James A. Arrighi

Myocardial blood-flow response during mental stress in patients with coronary artery disease

Positron emission tomography was used to quantify changes in myocardial blood flow during mental stress in patients with and without coronary artery disease. Blunted augmentation of myocardial blood flow during mental stress was observed in regions without significant epicardial stenosis.

Simultaneous assessment of myocardial perfusion and function during mental stress in patients with chronic coronary artery disease.

BackgroundMental stress (MS) is an important provocateur of myocardial ischemia in many patients with chronic coronary artery disease. The majority of laboratory assessments of ischemia in response to MS have included measurements of either myocardial perfusion or function alone. We performed this study to determine the relationship between alterations in perfusion and ventricular function during MS.Methods and ResultsTwenty-eight patients with reversible perfusion defects on exercise or pharmacologic stress myocardial perfusion imaging (MPI) underwent simultaneous technetium 99m sestamibi single photon emission computed tomography (SPECT) MPI and transthoracic echocardiography at rest and during MS according to a mental arithmetic protocol. In all cases the MS study was performed within 4 weeks of the initial exercise or pharmacologic MPI that demonstrated ischemia. SPECT studies were analyzed visually with the use of a 13-segment model and quantitatively by semiautomated circumferential profile analysis. Echocardiograms were graded on a segmental model for regional wall motion on a 4-point scale. Of 28 patients, 18 (64%) had perfusion defects and/or left ventricular dysfunction develop during MS: 9 (32%) had myocardial perfusion defects develop, 6 (21%) had regional or global left ventricular dysfunction develop, and 3 (11%) had both perfusion defects and left ventricular dysfunction develop. The overall concordance between perfusion and function criteria for ischemia during MS was only 46%. Among 9 patients with MS-induced left ventricular dysfunction, 5 had new regional wall motion abnormalities and 4 had a global decrement in function. In patients with MS-induced ischemia by SPECT, the number of reversible perfusion defects was similar during both MS and exercise/pharmacologic stress (2.8 ± 2.0 vs 3.5 ± 1.8, P =.41). Hemodynamic changes during MS were similar whether patients were divided on the basis of perfusion defects or left ventricular dysfunction during MS.ConclusionsThese data indicate the feasibility of simultaneous assessment of perfusion and function responses during MS. Flow and function responses to MS are frequently not concordant. These data suggest that MS-induced changes in perfusion may represent a different phenomenon than MS-induced changes in left ventricular function (either globally or regionally).

Left ventricular diastolic function: Physiology, methods of assessment, and clinical significance

Diastole, that portion of the cardiac cycle that begins with isovolumic relaxation and ends with mitral valve closure, results in ventricular filling and involves both active (energy-dependent) and passive processes. The interactions between active processes (myocardial relaxation) that primarily influence early ventricular filling and passive processes, such as loading conditions, myocardial compliance, and valvular disease, are complex. Clinical methods to assess ventricular filling include cardiac catheterization, radionuclide angiography, and echocardiography. Any measurements of diastolic function must be made with an understanding of the determinants of ventricular filling and the limitations of the diagnostic test. Many cardiac disorders are characterized by elevated pulmonary venous pressures in the face of normal systolic ventricular function, which suggests a primary abnormality of diastolic function. Abnormalities in diastolic function have been observed in coronary artery disease, congestive heart failure (with and without systolic dysfunction), hypertrophic cardiomyopathy, hypertension, and in healthy elderly subjects. Identification of these abnormalities may be useful clinically, particularly in patients with symptoms of heart failure and normal systolic function. Data are not available to determine the optimal therapy for such patients, although evidence suggests that calcium channel blockers, beta blockers, and agents that reverse myocardial hypertrophy may be useful. This review briefly summarizes the physiology of diastole, the methods of clinical assessment of diastolic function, and the role of diastolic function in cardiovascular disease.

Effect of left ventricular function on the assessment of myocardial viability by technectium-99m sestamibi and correlation with positron emission tomography in patients with healed myocardial infarcts or stable angina pectoris, or both

The accuracy of technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) for the assessment of myocardial viability in patients with coronary artery disease and left ventricular (LV) dysfunction is not defined completely. This study determines whether the performance of Tc-99m sestamibi SPECT for viability detection differs between patients with mild-to-moderate coronary artery disease. Patients with regional and/or global LV dysfunction were separated into 2 groups on the basis of LV ejection fraction (EF) at rest: group 1 (LVEF > 25%, mean 36 +/- 6%, n = 9), and group 2 (LVEF < or = 25%, mean 17 +/- 5%, n = 11). All patients underwent semiquantitative Tc-99m sestamibi SPECT and positron emission tomography (PET) at rest with N-13 ammonia and F-18 fluorodeoxyglucose. The overall regional concordance of SPECT and PET for viability detection was 89% in group 1 and 78% in group 2 (p = 0.002). Discordance in group 2 was almost exclusively due to PET viable and/or SPECT nonviable regions. In regions with hypoperfusion at rest by PET, concordance was 78% in group 1 and only 64% in group 2 (p = 0.0015). In regions with reduced perfusion and relatively increased metabolic activity (flow: metabolism mismatch), Tc-99m sestamibi SPECT identified 88% of regions in group 1 as viable, but only 42% of regions in group 2 (p = 0.002). Thus, while Tc-99m sestamibi semiquantitative SPECT at rest shows a good concordance with PET for the detection of myocardial viability in patients with coronary artery disease with mild-to-moderate LV dysfunction, it may underestimate myocardial viability in patients with severe LV dysfunction, particularly in those patients with hypoperfusion at rest as assessed by PET.

Reverse redistribution: Is it clinically relevant or a washout?

The term reverse redistribution generally refers to a pattern characterized by the appearance of a worsening or new perfusion defect on thallium-201 redistribution imaging when compared with the stress image. More recently, the term has been applied to thallium imaging with resting reinjection and to imaging with technetium99m-based tracers. Although this phenomenon was initially reported nearly 20 years ago,l, 2 the pathophysiologic mechanisms and clinical significance remain poorly understood in all but a few clinical circumstances. As such, clinicians remain confused with regard to the interpretation of studies that manifest this finding. The reasons for the persistent confusion around reverse redistribution are revealed in part by examining the literature over the past two decades. In particular, study methodology has been quite variable. Most studies have been performed with stress-redistribution thallium scintigraphy. Others studies have been performed with rest-redistribution or stress-reinjection thallium imaging, whereas other recent reports have extended the term to include technetium-99m-based tracers. Instrumentation is another source of variability, with reports of this phenomenon in both planar and single-photon emission computed tomography (SPECT) modalities. Perhaps the greatest source of variability is in the patient populations studied. Examination of the literature therefore may be best accomplished by reducing this variability by grouping studies according to one of these parameters. The most clinically relevant examination is probably that which is based on the patient population studied.

Myocardial viability: Seeking relevance and redefinition

ConclusionsMore than any other discipline, nuclear cardiology has contributed to understanding of myocardial viability, including the concepts of hibernation and stunning. It must be recognized, however, that these concepts are used as models to drive the process of scientific inquiry. These models may describe components of the pathophysiology of ventricular dysfunction in CAD. Integration of the models of hibernation and stunning may represent the next step toward a more complete understanding of how CAD causes ventricular dysfunction. As such, we are now poised to redirect the field of viability assessment. Although the development of improved instrumentation, new tracers, and better software are important, the areas of investigation that will have the most significant effect on cardiology as a whole are those that will elucidate the pathophysiologic components of LV dysfunction in CAD. The knowledge can then be applied to clinical processes such as viability assessment, with attention to how new techniques affect prognosis and cost of health care. The nuclear imaging community should strive to develop techniques that are complementary to “competing” technologies such as magnetic resonance imaging and echocardiography, providing incremental information. Significant contributions to these lines of investigation will require cooperative studies to achieve adequate statistical power, including collaboration with the PET community. With studies addressing both the pathophysiology and the impact on clinical outcomes of myocardial viability and its assessment, the nuclear cardiology community will have much to contribute to our understanding of CAD.

Nuclear cardiology in everyday practice

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J. Candell-Riera and D. Ortega-Alcalde, Editors, Nuclear Cardiology in Everyday Practice, Klewer Academic Publishers (1994).

Read more and get great! Thats what the book enPDFd nuclear cardiology in everyday practice will give for every reader to read this book. This is an on-line book provided in this website. Even this book becomes a choice of someone to read, many in the world also loves it so much. As what we talk, when you read more every page of this nuclear cardiology in everyday practice, what you will obtain is something great.