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PubMed1985

Is atrial function affected by conventional cardioplegic arrest?

Conventional cardioplegic arrest results in persistent atrial electrical and mechanical activity. This activity has been postulated to result in atrial ischemia which can induce postoperative arrhythmias and impair the transport function of the atrium. In this study, the effects of simple cardiopulmonary bypass (CPB) (seven pigs) and conventional cardioplegic arrest (CCA) (seven pigs) on right atrial function were evaluated. Function was assessed in an isolated right atrial preparation with a compliant balloon inserted via the superior vena cava. CCA for 1 hr produced significant deterioration in right atrial function (developed pressure 14.1 +/- 0.7 vs 18.9 +/- 0.8 mm Hg, P less than 0.05, diastolic pressure 10.0 +/- 1 vs 4.5 +/- 1.4 mm Hg, P less than 0.05, dP/dt 134 +/- 25 vs 187 +/- 19 mm Hg/sec, P less than 0.05 at a balloon volume of 20 ml after 1 hr of reperfusion). CPB alone caused no alteration in pressures in the right atrium but was associated with a late decrease in dP/dt (developed pressure 19.3 +/- 1.8 vs 18.9 +/- 0.8 mm Hg, diastolic pressure 4.0 +/- 1.2 vs 4.5 +/- 1.4 mm Hg, dP/dt 148 +/- 18 vs 187 +/- 19, P less than 0.05 at a balloon volume of 20 ml at a time corresponding to 1 hr of reperfusion in the CCA group). These results are consistent with the postulate that conventional techniques of cardioplegic arrest are associated with ischemic dysfunction of the right atrium.

Animals↗
PubMed1998

Left atrial function is unchanged by implantable defibrillator shocks on hearts in sinus rhythm.

Sixteen patients in sinus rhythm at baseline undergoing implantable cardioverter-defibrillator implantation were monitored with transesophageal echocardiography both before and after direct current cardioversion with currents of 15 to 20 J, for any direct current induced atrial dysfunction. We found no change in the indexes of atrial function or appearance of spontaneous echo contrast in the immediate postshock period by intraoperative transesophageal echocardiography.

Atrial Function, Left↗
PubMed1994

Protection of atrial function in hypoxia by high potassium concentration.

1. The effects of high extracellular potassium on hypoxia-induced atrial activity and metabolic charge were studied in isolated rat atria. 2. After hypoxia (30 min), contractile tension strongly decreased and diastolic tension increased, while frequency did not change. Adenine nucleotides and creatine phosphate levels did not change, although a significant increase in lactic acid content was observed. 3. High [K+] mostly countered the hypoxia-induced increase in diastolic tension. Moreover, in the presence of high [K+], the hypoxia-induced increase in lactic acid was not significantly different from normoxic controls. 4. Glibenclamide (0.1 microM), a selective K+ATP channel blocker, did not improve the hypoxia-induced depression of atrial function. 5. The physiopathological role of extracellular potassium during cardiac hypoxia is discussed.

Adenine Nucleotides↗
PubMed1978

[Evaluation of sino-atrial function using the method of extrasystole induced by constant-relative premature impulses. 1. Method and normal results].

Atrial pacemaking under conditions of relative constancy (40 or 50% of the preceding cycle) enables us to calculate the immediate sino-atrial conduction time (retrograde and antegrade) (SACT). 17 patients were chosen for their normal sino-atrial function under spontaneous changes of the sinus cycle (SC). In each case, a significant inverse linear relationship was found between SACT and the corresponding SC. The mean correlation slope was -0.36 in 10 patients with no post-pacing depression (PPD). The slope was greater in 7 patients with a PPD (-0.89); if this depression is taken into account when the SACT is calculated, the slope decreases. In 5 patients, atropine (1 mg I.V. reduced the mean value of SC, and shortened (constant relative value) the SACT. The mechanisms for the spontaneous and induced variations in the sinus output are discussed; it may be that there are substitute pacemakers within the cells of the sino-artrial node, which are affected by variations in sympathetic or parasympathetic activity or by pacing. In clinical practice, automatism and conduction with the sinus node should be interpreted as inter-related functions, both under normal conditions and after vagal block.

Adult↗
PubMed1999

[Correction of morphology and indicators of atrial function using long-term physiologic cardiac pacing in patients with prior chronic atrioventricular dissociation or VVI pacing].

UNLABELLED: In patients with atrioventricular dissociation associated with complete atrioventricular block or reverse synchronization and preservation of the sinus rhythm the atria are mechanically over-burdened by contraction in an inept stage of the cardiac cycle (against a closed atrioventricular valve). Prolonged overburdening leads to dilatation of the atria and a higher incidence of supraventricular arrhythmias incl. atrial fibrillation. The objective of the trial was to assess whether these changes are reversible. METHOD: In 26 patients where atrioventricular dyssynchronization as the only detectable reason of atrial dilatation was eliminated by implantation of sequential atrioventricular stimulation, the authors investigated by echocardiography the dimensions, volumes and ejection fractions of the atria and left ventricle at baseline (A), after 24 hours following implantation (B), after 8 weeks (C), after one year (D). RESULTS: Left atrium: during the first 24 hours diminution in the long axis occurred (AxB: -4.28, p = 0.023), the difference remained significant even after eight weeks (AxC: -6.1, p = 0.050). The ejection fraction was after eight weeks also significantly greater (BxC: +8.29, p = 0.039). Right atrium: within 24 hours the long axis was reduced (AxB: -4.70 p = 0.033), the difference was apparent also after 8 weeks (AxC: -5.60 p = 0.028). Within 8 weeks (AxC) the mean enddiastolic pressure diminished significantly (-11.01, p = 0.032) as well as the endsystolic volume (-9.01, p = 0.018, while the ejection fraction increased (+7.50, p = 0.031). The right ventricular volume during diastole increased between the 8th week and the check-up after one year (+6, -1, +17.77, p = 0.046). Left ventricle: the ejection fraction had a rising trend, after one year a significant difference was found as compared with the baseline value (AxD: +10.20%, p = 0.007) and as compared with the value assessed 8 weeks after implantation (CxD: +9.44%, p = 0.018). The change of the ejection fraction was inversely proportional to the value of the ejection fraction immediately after implantation (r -0.83, p < 0.01). CONCLUSION: The authors provided evidence of the reversibility of the morphological and functional atrial damage and the favourable effect of atrioventricular synchronization on left ventricular function.

Aged↗
PubMed1997

Relationship between atrial function, left ventricular isovolumic relation time, and early filling in dual chamber-paced patients.

This investigation was performed to study atrial systolic function is response to modification of atrioventricular delay in a sample of 36 patients with a DDD pacemaker implanted for complete atrioventricular block. The relation between atrial systolic performance and diastolic-related parameters was also evaluated. Isovolumic relaxation time, early diastolic peak velocity, late (atrial) diastolic peak velocity, atrial filing fraction, and atrial ejection force were recorded at a pacing rate of 70 impulses/min and at atrioventricular delay of 200, 150, and 100 msec. Our data showed that the progressive shortening of atrioventricular delay induced a gradual increase in early peak velocity (median value 46 to 53 to 61.5 cm/sec, respectively, at 200, 150, and 100 msec intervals) and a gradual decrease in isovolumic relaxation time (median 92.6 to 81.5 to 69.7 msec at 200, 150, and 100 msec, respectively), atrial peak velocity (59 to 52 to 44.5 cm/sec at 200, 150, and 100 msec, respectively), atrial filling fraction (50.5% to 40% to 23.5% at 200, 150, and 100 msec, respectively), and atrial ejection force (17.2 to 14.7 to 8.5 kilodynes at 200, 150, and 100 msec, respectively). For every atrioventricular delay value detected, we found a significant correlation between isovolumic relaxation time and early peak velocity with atrial filling fraction and atrial ejection force. In addition, atrial ejection force was related directly to atrial filling fraction at studied atrioventricular delays. The two indexes of atrial systolic performance showed a parallel decrease by shortening the atrioventricular delay, and they can quantify atrial systolic performance equally in sequentially paced patients. Furthermore, our results are in accordance with the hypothesis that the interaction between the effectiveness of active left atrial emptying and isovolumetric relaxation time may play an important role in maintaining an ideal ventricular filling despite changes in atrial systolic function.

Aged↗
PubMed1998

Increasing degrees of left ventricular filling impairment modulate left atrial function in humans.

We sought to investigate the changes in atrial reservoir, pump, and conduit functions that are associated with increasing degrees of left ventricular filling impairment. In 13 patients with an impaired relaxation type of filling and in 15 with restrictive patterns, the left atrial volume curve was constructed combining Doppler and 2-dimensional echocardiography. Nine normal subjects served as controls. Left atrial reservoir (defined as [maximum - minimum atrial volume] minus the amount of blood flow reversal in the pulmonary veins with atrial contraction), pump (defined by the volume of blood that enters the ventricle with atrial contraction), and conduit functions (defined as left ventricular filling volume - [left atrial reservoir plus pump volume]) were computed and each expressed as a percentage of ventricular filling volume. The atrial reservoir function was higher in the impaired relaxation group than in normal subjects (49+/-8% vs 38+/-8%, p <0.01) but markedly lower in the restrictive group (27+/-8%, p <0.05). The reverse was true for conduit function, exaggerated in restrictive group (54+/-12% vs 36+/-11% in normal subjects, p <0.01) but minimized in patients with an impaired relaxation type of filling (14+/-9%, p <0.001). The atrial pump contributed 19+/-6% of ventricular filling volume in restrictives, 26+/-3% in normals (p <0.01), and 38+/-4% (p <0.001) in the impaired relaxation group. We conclude that increased atrial response to early-stage left ventricular filling impairment is characterized by augmented reservoir and pump functions, according to a Starling mechanism, which becomes hardly effective at end-stage ventricular dysfunction when the limits of the atrial preload reserve are reached. At this stage, conduit in the atrium takes precedence.

Adult↗
PubMed1986

Recovery of isolated rat atrial function related to ATP under different anoxic conditions.

Spontaneously beating isolated rat atria were subjected to 1 h of anoxia at 37 degrees C in various cardioplegic solutions. Contraction continued for different times upon initiation of anoxia, depending on the nature of the cardioplegic solution. Two hundred micromolar P1,P5-di(adenosine-5')pentaphosphate (Ap5A) stopped atrial function in less than 30 s of anoxia in contrast to 50 s in the case of Hearse's cardioplegic solution (16 mM MgCl2, 16 mM KCl, 1 mM Procaine), and 20 min in the case of controls. The stopping time was also prolonged from 30 to approximately 50-55 seconds if a lower concentration of Ap5A (100 microM) was used. Function, adenine nucleotides (AN), and phosphocreatine (PCr) were then measured 20 min after reoxygenation. The recovery of both function and AN was most rapid and complete with 200 microM Ap5A (97% recovery in ATP and 100% in function) and least complete in control (50% recovery in ATP and 78% in function). A positive correlation between recovery of ATP, or total adenine nucleotides, and recovery of function was observed in all cases. The higher the level of ATP remaining at the end of 1 h of anoxia and the more recovered after 20 min of reoxygenation, the more complete the recovery of function. The PCr returned to normal or even higher than normal values in all cases, even though function returned only in proportion to ATP. Since PCr is mitochondrial in origin, it appears that loss of a portion of the AN localized at the energy-utilizing sites occurred before serious mitochondrial damage and was responsible for the incomplete postanoxic functional recovery.

Adenine Nucleotides↗
PubMed1998

Echocardiographic assessment of right atrial function in patients with myocardial infarction with reference to obstructive lesions of the coronary arteries.

We assessed the relationship between right atrial (RA) function and obstructive lesions of the coronary arteries in 29 patients with recent or old myocardial infarction (MI). Patients were divided into 3 groups according to the location of obstructions as follows: obstruction at the proximal right coronary artery (segments 1 and 2) (RCA proximal group, n=9); obstruction at the distal RCA (segments 3 and 4) (RCA distal group, n=6); and obstruction at the left anterior descending coronary artery (LCA group, n=14). The RA volume and the fractional change in the RA area during atrial contraction (RA %AC) were evaluated by apical 2-dimensional echocardiography. The right ventricular (RV) end-diastolic pressure (RVEDP) was measured in 4 patients in the RCA proximal group and 4 patients in the LCA group. The ejection fraction of the right ventricle (RVEF) was measured by radionuclide angiography or 2-dimensional echocardiography in 7 patients in the RCA proximal group, 5 patients in the RCA distal group, and 7 patients in the LCA group. The RVEF tended to be lower in the RCA proximal group than in the RCA distal and LCA groups. The RA volume was significantly greater in the RCA proximal group than in the LCA group. The RA %AC was significantly smaller in the RCA proximal group than in the RCA distal and LCA groups. There were no significant differences in the early diastolic RV inflow velocity among groups, but the late diastolic RV inflow velocity was significantly lower in the RCA proximal group than in the RCA distal and LCA groups. There was no significant difference in the RVEDP between the RCA proximal and LCA groups. Thus, RA dysfunction in the RCA proximal group appeared to be due to myocardial damage rather than to afterload mismatch. These findings suggest that RA dysfunction may occur in patients with an inferior MI who have an obstructive lesion of the proximal RCA.

Aged↗
PubMed1999

Effects of pacing-induced and balloon coronary occlusion ischemia on left atrial function in patients with coronary artery disease.

OBJECTIVES: The aim of this study was to compare left atrial (LA) function in 16 patients with distal left anterior descending (LAD) and in 16 patients with proximal left circumflex (LCx) coronary artery stenosis at rest and immediately after pacing-induced tachycardia (LAD-pacing [P] and LCx-P) or coronary occlusion (LAD-CO and LCx-CO). BACKGROUND: During left ventricular (LV) ischemia, compensatory augmentation of LA contraction enhances LV filling and performance. The left atrium is supplied predominantly by branches arising from the LCx. Therefore, we hypothesized that one mechanism for the loss of atrial contraction may be ischemic LA dysfunction. METHODS: Left ventricular and LA pressure-area relations were derived from simultaneous double-tip micromanometer pressure recordings and automatic boundary detection echocardiograms. RESULTS: Immediately after pacing or after coronary occlusion, LV end-diastolic pressure, LV relaxation, LA mean pressure and LV stiffness significantly increased in all patients. However, the area of the A loop of the LA pressure-area relation, representing the LA pump function, significantly decreased in groups LCx-P and LCx-CO (from 14+/-3 to 9+/-2, and from 16+/-4 to 9+/-2 mm Hg.cm2, respectively, p < 0.05), whereas it increased in groups LAD-P and LAD-CO (from 12+/-3 to 54+/-10, and from 16+/-3 to 49+/-8 mm Hg.cm2, respectively, p < 0.001). CONCLUSIONS: In patients with LAD stenosis, LV supply or demand ischemia is associated with enhanced LA pump function. However, in patients with proximal LCx stenosis who develop the same type and degree of ischemia, LA branches might have been affected, rendering the LA ischemic and unable to increase its booster pump function.

Angioplasty, Balloon, Coronary↗
PubMed1990

Left atrial function in acute transient left ventricular ischemia produced during percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery.

Left atrial (LA) function was studied in 32 patients during percutaneous transluminal coronary angioplasty of the proximal left anterior descending artery with a dual micromanometer positioned transseptally in the left atrium and in the left ventricle. In 10 patients LA and left ventricular (LV) cineangiography was performed 30 minutes before percutaneous transluminal coronary angioplasty and 30 seconds after the occlusion of the left anterior descending coronary artery. Thirty seconds after left anterior descending occlusion, LV peak systolic pressure decreased from 135 +/- 12 to 106 +/- 9 mm Hg (p less than 0.05) and LV maximum dP/dt decreased from 1,634 +/- 136 to 1,137 +/- 127 mm Hg/s (p less than 0.01). Simultaneously, LA mean pressure increased from 11 +/- 2 to 29 +/- 1 mm Hg (p 177 +/- 13 to 381 +/- 21 mm Hg (p less than 0.001). There was a difference between LV end-diastolic pressure and LA mean pressure of 1.5 mm Hg at rest and 7.8 mm Hg during ischemia and LA pulse pressure increased from 16 +/- 3 to 26 +/- 3 mm Hg (p less than 0.05) together with increase of LA A and V waves peak pressure. LV stroke volume index decreased from 46 +/- 5 to 43 +/- 3 ml/m2 (difference not significant). The LA maximal volume increased from 18 +/- 2 to 29 +/- 3 ml/m2 (p less than 0.001). LA volume before LA contraction increased from 29 +/- 2 to 54 +/- 3 ml/m2 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Left atrial function as a reliable predictor of exercise capacity in patients with recent myocardial infarction.

STUDY OBJECTIVE: To examine the relation between left atrial (LA) function and exercise performance. DESIGN AND SETTING: Retrospective study at a referral cardiopulmonary exercise laboratory in a university hospital. PATIENTS: Forty-one patients with recent myocardial infarction. INTERVENTIONS: M-mode echocardiography and cardiopulmonary exercise testing combined with radionuclide ventriculography. MEASUREMENTS AND RESULTS: Hemodynamic measurements were obtained at rest and peak exercise. LA fractional shortening at rest was used as an index of global LA function. LA fractional shortening had fair correlations with peak oxygen consumption (r=0.67, p<0.01) and exercise duration (r=0.71, p<0.01). Although there were no significant relations between LA fractional shortening and hemodynamic measurements at rest, LA fractional shortening was positively related to peak cardiac output (r=0.61, p<0.01) and peak stroke volume (r=0.57, p<0.01), and negatively related to peak pulmonary arterial wedge pressure (r=-0.44, p<0.05). In addition, LA fractional shortening correlated significantly with an increase in left ventricular (LV) end-diastolic volume from rest to peak exercise (r=0.48, p<0.02), but did not correlate with the changes in ejection fraction and end-systolic volume during exercise. An increase in LV end-diastolic volume during exercise was significantly related to peak oxygen consumption (r=0.46, p<0.02), peak cardiac output (r=0.60, p<0.01), and peak stroke volume (r=0.53, p<0.01), whereas the changes in ejection fraction and end-systolic volume during exercise were not related to these indexes. CONCLUSIONS: Exercise capacity and LV performance during exercise were mainly dependent on LV diastolic filling rather than systolic contraction during exercise. LA fractional shortening at rest reflected LV diastolic filling during exercise and, therefore, predicted cardiac output and stroke volume responses to exercise and exercise capacity in patients with recent myocardial infarction.

Adult↗
PubMed1981

Measurement of normal left atrial function with gated radionuclide angiography.

A method is described for measuring relative left atrial volume changes with gated radionuclide angiography, using an approximate computer-generated functional image to locate the atrial region of interest. M mode echocardiographic measurements of left atrial and left ventricular distances from the chest wall allowed calculation of a correction factor for the differential attenuation of atrial and ventricular photons. Background-corrected left atrial time-activity curves obtained from normal subjects exhibited excellent temporal resolution and were used to identify and quantitate the reservoir and contractile phases of left atrial volume change. In 20 normal subjects, the mean (+/- standard deviation) value for left atrial fractional emptying was 0.39 +/- 0.07. Expressed as fractions of the left ventricular stroke volume, mean values of the specific phases of atrial volume change were (1) reservoir volume 0.25 +/- 0.09, (2) contractile volume 0.29 +/- 0.10, and (3) conduit volume 0.46 +/- 0.12.

Adult↗
PubMed1998

Effects of balloon mitral valvuloplasty on left atrial function in mitral stenosis as assessed by pressure-area relation.

OBJECTIVES: This study sought to investigate the changes induced on the pressure-area relation of the left atrium in patients with mitral stenosis after percutaneous balloon mitral valvuloplasty. BACKGROUND: Left atrial (LA) function is influenced by changes in LA afterload. The latter is increased in mitral stenosis as a result of increased resistance to blood flow imposed by the stenotic mitral valve. METHODS: We studied the effects of acute alterations of LA afterload induced by retrograde nontransseptal balloon mitral valvuloplasty (RNBMV) on LA function in patients with mitral stenosis. LA pressure-area relations were obtained in 15 patients with mitral stenosis (8 with sinus rhythm, 7 with atrial fibrillation) before and after valvuloplasty, as well as in 15 normal subjects. LA pressure was recorded by a catheter-tipped micromanometer introduced retrogradely into the left atrium while LA area was recorded simultaneously using acoustic quantification. The areas of the A and V loops of the pressure-area relation as well as the LA chamber stiffness constant were calculated. RESULTS: Balloon valvuloplasty resulted in a significant increase in mitral valve area (p < 0.001) and a substantial reduction of the mean transmitral pressure gradient (p < 0.001) and mean LA pressure (p < 0.001). The area of the A loop in patients with sinus rhythm and the area of the V loop in those with atrial fibrillation increased significantly after completion of the procedure (p < 0.001). Furthermore, LA stiffness decreased in both groups. CONCLUSIONS: After RNBMV, there is a significant increase in LA pump function in patients with sinus rhythm, a significant increase in LA reservoir function in patients with atrial fibrillation and a significant reduction in LA stiffness in all patients. Marked alterations of the configuration of the LA pressure-area relation occur immediately after successful RNBMV in patients with mitral stenosis.

Adult↗