Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DECELERATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,711 records · Page 95Linked to original sources
PubMedDate not supplied

Doppler echocardiographic assessment of left ventricular diastolic function in myotonic dystrophy.

We utilized Doppler echocardiography to characterize left ventricular diastolic function in 42 patients with myotonic dystrophy (mean age 37 +/- 12 years, 64% male) who had no symptoms of heart failure and had normal left ventricular systolic function. Data were compared with those in 41 normal control subjects of similar age and gender. Heart rate, systemic blood pressure, and cardiac dimensions (wall thickness, left atrial and left ventricular cavity dimensions) were similar and not significantly different in patients and controls. As a group, patients showed significantly increased deceleration time and decreased rate of decline of flow velocity in early diastole (p < 0.0001 and p < 0.01, respectively) when compared to controls. Individual patient analysis showed that 10 (24%) of the 42 patients with myotonic dystrophy had 2 or more abnormal Doppler indexes of diastolic function consistent with a pattern of impaired left ventricular relaxation. The most common abnormalities were increased deceleration time (> 224 ms; 9 patients), prolonged isovolumic relaxation time (> 103 ms; 8 patients) and reduced rate of decline of flow velocity in early diastole (< 2.1 m/s2; 5 patients). In addition, peak early diastolic flow velocity was reduced (< 43 cm/s) in 3 patients and early to atrial peak flow velocity ratio was reduced (< 1) in 2 patients. Comparison of subgroups of patients with and without abnormal Doppler indexes showed no significant differences with regard to age, gender, heart rate, systemic blood pressure, severity of neuromuscular disease, and cardiac dimensions. After study, patients were clinically followed up for a mean period of 20 +/- 7 months (range 12-35). During observation no patients died and none experienced symptoms of heart failure. This Doppler echocardiographic analysis demonstrates that diastolic abnormalities may be present in patients with myotonic dystrophy, even in the absence of symptoms of cardiac failure or left ventricular systolic dysfunction. These diastolic abnormalities suggest an intrinsic myocardial abnormality in patients with myotonic dystrophy; however, whether they represent a preclinical phase of myocardial involvement or an intrinsic feature of the primary myocardial disease process in myotonic dystrophy remains to be elucidated.

Adolescent↗
PubMedDate not supplied

Influence of recombinant hirudin on tissue-factor-induced activation of coagulation in rabbits.

Uncontrolled activation of the tissue-factor (TF)-dependent extrinsic pathway of coagulation can lead to severe impairment of the hemostatic balance. AS thrombin plays the central role in the initiation of clotting, we used the highly specific thrombin inhibitor recombinant hirudin to prevent TF-induced coagulation activation in a rabbit model. Infusion of 0.5 micrograms.kg-1.h-1 TF in rabbits for 7 h led to a decrease in fibrinogen and platelets, to an increase in fibrin monomers and to a prolongation of TT, aPTT and PT. Recombinant hirudin was administered in doses of 0.5, 1 and 2 mg.kg-1 body weight (intravenous bolus), the protocol included a pre-TF (recombinant hirudin given at t = 0) and a post-TF study group (recombinant hirudin given at t = 2 h after the start of the TF infusion). Fibrinogen plasma levels, platelet counts and recombinant hirudin plasma levels were measured at baseline (t = 0) at 0.5, 1, 2, 3, 4, 5, 6, and 7 h; the deceleration rate of fibrinogen and platelets per hour was calculated for the control and the recombinant-hirudin-treated groups. The deceleration rate for fibrinogen in the TF group was -0.227 g.l-1.h-1 and was reduced by recombinant hirudin to -0.119, -0.116 and -0.095 g.1-1.h-1 for 0.5, 1 or 2 mg.kg-1, respectively (significant differences to control group, Jonckheere-Terpstra test). The inhibitor similarly prevented the decrease of platelets dose-dependently. Recombinant hirudin was cleared from plasma with a terminal half-life of about 100 min; however, even after its clearance from plasma, recombinant hirudin significantly prevented the fibrinogen and platelet drop. Recombinant hirudin was effective when given in the pre-TF as well as in the post-TF phase.

Animals↗
PubMed1979

Time factor in oxygen transfer from mother to fetus.

The time factor in the oxygen transfer from mother to fetus was studied by the tcPO2 technique. When a fairly constant fetal circulation made estimation possible, the decrease in fetal tcPO2 synchronous with and due to the uterine contractions in more than 400 events was always delayed 50--60 sec. Since the time lag in the increase in fetal tcPO2 following administration of pure oxygen to the mother was found to be of the same order of magnitude, the placental part of the delay in the oxygen transfer from mother to fetus can be assumed to be 50--60 sec. This determination supports the prevalent hypothesis that type II dips or late decelerations in the fetal heart rate are caused by hypoxia while type I dips or early decelerations are initiated by other factors.

Female↗
PubMed2003

Hysteresis effect implicates calcium cycling as a mechanism of repolarization alternans.

BACKGROUND: T-wave alternans is due to alternation of membrane repolarization at the cellular level and is a risk factor for sudden cardiac death. Recently, a hysteresis effect has been reported in patients whereby T-wave alternans, once induced by rapid heart rate, persists even when heart rate is subsequently slowed. We hypothesized that alternans hysteresis is an intrinsic property of cardiac myocytes, directly related to an underlying mechanism for repolarization alternans that involves intracellular calcium cycling. METHODS AND RESULTS: Stepwise pacing was used to induce alternans in Langendorff-perfused guinea pig hearts from which optical action potentials were recorded simultaneously at 256 ventricular sites with voltage-sensitive dyes and in whole-cell patch-clamped cardiac myocytes treated with or without BAPTA-AM (1,2-bis[2-aminophenoxy]ethane-N,N,N',N'-tetraacetic acid tetrakis [acetoxymethyl ester]). Alternans hysteresis was observed in every isolated heart: threshold heart rate for alternans was 280+/-12 bpm, but during subsequent deceleration of pacing, alternans persisted to significantly slower heart rates (238+/-5 bpm, P<0.05). Optical mapping showed that this effect also applied to the threshold for spatially discordant alternans (313+/-2.2 bpm during acceleration versus 250+/-6.6 bpm during deceleration, P<0.05). Alternans hysteresis was also observed in isolated cardiac myocytes. Moreover, calcium chelation by BAPTA-AM raised the threshold for alternans and inhibited hysteresis in a dose-dependent manner with no effect on baseline action potential duration. CONCLUSIONS: Alternans hysteresis is an intrinsic property of cardiac myocytes that can lead to persistence of arrhythmogenic discordant alternans even after heart rate is slowed. These results also support an important underlying role of calcium cycling in the mechanism of alternans.

Action Potentials↗
PubMed2004

Coronary blood flow assessment after successful angioplasty for acute myocardial infarction predicts the risk of long-term cardiac events.

BACKGROUND: Analysis of coronary flow velocity (CFV) in the recanalized infarct-related coronary artery (IRA) with a Doppler guidewire is useful for predicting recovery of regional left ventricular function, in-hospital complications, and survival. We postulated that the CFV pattern after IRA reperfusion for acute myocardial infarction (AMI) would predict long-term adverse cardiac events. METHODS AND RESULTS: Sixty-eight consecutive patients with a first AMI underwent CFV measurement with a Doppler guidewire after successful reopening of the IRA by coronary angioplasty. At the end of follow-up, 3.8+/-1.7 years after AMI, 44 of the 65 surviving patients (67.7%) were free of long-term cardiac events. Univariate analysis showed that the following factors were predictive of an end point combining cardiac death, recurrent MI, and congestive heart failure: hypertension, age > or =65 years, time from onset of chest pain to PTCA > or =6 hours, peak creatine kinase >4000 IU/L, ejection fraction < or =50%, proximal left anterior descending artery occlusion, resting average peak velocity < or =10 cm/s, average systolic peak velocity < or =5 cm/s, a rapid diastolic deceleration time (< or =600 ms), and early retrograde systolic flow. In the final multivariate model, only age > or =65 years (OR, 3.6; 95% CI, 1.1 to 11.8; P=0.03), time to PTCA > or =6 hours (OR, 2.9; 95% CI, 1.0 to 8.3; P=0.04), and a rapid diastolic deceleration time (OR, 5.4; 95% CI, 1.5 to 19.3; P=0.01) were independent predictors. CONCLUSIONS: The CFV pattern appears to be an accurate predictor of long-term cardiac events in patients having undergone successful reopening of the IRA after AMI, identifying a subset of at-risk patients.

Analysis of Variance↗
PubMed2000

Relation of phasic coronary flow velocity characteristics with TIMI perfusion grade and myocardial recovery after primary percutaneous transluminal coronary angioplasty and rescue stenting.

BACKGROUND: A residual stenosis and/or microvascular damage have been proposed as mechanisms of TIMI 2 flow for acute myocardial infarction. Coronary flow dynamics were assessed in patients with TIMI 2 flow to predict whether additional intervention would improve TIMI grade. METHODS AND RESULTS: In 35 patients who had a successfully recanalized anterior acute myocardial infarction using angioplasty or rescue stenting, coronary flow patterns were compared with corresponding TIMI grade and regional left ventricular wall motion (LVWM) 1 month after the intervention. After angioplasty, the time-averaged peak velocity (APV) was lower in patients with TIMI 2 flow (n=22) than in those with TIMI 3 flow (n=13; 7.9+/-3.9 versus 20.6+/-5.1 cm/s; P<0.001). Two different flow patterns were recorded in patients with TIMI 2 flow (versus TIMI 3, P<0.001); patients with type 1 TIMI 2 flow (n=15) had a reduced diastolic APV (8.3+/-4.8 versus 24.2+/-7.4 cm/s), prolonged diastolic deceleration time (1176+/-455 versus 728+/-205 ms), and a small diastolic/systolic APV ratio (1.3+/-0.6 versus 2.1+/-0.7); patients with type 2 TIMI 2 flow (n=7) had systolic flow reversal (systolic APV, -7.9+/-4.6 versus 11. 7+/-4.5 cm/s), a rapid diastolic deceleration time (221+/-84 versus 728+/-205 ms), and a negative diastolic/systolic APV ratio (-2.1+/-1. 4 versus 2.1+/-0.7). A significantly lower mean chord LVWM (-3.0+/-0. 2 versus -1.9+/-0.8; P<0.001) and a greater number of chords <-2SD (50+/-2 versus 28+/-18; P<0.001) were present in patients with type 2 versus type 1 TIMI 2 flow. Stenting increased TIMI 2 flow to TIMI 3 flow more in patients with type 1 than type 2 flow (67% versus 0%; P=0.003). Patients with TIMI 2 flow after stenting continued to demonstrate a type 2 pattern, and they had poor LVWM recovery. CONCLUSIONS: The differentiation between 2 types of TIMI 2 flow can predict the improvement of TIMI grade and LVWM recovery after additional stenting.

Aged↗
PubMed1989

Differentiation of constrictive pericarditis and restrictive cardiomyopathy by Doppler echocardiography.

Doppler ultrasound recordings of mitral, tricuspid, aortic, and pulmonary flow velocities, and their variation with respiration, were recorded in 12 patients with a restrictive cardiomyopathy and seven patients with constrictive pericarditis. Twenty healthy adults served as controls. The patients with constrictive pericarditis showed marked changes in left ventricular isovolumic relaxation time and in early mitral and tricuspid flow velocities at the onset of inspiration and expiration. These changes disappeared after pericardiectomy and were not seen in patients with restrictive cardiomyopathy or in normal subjects. The deceleration time of early mitral and tricuspid flow velocity was shorter than normal in both groups, indicating an early cessation of ventricular filling, but only patients with restrictive cardiomyopathy showed a further shortening of the tricuspid deceleration time with inspiration. Diastolic mitral and tricuspid regurgitation was also more common in the patients with restrictive cardiomyopathy. These results suggest that patients with constrictive pericarditis and restrictive cardiomyopathy can be differentiated by comparing respiratory changes in transvalvular flow velocities. In addition, although baseline hemodynamics in the two groups were similar, characteristic changes were seen with respiration that suggest differentiation of these disease states may also be possible from hemodynamic data.

Adult↗
PubMed1990

Restrictive diastolic abnormalities identified by Doppler echocardiography in patients with thalassemia major.

The consequences of transfusional iron overload on left ventricular diastolic filling have never been investigated systematically in patients with thalassemia major. In the present study, the pattern of left ventricular filling was assessed by Doppler echocardiography in 32 patients with thalassemia major (age, 17 +/- 5 years) who had not experienced symptoms of heart failure and had normal left ventricular systolic function. Data were compared with those obtained in 32 age-matched and sex-matched normal subjects. An abnormal Doppler pattern of left ventricular filling with increased flow velocity at mitral valve opening followed by an abrupt and premature decrease of flow velocity in early diastole was identified in the patients with thalassemia. Peak flow velocity in early diastole was increased in patients compared with controls (90 +/- 10 vs. 81 +/- 15 cm/sec; p less than 0.01), and rate of deceleration of flow velocity after the early diastolic peak and the ratio between the early and late (atrial) peaks of flow velocity were also increased (1,050 +/- 325 vs. 762 +/- 193 cm/sec2 and 2.7 +/- 0.7 vs. 2.2 +/- 0.5, respectively; p less than 0.001), whereas flow velocity deceleration time was reduced (97 +/- 22 vs. 119 +/- 19 msec; p less than 0.001). This Doppler pattern of diastolic filling is usually described as "restrictive" and reflects a decrease in left ventricular chamber compliance. A restrictive pattern of left ventricular filling was also identified in the subgroup of 16 study patients who had undergone optimal iron chelation therapy with deferoxamine.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Nonuniform course of left ventricular pressure fall and its regulation by load and contractile state.

BACKGROUND: Effects of systolic left ventricular pressure (LVP) on rates of pressure fall remain incompletely understood. This study analyzed phase-plane dP/dt versus LVP plots to differentiate between accelerating and decelerating effects and to investigate the variability in reported load effects on rates of LVP fall. METHODS AND RESULTS: Abrupt aortic occlusions were performed by inflating a balloon positioned in the ascending aorta of anesthetized open-chest dogs (n = 17). The occlusions resulted in clamp elevations of systolic LVP. In protocol A, the elevations of systolic LVP induced by total aortic occlusions were timed at early, mid, and late ejection. The magnitude of the elevations was 36.0 +/- 3.6 mm Hg for early, 11.6 +/- 0.6 mm Hg for mid, and negligible for late occlusions. The course of LVP fall appeared to be more complex than previously appreciated. Pressure fall might be subdivided in an initial accelerative phase, an intermediate decelerative phase, and a terminal decelerative phase. The initial phase accelerated with mid and late occlusions. The intermediate phase slowed down with early and to a lesser extent with mid occlusions. The terminal phase was never affected by aortic clamp occlusions. In protocol B, early elevations of systolic LVP were obtained with multiple graded aortic occlusions. The effects of matched LVP elevations of 12 mm Hg on rate of LVP fall were evaluated with the time constant of LVP fall (tau) and showed an interanimal variability ranging from acceleration and a 20% decrease in tau to deceleration and a 35% increase in tau. Changes in tau were moderately correlated with commonly used indexes of contractility (peak +dP/dt, r = -.78; regional fractional shortening, r = -.63). These changes in tau showed a close correlation with the systolic LVP of the test beat, expressed as a percentage of the peak isovolumetric LVP, obtained with total aortic occlusion (r = .984). This suggested that the contraction-relaxation coupling should be analyzed in terms of peak force development rather than contraction velocity or ejection fraction. CONCLUSIONS: LVP fall could be subdivided into an initial accelerative phase, an intermediate decelerative phase, and a terminal decelerative phase. Effects of elevations in systolic LVP on rate of LVP fall could be predicted by knowing peak isovolumetric LVP. Nonuniformity of LVP fall and adequate interpretation of load effects should be taken into account when clinical situations or pharmacological interventions are considered. In congestive heart failure, slow LVP fall could mainly reflect working conditions close to isovolumetric rather than relaxation disturbances.

Animals↗
PubMed1996

Alternation in the coronary blood flow velocity pattern in patients with no reflow and reperfused acute myocardial infarction.

BACKGROUND: Experimental and clinical evidence indicates that myocardial ischemia often damages the coronary microvasculature ("no-reflow" phenomenon). In this study, we examined the effect of this phenomenon on the coronary blood flow velocity pattern in patients with reperfused acute myocardial infarction. METHODS AND RESULTS: We measured coronary blood flow velocity after coronary angioplasty in 42 patients with acute myocardial infarction using a Doppler guidewire. Myocardial contrast echocardiography (MCE) was also performed before and after angioplasty. Thirty-one patients showed good contrast reperfusion (MCE reflow), whereas the other 11 showed no reflow (MCE no reflow). Peak velocity and duration of systolic coronary flow were significantly less in patients with MCE no reflow than in those with MCE reflow (8 +/- 4 versus 17 +/- 10 cm/s and 207 +/- 79 versus 289 +/- 55 ms, respectively; P < .01). Early systolic retrograde flow was frequently observed in patients with MCE no reflow, whereas it was observed in only 1 patient among those with MCE reflow (95% versus 3%; P < .001). Although peak diastolic flow velocity was similar between the two subsets, diastolic deceleration rate was significantly higher in patients with MCE no reflow than in those with MCE reflow (107 +/- 76 versus 56 +/- 31 cm/s2; P < .01). CONCLUSIONS: The coronary flow velocity pattern in patients with the no-reflow phenomenon was characterized by the appearance of systolic retrograde flow, diminished systolic antegrade flow, and rapid deceleration of diastolic flow. Thus, the Doppler guidewire allows us to assess the presence of microvascular dysfunction in AMI.

Aged↗
PubMed1997

Relaxation-systolic pressure relation. A load-independent assessment of left ventricular contractility.

This contribution reviews the regulation of left ventricular pressure (LVP) fall by load and relates this regulation to left ventricular contractility. Load regulation of LVP fall has to be distinguished from neurohumoral regulation, from effects induced by arterial reflected waves and from long-term load effects on contractility. The response of LVP fall to a moderate elevation of systolic LVP is highly variable. It depends on the ratio between the actual systolic pressure and peak isovolumetric pressure, defined as "relative load". Up to a relative load of 81% to 84%, LVP fall accelerates. Above this relative load, LVP fall decelerates. Depending on the level of relative load there is a wide variety of effects ranging from moderate acceleration of LVP fall to marked deceleration of LVP fall. Acceleration of LVP fall in response to a load elevation is associated with normal cardiac function, while slowing of LVP fall is associated with impaired cardiac function. Similar but opposite effects are observed with reductions of systolic LVP. Effects of changes in systolic LVP on time constant tau reveal a fair correlation with systolic elastance (Ees), peak dP/dtmax and regional fractional shortening (or ejection fraction). There is an excellent correlation with measured isovolumetric LVP, indicating that contraction-relaxation coupling is close when contractility is expressed in terms of peak isovolumetric pressure. Assessment of contractility with systolic LVP-relaxation relation is precise and load independent and can be performed with the sole use of a high-fidelity pressure gauge positioned in the left ventricular cavity.

Animals↗
PubMed1997

Phasic coronary flow characteristics in patients with constrictive pericarditis: comparison with restrictive cardiomyopathy.

BACKGROUND: Phasic coronary flow characteristics have been reported in patients with aortic valve disease and hypertrophic cardiomyopathy. The purpose of this study was to assess the differences in coronary flow characteristics between patients with constrictive pericarditis and those with restrictive cardiomyopathy. METHODS AND RESULTS: The study populations consisted of 7 case patients with constrictive pericarditis, 8 with restrictive cardiomyopathy, and 11 control subjects with chest pain and normal coronary arteries. Five minutes after injection of 3 mg of isosorbide dinitrate, phasic coronary flow velocity patterns were analyzed in the proximal segment of the angiographically normal left anterior descending coronary artery at rest using a 0.014-in, 15-MHz Doppler guidewire. Coronary flow reserve was obtained from the ratio of adenosine-induced (0.14 mg x kg(-1) x min(-1) I.V.) hyperemic/baseline time-averaged peak velocity. Although in case patients with constrictive pericarditis and restrictive cardiomyopathy maximal hyperemic time-averaged peak velocity (21+/-8 and 31+/-17 versus 60+/-19 cm/s, respectively; P<.001) and coronary flow reserve (1.3+/-0.4 and 1.6+/-0.6 versus 3.6+/-0.4, respectively, P<.001) were significantly lower than in control subjects, there were no significant differences in these indexes between the two groups of case patients. Velocity half-time of diastolic flow velocity corrected by square root(RR), which indicates deceleration of diastolic flow, in the groups of case patients with constrictive pericarditis and restrictive cardiomyopathy was significantly less than that in control subjects (6.2+/-2.6 and 10.6+/-1.5 versus 16.9+/-2.7, respectively; P<.001); this was also significantly smaller in constrictive pericarditis than restrictive cardiomyopathy (P<.001). This index <9.5 could distinguish constrictive pericarditis from restrictive cardiomyopathy with a sensitivity of 86% and a specificity of 88%. Furthermore, time from the beginning of diastole to diastolic peak velocity corrected by square root(RR) indicating acceleration of diastolic flow velocity in constrictive pericarditis was significantly less than that in restrictive cardiomyopathy and control subjects (2.8+/-1.2 versus 4.8+/-0.8 and 4.4+/-0.6, respectively; P<.001). CONCLUSIONS: Although coronary flow reserve is limited in both constrictive pericarditis and restrictive cardiomyopathy because of restriction of hyperemic response, rapid acceleration and more rapid deceleration of diastolic flow velocity are more characteristic in constrictive pericarditis than in restrictive cardiomyopathy.

Adult↗
PubMed1999

Diastolic dysfunction in hypertensive heart disease is associated with altered myocardial metabolism.

BACKGROUND: Hypertension is an important clinical problem and is often accompanied by left ventricular (LV) hypertrophy and dysfunction. Whether the myocardial high-energy phosphate (HEP) metabolism is altered in human hypertensive heart disease and whether this is associated with LV dysfunction is not known. METHODS AND RESULTS: Eleven patients with hypertension and 13 age-matched healthy subjects were studied with magnetic resonance imaging at rest and with phosphorus-31 magnetic resonance spectroscopy at rest and during high-dose atropine-dobutamine stress. Hypertensive patients showed higher LV mass (98+/-28 g/m2) than healthy control subjects (73+/-13 g/m2, P<0.01). LV filling was impaired in patients, reflected by a decreased peak rate of wall thinning (PRWThn), E/A ratio, early peak filling rate, and early deceleration peak (all P<0. 05), whereas systolic function was still normal. The myocardial phosphocreatine (PCr)/ATP ratio determined in patients at rest (1. 20+/-0.18) and during stress (0.95+/-0.25) was lower than corresponding values obtained from healthy control subjects at rest (1.39+/-0.17, P<0.05) and during stress (1.16+/-0.18, P<0.05). The PCr/ATP ratio correlated significantly with PRWThn (r=-0.55, P<0.01), early deceleration peak (r=-0.56, P<0.01), and with the rate-pressure product (r=-0.53, P<0.001). CONCLUSIONS: Myocardial HEP metabolism is altered in patients with hypertensive heart disease. In addition, there is an association between impaired LV diastolic function and altered myocardial HEP metabolism in humans. The level of myocardial PCr/ATP is most likely determined by the level of cardiac work load.

Adenosine Triphosphate↗
PubMed2006

Association of hemoglobin delivery with left ventricular structure and function in hypertensive patients: Losartan Intervention for End Point Reduction in Hypertension Study.

Several studies have shown associations of high levels of hemoglobin (Hgb) or blood viscosity with cardiac events and with left ventricular (LV) hypertrophy (LVH). To assess the relations of LV mass and function with Hgb delivery (ie, the physiological carrier of oxygen), we calculated the product of Hgb concentration and Doppler-derived cardiac output in 864 hypertensive participants with electrocardiographic LVH (359 women) in the Losartan Intervention for End Point Reduction in Hypertension echocardiography substudy. Among women, Hgb delivery was positively related to internal dimension, septal and posterior wall thicknesses, LV mass, endocardial and midwall fractional shortening, and peak A wave velocity and negatively to total peripheral resistance index, E/A ratio, deceleration time, and the isovolumic relaxation time. Among men, Hgb delivery was positively related to LV internal dimension, LV mass, and A velocity, and negatively to LV midwall shortening, relative wall thickness, peripheral resistance index, and E/A ratio. In multivariable analyses that adjusted for age, diastolic blood pressure, body mass index, and total cholesterol, hemoglobin delivery in women was related positively to LV fractional shortening, midwall shortening, LV mass mitral valve A velocity, and LV internal dimension and negatively to mitral valve deceleration time and isovolumic relaxation time. Among men, Hgb delivery had positive independent relations to mitral valve A velocity, LV internal dimension, midwall shortening, and LV mass and negative relations to the E/A ratio and relative wall thickness. Thus, in hypertensive LVH, higher oxygen delivery capacity is associated with higher LV mass and impaired early diastolic LV filling.

Aged↗
PubMed1997

Can trasmitral Doppler E-waves differentiate hypertensive hearts from normal?

Physiological models of transmitral flow predict E-wave contour alteration in response to variation of model parameters (stiffness, relaxation, mass) reflecting the physiology of hypertension. Accordingly, analysis of only the E-wave (rather than the E-to-A ratio) should be able to differentiate between hypertensive subjects and control subjects. Conventional versus model-based image processing methods have never been compared in their ability to differentiate E-waves of hypertensive subjects with respect to age-matched control subjects. Digitally acquired transmitral Doppler flow images were analyzed by an automated model-based image processing method. Model-derived indexes were compared with conventional E-wave indexes in 22 subjects: 11 with hypertension and echocardiographically verified ventricular hypertrophy and 11 age-matched nonhypertensive control subjects. Conventional E-wave indexes included peak E, E, and acceleration and deceleration times. Model-based image processing-derived indexes included acceleration and deceleration times, potential energy index, and damping and kinematic constants. Intergroup comparison yielded lower probability values for model-based compared with conventional indexes. In the subjects studied, Doppler E-wave images analyzed by this automated method (which eliminates the need for hand-digitizing contours or the manual placement of cursors) demonstrate diastolic function alteration secondary to hypertension made discernible by model-based indexes. The method uses the entire E-wave contour, quantitatively differentiates between hypertensive subjects and control subjects, and has potential for automated noninvasive diastolic function evaluation in large patient populations, such as hypertension and other transmitral flow velocity-altering pathophysiological states.

Aged↗
PubMed1999

Effects of candesartan and cilazapril on rats with myocardial infarction assessed by echocardiography.

The purpose of this study was to compare the angiotensin II type 1 receptor antagonist candesartan cilexitil (candesartan) and the angiotensin-converting enzyme inhibitor cilazapril on cardiac function, assessed by Doppler echocardiography and cardiac gene expression associated with cardiac remodeling, in rats with myocardial infarction. Candesartan or cilazapril was administered after myocardial infarction. At 1 and 4 weeks after myocardial infarction, cardiac function and mRNA expression in noninfarcted myocardium were analyzed. Candesartan and cilazapril equally prevented increases in hypertrophy in noninfarcted myocardium, left ventricular dilatation, and ejection fraction at 4 weeks. The E-wave/A-wave velocity ratio and the rate of E-wave deceleration, measures of diastolic function, increased to 9.2+/-0.6 and 26.3+/-2. 6 m/s2 at 1 week after myocardial infarction. Candesartan and cilazapril, administered at a dose of 1 mg/kg per day, prevented increases in E-wave/A-wave velocity ratio and E-wave deceleration at 1 and 4 weeks. Candesartan and cilazapril significantly suppressed increased mRNA expression of beta-myosin heavy chain, alpha-skeletal actin, and atrial natriuretic peptide in noninfarcted ventricle at 1 and 4 weeks and expression of collagen I and III at 4 weeks to a similar extent. When given at a dose of 10 mg/kg per day, both candesartan and cilazapril prevented cardiac dysfunction and gene expression to the same extent as when given at 1 mg/kg per day. In conclusion, Doppler echocardiography showed that candesartan and cilazapril equally improved systolic and diastolic function and that ventricular remodeling accompanied modulation of cardiac gene expression.

Angiotensin Receptor Antagonists↗
PubMed2001

Maternal diastolic dysfunction and left ventricular geometry in gestational hypertension.

The objective of this study was to evaluate diastolic parameters and left ventricular geometry in gestational hypertension. Twenty-one consecutive pregnant women with gestational hypertension and 21 normotensive women matched for age and gestational age were enrolled in the third trimester of gestation. Echocardiographic and uterine color Doppler evaluations were performed. Systolic, diastolic, and mean blood pressure, total vascular resistance (TVR), and uterine resistance index were higher in hypertensive women than in control subjects (P<0.01). Left atrial function and cardiac output were significantly lower in gestational hypertension (P<0.01). Patients with gestational hypertension had longer left ventricular isovolumetric relaxation time (IVRT) (P<0.0001); lower velocity-time integral of the A wave (P<0.05) and of the diastolic pulmonary vein flow (P<0.05); and higher velocity-time integral of the reverse pulmonary vein flow (P<0.05). Systolic fraction of the pulmonary vein flow was higher in women with gestational hypertension than in control subjects (P<0.01); the difference in duration of pulmonary vein flow and A wave was closer to 0 in gestational hypertension (P<0.0001). Altered left ventricular geometry was found in 100% of hypertensive patients and in 19.05% of normotensive patients (P<0.001). IVRT, left ventricular end-systolic volume, atrial function, and uterine resistance index were directly related to TVR (P<0.01); deceleration time of the E wave showed a quadratic correlation with TVR (P<0.01). Gestational hypertension is characterized by an altered cardiac geometric pattern of concentric hypertrophy. The altered geometric pattern assessed during gestational hypertension is associated, in our study, with depressed systolic function, high TVR, altered diastolic function, and left atrial dysfunction. Deceleration time of the E wave, IVRT, and left atrial fractional area change, found in concomitance with the highest TVR, may be useful in the evaluation of cardiac function and hemodynamics present in pregnancy-induced hypertension.

Adult↗
PubMed1991

Simulated blood flow and the effects on prostacyclin production in the dog femoral artery.

Effects of blood flow on the production of prostacyclin (PGI2) were examined in the canine femoral artery perfused ex vivo. Each artery was perfused in situ with medium 199, under conditions of simulated blood flow. To simulate the normal and abnormal blood flow waveforms at the same mean flow rate, we developed a flow apparatus capable of making various waveforms by changing the duration when the electromagnetic valve in the circuit was open. Group I (n = 7) was exposed to a steep acceleration waveform followed by a steep deceleration, as the normal flow waveform; group II (n = 7) was exposed to a gentle sloping waveform in the deceleration phase, as the abnormal flow waveform. PGI2 was measured as 6-ketoprostaglandin F1 alpha. PGI2 production was estimated as the cumulative production for the first 5 minutes (acute response) and as the production rate after the first 30 minutes (stable production rate). Under conditions of normal flow, the acute response was 5.87 +/- 2.16 ng/cm2/5 min, whereas under conditions of abnormal flow, the rate was 2.20 +/- 0.27 ng/cm2/5 min (p less than 0.01). Stable production rates were 82.5 and 37.5 pg/cm2/min, respectively (p less than 0.05). Both the acute response and the stable production rate of PGI2 production were greater under conditions of simulated normal flow as compared with findings in the case of an abnormal flow. Our working hypothesis is that the decreased production of PGI2, as well as a deterioration in the implanted graft, under conditions of abnormal blood flow leads to a loss of late patency of the reconstructed arteries.

6-Ketoprostaglandin F1 alpha↗