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N R Grubb

Publications and source records attributed to N R Grubb.

At least 19 recordsLinked to original sources
PubMed2006

Wavelet transform analysis predicts outcome of DC cardioversion for atrial fibrillation patients.

The aim of this study was to examine whether wavelet transform analysis of the electrocardiogram (ECG) can improve the prediction of the maintenance of sinus rhythm in patients with atrial fibrillation (AF) after external DC cardioversion. We examined a variety of wavelet transform-based statistical markers as potential candidates for the prediction of patient status post-cardioversion. Considering a 'success' as a patient who remains in normal sinus rhythm for one month post cardioversion and 'failure' as a patient who does not, it was shown the proposed non-parametric classification system can achieve 89% specificity at 100% sensitivity using a non-parametric classification method.

Algorithms↗
PubMed2004

Surviving out of hospital cardiac arrest at home: a postcode lottery?

OBJECTIVE: To find out if the response time, distance travelled to scene, and geographical location affect survival from out of hospital cardiac arrest (OHCA). METHODS: Retrospective cohort study over 10 years, 1 December 1991 to 1 August 2001. Outcome and demographic data were obtained for 1956 OHCAs occurring at home, in the Lothians region, from the Heartstart Scotland database. Survival rates to hospital admission and discharge were examined by postcode district. RESULTS: Certain postcode areas were served by quicker response times and shorter journeys. The survival to admission rate was greater in those areas where the median response time was <10 minutes (13.5% versus 8.1%, p<0.05). There was greater survival to discharge in these areas but not significantly so (4.1% versus 3.2%, p = 0.42). Survival to admission was more likely in areas where the median distance travelled was <four miles (13.3% versus 9.7%, p<0.05) but not survival to discharge (4.0% versus 3.7%, p = 0.72). A close correlation between distance travelled and response time was shown (Pearson = 0.93, p<0.01), likewise between distance travelled and survival to admission (Spearman = -0.87, p<0.01). Certain areas, particularly those at greater geographical distance from ambulance dispatch points, were found to be associated with significantly lower survival to admission rates. CONCLUSIONS: Survival to admission from OHCA is strongly influenced by response time and distance travelled to the scene. The geographical location of an arrest can potentially influence survival to admission. Measures should be taken to strategically position ambulance dispatch points and to task the nearest geographically available vehicle to attend an OHCA.

Aged↗
PubMed2001

Psychological factors associated with delay in attending hospital following a myocardial infarction.

OBJECTIVE: There is wide variability in latency to attend hospital following a myocardial infarction (MI). The present study assessed possible psychological factors that may be implicated in delayed presentation. METHOD: Seventy-two patients who had experienced a confirmed MI were interviewed in hospital, 3-5 days post-MI. They completed a series of psychological measures of cardiac denial, cardiac threat, alexithymia, health locus of control, neuroticism and mood. RESULTS: Those patients who believed that they were having a heart attack sought help quicker than those who did not, and those who waited over 4 hours prior to seeking medical help had significantly lower scores on neuroticism, and higher scores on denial and health locus of control (chance). Confirmatory multiple regression analysis using an alternative estimate of delay in seeking help confirmed that health locus of control (chance) was the best predictor of delayed attendance. CONCLUSION: The present study confirms that the belief that one is having a MI is associated with prompt attendance, and additionally that the belief that health outcomes are largely due to chance factors is associated with delayed presentation following a MI. This delay could prove fatal. Modification of such beliefs may reduce response times and, thus, increase survival rates.

Denial, Psychological↗
PubMed2000

Chronicity of memory impairment in long-term out-of-hospital cardiac arrest survivors.

As a result of out-of-hospital defibrillation initiatives, many cities have an increasing population of out-of-hospital cardiac arrest survivors. We previously identified that one third of these patients suffer memory problems in the months after resuscitation. The pattern of memory impairment (impaired recall memory and intact recognition memory) is suggestive of hippocampal damage. In this study we followed up ten subjects who had previously been found to have memory impairment after their cardiac arrest. To assess the chronicity of this memory impairment, we re-tested memory function approximately 3 years after the index events. These subjects were compared with age and sex matched control subjects with previous myocardial infarction and no cardiac arrest. Memory was assessed using the Rivermead Behavioural Memory test (RBMT). To further assess recall and recognition memory we used the Doors and People test (DPT), which is specifically designed to identify deficits in these functions. RBMT scores declined significantly in both groups compared with the original assessment 8 months after cardiac arrest, possibly an effect of ageing-control group: mean (S.D.) 22.2 (1. 4)-18.4 (2.9); cardiac arrest group: 16.1 (2.7)-14.6 (4.4). The inter-group difference in RBMT score remained significant (P=0.001). DPT scores were poor in the cardiac arrest group (mean (S.D.) total 5.8 (2.8)), compared with the control group (10.8 (3.4)) who scored normally. Both recall and recognition memory were poor in the cardiac arrest group. We conclude that the memory deficits that we previously observed in cardiac arrest victims are persistent. Both recall and recognition memory are affected, implying that non-selective brain injury may be the mechanism.

Aged↗
PubMed2000

Memory function in patients with stable, moderate to severe cardiac failure.

BACKGROUND: Psychologic dysfunction is common in patients with heart disease. Patients with end-stage cardiac failure have cognitive dysfunction that can affect their ability to comply with complex treatment regimes. The prevalence of cognitive dysfunction in patients with stable, moderately severe cardiac failure is not known. The purpose of this study was to evaluate the prevalence of memory dysfunction in that population. METHODS: Twenty patients with previous myocardial infarction (MI), New York Heart Association class III or IV cardiac failure symptoms, and left ventricular ejection fraction (LVEF) <40% were studied. Twenty patients with previous MI, no heart failure symptoms, and LVEF >50% were studied as a control group. Memory function was assessed with the Rivermead Behavioural Memory Test and digit span test. Results were controlled for affective state and estimated premorbid intellectual function with the National Adult Reading Test. RESULTS: Patients with cardiac failure performed as well as controls in the memory test (mean [95% confidence intervals] score 18.2 [16.5-19.9] versus 19.7 [18.1-21.4] points, P =.20) and digit span test (10.1 [9.2-11.0] versus 11.0 [9.9-12.2] points). Affective symptoms were more prevalent among patients with cardiac failure. Estimated premorbid intellectual function appeared poorer in patients with cardiac failure (reading test score 24 [7-36] versus 32 [11-46] points). Memory test outcomes were not significantly affected after adjustment for these variables. CONCLUSIONS: Patients with prior MI and stable, moderately severe cardiac failure do not have significantly memory impairment. Memory dysfunction is not likely to interfere with rehabilitation or compliance with treatment regimes. Anxiety and depression, however, are relatively common in this group.

Aged↗
PubMed2000

Memory impairment in out-of-hospital cardiac arrest survivors is associated with global reduction in brain volume, not focal hippocampal injury.

BACKGROUND AND PURPOSE: More than 30% of out-of-hospital cardiac arrest (OHCA) survivors suffer significant memory impairment. The hippocampus may be vulnerable to hypoxic injury during cardiac arrest. The purpose of this study was to determine whether selective hippocampal injury is the substrate for this memory impairment. METHODS: Seventeen OHCA survivors and 12 patients with uncomplicated myocardial infarction were studied. OHCA survivors were divided into those with impaired and intact memory. Memory was assessed by use of the Rivermead Behavioural Memory Test and Doors and People Test. MRI was used to determine intracranial, whole-brain, amygdala-hippocampal complex, and temporal lobe volumes. Brain structure was also examined by statistical parametric mapping. RESULTS: Left amygdala-hippocampal volume was reduced in memory-impaired OHCA victims compared with control subjects (mean 3. 93 cm(3) and 95% CI 3.50 to 4.36 cm(3) versus mean 4.65 cm(3) and 95% CI 4.37 to 4.93 cm(3); P=0.002). Left temporal lobe and whole-brain volumes were also reduced. There were no differences in amygdala-hippocampal volume indexed against ipsilateral temporal lobe volume. Significant correlations were observed between total brain volume and Rivermead Behavioural Memory Test (r=0.56, P<0.05) and Doors and People Test (r=0.67, P<0.01) scores in OHCA survivors. Both recall and recognition were compromised in memory-impaired subjects. Statistical parametric mapping did not detect focal brain abnormalities in these subjects. Global cerebral atrophy was confirmed by qualitative assessment. CONCLUSIONS: Memory impairment in OHCA survivors is associated with global cerebral atrophy, not selective hippocampal damage. Rehabilitation protocols need to account for the global nature of the brain injury.

Aged↗
PubMed2000

Management of unstable angina.

Unstable angina is a common condition that presents a challenge to physicians because of its complex pathophysiology, and because of the high incidence of associated death and myocardial infarction. This article summarizes key strategies that can be employed in managing unstable angina and describes their interaction with the mechanisms that underpin the condition.

Adrenergic beta-Antagonists↗
PubMed1998

Effect of DC shock on serum levels of total creatine kinase, MB-creatine kinase mass and troponin T.

After successful resuscitation from cardiac arrest, it is important to identify whether the event has been triggered by a myocardial infarction, since this determines subsequent investigations and management. Previous studies have shown that biochemical indices of infarction become elevated after resuscitation in patients without myocardial infarction. This can lead to overdiagnosis of myocardial infarction in the post-arrest setting. The cause of the elevated enzyme levels is not known, but may involve electrical or mechanical injury to the heart during resuscitation. In this study we aimed to identify the effects of isolated direct current shock on serum levels of creatine kinase (CK), MB creatine kinase mass (MB-CK), and troponin T, and examined the relationships between enzyme levels and the dose of electrical energy used. Thirteen patients were studied who underwent DC cardioversion for atrial fibrillation. Serum was obtained for CK, MB-CK and troponin T estimation before and 10 min after cardioversion, at hourly intervals for 8 h, and 18 h after cardioversion. Total serum CK became significantly elevated after only 3 h and rose to a peak of 1294.4 IU l(-1) (P < 0.02) at 18 h. Post-shock CK levels were strongly correlated with total shock energy (r = 0.8, P < 0.01). Serum MB-CK was significantly elevated at 18 h among patients receiving total shock energies greater than 1000 J than in those receiving lower doses, reflecting a positive correlation (r = 0.64, P < 0.05) between shock energy and peak MB-CK level. Troponin T levels were not significantly elevated after cardioversion. In conclusion, total serum CK levels become significantly elevated early after cardioversion, suggesting rapid wash-out from injured skeletal muscle. MB-CK levels become significantly elevated in individuals receiving high energy shocks, probably due to release of small quantities of the CK-MB isoform from skeletal muscle. The negligible troponin T levels seen after high energy cardioversion indicate that significant myocardial injury does not occur. Electrical injury is not likely to account for the elevated troponin T levels seen after out-of-hospital resuscitation in patients without myocardial infarction.

Aged↗
PubMed1996

Chronic memory impairment after cardiac arrest outside hospital.

OBJECTIVES: To evaluate the nature, prevalence, and severity of chronic memory deficit in patients resuscitated after cardiac arrest outside hospital and to determine whether such deficits are related to duration of cardiac arrest. DESIGN: Case-control study. SUBJECTS: 35 survivors of cardiac arrest outside hospital and 35 controls matched for age and sex who had had acute myocardial infarction without cardiac arrest. MAIN OUTCOME MEASURES: Subjects assessed at least two months after index event for affective state (hospital anxiety and depression scale), premorbid intelligence (national adult reading test), short term recall (digit recall test), and episodic long term memory (Rivermead behavioural memory test). RESULTS: Cases and controls showed no difference in short term recall. Cases scored lower on Rivermead test than controls (mean (SD) score out of 24 points: 17.4 (5.4) v 21.8 (2.0), P < 0.001), particularly in subtests relating to verbal and spatial memory. Moderate or severe impairment was found in 37% of cases and in no controls. Severity of impairment of memory correlated significantly with measures of duration of cardiac arrest. This deficit was not significantly associated with subjects' age, interval from index event to assessment, occupation, measures of comorbidity, social deprivation, anxiety or depression scores, or estimated premorbid intelligence. CONCLUSIONS: Clinically important impairment of memory was common after cardiac arrest outside hospital. Improvement in response times of emergency services could reduce the severity of such deficits. With an increasing numbers of people expected to survive cardiac arrest outside hospital, rehabilitation of those with memory deficit merits specific attention.

Aged↗
PubMed1996

Resuscitation from out-of-hospital cardiac arrest: implications for cardiac enzyme estimation.

BACKGROUND: diagnosis of precipitating myocardial infarction is essential for management of victims of out-of-hospital cardiac arrest, since investigations and treatment are determined by the underlying cause. Skeletal muscle and myocardial damage from external cardiac massage and defibrillation may complicate biochemical diagnosis of myocardial infarction. OBJECTIVES: (a) to examine the relationship between cumulative defibrillation energy and serum levels of cardiac troponin T and MB creatine kinase (MB-CK) mass in out-of-hospital cardiac arrest survivors without electrocardiographic evidence of myocardial infarction; (b) to reassess diagnostic thresholds for myocardial infarction using MB-CK mass and troponin T in this setting. METHODS: 77 victims of out-of-hospital cardiac arrest were studied. Serum was obtained for MB-CK mass, CK and troponin T estimation on the first 4 days of admission. Patients were divided into three groups using electrocardiographic criteria: group 1, myocardial infarction; group 2, no evidence of infarction; and group 3, equivocal electrocardiograms. Correlation coefficients were calculated for highest recorded levels of the biochemical markers versus defibrillation energy. Receiver-operating characteristic plots were used to determine optimum biochemical diagnostic thresholds for subjects in groups 1 and 2. RESULTS: using predefined criteria, 27 patients had myocardial infarction, 34 did not have myocardial infarction and 16 had equivocal electrocardiograms. Significant correlations were found for defibrillation energy versus log troponin T (r = 0.42, P < 0.05), log MB-CK mass (r = 0.51, P < 0.01) and total CK (r = 0.68, P < 0.001) in group 2. Within groups 1 and 2, MB-CK mass and troponin T provided additional diagnostic value over MB-CK fraction (P < 0.001). Diagnostic accuracy was not improved by adjusting for shock energy. The optimum threshold value was 4 ng/ml for troponin T (sensitivity 88%, specificity 95%), 60 ng/ml for MB-CK mass (sensitivity 88%, specificity 88%) and 8% of total CK for MB-CK fraction (sensitivity 74%, specificity 82%). These values should be interpreted with caution, since this study is limited by the exclusion of patients with uncertain electrocardiographic diagnoses into group 3. CONCLUSIONS: skeletal muscle and myocardial damage occurs in survivors of out-of-hospital cardiac arrest and is related to the duration of resuscitation. This complicates biochemical diagnosis of underlying myocardial infarction. Specific high diagnostic threshold values for MB-CK and troponin T are needed to optimise diagnostic accuracy. The use of MB-CK fraction leads to greater diagnostic error because of the variability of muscle CK release after resuscitation.

Aged↗
PubMed1996

Latissimus dorsi muscle: assessment of stimulation after cardiomyoplasty with Doppler US tissue imaging.

PURPOSE: To evaluate Doppler ultrasound (US) tissue imaging for assessment of stimulated skeletal muscle contraction. MATERIALS AND METHODS: Seven patients were studied after left latissimus dorsi cardiomyoplasty. Myograft contraction programmed on alternate cardiac cycles was assessed with Doppler US tissue imaging. Beat-to-beat variation in inferior wall motion was assessed by examining peak myograft velocities during 10 muscle-assisted and 10 nonassisted cardiac cycles. The temporal relationship between electrostimulation and myograft contraction, changes in cardiac geometry, and the effect of alterations in stimulation voltage and muscle synchronization were assessed. RESULTS: Significant beat-to-beat variation in velocity profile could be detected in the proximal myograft in six patients (P < .05). Potentiation of infero-posterior wall motion was measurable in five patients (mean peak systolic wall velocity: nonassisted, 2.5 cm.sec-1 +/- 0.5 [standard deviation]; assisted, 7.8 cm.sec-1 +/- 6.3). The response between stimulation voltage and inferoposterior wall velocity was sigmoid. CONCLUSION: Doppler US tissue imaging depicted the effects of myostimulator programming on muscle contraction and ventricular wall motion.

Cardiomyoplasty↗
PubMed1995

In-hospital mortality after out-of-hospital cardiac arrest.

In-hospital management of out-of-hospital cardiac arrest is complicated by uncertainty about prognosis and the need to identify markers of adverse outcome in individuals surviving initial resuscitation. We sought to identify factors that predict in-hospital death among patients who initially survive out-of-hospital cardiac arrest. We investigated 346 consecutive cases of out-of-hospital cardiac arrest received by a single centre in Edinburgh, UK (270 cases examined retrospectively, 76 prospectively). Of the retrospective cohort, 246 cases were thought to be of cardiac origin. There were associations between in-hospital mortality and pre-arrest variables, resuscitation variables, and factors measured during admission. Crew-witnessed arrests were associated with low mortality; arrest rhythm (p < 0.001), resuscitation by a health professional (p < 0.05), conscious level on admission (p < 0.001), and requirement for ventilation (p < 0.05) independently predicted in-hospital mortality. A weighted prognostic scoring system based on three of these variables accurately predicted the likelihood of in-hospital death in the prospective test group. Further assessment of conscious level during admission with the Glasgow coma score predicted mortality rates in the study population, but coma did not predict a hopeless prognosis in individual cases unless it persisted for 72 h or more. Accurate prognostic assessment of out-of-hospital cardiac arrest survivors can be made from information available on admission. Of factors that independently predicted outcome, the skill of the resuscitator is most readily modified. This suggests that public training in resuscitation may reduce mortality rates.

Adult↗