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Biomedical subjects

D Kilpatrick

Publications and source records attributed to D Kilpatrick.

At least 73 records · Page 4Linked to original sources
PubMed1980

Trichostrongylus vitrinus: the influence of age of sheep and population size on the intestinal distribution.

Two age groups of parasite-free lambs, 4 months and 8 months, were infected with 50 000 infective larvae (L3) of T. vitrinus. A further group of 8 month old lambs were infected with 250 000 L3 T. vitrinus. The lambs were slaughtered at intervals after infection, and the size and linear distribution of their intestinal worm burdens examined and compared statistically. After the 50 000 L3 infections, it was found that a higher percentage of the initial inoculum had become established in the younger lambs but that there were no differences between the intestinal distributions of the population in either age group. After infection with 250 000 L3, the percentage of the larvae retained changed with time. Up to sixteen days post infection, 38% of the larvae administered were retained; thereafter the percentage fell to 22%. The linear distribution of the population in this size of infection showed that a significantly greater percentage was present between 4.8 and 7.2 metres distal to the pylorus when compared with that after infection with 50 000 L3.

Age Factors↗
PubMed1980

Vectorcardiographic analysis of ventricular tachycardia.

From a study of 69 patients with ventricular tachycardia using digitised vectorcardiograms, it is suggested that the following features are evidence of a ventricular origin. 1. Anterior QRS predominantly in the left anterior quadrant. 2. Slow initial tangential QRS velocity greater than or equal to 20 ms in the presence of an anterior QRS monophasic loop. 3. QRS totally in the right posterior quadrant. 4. In the presence of a QRS in the left posterior quadrant slow anterior QRS initial forces lasting greater than or equal 20 ms in the horizontal plane. The following features are suggestive of a ventricular origin. 1. Slow initial tangential QRS velocity greater than or equal to 20 ms in the presence of an anterior QRS loop resembling right bundle branch block (RBBB). 2. Anterior monophasic QRS loop with counterclockwise rotation. 3. Slow initial QRS forces posteriorly (TV of first 40 ms less than 10 mV . s-1) in the presence of a QRS loop in the left posterior quadrant. 4. A vertical right QRS axis greater than or equal to +60 degrees in the presence of a left bundle branch block (LBBB) loop in the horizontal plane and any axis greater than or equal to +90 degrees less than or equal to -160 degrees. The importance of three simultaneous perpendicular leads for recording or arrhythmias is stressed. In addition vectorcardiograms have clearly separated multifocal ventricular tachycardia from multiformity, fusion beats with and without aberration, and bundle branch ventricular tachycardia. It is suggested that further study of the QRS waveform at the initiation and termination of ventricular tachycardia will elucidate the mechanisms and types of tachycardias.

Diagnosis, Differential↗
PubMed1980

Assessment of long-term plasma exchange for familial hypercholesterolaemia.

The effectiveness of repeated plasma exchange with 2 to 4 litres of plasma protein fraction as long-term treatment for familial hypercholesterolaemia has been evaluated in six severely affected patients receiving conventional cholesterol lowering treatment. Cell-separator mediated exchange at monthly intervals for one to two years reduced mean serum cholesterol levels from 18.5 mmol/l (715 mg/dl) to 12.4 mmol/l (480 mg/dl) in two female homozygotes but failed to influence xanthomata or prevent a two- to threefold increase in their left ventricular aortic systolic pressure gradients. More effective reduction of mean serum cholesterol levels from 15.7 mmol/l (608 mg/dl) to 8.6 mmol/l (333 mg/dl) in two male homozygotes by plasma exchange at fortnightly intervals for two to three years was accompanied by resolution of xanthomata and by stabilisation of aortocoronary lesions. In two male heterozygotes with angina, coronary angiographic appearances were unaltered or improved after one to two years of thrice-monthly plasma exchange, which reduced mean serum cholesterol levels from 6.4 mmol/l (248 mg/dl) to 4.7 mmol/l (182 mg/dl). We conclude that plasma exchange every one to two weeks, combined with oral nicotinic acid and/or cholestyramine, retards the rate of progression of atheroma in homozygotes and possibly induces regression in heterozygotes.

Adult↗
PubMed1980

QRS waveform of ventricular extrasystoles and their differentiation from aberrant conduction.

Horizontal and frontal plane QRS loops of patients in sinus rhythm with uniform ventricular extrasystoles were constructed from digitised Frank orthogonal electrocardiogram. In 4 patients ventricular extrasystoles were indistinguishable from right bundle-branch complexes, and in another 4 from left bundle-branch complexes. In 25 patients ventricular extrasystoles showed an initial delay (greater than or equal to 20 msec) of the QRS, followed by an R loop, which in 13 patients resembled LBBB complexes, and 12 patients resembled RBBB complexes with an anterior clockwise loop in the horizontal plane. However, the frontal plane loop was often atypical of either RBBB or LBBB. In 51 patients ventricular extraplane loop was often atypical of either RBBB or LBBB. In 51 patients ventricular extrasystoles and an initial delay which was prolonged into the efferent limb of the QRS loop with acceleration of the afferent limb and/or the QRS loop was directed anteriorly, inferiorly and to the left. Conventional recordings of these extrasystoles usually showed an initial slow upstroke (or downstroke) of the QRS resembling a delta wave. It is suggested that extrasystoles resembling bundle-branch complexes arise close to the main bundle branches but that the other extrasystoles arise at the Purkinje-myocardial junction. Identification and differentiation of ventricular extrasystoles from aberrant conduction is aided by vectorcardiography.

Bundle-Branch Block↗
PubMed1979

Reduction of blood viscosity following plasma exchange.

The effect of plasma exchange with plasma protein fraction on blood viscosity was determined in seven hyperlipoproteinaemic patients with coronary or peripheral vascular disease. This resulted in decreases in whole blood viscosity of 83% and 30% respectively at the lowest and highest shear rates studied, and decreases of 21% and 59% in plasma viscosity and fibrinogen. Serum cholesterol and triglyceride were reduced by 66% and 48% respectively. Sequential studies in two patients showed that blood viscosity returned to near-basal values by the 6th day. These findings suggest that plasma exchange may result in short-term enhancement of blood flow in vessels where low shear rates predominate.

Adolescent↗
PubMed1978

Ventricular tachycardia due to cardiac ischaemia: assessment by exercise electrocardiography.

Although ventricular tachycardia is a well-known complication of myocardial ischaemia and may be provoked by exercise, many patients may appreciate only the angina and be unaware of the unduly rapid heart rate that precipitates it. Exercise testing is needed to show this arrhythmia and to enable treatment to be started.Twenty-three patients were found to have chronic ischaemic heart disease complicated by ventricular tachycardia. Six patients with old myocardial infarction had ventricular tachycardia at rest which required conversion to sinus rhythm; 17 patients developed ventricular tachycardia only when they exercised. In 12 of these 17 patients coronary angiography showed disease of the anterior descending branch of the left coronary artery; other vessels were usually also affected. Although beta-adrenergic blocking drugs increased exercise tolerance, ventricular tachycardia still occurred when the heart rate on exercise reached a level similar to that before treatment. In five patients coronary artery bypass surgery was performed because of angina and exercise-induced ventricular tachycardia. Exercise tolerance was increased in all three patients who underwent exercise tests after operation, and in two of these patients, both of whom were known to have patent grafts, ventricular tachycardia was abolished.If part of the beneficial effect of coronary bypass surgery is preventing life-threatening ventricular arrhythmias it is essential to detect these, and ambulatory monitoring and stress testing have a complementary role.

Adult↗
PubMed1978

Vectorcardiographic features of ventricular extrasystoles correlated with conventional scalar electrocardiographic interpretation.

Horizontal and frontal plane QRS loops of patients in sinus rhythm with uniform ventricular extrasystoles were constructed from digitised Frank orthogonal electrocardiograms. In 4 patients ventricular extrasystoles were indistinguishable from right bundle-branch complexes, and in another they were indistinguishable from left bundle-branch complexes. In 25 patients ventricular extrasystoles showed an initial delay (greater than or equal to 20 ms) of the QRS, followed by an R loop, which in 13 patients resembled left bundle-branch block complexes, and in 12 patients resembled right bundle-branch block complexes, with an anterior clockwise loop in the horizontal plane. However, the frontal plane loop often did not resemble that of either right or left bundle-branch block. In 51 patients ventricular extrasystoles had an initial delay which was prolonged into the efferent limb of the QRS loop with acceleration of the afferent limb, and/or the QRS loop was directed anteriorly, inferiorly, and to the left. Conventional recordings of these extrasystoles usually showed an initial slow upstroke (or downstroke) of the QRS resembling a delta wave. Apparently uniform ventricular extrasystoles on scalar recordings were shown to be multiform vectorcardiographically though in all such cases the direction of the initial 40 ms forces was constant. It is suggested that the slow initial inscription of ventricular extrasystoles is the result of excitation of ventricular muscle directly and not through specialised His-Purkinje fibres, and that the direction of such initial forces may indicate the ventricular origin of ventricular extrasystoles.

Bundle-Branch Block↗
PubMed1978

Synthesis of chromogranins and dopamine beta-hydroxylase by perfused bovine adrenal glands.

The incorporation of [3H]leucine into chromogranins and into soluble and membrane-bound dopamine beta-hydroxylase (DBH) was studied in isolated perfused adrenal glands. [3H]chromogranins and [3H]DBH were quantitatively determined by immunoprecipitation. The amounts of soluble [3H]DBH formed were about equal to the amounts of membrane-bound [3H]DBH whereas the amounts of [3H]chromogranin were 5- to 20-fold greater than that of soluble [3H]DBH. On continuous sucrose density gradients, [3H]chromogranin was unimodally distributed after 2- to 20-h chase periods and accumulated in a vesicle having a lower buoyant density than mature chromaffin vesicles. At 2 h both membrane and soluble [3H]DBH were both bimodally distributed whereas after a 20-h chase period the distribution of soluble and membrane [3H]DBH was essentially unimodal and paralleled the distribution of [3H]chromogranin. These studies indicate that [3H]chromogranin, soluble [3H]DBH, and membrane [3H]DBH are synthesized concomitantly, but that each is transported into chromaffin vesicles at different rates.

Adrenal Glands↗
PubMed1978

Clinicians, the Mount Sinai program and the Veterans' Administration program evaluated against clinico-pathological data derived independently of the electrocardiogram.

221 electrocardiograms (ECGs) recorded from adult subjects with cardiac symptomatology were interpreted by clinicians and the Mount Sinai (MS) and Veterans' Administration (VA) computer programs. After the clinicians had eliminated their interobserver variability, their interpretations and those of the computer programs were compared with the corresponding clinico-pathological data that had been derived independently of the ECG. A measure of overall diagnostic accuracy was used which showed that the performance of the 2 computer programs was similar and somewhat worse than that of the clinicians. The clinicians and the computer programs were not as good at diagnosing the ECGs of women as at diagnosing those of men. As the VA program's interpretations may be altered by including information about the patient's provisional diagnosis, 6 different sets of these prior probabilities were used to analyse 141 of the original 221 ECGs. Different fixed sets of prior probabilities made only a small difference to overall diagnostic accuracy but a marked difference to the VA program's ability to differentiate Normal from Abnormal. Optimizing the prior probabilities for the individual subjects increased the VA program's overall diagnostic accuracy up to that of the clinicians. Both computer programs correctly diagnosed sinus rhythm as the dominant rhythm in 165 out of 177 subjects. The MS program diagnosed the dominant rhythm as Atrial Fibrillation in 35 out of 41 subjects and the VA program in 27 (X(2) = 3.24; not significant). ECG interpretation; Mount Sinai program; Veterans' Administration program; independent clinico-pathological data; sex differences in the ECG; prior probabilities.

Adult↗
PubMed1977

QRS voltage of the electrocardiogram and Frank vectorcardiogram in relation to ventricular volume.

Left ventricular volumes were estimated in 59 patients, who were investigated by single plane ventriculography and coronary arteriography. The relation of the left ventricular end-diastolic volumes to the QRS voltage of the 12-lead electrocardiograms and Frank vectorcardiograms was examined. It was found that the maximum spatial QRS voltage and the R wave voltage of leads V5 and V6 in patients without left ventricular hypertrophy were inversely correlated with end-diastolic volume. This inverse relation of QRS voltage and left ventricular volume may explain loss of QRS voltage with dilatation of the heart. In patients with left ventricular hypertropy QRS voltage is usually positively correlated with the degree of hypertrophy, but there is no significant correlation in the presence of cardiac dilatation. If the results of this study are extrapolated to patients with left ventricular hypertrophy and cardiac dilatation, then the inverse correlation of volume and QRS voltage may reduce the diagnostic sensitivity of unipolar chest lead and vectorcardiographic criteria of left ventricular hypertrophy.

Cardiac Volume↗
PubMed1976

Exercise vectorcardiography in diagnosis of ischaemic heart-disease.

The changes in the cardiac electric field during exercise have been studied by conventional vectorcardiographic techniques. Criteria have been developed to distinguish the changes seen in patients with coronary-artery disease proven angiographically from the changes in patients with normal coronary arteriograms. These criteria were derived from a learning set of 105 patients. Vectorcardiograms were taken immediately before and immediately after a maximal treadmill exercise test. In this group of 105 patients--72 with abnormal coronary arteries and 33 with normal coronary arteries--vectorcardiography before and after exercise diagnosed correctly 86% of the abnormals and 82% of the normals. This gives a sensitivity of 86% and a specificity 82%. ST-segment analysis in the same group gave a sensitivity of 60% and a specificity of 85%. The same criteria applied blind to a second testing set of 92 patients gave a sensitivity of 84% and a specificity of 65%. In the same group ST-T analysis gave a sensitivity of 56% and a specificity of 78%. The sensitivity with these criteria compares favourably with the best results so far achieved with ST-segment analysis aided by computer. This technique can be easily used by the clinician and improves the diagnostic accuracy of exercise testing.

Angina Pectoris↗