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Biomedical subjects

L Grigg

Publications and source records attributed to L Grigg.

15 recordsLinked to original sources
PubMed2002

Clinical features of Fabry's disease in Australian patients.

BACKGROUND: Anticipating the prospect of specific treatment, we studied a large group of Australians with Fabry's disease. AIMS: We aimed to: (i) document the clinical features of Fabry's disease in Australian patients, (ii) test the hypothesis that clinical features vary with specific mutation and blood group and (iii) assess small-fibre peripheral nerve function. METHODS: A questionnaire was forwarded to all Australian patients known to us. Patients were invited to attend for clinical, renal cardiac, ophthalmological and neurological assessment. RESULTS: Sixty-seven patients (29 men and 38 women) from 18 families participated. Diagnosis in index cases was delayed by > or = 10 years in nearly all families. Common clinical features are: (i) episodic acroparaesthesia (100% of hemizygotes; 53% of heterozygotes), (ii) anhydrosis (93%; 1%), (iii) characteristic rash (93%; 13%), (iv) renal disease (69%; 21%), (v) ischaemic heart disease (28%; 26%), (vi) palpitations (62%; 29%), (vii) mitral valve murmurs (37%; 23%) and (viii) premature cerebrovascular disease (31%; 5%). Ophthalmic findings of cornea verticillata (96%; 76%) and anterior cataract (48%; 14%) were common. Findings were variable within and between families. In women, anhydrosis reliably predicts the presence of significant Fabry's renal disease. Small nerve fibre testing using quantitative sensory testing was clearly abnormal in 95% of male patients, and in those female patients with paraesthesiae. CONCLUSIONS: Symptoms of anhydrosis, acroparaesthesiae, rash and renal disease suggest diagnosis of Fabry's. Women are commonly symptomatic, and the advent of therapy highlights the practical advantage of earlier diagnosis.

Adult↗
PubMed2001

Impaired cardiac functional reserve and left ventricular hypertrophy in adult sheep after prenatal dexamethasone exposure.

We have shown that exposure of pregnant ewes to dexamethasone (11.5 mg/d for 2 days) at 27 days of gestation (term, 150 days) led to increased blood pressure and cardiac output in adult offspring. In this study, we hypothesized that dexamethasone-induced hypertension is associated with left ventricular hypertrophy and a reduced cardiac functional reserve (CO(max-0)). Six control animals (group C) and five dexamethasone-exposed animals (group D) were volume-loaded with Hemaccel until the wedge pressure was 13 mm Hg (baseline). The wedge pressure was held constant during an infusion of dobutamine at incremental doses (0.4 to 12 microgram/kg/min) while blood pressure and cardiac output were measured. The same protocol was repeated in each animal 5 days later under mild general anesthesia (1.5% isoflurane), when transthoracic echocardiography (M-mode) was obtained. Group D showed a reduced CO(max-0) in response to dobutamine during both conscious (89+/-22 versus 150+/-25 mL/kg/min in control; P<0.01) and anesthetized states (91+/-38 versus 156+/-56 mL/kg/min in control; P<0.05). Reduced CO(max-0) in group D was associated with higher left ventricular mass index compared with group C (2.6+/-0.67 versus 1.8+/-0.51 g/kg; P<0.05). In addition, group D showed a reduced cardiac contractility reserve (FS(max-0)) in response to dobutamine (21+/-22% versus 54+/-34% in group C; P<0.05). An impaired cardiac functional reserve in group D was associated with increased left ventricular type I collagen content. In conclusion, brief prenatal exposure to dexamethasone led to the development of hypertension, left ventricular hypertrophy, and reduced cardiac functional reserve in adult life.

Animals↗
PubMed1998

Transcranial Doppler detection of microemboli during percutaneous transluminal coronary angioplasty.

BACKGROUND AND PURPOSE: The use of percutaneous transluminal coronary angioplasty (PTCA) to treat coronary artery disease is now commonplace. The occurrence of microemboli during invasive procedures such as cardiac angiography and bypass surgery is well documented, although neurological complications are relatively uncommon. To date, no investigation has been undertaken of the frequency or nature of microemboli occurring during PTCA or of the correlation with aortic atheroma. METHODS: Twenty patients having elective PTCA underwent examination by transcranial Doppler ultrasonography (TCD) to detect left middle cerebral artery microemboli occurring during the procedure. Blinded off-line analysis correlated microembolic signal counts on TCD with the components of each stage of the PTCA. Patients later underwent transesophageal (TEE) echocardiography, with measurements made of the thickness of the intima and atheroma in the ascending and descending thoracic aortic arch by cardiologists blinded to the TCD results. RESULTS: A total of 973 microembolic signals were detected (mean+/-SD, 48.7+/-36.7 per patient); 196 (20%) occurred on movement of the PTCA catheter and wire around the aortic arch, 84 (9%) with other PTCA catheter-associated movements, and 679 (70%) in association with injection of solutions (eg, saline and contrast). Mean signal counts during contrast injection were significantly greater than during the other 3 phases (P<0.001). No neurological events occurred in the study. Although not statistically significant, there was a trend toward greater microembolic signal counts with the number of times the catheter was passed around the aortic arch and the amount of arch atheroma detected by transesophageal echocardiography. CONCLUSIONS: Microemboli detected on TCD are a common occurrence during PTCA but are largely asymptomatic. The majority of microembolic signals are most probably gaseous in origin and do not appear to be related to the extent of aortic atheroma or to clinical events.

Aged↗
PubMed1998

Assessment of thoracic aortic atheroma by echocardiography: a new classification and estimation of risk of dislodging atheroma during three surgical techniques.

A new classification is described to improve precision of thoracic atheroma reporting. In 68 patients, the thoracic aorta was screened with epiaortic and transesophageal echocardiography. The thoracic aorta is divided into 6 zones corresponding to sites of aortic manipulation. Zones 1-3, proximal, mid and distal ascending aorta, Zones 4-5, proximal and distal arch and Zone 6, proximal descending aorta. Each zone is further sub-divided into anterior, left lateral, posterior and right lateral quadrants. There is a marked increase in moderate and severe atheroma between Zones 1-3 and Zone 4-6 (p<0. 001). There is a difference in atheroma by quadrant with the anterior the most frequent. (p<0.001) Once the grade and location of atheroma was classified, a comparison of the estimation of risk of dislodging atheroma during three surgical methods for care, was performed. Of 50 quadrants of atheroma, the composite arterial pedicle Y graft CABG would manipulate 5, Aortocoronary CABG with single aorta cross clamp, 16, and Aortocoronary CABG with aortic partial occlusion clamp, 21. This classification of 6 zones and 4 quadrants within each zone will increase the precision of atheroma reporting and allow better comparison of stroke reduction interventions.

Aged↗
PubMed1998

Screening the thoracic aorta for atheroma: a comparison of manual palpation, transesophageal and epiaortic ultrasonography.

UNLABELLED: Accurate detection of atheroma within the thoracic aorta is an important part of most stroke prevention strategies in cardiac surgery. The thoracic aorta was divided into six zones corresponding to sites of surgical manipulation. Zones 1-3, proximal, mid and distal ascending aorta, zones 4-5, proximal and distal arch and zone 6, proximal descending aorta. This study compares the accuracy of atheroma detection by manual palpation, epiaortic (EPI) and transesophageal (TEE) ultrasonography in 70 patients. RESULTS: Using EPI as the reference method for zones 1-4, 14/70 patients were identified with moderate or severe atheroma. The frequency of atheroma was age related with the youngest at 55 years. Compared with EPI, manual palpation correctly detected moderate or severe atheroma in 7/14 patients (p=0.0058) and TEE in only 4/14 patients (p= 0.0002). For TEE, adequate imaging was only obtained in 41/70 in zone 3 and 30/70 in zone 4. Adequate imaging of zones 5-6 was obtained in all patients using TEE. Of 68 patients with adequate imaging of all zones, 36 had moderate or severe atheroma in zones 5-6. The positive predictive value for zones 1-4 based on atheroma in zones 5-6 was 39%. Of 32 patients with nil or mild atheroma in zones 5-6, only 1 had moderate or severe atheroma in zones 1-4 (negative predictive value 94%). CONCLUSION: Manual palpation and TEE are inaccurate methods of atheroma detection in zones 1-4. Epiaortic ultrasonography is recommended for all patients undergoing cardiac surgery, although the yield will be low for patients < 50 years of age or if there is nil or mild atheroma detected by TEE in zones 5-6.

Aged↗
PubMed1994

Permanent ventricular pacing via the great cardiac vein.

Two cases of left ventricular pacing via the great cardiac vein are presented. A 64-year-old female with a mechanical prosthetic tricuspid valve and slow atrial fibrillation had a failed attempt at pacing from the middle cardiac vein. In a 58-year-old male with hypertrophic obstructive cardiomyopathy and bradycardia tachycardia syndrome, transvenous permanent pacing could not be achieved via the right ventricle or middle cardiac vein. In both cases, successful pacing via the great cardiac vein was achieved but with an elevated stimulation threshold. These cases illustrate an alternate transvenous route when difficulties occur using standard ventricular pacing sites.

Atrial Fibrillation↗
PubMed1990

Doppler echocardiography assessment of prosthetic heart valves.

Transthoracic Doppler echocardiography is an accurate noninvasive method for the evaluation of prosthetic valve function. The flow characteristics and pressure gradients of normally functioning mechanical and bioprosthetic valves have been, in general established. Normal functioning mitral valve prostheses have a valve area greater than 1.8 cm 2 with the St. Jude valve having the largest effective valve area and normally functioning aortic prosthetic valves have a peak instantaneous gradient of less than 45 mmHg, with the Starr-Edwards valves (Starr-Edwards, Irvine CA) showing the highest gradients. The incidence of minimal or mild regurgitation is approximately 15% to 30% in the mitral position and 25% to 50% in the aortic position, with the higher incidence of regurgitation seen with mechanical compared to bioprosthetic valves. Transthoracic Doppler echocardiography can accurately detect patients with prosthetic valvular stenosis. The presence of prosthetic aortic regurgitation can also generally be accurately assessed, except in the presence of both prosthetic aortic and mitral valves. Assessment of prosthetic mitral regurgitation remains limited due to significant attenuation of the ultrasound beam by the prosthesis and the frequent underestimation of severity of regurgitation. Other limitations of transthoracic studies include assessment of leaflet morphology, detection of vegetations and valve abscesses, and differentiation between valvular and paravalvular regurgitation.

Bioprosthesis↗
PubMed1988

The role of permanent pacing after anterior myocardial infarction complicated by transient complete atrioventricular block.

A randomised study was performed to assess the influence of prophylactic permanent pacing on the incidence of late sudden death in patients surviving transient complete atrioventricular block with acute anterior myocardial infarction. Fourteen patients were studied, of whom ten died within two years, confirming the high overall late mortality in this group. The deaths included eight of the nine paced patients, of whom seven died suddenly. We conclude that prophylactic permanent pacing is not warranted in patients surviving transient complete atrioventricular block with acute anterior myocardial infarction.

Adult↗
PubMed1988

The porous titanium steroid eluting electrode: a double blind study assessing the stimulation threshold effects of steroid.

A transvenous pacing lead with a porous electrode which slowly elutes the steroid, dexamethasone sodium phosphate, has been developed. Previous investigations show low and constant stimulation thresholds persisting over at least the first two years post-implantation. As it is not known whether this low threshold results from the steroid or electrode configuration, a double blind study was designed to compare the same electrode configuration with and without steroid over a 2-year follow-up period. There were ten patients in each group with similar age, sex, indications for pacing and implantation data. Regular measurements of postoperative pulse duration thresholds were performed using a customized VVIM pulse generator programmed to 1.5 V output. For the first two days post-implantation, there were no statistical differences in the pulse duration thresholds between the two pacing leads. From 2 weeks to 2 years the pulse duration thresholds for the steroid leads remained almost constant, whereas the leads without steroid showed a typical rise. The difference in pulse duration thresholds between the two groups of leads from two weeks onwards confirmed that it was the steroid rather than the electrode configuration which prevented the rise in chronic stimulation threshold.

Aged↗
PubMed1986

Is an accurate verbal language necessary for heart rate discrimination?

Three groups of subjects were required to discriminate levels of cardiac function over three sessions. Two groups were required to detect in which of two contiguous 4-sec periods their heart rate (HR) was slowest. One of these groups was given knowledge of results concerning the correctness of their decisions. Their performance improved significantly. The other group was not given knowledge of results and their performance hovered around chance level. The third group was told to detect the period in which their heart rate was fastest, but they were told 'correct', via knowledge of results, only if they had picked their slowest rate. Their performance was inferior to the knowledge of results group, but superior to the no-knowledge group. They showed, however, little evidence of improved performance over sessions. The results are discussed in terms of a verbal labelling control of required discriminations.

Adult↗
PubMed1984

Heart rate discrimination and heart rate control: a test of Brener's theory.

Three experiments were conducted to examine predictions from Brener's theory regarding the relationship between autonomic discrimination and autonomic control. Experiment 1 examined the possibility that training subjects to discriminate their heart rates would enhance their skill at controlling that response. Twenty subjects participated in two sessions during which one group of 10 subjects received training (knowledge of results) on the Ashton discrimination technique. The second group performed the discrimination task but received no training. All subjects then took part in a third session of heart rate (HR) control (both increase and decrease) where half of each of the aforementioned groups received feedback during the control task, while the other half performed the HR control task without feedback. Results indicated that for the control of both HR increases and decreases, there was no significant difference between those subjects trained to discriminate their HR, and those who had received no training to discriminate HR. The second experiment investigated the hypothesis that training subjects with feedback to control their HR would enhance their capacity to discriminate their heart activity. Ten subjects participated in two sessions of HR control during which half the subjects received feedback training to increase HR. During a third session, all subjects underwent a test of discrimination ability using the Ashton technique, and no knowledge of results regarding performance was provided. Results confirmed the hypothesis. The final experiment in the series investigated the discrimination/control relationship within a problem-solving framework and used 20 subjects. Results confirmed the hypothesis that subjects forewarned at the time of discrimination training that a heart rate control task was to follow would perform better than 10 subjects receiving no forewarning of the task objective. This effect took place independently of cardiac discrimination ability. A second finding from this experiment was that subjects trained to discriminate heart rate were better able to increase heart rate than untrained subjects. This result contradicts that of Experiment 1, and reasons for this anomaly are discussed in detail.

Adolescent↗