Benoit Diebold

Pulsatile diameter and elastic modulus of the aortic arch in essential hypertension: A noninvasive study

A noninvasive evaluation of the aortic arch diameter was performed in 16 subjects with sustained essential hypertension and in 15 normal subjects of similar age, gender and body surface area. In all subjects, measurements were obtained of brachial mean arterial pressure and pulse pressure, cardiac mass (judged on echocardiography) and carotid-femoral pulse wave velocity together with ultrasound determinations of aortic arch diastolic and systolic diameter (suprasternal window). For each subject, pulsatile change in aortic diameter, strain and aortic arch elastic modulus were calculated. Compared with normal subjects, the hypertensive subjects showed an increase in aortic arch diameter (diastolic diameter 29.6 +/- 1.0 versus 25.4 +/- 1.0 mm, p less than 0.01), in elastic modulus (1.071 +/- 0.131 versus 0.526 +/- 0.045 10(5) N.m-2, p less than 0.001) and pulse wave velocity (11.8 +/- 0.5 versus 8.9 +/- 0.3 m/s, p less than 0.001). In the study group, a positive correlation was observed between diastolic aortic arch diameter and mean arterial pressure (r = 0.54, p less than 0.01) and between elastic modulus and cardiac mass (r = 0.60, p less than 0.01). Elastic modulus and age were positively correlated (r = 0.73, p less than 0.01) in hypertensive but not in normal subjects (r = 0.08, NS). This study is the first to demonstrate noninvasively that both the aortic arch diameter and the elastic modulus are increased in patients with sustained uncomplicated essential hypertension. These findings suggest that the increase in elastic modulus could influence the development of cardiac hypertrophy, and that both age and blood pressure act independently as factors that alter the arterial wall of subjects with sustained essential hypertension.

Mapping of a First Locus for Autosomal Dominant Myxomatous Mitral-Valve Prolapse to Chromosome 16p11.2-p12.1

Myxomatous mitral-valve prolapse (MMVP), also called Barlow disease, is a common cardiac abnormality and affects up to 5% of the population. It is characterized by an excess of tissue that leads to billowing of the mitral leaflets, sometimes complicated by prolapse. Typical histological findings include myxomatous degeneration and degradation of collagen and elastin. Previous reports have proposed an autosomal dominant inheritance of the trait, with age- and sex-dependent expression. By systematic echocardiographic screening of the first-degree relatives of 17 patients who underwent mitral-valve repair, we have identified four pedigrees showing such an inheritance. Genomewide linkage analysis of the most informative pedigree (24 individuals, three generations) showed a significant linkage for markers mapping to chromosome 16p, with a two-point maximum LOD score for D16S3068 (Zmax=3.30 at straight theta=0). Linkage to D16S3068 was confirmed in a second family (Zmax=2.02 at straight theta=0) but was excluded for the two remaining families, thus demonstrating the genetic heterogeneity of the disease. Multipoint linkage analysis performed, with nine additional markers, on the two families with linkage gave maximum multipoint LOD scores of 5.45 and 5.68 for D16S3133, according to a conservative and a stringent model, respectively. Haplotype analysis defined a 5-cM minimal MMVP-1 locus between D16S3068 (16p11.2) and D16S420 (16p12. 1) and a 34-cM maximal interval between D16S404 and D16S3068 when recombination events were taken into account only in affected individuals. The identification of this locus represents a first step toward a new molecular classification of mitral-valve prolapse.

Basal Asynchrony and Resynchronization with Biventricular Pacing Predict Long-Term Improvement of LV Function in Heart Failure Patients

Biventricular pacing (BiV) is emerging for patients with dilated cardiomyopathy (DCM) and asynchrony. We measured basal asynchrony and early resynchronization by radionuclide angioscintigraphy (RNA) in order to predict long‐term evolution of ventricular function after BiV. Thirty‐four patients (NYHA Class III–IV, 65.4 ± 11 years ) with large QRS (179 ± 18 ms) were implanted with BiV and studied by RNA before (D0), at day 8 (D8), and during follow‐up (20 ± 7 months) . We calculated left and right ejection fractions, the interventricular dyssynchrony (TRVLV), and the apicobasal dyssynchrony (Tab). LVEF improved from 20.2 ± 8.1% (D0) to 27.1%± 12.6% (follow‐up, P < 0.003 vs D0) and RVEF from 28.6%± 13% (D0) to 34.3 ± 11.5% (follow‐up, P < 0.03 vs D0). Inter‐ (ΔTRVLV) and intraventricular resynchronization was immediate and remained stable: TRVLV decreased from 68.3 ± 38 ms (D0) to 13.4 ± 48.5 ms (D8) and 1.8 ± 39.2 ms (follow‐up, P < 0.0001 vs D0); and Tab from 45.8 ± 64.1 ms to −18 ± 68 (D8) and −28.3 ± 53.6 ms (follow‐up, P < 0.0001 vs D0). Early inter‐ and intraventricular resynchronization (ΔTab) at D8 were related to late LVEF and RVEF improvement. Together, an LVEF > 15% and a significant interventricular dyssynchrony (TRVLV > 60 ms) at D0 have a sensitivity of 79% and a positive predictive value of 83% to predict an improvement of LVEF superior to 5% at follow‐up. In DCM patients, BiV resynchronizes ventricles early and in the long‐term, while RVEF and LVEF improve progressively. Patients with large electromechanical dyssynchrony benefit most from BiV. (PACE 2003; 26:1815–1823)

Geometric Features of Coronary Artery Lesions Favoring Acute Occlusion and Myocardial Infarction: A Quantitative Angiographic Study

OBJECTIVES We sought to identify the angiographic predictors of a future infarction, to study their interaction with time to infarction, patient risk factors and medications, and to evaluate their clinical utility for risk stratification. BACKGROUND Identification of coronary lesions at risk of acute occlusion remains challenging. Stenosis severity is poorly predictive but other stenosis descriptors might be better predictors. METHODS Eighty-four patients with an acute myocardial infarction and a coronary angiogram performed within the preceding 36 months (baseline angiogram), and after infarction were selected. All coronary stenoses (from 10% to 95% lumen diameter reduction) at baseline angiogram were analyzed by computer-assisted quantification. Each of the 84 lesions responsible for the infarction (culprit) was compared with the nonculprit stenoses (controls) in the same patient. RESULTS Culprit lesions were more symmetrical (symmetry index +15%; p < 0.001), had steeper outflow angles (maximal angle +4 degrees; p < 0.001), were more severe (percent stenosis +5%; p = 0.001) and longer (+ 1.5 mm, p = 0.01) than controls. The symmetry index and the outflow angles were the two independent predictors of infarction at three-year follow-up. Stenosis severity predicted only infarctions occurring within 1 year after angiography. In moderately severe stenoses (40% to 70% stenosis), stratification using the symmetry index and outflow angles accurately predicted lesions remaining free of occlusion and infarction at three-year follow-up. CONCLUSIONS Better characterization of stenosis geometry might help to understand the pathophysiologic mechanisms triggering coronary occlusion and to stratify patients for improved care.

Two-Dimensional Strain Rate and Doppler Tissue Myocardial Velocities: Analysis by Echocardiography of Hemodynamic and Functional Changes of the Failed Left Ventricle during Different Degrees of Extracorporeal Life Support

BACKGROUND To evaluate hemodynamic and functional changes of the failed left ventricle by Velocity Vector Imaging (VVI) and tissue Doppler, 22 patients with cardiogenic shock supported by extracorporeal life support (ECLS) were imaged during ECLS output variations inducing severe load manipulations. METHODS The following data were acquired: (1) mean arterial pressure, aortic Doppler velocity-time integral, left ventricular end-diastolic volume, and mitral Doppler E wave; (2) tissue Doppler systolic (Sa) and early diastolic (Ea) velocities; and (3) systolic peak velocity (Sv), strain, and strain rate using VVI. RESULTS Load variations were documented by a significant decrease in afterload (mean arterial pressure, -21%), an increase in preload (left ventricular end-diastolic volume, +12%; E, +46%; E/Ea ratio, +22%), and an increase in the velocity-time integral (+45%). VVI parameters increased (Sv, +36%; strain, +81%; and strain rate, +67%; P < .05), unlike tissue Doppler systolic velocities (+2%; P = NS). Whatever the ECLS flow, Sa was higher in patients who survived. CONCLUSIONS VVI parameters are not useful in characterizing the failed left ventricle with rapidly varying load conditions. Tissue Doppler systolic velocities appear to be load independent and thus could help in the management of ECLS patients.

The age of the patient should be taken into account when interpreting Doppler assessed pulmonary artery pressures

The impact of aging on the systolic artery pressure (SPAP) value is not well known. We selected 134 echocardiographic Doppler examinations considered as normal (presence of a sinus rhythm, absence of chronic obstructive pulmonary disease or pulmonary embolism, normal global or segmental wall motion, no right or left ventricular hypertrophy or dilatation, no significant valvular disease, no pericarditis), with a clearly measurable tricuspid insufficiency allowing us to measure the SPAP with the simplified Bernoulli equation. There was a highly significant (p = 0.0001) correlation (r = 0.47) between SPAP values and the age of the patient. SPAP increased progressively with age from 23 +/- 5 mm Hg between 20 to 29 years old to 32 +/- 6 mm Hg when 80 years old or more. The interpretation of the SPAP should take into account the age.

Automated left ventricular diastolic function evaluation from phase-contrast cardiovascular magnetic resonance and comparison with Doppler echocardiography

BackgroundEarly detection of diastolic dysfunction is crucial for patients with incipient heart failure. Although this evaluation could be performed from phase-contrast (PC) cardiovascular magnetic resonance (CMR) data, its usefulness in clinical routine is not yet established, mainly because the interpretation of such data remains mostly based on manual post-processing. Accordingly, our goal was to develop a robust process to automatically estimate velocity and flow rate-related diastolic parameters from PC-CMR data and to test the consistency of these parameters against echocardiography as well as their ability to characterize left ventricular (LV) diastolic dysfunction.ResultsWe studied 35 controls and 18 patients with severe aortic valve stenosis and preserved LV ejection fraction who had PC-CMR and Doppler echocardiography exams on the same day. PC-CMR mitral flow and myocardial velocity data were analyzed using custom software for semi-automated extraction of diastolic parameters. Inter-operator reproducibility of flow pattern segmentation and functional parameters was assessed on a sub-group of 30 subjects. The mean percentage of overlap between the transmitral flow segmentations performed by two independent operators was 99.7 ± 1.6%, resulting in a small variability (<1.96 ± 2.95%) in functional parameter measurement. For maximal myocardial longitudinal velocities, the inter-operator variability was 4.25 ± 5.89%. The MR diastolic parameters varied significantly in patients as opposed to controls (p < 0.0002). Both velocity and flow rate diastolic parameters were consistent with echocardiographic values (r > 0.71) and receiver operating characteristic (ROC) analysis revealed their ability to separate patients from controls, with sensitivity > 0.80, specificity > 0.80 and accuracy > 0.85. Slight superiority in terms of correlation with echocardiography (r = 0.81) and accuracy to detect LV abnormalities (sensitivity > 0.83, specificity > 0.91 and accuracy > 0.89) was found for the PC-CMR flow-rate related parameters.ConclusionsA fast and reproducible technique for flow and myocardial PC-CMR data analysis was successfully used on controls and patients to extract consistent velocity-related diastolic parameters, as well as flow rate-related parameters. This technique provides a valuable addition to established CMR tools in the evaluation and the management of patients with diastolic dysfunction.

In vitro flow quantification with contrast power Doppler imaging

To evaluate the effectiveness of contrast harmonic (power Doppler imaging) as an ultrasonic modality to quantify flow, an in vitro model of perfusion was studied using Optison, a second-generation ultrasound (US) contrast agent. The in vitro model was made of two dialysis cartridges placed parallel and allowed absolute and relative flow quantification on both tube (entry lines) and tissue (cartridges) simulations. Video intensity curves were generated using intermittent harmonic power Doppler imaging after bolus injection of contrast. Correlation between flow and different parameters extracted from time-intensity curves and previously defined as indicators of flow was established for both tissue and entry lines, for flow rates ranging from 0 to 400 mL/min. Single-compartment equations were also tested on the model. A good correlation for the tissue model was observed between absolute flow and onset time (O), time to maximal enhancement (TME), peak intensity (P), area under the curve (AUC), and maximal ascending slope (S) parameters, with a r = 0.94, 0.94, 0.91, 0.92 and 0.92, respectively. The correlation for O, TME, P and AUC parameters was r = 0.86, 0.90, 0.78 and 0.82, respectively for entry lines. The correlation for tissue model and entry line was slightly improved when comparing flow ratios with peak ratios (P1/P2) and slope ratios (S1/S2) (r = 0.95 and 0.94). Flow calculation using the gradient-relationship method also showed a good correlation (r = 0.88) with the experimental flow. The results obtained indicated that absolute and relative quantification of flow using PDI is feasible in tube and tissue models. Several clinical applications, namely in myocardial, hepatic and renal artery studies, could be derived from these results.

Assessment of left ventricular contraction by parametric analysis of main motion (PAMM): theory and application for echocardiography

The computerized study of the regional contraction of the left ventricle has undergone numerous developments, particularly in relation to echocardiography. A new method, parametric analysis of main motion (PAMM), is proposed in order to synthesize the information contained in a cine loop of images in parametric images. PAMM determines, for the intensity variation time curves (IVTC) observed in each pixel, two amplitude coefficients characterizing the continuous component and the alternating component; the variable component is generated from a mother curve by introducing a time shift coefficient and a scale coefficient. Two approaches, a PAMM data driven and a PAMM model driven (simpler and faster), are proposed. On the basis of the four coefficients, an amplitude image and an image of mean contraction time are synthesized and interpreted by a cardiologist. In all cases, both PAMM methods allow better IVTC adjustment than the other methods of parametric imaging used in echocardiography. A preliminary database comprising 70 segments is scored and compared with the visual analysis, taken from a consensus of two expert interpreters. The levels of absolute and relative concordance are 79% and 97%. PAMM model driven is a promising method for the rapid detection of abnormalities in left ventricle contraction.

Pulsed doppler echocardiographic study of mitral stenosis

SUMMARYThe value of pulsed Doppler echocardiography in the assessment of mitral stenosis was studied in a consecutive series of 175 patients before right- and left-heart catheterization. All Doppler recordings were interpreted independently by two observers. Twenty patients had repeat studies to demonstrate the reproducibility of the method. Adequate recordings were obtained in 156 patients. A normal flow pattern was observed in all 41 patients in sinus rhythm without a mitral valve gradient but in none of the 51 patients in sinus rhythm with a mitral gradient. In atrial fibrillation the normal pattern was identified in all three patients with no mitral gradient but in none of the 61 with a gradient. Three patterns of mitral valve flow could be distinguished that corresponded to mild, moderate and severe stenosis. The mitral valve gradient in the 36 patients with pattern I was 6.1 ± 1.7 mm Hg (SD) (range 3–10 mm Hg); in 54 patients with pattern II it was 12.0 ± 2.5 mm Hg (range 8–18 mm Hg) (p < 0.001 vs I); in 22 patients with pattern III it was 22.0 ± 2.6 mm Hg (range 18–27 mm Hg) (p < 0.001 vs II). Overlap was observed in only four patients, all of whom had a gradient between 8–10 mm Hg. Mitral valve area was 2.14 ± 0.58 cm2 in pattern I, 1.17 ± 0.33 cm2 in pattern II and 0.67 ± 0.26 cm2 in pattern III (p < 0.001 between all groups). The presence of associated mitral regurgitation in 39 patients and aortic valve disease in 32 patients did not affect the Doppler assessment of mitral stenosis. Thus, pulsed Doppler echocardiography can accurately detect the presence of mitral stenosis and assess its severity.