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PubMed2006

Plasma natriuretic peptide levels reflect changes in heart failure symptoms, left ventricular size and function after surgical mitral valve repair.

BACKGROUND AND AIM: N-terminal pro-B-type natriuretic peptide (NT-proBNP) has diagnostic and prognostic value in patients with heart failure. The present prospective study was designed to assess whether changes in NT-proBNP levels after surgical mitral valve repair reflect changes in heart failure symptoms and changes in left atrial size, left ventricular size and left ventricular function. METHODS: The study population consisted of 22 patients (mean age: 62.8 +/- 14.2 years, 68% male) undergoing surgical mitral valve repair. Serial NT-proBNP measurements, transthoracic echocardiography and New York Heart Association (NYHA) class assessment were performed before and 6 months after surgery. RESULTS: All patients underwent successful mitral valve repair and no patients died during follow-up. The decrease in NT-proBNP level was associated with the reduction in left atrial dimension (r = 0.72, P < 0.001), left ventricular end-systolic dimension (r = 0.63, P = 0.002), left ventricular end-diastolic dimension (r = 0.46, P = 0.031), and the increase in fractional shortening (r = - 0.63, P = 0.002). Finally, patients with decreasing NT-proBNP levels revealed a significant improvement in heart failure symptoms (NYHA class). CONCLUSION: Changes in NT-proBNP after surgical mitral valve repair reflect changes in heart failure symptoms and changes in left atrial and ventricular dimensions and function.

Aged↗
PubMed1983

The effect of atrial pacing-induced tachycardia on left ventricular contractile function in conscious newborn and adult sheep.

In order to determine if an increase in heart rate is associated with an increase of left ventricular contractile function during the neonatal period we recorded phasic and mean aortic blood pressure, left atrial mean or left ventricular end diastolic pressure, phasic left ventricular blood pressure, aortic blood flow velocity and the instantaneous first derivatives of left ventricular blood pressure (dP/dt) and aortic blood flow velocity (dV/dt) during pacing-induced tachycardia in conscious newborn and adult sheep. There was a significant positive linear correlation between heart rate and both indices of contractility (dP/dt and dV/dt) in both age groups. Left ventricular end diastolic pressure was unchanged except for a decrease at the most rapid heart rate in the newborns. There was no change in aortic mean blood pressure during the study. Our data demonstrate that an increase of heart rate is associated with an increase of left ventricular contractile function in conscious neonatal and adult sheep. Investigations of the effects of potential inotropic agents on left ventricular contractile performance in newborns and adults must evaluate the independent effect of any simultaneously occurring increase in heart rate.

Animals↗
PubMed1996

Circadian variation of left ventricular diastolic function in healthy people.

AIM: To assess whether left ventricular function shows circadian variation in healthy people. SUBJECTS AND METHODS: 10 healthy men (7) and women (3) aged 35-50 underwent M mode echocardiography of the left ventricle and Doppler velocimetry of transmitral flow at 4 h intervals over 24 h. The participants were in hospital over the study period and their diet, meal times, and sleeping hours were standardised as far as possible. MEASUREMENTS: Heart rate, blood pressure, left ventricular and atrial diameters, fractional shortening, peak early and late transmitral velocities, time from the second heart sound to the early diastolic velocity peak (relaxation time), isovolumic relaxation period, acceleration and deceleration of the early transmitral flow, atrial filling fraction. RESULTS: A circadian rhythm was observed in heart rate and blood pressure, but neither the left ventricular diameters and systolic function nor the left atrial size showed statistically significant diurnal trends. The relaxation time (mean (SD)) measured 144 (16) ms at 2 pm, 144 (21) ms at 6 pm, 149 (22) ms at 10 pm, 168 (23) ms at 2 am, 174 (28) ms at 6 am, and 151 (21) ms at 10 am (P = 0.009). Diurnal rhythms were seen also in the isovolumic relaxation period (P = 0.003) and in the acceleration of the early diastolic transmitral flow (P = 0.037); the lowest and highest values of flow acceleration were observed during the nocturnal and daytime hours, respectively. CONCLUSIONS: The Doppler indices of left ventricular filling in healthy people show diurnal changes suggestive of a circadian rhythm in the rate of left ventricular relaxation. The most likely underlying mechanism is the day-night cycle in sympathoadrenal activity.

Adult↗
PubMed1986

Continuous measurement of intramyocardial pH: correlation to functional recovery following normothermic and hypothermic global ischemia.

The continuous measurement of intramyocardial pH was used to follow the progression of ischemia and was correlated to the recovery of left ventricular function following normothermic (38 degrees C) and hypothermic (25 degrees C) global ischemia. New miniature myocardial transducers, which incorporate fiberoptic technology and dual pH- and temperature-sensing capability, were placed into the left ventricular free wall and septum of 52 sheep undergoing cardiopulmonary bypass. Left ventricular stroke work as a function of mean left atrial pressure curves were generated before and after cardiopulmonary bypass by volume loading with whole blood. Functional recovery was determined by the ratio of the integrals of the preischemic and postischemic function curves. Control sheep (N = 11) did not undergo ischemia. Three groups (N = 41) underwent aortic cross-clamping until pH reached 7.0, 6.8, or 6.6. The preischemic myocardial pH averaged 7.42 +/- 0.01. Following both normothermic and hypothermic global ischemia, no significant difference was demonstrated in recovery of function between control (pH 7.4) and pH 7.0 groups at either temperature. However, recovery of function of the pH 6.8 and pH 6.6 groups was significantly decreased (p less than 0.01) versus control and pH 7.0 groups at both temperatures. No significant difference in recovery of function was demonstrated at any pH level when normothermic versus hypothermic groups were compared. However, hypothermia provided increased time (p less than 0.001) before each level of function was reached with a slower rate of change of pH (p less than 0.01) compared with the corresponding same pH group in sheep undergoing normothermic (38 degrees C) cardiopulmonary bypass.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Study on left atrial contractile performance--participation of Frank-Starling mechanism.

We estimated the magnitude of the left atrial contraction in 28 patients with ischemic heart disease by calculating the biplane cineangiographic volumes of the left atrium. The left atrial contraction contribution to the left ventricular stroke volume (ml/m2, Y axis) correlated inversely with the left ventricular ejection fraction (%, X axis), yielding an equation: Y = -0.31X + 43.7 (n = 28, r = -0.56, p less than 0.001). The result indicates that the left ventricular filling is compensated by the augmented atrial contraction in case of impaired left ventricular function. We defined the left atrial volume at the beginning of the atrial contraction (LAVd, ml/m2) as the "preload" of the left atrium, and we also defined the volume expelled by the active atrial contraction (delta LAVa, ml/m2) as the stroke volume of the left atrium. The stroke volume (Y) correlated positively with the "preload" (X), yielding an equation: Y = 0.48X - 1.3 (n = 28, r = 0.80, p less than 0.001). We then defined the left ventricular end-diastolic pressure, the peak of the a-wave, as the "afterload" of the left atrium, and we studied the "afterload"-stroke volume relations in the left atrium. However as expected, a reasonable relationship between them was difficult to form. Consequently, we showed that an increase in the "preload" of the left atrium augmented the stroke volume of the left atrium, which means that Frank-Starling mechanism is operative in the left atrium.

Adult↗
PubMed1995

Hemodynamics of different degrees of right heart bypass: experimental assessment.

BACKGROUND: Although their assessment could be of the utmost importance to determine the surgical treatment for patients with univentricular hearts, differences in ventricular performance between partial and complete right heart bypass remain to be defined. METHODS: Three different degrees of right heart bypass were investigated in 5 mongrel dogs: (1) superior vena cava to both pulmonary arteries shunt (SCP); (2) inferior vena cava to both pulmonary arteries shunt (ICP); and (3) both venae cavae to both pulmonary arteries shunt (BCP). Hemodynamic studies included evaluation of the cardiac index and left atrial pressure as a function of the degree of right heart bypass. RESULTS: By maintaining the mean left atrial pressure at 5 mm Hg, cardiac indexes were 1.98 +/- 0.25, 1.67 +/- 0.29, and 1.33 +/- 0.21 L.min-1.m-2 for SCP, ICP, and BCP shunts, respectively (p = 0.001). When keeping the cardiac index constant, mean left atrial pressures were 5.2 +/- 0.8, 5.5 +/- 0.9, and 7 +/- 0.7 mm Hg for SCP, ICP, and BCP shunts, respectively (p = 0.001). CONCLUSIONS: Increasing degrees of right heart bypass are associated with a significant decrease in ventricular performance in this experimental model.

Animals↗
PubMed2004

[Concomitant treatment of atrial fibrillation in open-heart surgery patients: late rhythm and functional results].

BACKGROUND: In recent years left atrial approaches have become popular because of technical simplicity, reproducibility and minor surgical trauma compared to the standard maze procedure. We analysed mid-term results of intraoperative left radiofrequency ablation of atrial fibrillation. METHODS: From February 1998 to August 2002, 206 patients (mean age 59.1 +/- 10.2 years) scheduled for open-heart surgery underwent combined treatment of atrial fibrillation at our Institution. In 163 patients (79.1%) a standard left epicardial approach was performed while 43 patients (20.9%) needed a totally endocardial approach. RESULTS: All patients but 3 underwent mitral valve surgery (104 repair and 99 replacement). Hospital mortality was 1.9%. Actuarial freedom from atrial fibrillation was 78% at 2 years and 74% at 4 years. At 4 years survival was 94% and freedom from neurological events was 98%. All patients with stable sinus rhythm 3 months after surgery recovered biatrial contractility. CONCLUSIONS: Left radiofrequency ablation of atrial fibrillation is effective in restoring sinus rhythm and normal atrial function. Combined atrial fibrillation treatment should be considered in all patients undergoing open-heart surgery.

Actuarial Analysis↗
PubMed1994

Effect of gender on the left ventricular diastolic performance during isometric handgrip exercise in normal individuals.

To evaluate the effects of gender and isometric handgrip exercise on left ventricular diastolic function in normal individuals, atrial and rapid filling fraction were investigated using M-mode echocardiography in 35 postmenopausal women and 31 age-matched men. There were no significant differences in heart rate, mean blood pressure, atrial filling fraction, and rapid filling fraction at rest between women and men. When the amount of change in hemodynamic variable during exercise was compared, there were no significant differences in heart rate and mean blood pressure between women and men. But the increase in atrial filling fraction and the decrease in rapid filling fraction were significantly larger in women than in men. These data suggest that left ventricular diastolic function is restricted in postmenopausal women, and left atrial booster pump action is mobilized when afterload is increased during isometric handgrip exercise.

Aged↗
PubMed2005

Effects of omapatrilat on cardiac nerve sprouting and structural remodeling in experimental congestive heart failure.

BACKGROUND: Congestive heart failure (CHF) results in decreased cardiac sympathetic innervation. OBJECTIVES: The purpose of this study was to test the hypothesis that therapy with the vasopeptidase inhibitor omapatrilat (OMA) attenuates cardiac neuronal remodeling in CHF. METHODS: We induced CHF in dogs with rapid ventricular pacing for 5 weeks with (CHF+OMA group, n = 8) or without (CHF group, n = 10) concomitant OMA treatment (10 mg/kg twice daily). Cardiac catheterization and echocardiography were performed to determine cardiac structure and hemodynamic parameters. Myocardial nerve density was determined by immunocytochemical staining with anti-growth associated protein 43 (GAP43) and anti-tyrosine hydroxylase (TH) antibodies. Seven normal dogs were used as histologic controls. RESULTS: In the CHF group, ascites developed in 3 dogs and 4 dogs died, compared with no ascites or death in the CHF+OMA group (P = .07). In the 6 CHF dogs that survived, all had atrial fibrosis, severely depressed left ventricular systolic function, and increased atrial and ventricular chamber size. OMA treatment decreased the atrial and ventricular chamber sizes and the degree of atrial fibrosis. Most CHF dogs showed severe myocardial denervation, although some showed normal or abnormally high nerve counts. OMA treatment prevented heterogeneous reduction of nerve density. The left ventricular TH-positive nerve densities were 128 +/- 170 microm(2)/mm(2), 261 +/- 185 microm(2)/mm(2), and 503 +/- 328 microm(2)/mm(2) (P < .05), and the atrial GAP43-positive nerve densities were 1,683 +/- 1,365 microm(2)/mm(2), 305 +/- 368 microm(2)/mm(2), and 1,278 +/- 1,479 microm(2)/mm(2) (P < .05) for the control, CHF, and CHF+OMA groups, respectively. CONCLUSION: CHF results in heterogeneous cardiac denervation. Long-term OMA treatment prevented the reduction of nerve density and promoted beneficial cardiac structural remodeling.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1996

[Anticoagulant related hemorrhage and thromboembolism after valvular surgery].

We reviewed anticoagulant related hemorrhage (ACRH) and thromboembolism (TE) in 84 patients after valvular surgery. There were 45 females and 39 males with a mean age of 51.8 years (range 30.5-71.2 years), who underwent valvuloplasty in 14, bioprosthetic valve replacements in 17, mechanical valve replacements in 13. A mean period from the operation to the event were 2.7 years (range 0.01-12.3 years). There were 25 ACRH events after one valvuloplasty, 4 bioprosthetic valve replacements, 20 mechanical valve replacements. About half of them, the prothrombin time were less than 25%, which was considered the effect of warfarin is high, and 8% of them had infective endocarditis (IE) previously. There were 59 TE events after 13 valvuloplasties, 13 bioprosthetic valve replacements, 33 mechanical valve replacements. In the patients with atrial fibrillation, TE occurred irrespective of operative procedures. And in the patients with mechanical valve, severely impaired left ventricular function and past history of IE, thrombi of left ventricule were caused of TE. It was suggested that past history of IE was a risk factor ACRH and TE, and severely depressed left ventricular function and atrial fibrillation were for TE.

Adult↗
PubMed1992

Improvement in left ventricular systolic function after successful radiofrequency His bundle ablation for drug refractory, chronic atrial fibrillation and recurrent atrial flutter.

Incessant supraventricular tachyarrhythmia may lead to a reversible impairment of left ventricular (LV) function. This issue was investigated in 10 patients (aged 64 +/- 13 years) who underwent radiofrequency His bundle ablation for control of drug refractory, chronic atrial fibrillation (n = 9) and recurrent atrial flutter (n = 1). LV function was assessed by 2-dimensional guided M-mode echocardiography within 24 hours (baseline) and 49 +/- 18 days (follow-up) after successful ablation, both during VVI pacing at 70 beats/min. Fractional shortening increased from 28 +/- 9% at baseline to 35 +/- 8% at follow-up (p = 0.006). This increase in fractional shortening was due to a significant reduction of end-systolic diameter from 41 +/- 10 to 36 +/- 10 mm (p = 0.02), whereas there was no appreciable change in end-diastolic diameter (56 +/- 7 to 55 +/- 10 mm; p = 0.5). These changes were substantially greater in patients with baseline impairment of LV function (fractional shortening less than 27%). Fractional shortening increased by 12% (p = 0.14) in patients with normal LV function (n = 5) and by 44% (p = 0.02) in those with impaired LV function at baseline (n = 5). The greater increase in fractional shortening in patients with preexisting LV impairment was due to a more pronounced decline in end-systolic dimensions (-11.9%; p = 0.08) compared with that of patients with normal LV function at baseline (-9.21%; p = 0.2). End-diastolic diameter showed no significant change in either group (-3.53% [p = 0.8] and -0.58% [p = 0.4]).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed2007

The effect of successful electrical cardioversion on left ventricular diastolic function in patients with persistent atrial fibrillation: a tissue Doppler study.

BACKGROUND: Changes in mitral inflow and pulmonary venous flow after electrical cardioversion (ECV) in patients with persistent atrial fibrillation (AF) were showed in many former studies. In our study we investigated the effects of ECV on diastolic parameters by using tissue Doppler imaging (TDI) in patients with persistent AF. METHODS: Forty-one (24 women) consecutive patients underwent successful elective ECV for nonvalvular persistent AF, and maintained sinus rhythm for 1 month were enrolled to the study. Transthoracic echocardiography was applied to all patients before, 24 hours after and 1 month after ECV. Mitral annular TDI parameters were also measured with mitral inflow, pulmonary venous flow, and other standard echocardiographic measurements. RESULTS: No differences in peak myocardial early velocity (Em), deceleration time of Em, and myocardial isovolumic relaxation time measured from mitral lateral annulus before, 24 hours after, and one month after ECV were found. Peak myocardial late velocity measured 24 hours after ECV increased significantly at the end of 1 month. CONCLUSION: There were not any changes in LV diastolic function except restoration of atrial mechanical contraction following ECV in patients with persistent AF.

Aged↗
PubMed2002

Demonstration of a left atrial input to the atrioventricular node in humans.

BACKGROUND: During right atrial stimulation, the anterior and posterior approaches provide inputs to the atrioventricular (AV) node. The purpose of the present study was to determine how activation proceeding from the left atrium reaches the AV node. METHODS AND RESULTS: We studied AV nodal conduction during right and left atrial (coronary sinus) stimulation in 46 patients (27 women and 19 men; mean age, 46+/-4 years) who had structurally normal hearts. At an identical cycle length (600 ms), left atrial stimulation resulted in shorter A-H intervals than right atrial stimulation (73+/-3 ms versus 99+/-3 ms; P<0.05). In addition, atrial electrograms recorded close to the His bundle changed from near to far field potentials when stimulation was shifted to the left atrium. The A-H interval prolonged as the site of pacing was progressively moved from the distal to the proximal coronary sinus. During constant pacing from the distal coronary sinus, atrial activation close to the His bundle could be advanced by late extrastimuli delivered at the anterior and posterior approaches (up to 11+/-2 ms and 9+/-1 ms, respectively), without altering His bundle activation time. In contrast, late extrastimuli delivered at the inferoparaseptal mitral annulus advanced both the A and H electrograms in 19 of 20 patients, which is consistent with a left-sided input to the AV node. Right and left atrial stimulation resulted in similar AV nodal function. CONCLUSION: The mitral annulus provides a left atrial input to the human AV node.

Atrial Flutter↗
PubMed1995

[Recent morphofunctional findings on the left atrium: their relations to thromboembolic risk].

In the past, the left atrial appendage has been considered a "useless" structure but associated to thromboembolic complications; its physiologic role is still undefined. Owing to its great distensibility, left atrial appendage positively influences atrial compliance and left ventricular performances. In addition this structure seems to play an important role in circulatory homeostasis by the release of atrial natriuretic factor in response to volume loading and atrial stretch. Transesophageal echocardiography provides a detailed anatomical characterization of this structure and, by means of Doppler flow velocities recordings, supplies relevant functional data. Despite their anatomical contiguity, the left atrium and atrial appendage result from a separate embryonic development; likewise, their function may differentiate. In the left atrial appendage a quadriphasic flow pattern has been described in subjects with sinus rhythm; however, as we reported, in some patients a more complex Doppler pattern can be observed, with an additional systolic forward flow wave which is presumably due to reflection phenomena. In patients with atrial fibrillation, an irregular flow pattern has been detected, which is mostly dependent on the duration of the arrhythmia, the underlying heart disease and the left atrial pressure. By transesophageal echocardiography a clear correlation has been established between the left atrial appendage slow flow and the occurrence of thromboembolic events; however, while waiting data from large studies, stratification of patients according to thromboembolic risk and decisions about anticoagulant prophylaxis should be performed by clinical information and transthoracic echocardiographic findings. No clinical or echocardiographic parameter has been found to be predictive of the thromboembolic events after cardioversion; in this setting the exclusion of atrial or atrial appendage thrombi by transesophageal echocardiography does not rule out the need for anticoagulation in patients with atrial fibrillation undergoing electrical or pharmacological cardioversion.

Atrial Function, Left↗
PubMed1992

Regional atrial distensibility.

We studied 12 open-chest dogs to determine whether there are regional differences in left atrial distensibility. Sonomicrometer crystal pairs were used to measure the anteroposterior diameters of the left atrial body and appendage simultaneously over a wide range of intracardiac pressures and volumes obtained by intravenous saline infusion. Left atrial pressure-natural strain data for the body and appendage were fitted to an exponential function. The mean coefficient of the left atrial monoexponential pressure-strain relationship was greater for the body than appendage (3.1 +/- 1.1 vs. 1.9 +/- 0.7 mmHg, P less than 0.01). The Y-intercepts were not significantly different (5.2 +/- 1.7 vs 4.9 +/- 1.8 mmHg). The maximum minus minimum left atrial dimension, an index of the reservoir function of the atrium, increased with volume infusion in both the body and appendage and was significantly greater in the appendage than body at each level of left atrial pressure. Similarly, atrial systolic shortening fraction increased with volume infusion, and regional shortening was greater in the appendage than the body at each level of left atrial pressure. We conclude that regional differences in atrial distensibility exist in vivo and may play an important role in modulating systolic and diastolic function of the left atrium.

Animals↗
PubMed1993

Influence of pericardium on left atrial compliance and pulmonary venous flow.

We studied seven open-chest anesthetized dogs to test the hypothesis that left atrial (LA) compliance is increased after pericardiectomy and to determine the effect of pericardiectomy on left atrial reservoir and conduit function. Two orthogonal sonomicrometer crystal pairs were used to estimate LA volume, and LA filling was assessed with a pulmonary vein (PV) flow probe. The left ventricular (LV) systolic (JFTI) and diastolic (KFTI) PV flow integrals were used as indexes of LA reservoir and conduit function, respectively. Diastolic LV transmitral flow was assessed with transesophageal Doppler echocardiography. Data were acquired over a wide range of intracardiac pressures and volumes obtained by intravenous hetastarch infusion both before and after pericardiectomy. The mean dynamic stiffness constant of the LA diastolic pressure-volume relation was significantly greater before pericardiectomy than afterwards (0.15 +/- 0.04 vs. 0.08 +/- 0.03 ml-1, P < 0.05). Data were analyzed before and after pericardiectomy at three matched levels of left atrial pressure (LAP; 7, 13, and 20 mmHg). The J-to-KFTI ratio increased significantly with volume infusion and was significantly less after pericardiectomy than before (1.2 +/- 0.7 vs. 1.2 +/- 0.6, 1.8 +/- 0.6 vs. 2.2 +/- 0.9, and 2.0 +/- 0.8 vs. 2.6 +/- 0.9 at low, mid, and high levels of LAP, respectively; P < 0.05 at mid and high levels of LAP). Peak early transmitral velocity increased with both volume infusion and pericardiectomy. We conclude that pericardiectomy increases LA compliance and early LV filling rate and is accompanied by a relatively greater augmentation in conduit than reservoir function of the left atrium.

Animals↗