Biomedical subjects

Fadi Jamal

Publications and source records attributed to Fadi Jamal.

8 recordsLinked to original sources

PubMed2003

Longitudinal strain quantitates regional right ventricular contractile function.

The assessment of contractile function of the right ventricle (RV) is an important clinical issue, but this remains difficult because of its complex anatomy and structure. We thought to investigate whether new Doppler-derived myocardial deformation indexes may quantify regional contractile RV function during varying loading conditions. In nine pigs, ultrasonic crystals were inserted longitudinally in the RV inflow and outflow tracts to assess regional contractile function. The same RV segments and the interventricular septum were imaged using apical echocardiographic views. Regional function was assessed using two parameters: 1) systolic strain (SS), representing the relative magnitude of segmental systolic shortening; and 2) its temporal derivative, peak systolic strain rate (SR), i.e., the maximal velocity of segmental shortening. Data were acquired at baseline and during partial pulmonary artery constriction (PAC) and inferior vena cava occlusion (IVCO). SS decreased significantly after PAC and IVCO in both the inflow and outflow tracts but only during IVCO in the septum. SR was less sensitive to loading variations in all segments. A significant correlation was found between SS values derived from sonomicrometry and myocardial Doppler in RV segments (r = 0.84, P < 0.001). Thus regional strain and SR provide complementary information on the heterogeneous RV contractile function and can be accurately and noninvasively quantified using Doppler myocardial imaging.

Animals↗

PubMed2003

Identification of acutely ischemic myocardium using ultrasonic strain measurements. A clinical study in patients undergoing coronary angioplasty.

OBJECTIVES: The goal of this study was to investigate whether the changes in myocardial deformation measured with ultrasonic strain could accurately identify acutely ischemic myocardium during coronary angioplasty. BACKGROUND: Early identification of acute myocardial ischemia has important clinical implications. The accuracy of ultrasonic strain for the detection of acute myocardial ischemia has been validated in animal experiments but has not been investigated in the clinical setting. METHODS: In 73 patients (64 +/- 12 years), either radial or longitudinal strain values were monitored in the "at-risk" segments before, during, and early after right, circumflex, and left anterior descending coronary angioplasty. Based on the visual wall motion assessed before the angioplasty, segments were divided into normokinetic (group I) and hypo/akinetic (group II). Strain data in the "at-risk " segments were compared with values derived from the adjacent nonischemic segments and normal values in 20 controls. RESULTS: Coronary occlusion induced a marked reduction in the systolic strain both in the radial (from 49 +/- 6.9% to 23 +/- 4.6% in group I and from 21.9 +/- 11% to 11.3 +/- 8.4% in group II, p < 0.001) and longitudinal directions. Concomitantly, postsystolic strain increased (from 3.8 +/- 3.1% to 14.6 +/- 9.5% in group I, and from 4.4 +/- 3.7% to 11.3 +/- 7.8% in group II in radial direction, p < 0.001). Upon reperfusion, all deformation parameters returned to near preocclusion values. In comparison with control, baseline, and reperfusion data, the systolic and postsystolic strain parameters measured during total coronary occlusion identified acutely ischemic myocardium with a sensitivity of 86% to 95% and a specificity of 83% to 89%. CONCLUSIONS: In this model of acute ischemia, ultrasonic strain indexes differentiate acutely ischemic segments from both normal and dysfunctional myocardium. This should be a promising new approach to the bedside monitoring of acute ischemic changes in regional myocardial function.

Acute Disease↗

PubMed2002

Acute changes in systolic and diastolic events during clinical coronary angioplasty: a comparison of regional velocity, strain rate, and strain measurement.

Ultrasound-derived natural strain rate and strain are new Doppler myocardial imaging (DMI) parameters, which can measure local deformation independently of overall heart motion and thus could better characterize local contractility than DMI velocities alone. This study was undertaken to evaluate the relative benefits of regional velocity, strain rate, and strain measurements in detecting the range of acute changes in regional myocardial function in the "at-risk" zone during coronary angioplasty. Sixty-one patients (aged 63 +/- 12, 18 women) with stable angina pectoris were studied before, at the end of, and during recovery from a 60-second percutaneous transluminal coronary angioplasty (PTCA) balloon occlusion. High frame rate (147 fps) color DMI regional velocity data were derived from basal posterior (parasternal view) and mid, apical septal (apical view) "at-risk" segments as well as from the corresponding segments in healthy subjects and analyzed offline for velocity (VEL), strain rate (SR), and strain (epsilon) measurements. Coronary occlusion resulted in the reduction in VEL(SYS), SR(SYS), and epsilon(SYS) values for both radial (RCA/CX occlusion) and longitudinal data (LAD occlusion) in all segments analyzed. Velocity parameters alone failed to distinguish between baseline and occlusive measurements in the "at-risk" segments with visually abnormal baseline function. SR(SYS) and epsilon(SYS) had a higher diagnostic accuracy (sensitivity 75%, 80% and specificity 80%, 82%, respectively) than VEL(SYS) velocity alone (sensitivity 68%, specificity 65%,) for identifying acute ischemia in either baseline normal and abnormal segments. DMI-derived indexes can identify and quantify the spectrum of acute systolic and diastolic ischemic changes induced during clinical PTCA. The quantitation of regional deformation rather than motion would appear to be more appropriate in detecting and quantifying acute ischemic changes in myocardial function, especially in segments with pre-existing abnormal function.

Adult↗

PubMed2002

Quantification of regional left and right ventricular radial and longitudinal function in healthy children using ultrasound-based strain rate and strain imaging.

BACKGROUND: Noninvasive assessment of left (LV) and right (RV) ventricular function in children could benefit from a technique that would characterize local myocardial deformation. Color Doppler myocardial imaging (CDMI) allows the calculation of either local longitudinal or radial Strain Rate (SR) and Strain (epsilon). To determine the clinical feasibility and reproducibility of longitudinal and radial SR and epsilon, the following study was carried out. METHODS: CDMI data were obtained from 33 healthy children (4-16 years). To quantify regional longitudinal and radial function SR and epsilon data were obtained from apical and parasternal views respectively. From the extracted SR curves, peak values for systole, early diastole, and late diastole were calculated. From the extracted epsilon curves the systolic, early and late diastolic epsilon values were calculated. RESULTS: LV longitudinal deformation were homogeneous for LV basal, mid and apical segments (peak systolic SR: -1.9 +/- 0.7 s(-1), systolic epsilon -25% +/- 7%). Longitudinal SR and epsilon values were significantly higher and heterogeneous in the RV (compared with LV walls) and were maximal in the mid part of the RV free wall (peak systolic SR: -2.8 +/- 0.7 s(-1), systolic epsilon -45% +/- 13%). The RV inferior wall showed homogeneous but lower longitudinal SR and epsilon values. The LV systolic and diastolic SR and epsilon values were higher for deformation in the radial direction compared with the longitudinal direction (radial peak systolic SR: 3.7 +/- 0.9 s(-1), radial systolic epsilon 57% +/- 11%; P <.0001). The interobserver variability for radial systolic epsilon and SR was 10.3% and 13.1%, respectively. CONCLUSION: Ultrasound-based Strain SR/epsilon imaging is a practical, reproducible clinical technique, which allows the calculation of regional longitudinal and radial deformation from both LV and RV segments. The combination of regional SR/epsilon indices and the timing of specific systolic or diastolic regional events may offer a new noninvasive approach to quantifying regional myocardial function in congenital and acquired heart disease in children.

Adolescent↗

PubMed2002

Can strain rate and strain quantify changes in regional systolic function during dobutamine infusion, B-blockade, and atrial pacing--implications for quantitative stress echocardiography.

BACKGROUND: We investigated the ability of ultrasonic strain rate (SR) and strain (epsilon) to quantify the changes in normal myocardial function at varying inotropic states and heart rates (HR) in an attempt to determine whether these new regional function indices are potentially robust enough to quantitate stress echocardiography. METHODS AND RESULTS: Twenty closed-chest pigs underwent incremental atrial pacing (AP: 120-180/min, n = 7), dobutamine infusion (DI: 2.5-20 microg/kg/min, n = 7) or esmolol infusion with subsequent pacing (EI: 0.5 +/- 0.15 mg/kg/min with pacing 120-180/min, n = 6). Radial deformation of the left ventricular posterior wall was interrogated using the parasternal short-axis view to derive regional systolic SR and epsilon values. At baseline SR and epsilon averaged 5.0 +/- 0.4 s(-1) and 60% +/- 4%, respectively. SR remained unchanged during AP and increased linearly with DI (at 2.5 microg/kg/min = 6.2 +/- 0.3 s(-1), P <.05 vs baseline; at 20 microg/kg/min = 9.9 +/- 0.7 s(-1), P <.0001 vs baseline), whereas EI resulted in a constant decrease of 30% +/- 4% in SR (P <.05). SR and left ventricular dP/dt(MAX) correlated linearly over the induced change in inotropic states and HR (r = 0.82; P <.0001). Conversely, epsilon values decreased during AP (at 180/min = 36% +/- 2%, P <.001). During DI, epsilon initially increased at 2.5 and 5 microg/kg/min (at 5 microg/kg/min = 77% +/- 6%, P <.05) and decreased for higher doses because of increasing HR. EI resulted in a decrease of 30% +/- 4% in epsilon with a further decrease during subsequent pacing. epsilon correlated linearly with left ventricular ejection fraction (r = 0.87; P <.0001). CONCLUSION: Both SR and epsilon can quantify the changes in myocardial function during a range of inotropic challenges and over the range of physiologic HRs encountered during clinical stress echocardiography. SR may reflect regional contractile function, whereas epsilon reflects changes in ventricular geometry. This study would suggest that for quantitative stress echocardiography SR is better in quantification of changes in contractile function being relatively independent of HR.

Adrenergic beta-Antagonists↗

PubMed2002

Can changes in systolic longitudinal deformation quantify regional myocardial function after an acute infarction? An ultrasonic strain rate and strain study.

OBJECTIVES: The aim of this study was to evaluate the additional value of ultrasonic strain rate and strain to myocardial velocity in the identification and quantification of regional asynergy after an acute myocardial infarction (MI). METHODS: Forty patients (59 +/- 13 years) were investigated 3 +/- 2 days after a first infarction and compared with 14 age-matched controls with normally contracting segments (group A, n = 146). Longitudinal myocardial velocities, strain rate (SR) and strain (epsilon) were postprocessed from basal, mid, and apical segments interrogated using apical views. In a subset of patients with coronary angiograms (n = 24), myocardial segments were divided into 3 groups: normally contracting segments supplied by a normal coronary artery (group B1), normally contracting segments supplied by a diseased coronary artery (group B2), and segments with abnormal motion (group B3). Velocities were decreased in patients with myocardial infarction (MI) (P <.05 vs controls) but failed to accurately differentiate normally from abnormally contracting segments. At the opposite end, systolic SR and epsilon decreased significantly with segmental asynergy severity and could identify infarct-involved segments (group B3) with a sensitivity/specificity of 85% (systolic SR and epsilon cutoff values of -0.8 s(-1) and -13%, respectively). CONCLUSION: Strain rate and strain can better assess segmental dysfunction severity than myocardial velocities alone after an acute MI.

Aged↗

PubMed2002

Two-dimensional ultrasonic strain rate measurement of the human heart in vivo.

A study is presented in which the feasibility of two-dimensional strain rate estimation of the human heart in vivo has been demonstrated. To do this, ultrasonic B-mode data were captured at a high temporal resolution of 3.8 ms and processed off-line. The motion of the RF signal patterns within the two-dimensional sector image was tracked and used as the basis for strain rate estimation. Both axial and lateral motion and strain rate estimates showed a good agreement with the results obtained by more established, one-dimensional techniques.

Adult↗

PubMed2002

Myocardial function defined by strain rate and strain during alterations in inotropic states and heart rate.

For porcine myocardium, ultrasonic regional deformation parameters, systolic strain (epsilon(sys)) and peak systolic strain rate (SR(sys)), were compared with stroke volume (SV) and contractility [contractility index (CI)] measured as the ratio of end-systolic strain to end-systolic wall stress. Heart rate (HR) and contractility were varied by atrial pacing (AP = 120-180 beats/min, n = 7), incremental dobutamine infusion (DI = 2.5-20 microg. kg(-1). min(-1), n = 7), or continuous esmolol infusion (0.5 mg. kg(-1). min(-1)) + subsequent pacing (120-180 beats/min) (EI group, n = 6). Baseline SR(sys) and epsilon(sys) averaged 5.0 +/- 0.4 s(-1) and 60 +/- 4%. SR(sys) and CI increased linearly with DI (20 microg. kg(-1). min(-1); SR(sys) = 9.9 +/- 0.7 s(-1), P < 0.0001) and decreased with EI (SR(sys) = 3.4 +/- 0.1 s(-1), P < 0.01). During pacing, SR(sys) and CI remained unchanged in the AP and EI groups. During DI, epsilon(sys) and SV initially increased (5 microg. kg(-1). min(-1); epsilon(sys) = 77 +/- 6%, P < 0.01) and then progressively returned to baseline. During EI, SV and epsilon(sys) decreased (epsilon(sys) = 38 +/- 2%, P < 0.001). Pacing also decreased SV and epsilon(sys) in the AP (180 beats/min; epsilon(sys) = 36 +/- 2%, P < 0.001) and EI groups (180 beats/min; epsilon(sys) = 25 +/- 3%, P < 0.001). Thus, for normal myocardium, SR(sys) reflects regional contractile function (being relatively independent of HR), whereas epsilon(sys) reflects changes in SV.

Adrenergic beta-Antagonists↗