Joseph J. Smolich

Postmenopausal Hormone Replacement Therapy Increases Coagulation Activity and Fibrinolysis

Hormone replacement therapy (HRT) appears to be cardioprotective in postmenopausal women; however, concerns exist over its thrombogenic effects. To address the effects of combined HRT on coagulation and fibrinolysis, we have measured circulating markers of these processes in a double-blind placebo-controlled trial. Forty-two healthy postmenopausal women aged 50 to 75 years received continuous combined HRT with 2 mg estradiol+1 mg norethisterone or placebo for 6 weeks. Hormone profiles were measured at baseline, and lipid and hemostatic parameters were measured at baseline and after 6 weeks of therapy. Baseline characteristics were similar in the 2 groups. With change from baseline the main outcome measure, HRT increased the markers of coagulation (prothrombin fragments 1+2, 0.20+/-0.06 versus 0.06+/-0.04 nmol/L, P=0.0005; soluble fibrin, 2.3+/-0.4 versus 0.25+/-0.3 microgram/mL, P=0.0004), reduced plasma fibrinolytic inhibitory activity (plasminogen activator inhibitor-1, -0.67+/-0.16 versus 0.24+/-0.21 U/mL, P=0.002), and increased fibrinolysis (D-dimer, 24+/-12 versus -6+/-8 ng/mL, P=0.04) compared with placebo. Increases in soluble fibrin and D-dimer were positively correlated (r=0.59, P=0.02), but changes in plasminogen activator inhibitor-1 and D-dimer were unrelated. Although baseline hemostatic and lipid parameters were correlated, there were no associations between changes in hemostatic markers and lipids after treatment. Short-term oral combined continuous HRT (estradiol and norethisterone) increased thrombin and fibrin generation, reduced plasma fibrinolytic inhibitory activity, and increased fibrinolysis. Enhanced fibrinolysis was related to increased fibrin generation but not reduced plasma fibrinolytic inhibitory activity. Coagulation activation may partly explain the increases in venous thrombosis and cardiovascular events reported with the use of combined HRT.

Determinants of Increased Regional Left Atrial Coagulation Activity in Patients With Mitral Stenosis

BACKGROUNDnRecent evidence suggests that regional left atrial coagulation activity may be increased in mitral stenosis and perhaps contribute to the pathophysiology of left atrial thrombus. However, the relation of left atrial coagulation activity to factors that predispose to left atrial thrombus formation is unknown, and the relation between left atrial and systemic coagulation activities is unresolved.nnnMETHODS AND RESULTSnLeft atrial and peripheral venous levels of the coagulation marker prothrombin fragment 1 + 2 (F1 + 2) were measured in 32 patients with mitral stenosis with normal clotting times and no left atrial thrombus who were undergoing percutaneous balloon mitral valvuloplasty. Baseline peripheral venous F1 + 2 levels, measured at the beginning of the valvuloplasty procedure, did not differ from those of 30 age-matched control patients. Prevalvuloplasty left atrial F1 + 2 levels, obtained immediately after transseptal puncture, were similar to femoral venous levels in patients without left atrial spontaneous echo contrast (LASEC) (0.81 +/- 0.32 versus 0.81 +/- 0.27 nmol/L, n = 7) but greater than femoral venous levels in patients with LASEC and either sinus rhythm (1.57 +/- 0.86 versus 0.99 +/- 0.38 nmol/L, n = 16, P < .001) or atrial fibrillation (1.52 +/- 0.69 versus 0.85 +/- 0.33 nmol/L, n = 9, P < .003). Furthermore, LASEC emerged as the only significant predictor of increased regional left atrial coagulation activity (P = .005) on stepwise multivariate logistic regression analysis.nnnCONCLUSIONSnIncreased regional left atrial coagulation activity in mitral stenosis occurs in the presence of LASEC, is evident in either sinus rhythm or atrial fibrillation, and is associated with normal systemic coagulation activity.

Neuronal reuptake of norepinephrine and production of dihydroxyphenylglycol by cardiac sympathetic nerves in the anesthetized dog.

BackgroundReuptake of norepinephrine by cardiac sympathetic nerves before and during two levels of electrical stimulation of the left ansa subclavia was estimated in anesthetized dogs from the cardiac production of dihydroxyphenylglycol (DHPG), the intraneuronal metabolite of norepinephrine. Methods and ResultsThe method depended on the effects of neuronal uptake blockade with desipramine on the cardiac production of [3H]DHPG from intravenously infused [3H]norepinephrine. The ratio of the desipramine-induced decrease in the cardiac extraction of [H]norepinephrine to the production of [3H]DHPG was used to transform the cardiac production of DHPG from recaptured norepinephrine into a rate for norepinephrine reuptake. Cardiac spillover of norepinephrine into plasma increased from 49 ± t12 to 205 ± 40 and 451 ± 118 pmol/min during sympathetic activation. Cardiac DHPG production increased from 108 ± 18 to 166 + 34 and 240 ± 47 pmol/min. Desipramine decreased resting cardiac DHPG production by 20%o and completely blocked the stimulation-induced increase. Thus, most (80%) cardiac DHPG produced at rest was derived from norepinephrine leaking from storage vesicles. This amount remained constant, and that derived from recaptured norepinephrine increased during sympathetic activation. The cardiac extraction of [3H]norepinephrine (126,000 dpm/min) and production of [3H]DHPG (3,790 dpm/min) were decreased by 55–57% after desipramine. Thus, only 3% of the norepinephrine recaptured by cardiac sympathetic nerves appeared in plasma as DHPG. The remainder was sequestered into storage vesicles (more than 94%) or ultimately formed metabolites other than DHPG (less than 3%e). Reuptake of norepinephrine by cardiac sympathetic nerves was 1,188 + 476 pmollmin and increased in parallel with cardiac norepinephrine spillover to 4,182 + 1,982 and 6,594 ± 2,241 pmollmin during sympathetic stimulation. ConclusionsOf the norepinephrine released by cardiac sympathetic nerves, 16-fold more was recaptured than entered plasma. Combined estimation of norepinephrne reuptake and spillover offers an approach to assess the efficiency of neuronal reuptake in disorders of cardiac function.

Effect of lung liquid volume on respiratory performance after caesarean delivery in the lamb.

1. The volume of liquid in the lungs of the fetal lamb is reported to fall in the final days of gestation and during labour itself. We aimed to test the hypothesis that this fall in liquid volume adapts the lungs for air breathing and pulmonary gas exchange. 2. In twelve chronically catheterized fetal lambs we measured lung liquid volume at 140 days gestation (term is 147 days) and then delivered the fetuses by Caesarean section under maternal spinal anaesthesia. In five fetuses we removed approximately half the liquid contained in the lungs just before delivery (experimental group) while the remaining seven fetuses were delivered without change to their lung liquid (control group). 3. Lambs born with reduced lung liquid volume improved their arterial blood gas and acid‐base status more quickly than lambs born without alteration to lung liquid. 4. Carotid arterial blood gas values in the first 60 min of postnatal life were significantly related to the volume of liquid present in the lungs at birth, with higher arterial partial pressure of oxygen (Pa,02) and arterial oxygen saturation (Sa,02) and lower arterial partial pressure of carbon dioxide (Pa,CO2) levels being associated with lower lung liquid volumes. 5. We conclude that postnatal gas exchange is enhanced by a reduction in the volume of liquid remaining in the lungs when breathing starts.

Relationship of waist and hip circumference with coagulation and fibrinolysis in postmenopausal women

The contribution of obesity to the occurrence of cardiovascular events may not be wholly related to its influence on traditional risk factors. Coagulation and fibrinolysis may also influence cardiovascular risk, but the relationship of adiposity with these processes is unclear. The aim of the present study was to investigate the relationships of BMI (body mass index), waist circumference, hip circumference and WHR (waist-to-hip ratio) with VIIc (factor VII activity), plasma markers of thrombin generation [F1+2 (prothrombin fragment 1+2)], fibrin formation [SF (soluble fibrin)] and fibrin turnover (D-dimer), and PAI-1 (plasminogen activator inhibitor-1; a marker of fibrinolytic inhibitory capacity). The study cohort was 80 healthy postmenopausal women who were not diabetic, current smokers or taking hormone therapy and who had a fasting sample of blood collected. VIIc, F1+2, SF and PAI-1 were all positively correlated with BMI, waist circumference and WHR, whereas D-dimer was positively correlated with waist circumference and WHR, but not BMI. WHR was the strongest correlate of all the markers except for PAI-1, which was most closely related to BMI. Hip circumference became a negative correlate of F1+2 and D-dimer after adjusting for waist circumference. The relationships of WHR with F1+2 and SF, but not with VIIc and D-dimer, were independent of traditional risk factors. The positive association between waist circumference and markers of thrombin generation, fibrin production and fibrin turnover suggests that abdominal adiposity may contribute to atherothrombosis by activating intravascular coagulation. In contrast, a larger hip circumference appears to have a protective affect against coagulation activation.

Increased systemic oxygen consumption offsets improved oxygen delivery during dobutamine infusion in newborn lambs

Abstract.Objective: To determine: 1) if dobutamine elicited a thermogenic response during postnatal development; and 2) if this response impacted on the balance between systemic O2 delivery (DO2) and O2 consumption (VO2), and involved one or a combination of adrenoceptor subtypes. Design: Prospective non-randomized unblinded study. Setting: University research laboratory. Subjects: Thirty-five Border-Leicester cross lambs used in a main study performed at 1–2xa0days (n=7), 7–10xa0days (n=7), and 6–8xa0weeks (n=8), and in a adrenoceptor blockade substudy performed at 1–2xa0days (n=13). Interventions: Lambs were instrumented under anaesthesia and dobutamine was infused at incremental rates of 1–40xa0µg/kg per minute. In separate subgroups of 1–2xa0day-old lambs, dobutamine was infused after selective or combined α1, β1, and β2-adrenoceptor blockade. Measurements: Cardiac output, aortic and pulmonary arterial blood gases, and body temperature were measured. DO2 and VO2 were calculated. Mainresults: Dobutamine increased DO2 similarly at all three ages. Dobutamine also increased VO2 in the absence of muscle shivering, but the average rise in 1–2xa0day-old lambs was sevenfold to 12-fold greater (P<0.001) than in 7–10xa0day-old and 6–8 week-old animals, was associated with an increase in systemic O2 extraction, and accounted for ≈90% of the rise in DO2. Body temperature rose by 1.3±0.5xa0°C in 1–2xa0day-old animals (P<0.001), but was unchanged in 7–10xa0day-old or 6–8 week-old lambs. In 1–2xa0day-old lambs, rises in DO2, VO2, and body temperature induced by dobutamine were not affected by selective α1, β1 or β2 adrenoceptor blockade, but were markedly attenuated by combined adrenoceptor blockade. Conclusions: A substantial rise in VO2 which accompanied a pronounced thermogenic effect of dobutamine in newborn lambs utilized most of the associated increase in DO2 and appeared to be dependent on activation of multiple adrenoceptor subtypes.

Massive decline in lung liquid before vaginal delivery at term in the fetal lamb

OBJECTIVEnOur aim was to determine the volume of liquid remaining in the lungs of the fetal lamb just before a normal vaginal delivery at term to assess the extent to which an excess of liquid in the airspaces might contribute to the respiratory morbidity that accompanies elective cesarean delivery.nnnSTUDY DESIGNnThe volume of liquid in the future airspace of the lungs was determined at the end of labor in eight fetal lambs at term from the dilution of an impermeable tracer (125I-labeled human serum albumin) mixed into the liquid. This volume was compared with that measured in a second group of 10 fetal lambs studied 7 days before the expected date of delivery (term = 147 days).nnnRESULTSnThe volume of lung liquid present at the end of labor was 6.8 +/- 1.0 ml x kg(-1) (n = 8) compared with 28.2 +/- 1.8 ml x kg(-1) (n = 10) in the second group of lambs studied before the onset of labor at 140 days of gestation.nnnCONCLUSIONnOur results indicate that the bulk (>75%) of the liquid that fills the lungs of the fetal lamb at 140 days of gestation is cleared at some time before normal term birth, suggesting that the adverse respiratory impact of elective cesarean delivery may be largely explained by denying the fetus this important adaptive mechanism.

Indirect relation between rises in oxygen consumption and left ventricular output at birth in lambs.

To examine the relation between increased newborn oxygen requirements and the postnatal rise in cardiac output, we measured left ventricular (LV) output, organ blood flows, and whole-body oxygen consumption using radioactive microspheres in late-gestation sheep fetuses and in the same animals 1 and 4 hours after cesarean section delivery. LV output rose from 264 +/- 23 ml.min-1.kg body wt-1 in fetuses to 444 +/- 33 ml.min-1.kg body wt-1 in lambs at 1 hour after delivery (p less than 0.005) and was unchanged at 4 hours after delivery. This rise in LV output was associated with a more than fourfold increase in the LV flow contribution to tissues situated distal to the ductus arteriosus (fetus, 51 +/- 9 ml.min-1.kg body wt-1; lamb, 226 +/- 22 ml.min-1.kg body wt-1; p less than 0.005), which were mainly perfused by the right ventricle in utero. However, average blood flow to body tissues was similar in fetuses (37 +/- 4 ml.min-1.100 g tissue-1), 1-hour lambs (39 +/- 4 ml.min-1.100 g tissue-1), and 4-hour lambs (40 +/- 5 ml.min-1.100 g tissue-1). Oxygen consumption increased by 58%, from 7.84 +/- 0.43 ml.min-1.kg body wt-1 in fetuses to 12.38 +/- 2.4 ml.min-1.kg body wt-1 in 1-hour lambs (p less than 0.01), and was unchanged in 4-hour lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of combined oral hormone replacement therapy on tissue factor pathway inhibitor and factor VII.

Oral combined hormone replacement therapy (HRT) with oestradiol and norethisterone increases plasma levels of prothrombin fragment 1+2 (F1+2), indicating an increase in thrombin generation, but the mechanisms underlying this increase are uncertain. The aim of this randomized, placebo-controlled study was to determine whether an increase in factor VII, a factor that combines with tissue factor to activate the extrinsic pathway, or a decrease in tissue factor pathway inhibitor (TFPI), an inhibitor of extrinsic pathway activation, may contribute to increases in thrombin generation occurring with HRT. Healthy postmenopausal women aged 50-75 years received placebo (n=19) or oral combined HRT (n=18) and had blood collected for measurement of factor VII coagulation activity (VIIc), activated factor VII (VIIa) and TFPI at baseline and at 6 weeks. Baseline characteristics were similar in the two groups, including age, body mass index and cholesterol levels. As reported previously, HRT increased the F1+2 concentration by 20%. Placebo had no effect on VIIc, VIIa or TFPI, but 6 weeks of combined HRT decreased VIIc [from 1.11+/-0.06 (mean+/-S.E.M.) to 1.03+/-0.06 i.u./ml; P<0.03], VIIa [from 43.9; 10.8-198.3 (median; range) to 35.0; 6.3-66.8 m-units/ml; P<0.03] and TFPI [from 81.3+/-6.5 to 60.4+/-5.5 ng/ml; P<0.0001]. The decrease in TPFI with HRT was not correlated with the elevation in F1+2 levels. In conclusion, the increase in thrombin generation seen with HRT is not due to an effect on factor VII; in addition, while a contribution from the decrease in TFPI is possible, increased thrombin generation is not directly related to the decrease in TFPI.

Haematologic determinants of left atrial spontaneous echo contrast in mitral stenosis

OBJECTIVESnTo determine if a relationship exists in mitral stenosis, in patients with either sinus rhythm or atrial fibrillation, between left atrial spontaneous echo contrast and the haematologic indices haematocrit, red cell concentration, mean corpuscular volume, platelet count and volume.nnnMETHODSnLeft atrial spontaneous echo contrast severity was graded on a scale of 0-4 in 163 patients with symptomatic mitral stenosis (84 patients in sinus rhythm, 79 patients in atrial fibrillation) undergoing transesophageal echocardiography, cardiac catheterization and full blood examination as part of assessment prior to balloon mitral valvuloplasty.nnnRESULTSnIn sinus rhythm, spontaneous echo contrast grade was negatively correlated with cardiac index (r=-0.33), mitral valve area (r=-0.25) and mitral regurgitation grade (r=-0.22) and positively correlated with haematocrit (r=0.24) and red cell concentration (r=0.25). Spontaneous echo contrast grade was not correlated with left atrial diameter or mean corpuscular volume. In atrial fibrillation, spontaneous echo contrast grade was also negatively correlated with mitral valve area (r=-0.25) and mitral regurgitation (r=-0.36) but was positively correlated with left atrial diameter (r=0.34) and was not correlated with cardiac index, haematocrit or red cell concentration. There was no correlation between spontaneous echo contrast grade and platelet variables in either group.nnnCONCLUSIONSnNatural variation in red cell concentration in patients with symptomatic mitral stenosis was an independent predictor of the severity of left atrial spontaneous echo contrast in sinus rhythm, but no relationship between red cell concentration and spontaneous echo contrast grade was evident in atrial fibrillation.