Aerospace medicine and biology: A continuing bibliography with indexes

This bibliography lists 138 reports, articles, and other documents introduced into the NASA scientific and technical information system in Jun. 1980

Doppler tissue imaging in ST-elevation myocardial infarction

Highly available, noninvasive and cost-effective, echocardiography remains a keystone in the evaluation of patients with coronary artery disease (CAD). Echocardiographic assessment of cardiac function at rest and during dobutamine stress has direct clinical implications. Conventional echocardiographic parameters however, are partly based on visual interpretation of cardiac motion, thereby subject to interobserver variability, especially in patients with poor image quality. As a complement, myocardial velocity imaging techniques such as Doppler tissue imaging (DTI) offer quantitative markers of cardiac function. In the present study, we explored the feasibility and diagnostic value of DTI in the evaluation of left and right ventricular function, the presence of inducible ischemia and myocardial viability in patients with ST-elevation myocardial infarction (STEMI). In 90 patients with STEMI (64 men and 26 women aged 65±13 years) echocardiography was performed at day 1, 5–7 days and 6 months after admission. At day 5–7, dobutamine stress echocardiography (DSE) with wall motion analysis (WMA) was performed, followed by coronary angiography within 24 hours. Using DTI, systolic, early and late diastolic myocardial velocities were recorded near the mitral annulus at 4 left ventricular (LV) sites, and near the tricuspid annulus in the right ventricular free wall. The myocardial performance index (MPI), a Doppler-based, combined measure of systolic and diastolic function, was calculated as the sum of the isovolumic time intervals divided by the ejection time derived from DTI at the 4 LV sites. Forty-one aged-matched healthy subjects served as controls. In patients with complete normalization of conventional parameters of LV function at follow-up, peak systolic as well as early diastolic LV myocardial velocities were significantly reduced compared with those in healthy subjects, possibly reflecting a residual subendocardial damage. Using peak systolic velocity in the right ventricular (RV) free wall as a marker of RV function, sensitivity and specificity of DTI in identifying patients with electrocardographic signs of RV infarction (ST-elevation in ECG lead V4R) were 89% and 71%, respectively. Furthermore, peak RV systolic velocities remained reduced in patients with RV infarction, even after resolution of ECG changes and were still evident at 6 months’ follow-up. Use of the MPI as a marker of ischemia during DSE was shown to be feasible, and although the majority of patients did not achieve an optimal level of stress, relative changes in MPI between rest and peak stress offered reasonable diagnostic properties, superior to those of WMA. Sensitivity and specificity for detection of left anterior descending, left circumflex and right coronary artery disease were 80% and 87%, 59% and 80% and 85% and 72%, respectively. Finally, we found that MPI during low-dose dobutamine infusion exhibits a specific pattern, similar to that of WMA, predicting late recovery of LV systolic function. In conclusion, the use of DTI during echocardiography at rest and during dobutamine stress is feasible and allows evaluation of LV and RV function in the acute as well as the late phase after a STEMI. Furthermore, changes in MPI derived from DTI during DSE identify patients with residual CAD and predict late recovery of LV function, independently of age, troponin level and time to reperfusion treatment

Comparison of stress dobutamine echocardiography and stress dobutamine gated myocardial SPECT for the detection of viable myocardium

BACKGROUND: We prospectively studied a group of patients with myocardial infarction (MI), who were candidates for surgical revascularization, to compare the efficacy of dobutamine gated myocardial SPECT with dobutamine stress echocardiography (DSE) for the detection of myocardial viability. MATERIALS AND METHODS: We investigated 224 segments from 14 patients with MI using resting echocardiography and low dose dobutamine stress echocardiography as well as resting, low and high dose dobutamine stress 99mTc-Sestamibi gated SPECT. RESULTS: In total, 13 men and 1 women with a mean age 54.57 years (range, 43 to 71 years) entered the study. Of the 125 dysfunctional segments, as assessed by ECG-gated examination, 53 (23.66% of total) were hypokinetic at rest, 64 (28.57% of total) were akinetic, and 8 (3.57% of total) were dyskinetic. The number of segments with resting wall motion abnormality (considered viable by low dose dobutamine ECG-gated examination) was significantly greater than those showing a contractile improvement in response to dobutamine in echocardiography (39.2% versus 32.8%, respectively, p < 0.05). In addition, in high dose ECG-gated examination, 42 of the 125 dysfunctional segments (33.6%) were viable. In general, the methods were well correlated. CONCLUSION: We found a good agreement between low dose dobutamine gated SPECT and stress dobutamine echocardiography for the detection of inotropic reserve in infarcted areas.

Aerospace Medicine and Biology: A continuing bibliography with indexes (supplement 291)

This bibliography lists 131 reports, articles and other documents introduced into the NASA scientific and technical information system in November 1986

Recovery of regional myocardial dysfunction after successful coronary angioplasty early after a non-Q wave myocardial infarction

More aggressive therapy has been suggested for patients who have a non-Q wave myocardial infarction (MI) because of the frequency of subsequent unstable angina, recurrent MI, and high mortality rate compared to patients with Q wave MI. The present study was undertaken to investigate the effect of coronary angioplasty on regional myocardial function of the infarct zone in patients with angina early after a non-Q wave MI. The study population consisted of 36 patients undergoing successful coronary angioplasty within 30 days of a non-Q wave MI, in whom sequential left ventricular angiograms of adequate quality were obtained before the initial procedure and at follow-up angiography. The global ejection fraction increased significantly from 60 +/- 9% to 67 +/- 6% (p = 0.0003). This significant increase in the global ejection fraction was primarily due to a significant improvement in the regional myocardial function of the infarct zone. The results of the present study show not only that ischemic attacks early after a non-Q wave MI may lead to prolonged regional myocardial dysfunction but more important that this depressed myocardium has the potential to achieve normal contraction after successful coronary angioplasty

Computer-aided detection of wall motion abnormalities in cardiac MRI

With the increasing prevalence and hospitalization rate of ischaemic heart disease, an explosive growth of diagnostic imaging for ischaemia is ongoing. Clinical decision making on revascularization procedures requires reliable viability assessment to assure long-term patient survival and to elevate cost effectiveness of the therapy and treatment. As such, the demand is increasing for a computer-assisted diagnosis (CAD) method for ischaemic heart disease that supports clinicians with an objective analysis of infarct severity, a viability assessment or a prediction of potential functional improvement before performing revascularization. The goal of this thesis was to explore novel mechanisms that can be used for CAD in ischaemic heart disease, particularly through wall motion analysis from cardiac MR images. Existing diagnostic treatment of wall motion analysis from cardiac MR relies on visual wall motion scoring, which suffers from inter- and intra-observer variability. To minimize this variability, the automated method must contain essential knowledge on how the heart contracts normally. This enables automatic quantification of regional abnormal wall motion, detection of segments with contractile reserve and prediction of functional improvement in stress.1. Bontius Stichting inz. Doelfonds beeldverwerking, 2. Foundation Imago, 3. ASCI research school, and 4. Library of the University of Leiden.UBL - phd migration 201

Myocardial ischaemia and post-systolic shortening

The assessment of regional wall motion is useful to identify myocardial ischaemia because wall motion abnormalities occur relatively upstream in the ischaemic cascade. Echocardiography is widely used for this, but the subjectivity of visual observation may hamper accurate evaluation. The analysis of myocardial velocity and strain by tissue Doppler and speckle tracking echocardiography has allowed the quantitative assessment of regional wall motion and facilitated the detection of subtle myocardial deformation that is diffi cult to identify by conventional methods, such as post-systolic shortening (PSS). PSS is de fined as myocardial shortening that occurs after end-systole (or aortic valve closure), and it is observed in the myocardium with regional contractile dysfunction. In experimental and clinical studies, it has been reported that the assessment of PSS is superior to that of conventional parameters such as wall thickening or peak systolic strain in detecting acute ischaemia and diagnosing coronary artery disease. Moreover, it has recently been found that PSS remains after recovery from brief ischaemia despite the rapid recovery of peak systolic strain. The assessment of PSS allows after-thefact recognition of myocardial ischaemic insults and is expected to be used for ischaemic memory imaging. In this review, the usefulness of the assessment of PSS for the diagnosis of acute ischaemia and ischaemic memory is demonstrated, and issues that need to be resolved for the widespread use of this assessment in the echocardiographic laboratory are discussed.This article has been accepted for publication in Heart, 2015 following peer review, and the Version of Record can be accessed online at http://dx.doi.org/10.1136/heartjnl-2013-305403