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Biomedical subjects

G Y Lip

Publications and source records attributed to G Y Lip.

At least 19 recordsLinked to original sources
PubMed1999

Indexes of hypercoagulability measured in peripheral blood reflect levels in intracardiac blood in patients with atrial fibrillation secondary to mitral stenosis.

Systemic thromboembolism is a major complication in patients with mitral stenosis, especially in those who have atrial fibrillation (AF). It has been suggested that there may be increased regional left atrial coagulation activity in such patients, despite normal systemic coagulation activity on peripheral blood sampling. Our aim was to investigate whether there were significant differences between intracardiac versus peripheral indexes of hypercoagulability in 25 patients (5 men; mean age 60 years) with mitral stenosis who were undergoing percutaneous balloon mitral valvuloplasty and who were all in chronic AF. Two days after halting warfarin therapy, intracardiac (right and left atria) and peripheral (venous and arterial) blood samples from patients were obtained and compared with levels in matched healthy controls in sinus rhythm. Thrombogenicity was assessed by levels of fibrin D-dimer, fibrinogen, indexes of platelet activation (soluble P-selectin and beta thromboglobulin [betaTG]) and indexes of endothelial dysfunction (soluble thrombomodulin [sTM] and von Willebrand factor [vWF]). There were no statistically significant differences in the various markers between the femoral vein and artery, left and right atria, and between the femoral vein and both atria (all p = NS). Plasma fibrinogen, vWf (both p <0.005), and D-dimer (p = 0.011) were significantly higher and levels of sP-selectin and sTM were lower (both p <0.005) in patients when compared with controls. There was no significant difference in plasma betaTG levels. Our results suggest that there is no significant variation in indexes of thrombogenesis, platelet activation, and endothelial dysfunction between left atrium, right atrium, and the peripheral artery or vein. Peripheral samples therefore do reflect atrial coagulation, platelet, and endothelial activities.

Atrial Fibrillation↗
PubMed1999

Evaluation of the Sorin bicarbon bileaflet valve in 488 patients (519 prostheses).

The Sorin bicarbon bileaflet prosthesis was introduced in 1990. To evaluate the clinical performance of this prosthesis, we reviewed 519 prostheses that were implanted in 488 patients (275 men, 213 women; mean age 59 years; SD 10.8, range 19 to 88) from 1993 to 1997. Preoperatively, 82% of patients were in New York Heart Association (NYHA) functional class III or IV. There were 263 aortic valve replacements (AVRs) (54%), 194 mitral valve replacements (MVRs) (40%), and 31 AVRs and MVRs (both) (6%). Concomitant procedures were performed in 82 patients (17%). Follow-up was complete in 471 (97%) with a total cumulative follow-up of 866 patient-years. The 30-day mortality for patients with AVR was 5.7% (95% confidence interval [CI] 2.9 to 8.5), MVR 17.5% (CI 9.9 to 19.7), and both 19% (CI 7.6 to 51.1), with no early valve-related deaths. Patient survival at 55 months was 76% (SE 2.27%), with patients with AVR being 90%, MVR 63%, and both 61%. This was influenced by the following: (1) valve position, which was higher for MVR (p = 0.0001); (2) poor NYHA functional class (p = 0.0006); (3) reoperation (p = 0.02); and (4) age >70 years (p = 0.0001). Valve-related complications (expressed as percentage per patient year and number of events) were major thromboembolism at 0.9% per year (8), with AVR rates being 1.2% per year (6) and MVR 0.7% per year (2); major hemorrhage at 2.3% per year (20) with AVR rates being 2.4% per year (12) and MVR 2.5% per year (7); bacterial endocarditis at 0.2% per year (2); and nonstructural dysfunction rate of 0.7% per year (6). The reoperation rate was 0.9% per year (8) with AVR being 0.6% per year (3) and MVR 1.7% per year (5). At 55 months, actuarial freedom from major thromboembolism was 97% (SE 1.1%) with AVR being 96% and MVR 98%; major hemorrhage 89% (SE 3.1%) with AVR being 88.6% and MVR 91%; structural valve dysfunction 100% (SE 0.0%); and reoperation 97.1% (SE 1.10%) with AVR being 98.5% and MVR 94.6%. At follow-up, 88% of survivors were in NYHA class I or II. In this series, hospital mortality and overall survival in patients were influenced by the patients' clinical characteristics. There were no early valve-related deaths. Valve-related complications were similar to previously reported series with no episode of structural failure. Our experience with the Sorin bicarbon bileaflet prosthesis suggests that it has a satisfactory clinical performance, with low complication rates.

Adult↗
PubMed1999

Does heart failure confer a hypercoagulable state? Virchow's triad revisited.

It is well-recognized that patients with congestive heart failure are at an increased risk of stroke and venous thromboembolism. Nevertheless, stroke, thromboembolism and myocardial infarction have generally been regarded to be end points of secondary importance in large heart failure trials, when compared with mortality or hospital readmissions. It may well have been that the incidence of thrombotic events are underestimated. The problem of thrombus formation (thrombogenesis) in heart failure may therefore be a much more significant problem than is currently recognized. The pathophysiology of thrombogenesis in heart failure could well be explained in the context of Virchow's original triad. In addition to "abnormal flow" through low cardiac output, dilated cardiac chambers and poor contractility, patients with heart failure also demonstrate abnormalities of hemostasis and platelets (that is "abnormal blood constituents") and endothelial dysfunction ("vessel wall abnormalities"). These abnormalities contribute to a prothrombotic or hypercoagulable state, which increases the risk of thrombosis in heart failure and impaired left ventricular systolic function. Some observational data are available on the role of anticoagulants in heart failure, and there is sound evidence to support the use of antithrombotic therapy in patients with heart failure and atrial fibrillation. However, there are no large-scale prospective randomized controlled trials of antithrombotic therapy in patients with heart failure who remain in sinus rhythm, although important studies are in progress. Although the results of these studies are awaited, measurement of suitable markers of thrombogenesis might prove to be valuable in identifying "high risk" patients and in determining the nature, duration and intensity of such treatment. Further information is also needed on the predictive value of various markers of hypercoagulability in patients with heart failure, the association between hemostatic variables and the severity of heart failure, and the effects of different treatments.

Anticoagulants↗
PubMed1999

Atenolol and fetal growth in pregnancies complicated by hypertension.

Atenolol use may be associated with growth retardation when given in pregnancy, although the relationship to trimester of initiation, duration of treatment, and its use as monotherapy is still uncertain. To compare the obstetric and fetal outcome between women receiving atenolol (as monotherapy) and other antihypertensive drug monotherapies, and also to investigate the effect of duration of treatment on fetal growth, we performed a retrospective cohort study of 312 pregnancies in 223 women attending an Antenatal Hypertension Clinic. Atenolol (as monotherapy) was given in 78 pregnancies (25.0%), other types of antihypertensive drugs as monotherapy were given in 53 pregnancies (17.0%), and multiple drug combinations were given in 90 pregnancies (28.8%). In 91 pregnancies (29.2%) no antihypertensive drugs were given. Atenolol was found to be associated with lower birth weight and ponderal index values, with a trend toward a higher prevalence of preterm (<37 weeks) delivery and small-for-gestational-age babies when compared to other antihypertensive drugs as monotherapy, or to no treatment. The adverse effect of atenolol was more pronounced in women receiving the drug earlier in their pregnancy, and continuing the drug for a longer duration. In conclusion, atenolol should be avoided in the early stages of pregnancy and given with caution at the later stages, as it is associated with fetal growth retardation, which is related to duration of treatment.

Adult↗
PubMed1999

Comparison of primary coronary artery bypass surgery in a British Indo-Asian and white Caucasian population.

AIM: To compare the clinical characteristics, at the time of admission and after coronary revascularization by bypass surgery, among British patients of Indo-Asian and white Caucasian descent. METHOD: One hundred and ninety-four pairs of patients admitted between November 1994 and January 1997 were matched for age (within 3 years), sex and date of admission (within 3 months). Their clinical characteristics at the time of admission for coronary artery bypass grafting surgery, and the incidence of hospital morbidity, hospital mortality and length of stay in the intensive therapy unit or hospital following coronary artery bypass grafting were determined. RESULTS: A higher proportion of Indo-Asian patients underwent coronary revascularization on a non-elective basis (43% vs 32% white Caucasian patients, P =0.018), had a higher prevalence of diabetes (39% vs 12%, P =0.0001), a lower prevalence of smoking (36% vs 80%, P =0.0001) and a lower rate of previous myocardial infarction (47% vs 62%, P =0.012). As regards revascularization, although there was no significant difference in the number of vessels revascularized, there was a lower use of the arterial conduit (internal mammary artery) in the Indo-Asian patients (72% vs 81%, P =0.028) particularly for those undergoing emergency/urgent surgery (59% vs 72%, P =0.001) and with a previous myocardial infarction (65% vs 81%;P =0.01) when compared with their white Caucasian counterparts. Following surgery there were no differences in the types of support required for vital functions. There was no significant difference in the proportion of major post-operative complications, that is, haemorrhage, cerebrovascular accident, renal failure requiring dialysis or respiratory failure. Similarly, there were no differences in the length of intensive therapy unit stay (median stay 1 day vs 1 day, P =0.4) and hospital stay following surgery (median stay 6 days vs 6 days, P =0.5) between the two groups. Although there was a trend towards a higher in-hospital (30 day) mortality (6.7% [95% confidence intervals CI 3.18-10.21] vs 2.6% [CI 0.35-4.9;P =0.0618]), in Indo-Asians compared to white Caucasians this trend disappeared when patients in the two groups undergoing non-elective surgery only were compared (9% vs 7%;P =0.7). CONCLUSIONS: A higher proportion of Indo-Asians underwent non-elective coronary revascularization, with a significantly lower use of the arterial conduit and a relatively higher in-hospital mortality. Following coronary revascularization the medical management, length of stay and hospital morbidity in Indo-Asian patients was no different from that of their white Caucasian counterparts. This is despite a perceived poorer outcome in Indo-Asians compared to white Caucasians.

Asia↗
PubMed1999

The management of hypertensive disease in black patients.

The ethnic differences in the incidence, pathophysiology and management of hypertensive disease, are particularly pertinent to the Black or Afro-Caribbean populations, who have a high prevalence of hypertension and associated complications, such as strokes and renal impairment. Our understanding of the underlying pathophysiology of hypertensive disease and the optimal treatment of hypertension in Black patients continues to evolve, especially with the introduction of new drugs and the need for prognostic data in this ethnic population. We review the management of hypertensive disease in the black population, emphasizing race-related differences in the pathophysiology of hypertension and the importance of tailored management in this group of patients, including sensible application of non-pharmacological measures with effective antihypertensive agents. For example, diuretics and calcium antagonists are suitable first-line agents in black hypertensives, whilst beta-blockers and the ACE inhibitors tend to be less effective at lowering blood pressure, due to the low renin state in these patients.

Adrenergic alpha-Antagonists↗
PubMed1999

Atrial fibrillation, thromboembolism and antithrombotic therapy.

Atrial fibrillation is the commonest sustained disorder of cardiac rhythm and is associated with increased risk of stroke and thromboembolic events. Warfarin (dose-adjusted to a target INR of 2.0-3.0) has been well established to reduce this risk of stroke by 68% (95% CI 50-79%), while aspirin provides a risk reduction of 21% (95% CI 0-38%). Nevertheless, warfarin confers a risk of bleeding and the inconvenience of regular monitoring checks, while aspirin seems effective only for certain low-risk subgroups. Thus there have been strenuous efforts to improve thromboprophylaxis in atrial fibrillation, by using low-intensity anticoagulation regimens, combination antiplatelet therapy and refinement of risk stratification strategies. Attempts at using a low-intensity, fixed-dose warfarin regimen have, however, been disappointing. For now, a strategy of risk stratification should be adopted to identify highest risk patients with atrial fibrillation who would benefit from anticoagulation.

Aged↗
PubMed1998

Atrial fibrillation amongst the Indo-Asian general practice population. The West Birmingham Atrial Fibrillation Project.

Whilst there are recognised ethnic differences in cardiovascular disease, with a higher prevalence of hypertension and complications such as stroke amongst black/Afro-Caribbean populations, and ischaemic heart disease being more prevalent amongst Indo-Asians, the literature describing the clinical epidemiology of atrial fibrillation (AF) in non-caucasian groups is scarce. To survey the clinical features and management amongst Indo-Asian patients with known AF, we studied patients from six general practices in the west of Birmingham. The six general practices had a combined practice population of 25051, from which, the Indo-Asian population was 14670. A total of 12 Indo-Asian patients (six male, six female; mean age, 67 years; range, 42 to 95 years) with known AF were identified, suggesting a prevalence of AF in Indo-Asians aged >50 years of 0.6%. Six patients had chronic AF, two had recent onset (defined as onset <six months) and four had paroxysmal AF. Five patients had a history of ischaemic heart disease, three had hypertension, seven had heart failure, two had alcohol excess, four had mitral valve disease, and one patient with paroxysmal AF had sick sinus syndrome. None could be classified as having lone AF. Only four patients were anticoagulated, but, of the remaining eight, who were not taking warfarin, six were taking aspirin. None of the patients had contraindications to warfarin, but one of the patients who was taking aspirin had poor compliance to warfarin. In this survey of a general practice Indo-Asian population of approximately 14670, we found 12 patients with known AF. More information on the clinical epidemiology of AF in non-caucasian groups is still needed and urgently required, in view of the public health implications of this common cardiac arrhythmia.

Adult↗
PubMed1998

Endothelial integrity, soluble adhesion molecules and platelet markers in type 1 diabetes mellitus.

Recent developments in cell biology have identified new areas of direct relevance to the pathogenesis of Type 1 (insulin-dependent) diabetes mellitus and its complications. Endothelial damage is well recognized in diabetes--endothelial cell markers von Willebrand factor, soluble E-selectin, and soluble thrombomodulin are providing further evidence of the relationship between activation and damage to the vasculature and clinical disease in this condition. Cell surface bound adhesion molecules may also have a role in the development of atherosclerosis in patients with diabetes but the importance of the soluble forms of these molecules, such as intercellular adhesion molecule-1, is unclear. Evidence of platelet dysfunction has long been acknowledged in diabetes and new data are discussed. It is likely that a greater appreciation of the intimate interactions between endothelial integrity, adhesion molecules and platelets in Type 1 diabetes mellitus will provide a greater understanding of the risk of cardiovascular disease and stroke in patients with this disorder.

Arteriosclerosis↗