Reconsidering the arm span-height relationship in patients referred for spirometry.

The interpretation of pulmonary function tests relies on reference values corrected for age, sex and height. Height may be difficult to measure in patients with deformities of the thoracic cage or those unable to stand up properly. Current practice is to substitute arm span to height, once corrected either by a fixed factor or by an age- and sex-dependent regression equation. However arm span may be difficult to measure in some patients. This study evaluated the relationship between arm span, measured height, height as mentioned on an identity document (ID), sex and age in a population of 2,452 Caucasian subjects with no chest or spine deformities. The present study demonstrates that age and sex have to be taken into account to best predict height from arm span or ID height values. The equations predicting height from ID height give the best diagnosis concordance compared to reference in males and females. Age correction does not improve concordance below 70 yrs. The estimation of height from ID height can be substituted to that from arm span when clinically relevant, providing ID height has been measured before the occurrence of stature problems.

Comparison of delayed enhancement patterns on multislice computed tomography immediately after coronary angiography and cardiac magnetic resonance imaging in acute myocardial infarction.

OBJECTIVE: Recent experimental and limited clinical studies have demonstrated the usefulness of delayed enhancement multislice computed tomography (MSCT) for assessing myocardial infarct size (IS) and transmurality. The aim of this study is to compare MSCT enhancement patterns immediately after coronary angiography (CAG) in an acute myocardial infarction (AMI) setting with cardiac magnetic resonance (CMR) enhancement during the second week follow-up. METHODS: 26 patients admitted for an AMI were evaluated by MSCT immediately after CAG without iodine re-injection. All but three were reperfused. The same patients had delayed enhancement CMR imaging at 10 (SD 4)-day follow-up. Myocardial enhancement was considered transmural (non-viable) when involving >75% of myocardial thickness, subendocardial (1 - < or =75%) or normal (viable for the two latter). Two or more >75% enhanced segments were required to define transmurality on patient-level or culprit artery-level analysis. A semi-quantitative scale score was defined for the 17 left ventricular segments. IS was computed from these scores. RESULTS: On segment analysis, sensitivity, specificity, accuracy, positive and negative predictive values of MSCT for transmurality assessment were 84%, 96%, 94%, 85% and 96%, respectively, compared to CMR. On patient analysis, these respective values were 90%, 80%, 88%, 95% and 67%. IS assessed by the two methods were highly correlated (r = 0.94, p<0.0001) and the regression line did not statistically differ from the identity line. CONCLUSION: MSCT enhancement immediately following CAG without iodine re-injection for an AMI is a reliable method for evaluating transmurality and IS. This very early evaluation could be an interesting alternative to CMR.

Evaluation of alterations on mitral annulus velocities, strain, and strain rates due to abrupt changes in preload elicited by parabolic flight.

We tested the hypothesis that in normal subjects, cardiac tissue velocities, strain, and strain rates (SR), measured by Doppler tissue echocardiography (DTE), are preload dependent. To accomplish it, immediately preceding image acquisition, reversible, repeatable, acute nonpharmacological changes in preload were induced by parabolic flight. DTE has been proposed as a new approach to assess left ventricular regional myocardial function by computing tissue velocities, strain, and SR. However, preload dependence of these parameters in normal subjects still remains controversial. DTE images (Philips) were obtained in 10 normal subjects in standing upright position at normogravity (1 Gz), hypergravity (1.8 Gz), and microgravity (0 Gz) with and without -50 mmHg lower body negative pressure (LBNP). Myocardial velocity curves in the basal interventricular septum were reconstituted offline from DTE images, from which peak systolic (S'), early (E') and late (A') diastolic velocities, SR, and peak systolic strain (PSepsilon) were measured and averaged over four beats. At 1.8 Gz (reduced venous return), S', E', and A' decreased by 21%, 21%, and 26%, respectively, compared with 1-Gz values, while at 0 Gz (augmented venous return), E', A', and PSepsilon increased by 57%, 53%, and 49%, respectively. LBNP reduced E' and PSepsilon. In conclusion, our results were in agreement with those obtained in animal models, in which preload was changed in a controlled, acute, and reversible manner, and image acquisition was performed immediately following preload modifications. The hypothesis of preload dependence was confirmed for S', E', A', and PSepsilon, while SR appeared to be preload independent, probably reflecting intrinsic myocardial properties.

[Dynamics of ECG voltage in changing gravity].

Comparative analysis of the QRS voltage response to gravity variations was made using the data about 26 normal human subjects collected in parabolic flights (CNERS-AIRBUS A300 Zero-G, n=23; IL-76MD, n=3) and during the tilt test (head-up tilt at 70 degrees for a min and head-down tilt at-15 degrees for 5 min, n=14). Both the parabolic flights and provocative tilt tests affected R-amplitude in the Z lead. During the hypergravity episodes it was observed in 95% of cases with the mean gain of 16% and maximal--56%. On transition to the horizontal position, the Rz-amplitude showed a rise in each subject (16% on the average). In microgravity, the Rz-amplitude reduced in 95% of the observations. The voltage decline averaged 18% and reached 49% at the maximum. The head-down tilt was conducive to Rz reduction in 78% of observations averaging 2%. Analysis of the ECG records under changing gravity when blood redistribution developed within few seconds not enough for serious metabolic shifts still revealed QRS deviations associated exclusively with the physical factors, i.e., alteration in tissue conduction and distance to electrodes. Our findings can stand in good stead in evaluation of the dynamics of predictive ECG parameters during long-term experiments leading to changes as in tissue conduction, so metabolism.

Objective evaluation of changes in left ventricular and atrial volumes during parabolic flight using real-time three-dimensional echocardiography.

We tested the feasibility of real-time three-dimensional (3D) echocardiographic (RT3DE) imaging to measure left heart volumes at different gravity during parabolic flight and studied the effects of lower body negative pressure (LBNP) as a countermeasure. Weightlessness-related changes in cardiac function have been previously studied during spaceflights using both 2D and 3D echocardiography. Several technical factors, such as inability to provide real-time analysis and the need for laborious endocardial definition, have limited its usefulness. RT3DE imaging overcomes these limitations by acquiring real-time pyramidal data sets encompassing the entire ventricle. RT3DE data sets were obtained (Philips 7500, X3) during breath hold in 16 unmedicated normal subjects in upright standing position at different gravity phases during parabolic flight (normogravity, 1 Gz; hypergravity, 1.8 Gz; microgravity, 0 Gz), with LBNP applied (-50 mmHg) at 0 Gz in selected parabolas. RT3DE imaging during parabolic flight was feasible in 14 of 16 subjects. Data were analyzed (Tomtec) to quantify left ventricular (LV) and atrial (LA) volumes at end diastole and end systole, which significantly decreased at 1.8 Gz and increased at 0 Gz. While ejection fraction did not change with gravity, stroke volume was reduced by 16% at 1.8 Gz and increased by 20% at 0 Gz, but it was not significantly different from 1 Gz values with LBNP. RT3DE during parabolic flight is feasible and provides the basis for accurate quantification of LV and LA volume changes with gravity. As LBNP counteracted the increase of LV and LA volumes caused by changes in venous return, it may be effectively used for preventing cardiac dilatation during 0 Gz.

Quantification of left ventricular modification in weightlessness conditions from the spatio-temporal analysis of 2D echocardiographic images.

Two-dimensional echocardiography (2DE) performed during flights with a parabolic trajectory to simulate weightlessness provides a unique means to study left ventricular (LV) modifications to prevent post-flight orthostatic intolerance in astronauts. However, conventional analysis of 2DE is based on manual tracings and depends on experience. Accordingly, the aim was objectively to quantify, from 2DE images, the LV modifications related to different gravity levels, by applying a semi-automated level-set border detection technique. The algorithm validation was performed by the comparison of manual tracing results, obtained by two independent observers with 20 images, with the semi-automated measurements. To quantify LV modifications, three consecutive cardiac cycles were analysed for each gravity phase (1 Gz, 1.8 Gz, 0 Gz). The level-set procedure was applied frame-by-frame to detect the LV endocardial contours and obtain LV area against time curves, from which end-diastolic (EDA) and end-systolic (ESA) areas were computed and averaged to compensate for respiratory variations. Linear regression (y = 0.91x + 1.47, r = 0.99, SEE:0.80cm2) and Bland-Altman analysis (bias = -0.58 cm2, 95% limits of agreement= +/- 2.14cm2) showed excellent correlation between the semi-automatic and manually traced values. Inter-observer variability was 5.4%, and the inter-technique variability was 4.1%. Modifications in LV dimensions during the parabola were found: compared with 1 Gz values, EDA and ESA were significantly reduced at 1.8 Gz by 8.8 +/- 5.5% and 12.1 +/- 10.1%, respectively, whereas, during 0 Gz, EDA and ESA increased by 13.3 +/- 7.3% and 11.6 +/- 5.1%, respectively, owing to abrupt changes in venous return. The proposed method resulted in fast and reliable estimations of LV dimensions, whose changes caused by different gravity conditions were objectively quantified.

ECG voltage modifications as response to gravity changes.

The aim of the study was to analyze ECG (QRS) voltage responses to body fluid shift due to gravity chances. Acute changes in gravity were created by two ways: 1) changes in gravity value during parabolic flights (within 27 subjects 45 ECG have been analyzed); 2) changes in gravity direction due to rotation of the body during postural tests (within 11 subjects 14 ECG have been analyzed). Results and conclusions. Gravity change leads to body fluid shift and changes of intrathoracic organs and tissues electroconduction. It influences on ECG voltage. During parabolic flights in up-right position: R amplitude in Z axis increases in hypergravity (+0.19 mV) and decreases in microgravity (-0.24 mV). During postural tests, R amplitude in Z axis increases in orthostatic position (+0.09 mV) and decreases in antiorthostatic position (-0.025 mV). Changes in QRS voltage during parabolic flights are more important than during postural tests. This could be due to more effective blood redistribution during parabolic flights.

Changes in Doppler mitral inflow patterns during parabolic flight.

Aim of the study was to evaluate by transthoracic Doppler the alterations in mitral inflow velocity pattern caused by acute changes in loading conditions occurring during parabolic flights. Each parabola included normogravity (1 Gz, 1 min), mild hypergravity (1.8 Gz, 20 sec), microgravity (0 Gz, 24 sec) and mild hypergravity (1.8 Gz, 20 sec) phases. Pulsed-Doppler images were digitally acquired in 11 unmedicated subjects (46 +/- 5 years), in standing upright position and supine resting. Doppler profiles were semi-automatically traced and inflow parameters extracted and averaged onto three consecutive beats. Only in standing position, significant alterations during microgravity (p<0.05) were noted in several parameters.

Feasibility of real-time 3D echocardiography in weightlessness during parabolic flight.

Aim of the study was to test the feasibility of transthoracic real-time 3D (Philips) echocardiography (RT3D) during parabolic flight, to allow direct measurement of heart chambers volumes modifications during the parabola. One RT3D dataset corresponding to one cardiac cycle was acquired at each gravity phase (1 Gz, 1.8 Gz, 0 Gz, 1.8 Gz) during breath-hold in 8 unmedicated normal subjects (41 +/- 8 years old) in standing upright position. Preliminary results, obtained by semi-automatically tracing left ventricular (LV) and left atrial (LA) endocardial contours in multiple views (Tomtec), showed a significant (p<0.05) reduction, compared to 1 Gz, of LV and LA volumes with 1.8 Gz, and a significant increase with 0 Gz. Further analysis will focus on the right heart.

Coronary events after arterial switch operation for transposition of the great arteries.

BACKGROUND: Transfer of the coronary arteries is a crucial step during the arterial switch operation (ASO) for transposition of the great arteries. This retrospective study aims to assess the incidence and risk factors of coronary events after ASO and sensitivity of noninvasive tests in the diagnosis of the coronary obstruction. METHODS AND RESULTS: Between 1982 and 2001, 1304 newborn and infants had an ASO and the 1 198 hospital survivors had a 59-month mean follow-up. Coronary events occurred in 94 patients (7.2%; 95% CI, 6 to 9). Survival without coronary events were 92.7, 91, and 88.2% at 1, 10, and 15 years, respectively. The incidence was bimodal: high early and slow later. Multivariate analysis showed correlation with type B or C coronary pattern and major operative events (P<0.0001 and P=0.0024). In a subset of 324 patients who underwent a coronary artery angiography, lesions were observed in 22 patients (6.8%; 95% CI, 5 to 10). Multivariate analysis showed correlation with only type B or C coronary pattern (OR=20.8, P=0.0002). All of these patients had electrocardiogram and echocardiogram, 174 patients also had a treadmill test, and 115 patients had a myocardial scintigraphy. The association of these tests had the highest diagnosis sensitivity, 75%. CONCLUSIONS: After ASO, coronary events are not rare, occurring most often early and are an important cause of death. Coronary repair can be needed lately. Noninvasive tests are not sensitive enough to detect significant delayed coronary artery stenosis and coronary artery angiography should be performed.

[Prevalence and diagnosis of coronary lesions after arterial switch]. / Prévalence et dépistage des lésions coronaires après switch artériel.

In anatomical repair procedure of transposition of the great arteries (arterial switch), translocation of the coronary arteries is crucial and coronary complications remain the principal cause of death. The aim of this retrospective study was to assess the prevalence of coronary lesions and to evaluate the diagnostic methods to prevent their consequences. From 1982 to 2001, 1,304 patients were operated for transposition of the great arteries by the switch procedure at the Marie Lannelongue Surgical Centre. The average follow-up of the survivors was 59 months (3 days to 17 years) during which 324 patients underwent coronary angiography. All had an ECG and an echocardiogram (N = 324); 174 underwent exercise stress testing and 115 had myocardial scintigraphy. Of the 324 patients who underwent coronary angiography, 22 had coronary lesions (6.8%; 95% CI 5-10). In multivariate analysis a type II coronary network by the Marie Lannelongue Classification was related to the risk of coronary lesions (OR = 0.28; p < 0.0002). Each non-invasive method studied separately had a low sensitivity (< 50%) for the detection of these lesions. The association of ECG, echocardiography and myocardial scintigraphy had the best sensitivity at 75%. Therefore, after the arterial switch procedure non-invasive investigations are not sensitive enough to diagnose coronary lesions and systematic coronary angiography and aortography should be performed in all patients.

Effect of gravity and posture on lung mechanics.

The volume-pressure relationship of the lung was studied in six subjects on changing the gravity vector during parabolic flights and body posture. Lung recoil pressure decreased by approximately 2.7 cmH(2)O going from 1 to 0 vertical acceleration (G(z)), whereas it increased by approximately 3.5 cmH(2)O in 30 degrees tilted head-up and supine postures. No substantial change was found going from 1 to 1.8 G(z). Matching the changes in volume-pressure relationships of the lung and chest wall (previous data), results in a decrease in functional respiratory capacity of approximately 580 ml at 0 G(z) relative to 1 G(z) and of approximately 1,200 ml going to supine posture. Microgravity causes a decrease in lung and chest wall recoil pressures as it removes most of the distortion of lung parenchyma and thorax induced by changing gravity field and/or posture. Hypergravity does not greatly affect respiratory mechanics, suggesting that mechanical distortion is close to maximum already at 1 G(z). The end-expiratory volume during quiet breathing corresponds to the mechanical functional residual capacity in each condition.

Changes of decartograms under gravitational acceleration and microgravity.

The Decarto technique was used to study the orthogonal ECGs recorded in 23 subjects during parabolic flights (44 records). A parameter of the instantaneous decartograms, namely the activation area (AA), which is the total area of the depolarization front projection on the image sphere, was analyzed. We compared the values of AA during the periods of horizontal flight, upward parts of all parabolas, and the initial 10 s of microgravity of all parabolas. According to the characteristics of the vectorcardiograms and AA, all subjects were subdivided into 3 groups: with increased electric activity of the right ventricle (I), the left ventricle (II) and both ventricles (III). Changes of AA with change of gravitational levels in these groups showed some differences. In groups I and II, the AA of the initial part of the QRS complex increased during microgravity and decreased during hypergravity. In group III it decreased during microgravity and changed variously during hypergravity. The AA of the middle part of the QRS complex decreased during microgravity and increased during hypergravity, and these changes were more pronounced in group III. The changes of AA in groups I and II may be explained by the Brody effect. In group III, AA seems to be influenced by some additional factors, possibly by changes in the intramyocardial or intraventricular blood volume. The AA of the last part of the QRS complex increased during microgravity and decreased during hypergravity in all groups. This may be explained by an effect of mutual neutralization of depolarization fronts related to the changes of the QRS duration.(Fig. 3, Ref. 4)

Effect of gravity on chest wall mechanics.

Chest wall mechanics was studied in four subjects on changing gravity in the craniocaudal direction (G(z)) during parabolic flights. The thorax appears very compliant at 0 G(z): its recoil changes only from -2 to 2 cmH(2)O in the volume range of 30-70% vital capacity (VC). Increasing G(z) from 0 to 1 and 1.8 G(z) progressively shifted the volume-pressure curve of the chest wall to the left and also caused a fivefold exponential decrease in compliance. For lung volume <30% VC, gravity has an inspiratory effect, but this effect is much larger going from 0 to 1 G(z) than from 1 to 1.8 G(z). For a volume from 30 to 70% VC, the effect is inspiratory going from 0 to 1 G(z) but expiratory from 1 to 1.8 G(z). For a volume greater than approximately 70% VC, gravity always has an expiratory effect. The data suggest that the chest wall does not behave as a linear system when exposed to changing gravity, as the effect depends on both chest wall volume and magnitude of G(z).

Changes in left ventricular size during parabolic flights by two-dimensional echocardiography and level set method.

This study aims to evaluate changes on cardiac chambers size, induced by gravitational stresses. During parabolic flight, seven subjects underwent 2-D transthoracic echocardiography at three different gravity phases (1 Gz, 1.8 Gz, and 0 Gz). LV endocardial borders were detected applying a semi-automatic segmentation procedure based on level set methods. LV cavity area was computed frame-by-frame for a whole cardiac cycle during each gravity phase. Expected modifications in LV area with different gravity were found: at 1.8 Gz, end-diastolic (ED) and end-systolic (ES) areas were significantly (p<0.05) reduced of 10.7 +/- 5.4% and 21.6 +/- 11.1% respectively, compared to 1 Gz values, while they were increased of 11.2 +/- 5.4% and 11.1 +/- 6% during 0 Gz. Fractional area change was augmented of 20.9 +/- 29.1% at 1.8 Gz, while it remained unchanged at 0 Gz, compared with 1 Gz values. Furthermore, LV filling due to atrial contraction was increased at 0 Gz of 39 +/- 35.6%.

Time-variant spectral analysis of heart rate variability during parabolic flight with and without LBNP.

Modifications of autonomic activity during parabolic flight were studied by a time-variant model able to estimate low (LF, 0.04-0.14 Hz) and high (HF, 0.14-0.35 Hz) frequency spectral components on a beat-to-beat basis. Ten subjects were studied with and without lower body negative pressure (LBNP). ECG and Gz load were digitized (500 Hz) and RR interval variability series extracted. Beat-to-beat mean RR, variance, LF and HF power were obtained. One-way ANOVA (p<0.01) was used to compare values obtained during starting 1Gz (I), first 1.8Gz (II), 0Gz (III), second 1.8Gz (IV), ending 1Gz (V). Without LBNP, total and LF power increased during 0Gz to 1.69 +/- 1.41 and 2.87 +/- 4.66 respectively (mean +/- SD, normalized by phase I value). With LBNP, their change during 0Gz (1.38 +/- 1.37 and 1.54 +/- l.04 respectively) reached significance only with phase II and phase V. Phase I HF power was higher than in the other phases, both without and with LBNP.

Late outcome after arterial switch operation for transposition of the great arteries.

BACKGROUND: Early and midterm results of the arterial switch operation (ASO) in transposition of the great arteries (TGA) are good, but late outcome data in large populations are still few. METHODS AND RESULTS: Twelve hundred patients had an ASO for TGA between 1982 and 1999, with prospective follow-up of 1095 survivors. Outcome measures included late death, reoperation, aortic insufficiency (AI), pulmonary stenosis (PS), and coronary anomaly. Median follow-up was 4.9 years (range 0.5 to 17 years). Late death occurred in 32 patients; survival was 88% at both 10 and 15 years. The hazard function for death declined rapidly, with no deaths after 5 years. Late mortality was correlated with reintervention and major events in the intensive care unit. Reoperation was performed in 103 patients, more often in complex TGA; the cause was mainly PS. Freedom from reintervention was 82% at 10 and 15 years, with a hazard function that declined rapidly but slowly increased after 3 years. At the last follow-up, PS was present in 3.9% of patients, and grade II or more AI was present in 3.2%, with a cumulative incidence of 9% at 15 years. Among the 278 patients who had a coronary arteriography, 8% had coronary lesions. Normal left ventricle and sinus rhythm were seen in 96.4% and 98.1%, respectively. CONCLUSIONS: Fifteen years after ASO, late mortality was low, with no deaths after 5 years; reoperation, mainly owing to PS, occurred throughout the follow-up. AI and coronary obstruction are rare but warrant further follow-up. Good left ventricular function and sinus rhythm are maintained.

Parasympathetic activity during parabolic flight, effect of LBNP during microgravity.

BACKGROUND/HYPOTHESIS: During parabolic flight, in the standing position, changes are partly due to an acute shift in fluid between the lower extremities, the head and the thorax (Vaïda P, et al. J Appl Physiol 1997; 82:1091-7; and Bailliart O, et al. J Appl Physiol 1998; 85:2100-5). We hypothesized that modifications of parasympathetic activity associated with changes in hydrostatic pressure gradients induced by changes in gravity could be detected by analysis of short time periods. METHODS: We assessed heart rate variability (HRV) in 11 healthy volunteers by indices of temporal analysis (NN, SDNN, RMSSD) and normalized indices such as coefficients of variation CV-SDNN and CV-RMSSD and ratio SDNN/RMSSD. A lower body negative pressure (LBNP) at -50 mm Hg was randomly applied during the microgravity phase (0 Gz) to counteract the lack of hydrostatic pressure in the lower part of the body. RESULTS: NN, CV-SDNN and CV-RMSSD decreased during hypergravity phases and increased during microgravity and during early normogravity (1 Gz) period at the end of parabolas. With LBNP changes are less pronounced at 0 Gz and in the 1 Gz post parabolic period. CONCLUSION: We concluded that parasympathetic nervous activity is recordable by temporal analysis of HRV during short periods of time. LBNP applied during 0 Gz phase reduced the parasympathetic activation at 0 Gz and post parabolic 1 Gz.

Pulmonary blood flow distribution in stage 1 chronic obstructive pulmonary disease.

We investigated the hypothesis that lung blood flow distribution is modified in stage 1 chronic obstructive pulmonary disease (COPD). We compared patients with stage 1 COPD (n = 11) with restrictive patients with comparable blood gases (n = 7), to patients with low cardiac index with normal lungs (n = 11) and to control subjects (n = 11). Distribution of transit time (DTT) was computed by deconvolution from first pass radioactivity curves (albumin (99m)Tc) reconstructed from right and left ventricular regions of interest. Distribution descriptors, mean transit time (p < 0.05), standard deviation (p < 0.001), relative dispersion (p < 0.001), and kurtosis (p < 0.001) differed between groups (ANOVA). Cardiac index was the same in COPD and low CI groups but lower compared with normal subjects (p < 0.05). After normalization for cardiac output, the DTT of patients with COPD remained different from low CI and restrictive patients (p < 0.001). Therefore changes in DTT in patients with COPD compared with patients without COPD could not be explained on the basis of difference in cardiac output. Because P(O(2)), PC(O(2)), and pH were similar in COPD and restrictive groups, difference in distribution could not be explained either on the basis of blood gas data. We conclude that changes in DTT occurs in stage 1 COPD and cannot be explained by hypoxemia, hypercapnia, or acidosis alone but must relate to other structural or regulatory responses.