[Method of evaluation of the right atrial function following complete right atrial bypass in tricuspid valve stenosis--ejection fraction of the right atrium].
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Atrial Function↗
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Significance of right atrial function during right sided inotropic stimulation of pig hearts in situ.
Cardiac adjustments to inotropic stimulation of the right side of the heart were examined in anaesthetised, open chest pigs by calcium chloride infusion (80 mumol.min-1) into the right coronary artery. At stable haemodynamic conditions and at constant heart rate, right ventricular (RV) pre-ejection segment length increased by 4.6 (2.7-7.2) % (median, 95 % confidence interval) (p less than 0.01), RV end diastolic pressure rose from 5.3 (3.4-7.7) to 6.0 (3.6-8.8) mm Hg (p less than 0.05), and stroke volume rose by 6.8 (4.2-10.8) % (p less than 0.001). When the effect of right atrial contraction on RV filling was excluded by simultaneous pacing of atria and ventricles, the RV pre-ejection segment length no longer increased, and stroke volume rose by only 3.5 (0.1-9.5) % (p less than 0.05) during right side inotropic stimulation. Right atrial inotropic stimulation improves right ventricular filling, and may cause redistribution of blood from the systemic to the pulmonary circulation. This redistribution would raise the pulmonary vascular pressures, and thereby also improve left ventricular filling. The improved right ventricular filling partly accounts for the rise in RV output.
Animals↗
The effects of cardioplegic arrest on right atrial function.
Atrial electrical and mechanical activity persists during cardioplegic arrest. It has been postulated that atrial ischemia may occur and cause deterioration in atrial function. This study was designed to assess the effect of cardioplegic arrest on right atrial function. Twenty-one pigs were placed on cardiopulmonary bypass (CPB), and the right atrium was isolated from the circulation by snaring both venae cavae and incising the coronary sinus. The tricuspid valve was closed through a small right ventriculotomy, and baseline atrial function was assessed using a compliant balloon in the atrium. Fourteen pigs underwent one hour of cardioplegic arrest (7 with cardioplegia alone [CCA group] and 7 with the addition of topical hypothermia [CCA + TH group]) followed by one hour of normothermic reperfusion. Seven other pigs were placed on CPB for the same period of time (CPB group). Atrial electrical and mechanical activity persisted at 45 beats per minute in the CCA group but was virtually abolished in the CCA + TH group. Cardioplegic arrest caused considerable deterioration in right atrial function (developed pressure, 18.9 +/- 0.8 [baseline] versus 14.1 +/- 0.7 mm Hg; p less than 0.05; first derivative of atrial pressure [dP/dt], 187 +/- 19 versus 134 +/- 25 mm Hg per second; p less than 0.05; 60 minutes of reperfusion and balloon volume of 20 ml). It was not affected by topical cooling. Right atrial developed pressure was maintained, but dP/dt was significantly reduced in the CPB group. This study suggests that cardioplegic arrest does not protect the atrium.
Animals↗
Right atrial function in hypertension.
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Atrial Function, Right↗
Right atrial function in hypertensive patients: effects of antihypertensive therapy.
OBJECTIVES: The effects (16 weeks) of oral antihypertensive drugs on right atrial (RA) function were evaluated by two-dimensional and Doppler echocardiography in 64 patients with mild-to-moderate essential hypertension. Thirty-two age- and sex-matched normal subjects served as controls. BACKGROUND: Hypertension alters the diastolic properties of the left ventricle and disturbs the left atrial contractile activities. RA performance may also alter in essential hypertension. METHODS: From the tricuspid flow velocity curves the E/A ratio, the velocity-time integrals (Ei and Ai, respectively) as well as the sum, TTi = Ei + Ai, were measured. RA active contribution (RAAC) was expressed as the ratio RAAC = Ai/TTi. RESULTS: RA-A/E ratio, RA-Ai and RAAC were increased while RA-TTi were decreased in hypertensives compared to controls, P < 0.0001 for all comparisions. After therapy TTi increased (from 13.2 +/- 1.6 to 16.2 +/- 2.0 cm with ramipril, and from 12.9 +/- 1.1 to 14.4 +/- 1.2 cm with amlodipine, P < 0.001) and RAAC decreased (from 0.19 +/- 0.01 to 0.13 +/- 0.01, with ramipril and from 0.19 +/- 0.01 to 0.16 +/- 0.00, with amlodipine P < 0.001) while RA dimensions did not change. the decrease in RAAC was significantly greater with ramipril (P < 0.001) and was significantly influenced by the decrease in left ventricular mass (P < 0.001) and right ventricular relaxation (P < 0.001). CONCLUSIONS: RA function is deteriorated in patients with essential hypertension. The fall in the arterial blood pressure produced by antihypertensive treatment was associated with improved RA performance and reduced left ventricular mass without changes in RA dimensions. The left ventricular mass and the right ventricular relaxation influenced the changes in RA performance.
Adult↗
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↗
A new scintigraphic technique for assessment of right atrial function.
Gated radionuclide imaging with 99mTc-labeled red blood cells was employed to assess changes in right atrial (RA) volume in 17 subjects. Studies were repeated within two hours in five of 12 normal subjects and at two and ten days after infarction in five patients. Time-activity curves were generated for the RA and right ventricle (RV) from variable regions of interest defined by automatic edge detection. The RA time-activity curve exhibited four phases: filling, early emptying, equilibration, and late emptying. Repeated measurements of RA early emptying rates correlated closely in normals (r = 0.93). Early RA emptying and RV filling rates corresponded closely (r = 0.89). In four patients with infarction, the RA emptying rate was slowed on the first study but had normalized by 10 days. In a patient with inferior infarction and suspected RV infarction, the RA emptying rate was depressed and remained so for 10 days. Thus, relative changes in right atrial volume can be assessed reproducibly by a radionuclide technique, which is relatively independent of geometric assumptions. This technique offers great promise as a method to assess atrial function in health and disease.
Adult↗
The effects of streptozotocin-induced diabetes and aldose reductase inhibition with sorbinil, on left and right atrial function in the rat.
Diabetes mellitus is frequently associated with the complications of cardiovascular disease. Activation of the aldose reductase (or polyol) pathway has long been implicated as an underlying factor for the development of many diabetic complications and indeed, treatment with aldose reductase inhibitors has been shown to prevent or reverse many of these diabetic complications. This study examines the effects of 14-day streptozotocin-induced diabetes on alpha1- and beta-adrenoceptor-mediated responses in rat isolated left and right atria. The effects of treatment with the aldose reductase inhibitor (ARI) sorbinil were also studied. A positive inotropic response was observed to both isoprenaline and phenylephrine in left atria. Diabetes of 14 days duration resulted in a supersensitivity of these tissues to the beta-adrenoceptor agonist in comparison with controls, while responses to the alpha1-adrenoceptor agonist were unaltered. Spontaneously beating right atria from diabetic rats was found to have a depressed resting rate compared with control tissues, although positive chronotropic beta-adrenoceptor-mediated responses were not affected by diabetes. Phenylephrine produced alpha1-adrenoceptor-mediated chronotropic responses in right atrial tissues, and these were found to be enhanced in rats with diabetes. Treatment of diabetic rats with the ARI sorbinil was successful in preventing only one of the observed diabetes-induced changes in atrial function, namely the supersensitivity of left atria to isoprenaline. Sorbinil treatment did, however, alter responses of control left and right atria in a manner similar to diabetes. In conclusion, streptozotocin-induced diabetes of 14 days duration was found to cause a number of alterations in the functioning of both left and right atria. ARI treatment with sorbinil failed to prevent all but one of these changes, and in addition altered responses of atria from control rats, having a similar effect to that produced by diabetes. These data suggest that sorbinil may have effects in addition to, and independent of, aldose reductase inhibition in the cardiovascular system.
Aldehyde Reductase↗
[Hemodynamic evaluation of complete right heart bypass surgery for correction of tricuspid atresia - with special reference to postoperative hemodynamic evaluation and involvement of the right atrial function].
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Adolescent↗
Right atrial appendage function in patients with chronic nonvalvular atrial fibrillation.
To assess right atrial appendage (RAA) flow and its possible relationship to left atrial appendage (LAA) flow in chronic nonvalvular atrial fibrillation (AF), transesophageal echocardiography (TEE) was performed in 26 patients with chronic nonvalvular AF (group I). For the purpose of comparison, an additional group of 27 patients with chronic valvular AF due to mitral stenosis (group II) was analyzed. The clinically estimated duration of AF in group I was significantly longer than that of group II (8.7+/-3.4 versus 2.7+/-1.1 years). Although right atrial size and RAA maximal area were larger in group I than those in group II, left atrial size was larger in group II than that in group I. Group II had larger LAA maximal areas than group I, but this difference did not reach statistical significance. The two groups were not different with respect to the RAA or LAA emptying velocities. Significant correlations were observed between echocardiographic parameters of the two atria in patients with nonvalvular AF (r range, 0.4 to 0.7). In contrast, in patients with valvular AF, no correlation was observed between the echocardiographic parameters of the two atria (appendage emptying velocity, r = 0.38, p = 0.051; atrial size, r = -0.03, p = 0.89; maximal appendage area, r = 0.07, p = 0.75, respectively). There were no significant differences in the presence of right and left atrial spontaneous echo contrast and thrombus between the groups. All of the right and left atrial thrombi were confined to their respective appendages and were found in the atria with spontaneous echo contrast. Both RAA and LAA thrombi were present in one patient. In conclusion, our findings suggest that AF could affect both atria equally in nonvalvular AF, in contrast to valvular AF. Therefore, the assessment of RAA function as well as LAA may be important in patients with chronic nonvalvular AF.
Aged↗
[Assessment of right atrial and ventricular function by radionuclide ventriculography using continuous infusion of 81mKr].
The purpose of this study is to assess the right atrial and ventricular function by radionuclide ventriculography using continuous infusion of 81mKr in normal subjects and in patients with heart disease. 1) Reproducibility of RVEF measurement by continuous infusion of 81mKr was good (interobserver; gamma = 0.97, p less than 0.001, n = 20: intraobserver; gamma = 0.97, p less than 0.001, n = 20). This method had a excellent correlation with RVEF of 99mTc first-pass technique (gamma = 0.92, p less than 0.001, n = 20). 2) RVEF was measured in 10 normal volunteers, 76 patients with myocardial infarction (OMI), 20 patients with dilated cardiomyopathy (DCM), 5 patients with arrhythmogenic right ventricular dysplasia (ARVD) and 5 patients with primary pulmonary hypertension (PPH). In OMI and DCM, their RVEF was lower than that of normal volunteers and, in ARVD and PPH, lower than that of OMI and DCM. There was a significant inverse correlation between RVEF, mean pulmonary artery pressure and right ventricular end-diastolic volume index. 3) The effect of the location of right coronary artery (RCA) lesions on RVEF during exercise was also evaluated. Ten normal volunteers and 27 patients with OMI were studied at rest and during exercise. The patients with OMI were divided into two groups: those without proximal RCA lesions (non RCA group, n = 12) and those with proximal RCA lesions (RCA group, n = 15). Although there were no significant increases of RVEF during exercise in both group, the percent change in RVEF was less in RCA group than in non RCA group. These findings suggested that proximal RCA stenosis is a major determinant of exercise RVEF. 4) To assess the right atrial function, right atrial volume curve was measured in 10 normal volunteers, 32 patients with OMI and 4 patients with PPH. The curve was clearly divided into 4 phase; filling phase (312 +/- 40 msec), early ejection phase (276 +/- 53 msec), plateau an index of right atrial reservoir function, was 0.41 +/- 0.05 and Contractile Volume/Stroke Volume (Contr. V/SV), as an index of right atrial pump function, was 0.23 +/- 0.05 in normal volunteers. In OMI and PPH, atrial reservoir function decreased and atrial pump function increased. It was concluded that radionuclide ventriculography using continuous infusion of 81mKr was useful to assess the right heart function.
Atrial Function, Right↗
Left and right atrial transport function after the Maze procedure for atrial fibrillation: an echocardiographic Doppler follow-up study.
OBJECTIVES: We evaluated atrial transport function after the Maze procedure in long-term follow-up and compared left and right atrial function in Maze patients with that of healthy age-matched controls using echo Doppler techniques. BACKGROUND: The Maze procedure is designed to eliminate atrial fibrillation, restore normal sinus rhythm, and preserve atrial contraction. Initial data indicate that atrial transport function is restored in most patients undergoing the Maze procedure. The long-term echo Doppler evaluation of patients after the Maze procedure has not been well described. METHODS: We performed pulsed-wave Doppler and two-dimensional echocardiographic studies on 31 patients (24 men, mean age 53.8 years) who underwent the Maze procedure and who had a follow-up study greater than 3 months (mean 16.5 months) after the procedure. Measurements included peak left ventricular and right ventricular inflow A-wave velocity, maximum and minimum left atrial and right atrial areas, and fractional area change of the left and right atria. Results were compared with those obtained from 15 age-matched control subjects (11 men, mean age 53.8 years). RESULTS: Twenty-two patients (71%) had left atrial function shown by the presence of left ventricular inflow A-wave, and 25 patients (81%) had right atrial function shown by the presence of right ventricular inflow A-wave on Doppler echocardiography. The left ventricular inflow A-wave velocity was significantly lower than that of age-matched controls (37.5 +/- 15.5 versus 61.0 +/- 13.9 cm/sec; p < 0.001), whereas the right ventricular inflow A-wave velocity did not significantly differ between patients and control subjects (35.4 +/- 9.9 versus 35.3 +/- 4.9 cm/sec; p = Not significant). Although left and right atrial areas decreased significantly after the procedure, there was no significant change in the fractional area change which was smaller in Maze patients than control individuals. CONCLUSIONS: (1) In long-term follow-up of 16.5 months after the Maze procedure, left atrial systolic function was preserved in 71% of our patients and right atrial systolic function was preserved in 81%; (2) the left ventricular inflow peak A-wave velocity after Maze is considerably less than that in age-matched controls; and (3) left and right atrial sizes decreased after the procedure with no change in the fractional area change. These findings suggest that the Maze procedure is effective in restoring atrial function in the majority of patients; however, restored function is less than in control individuals.
Adult↗
Right Atrial Thrombi and Depressed Right Atrial Appendage Function After Cardioversion of Atrial Fibrillation.
BACKGROUND: It has been shown that cardioversion of atrial fibrillation may result in left atrial chamber and appendage dysfunction and cause new thrombi in the left atrium. The aim of this prospective study was to investigate right atrial appendage function and assess the incidence of new right atrial thrombi after electrical cardioversion. METHODS: Transthoracic echocardiography was performed in 25 patients 4 h before and at 24 h and 7 days after electrical cardioversion to determine right and left atrial mechanical function (internal atrial defibrillation, n = 16; external electrical cardioversion, n = 9), as assessed by peak A wave velocities derived from the transtricuspid and transmitral velocity profiles. In addition, transesophageal echocardiography was performed 4 h before and 24 h after cardioversion to evaluate postcardioversion thrombus formation in the right and left atrial chambers and to assess right and left atrial appendage function. The degree of spontaneous echo contrast was noted, and peak emptying velocities of the appendages were measured before and after cardioversion. RESULTS: Peak emptying velocities of both the right atrial appendage (mean +/- SD, 0.23 +/- 0.1 vs 0.32 +/- 0.11 m/sec; P = 0.02) and the left atrial appendage (0.3 +/- 0.15 vs 0.4 +/- 0.15 m/sec; P = 0.01) were significantly lower 24 h after cardioversion compared with 4 h before cardioversion, respectively. The degree of spontaneous echo contrast increased in the left atrium after cardioversion from 1.0 +/- 1.2 to 1.9 +/- 2.1 (P = 0.02), and in the right atrium, it increased from 0.8 +/- 1.1 to 1.2 +/- 1.1 (P = 0.1) after cardioversion. Peak A wave transtricuspid velocity increased from 0.26 +/- 0.05 m/sec at 24 h to 0.38 +/- 0.06 m/sec (P = 0.001) after 7 days; respective values for transmitral peak A wave velocity were 0.39 +/- 0.15 and 0.54 +/- 0.16 m/sec (P = 0.009). No thrombi were found in either the right or left atrium before cardioversion. In two patients, new thrombi in the right atrium were detected 24 h after internal atrial defibrillation. Thrombi were located at the superior rim of the fossa ovalis in both patients with patent foramen ovale. Another patient had developed a thrombus in the left atrial appendage. CONCLUSIONS: Electrical cardioversion may not only cause left atrial chamber and appendage dysfunction and left atrial thrombi but also lead to depressed right atrial appendage function and the generation of new thrombi in the body of the right atrium.
Journal Article↗
Relation of mean right atrial pressure to echocardiographic and Doppler parameters of right atrial and right ventricular function.
BACKGROUND: A paucity of data exists as to the relation of mean right atrial pressure (RAP) to Doppler parameters of right atrial and ventricular filling. Furthermore, whether echocardiographic parameters of right atrial and right ventricular function and inferior vena cava improve the relation of Doppler filling dynamics with RAP has not been explored. METHODS AND RESULTS: Doppler and echocardiographic studies were performed simultaneously with measurements of mean RAP in consecutive patients who either had a central venous catheter in the Intensive Care Unit or underwent catheterization of the right side of the heart. The initial population consisted of 35 patients with a mean age (+/-SD) of 60+/-15 years; 34% were on mechanical ventilation. Mean RAP averaged 9+/-5.7 mm Hg (range, 2 to 28 mm Hg). Among tricuspid inflow parameters, the strongest relation with RAP was observed with the ratio of early to late velocity (r=.66). For hepatic venous flow, systolic filling wave indexes had the best relation with atrial pressure, the highest being for systolic filling fraction (r=-.86). Weaker relations were noted with the use of right atrial volumes, right ventricular function, and inferior vena caval diameters. The addition of any of these variables did not improve the relation of systolic filling fraction with RAP. The regression equation (RAP=21.6-24 systolic filling fraction) was tested prospectively in the estimation of atrial pressure 50 patients. The correlation coefficient was .89 in the prospective group and .88 in the total group of 85 patients. The mean difference between predicted and actual pressures in the whole population was -0.2+/-2.6 mm Hg. The sensitivity and specificity for mean RAP>8 mm Hg were 86% and 92%, respectively. CONCLUSIONS: Among echocardiographic and Doppler parameters of right atrial and right ventricular function, hepatic venous flow dynamics relate best to mean atrial pressure and can be used clinically to estimate mean RAP.
Adult↗
Right atrial ischemia exacerbates hemodynamic compromise associated with experimental right ventricular dysfunction.
To determine the importance of right atrial function with acute right ventricular dysfunction, sequential right ventricular and right atrial ischemia were induced in 15 dogs. Right ventricular ischemia resulted in right ventricular free wall dyskinesia, right ventricular dilation by ultrasound, elevated right ventricular filling pressure and paradoxic septal motion. There were decrements in right ventricular systolic pressure (28.9 +/- 5.5 to 25.5 +/- 4.6 mm Hg) (p less than 0.05 for these and all subsequent values) and stroke work (5.66 +/- 0.94 to 2.66 +/- 0.62 g.m/m2), resulting in reductions in left ventricular preload, systolic pressure (123 +/- 11 to 97 +/- 12 mm Hg) and stroke volume (24.2 +/- 4.3 to 19.1 +/- 5.2 ml). Right atrial contractility was augmented, as indicated by increases in peak A wave amplitude (ratio of peak A wave to mean right atrial pressure 1.22 +/- 0.02 to 1.46 +/- 0.3) and right atrial stroke work (0.11 +/- 0.02 to 0.25 +/- 0.05 g.m/m2). Right atrial ischemia depressed right atrial contraction, as indicated by decreased A wave amplitude (ratio of peak A wave to mean right atrial pressure 1.46 +/- 0.3 to 1.04 +/- 0.2) and stroke work (0.25 +/- 0.05 to 0.04 +/- 0.01 g.m/m2).(ABSTRACT TRUNCATED AT 250 WORDS)
Analysis of Variance↗
Role of the simultaneous sequential strategy for failed acute sinus restoration after modified left maze procedure for persistent atrial fibrillation with concomitant mitral surgery.
BACKGROUND: We assessed whether the simultaneous sequential strategy could (1) achieve additional sinus restoration for those patients who were not in sinus rhythm while coming off bypass after modified left maze procedure and (2) attain the same long-term success rates as the bi-atrial maze procedure in patients with persistent atrial fibrillation (AF) and mitral valve disease. MATERIALS AND METHODS: Twenty-seven consecutive patients - ten men and 17 women with a mean age of 52 +/- 13 years, all with persistent AF and mitral valve disease - underwent the modified maze procedure with the simultaneous sequential strategy. In the first phase, the modified left atrial maze operation was carried out with concomitant valvular surgery; the right side maze operation was subsequently carried out as a second phase of the sequential strategy only if AF re-appeared following the spontaneous restoration of heart beats during the operation. RESULTS: Twenty patients (74.1%) underwent the left atrial maze procedure only, and seven patients (25.9%) required the subsequent right atrial maze procedure as part of the sequential strategy. At a mean follow-up of 15.1 +/- 7.7 months, six of the 27 patients (22.2%) who underwent additional right atrial maze procedure had restored sinus rhythm. At a mean follow-up of 17.8 +/- 7.3 months, 24 of the 27 patients (88.9%) had restored sinus rhythm and 22 patients (81.5%) had restored bi-atrial transport function (right atrial filling fraction: 40.8 +/- 11.7%; left atrial filling fraction: 22.9 +/- 8.1%) after application of the sequential strategy. CONCLUSIONS: Compared with modified left atrial maze procedure, the application of the simultaneous sequential strategy successfully restored sinus rhythm in an additional 22.2% of patients with persistent AF. The overall sinus conversion rate of 88.9% was comparable with that of the standard bi-atrial maze procedure.
Adult↗
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↗
[Modified Fontan procedure, is the right atrial pump function necessary or not? Experimental approach using simulation model].
The effect of pulsatile pulmonary flow and the characteristics of pulmonary arterial pressure (PAP) trace were examined using a model simulating the right heart following the modified Fontan procedure. An inlet overflow tank (preload), valveless axial pulsatile pump, Windkessel model (afterload), and an outlet overflow tank (left atrium) were connected in series. Standard conditions were: flow 2.00 l/m, with 12 mmHg preload, 3.0 wood units resistance and left atrial pressure at 6 mmHg. The pump rate was set at 80 bpm. Simulated PAP and pulmonary flow (PF) waves produced by this model closely resembled those obtained from patients who had undergone the modified Fontan procedure. Parameters except preload were fixed and changes in PF were examined at varying preload of 8, 12, 15 and 17 mmHg. At the various preload levels, PF increased to values greater than the PF for the same conditions in the non-pulsatile state. With a preload value of 8 mmHg, PF increased from 1.10 l/m (non-pulsatile) to a maximum of 1.55 l/m at a peak PAP of 14 mmHg. With a preload of 12 mmHg, the PF increased from 2.00 l/m (non-pulsatile) to 2.65 l/m at 19 mmHg peak PAP. A preload of 15 mmHg resulted in an increase in PF from 2.65 l/m (non-pulsatile) to 3.30 l/m at 22 mmHg peak PAP, and when the preload was 17 mmHg the PF increased from 3.15 l/m (non-pulsatile) to 3.80 l/m at 25 mmHg peak PAP. The afterload of this model was fixed so the increase in PF with pulsation suggests a decrease in resistance.(ABSTRACT TRUNCATED AT 250 WORDS)
Atrial Function, Right↗