Signal distortion in the electrocardiogram due to inadequate phase response.
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Electrocardiography↗
Biomedical subjects
R Vincent
Publications and source records attributed to R Vincent.
Staging and prognostic factors in small cell carcinoma of the lung.
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Biopsy, Needle↗
[Silo accidents (apropos of the catastrophic accident in Metz)].
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Accidents, Occupational↗
The nuclear stethoscope in the cardiac care unit.
The portable single-crystal scintillation probe (nuclear stethoscope) provides beat-to-beat comparisons of stroke volume and gated measurements of ejection fraction. Comparisons of ejection fractions obtained with the stethoscope and a gamma camera show acceptable correlation except for readings in the very high and very low ranges. The use of the device has been demonstrated by showing changes in ejection fraction obtained with glyceryl trinitrate.
Coronary Disease↗
Use of an automated external defibrillator-pacemaker by ambulance staff.
A new portable external device detects ventricular fibrillation and profound bradycardia or asystole by analysis of wave forms; it automatically delivers a defibrillating shock or repetitive pacing stimuli. Ambulance crews used the device on 27 cardiac-arrest patients. The initial group (16) was restricted to patients prejudged as probably beyond successful resuscitation, and none survived. The subsequent group (11) was not restricted. 5 were discharged alive from the hospital. The device is simple to use, and its application by modestly trained technicians and lay people may be feasible. Widespread use of the device as an adjunct to conventional cardiopulmonary resuscitation could reduce mortality from out-of-hospital cardiac arrest. The capability for external cardiac pacing enhances the efficacy of treatment.
Ambulances↗
Defibrillation at a football stadium: an experiment with Brighton and Hove Albion.
Over a five-year period arrangements have been made to increase the prospects of resuscitation for victims of sudden death at a large football stadium. Seven cases of ventricular fibrillation occurred. Four were resuscitated successfully and were subsequently discharged from hospital.
Aged↗
Comparison of haemodynamic responses to dobutamine and salbutamol in cardiogenic shock after acute myocardial infarction.
Nine patients with critically reduced cardiac output after acute myocardial infarction underwent a single cross-over comparison of dobutamine and salbutamol to compare the haemodynamic effects of these drugs, which have, respectively, predominantly beta 1-adrenergic and beta 2-adrenergic agonist activity. The responses were used to select the more appropriate treatment for individual patients. Only relatively small responses were obtained: those with poorest baseline measurements tended to show the least effect. When the results from the series were averaged, dobutamine (250-750 microgram/min) caused a small but progressive increase in cardiac index (1.8 to 2.2 1/min/m2) throughout the dose range. Systemic blood pressure was not increased, and calculated systemic vascular resistance fell from 25 to 19 units. Heart rate rose from 107 to 118 beats/min and stroke index from 17 to 19 ml/beat/m2. Pulmonary artery end-diastolic pressure fell from 18 to 15 mm Hg. Salbutamol (10-40 microgram/min) produced a similar progressive increase in cardiac index, from 1.6 to 2.21/min/m2. Systemic blood pressure was not altered, and systemic vascular resistance fell from 25 to 20 units. Heart rate rose from 105 to 119 beats/min and stroke index from 16 to 19 ml/beat/m2. Pulmonary artery end-diastolic pressure did not fall. Dobutamine and salbutamol have closely similar haemodynamic effects when used in cardiogenic shock after acute myocardial infarction. Both drugs increase cardiac index but heart rate also rises, and the increase in stroke index is relatively small. Mean arterial pressure is altered little by either agent, but dobutamine (in contrast with dopamine) tends to reduce pulmonary artery end-diastolic pressure, which may be beneficial.
Aged↗
Role of labetalol in acute myocardial infarction.
1 The role of labetalol in managing acute myocardial infarction is reviewed. 2 After intravenous infusion labetalol lowers blood pressure in patients with increased blood pressure associated with acute myocardial infarction. 3 Although average heart rate was decreased, cardiac index fell only slightly and stroke index was substantially unchanged. 4 In patients whose pretreatment pulmonary artery end-diastolic pressures were increased, labetalol induced decreases, whereas in the presence of normal pressures, these were unchanged. 5 It is concluded that labetalol infusion in patients with acute myocardial infarction is unlikely to precipitate heart failure and is likely to be of value in reducing myocardial oxygen requirement.
Acute Disease↗
The effects of amiodarone on thyroid function.
The effects of amiodarone on thyroid function tests in 100 patients treated for 6 weeks to 8 years are reported. One patient became thyrotoxic and 10 developed latent or overt hypothyroidism. Twenty-five patients remained clinically euthyroid throughout, but had free thyroxine indices above the normal range. In these patients with apparently anomalous results, total tri-iodothyronine was normal in 19 cases and low in 1; conversely, free thyroxine was high in all 17 cases in which it was measured. Thyrotrophin releasing hormone (TRH) tests were abnormal in 4 of the 13 patients who had the test. Reverse tri-iodothyronine was significantly raised after 2 weeks amiodarone in 5 healthy subjects, but an equivalent amount of iodine in 9 healthy individuals did not significantly affect any of these tests. We believe that these changes are due in part to inhibition of peripheral conversion of thyroxine to tri-iodothyronine with diversion to reversed tri-iodothyronine. Thyroid function tests should be checked once or twice a year in all patients on maintenance amiodarone. Tests indicating hypothyroidism are likely to be clinically relevant, whereas levels of thyroxine suggesting thyrotoxicosis may be misleading and do not usually imply the need to discontinue treatment with the drug.
Adult↗
The action on cellulose and its derivatives of a purified 1,4-beta-glucanase from Trichoderma koningii.
The specific properties have been examined of the 1,4-beta-glucanase component of Trichoderma koningii that participates in an early and effective stage of random breakdown of native cellulose to short fibres. The enzyme was purified and freed from associated components of the cellulase complex (particularly beta-glucosidase) that interfere with, and complicate interpretation of, the action of such enzymes. Purification increased the specific activity 25-fold over culture filtrates; the enzyme hydrolysed CM-cellulose faster than the purified beta-glucosidase from the same organism hydrolysed any of its substrates (cellobiose or cellodextrins). The specificity of the glucanase was directed towards soluble derivatives of cellulose, CM-cellulose and cellodextrins, and not to insoluble cellulose or alpha-linked polymers. The approximate Km was 2.5 mg of CM-cellulose . ml-1 at 37 degrees C at the optimum pH, 5.5, where enzymic activity was maximal with 6--7 mg of CM-cellulose . ml-1 and inhibited by higher concentrations. The temperature optimum was 60 degrees C. The glucanase attacked larger cellodextrins (cellohexaose to cellotetraose, in that order) much more readily than smaller dextrins (cellobiose and cellotriose) and released a mixture of products, glucose up to cellopentaose, which was quantitatively determined after chromatography on charcoal. Similar examination of hydrolysates of the reduced cellodextrins showed clearly the high specificity of the enzyme for the central bond of its natural substrates (the cellodextrins), whatever their chain length, and indicated the nature of the enzyme as an endoglucanase. Outer bonds shared a weaker, but similar, susceptibility to enzymic cleavage. Transferase activity was absent and no larger dextrins than the initial substrate were formed.
Carboxymethylcellulose Sodium↗
Pulmonary oedema without critical increase in left atrial pressure in acute myocardial infarction.
Twelve patients with acute myocardial infarction and radiological evidence of pulmonary oedema were observed in whom the left atrial pressure, measured indirectly as pulmonary artery end-diastolic pressure, was not critically increased (range 5-12 mm Hg with reference to sternal angle). Eight of the patients had been treated with frusemide, but only six had responded: hence in at least half of the series diuresis could not account for the anomalous finding. Six patients with low cardiac output were given infusions to expand plasma volume. Appreciable increments in mean values for cardiac index (1.6 to 2.0 1/min/m2), stroke index (18 to 23 ml/beat/m2), mean arterial pressure (65 to 86 mm Hg), and pulmonary artery end-diastolic pressure (8 to 15 mm Hg) were recorded. This group, and the remaining six patients with higher cardiac output, survived to leave hospital. Delay in radiographic clearing after a fall of left atrial pressure was a possible explanation for the relatively low pulmonary artery end-diastolic pressures, especially in the patients treated successfully with diuretics. Other mechanisms, such as alterations in pulmonary vascular permeability, might also have contributed to the syndrome. Pulmonary oedema without a critical increase in the left atrial pressure is unusual in acute myocardial infarction but the therapeutic implications are important. Withdrawal;of diuretics may be indicated, and in some cases expansion of plasma volume may lead to striking clinical improvement.
Aged↗
Phase II study--intra-arterial BCNU therapy for metastatic brain tumors.
Thirty-one patients with metastatic brain tumors (MBT) from lung cancer and ten patients with MBT from melanoma received BCNU, 100 mg/m2, every four weeks by intracarotid and/or vertebral artery infusion into each involved site. Twenty-five patients with lung cancer and all melanoma patients are currently evaluable. Twelve patients with lung cancer had complete and partial responses lasting from 1 to 14 months. Four of them with the histologic diagnosis of small cell carcinoma, one with large cell carcinoma and one with squamous cell carcinoma showed complete response. None of the patients with melanoma MBT experienced any response. All of the patients had periorbital erythralgia and/or occipital pain during the infusion. Four patients manifested mild focal seizures during the infusion or 6 to 24 hours after the treatment. Transient confusion with disorientation was observed in two patients 4 and 24 hours, respectively, after a BCNU infusion. Two patients developed reversible thrombocytopenia after the fifth course of the IA chemotherapy. Median survival of patients with MBT from lung carcinoma was 4 months, with two of them still alive at 10 and 14 months, respectively. Only one patients of the 25 with lung carcinoma died from MBT. Failure to control the primary disease resulted in the deaths of a vast majority of the patients.
Adenocarcinoma↗
[Significance of sulfamethoxazole-trimethoprim in dentistry].
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Adult↗
Lysosome enlargement in the Chediak-Higashi syndrome.
The Chediak-Higashi syndrome (CHS) is characterized by the occurrence of large inclusions in granulocytes and other cells. Analogs of the human disease are known in several species. Severity of clinical manifestations and extent of neutrophil alteration correlate closely and decrease in the order: man, mink, and mouse. The megabodies in granulocytes of Aleutian mink with CHS represent abnormal primary lysosomes that develop through fusion between stored lysosomal granules. The CHS alteration in mink affects azurophil granules of neutrophils more severely than the granules of eosinophils or basophils and spares specific granules of neutrophils. Several other types of cells exhibit megabodies that apparently cause little or no dysfunction in beige mice showing the CHS defect. Mast cells in these mice contain enlarged storage lysosomes, and Type II pneumocytes and gastric chief cells show enlarged secretory granules. Gastric chief cells, parietal cells, and hepatocytes enclose hypertrophied secondary lysosomes that function in autophagy whereas proximal renal tubules and cultured fibroblasts display hypertrophic secondary lysosomes of heterophagic nature. The cell distribution of megabodies in beige mice suggests they result from increased fusion between organelles delimited by membranes adapted to sequestration of hydrolytic enzymes.
Animals↗
A flexible signal-averaging system for cardiac waveforms.
The repetitive nature of cardiac waveforms renders them suitable for processing by signal averaging. A flexible system is described, based on a general-purpose digital computer, capable of averaging a variety of cardiac signals in excess of 0.5 microV containing frequency components below a theoretical Nyquist limit of 5 kHz. Important features of the system include real-time processing capability at a high level of interactive control, and the facility to trigger the averaging process accurately from any part of either the data or a synchronous reference waveform. Application of the system to electrocardiographic and phonocardiographic signals at conventional gain has enabled clinically useful records to be obtained in the face of obtrusive environmental noise. The averaging of signals of a similar nature after considerably increased amplification has revealed cardiac activity unseen in conventional records in a total of 81 subjects.
Analog-Digital Conversion↗
Thyrotoxic myopathy presenting as dysphagia.
A case of aspiration pneumonia due to incoordination of swallowing is described. Its aetiology lies in the myopathy of thyrotoxicosis and a tentative hypothesis as to its causation is suggested.
Deglutition Disorders↗
Low voltage electrical activity preceding right atrial depolarisation in man.
Electrical recordings were made in the high right atrium in 28 patients undergoing cardiac catheterisation and in 3 healthy volunteers. After filtering and amplification by 3 to 10 million times, the signals were passed through a signal averaging process in a digital computer. Of the 28 subjects who had technically satisfactory recordings, 23 showed low voltage electrical activity preceding the conventionally-recorded atrial depolarisation. The low voltage activity started 50 to 200 ms before the atrial deflection and was variable in shape. These early signals may be the result of activity in the region of the sinus node.
Arrhythmia, Sinus↗
Epileptiform seizures with maprotiline hydrochloride.
Two cases are described who developed epileptic seizures whilst taking maprotiline hydrochloride in therapeutic dosage. In both cases the electroencephalogram was normal and the fits stopped on withdrawal of the drug.
Adult↗