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PubMed1982

Increased left atrial pressure does not alter renal function in the conscious primate.

To study the functional role of the atriorenal reflex in the nonhuman primate, we chronically instrumented six Macaca fascicularis with left atrial snares and left atrial and aortic catheters. After inserting a bladder catheter, we determined hemodynamic and renal responses of the conscious chair-restrained monkey to increased left atrial pressure. In 23 snare experiments, no significant changes in renal or cardiovascular function were observed even though left atrial pressure increased from 6.5 +/- 3.3 to 16.2 +/- 3.4 mmHg. The animals were subjected also to blood volume expansion with isoncotic isotonic dextran solutions (+15% of calculated blood volume). They responded normally to this volume stimulus. Conscious dogs prepared in the same manner as the nonhuman primate exhibited diuresis in response to elevations of atrial pressure. We conclude that left atrial stretch receptors are not importantly involved in volume homeostasis in the nonhuman primate.

Animals↗
PubMedDate not supplied

Time-course of left atrial performance during coronary artery occlusion followed by reperfusion in anesthetized dogs by densitometric analysis of digital atrioventriculographic images.

The left atrial (LA) function during coronary artery occlusion followed by reperfusion using densitometric analysis of digital atrioventriculographic images was evaluated. Eight anesthetized dogs underwent atrioventriculography at baseline, 10 and 60 min after left circumflex coronary artery (LCX) occlusion and 5, 30, 60, and 120 min of reperfusion. Time-density curves were obtained for LA and left ventricle (LV). The ratios of passive atrial video-densitometric change (VC) to total VC (Passive Ratio), and active VC to total VC (Active Ratio) were calculated. Left ventricular ejection fraction (LVEF), peak ejection rate (PER), and peak filling rate (PFR) were derived. Active Ratio, an index of atrial contraction, increased to 144%, and Passive Ratio decreased to 75% of baseline at 60 min of LCX occlusion. Two hours after reperfusion, both Active and Passive Ratios returned to control level. While LVEF reduced to 70%, PER to 67%, LV peak positive dP/dt to 88% of baseline at 60 min after occlusion, and remained depressed at 2 h after reperfusion. However, PFR, LV peak negative dP/dt and LV isovolumic pressure decay rate showed recovery at 2 h after reperfusion. There were significant correlations between PFR and Passive Ratio (r = 0.41), and between Active and Passive Ratios (r = 0.55). Thus, time-course of recovery of LV post-ischemic systolic and diastolic function was different. Return of LA function to control level during 2 h after reperfusion may be depend on recovery of LV diastolic function.

Animals↗
PubMed2002

Comparison between transesophageal echocardiography and transthoracic echocardiography with harmonic tissue imaging for left atrial appendage assessment.

BACKGROUND: Transesophageal echocardiography (TEE) is the method of choice for evaluating both anatomy and function of left atrial appendage (LAA). In contrast, conventional transthoracic echocardiography (TTE) does not result in images of sufficient quality to explore LAA. HYPOTHESIS: The aim of this study was to evaluate the potential role of TTE with harmonic frequency imaging (HFI) for assessing LAA normal anatomy and function. METHODS: The study group comprised 25 patients, (9 men, 16 women, mean age 51 years, range 20-82). The TTE as sessment of LAA both in fundamental frequency imaging (FFI) and HFI was performed using the apical two-chamber view, the longitudinal two-chamber view was used for TEE assessment of LAA. According to image quality, images were categorized into three classes: A: good quality, B: sufficient quality, C: poor quality. RESULTS: Transthoracic echocardiography conventional imaging allowed sufficient LAA visualization (class B) in only 5 of 25 patients (20%); the HFI resulted in adequate LAA visualization in 23 of 25 patients (92%). Images were of good quality (class A) in 18 of 23 patients and of sufficient quality (class B) in 5 of 23 patients. Transesophageal echocardiography achieved good quality images in 24 of 25 patients (96%). Average LAA maximum area determined by HFI and TEE was 3.46 +/-1.17 and 3.59 +/- 1.16 cm2, respectively; LAA minimum area was 1.81 +/- 0.98 and 1.77 +/- 0.97 cm2, respectively. Percent LAA area change was 51 +/- 16.5 and 50.9 +/- 16% with HFI and TEE, respectively. Statistical analysis showed no difference between the data obtained with the two methods. CONCLUSIONS: The results suggest that HFI TNE may be a useful tool for the exploration of LAA.

Adult↗
PubMed1993

Observations on plasma ANP levels during short-term transient myocardial ischemia produced by PTCA in patients with LAD stenosis.

Ten patients with coronary artery disease and stable angina (mean age fifty-seven) were included in the study. Five of the patients had normal left ventricular function, 5 had local hypokinesia or akinesia; 8 had one-stem and 2 had two-stem disease, but all had left anterior descending (LAD) lesions ranging from 75% to 100%. Ejection fraction varied between 35% and 75% (mean 59%). Immunoreactive atrial natriuretic polypeptide (ANP) levels in the femoral vein (FV) and the coronary sinus (CS) were measured before, immediately after, and up to twenty-four hours after percutaneous transluminal coronary angioplasty (PTCA) of the LAD. ANP secretion increased by 83% (FV) and 11% (CS) within minutes after PTCA and reached control levels after thirty to sixty minutes. In patients with hypokinesia of the anterior wall, ANP secretion was significantly lower, 48% (FV) and 11% (CS) respectively. ANP secretion during PTCA was higher in patients with concomitant increase in pulmonary capillary pressure (PCP) but was also observed without an increase of PCP, suggesting ventricular ANP secretion. IN conclusion, transient myocardial ischemia leads to immediate ANP secretion even in the absence of significant pressure elevation in the left atrium. As a part of the continuous medical education program of the American College of Angiology the second part of the paper reviews the mechanisms that allow the ischemic heart to counteract the ischemic condition and thus to escape from myocardial infarction. A review of this subject is presently not available in the literature.

Angina Pectoris↗
PubMedDate not supplied

Restoration of mechanical atrial function after electrical cardioversion of chronic atrial fibrillation in patients after surgical treatment of mitral valve disease--hemodynamic effects and prognostic value of maintenance of sinus rhythm.

There are controversies regarding the possibility of returning of A wave (mitral flow at left atrial contraction) after electroconversion (EC) in patients with persisting chronic atrial fibrillation in spite of successful surgical treatment of mitral valve disease. Twenty-four hours before successful EC, thereafter daily for 1 week and then on the 14th, 21st and 28th day and 6 months after EC, ECG, M-mode, two-dimensional and Doppler echocardiography were performed in 55 patients. A wave (>0.1 m/s) appeared on the 1st day in 31 patients, on the 2nd day in the next 6, on the 3rd in 5 patients, on the 4th and 5th days in 1 patient and on the 7th day in 4 patients. In 7 patients A wave did not restore. Maximum velocity of A wave increased from 0.48 +/- 0.22 to 0.86 +/- 0.28 m/s (p < 0.05) during the follow-up. In 92% of patients with A wave 24 h after EC, significant increases in stroke index from 35 +/- 12 to 47 +/- 15 ml/m2 (p < 0.04), ejection fraction from 46 +/- 9 to 55 +/- 8% (p < 0.01) and pulmonary acceleration time from 94 +/- 26 to 107 +/- 22 ms (p < 0.05) were observed. Sinus rhythm was still present on the 28th day in 34 patients (62%) and after 6 months in 31 patients (57%), all of them with A wave. observation shows the increase in pulmonary acceleration time, the decrease in the left atrial area and the increase in its systolic function in patients with A wave. Appearance of A wave determined the hemodynamic improvement, but we did not observe a correlation between maximal velocity of A wave and hemodynamic improvement. Appearance of A wave had a low predictive value for maintaining sinus rhythm (sensitivity 58% and specificity 45%). Relative increase in A wave velocity during the 1st week after EC correlated positively with long-term maintenance of sinus rhythm (r = 0.62; p < 0.001).

Adult↗
PubMed1993

Is white coat hypertension innocent? Structure and function of the heart in the elderly.

To evaluate the morphological and functional characteristics of the heart in elderly patients with white coat hypertension, we performed an echocardiographic study in 67 elderly individuals older than 60 years: 17 patients with white coat hypertension, 34 patients with true hypertension, and 16 normotensive control subjects. White coat hypertension was defined as a mean 24-hour ambulatory systolic blood pressure of less than 140 mm Hg associated with office hypertension. Cardiac responses to an isometric handgrip exercise test were used to evaluate left ventricular functional reserve. Left atrial dimension and left ventricular mass index were significantly greater in the white coat hypertension group than in the normotension group (P < .05) but were similar to values in the true hypertension group. Left ventricular diastolic function, expressed by peak late-early filling ratio of diastolic mitral flow, showed increasing impairment in the order of the normotension, white coat hypertension, and true hypertension groups (analysis of variance, P < .05); the ratio in the white coat hypertension group tended to be higher than that in the normotension group (unpaired t test, P = .054). The relation between fractional shortening and end-systolic stress did not shift downward after handgrip exercise in the white coat hypertension group, indicating that functional reserve in the left ventricle was maintained. Thus, patients with white coat hypertension had a moderately increased left atrial dimension and left ventricular mass in association with a tendency for disturbed diastolic function, although systolic functional reserve remained the same. These findings suggest that white coat hypertension in the elderly may not be innocent.

Aged↗
PubMed1989

Cardiac effects of atrial natriuretic peptide in subjects with normal left ventricular function.

The effects of atrial natriuretic peptide (ANP) infusion were determined in 9 subjects undergoing cardiac catheterization that did not disclose heart disease. Data were obtained at rest and during the steady-state phase of alpha-human-(1-28)-atrial natriuretic peptide infusion (0.5 micrograms/kg bolus, 0.05 micrograms/kg/min intravenously for 10 minutes). Mean blood pressure decreased from 105 +/- 3 to 98 +/- 4 mm Hg (p less than 0.05); pressure measurements and left ventricular (LV) angiograms suitable for analysis were available in 7 of 9 subjects at matched heart rate. The ANP infusion reduced LV end-diastolic and end-systolic volume indexes from 93 +/- 6 to 80 +/- 6 ml/m2 (p less than 0.01) and from 25 +/- 3 to 17 +/- 1 ml/m2 (p less than 0.05), respectively. The LV ejection fraction increased insignificantly from 72 +/- 5 to 77 +/- 4%. End-systolic pressure/volume ratio showed a slight but not significant increase (from 3 +/- 0.4 to 4 +/- 0.8). Initial plasma levels of ANP (48 +/- 12 pg/ml) increased to 1,890 +/- 423 pg/ml (p less than 0.001) during the infusion and individual hemodynamic responses were not related to plasma ANP concentrations. These data suggest that the administration of ANP has no negative effects on LV function and the ANP-induced changes on cardiac performance are related to the reduced cardiac load.

Adult↗
PubMed1998

Reversible left atrial dysfunction possibly due to afterload mismatch in patients with left ventricular dysfunction.

Limited data are available concerning the influence of altered loading conditions on left atrial (LA) function. In addition, the underlying mechanism of the augmentation of atrial filling (A) velocity (assessed by transmitral Doppler measurement) after treatment of heart failure has been less studied. Therefore, we examined various indexes of LA function during the depression of left ventricular (LV) filling pressure resulting from treatment of heart failure. Twelve patients with LV dysfunction (ejection fraction < 50%) underwent right heart catheterization and transthoracic echocardiography before and after optimal treatment of heart failure. LV/LA volume and ejection fraction and mitral and pulmonary venous flow velocities were measured. LV stiffness (substitute for LA afterload) was assessed by the ratio of LV filling pressure to LV end-diastolic volume. After treatment of heart failure, the mitral A velocity significantly increased (38 +/- 9 to 58 +/- 16 cm/sec, p < 0.005) and there was a distinct attenuation of the difference of the pulmonary venous and mitral A-wave duration (43 +/- 29 to -8 +/- 31 msec, p < 0.005). These findings were associated with a marked decrease in LV stiffness (0.12 +/- 0.04 to 0.05 +/- 0.02 mm Hg/ml, p = 0.0001) and an increase in LA ejection fraction (27% +/- 7% to 38% +/- 8%, p < 0.005). There was a significant curvilinear relation between LA ejection fraction and LV stiffness (r = 0.63, p < 0.01). The mitral A velocity correlated positively with LA ejection fraction (r = 0.77, p < 0.0001) and inversely with LV stiffness (r = -0.52, p < 0.01). The reversible LA dysfunction suggests that the initial LA dysfunction is due to LA afterload mismatch rather than intrinsic LA disease, which also contributes to the augmentation of the mitral A velocity after heart failure treatment.

Atrial Function, Left↗
PubMed2002

Echocardiographic evidence of atrial myopathy in amyloidosis: a case report.

Cardiac involvement occurs in up to 50% of patients with primary amyloidosis. Diffuse amyloid deposits lead to impairment of myocardial systolic and diastolic function. Due to the severe left ventricular diastolic abnormality, left atrial contribution to left ventricular stroke volume remains critical. We report a case of primary amyloidosis where we assessed non-invasively left atrial systolic function.

Aged↗
PubMed1993

Atrial ejection force: a noninvasive assessment of atrial systolic function.

OBJECTIVES: The purpose of this study was to define atrial ejection force and to develop a method for its noninvasive measurement from echocardiographic data. BACKGROUND: Assessment of diastolic function through measurement of the components of ventricular filling has largely neglected the vigor of atrial systole, in part because this has been difficult to quantify. However, atrial ejection force, defined as that force exerted by the left atrium to accelerate blood into the left ventricle during atrial systole, can be assessed noninvasively by combined two-dimensional imaging and Doppler echocardiography. This index of atrial function, based on classic newtonian mechanics, provides a physiologic assessment of atrial systolic function. METHODS: To evaluate the usefulness of atrial ejection force, we studied the return of left atrial ejection force in 29 patients after elective cardioversion for atrial fibrillation. Transmitral Doppler inflow patterns at rest were assessed immediately after cardioversion and at 24 h, 1 week, 1 month and > 3 months later. A healthy adult group (n = 10) served as control subjects. RESULTS: After successful cardioversion, atrial ejection force was significantly depressed compared with that in the control group (5.2 +/- 6.8 vs. 16.3 +/- 4.7 kdynes; p < 0.0001). Over successive weeks, atrial ejection force improved in the subgroup of patients who remained in sinus rhythm (n = 18), whereas no improvement was seen during the period of maintained sinus rhythm in the patients with subsequent reversion to atrial fibrillation (n = 11). CONCLUSIONS: Atrial ejection force provides a physiologic assessment of atrial systolic function and is a potentially useful index for assessing atrial contribution to diastolic performance. In patients who successfully underwent cardioversion from atrial fibrillation, atrial ejection force improved over several weeks only in the subgroup in which sinus rhythm was maintained.

Adult↗
PubMed1980

[Influence of left atrial pressure on left ventricular function after extracorporeal circulation (author's transl)].

In 10 patients with coronary heart disease, in 9 with advanced mitral and in 11 with aortic valve disease left ventricular function curves were constructed by volume loading immediately after cardiopulmonary bypass. After aortocoronary bypass surgery an approximately linear correlation between both cardiac index and stroke volume index and left ventricular filling pressure was demonstrated. After aortic and mitral valve replacement increase in left ventricular filling pressure above 15 mm Hg failed to result in significant increase in CI and SVI. Apparently, volume loading has limited effects in regulating left ventricular function in advanced aortic and mitral valve disease.

Atrial Function↗
PubMed1979

Effect of therapeutic-dose irradiation on left ventricular function in conscious dogs.

Every week, 8 conscious, chronically instrumented dogs underwent left ventricular (LV) function studies before, during, and after cardiac irradiation with cobalt 60 (myocardial dose of 5,000 rads at 200 rads per day through a 5 X 5 cm port). During the weekly LV function studies, left atrial pressures were raised by rapid infusion of balanced saline solution. Heart rate, aortic pressures, left and right atrial pressures, LV pressure, left ventricular end-diastolic pressure (LVEDP), and maximum rate of rise of LV pressure were recorded. Electrocardiograms were made. Cardiac outputs were obtained by thermodilution. Stroke volume, LV stroke work, and LV minute work were calculated. LV function curves were constructed each week. All dogs lost weight and became irritable after approximately 800 rads. The electrocardiograms showed signs of myocardial injury after 1,200 rads. All variables were slightly depressed during the first 8 weeks following irradiation. At the eleventh week, both left atrial pressure and LVEDP increased significantly and LV function declined. There was also clinical evidence of LV failure at rest and after volume loading. This study documents that external cardiac irradiation, in a therapeutic dose and schedule range, causes depression of LV function. These functional changes were partially reversed when the follow-up study was continued to six months after irradiation.

Animals↗
PubMed2001

Compensatory responses of left atrial conduit flow to atrial fibrillation with acute myocardial infarction in a canine model.

The aim of this study was to examine the interaction of acute atrial fibrillation (Af) and acute myocardial infarction (AMI) on left atrial (LA) and left ventricular (LV) filling in atrioventricular (A-V) sequential paced, open chest, anesthetized dogs. Left atrial conduit function was determined from pulmonary venous flow (PVF) and detailed analysis of early diastolic flow with the use of micromanometers and transmitral Doppler echocardiography. We studied 8 dogs with regular ventricular rates to avoid the confounding effect of ventricular arrhythmia in Af. In the control stage, Af increased the diastolic PVF volume to the left atrium compared with that during regular A-V pacing (from 0.58 +/- 0.11 mL/beat to 0.70 +/- 0.13 mL/beat, P <.05), as a compensatory response to the impaired systolic PVF volume (from 0.56 +/- 0.12 mL/beat to 0.41 +/- 0.11 mL/beat, P <.05). As a result, cardiac output was maintained. However, in the AMI stage, Af decreased cardiac output (from 0.95 +/- 0.32 L/min to 0.80 +/- 0.23 L/min, P <.05 versus AMI with A-V pacing), and decreased diastolic PVF volume (from 0.46 +/- 0.13 mL/beat to 0.33 +/- 0.14 mL/beat, P <.05 versus AMI with A-V pacing). These changes were associated with a prolonged LV isovolumic pressure decay rate. Our study demonstrates that Af does not affect cardiac output in the setting of normal LV function at a controlled ventricular rate because enhanced LA conduit flow compensates for impaired LA reservoir function. In contrast, in the setting of AMI, the compensatory response to Af is attenuated because of abnormal LV relaxation, resulting in a decrease in cardiac output.

Animals↗
PubMed1995

Effects of volume loading on pulmonary venous flow pattern in dogs with normal left ventricular function.

The effects of altered loading conditions on the pattern of pulmonary venous flow are poorly understood. The authors investigated such effects, therefore, by using volume loading in 6 open-chest dogs. The pulmonary venous flow volume rate curve was obtained with a transit-time ultrasonic flowmeter at a fixed heart rate. Measurements were performed in the control and several states during the intravenous infusion of dextran. The influences of volume loading on hemodynamic and pulmonary venous flow variables were compared between the control state and three interventional states in which mean left atrial pressure was approximately 1, 2, and 3 mm Hg above the control value. The systolic flow volume (SI), which corresponds to left atrial reservoir volume, significantly increased, but the early diastolic flow volume (DI), which corresponds to left atrial conduit volume, did not show significant change with volume loading. The flow volume during left atrial contraction significantly increased with volume loading. The flow volume during one cardiac cycle (PVF) significantly increased with volume loading. Approximately 73% of increased PVF was distributed to the systolic flow. The rest was distributed to the early diastolic flow (14%) and to the flow during left atrial contraction (12%). The change in the ratio of SI/DI significantly and positively correlated with the change in mean left atrial pressure (r = 0.87, P < 0.001). These findings indicate that increased pulmonary venous flow induced by volume loading in dogs with normal left ventricular function is mainly distributed to the left atrial reservoir volume.

Animals↗
PubMed2000

Immediate effect of balloon valvuloplasty on hemostatic changes in mitral stenosis.

This study was conducted to assess right and left atrial hemostatic function in patients with mitral stenosis (MS) and to investigate the immediate effect of balloon mitral valvuloplasty (BMV) on hemostatic function. BMV was performed in 28 patients with MS (age 29 +/- 8 years) who had sinus rhythm and no left atrial (LA) thrombus. Right and left atrial biochemical markers of platelet activity (platelet factor 4 [PF4] and B thromboglobulin [BTG]), coagulation (thrombin-antithrombin III complex [TAT]), and fibrinolytic activity (D-dimer) were measured before and 30 minutes after BMV. Right atrial levels of these markers were also measured in 20 control subjects. Compared with control subjects, patients with MS had higher right atrial levels of PF4 (30 +/- 15 vs 5 +/- 2 IU/ml), BTG (231 +/- 53 vs 30 +/- 8 IU/ml), TAT (7 +/- 4 vs 2 +/- 0.3 microg/L), and D-dimer (380 +/- 145 vs 160 +/- 35 ng/ml, p < 0.0001 in all). TAT levels were higher in the left atrium than in the right atrium of patients before BMV (8 +/- 4 vs 7 +/- 4 microg/L, p < 0.0001). BMV was successful (final mitral valve area > or = 1.5 cm2 and > or = 50% increase of the initial valve area) in all patients. There was a significant reduction of LA levels of PF4 (35 +/- 8 to 26 +/- 9 IU/ml, p < 0.0001), BTG (225 +/- 41 to 196 +/- 28 IU/ml, p < 0.001), and TAT (10 +/- 5 to 7 +/- 1 microg/L, p < 0.05) in the 16 patients with LA pressure < 10 mm Hg after BMV, whereas these markers were not reduced in the 12 patients with left atrial pressure > or = 10 mm Hg after BMV. These data indicate that platelet function, coagulation status, and fibrinolytic activity are increased regionally in the left atrium and in the systemic circulation in patients with MS and sinus rhythm in the absence of LA thrombus. Successful BMV induces a significant reduction of prethrombotic status in patients with low LA pressure after the procedure. Patients with high LA pressure after BMV maintain a high prethrombotic state and may be considered at an increased risk of thromboembolism after the procedure.

Adolescent↗