Left atrioventricular plane displacement but not left ventricular ejection fraction is influenced by the degree of aortic stenosis.

AIMS: To examine how left atrioventricular plane displacement (AVPD), a widely used measure of left ventricular (LV) function, is related to presence and degree of aortic stenosis. METHODS AND RESULTS: Cardiac dimensions, LV filling, left AVPD, LV ejection fraction (LVEF), and valve function were assessed by echocardiography/Doppler in 182 patients with various cardiac diseases (mean (SD) age 69 (12) years, 36% women), 49 consecutive with and 133 consecutive without aortic stenosis. In an analysis of covariance, neither left AVPD nor LVEF was independently correlated with the presence of aortic stenosis. However, looking separately at patients with aortic stenosis, left AVPD (p = 0.03) but not LVEF correlated independently with degree of aortic stenosis in multiple linear regression analysis. In patients with aortic stenosis, an abnormal left AVPD had 94% sensitivity and 90% negative predictive value with regard to severe aortic stenosis, compared with 56% and 62%, respectively, for LVEF. CONCLUSION: In patients with cardiac disease, neither left AVPD nor LVEF correlated independently with presence of aortic stenosis. However, in patients with aortic stenosis, left AVPD but not LVEF correlated with the degree of aortic valve obstruction and left AVPD but not LVEF had high sensitivity and negative predictive value with regard to severe aortic stenosis. Compared with LVEF, left AVPD is an earlier and more sensitive marker of LV haemodynamic load in patients with aortic stenosis.

Left atrioventricular plane displacement determined by echocardiography: a clinically useful, independent predictor of mortality in patients with stable coronary artery disease.

BACKGROUND: Echocardiographically determined left atrioventricular plane displacement (AVPD) is strongly related to prognosis in patients with chronic heart failure and in postmyocardial infarction patients. We aimed at exploring whether AVPD, unlike ejection fraction, is related to mortality in patients with stable coronary artery disease (CAD). METHODS AND RESULTS: Atrioventricular plane displacement was assessed by two dimensionally guided M-mode echocardiography in the four and two chamber views, in 333 consecutive patients with stable CAD and an abnormal coronary angiogram. Patients were followed up for an average of 41 months. AVPD was lower in patients who died (n= 30, 9.0 %) compared with survivors (9.0 +/- 2.2 vs. 11.5 +/- 2.1 mm, P<0.0001). Amongst patients with prior myocardial infarction (n=184) AVPD was 8.7 +/- 2.3 mm in those who died (n=17) and 11.2 +/- 2.3 mm in the survivors (P<0.0001). In patients without prior myocardial infarction (n=149), AVPD was 9.4 +/- 2.1 (n=13) and 11.8 +/- 1.8 mm, respectively (P<0.0001). Age, AVPD and four other echocardiographical variables correlated significantly with prognosis in univariate logistic regression analysis. In multiple logistic regression analysis only AVPD (P<0.0001) correlated independently with mortality. CONCLUSION: Echocardiographically determined AVPDis a clinically useful, independent prognostic tool in patients with stable CAD. The presence of a documented previous myocardial infarction does not influence this observation.

Echocardiographic assessment of left atrioventricular plane displacement as a complement to left ventricular regional wall motion evaluation in the detection of myocardial dysfunction.

AIM: We aimed to find out if abnormal left atrioventricular plane displacement (AVPD) is a sign of myocardial dysfunction, even in patients with normal left ventricular (LV) regional wall motion (RWM). METHODS: We prospectively performed echocardiography in 1350 consecutive patients referred to our echocardiography laboratory. Left AVPD and LV RWM were evaluated in all patients. We prospectively selected all patients with normal LV RWM but impaired left AVPD for further analysis of clinical parameters. RESULTS: Eighty-eight of the 1350 patients had completely normal LV RWM but impaired left AVPD (< or = 10 mm) in at least one region (septal, lateral, posterior, anterior). Of these, 60.2% had prior and/ or acute myocardial infarction, predominantly non-Q-wave, whereas 33.0% had angina without infarction and 2.3% had hypertension. In 49 (55.7%) patients coronary angiography was performed. All were abnormal. In 4.5% (n = 4) of the patients no obvious reason for the AVPD decrease was found, but was not precluded. CONCLUSION: Almost all patients with abnormal left AVPD and completely normal LV RWM had clinical cardiac disease. Thus, decreased AVPD despite normal LV RWM seems to be a true sign of myocardial dysfunction, predominantly indicating subendocardial dysfunction. In screening for patients with myocardial dysfunction assessment of left AVPD may be useful as a complement to LV RWM evaluation. The prognosis in such patients is currently being evaluated.

Left ventricular diastolic filling is related to the atrioventricular plane displacement in patients with coronary artery disease.

OBJECTIVE: Left atrioventricular plane displacement (AVPD) is often decreased and abnormalities in left ventricular diastolic filling are common in patients with coronary artery disease (CAD). This study was designed to assess the relationship between AVPD and diastolic filling in patients with CAD. DESIGN: AVPD was assessed by echocardiography and diastolic filling by transmitral and pulmonary venous pulsed Doppler in 170 consecutive patients (66 +/- 11 years) with proven CAD at coronary angiography. Diastolic filling was grouped as normal, mildly impaired and moderately to severely impaired. RESULTS: A simple linear regression analysis showed that AVPD decreased in relation to increased severity of diastolic filling impairment (r = -0.36, p < 0.0001). In a multiple regression analysis, ejection fraction, diastolic filling, age and body surface were independently correlated with AVPD. Each millimetre of decrease in AVPD increased the probability of impaired diastolic filling by 28%. CONCLUSION: AVPD was independently correlated with both left ventricular systolic function and diastolic filling in patients with CAD. Thus, given the same degree of ejection fraction, it was found that the greater the impairment in diastolic filling, the lower the AVPD.

Effects on quality of life, symptoms and daily activity 6 months after termination of an exercise training programme in heart failure patients.

BACKGROUND: Exercise training in heart failure patients improves exercise capacity, physical function, and quality-of-life. Prior studies indicate a rapid loss of these effects following termination of the training. We wanted to assess any sustained post-training effects on patients global assessment of change in quality-of-life (PGACQoL) and physical function. METHODS: Fifty-four stable heart failure patients were randomised to exercise or control. The 4-month exercise programme consisted of bicycle training at 80% of maximal intensity three times/week, and 49 patients completed the active study period. At 10 months (6 months post training) 37 patients were assessed regarding PGACQoL, habitual physical activity, and dyspnea-fatigue-index. RESULTS: Both post-training patients (n=17) and controls (n=20) deteriorated PGACQoL during the 6-month extended follow-up, although insignificantly. However, post-training patients improved PGACQoL slightly but significantly from baseline to 10 months (P=0.006), differing significantly (P=0.023) from controls who were unchanged. Regarding dyspnea-fatigue-index, post-training patients were largely unchanged and controls deteriorated insignificantly, during the extended follow-up as well as from baseline to 10 months. Both groups decreased physical activity insignificantly during the extended follow-up, and from baseline to 10 months post-training patients tended to decrease whereas controls significantly (P=0.007) decreased physical activity. CONCLUSION: There was no important sustained benefit 6 months after termination of an exercise training programme in heart failure patients. A small, probably clinically insignificant sustained improvement in PGACQoL was seen in post-training patients. Controls significantly decreased the habitual physical activity over 10 months and post-training patients showed a similar trend. Exercise training obviously has to be continuing to result in sustained benefit.

Subsite mapping of the human pancreatic alpha-amylase active site through structural, kinetic, and mutagenesis techniques.

We report a multifaceted study of the active site region of human pancreatic alpha-amylase. Through a series of novel kinetic analyses using malto-oligosaccharides and malto-oligosaccharyl fluorides, an overall cleavage action pattern for this enzyme has been developed. The preferred binding/cleavage mode occurs when a maltose residue serves as the leaving group (aglycone sites +1 and +2) and there are three sugars in the glycon (-1, -2, -3) sites. Overall it appears that five binding subsites span the active site, although an additional glycon subsite appears to be a significant factor in the binding of longer substrates. Kinetic parameters for the cleavage of substrates modified at the 2 and 4' ' positions also highlight the importance of these hydroxyl groups for catalysis and identify the rate-determining step. Further kinetic and structural studies pinpoint Asp197 as being the likely nucleophile in catalysis, with substitution of this residue leading to an approximately 10(6)-fold drop in catalytic activity. Structural studies show that the original pseudo-tetrasaccharide structure of acarbose is modified upon binding, presumably through a series of hydrolysis and transglycosylation reactions. The end result is a pseudo-pentasaccharide moiety that spans the active site region with its N-linked "glycosidic" bond positioned at the normal site of cleavage. Interestingly, the side chains of Glu233 and Asp300, along with a water molecule, are aligned about the inhibitor N-linked glycosidic bond in a manner suggesting that these might act individually or collectively in the role of acid/base catalyst in the reaction mechanism. Indeed, kinetic analyses show that substitution of the side chains of either Glu233 or Asp300 leads to as much as a approximately 10(3)-fold decrease in catalytic activity. Structural analyses of the Asp300Asn variant of human pancreatic alpha-amylase and its complex with acarbose clearly demonstrate the importance of Asp300 to the mode of inhibitor binding.

ACE inhibition with ramipril improves left ventricular function at rest and post exercise in patients with stable ischaemic heart disease and preserved left ventricular systolic function.

AIMS: To assess the effects of 6 months intervention with +ramipril on resting and post exercise left ventricular function in patients with stable ischaemic heart disease and preserved left ventricular systolic function. METHODS AND RESULTS: Patients (n=98, age 65+/-9 years, 37% women) were randomized to double-blind treatment with ramipril 5 mg. day(-1)(n=32), ramipril 1.25 mg. day(-1)(n=34), or placebo (n=32). Resting and post maximum exercise echocardiography/Doppler examinations were performed at baseline and after 6 months. Changes over 6 months in resting transmitral E-wave deceleration time (Edt) and Edt adjusted for heart rate (Edt/RR) differed between the ramipril 5 mg, ramipril 1.25 mg, and placebo groups: Edt 24+/-82, -1+/-69, and -29+/-64 ms, respectively, P=0. 012; Edt/RR 30+/-105, 2+/-61, and -28+/-69 ms, respectively, P=0.015. Changes in the difference between resting and post exercise Edt/RR also varied between groups: -53+/-137, -28+/-118, and 35+/-101 ms, respectively, P=0.029. No differences in E/A indices were noted. Resting atrioventricular plane displacement improved in the combined ramipril groups vs the placebo group: 0.2+/-0.8 vs -0.2+/-1.3 mm, P<0.05.Conclusion Six months ramipril treatment in patients with stable ischaemic heart disease and preserved left ventricular systolic function improved resting left ventricular function and reduced the exercise induced diastolic filling abnormalities usually seen in these patients.

Left atrioventricular plane displacement at rest is reduced in relation to severity of coronary artery disease irrespective of prior myocardial infarction.

OBJECTIVE: To examine whether left atrioventricular plane displacement (AVPD) at rest was related to severity of coronary atherosclerosis. DESIGN AND PATIENTS: Global and regional left AVPD was evaluated by echocardiography in 159 consecutive patients with significant stenoses at coronary angiography and in 15 age-matched healthy controls. The setting was the University hospital with a primary catchment area of 250,000 inhabitants. RESULTS: Mean AVPD in controls, patients with one-, two-, and three-vessel disease was 13.5+/-1.1, 12.4+/-1.5, 11.3+/-2.2 and 10.9+/-2.1 mm, respectively (P<0.0001). Similar significant differences were found both in those with (n=69) and without (n=90) a diagnosis of prior myocardial infarction. Regional AVPD did not correspond to the localization of infarction or coronary atherosclerosis. CONCLUSION: Irrespective of a diagnosis of prior myocardial infarction, left AVPD was related to the degree and extent of coronary artery disease. It was significantly decreased compared to controls in patients with one-vessel disease, and was further decreased with increasing extent of coronary atherosclerosis. Determination of regional left AVPD could not be used to identify regions perfused by stenotic coronary arteries or regions affected by prior myocardial infarction.

Left atrioventricular plane displacement is related to both systolic and diastolic left ventricular performance in patients with chronic heart failure.

AIMS: Left atrioventricular plane displacement is proposed to reflect left ventricular systolic function and is strongly related to prognosis in patients with heart failure. Left atrioventricular plane displacement is a different measure of left ventricular function compared to ejection fraction, and the factors influencing left atrioventricular plane displacement are insufficiently characterized. We wanted to assess any relationship between left atrioventricular plane displacement and left ventricular diastolic performance. METHODS AND RESULTS: Left ventricular diastolic filling, left atrioventricular plane displacement, and fractional shortening were assessed by echocardiography/Doppler in 54 patients with chronic heart failure (age 64 +/- 7 years). Left atrioventricular plane displacement correlated significantly with Doppler variables of left ventricular filling, in particular the inverse logarithm of early transmitral flow deceleration time; log-1 Edt (r = -0.61, P < 0.0001, n = 54). Left atrioventricular plane displacement also correlated with fractional shortening (r = 0.49, P < 0.001, n = 50). However, fractional shortening did not correlate with any Doppler variable. Log-1 Edt, fractional shortening, age, heart rate, left ventricular and atrial size, and degree of mitral regurgitation were included in a multiple regression analysis. Only log-1 Edt (P = 0.001) and fractional shortening (P = 0.03) correlated independently with left atrioventricular plane displacement. Among patients with similar fractional shortening, those with more compromised diastolic performance had lower left atrioventricular plane displacement. CONCLUSION: Left atrioventricular plane displacement was related to both systolic and diastolic left ventricular performance, which may explain some of the discrepancies between left atrioventricular plane displacement and ejection fraction.

Low-molecular-weight heparin in preventing and treating DVT.

Low-molecular-weight heparin is a relatively recent addition to the list of therapies for prophylaxis and treatment of deep venous thrombosis (DVT). As a prophylactic, low-molecular-weight heparin is as effective as standard heparin or warfarin and does not require monitoring of the activated partial thromboplastin time or the International Normalized Ratio. Traditionally, treatment for DVT required patients to be hospitalized for administration of intravenous heparin. With subcutaneous injections of low-molecular-weight heparin, treatment of DVT can be initiated or completed in the outpatient setting with no increased risk of recurrent thromboembolism or bleeding complications. Low-molecular-weight heparin is an attractive option for use in patients with a first episode of DVT, no risk factors for bleeding and the ability to administer injections with or without the help of a visiting nurse or family member.

Cloning, mutagenesis, and structural analysis of human pancreatic alpha-amylase expressed in Pichia pastoris.

Human pancreatic alpha-amylase (HPA) was expressed in the methylotrophic yeast Pichia pastoris and two mutants (D197A and D197N) of a completely conserved active site carboxylic acid were generated. All recombinant proteins were shown by electrospray ionization mass spectrometry (ESI-MS) to be glycosylated and the site of attachment was shown to be Asn461 by peptide mapping in conjunction with ESI-MS. Treatment of these proteins with endoglycosidase F demonstrated that they contained a single N-linked oligosaccharide and yielded a protein product with a single N-acetyl glucosamine (GlcNAc), which could be crystallized. Solution of the crystal structure to a resolution of 2.0 A confirmed the location of the glycosyl group as Asn461 and showed that the recombinant protein had essentially the same conformation as the native enzyme. The kinetic parameters of the glycosylated and deglycosylated wild-type proteins were the same while the k(cat)/Km values for D197A and D197N were 10(6)-10(7) times lower than the wild-type enzyme. The decreased k(cat)/Km values for the mutants confirm that D197 plays a crucial role in the hydrolytic activity of HPA, presumably as the catalytic nucleophile.

Exercise training in heart failure improves quality of life and exercise capacity.

AIMS: Benefit from exercise training in heart failure has mainly been shown in men with ischaemic disease. We aimed to examine the effects of exercise training in heart failure patients < or = 75 years old of both sexes and with various aetiology. METHODS AND RESULTS: Fifty-four patients with stable mild-to-moderate heart failure were randomized to exercise or control, and 49 completed the study (49% > or = 65 years; 29% women; 24% non-ischaemic aetiology; training, n = 22; controls, n = 27). The exercise programme consisted of bicycle training at 80% of maximal intensity over a period of 4 months. Improvements vs controls were found regarding maximal exercise capacity (6 +/- 12 vs -4 +/- 12% [mean +/- SD], P < 0.01) and global quality-of-life (2 [1] vs 0 [1] units [median ¿inter-quartile range¿], P < 0.01), but not regarding maximal oxygen consumption or the dyspnoea-fatigue index. All of these four variables significantly improved in men with ischaemic aetiology compared with controls (n = 11). However, none of these variables improved in women with ischaemic aetiology (n = 5), or in patients with non-ischaemic aetiology (n = 6). The training response was independent of age, left ventricular systolic function, and maximal oxygen consumption. No training-related adverse effects were reported. CONCLUSION: Supervised exercise training was safe and beneficial in heart failure patients < or = 75 years, especially in men with ischaemic aetiology. The effects of exercise training in women and patients with non-ischaemic aetiology should be further examined.

Prognostic significance of changes in left ventricular systolic function in elderly patients with congestive heart failure.

BACKGROUND AND DESIGN: The prognostic significance of changes in left ventricular systolic function over time is unknown in elderly patients with heart failure. We prospectively examined the relation between 1-year changes in left ventricular systolic function by echocardiographic determination of atrioventricular plane displacement (AVPD), and subsequent 2-year mortality and morbidity in elderly patients with heart failure. AVPD determination allows for left ventricular function to be adequately assessed even when image quality is poor, as is common in the elderly. METHODS: AVPD was measured at baseline and 1 year in 123 patients with heart failure (age 76.0 +/- 5.4 years). An AVPD change of 1 mm or more (corresponding to an ejection fraction change of 0.05) was considered significant. RESULTS: AVPD decreased in 26 patients (21%), increased in 46 (37%), and was unchanged in 51 (42%). During a 2-year follow-up (from the 1-year examination) mortality, total hospitalizations, and hospitalizations for heart failure (35% of all hospitalizations) did not differ significantly between the three groups. Patients (n = 80) with AVPD of 8.2 mm or less (corresponding to left ventricular ejection fraction of 0.40 or less) at the 1-year examination demonstrated a higher mortality than patients with AVPD greater than 8.2 mm (43.8 versus 23.3%; P = 0.031), and also had more hospitalizations and days in hospital due to heart failure (1.0 +/- 1.5 versus 0.4 +/- 0.8, P = 0.020 and 10.4 +/- 15.6 versus 4.6 +/- 10.6, P = 0.033, respectively). CONCLUSIONS: Left ventricular function was readily assessed in all patients by determination of AVPD. Our results indicate that single but not serial assessment of left ventricular systolic function by determination of AVPD is of value in assessing the prognosis in elderly patients with heart failure.

Detection of intracellular calcium elevations in Xenopus laevis oocytes: aequorin luminescence versus electrophysiology.

Detection of receptor expression in Xenopus oocytes often relies upon functional coupling to second messengers such as Ca2+ or cyclic adenosine monophosphate. To detect intracellular Ca2+, electrophysiological measurement of the endogenous Ca(2+)-activated chloride current (ICl(Ca)) is often used (Dascal, 1987). An alternative utilizes the Ca2+ sensing, bioluminescent protein aequorin (Parker and Miledi(1986) Proc. R. Soc. Lond. B, 228: 307-315; Giladi and Spindel (1991) BioTechniques, 10: 744-747). In the present study the sensitivities of aequorin and electrophysiology for detecting receptor-mediated Ca2+ transients were compared. Assays were performed on the same batches of oocytes using either animal serum or ligands of exogenous receptors to generate inositol 1,4,5-trisphosphate (InsP3) and ultimately elevate intracellular Ca2+. Signal amplitudes were controlled by titrating the concentration of animal serum, or titrating the amount of receptor mRNA injected. Both assays detected signals with high concentrations of animal serum, or with high receptor density. However, aequorin signals were not detected in experiments with average ICl(Ca) current amplitudes below 200 nA. To further evaluate the differences between these two techniques, membrane current and bioluminescence were measured simultaneously. Results of these studies suggest that the signals differ due to the spatial distribution of aequorin, the chloride channels, and the calcium release sites.