but it inhibited the sodium conductance (GNa) in a frequency-dependent manner. Diclofurime also blocked the slow inward current (Islow) without alteration of Eslow. The block of Islow occurred with a dissociation constant of 2 X 10(-5) M and unity stoichiometry. The data suggest that diclofurime might be effective in the control of cardiac arrythmias since it exhibited both local anaesthetic-like and calcium antagonistic properties.

Action Potentials↗
PubMed1989

Effect of D,L-carnitine on the response of the isolated heart of the rat to ischaemia and reperfusion: relation to mitochondrial function.

1. The effect of 100 microM (20 micrograms ml-1) of D,L-carnitine was studied on the isolated heart of the rat subjected to 30 min of low flow ischaemia followed by reperfusion. 2. In untreated hearts (n = 30) ischaemia produced an almost total loss of contractility (P less than 0.05 compared with non-ischaemic time control) which was accompanied by an increase in resting tension of approximately 235% (P less than 0.05). Ventricular arrhythmias developed during ischaemia in 100% (P less than 0.05) of untreated hearts studied. Following reperfusion, untreated hearts recovered 16.3% of contractile function and demonstrated a 60% elevation in resting tension. The incidence of reperfusion-associated ventricular fibrillation was 60%. 3. Carnitine treatment produced no effect on either the contractile depression or the elevation in resting tension during ischaemia but did significantly decrease the incidence of arrythmias at the termination of ischaemia to 63.3% (n = 30, P less than 0.05). In the presence of carnitine, contractile recovery at the end of reperfusion was significantly increased to 30.2% (n = 10, P less than 0.05) and the elevation in resting tension was decreased to 30% (n = 10, P greater than 0.05). The incidence of ventricular arrhythmias during reperfusion was significantly reduced by carnitine. 4. Two populations of mitochondria, subsarcolemmal (SLM) and interfibrillar (IFM) isolated at the end of the ischaemic period exhibited an overall increase in oxidative phosphorylation rates as well as uncoupled oxygen consumption; both phenomena were more pronounced with IFM. Carnitine generally potentiated this response. A 29% and 38% inhibition in atractyloside-sensitive ADP uptake was observed in SLM and IFM, respectively, following ischaemia, which was partially prevented by carnitine. 5. After 10min of reperfusion, adenosine diphosphate (ADP) uptake in SLM was further reduced to 55% of control whereas with IFM, uptake was not different from that seen at the end of ischaemia. Mitochondria isolated from hearts after 30 min of reperfusion revealed a significantly depressed oxidative phosphorylation as well as ADP/ATP translocase activity. These defects were partially reversed in hearts perfused with carnitine. 6. Our study demonstrates that D,L-carnitine protects the rat isolated heart against injury associated with ischaemia and reperfusion through a mechanism associated with improved mitochondrial function.

Animals↗
PubMedDate not supplied

Surgical palliation of severe tricuspid valve stenosis in a dog by use of Fontan's procedure.

OBJECTIVE: To describe surgical treatment of tricuspid valve stenosis using the Fontan procedure in a young dog. STUDY DESIGN: Case report. SAMPLE POPULATION: One client-owned dog RESULTS: A six month old female Labrador retriever was diagnosed with tricuspid obstruction. The dog had a displaced tricuspid valve and small right ventricle and had progressed to right-sided (backward) cardiac failure. A Fontan procedure (connection of the right atrium to the pulmonary artery with a prosthetic conduit) was performed. Within three days the right atrial pressure had dropped from a preoperative value of 33 mm Hg to 8 mm Hg and the ascites was significantly reduced. The dog died suddenly two months after surgery. Postmortem examination of the heart showed a greatly enlarged right atrium and hypoplastic right ventricle. The tricuspid valve leaflets were fused and displaced ventrally leaving an opening measuring 3x5 mm between the chambers. The conduit was intact with no evidence of leakage or thrombosis. CONCLUSIONS: Palliation of tricuspid stenosis using the Fontan procedure can be performed in dogs. Sudden death may occur and is most likely because of cardiac arrythmias.

Animals↗
PubMed2005

Cardiac presentation of ALK positive anaplastic large cell lymphoma.

Cardiac involvement as an initial presentation of malignant lymphoma is a rare occurrence. We report the case of an immunocompetent 29-year-old male who presented with syncope and arrythmias secondary to a ventricular cardiac mass. Transcutaneous cardiac biopsy was non-diagnostic, therefore an open cardiac biopsy was performed from which a provisional diagnosis of a cardiac inflammatory pseudotumour was made. Six months after presentation, he developed several subcutaneous lesions with systemic symptoms. Histological and immunophenotypic review of the initial cardiac biopsy revealed features consistent with a diagnosis of CD30, ALK1 positive anaplastic large cell lymphoma (ALCL). Despite intensive treatment with combination chemotherapy, there was significant progression of disease, and he died 11 months after diagnosis. The overall prognosis of cardiac lymphoma remains poor, which may be due to the often late presentation of the tumour. To our knowledge, this is the first reported case of a cardiac ALK positive ALCL. Although rare, cardiac presentation of ALCL should be added to the list of differential diagnoses of cardiac lymphomas.

Activin Receptors, Type I↗
PubMed1999

Correlation between high intake of glycyrrhizin and myolysis of the papillary muscles: an experimental in vivo study.

The ingestion of large quantities of glycyrrhizin, whether as a drug or a sweetener, is known, in susceptible subjects, to induce a syndrome similar to hypermineralcorticoidism, with bouts of hypertension, hypokaliaemia and rabdomyolysis, sometimes associated with severe renal failure and hypokaliaemia-induced arrythmias. Glycyrrhizin is also known to isomerize into the glycyrrhetic (or glycyrrhetinic) acids 18alpha- and 18beta-. In previous works, we reported that these metabolites cause bouts of hypertension and reduction in diuresis at low doses in the rat. In particular, the alpha isomer causes significant elimination of the calcium ion in the urine. The present findings confirm that 18alpha-glycyrrhetic acid is more toxic than either glycyrrhizin or the beta isomer. Histopathological study of tissue samples taken from rats treated with the alpha isomer also reveal selective damage to the myocardium with oedema, myolysis, apoptosis and blistering of the sarcoplasm. These effects begin to appear in the course of subchronic treatment, they manifest themselves in acute treatment and correlate closely with the electrocardiographic changes recorded in rats acutely treated with 18alpha-glycyrrhetic acid.

Animals↗
PubMed2003

Carnitine-acylcarnitine translocase deficiency: case report and review of the literature.

AIM: Carnitine-acylcarnitine translocase (CACT) deficiency is an inborn error of metabolism involving the mitochondrial beta-oxidation of long-chain fatty acids. The aim of this study was to report on a new case (neonatal phenotype) and review the literature data on 24 previously reported cases. METHODS: Clinical data of the new case are described and compared with the previous reports. RESULTS: The patient with a novel mutation had clinical features and biochemical findings similar to those of the other reported patients. CONCLUSION: CACT is an entity in which clinical encephalopathy, hepatomegaly and arrythmias are common. Hyperammonaemia and elevation of creatine kinase seem to be constant findings as in other disorders of mitochondrial beta-oxidation of long-chain fatty acids. The mortality rate is very high.

Carnitine Acyltransferases↗
PubMed1996

Aprotinin effects related to oxidative stress in cardiosurgery with mechanical cardiorespiratory support (CMCS).

There is evidence to support a relationship between oxidative stress and protease release in "ischemia-reperfusion damage." We have proposed that aprotinin may exert an antioxidant effect. A double blind clinical trial was performed with a control (G-1) and treated (G-2) groups, both submitted to CMCS. Blood samples were taken 5 times. Biochemical indicators were measured spectrophotometrically. Aprotinin was supplied by Bayer. Malonildialdehyde levels were greater in G-1 (7.2 +/- 3.6 nmoles/ml) than in G-2 (4 +/- 1.65) at the time of reperfusion. Phospholipase A2 exhibited a tendency of higher activity in G-1 than in G-2. Uric acid levels were higher in G-2 (431 +/- 274 mumoles/1) than in G-1 (224 +/- 188) at 5 minutes after aortic clamping, and catalase activity was greater in G-2 (294 +/- 55 KU/1) than in G-1 (118 +/- 47) at time of reperfusion. Low cardiac output was 10% in G-2 and 30% in G-1. Arrythmias appeared in 30% of G-2 and in 60% of G-1. These results suggest an antioxidant effect of aprotinin under ischemia-reperfusion conditions.

Aprotinin↗