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Biomedical subjects

A Sweeney

Publications and source records attributed to A Sweeney.

At least 37 records · Page 2Linked to original sources
PubMed1995

Reduced left ventricular systolic pump performance and depressed myocardial contractile function in patients > 65 years of age with normal ejection fraction and a high relative wall thickness.

We studied the relation between relative wall thickness, left ventricular systolic pump performance, and myocardial contractile function in 77 older patients with normal ejection fraction who were free of valvular and myocardial ischemic disease. Group 1 comprised 49 patients with relative wall thickness > or = 0.45; group 2 (n = 28) had normal relative wall thickness. Pump performance was characterized by stroke volume index, cardiac index, and stroke work; myocardial function was characterized by midwall shortening and circumferential stress versus shortening relations. Group 1 patients had lower end-diastolic volume (83 +/- 3 vs 124 +/- 5 ml, p < 0.05), cardiac index (2.6 +/- 0.2 vs 3.5 +/- 0.1 L/min/m2, p < 0.05), and stroke work/100 g left ventricular mass (43 +/- 2 vs 53 +/- 3 g-m/100 g, p < 0.005). Although there was no significant difference with regard to ejection fraction or fractional shortening at the endocardium, fractional shortening at the midwall was significantly lower in group 1 than in group 2 (16 +/- 1% vs 19 +/- 1%, p < 0.005). This lower value for midwall shortening was observed despite lower values for endsystolic stress, implying decreased myocardial contractile function. Lower stroke volume index in group 1 patients, likely due to small chamber size, was not offset by increased heart rate, resulting in a low-normal cardiac index; in 33% of group 1 patients, cardiac index was < 2.2 L/min/m2, indicating reduced pump performance. Our data indicate an abnormality in pump performance and myocardial function in patients who have high relative wall thickness and normal ejection fraction.

Age Factors↗
PubMed1995

The management of epilepsy in children: the role of the clinical nurse specialist.

Epilepsy in children is frequently accompanied by learning, behavioural and psychological difficulties. These difficulties may be compounded by the ignorance and stigma which exists within the community health care and education services. The management of epilepsy in children therefore extends far beyond the use of antiepileptic drugs and must address these additional problems. The establishment of a nurse specialist service in paediatric epilepsy within our hospital has provided a more satisfactory and comprehensive management of these children and, in addition, has facilitated a close liaison with schools, community health personnel and support groups; as a result this has dispelled much of the local ignorance, misunderstanding and stigma surrounding epilepsy.

Child↗
PubMed1995

Lorazepam versus diazepam in the acute treatment of epileptic seizures and status epilepticus.

Lorazepam was compared with diazepam for the treatment of acute convulsions and status epilepticus in 102 children in a prospective, open, 'odd and even dates' trial. Convulsions were controlled in 76 per cent of patients treated with a single dose of lorazepam and 51 per cent of patients treated with a single dose of diazepam. Significantly fewer patients treated with lorazepam required additional anticonvulsants to terminate the seizure. Respiratory depression occurred in 3 per cent of lorazepam-treated patients and 15 per cent of diazepam-treated patients. No patient who received lorazepam required admission to the intensive care unit for either respiratory depression or persisting status epilepticus. Rectally administered lorazepam appeared to be particularly valuable (100 per cent efficacy) when venous access was not possible.

Administration, Rectal↗
PubMed1992

Color Doppler mapping of aortic regurgitation in aortic stenosis: comparison with angiography.

Color flow Doppler mapping has become the principal noninvasive method used for the qualitative grading of aortic regurgitation (AR). However, the performance of the color Doppler method in patients with AR accompanying aortic stenosis (AS) has not been studied. We therefore compared results of color Doppler and semiquantitative angiographic grading of AR in 32 patients with AS (mean valve area = 0.7 cm2) undergoing supravalvular aortography in the course of cardiac catheterization. Color Doppler demonstrated AR in all 27 patients who had AR by aortography. As expected, neither the maximal jet area nor the jet length discriminated patients by angiographic grade. The best correlation between color Doppler and aortography occurred when the ratio of maximal jet height (JH) to left ventricular outflow tract (LVOT) height was used to grade AR on a scale of 0-4. Four of 5 patients without AR by aortography had either absent or grade 1 AR by color Doppler. Although there was considerable overlap of color Doppler grades in patients with 1+ AR by aortography, grade 3 or 4 AR by color Doppler was always associated with III+ or IV+ AR by aortography. Thus, color Doppler sensitively depicts AR in patients with AS, and the ratio of JH to LVOT height by color Doppler correctly identifies patients with III+ or IV+ AR by aortography. Methods for distinguishing among milder grades require further evaluation.

Aortic Valve↗
PubMed1992

Abnormal left ventricular intracavitary flow acceleration in patients undergoing aortic valve replacement for aortic stenosis. A marker for high postoperative morbidity and mortality.

BACKGROUND: We examined the clinical and echocardiographic characteristics of patients undergoing aortic valve replacement for aortic stenosis whose continuous wave Doppler studies showed abnormal intracavitary flow acceleration. METHODS AND RESULTS: The clinical and Doppler echocardiographic records of 53 consecutive patients undergoing aortic valve replacement for aortic stenosis were reviewed. Doppler echocardiography was performed at a mean of 6.6 days (range, 0-22 days) after surgery. Thirteen patients (group 1) had a dagger-shaped high-velocity systolic flow signal indicative of abnormal intracavitary flow acceleration on their postoperative Doppler study; group 2 comprised 40 aortic stenosis patients who underwent aortic valve replacement but had no postoperative evidence of abnormal intracavitary flow acceleration. Group 1 postoperative abnormal intracavitary flow velocities ranged from 1.8 to 6.8 m/sec (mean, 4.9 +/- 0.9 m/sec): Resulting dynamic gradients ranged from 10 to 184 mm Hg (mean, 104.6 +/- 32 mm Hg). Compared with group 2, group 1 patients had a distinctive ventricular geometry with more-pronounced hypertrophy, smaller cavities, and higher ejection fraction. Systolic anterior motion of the mitral valve did not accompany abnormal intracavitary flow acceleration in any patient. Six of 13 group 1 patients suffered postoperative hemodynamic compromise characterized by severe hypotension despite adequate pulmonary capillary wedge pressures; group 1 postoperative mortality was significantly greater than that seen in group 2 patients (38% versus 12%, p less than 0.05). CONCLUSIONS: Abnormal intracavitary flow acceleration after aortic valve replacement for severe aortic stenosis is associated with a distinctive ventricular geometry and supernormal systolic function but not systolic anterior motion of the mitral valve. Such flow acceleration appears to be a marker for increased postoperative morbidity and mortality. Preoperative and postoperative Doppler echocardiography may be useful in risk stratification and guiding therapy.

Aged↗
PubMed1992

A comparison of two-dimensional echocardiography vs carotid duplex scanning in older patients with cerebral ischemia.

BACKGROUND: To determine the relative value of two-dimensional (2D) echocardiography vs carotid duplex scanning and to devise an optimal, cost-effective diagnostic approach for older patients with cerebral ischemia, 68 consecutive patients in sinus rhythm who suffered focal cerebral ischemia were studied. All patients underwent 2D echocardiography and carotid duplex scanning in addition to routine clinical evaluation. METHODS: Twenty-five of 68 patients had Q-wave myocardial infarction by electrocardiography; nine (36%) of these 25 had left ventricular mural thrombi demonstrated by 2D echocardiography. In contrast, none of 43 patients without Q-wave myocardial infarction had clinically unsuspected findings diagnosed by 2D echocardiography. Duplex scanning, however, identified significant, abnormal findings in the carotid artery ipsilateral to the involved cerebral hemisphere in 23 patients (34%). CONCLUSIONS: Thus, in older patients in sinus rhythm who suffer a cerebral ischemic event, carotid duplex scanning has a higher diagnostic yield than 2D echocardiography and appears to be a more cost-effective initial test. Our data suggest that in patients with carotid distribution cerebral ischemic events and no obvious cardiac source for emboli by history and physical examination, 2D echocardiography should be limited to those with evidence of Q-wave myocardial infarction by electrocardiography; such management should optimize diagnostic yield and cost effectiveness.

Aged↗
PubMed1990

Asymmetric short-chain phosphatidylcholines: defining chain binding constraints in phospholipases.

Several short-chain asymmetric lecithins with a total of 14 carbons in the acyl chains (ranging from 1-lauroyl-2-acetylphosphatidylcholine to 1-hexanoyl-2-octanoylphosphatidylcholine) have been synthesized and characterized. The specific activities of phospholipase A2 from cobra venom, phospholipase A2 from porcine pancreas, and phospholipase C from Bacillus cereus toward these lecithins as micelles have been determined. The results of these kinetic studies allow the definition of hydrophobic binding requirements in the active sites of these water-soluble phospholipases. For phospholipase C, with the exception of monomyristoylphosphatidylcholine, each of the asymmetric short-chain lecithins exhibits high activity, comparable to the 14-carbon symmetric short-chain species, diheptanoylphosphatidylcholine. Therefore, for phospholipase C, in addition to the acyl linkages, only a certain degree of hydrophobicity in the fatty acyl chains is requisite for substrate binding and appreciable hydrolysis; there is no chain specificity. The activity of phospholipase A2 from cobra venom toward the same asymmetric lecithins is quite different. As the sn-2 chain lengthens, activity is increased to a maximum for diheptanoyl-PC. Further increase in the number of carbons in the sn-2 chain has no effect on hydrolysis rates. For this enzyme, seven carbons in the sn-2 chain are necessary for optimal activity. In contrast, porcine pancreatic phospholipase A2 activity shows very little dependence on sn-2 chain length.

Animals↗
PubMed1989

The biochemical composition of hemodynamically stressed vascular tissue: the insoluble elastin of experimental arteriovenous fistulae.

Arteriovenous fistulae between the external jugular vein and the common carotid artery were surgically fashioned in eight sheep. The altered hemodynamics produced morphological changes similar to those observed in human atherosclerosis. The elastica is a major mural component and undergoes considerable structural variation during lesion development. The most significant biochemical changes in the elastin occur in the experimental vein region. These include a quantitative loss particularly in the midregion of the vein and a decrease in the concentration of up to 20% of the crosslinks (desmosine and isodesmosine). There is an increase in the cholesterol content of the elastin purified from both experimental artery and vein. The bound phospholipid was higher in the experimental artery and in the dilated experimental vein. There was a significant time-dependent loss of elastin in the stressed venous tissue.

Amino Acids↗
PubMed1978

Branchio-oto-renal dysplasia and branchio-oto dysplasia: two distinct autosomal dominant disorders.

Three families are presented, one with branchio-oto-renal dysplasia (BOR) and two with branchio-oto dysplasia (BO). The former syndrome is characterized by external ear malformations, cervical fistulae, mixed hearing loss and renal anomalies of varying severity. The latter syndrome differs in that there are no renal anomalies and that the sensorineural component of the hearing loss may be absent. The external ear malformations are quite variable in both syndromes. Evidence is presented which supports the idea that these two syndromes are not phenotypic variants of the same autosomal dominant mutation but distinct disease entities. The BOR syndrome appears to belong to a larger group of hereditary ear dysplasia-renal adysplasia syndromes that must be carefully ruled out in all patients with familial branchial arch malformations as well as in the parents and siblings of infants with "Potter facies" in the presence of auricular malformation and renal adysplasia.

Abnormalities, Multiple↗
PubMed1975

Symposium on sensorineural hearing loss in children: early detection and intervention. Genetic factors in deafness of early life.

One half of all cases of childhood deafness are genetically caused, and this proportion will become increasingly larger as other causes come under control. The mode of transmission of hereditary hearing loss may be dominant, recessive, or X linked. Many varieties of childhood deafness can be distinguished by their accompanying anomalies. Other types of hereditary deafness occur, without associated abnormalities. Certain of these types may be delineated by the mode of transmission, age of onset, stability or progression, and audiometric findings. Further research on delineation of nonsyndromic hearing loss in necessary if treatment of specific kinds is to become a reality. Research also is needed to detect the carrier state in recessive and X linked types of hearing loss. In the absence of means of prevention and treatment for most cases of hereditary deafness, genetic counseling remains the most valuable course.

Adolescent↗
PubMed1971

X-linked mixed deafness with congenital fixation of the stapedial footplate and perilymphatic gusher.

An X-linked syndrome characterized in males by profound mixed deafness, vestibular abnormalities, congenital fixation of the stapes and perilymphatic otorrhea on attempted stapedectomy has been documented in a large Caucasian kindred. Female heterozygotes have similar but milder audiologic abnormalities. The syndrome of congenital fixation of the stapes with perilymphatic gusher may be a relatively common form of X-linked deafness and is an important clinical entity because affected males may be significantly benefited by sound amplification.

Audiometry↗
PubMed1971

Evidence for autosomal recessive inheritance of the syndrome of renal tubular acidosis with deafness.

A four-year-old Caucasian male with well-documented renal tubular acidosis, first noted in early infancy, was found to have profound hearing loss causing delayed speech development. The parents were first cousins, and three male half-sibs, each by a different father, were not affected. The findings suggest that the syndrome of renal tubular acidosis with deafness is a distinct nosologic entity that is determined by an autosomal recessive gene.

Acidosis, Renal Tubular↗