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PubMed1979

Multiple gated cardiac blood pool imaging for left ventricular ejection fraction: validation of the technique and assessment of variability.

The intrinsic variability and accuracy of left ventricular ejection fraction determined by multiple gated cardiac blood pool imaging was evaluated in 83 patients. Ejection fraction by gated studies correlated well with data from first pass radionuclide angiocardiography (r = 0.94) and from contrast angiography (r = 0.84). Intra- and interobserver variabilities of absolute ejection fraction were minimal (mean +/- standard deviation 1.4 +/- 1.2 and 1.6 +/- 1.5 percent, respectively) and were not different for normal (ejection fraction 55 percent or greater) and abnormal patients. Ejection fraction was determined twice in 70 patients: on the same day at intervals separated by 1 to 2 hours (41 patients) and on 2 different days (29 patients). Ejection fraction ranged from 18 to 91 percent and was normal in 37 patients. There was no difference in mean serial variabilities of absolute ejection fraction for all repeat studies performed on the same and separate days (3.3 +/- 3.1 versus 4.3 +/- 3.1 percent (not significantly different). The mean variability of absolute ejection fraction for repeat studies in normal patients was significantly greater than in abnormal patients (5.4 +/- 4.4 versus 2.1 +/- 2.0 percent, P less than 0.01). The incidence rate of absolute interstudy changes of 5 percent or more was significantly higher in normal than in abnormal patients (P less than 0.01). This differential variability should be considered in interpreting sequential changes in left ventricular ejection fraction. To be attributed to nonrandom physiologic alterations, the absolute change in ejection fraction should be 10 percent or more in normal patients and 5 percent or more in abnormal patients.

Angiocardiography↗
PubMed1989

Resection of abdominal aortic aneurysm in patients with low ejection fractions.

The perioperative and long-term survival of patients who undergo resection of abdominal aortic aneurysm is often determined by coexisting cardiac disease. This study evaluates the influence of left ventricular ejection fraction on both perioperative and long-term morbidity and mortality. Preoperative ejection fraction was measured in 104 of 208 patients undergoing elective abdominal aortic aneurysm resection. Nineteen patients were found to have ejection fractions less than 0.35, and this group was compared to 85 patients with ejection fractions greater than 0.35. The two groups did not differ significantly in terms of age, sex, preoperative renal function, or smoking status. The groups were significantly different with respect to the prevalence of prior myocardial infarction (79% of the low ejection fraction group vs 31% of the high ejection fraction group) and symptoms equivalent to New York Heart Association class II or greater (47% of the low ejection fraction group vs 24% of the high ejection fraction group) but not prior myocardial revascularization procedure (42% of the low ejection fraction group vs 31% of the high ejection fraction group). Surgical factors including aneurysm size, duration of aortic cross-clamping, and extent of arterial replacement did not differ significantly between the two groups. The perioperative mortality was not significantly different (low ejection fraction, 5%; high ejection fraction, 2%). The cumulative life-table survival of the two groups was not statistically different. Two patients in the low ejection fraction group died in the follow-up period, yielding a 4-year actuarial survival of 0.74. This is compared to 10 deaths and actuarial survival of 0.63 (p = NS) in the high ejection fraction group. We conclude that patients should not be denied aneurysm resection solely on the basis of left ventricular ejection fraction.

Aged↗
PubMed1981

Left ventricular ejection fraction calculated from volumes and areas: underestimation by area method.

The ejection fraction is one of the most widely used measurements of left ventricular systolic function. Angiographic measurement of ejection fraction is based on determination of roentgenographic magnification and calculation of end-diastolic and end-systolic volumes, assuming a prolated ellipse. Because it is simple and radiographic magnification may not have been determined, some laboratories have obtained an "ejection fraction" by comparison of end-diastolic and end-systolic areas. A comparison of the two methods was made using ventriculograms of 538 patients from three cardiac catheterization laboratories. The area method of ejection fraction calculation consistently underestimates ejection fraction from left ventricular volumes. A regression equation was derived that allows adjustment of the ejection fraction obtained from areas to that from volumes.

Blood Volume Determination↗
PubMed2002

Consistency of echocardiographic ejection fraction: variation and 'drift' by interpreter and practice site.

AIMS: Visual analysis of ejection fraction by echocardiography (echo) is commonly performed, but little data exists regarding consistency among interpreters. We postulate that an active echo group evolves a standard to which interpreters cluster, with variation or 'drift' occurring at satellite sites distant from the main practice centre. Assuming that echo ejection fraction follows a normal distribution, average ejection fraction for high volume readers should be similar. METHODS AND RESULTS: From May 1997 to June 1999, 8187 echoes were read by 16 (average 512) readers of a single practice at several sites. Composite and individual ejection fraction (visual estimate) means and standard deviations were compared. Composite ejection fraction was 54.17+/-11.35. Mean ejection fraction varied significantly overall among readers (P<0.0001) with 37 comparisons between individual readers being significantly different (P<0.05). However, analysis suggested that these individual differences involved only five readers, four of whom practised at satellite sites. If these five readers were excluded, no significant individual differences were seen (n=6202). If only the four satellite readers were excluded, just four significant individual differences were seen (n=6915). CONCLUSIONS: (1) Within a busy single practice site, mean echo ejection fraction is very similar, suggesting a self-evolved practice standard that is consistently adhered to. (2) 'Drift' or variability is seen at smaller satellite sites, perhaps due to less exposure to the echo interpretations of others. (3) This type of analysis may provide a useful quality assurance tool for echo laboratories.

Cardiology↗
PubMed1990

Comparison with radionuclide angiography of two new geometric and four nongeometric models for echocardiographic estimation of left ventricular ejection fraction using segmental wall motion scoring.

Two new echocardiographic methods for estimating left ventricular ejection fraction, both based on segmental wall motion scoring on a continuous scale, were developed and compared to radionuclide angiography in 50 patients. The first method used a geometric model in which the ventricle was represented by a tubular base section joined to a hemielliptical apex section, each containing 4 quadrants. Contraction was scored visually in 12 regions of the ventricle. The 12 scores were converted to dimensional shortenings, which were then used to calculate separate ejection fractions for each of the 8 quadrants. These 8 values were averaged to obtain the global ejection fraction. Assuming an elliptical end-systolic cross-section shape for each quadrant, the correlation between the echocardiographic and radionuclide ejection fractions was 0.917 with a regression slope of 0.93 and an intercept of 1.5. Results were identical assuming circular end-systolic quadrant shapes. The second approach used a linear combination of the mean wall motion score at the base, midleft ventricle and apex to predict ejection fraction. Coefficients for the 3 mean scores were optimized by least squares best fit with radionuclide ejection fraction in all 50 patients. The simplest linear model showed a correlation of 0.90 between the echocardiographic and radionuclide ejection fraction but underestimated low, and overestimated high, ejection fractions. However, these systematic errors could be removed by regression, which added a constant term of 8.1 and a slope factor of 0.87 to the linear model, improving the correlation with radionuclide ejection fraction to 0.91.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[Analysis of factors influencing the accuracy of ejection fraction measurement based on the thermal washout technic--investigation in a model heart].

Evaluation of ejection fraction and ventricular volume is more difficult in the right side of the heart than in the left side. Thermal washout method in the right ventricle with the aid of a rapid response thermistor made it possible in the clinical practice, but its accuracy is uncertain. We attempted to elucidate what factors could influence the accuracy of the measurement of the right ventricular ejection fractions in a model circuit and artificial heart equipped with two one-way valves. Findings are as follow: 1) By ventricular injection of the cold water it is possible to evaluate the ejection fractions more accurately than by atrial injection. The latter technique measured the ejection fraction 8.4% lower than the actual values. 2) The first ejection fraction measured will be the most accurate among the serially obtained ejection fractions using a thermal washout curve. 3) When the ejection fraction is high, the ejection fractions calculated from the later part of a thermal washout curve will be falsely low. 4) When the cold water is injected through the catheter running in the circuit, the effect of the catheter cooling could not be neglected and ejection fraction will be measured falsely low. The temperature change is so small in the later part of the descending limb of the thermal washout curve, that the effect of catheter cooling and ventricular cooling will be exaggerated and the calculation of the temperature change will be measured falsely high. This seems to be the cause of our findings in this research.(ABSTRACT TRUNCATED AT 250 WORDS)

Hot Temperature↗
PubMed1998

Semi-automatic segmentation of gated blood pool emission tomographic images by watersheds:application to the determination of right and left ejection fractions.

Tomographic multi-gated blood pool scintigraphy (TMUGA) is a widely available method which permits simultaneous assessment of right and left ventricular ejection fractions. However, the widespread clinical use of this technique is impeded by the lack of segmentation methods dedicated to an automatic analysis of ventricular activities. In this study we evaluated how a watershed algorithm succeeds in providing semi-automatic segmentation of ventricular activities in order to measure right and left ejection fractions by TMUGA. The left ejection fractions of 30 patients were evaluated both with TMUGA and with planar multi-gated blood pool scintigraphy (PMUGA). Likewise, the right ejection fractions of 25 patients were evaluated with first-pass scintigraphy (FP) and with TMUGA. The watershed algorithm was applied to the reconstructed slices in order to group together the voxels whose activity came from one specific cardiac cavity. First, the results of the watershed algorithm were compared with manual drawing around left and right ventricles. Left ejection fractions evaluated by TMUGA with the watershed procedure were not significantly different (p=0. 30) from manual outlines whereas a small but significant difference was found for right ejection fractions (p=0.004). Then right and left ejection fractions evaluated by TMUGA (with the semi-automatic segmentation procedure) were compared with the results obtained by FP or PMUGA. Left ventricular ejection fractions evaluated by TMUGA showed an excellent correlation with those evaluated by PMUGA (r=0. 93; SEE=5.93%; slope=0.99; intercept = 4.17%). The measurements of these ejection fractions were significantly higher with TMUGA than with PMUGA (P<0.01). The interoperator variability for the measurement of left ejection fractions by TMUGA was 4.6%. Right ventricular ejection fractions evaluated by TMUGA showed a good correlation with those evaluated by FP (r = 0.81; SEE = 6.68%; slope = 1.00; intercept = 0.85%) and were not significantly different (P = 0.42). The interoperator variability with TMUGA was 6.7% for the right ventricle. Thus, the watershed algorithm proposed is an efficient segmentation tool for the semi-automatic analysis of right and left ventricular ejection fractions by TMUGA. Further studies are necessary to check whether this procedure can be used to evaluate ventricular volumes and cardiac outflow.

Algorithms↗
PubMedDate not supplied

Determination of right ventricular ejection fraction by two-dimensional echocardiographic single plane subtraction method.

Right ventricular ejection fraction is a useful measurement for evaluating right ventricular function in various states, including coronary artery disease, chronic obstructive pulmonary disease, and both congenital and valvular heart diseases. The right ventricular geometry has made it difficult to evaluate right ventricular ejection fraction by simple echocardiographic methods. In this study 36 consecutive patients were examined by two-dimensional echocardiography within 4 hours of radionuclide-determined right ventricular ejection fraction to test a simplified method for calculating right ventricular ejection fraction by two-dimensional echocardiography. Echocardiographic measurements were independently determined in the subcostal and apical four-chamber views. Correlation with first pass radionuclide right ventricular ejection fraction was r = 0.89 and 0.84. Right ventricular ejection fraction could be calculated from one of two views in 92% of patients studied. This technique for determination of right ventricular ejection fraction offers a simple noninvasive method of evaluating right ventricular function.

Adolescent↗
PubMed1991

Prognostic significance of right ventricular ejection fraction following inferior myocardial infarction.

The prognostic significance of right ventricular ejection fraction, measured by radionuclide ventriculography, was assessed in 168 consecutive patients with inferior myocardial infarction. Right ventricular ejection fraction was 0.40 or less in 35 patients. Over a follow-up period of 40 months, there were 15 deaths in the total group of 168 patients, eight (23%) in the 35 with right ventricular ejection fraction of 0.40 or less, and seven (5%) in the remainder of the group. The one year survival of patients with right ventricular impairment (84 +/- 6%) was significantly worse (P less than 0.01) than those with a right ventricular ejection fraction over 0.40 (95 +/- 2%). A multivariate Cox model analysis showed age (P less than 0.001), left ventricular ejection fraction (P less than 0.01), and right ventricular ejection fraction (P less than 0.03) to be independent predictors of survival. Impaired right ventricular function is an adverse prognostic factor in patients with inferior infarction, particularly in those with impaired left ventricular function.

Female↗
PubMed1992

Value and limitations of transesophageal echocardiography in determination of left ventricular volumes and ejection fraction.

Several formulas exist for estimating left ventricular volumes and ejection fraction using conventional two-dimensional echocardiography from transthoracic views. Transesophageal imaging provides superior resolution of endocardial borders but employs slightly different scan planes. The estimation of left ventricular volumes by transesophageal echocardiography has not been validated in human patients. Therefore, the purpose of this study was to compare left ventricular volumes and ejection fraction derived from transesophageal short-axis and four-chamber images with similar variables obtained from ventriculography. End-diastolic and end-systolic volumes and ejection fraction were calculated using modified Simpson's rule, area-length and diameter-length models in 36 patients undergoing left ventriculography. Measurements of left ventricular length were obtained from the transesophageal four-chamber view and areas and diameters were taken from short-axis scans at the mitral valve, papillary muscle and apex levels. Data from transesophageal echocardiographic calculations were compared with end-diastolic volume (mean 172 +/- 90 ml), end-systolic volume (mean 91 +/- 74 ml) and ejection fraction (mean 52 +/- 15%) from cineventriculography using linear regression analysis. The area-length method (r = 0.88) resulted in a slightly better correlation with left ventricular end-diastolic volume than did Simpson's rule (r = 0.85) or area-length (r = 0.84) formulas. For end-systolic volume, the three models yielded similar correlations: Simpson's rule (r = 0.94), area-length (r = 0.93) and diameter-length (r = 0.95). Each of the methods resulted in significant underestimation of diastolic and systolic volumes compared with values assessed with angiography (p less than 0.003). Ejection fraction was best predicted by using the Simpson's rule formula (r = 0.85) in comparison with area-length (r = 0.80) or diameter-length (r = 0.73) formulas. Measurements of left ventricular length by transesophageal echocardiography were smaller for systole (mean 5.7 +/- 1.6 cm) and diastole (mean 7.7 +/- 1.2 cm) than values by ventriculography (mean 9.2 +/- 1.4 and 8.1 +/- 1.6 cm, respectively; p less than 0.0001), suggesting that underestimation of the ventricular length is a major factor contributing to the smaller volumes obtained by transesophageal echocardiography. In conclusion, currently existing formulas can be applied to transesophageal images for predicting left ventricular volumes and ejection fraction. However, volumes obtained by these models are significantly smaller than those obtained with angiography, possibly because of foreshortening in the transesophageal four-chamber view.

Adult↗
PubMed1983

Coronary artery bypass grafting in patients with ejection fractions below forty percent. Early and late results in 466 patients.

The outcome of patients undergoing coronary artery bypass grafting with preoperative ejection fractions below 40% was evaluated to determine if a specific level of ventricular dysfunction resulted in unacceptably poor short-term or long-term survival rates. Left ventricular ejection fractions were segregated into groups of five percentage points each starting from 35% to 39% and progressing down to 10% to 14%. In evaluating the six ejection fraction groups between 10% and 39%, we found no significant differences among them with regard to previous myocardial infarctions, left ventricular end-diastolic pressure (LVEDP), age, preoperative New York Heart Association (NYHA) class, or number of vessels bypassed. Eighty-four percent were men and 16% women. From 1976 through 1982, 466 patients were distributed among these groups, all having ejection fractions below 40% (mean 30% +/- 3% SEM). There were significant differences (p = 0.001) in both the hospital and long-term survival (36 months) of patients with preoperative ejection fractions from 20% to 39% (425 patients) as compared to those with preoperative ejection fractions from 10% to 19% (41 patients). Hospital survival rate was 89% for patients with ejection fractions from 20% to 39% but only 63% for patients with ejection fractions below 20%. Similarly, at 3 years, patients with ejection fractions of 20% to 39% had an average survival rate of 60% as compared to an average survival rate of 15% for those with ejection fractions below 20%. Neither the preoperative LVEDP nor the intraoperative ischemic arrest time significantly predicted survival. In all survivors, NYHA class decreased from an average of 3.00 to 1.25 in surviving patients following bypass at a mean follow-up of 29 +/- 5 months. It is concluded that ejection fraction is an excellent predictor of short-term and long-term survival following coronary artery bypass grafting. Patients with ejection fractions of 10% to 19% have a significantly reduced short-term and long-term survival rate as compared to patients with ejection fractions of 20% or more.

Angina Pectoris↗
PubMed1986

Prediction of left ventricular ejection fraction using simple quantitative clinical information.

The left ventricular ejection fraction is useful in characterizing cardiac performance and evaluating prognosis in patients with known or suspected cardiac disease. The purpose of this study was to determine if simple, quantitative clinical information generated as part of a routine patient evaluation could be used to predict ejection fraction determined by radionuclide ventriculography. Multiple regression analysis was used to study a group of 64 patients selected to represent the full range of ejection fraction values. All patients had undergone cardiac catheterization and standard chest radiography in addition to resting and exercise radionuclide ventriculography. Using easily determined clinical variables, a regression formula was developed that predicted the radionuclide ventriculographic ejection fraction (r = 0.73). Plain film heart volume, heart rate, pulse pressure, and thoracic width were highly significant terms in the optimal regression equation. For validation, the formula was applied to a second, independent verification data set composed of 41 cases and revealed similar correlation (r = 0.78). A radionuclide ventriculographic ejection fraction below 40 was identified in the verification data set with a sensitivity of 87 percent and specificity of 83 percent. Use of this method, requiring only direct heart rate, blood pressure, and chest radiographic measurements and simple calculations, may assist physicians in patient management and facilitate the optimal use of more invasive and expensive studies.

Blood Pressure↗
PubMed1994

Thermodilution right ventricular ejection fraction measurements: room temperature versus cold temperature injectate.

OBJECTIVE: To compare thermodilution right ventricular ejection fraction measurements using 10 mL room temperature injectate vs. 10 mL cold temperature injectate. DESIGN: Prospective, clinical study. SETTING: Adult surgical intensive care unit (ICU) in a university hospital. PATIENTS: Sixty adult surgical ICU patients requiring hemodynamic monitoring by a pulmonary artery catheter. INTERVENTIONS: Patients were in a supine position with the bed flat during thermodilution measurements. Four 10 mL room temperature injections were alternated with four 10 mL cold temperature injections. MEASUREMENTS AND MAIN RESULTS: One hundred eleven paired thermodilution right ventricular ejection fraction measurements were made in patients during a "steady state." There were no restrictions regarding body temperature, cardiac index, heart rate or rhythm. Injectate temperature was measured by an in-line temperature probe. Injections were synchronized with end-expiration of mechanical ventilator breaths. The first injection was deleted from each temperature group. Reproducibility of individual right ventricular ejection fraction measurements was assessed by calculating the mean variation of triplicate measurements in each temperature group. Mean values of room temperature measurements were compared with cold temperature measurements by Student's t-test. Linear regression analysis, bias, and precision were also calculated. There was no significant difference (p = .752) between mean right ventricular ejection fraction measurements determined with room temperature (23.9 +/- 1 degrees C) vs. cold temperature (8.0 +/- 1.1 degrees C) injectate. There was a high degree of correlation between measurements (r2 = .876, p < .001). The bias of room temperature measurements compared with cold temperature was -0.39% and the precision was +/- 3.3%. The mean variation between individual measurements in all room temperature and cold temperature right ventricular ejection fraction measurements was 9.7% and 8.0%, respectively. There was no significant difference and there was a high degree of correlation in mean right ventricular ejection fraction measurements when data were grouped according to body temperature, heart rate, cardiac index, right ventricular ejection fraction, central venous pressure, pulmonary vascular resistance index, right ventricular end-diastolic volume index, or right ventricular stroke work index. CONCLUSIONS: The results suggest that room temperature injectate may be used for right ventricular ejection fraction measurements in critically ill adult surgical patients. Utilizing room temperature injectate for right ventricular ejection fraction measurements may save time and costs in the critical care unit.

Adult↗
PubMed1981

Ejection fraction response to exercise in patients with chest pain and normal coronary arteriograms.

In this study we describe the ejection fraction response to upright exercise using first-pass radionuclide angiocardiography in a group of 60 patients with chest pain, normal coronary arteriograms and normal resting ventricular function. A wide range of resting function (heart rate and ejection fraction) and exercise function (heart rate, ejection fraction, peak work load and estimated peak oxygen uptake) were measured. The ejection fraction response to exercise demonstrated wide variation, ranging from a decrease of 23% to an increase of 24%. Six of 22 clinical and radionuclide angiocardiographic variables (resting ejection fraction, peak work load, age, sex, body surface area and the change in end-diastolic volume index with exercise) were significant univariate predictors of the ejection fraction response to exercise. Multivariable analysis identified resting ejection fraction, the change in end-diastolic volume index with exercise and either sex or peak work load as variables that provided significant independent predictive information. These observations indicate that the ejection fraction response to exercise is a complex response that is influenced by multiple physiologic variables. The wide variation in this population suggests that the ejection fraction response to exercise is not a reliable test for the diagnosis of coronary artery disease because of its low specificity.

Adult↗
PubMed2005

Low ejection fraction: effect on the rehabilitation progress and outcome of stroke patients.

OBJECTIVE: To determine the effect of low ejection fraction ( 35%). DESIGN: A retrospective chart review of the 332 stroke patients admitted to the inpatient rehabilitation unit of an acute tertiary general hospital during a 36-mo period. A total of 262 (79%) of these patients (126 men and 136 women) had an ejection fraction study performed and are the subjects of this analysis. They were classified into two groups: low ejection fraction (n = 36) and high ejection fraction (n = 226). The main outcome measures included discharge total FIM score, FIM gain, FIM efficiency, length of stay, and discharge disposition. RESULTS: Patients with low ejection fraction had lower discharge FIM scores (82.9 vs. 89.1, t = 2.09, P < 0.04), lower FIM gain (15.9 vs. 19.3, t = 1.99, P < 0.05), and lower FIM efficiency (1.2 vs. 1.7, t = 232, P < 0.03), and they were less likely to return home (69% vs. 85%, chi 2= 5.25, P < 0.04) as compared with patients with high ejection fraction. Lengths of stay were not significantly different between the two groups. CONCLUSION: Compared with patients in the high ejection fraction cohort, the low ejection fraction subjects had lower discharge FIM scores, FIM gains, and FIM efficiency. However, almost 70% progressed well enough to be discharged to home. Low ejection fraction in stroke patients may well serve as an indicator of a patient population with greater medical and social needs.

Activities of Daily Living↗
PubMed1990

Heart failure with normal ejection fraction. The V-HeFT Study. Veterans Administration Cooperative Study Group.

In patients with clinical heart failure entered into the Veterans Administration Cooperative Study (V-HeFT) trial, 83 of 623 who had a baseline radionuclide measurement of left ventricular ejection fraction exhibited an ejection fraction of at least 0.45. When compared with the patients with an ejection fraction of less than 0.45, these subjects with apparent predominant diastolic dysfunction had a lower incidence of coronary artery disease (26.5% vs. 47.2%, p less than 0.001) and a higher incidence of preexisting hypertension (53.0% vs. 39.4%, p less than 0.02). In the normal ejection fraction group, systolic blood pressure was higher (129.7 vs. 117.7 mm Hg, p = 0.0001), heart rate slower (75.0 vs. 83.2 beats/min, p = 0.0001), cardiothoracic ratio smaller (0.512 vs. 0.536, p = 0.002), echocardiographic left ventricular dimension smaller in diastole (61.7 vs. 69.2 mm, p = 0.0001) and in systole (47.4 vs. 58.1 mm, p = 0.0001), and posterior wall thickness greater (9.0 vs. 7.9 mm, p = 0.004). Exercise tolerance was only slightly better in the normal ejection fraction group (peak oxygen consumption, 15.5 vs. 14.6 ml/kg/min, p = 0.04). Prognosis in the normal ejection fraction patients (annual mortality rate, 8.0%) was significantly better than in the low ejection fraction group (annual mortality rate, 19.0%) (p = 0.0001). Ventricular tachycardia on Holter monitor was a poor prognostic sign in these patients, and severe reduction in exercise tolerance also tended to predict poor outcome.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise Test↗
PubMed1994

Acute effects of external and internal pacing on ejection fraction in patients with severe cardiac failure.

The present study aims at evaluating the acute hemodynamic effects of external and internal (3 and 15 mA) pacing on 30 patients with severe cardiac failure. The global and regional ejection fraction were calculated by repeated radionuclide ventriculography at rest (control) and during increasing pacing rates. Blood pressure was measured at the end of each scintigraphy data acquisition period. The pacing rate was increased by 10 beats/min in every step and varied between +10 to +60 beats/min above the resting heart rate. The ejection fraction during pacing was lower than the resting ejection fraction in every pacing mode (resting ejection fraction = 23.30 +/- 7.67%, external pacing = 19.36 +/- 9.30%, p < 0.05, internal pacing 3 mA = 22.15 +/- 7.00%, p = N.S., internal pacing 15 mA = 19.92 +/- 6.95%, p < 0.05). The resting ejection fraction was higher than the ejection fraction in every pacing rate. In 4 out of 30 patients the ejection fraction was higher in every pacing mode and rate than the resting ejection fraction. The regional ejection fraction of the interventricular septum during internal pacing was lower (p < 0.001) than resting and/or external pacing. In conclusion, pacing in patients with severe cardiac failure reduces the control ejection fraction. This reduction increases as the pacing rate increases. The reduction is greater with internal pacing of 15 mA while the hemodynamic effect in external pacing did not differ significantly from internal pacing. Overall, the resting ejection fraction was higher than the paced ejection fraction, although in some patients pacing improved their resting ejection fraction.

Adult↗