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Biomedical subjects

Mark I Travin

Publications and source records attributed to Mark I Travin.

10 recordsLinked to original sources
PubMed2006

Specimen processing time and measurement of total insulin-like growth factor-I (IGF-I), free IGF-I, and IGF binding protein-3 (IGFBP-3).

BACKGROUND: An increasing number of epidemiologic studies are investigating the relationship between serum levels of insulin-like growth factor-I (IGF-I) and IGF binding proteins (IGFBPs) and risk of cancer, cardiovascular disease, and other diseases. However, little is known regarding the effects of blood specimen processing time on measured levels of total and free IGF-I, and on IGFBP-3, the major binding protein. DESIGN: Two serum separation tubes were collected from each of 12 subjects. One tube was centrifuged as soon as possible following blood collection (a mean of 47 min; range=30-80 min), and serum aliquots were placed into -70 degrees C storage either shortly after centrifugation, or following 2, 4, 10, or 24 h at ambient temperature (measured from the time of blood draw). The second serum separation tube was maintained at ambient temperature for 24h before centrifugation and freezing. Total IGF-I, free IGF-I, and IGFBP-3 levels were determined using commercial enzyme linked immunosorbent assays (ELISAs) commonly employed in epidemiologic studies. The effects of time until centrifugation and freezing on seroassay results were evaluated using generalized estimating equation (GEE) linear regression models and Spearman correlation. RESULTS: Total IGF-I and IGFBP-3 levels did not vary significantly with the amount of time at ambient temperature following centrifugation, even up to 24 h, in blood specimens that were centrifuged soon after collection (all pchi2). However, free IGF-I levels increased significantly with increasing time intervals between centrifugation and freezing in these same specimens (ptrend <0.001). Total IGF-I/IGFBP-3 molar ratio, a crude measure of free IGF-I levels, showed no clear association. In blood specimens that were not centrifuged for 24h, total IGF-I, free IGF-I, and IGFBP-3 were each significantly elevated (each pchi2) compared with results in blood specimens that were centrifuged and frozen soon after collection, whereas the total IGF-I/IGFBP-3 molar ratio was decreased pchi2. Nonetheless, all total IGF-I, free IGF-I, IGFBP-3, and total IGF-I/IGBFBP-3 molar ratio values altered by delays in processing were highly correlated with the values in specimens processed as soon as possible (all Spearman rank correlation coefficients 0.84). CONCLUSIONS: Total IGF-I and IGFBP-3 can be fairly stably measured in serum with commonly used commercial assays regardless of the interval between blood collection and freezing, up to at least 24 h, as long as centrifugation and serum aliquoting take place shortly after blood collection. Free IGF-I levels, however, increase steadily with the time interval until freezing, even if serum separation has been completed soon after blood collection. Because the altered serum values are highly correlated with the referent values, analysis of total IGF-I, free IGF-I, IGFBP-3, and total IGF-I/IGFBP-3 molar ratio data by quartile might help mitigate concerns regarding the effects of delays in processing time.

Adult↗
PubMed2006

A case of Takotsubo cardiomyopathy mimicking an acute coronary syndrome.

BACKGROUND: A 71-year-old woman presented with severe chest pain after an episode of acute emotional distress. Her serum levels of cardiac enzymes were slightly elevated and electrocardiography revealed anterior ST-segment elevations. Significant coronary stenoses were excluded. A left ventriculogram revealed apical ballooning and a hypercontractile basal segment. INVESTIGATIONS: Serum cardiac enzyme measurements, echocardiography, coronary angiography and left ventriculography. DIAGNOSIS: Takotsubo cardiomyopathy. MANAGEMENT: Treatment with beta-blockers, aspirin, angiotensin-converting-enzyme inhibitors, and intravenous diuretics.

Aged↗
PubMed2005

Assessment of myocardial viability.

The prevalence of left ventricular (LV) dysfunction and resultant congestive heart failure is increasing. Patients with this condition are at high risk for cardiac death and usually have significant limitations in their lifestyles. Although there have been advances in medical therapy resulting in improved survival and well being, the best and most definitive therapy, when appropriate, is revascularization. In the setting of coronary artery disease, accounting for approximately two thirds of cases of congestive heart failure, LV dysfunction often is not the result of irreversible scar but rather caused by impairment in function and energy use of still viable-myocytes, with the opportunity for improved function if coronary blood flow is restored. Patients with LV dysfunction who have viable myocardium are the patients at highest risk because of the potential for ischemia but at the same time benefit most from revascularization. It is important to identify viable myocardium in these patients, and radionuclide myocardial scintigraphy is an excellent tool for this. Single-photon emission computed tomography perfusion scintigraphy, whether using thallium-201, Tc-99m sestamibi, or Tc-99m tetrofosmin, in stress and/or rest protocols, has consistently been shown to be an effective modality for identifying myocardial viability and guiding appropriate management. Metabolic imaging with positron emission tomography radiotracers frequently adds additional information and is a powerful tool for predicting which patients will have an improved outcome from revascularization, including some patients referred instead for cardiac transplantation. Other noninvasive modalities, such as stress echocardiography, also facilitate the assessment of myocardial viability, but there are advantages and disadvantages compared with the nuclear techniques. Nuclear imaging appears to require fewer viable cells for detection, resulting in a higher sensitivity but a lower specificity than stress echocardiography for predicting post-revascularization improvement of ventricular function. Nevertheless, it appears that LV functional improvement may not always be necessary for clinical improvement. Future directions include use of magnetic resonance imaging, as well as larger, multicenter trials of radionuclide techniques. The increasing population of patients with LV dysfunction, and the increased benefit afforded by newer therapies, will make assessment of myocardial viability even more essential for proper patient management.

Clinical Trials as Topic↗
PubMed2004

Stress radionuclide myocardial perfusion imaging detects more residual ischemia than stress echocardiography following acute myocardial infarction.

OBJECTIVES: This investigation sought to compare the abilities of stress radionuclide myocardial perfusion imaging and stress echocardiography to detect residual ischemia in patients following acute myocardial infarction (MI). BACKGROUND: Stress radionuclide myocardial perfusion imaging and stress echocardiography are both commonly used to assess patients (patients.) in the immediate post MI period. However, the relative value of these techniques in identifying post MI ischemia remains unclear. METHODS: Eighteen patients. underwent both dipyridamole radionuclide perfusion imaging and dobutamine stress echocardiography on the same day or on consecutive days, 3-7 days following uncomplicated acute MI. Pts. who had an acute percutaneous intervention were excluded. Images were reviewed with clinical information available, but blinded to the opposing modality, for perfusion defects, wall motion abnormalities (WMA), and evidence of ischemia (reversible defect(s) on perfusion imaging, worsening WMA on stress echocardiography). Of the 18 patients, 11 subsequently underwent cardiac catheterization. RESULTS: Perfusion imaging identified defects in 16 (89%) patients, of whom 15 (83% of total) were found to be ischemic. Stress echocardiography identified a fixed wall motion abnormality in 17 (94%) and ischemia in 8 (44%, p < 0.05 compared with perfusion imaging ischemia). Among 11 patients who underwent catheterization, there was a trend towards perfusion imaging identifying more ischemia in the territory of an obstructed (> or = 70%) vessel--100% (11/11) vs. 64% (7/11) for stress echocardiography (p = 0.09). CONCLUSION: In the immediate post-infarction period, dipyridamole stress radionuclide myocardial perfusion imaging more often shows evidence of residual ischemia than dobutamine stress echocardiography.

Adult↗
PubMed2002

Impact of diabetes on the risk stratification using stress single-photon emission computed tomography myocardial perfusion imaging in patients with symptoms suggestive of coronary artery disease.

BACKGROUND: Coronary artery disease can develop prematurely and is the leading cause of death among diabetics, making noninvasive risk stratification desirable. METHODS AND RESULTS: Patients with symptoms of coronary artery disease who were undergoing stress myocardial perfusion imaging (MPI) from 5 centers were prospectively followed (2.5+/-1.5 years) for the subsequent occurrence of cardiac death, myocardial infarction (MI), and revascularization. Stress MPI results were categorized as normal or abnormal (fixed or ischemic defects and 1, 2, or 3 vessel distribution). Of 4755 patients, 929 (19.5%) were diabetic. Patients with diabetes, despite an increased revascularization rate, had 80 cardiac events (8.6%; 39 deaths and 41 MIs) compared with 172 cardiac events (4.5%; 69 deaths and 103 MIs) in the nondiabetic cohort (P<0.0001). Abnormal stress MPI was an independent predictor of cardiac death and MI in both populations. Diabetics with ischemic defects had an increased number of cardiac events (P<0.001), with the highest MI rates (17.1%) observed with 3-vessel ischemia. Similarly, a multivessel fixed defect was associated with the highest rate of cardiac death (13.6%) among diabetics. The unadjusted cardiac survival rate was lower for diabetic patients (91% versus 97%, P<0.001), but it became comparable once adjusted for the pretest clinical risk and stress MPI results. In multivariable Cox analysis, both ischemic and fixed MPI defects independently predicted cardiac death alone or cardiac death/MI. Diabetic women had the worst outcome for any given extent of myocardial ischemia. CONCLUSIONS: In this large cohort of diabetics undergoing stress MPI, the presence and the extent of abnormal stress MPI independently predicted subsequent cardiac events. Using stress MPI in conjunction with clinical information can provide risk stratification of diabetic patients.

Aged↗
PubMedDate not supplied

The prognostic value of ECG-gated SPECT imaging in patients undergoing stress Tc-99m sestamibi myocardial perfusion imaging.

BACKGROUND: The ability of stress radionuclide myocardial perfusion imaging to predict adverse cardiac events is well accepted. As left ventricular systolic function has also been shown to be an important prognostic indicator, the objective of this study was to determine whether electrocardiography (ECG)-gated single photon emission computed tomography (SPECT) functional data add additional power. METHODS AND RESULTS: In this study 3207 patients who underwent stress myocardial perfusion imaging with ECG gating, without early (</=60 days) revascularization, were studied. Subsequent nonfatal myocardial infarction and cardiac death were related to perfusion and ECG-gated SPECT ventricular function parameters. Cox proportional hazards regression analysis was used to evaluate the independent predictive value of these parameters, as well as their added utility over clinical and ECG parameters. Patients with abnormal perfusion images had an annual event rate of 5.1% compared with 1.6% for patients with normal images (P <.001). An abnormal gated SPECT wall motion score was associated with an annual event rate of 6.1% compared with 1.6% for a normal score (P <.001), and an abnormal left ventricular ejection fraction was associated with an event rate of 7.4% compared with 1.8% for normal patients (P <.001). Abnormal ECG-gated SPECT results worsened outcome in both patients with normal perfusion images and those with abnormal perfusion images. Cardiac death was predicted by the number of territories with a perfusion defect and an abnormal ejection fraction, whereas myocardial infarction was predicted by the number of territories with a perfusion defect but not by ejection fraction. CONCLUSIONS: Ventricular function data from ECG-gated SPECT add important prognostic value to data obtained from perfusion imaging alone in predicting adverse cardiac events.

Adult↗
PubMedDate not supplied

Visual assessment of left ventricular perfusion and function with electrocardiography-gated SPECT has high intraobserver and interobserver reproducibility among experienced nuclear cardiologists and cardiology trainees.

BACKGROUND: Stress electrocardiography (ECG)-gated single photon emission computed tomography (SPECT) for assessment of left ventricular perfusion and function improves the confidence of interpretation and enhances specificity for detection of coronary artery disease. The reproducibility of visual interpretation of ECG-gated SPECT images and the significance of training and experience have not been reported previously in a large series of consecutive patients. We evaluated both intraobserver and interobserver agreement of interpretation of ECG-gated SPECT images among 3 cardiology trainees and 3 experienced nuclear cardiologists from 3 institutions. METHODS AND RESULTS: Three nuclear cardiologists and 3 cardiology trainees who had fulfilled American College of Cardiology/American Society of Nuclear Cardiology Core Cardiology Training Symposium (ACC/ASNC COCATS) guidelines for level II training in nuclear cardiology independently evaluated 106 consecutive technetium 99m sestamibi SPECT images with ECG gating of either the stress or rest images. All cases were interpreted blindly, twice in random sequence, without clinical data. We assessed intraobserver and interobserver agreement for myocardial perfusion, left ventricular regional and global systolic function, and overall clinical impression, by means of percent agreement and Cohen's kappa statistic. Intraobserver agreement was good (82%-92%, kappa = 0.54-0.84) for assessment of myocardial perfusion, systolic function, and overall impression. Interobserver agreement was also good, ranging from 65% to 90% (kappa = 0.32-0.76), with better agreement found for assessment of function (77%-85%, kappa = 0.52-0.7) than for perfusion (65%-80%, kappa = 0.32-0.6). For all measures, there were no significant differences in reproducibility between nuclear cardiologists and cardiology trainees. CONCLUSIONS: Interpretation of ECG-gated SPECT images has high reproducibility and agreement among both nuclear cardiologists and cardiology trainees.

Electrocardiography↗
PubMedDate not supplied

I-123 MIBG imaging and heart rate variability analysis to predict the need for an implantable cardioverter defibrillator.

BACKGROUND: Iodine 123 metaiodobenzylguanidine (MIBG) imaging and heart rate variability (HRV) analysis were compared in patients with an implantable cardioverter defibrillator (ICD) who did and did not receive defibrillator discharges. Although the ICD has been shown to abort potentially fatal ventricular arrhythmias, identification of patients who most benefit from this device remains difficult. As the autonomic nervous system has been implicated in the genesis of these arrhythmias, we undertook a pilot study to evaluate local myocardial sympathetic innervation with the use of I-123 MIBG myocardial imaging, as well as central autonomic tone with the use of HRV, in patients with implantable defibrillators. Test results were correlated with the occurrence of ICD discharges. METHODS AND RESULTS: Seventeen patients with previously implanted defibrillators were studied. Of these, 10 had at least 1 appropriate device discharge for ventricular tachyarrhythmias, whereas 7 had no discharge. Patients with a discharge had a significantly lower I-123 MIBG heart-mediastinal tracer uptake ratio, higher I-123 MIBG defect scores, more extensive sympathetic denervation, and significantly reduced values for several HRV parameters, particularly those in the frequency domain. When combined, the I-123 MIBG heart-mediastinal ratio and HRV 5-minute low-frequency variables were highly predictive of defibrillator discharges. All patients with a heart-mediastinal ratio lower than 1.54 and 5-minute low frequency lower than 443 ms(2) had an ICD discharge (4/4), whereas no patient with an uptake ratio greater than 1.54 and 5-minute low frequency greater than 443 ms(2) did (0/3, P =.03). CONCLUSIONS: Cardiac autonomic assessment using a combination of myocardial scintigraphic and neurophysiologic techniques may help select patients who would most benefit from an implantable defibrillator by identifying those at increased risk for potentially fatal arrhythmias.

3-Iodobenzylguanidine↗