Adenosine myocardial perfusion imaging.

Adenosine myocardial perfusion imaging is useful in diagnosis of coronary artery disease (CAD) and risk assessment in patients who have exercise limitations. As a pharmacologic stressor, adenosine acts on two cell-surface purine receptors, A1 and A2. Activation of A2 receptors cause coronary vasodilation.

Sequential dual-isotope SPECT imaging with thallium-201 and technetium-99m-sestamibi.

Unlabelled: This study examined the results of sequential SPECT dual-isotope imaging with 201Tl and 99mTc-sestamibi in 148 patients, 114 of whom also had coronary angiography and 34 had < 5% pretest probability for coronary artery disease (CAD).

Methods: Stress thallium/rest sestamibi was used in 82 patients and rest thallium/stress sestamibi in 66 patients. Coronary angiography showed that 17 patients had no CAD, 27 patients had one-vessel CAD, 41 patients had two-vessel CAD and 29 patients had three-vessel CAD.

Comparison of the treadmill exercise score and single-photon emission computed tomographic thallium imaging in risk assessment.

Background: This study compared the prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging with that of treadmill exercise score in medically treated patients with coronary artery disease (CAD).

Methods And Results: The treadmill exercise score was derived from exercise duration, degree of ST segment depression, and the treadmill anginal index. There were 121 patients with no CAD and 316 patients with angiographically defined CAD (> or = 50% diameter stenosis of one or more vessels).

Pharmacologic stress testing: mechanism of action, hemodynamic responses, and results in detection of coronary artery disease.

Pharmacologic stress testing may be used in the diagnosis of coronary artery disease and risk assessment. The stress agents may be divided into those that produce primary coronary vasodilation (dipyridamole, adenosine, or adenosine triphosphate) and those that produce secondary vasodilation as a result of increase in myocardial oxygen demand (dobutamine and arbutamine). Assessment of myocardial perfusion and function can be made by single-photon imaging, positron emission tomography, two-dimensional echocardiography, magnetic resonance imaging, and contrast angiography.

Cardiovascular applications of fluorocarbons: current status and future direction--a critical clinical appraisal.

Alteration of normal blood flow to the heart may result in myocardial ischemia or infarction. Perfluorochemical emulsions offer a potential means to improve oxygenation of the heart during periods of hypoxia. The small particle size and linear disassociation curve of perfluorochemicals may result in greater oxygen delivery than blood particularly in severely diseased or damaged atherosclerotic vessels.

Age- and sex-related differences in the use of coronary angiography in patients undergoing adenosine SPECT thallium imaging.

Background: Recent reports suggest sex-related differences in the management of patients with coronary artery disease.

Methods: This study examined the pattern of use of coronary angiography in 535 patients initially referred for adenosine single photon emission computed tomography (SPECT) thallium imaging.

Results: Coronary angiography was carried out more often in patients under 70 years of age than those over 70 years of age [107 out of 322 (33%) versus 50 out of 213 (23%), P < 0.

Simultaneous assessment of left ventricular perfusion and function with technetium-99m sestamibi after coronary artery bypass grafting.

This study examined the left ventricular perfusion and EF by using simultaneous SPECT and first-pass radionuclide angiography with technetium 99m sestamibi in 95 patients after uncomplicated coronary artery bypass grafting. The patients were divided into those with normal EF and no previous myocardial infarction before surgery (group 1, n = 57), and those with abnormal EF or infarction (group 2, n = 38). The SPECT images were normal in 37 patients in group 1 and in 6 patients in group 2 (p < 0.

Ventricular tachycardia in patients without structural heart disease.

The existence of ventricular tachycardia in subjects without detectable heart disease has been recognized for more than half a century. These rhythms occur in younger individuals and account for about 5% of referrals to the electrophysiology service. In contrast, ventricular tachycardia in the setting of chronic ischemic heart disease occurs in an older age group and accounts for more than 90% of all referrals.

Study of myocardial infarct remodeling by single-photon emission computed tomographic imaging.

Left ventricular (LV) remodeling after Q-wave anterior acute myocardial infarction (AMI) was examined with single-photon emission computed tomographic thallium imaging. Initial (after adenosine infusion) and 4-hour delayed reinjection images were obtained in 34 patients aged 65 +/- 12 years. Short-axis slices from the delayed images were quantitatively analyzed by measuring the outer and inner diameters, and wall thickness.

Simplified method for calculating aortic valve resistance: correlation with valve area and standard formula.

Aortic valve resistance (AVR) is a useful index to assess the severity of aortic stenosis. This study compared the standard method to calculate AVR with a simplified method based on the conventional approach for measuring vascular resistance: AVR = (peak-to-peak transaortic pressure gradient/(cardiac output*2.5))*80, where 80 is a conversion factor and 2.

Independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in coronary artery disease.

Objectives: The objective of this study was to examine the independent and incremental prognostic value of exercise single-photon emission computed tomographic (SPECT) thallium imaging in patients with angiographically defined coronary artery disease.

Background: Previous studies showed the importance of exercise thallium-201 in risk stratification. However, most of these studies used planar imaging techniques.

Ventricular coupling via the pericardium: normal versus tamponade.

Objective: The aim was to examine how regional variations in pericardial pressure affect the mechanical coupling between the ventricles.

Methods: Canine hearts from 14 dogs (14.5-18 kg) were removed and placed in cold cardioplegia solution.

The role of nuclear imaging in ischemic heart disease.

Assessment of myocardial perfusion during exercise and pharmacologic stress testing is an important factor in the detection of coronary artery disease and in risk assessment. Imaging techniques that examine myocardial perfusion and cellular integrity or myocardial metabolism flow mismatches aid in the detection of reversible causes of left ventricular dysfunction. These techniques are also helpful in managing patients after percutaneous transluminal coronary angioplasty or thrombolytic therapy.

The order of dilator-constrictor administration affects stenotic hemodynamic responses.

This study tested the hypothesis that, due to intraluminal pressure changes, the order of constrictor-dilator administration alters stenotic hemodynamic responses. Canine carotid arteries were perfused with a physiologic salt solution under constant pressure (100 mm Hg). An intraluminal stenosis partially obstructed the arteries.

Variations in the size of the ischemic myocardium due to differences in the normal file.

The myocardial thallium concentration is different during pharmacologic than exercise stress testing due to differences in coronary blood flow and cardiac output. These differences may affect the quantitative measurement of the size of ischemic myocardium if a stress-specific normal file is not used. This study examined this concept in 34 patients with isolated left anterior descending coronary artery disease.

Identification of extensive coronary artery disease in women by exercise single-photon emission computed tomographic (SPECT) thallium imaging.

Objectives: The aim of this study was to examine the ability of exercise single-photon emission computed tomographic (SPECT) thallium imaging to identify high risk women with left main or three-vessel coronary artery disease using a stepwise discriminant analysis.

Background: Previous studies have used statistical methods to identify high risk men with coronary artery disease. Only limited data are available in women.

Contribution of each wall to biventricular function.

Objective: Common muscle fibres encircle both ventricles and the ventricles share a common septal wall. This close anatomical association suggests that regional ischaemia and structural integrity may alter systolic function in both the right and the left ventricle. To examine this possibility, we investigated the contribution of each wall to biventricular function.

Effects of cardiomyoplasty on biventricular function in canine chronic heart failure.

Dynamic cardiomyoplasty, the use of skeletal muscle to assist the heart, is a new therapy for the treatment of heart failure. However, the effects of cardiomyoplasty on biventricular function and the synchrony of ventricular contraction are not fully known. We assessed the efficacy of latissimus dorsi muscle (LDM) dynamic cardiomyoplasty in a chronic model of biventricular failure.

Identification of high-risk patients with left main and three-vessel coronary artery disease by adenosine-single photon emission computed tomographic thallium imaging.

The purpose of this study was to examine the ability of SPECT imaging with thallium-201 during adenosine-induced coronary hyperemia to detect high-risk patients with left main or three-vessel CAD. There were 339 patients: 102 with either left main or three-vessel CAD (group 1) and 237 with no CAD, one-, or two-vessel disease (group 2). By means of univariate analysis, several variables were found to differ between groups 1 and 2: Q wave myocardial infarction (35% vs 25%, p < 0.

ICD data storage: value in arrhythmia management.

Sophisticated diagnostic information is provided by the latest generation of implantable defibrillators. The success of therapy and the type of therapy successful in terminating ventricular arrhythmias is provided by interrogating the ICD device. In addition, R to R interval information can be retrieved.

Effect of adenosine on coronary blood flow and its use as a diagnostic test for coronary artery disease.

Myocardial perfusion imaging during adenosine induced coronary hyperaemia is a highly sensitive method for diagnosing coronary artery disease. Most perfusion defects reflect heterogeneity in coronary blood flow in the territories of normal and diseased coronary arteries. Myocardial ischaemia can occur, however, due to subendocardial hypoperfusion and coronary artery steal.

Identification of high-risk patients with left main and three-vessel coronary artery disease using stepwise discriminant analysis of clinical, exercise, and tomographic thallium data.

This large-scale study examined the ability of stepwise discriminant analysis of clinical, exercise, and thallium tomographic data to detect high-risk patients with three-vessel or left main disease. There were 834 patients, 229 with three-vessel or left main disease (group 1) and 605 (group 2) with either two-vessel disease (n = 236), one-vessel disease (n = 195), or no coronary artery disease (n = 174). The two groups were different in age, exercise heart rate, ST segment depression during exercise, exercise systolic blood pressure, abnormal thallium scans, reversible perfusion defects, extent of thallium abnormality, number of vascular territories with perfusion abnormalities, left ventricular cavity dilatation, and increased lung thallium uptake.