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Biomedical subjects

M D Smith

Publications and source records attributed to M D Smith.

At least 613 records · Page 34Linked to original sources
PubMedDate not supplied

Quantification of mitral regurgitant volume by the color Doppler proximal isovelocity surface area method: a clinical study.

In vitro studies have demonstrated that regurgitant flow rate can be estimated by the color Doppler "proximal isovelocity surface area" (PISA) method. By applying the PISA method and continuity principle, we developed a formula to calculate mitral regurgitant volume: 2 pi r2.VN.FVI/Vo, where r = distance from the first jet alias to mitral leaflets, VN = aliasing velocity, FVI = flow velocity integral or regurgitant jet, and Vo = peak velocity through the regurgitant orifice. Doppler echocardiography was performed in 20 patients with mitral regurgitation. The mitral regurgitant volume was estimated by PISA and compared to cine ventriculographic grading. The results showed an increase in regurgitant volume by PISA compared with increasing angiographic grades of mitral regurgitation: 19 +/- 0.6, 18 +/- 5, 25 +/- 12, and 44 +/- 4 ml for grades 1+ to 4+, respectively (r = 0.77). Thus a formula developed from PISA is able to identify patients with a severe grade of mitral regurgitation and to provide an alternate approach to the noninvasive quantitation of mitral regurgitation.

Adult↗
PubMedDate not supplied

Three-dimensional echocardiography: limitations of apical biplane imaging for measurement of left ventricular volume.

A new three-dimensional echocardiographic system creates a "line of intersection" display to allow precise and known positioning of echocardiographic images. Our purpose was to determine whether use of the line-of-intersection display will improve positioning of the apical four-chamber and apical two-chamber views and thereby improve the agreement between estimates of left ventricular volume by apical biplane echocardiography and cineventriculography. Unguided and line of intersection-guided apical biplane views were obtained in 31 patients immediately before cardiac catheterization and single-plane cineventriculography. In 15 patients the line-of-intersection display was used to measure the position of the image plane in studies of unguided and guided methods. Linear regression and limits of agreement analysis were used to assess the agreement between cineventriculographic volumes and echocardiographic volumes determined from each set of images. The Wilcoxon test was used to compare guided and unguided image positioning. The line-of-intersection display improved four-chamber and two-chamber view positioning closer to the center of the ventricle and rotation closer to orthogonal positioning. Guided-image positioning was not able to correct displacement of the ultrasound beam anterior to the ventricular apex without deterioration of image quality in most patients. Despite improvements in image plane positioning, the agreement between echocardiographic and cineventriculographic volumes was unchanged. For end-diastole views, the unguided images had an r value = 0.84, standard error of the estimate of +/- 23.0 cc, and limits of agreement of +/- 62.4 cc. Corresponding values for the guided images at end diastole were r = 0.85, standard error of the estimate of +/- 22.9 cc, and limits of agreement of +/- 60.8 cc. At end systole the unguided results were r = 0.91, standard error of the estimate of 16.8 cc, and limits of agreement of +/- 52.2 cc. The line-of-intersection guiding of image plane positioning can improve apical image positioning but does not improve the agreement between apical biplane echocardiographic and cineventriculographic left ventricular volumes. The optimal apical imaging window is frequently occluded by the rib cage, resulting in a decrease in image quality. This reduction of image quality, combined with assumptions of left ventricular geometry, limit the accuracy of estimates of left ventricular volume from apical biplane echocardiography.

Adult↗
PubMedDate not supplied

Comparison of transesophageal color flow Doppler imaging of normal mitral regurgitant jets in St. Jude Medical and Medtronic Hall cardiac prostheses.

Transesophageal color flow Doppler imaging of mitral mechanical prostheses is now widely used. This method eliminates the frequent problems of acoustic shadowing and flow masking that are commonly seen with a transthoracic Doppler study of mechanical mitral prostheses. Transesophageal color flow Doppler imaging was performed postoperatively in seven patients who had received St. Jude Medical mitral prostheses (St. Jude Medical, Inc., St. Jude, Minnesota) and in six patients who received Medtronic Hall mitral valves (Medtronic, Inc., Minneapolis, Minnesota). Maximal systolic regurgitant jet length and area determinations were obtained in all patients. A comparison of maximal jet lengths and areas for each type of mechanical prosthesis demonstrated that the Medtronic Hall prostheses produced longer maximal jet lengths (p = 0.0001) and larger jet areas (p = 0.0009) than those produced by the St. Jude Medical mitral valves. Medtronic Hall prostheses produce a large centrally directed jet, whereas St. Jude Medical prostheses typically generate three smaller jets. Recognition of these differences in transesophageal color flow Doppler images in these commonly used cardiac valve prostheses is necessary to avoid misinterpretation of the normally large systolic regurgitant jet of the Medtronic Hall prosthesis as representing prosthetic dysfunction.

Adult↗
PubMedDate not supplied

Three-dimensional echocardiographic volume computation: in vitro comparison to standard two-dimensional echocardiography.

Two-dimensional (2D) echocardiographic methods for quantitative left ventricular volume computation have been shown to have a low predictive accuracy and reproducibility. To address the problem of geometric assumptions and image plane positioning errors inherent in 2D echocardiography, three-dimensional (3D) echocardiographic systems have been constructed that provide spatial registration and display of transducer-image position and orientation. Although 3D echocardiography has been shown to accurately measure volume in vitro and in vivo, only preliminary data exist demonstrating its superiority over standard 2D echocardiography. We calculated the volume of 30 water-filled latex balloon phantoms of varying size (40 to 200 ml) and shape using each method. Fifteen phantoms were nondistorted (ellipsoid or pear shaped); 15 were symmetrically distorted (dumbbell shaped). Although both 2D and 3D echocardiography showed an excellent correlation to the true volume (r = 0.97 and 0.99, respectively), the standard error of the estimate for 2D echocardiography was twofold larger than for 3D echocardiography (SEE = 6.7 ml and 3.52 ml, respectively). The true volume was slightly underestimated by 3D echocardiography (-2.83 ml), whereas 2D echocardiography overestimated a similar amount (+2.87 ml). The accuracy and variability for 2D echocardiography were significantly poorer (5.22% +/- 5.66% and 5.29% +/- 5.6%, p = 0.001 and 0.002, respectively) as compared with 3D echocardiography (3.7% +/- 2.65% and 2.65% +/- 1.9%, respectively). We conclude that 3D echocardiography with guided image plane positioning and a novel algorithm for volume computation (polyhedral surface reconstruction) achieves significantly more accurate and reproducible results than conventional 2D echocardiography with the modified Simpson's rule.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Volume↗
PubMedDate not supplied

Massive air embolus to the left ventricle: diagnosis and monitoring by serial echocardiography.

Air embolization is an unusual but potentially dangerous complication in left heart catheterization. Microbubbles can be detected with two-dimensional echocardiography, which is often used for this purpose during open heart and bypass surgeries. Permanent neurologic sequelae and hemodynamic collapse can result from embolization of air bubbles to the cerebral and coronary circulations, respectively. Hyperbaric oxygen is the treatment of choice for cerebral air embolization. We present a 39-year-old man who had air embolization during left ventriculography in the form of a large pocket of "pooled" air. The patient was treated with conservative therapy successfully. Two-dimensional transthoracic echocardiography was used to document the presence of the air and follow its dissolution.

Adult↗
PubMedDate not supplied

Scleroderma in South Australia: epidemiological observations of possible pathogenic significance.

BACKGROUND: Scleroderma is an autoimmune disorder of unknown cause. Previous epidemiological studies have suggested some regional clustering and associations with occupations involving exposure to silica dusts and hydrocarbons. AIMS: To determine: (i) prevalence and incidence of scleroderma in South Australia (SA), a state with a stable population living in well-defined urban, rural and industrial regions, (ii) hospital separation rates, (iii) cumulative survival rates, (iv) gender and disease subclassification, (v) geographical residency and occupations, (vi) familial associations and (vii) age at onset versus age-specific incidence rate. METHODS: Creation of the South Australian Scleroderma Register (SASR) to identify demographics and clinical and serological features of all scleroderma patients resident in SA. RESULTS: Scleroderma occurs in South Australia with a point prevalence of 23 per 10(5) and an incidence of approximately 1/15th of this. However, this prevalence is high compared with other regional world studies. Scleroderma is predominantly a female disease, with most patients having the limited form of scleroderma characterized by the presence of the anticentromere antibody and a mean survival of 27.6 years. In contrast, diffuse scleroderma is a less benign disease occurring at an early age of onset and has a mean survival of 9.6 years. Scleroderma occurs throughout SA without regional localization. Weak associations are seen in males, but not females, with occupations involving possible environmental exposure to silica or hydrocarbons. Scleroderma rarely occurs in families. CONCLUSION: No strong genetic or environmental influences were found to account for the relatively common occurrence of scleroderma in SA. The age at onset versus age-specific incidence curve suggests that scleroderma can be considered as a stochastic illness involving a number of random events occurring in a predisposed population. These random events may involve mutations of pivotal somatic genes.

Age of Onset↗
PubMedDate not supplied

Scleroderma renal crisis: poor outcome despite aggressive antihypertensive treatment.

BACKGROUND: Scleroderma renal crisis (SRC) is a rare but feared complication of scleroderma. Angiotensin--converting enzyme (ACE) inhibition has significantly improved survival, but it is unknown whether prophylactic ACE inhibitors will prevent this complication. AIMS: To determine: (i) the frequency of SRC in our cohort of well-characterized scleroderma patients resident in South Australia, (ii) any predisposing clinical and serological features, (iii) median disease duration at which SRC occurs, (iv) possible precipitants, (v) disease outcome, and (vi) whether patients were taking ACE inhibitors prior to onset of SRC. METHODS: Systematic review of the clinical course of all patients registered on the South Australian Scleroderma Register. RESULTS: SRC occurred in 16 patients. This constituted 2.8% of a total scleroderma cohort and 15% of the diffuse scleroderma cohort identified in South Australia. All 16 patients had diffuse cutaneous scleroderma. SRC occurred at a median disease duration of 15 months (range 1 week-11 years). Disease outcome was poor (five deaths, three requiring long-term dialysis and only two patients regaining a normal creatinine) despite aggressive antihypertensive treatment (including ACE inhibitors) in an intensive care or specialized renal unit. Two patients were later able to discontinue dialysis. Only two patients were taking small doses of ACE inhibitors prior to the onset of their SRC. The frequency of Scl-70 was decreased in the SRC group (P = 0.003). CONCLUSION: SRC is a rare event occurring in a small proportion of patients with diffuse scleroderma. The outcome of SRC was poor despite aggressive antihypertensive treatment. It is hypothesized that prophylactic ACE inhibition in susceptible patients might prevent or ameliorate this complication.

Adult↗
PubMedDate not supplied

Antibiotic misuse in two clinical situations: positive blood culture and administration of aminoglycosides.

Antibiotic use was examined among randomly and prospectively selected cohorts of 79 patients with a positive blood culture and 88 patients given aminoglycosides for a variety of reasons. Appropriateness of antibiotic use was judged daily for each agent according to specific criteria of misuse. For patients with a positive blood culture, 14.3% of antibiotic-days were judged inappropriate in some regard, while for patients given aminoglycosides, 10.2% of antibiotic-days were thought to be inappropriate. The patterns of misuse were similar for the two groups despite disparate selection criteria. The unnecessary use of antibiotics was the single most common type of misuse in both groups, but errors in dosing collectively accounted for nearly one-half of antibiotic misuse. These results suggest that a variety of factors are responsible for misuse of antibiotics. Although the data presented do not allow conclusions about the optimal methods for control of antibiotic misuse, they imply that a multifaceted approach is probably required.

Ampicillin↗
PubMedDate not supplied

Monoarticular gout following trauma: MR appearance.

We report a case of gout with monoarticular tophaceous involvement of the proximal interphalangeal joint of the middle finger, emphasizing MR findings. To the best of our knowledge, the MR appearance of gout is not commonly known.

Arthritis, Gouty↗
PubMedDate not supplied

Eastern massasauga rattlesnake bites.

The Eastern massasauga rattlesnake is native to many Midwestern states. Although this rattlesnake is smaller in size than many other pit vipers, envenomation can still produce significant morbidity, particularly in children. Children bitten by Eastern massasauga rattlesnakes appear to do well with treatment programs consisting primarily of antivenom and blood component replacement.

Adolescent↗
PubMedDate not supplied

Antibodies to heat shock protein 65 kD in type 1 diabetes mellitus.

To determine whether antibodies to mycobacterial heat shock protein of 65 kD molecular weight (hsp 65) could be important in the pathogenesis of Type 1 diabetes we tested patients before and at diagnosis of diabetes, as well as patients with rheumatoid arthritis. Using ELISA, increased hsp 65 antibodies were detected in 2 of 8 pre-diabetic twins, 1 of 13 newly diagnosed untreated diabetic patients and 3 of 10 rheumatoid arthritis patients. Levels of hsp 65 antibodies in pre-diabetic twins, median (range), 0.25 (0.104-1.904) and newly diagnosed diabetic patients (mean +/- SD) (0.299 +/- 0.220), did not differ significantly either from each other or from their control subjects (0.134 +/- 0.123). In contrast, levels of hsp 65 antibodies in rheumatoid patients (0.59 +/- 0.42) were significantly higher than in their control subjects (0.21 +/- 0.18; p = 0.02). Of twins studied prospectively before diagnosis, at diagnosis but before insulin treatment, and soon after diagnosis, three of four had hsp 65 antibodies at some stage. We conclude that serological immunity to mycobacterial hsp 65 can occur in Type 1 diabetes, but it is neither a characteristic nor a specific feature of the disease.

Adult↗
PubMedDate not supplied

Gestational trophoblastic neoplasms.

Gestational trophoblastic neoplasms have evolved from one of the most rapidly fatal malignancies to potentially one of the most curable, but these diseases have devastating emotional effects on the victims. Etiology, epidemiology, pathophysiology, diagnosis, and medical treatment are reviewed. Numerous nursing implications are discussed using crisis theory. A nursing care plan, based on nursing diagnosis, is outlined with specific nursing actions defined.

Chorionic Gonadotropin↗
PubMedDate not supplied

Comparison of ofloxacin and metronidazole for the treatment of bacterial vaginosis.

The efficacy and safety of ofloxacin, 200 mg twice daily for 7 days, was compared with metronidazole, 400 mg twice daily for 7 days, for the treatment of bacterial vaginosis (BV). Diagnosis of BV was confirmed by at least 3 of the following 4 criteria: the presence of an abnormal vaginal discharge on examination, clue cells on microscopy of vaginal specimens, vaginal pH greater than 5.0 and a positive amine test. Vaginal specimens were examined for Mobiluncus spp, analysed for the succinate/lactate (S/L) ratio and cultured for Trichomonas vaginalis, Gardnerella vaginalis, Bacteroides spp. and Mycoplasma hominis. Patients were reviewed on completion of treatment (visit 2) and 14 days later (visit 3). The diagnosis of BV was accepted in 119 of 149 patients recruited, 60 of whom received treatment with ofloxacin and 59 received metronidazole. Sixty-two patients, 31 in each treatment group, completed the study. Diagnostic cure at visit 2 was significantly better in the metronidazole group with cure rates of 56% (metronidazole) vs 23% (ofloxacin) (P = 0.001); this was associated with higher eradication rates for G. vaginalis (100% vs 56%) and Bacteroides spp. (97% vs 49%). There were no significant differences between the two groups in clinical cure at either visit 2 or 3 or in diagnostic cure at visit 3. Both treatments were well tolerated. We conclude that metronidazole is likely to remain the first choice of treatment for BV but ofloxacin offers a safe and effective alternative.

Adolescent↗
PubMedDate not supplied

Post-concussion syndrome and the coping hypothesis.

Neuropsychological functioning and level of subjective symptomatology was assessed in 15 adults at 2 weeks, 1 month, and 3 months post-concussion. Performance by the concussion subjects was compared to the results obtained by a matched group of normal controls. At 2 weeks post-injury the concussion subjects had deficits in intellectual, attentional, memory, and language abilities. Visuospatial constructional abilities were relatively preserved. Concussed subjects also reported high levels of disturbance in affective, cognitive, and social functioning. By 3 months post-injury the concussed subjects were still displaying deficits in attentional and language functioning. The level of subjective symptoms reported by the concussed subjects was not significantly different from that reported by controls. Results provide some support for the 'coping hypothesis' explanation of post-concussion syndrome.

Adaptation, Psychological↗