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Biomedical subjects

Enrique Vallejo

Publications and source records attributed to Enrique Vallejo.

6 recordsLinked to original sources
PubMed2007

Myocardial perfusion and ventricular function assessed by SPECT and Gated-SPECT in end-stage renal disease patients before and after renal transplant.

BACKGROUND: Cardiovascular disease is a major cause of morbidity and mortality in end-stage renal disease (ESRD). Renal transplant is known to improve left ventricle hypertrophy and systolic dysfunction in selected groups of patients. METHODS: We assessed myocardial perfusion, wall motion and functional parameters by single photon emission computed tomography (SPECT) and Gated-SPECT in 30 consecutive ESRD patients with normal coronary angiograms before and after renal transplantation. RESULTS: Uremic cardiomyopathy improved significantly after the transplant. The proportion of patients with angina decreased from 26 to 0%; the frequency of cardiomegaly decreased from 57 to 20% (p <0.01); the frequency of segments with perfusion defects decreased from 42.7 to 10.2% (p <0.001); the proportion of patients with low left ventricular ejection fraction (LVEF) dropped from 53.3 to 20% (p <0.001); and mean LVEF increased from (48.0 +/- 9.7% to 58.2 +/- 8.2%). Similarly, the proportion of segments showing systolic wall thickening, hypokinesia and dyskinesia also decreased significantly after renal transplant (p <0.01). CONCLUSIONS: Uremic cardiomyopathy may be potentially reversible in patients with normal angiographic coronary arteries after renal transplant in a relatively short period of time. SPECT and Gated-SPECT are objective gateway methods to determine myocardial perfusion, hypokinesia, dyskinesia, and functional parameters (left ventricular ejection fraction and systolic wall thickening) and may be useful to establish diagnostic, coronariographic, prognostic, and therapeutic indications.

Adolescent↗
PubMedDate not supplied

Myocardial perfusion SPECT imaging in patients with myocardial bridging.

BACKGROUND: Although myocardial perfusion single photon emission computed tomography (SPECT) imaging is widely used to assess myocardial ischemia in patients with known or suspected coronary artery disease, only a few patients with myocardial bridging have been evaluated with nuclear techniques. Furthermore, it has been suggested that dipyridamole stress images might underestimate perfusion defects compared with exercise stress images. This study was done to determine the concordance of exercise stress SPECT images with that obtained by dipyridamole stress SPECT images as a means of detecting ischemia in patients with myocardial bridging. METHODS AND RESULTS: Sixteen consecutive patients with angina and normal arteries but myocardial bridging of the left anterior descending artery underwent rest-exercise stress SPECT imaging. Within 2 weeks after angiograms were obtained, only dipyridamole stress images were repeated. The mean angiographic systolic occlusion within the myocardial bridges was 73% +/- 10%. Overall, the prevalence of an abnormal scan was no different in patients who underwent exercise stress myocardial perfusion imaging (MPI) as compared with patients who underwent dipyridamole stress MPI (14/16 [88%] vs 13/16 [81%], respectively; P = .953). Exercise stress MPI showed a higher stress score than dipyridamole stress MPI, but the difference did not reach statistical significance (7.5 +/- 3.3 vs 6 +/- 2.7, P = .147). The strength of agreement among exercise stress MPI and dipyridamole stress MPI studies was good (kappa = 0.765; 95% CI, 0.318 to 1.211; P < .05). CONCLUSIONS: Cardiac SPECT studies can be used effectively for assessing ischemia in patients with angina and myocardial bridging. The evaluation of myocardial perfusion with dipyridamole stress SPECT imaging showed a good agreement with exercise stress SPECT imaging for the detection of ischemia in this group of patients.

Coronary Vessel Anomalies↗
PubMedDate not supplied

Variability of serial same-day left ventricular ejection fraction using quantitative gated SPECT.

BACKGROUND: The accuracy of quantitative gated single photon emission computed tomography (SPECT) (QGS) and the potential limitations for estimation of left ventricular ejection fraction (LVEF) have been extensively evaluated. However, few studies have focused on the serial variability of QGS. This study was conducted to assess the serial variability of QGS for determination of LVEF between 2 sequential technetium 99m sestamibi-gated SPECT acquisitions at rest in both healthy and unhealthy subjects. METHODS AND RESULTS: The study population consisted of 2 groups: group I included 21 volunteers with a low likelihood of CAD, and group II included 22 consecutive patients with documented CAD. Both groups underwent serial SPECT imaging. The overall correlation between sequential images was high (r = 0.94, SEE = 5.3%), and the mean serial variability of LVEF was 5.15% +/- 3.51%. Serial variability was lower for images with high counts (3.45% +/- 3.23%) than for images with low counts (6.85% +/- 3.77%). The mean serial variability was not different between normal and abnormal high-dose images (3.0% +/- 1.56% vs 3.9% +/- 2.77%). However, mean serial variability for images derived from abnormal low-dose images was significantly greater than that derived from normal low-dose images (9.6% +/- 2.22% vs 3.1% +/- 2.12%, P <.05). CONCLUSIONS: Although QGS is an efficacious method to approximate LVEF values and is extremely valuable for incremental risk stratification of patients with coronary artery disease, it has significant variability in the estimation of LVEF on serial images. This should be taken into account when used for serial evaluation of LVEF.

Adult↗
PubMedDate not supplied

[The future of PET in cardiology].

Positron emission tomography (PET) is an intrinsically quantitative method that provides an approach for the clinical cardiologist and cardiovascular researchers to evaluate the heart noninvasively. The ability to label biomolecules with positron-emiting radioisotopes, without disturbing their physiological properties, offers the opportunity to prove and quantify coronary blood flow, myocardial metabolism, and the alterations that occur with disease states. However, the major drawback prohibiting implementation of PET imaging in clinical routine is the limited availability of PET equipment and its greater cost per study. In order to enhance cost savings and resource efficiency in clinical practice, PET studies should be limited to those patients with equivocal studies by other imaging modalities or to define areas of potential viability and improve decisions for recommending coronary bypass grafting or cardiac transplantation. The combined data of multiple investigators suggest that 18-FDG-SPECT imaging may become the protocol of choice for determining myocardial viability because of its increased availability and cost-effectiveness as compared to PET.

Coronary Circulation↗
PubMedDate not supplied

[Assessment of postinfarction patients with nuclear techniques].

Residual myocardial ischemia and left ventricular systolic dysfunction are the major determinants of a patient's prognosis after myocardial infarction. Therefore, left ventricular function and residual ischemia should be evaluated in all patients before release. Coronary angiography should be performed in uncomplicated myocardial infarction patients with significant ischemia or left ventricular dysfunction. In these cases angiography must be performed to determine if coronary arteries are suitable for revascularization before performing a test of myocardial viability. Several radionuclide approaches are currently available for the clinical evaluation of patients after myocardial infarction. There is growing and consistent evidence that the scintigraphic approaches are the most sensitive technique to investigate the presence of ischemia or tissue viability and also to provide an accurate and reproducible evaluation of the left ventricular function. Most importantly, radionuclide evaluation in these patients provide valuable prognostic information. However, the number of patients with malignant arrhythmia's detected with routine evaluation is lower at this time. In several reports neuroadrenergic imaging evaluation with I-123-MIBG was predictive of sudden death. In consequence, it has been proposed that cardiac SPECT images with I-123-MIBG may provide important prognostic information in patients with uncomplicated myocardial infarction. Therefore it is not surprising that the incorporation of new radionuclide techniques may improve the evaluation of patients after myocardial infarction.

Humans↗