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M J Cramer

Publications and source records attributed to M J Cramer.

At least 19 recordsLinked to original sources
PubMed2003

Contrast-enhanced MRA and 3D visualization of pulmonary venous anatomy to assist radiofrequency catheter ablation.

In pulmonary vein isolation as a treatment for atrial fibrillation the proximal part of the pulmonary veins is catheterized. A protocol for preinterventional assessment of pulmonary vein anatomy was developed, based on contrast-enhanced magnetic resonance angiography (MRA) in combination with three-dimensional visualization to tailor periprocedural angiography. The results allow for assessment of the number, morphology, and location of the ostia of the pulmonary veins, as well as complicating anatomical variations, such as common trunks and aberrant courses.

Adult↗
PubMed1997

Comparison of thallium scintigraphy and positron emission tomography.

Assessment of tissue viability has become an important issue in recent years. Scintigraphic measurements have provided important diagnostic, therapeutic, and prognostic information in patients with myocardial dysfunction, who may improve in left ventricular function after revascularization. For detection of regional myocardial ischemia and viability, thallium 201 (201Tl) has been the most widely used tracer in single-photon scintigraphy. However, 201Tl scintigraphy may underestimate regional viability, especially after myocardial infarction. Positron emission tomography (PET) provides an advanced imaging technology that permits the accurate definition of regional tracer distribution. In combination with nitrogen (13N) ammonia, PET allows for the sensitive and specific detection of coronary artery disease. Several studies indicate the superiority of this approach in comparison with standard 201Tl tomographic (SPECT) imaging. In addition, regional blood flow can be accurately measured with 13N ammonia PET, and this approach can be employed in conjunction with pharmacologic stress imaging to quantify regional flow reserve. In combination with metabolic markers, such as fluorine 18 (18F) deoxyglucose, an indicator of glucose uptake, PET is capable of assessing myocardial viability. Furthermore, the PET approach may differentiate between various forms of cardiomyopathy. More studies are needed to define the cost-benefit ratio of both the 201Tl reinjection and the PET technique for the management of patients with coronary artery disease or cardiomyopathy.

Ammonia↗
PubMed1997

SPECT versus planar 99mTc-sestamibi myocardial scintigraphy: comparison of accuracy and impact on patient management in chronic ischemic heart disease.

A head-to-head comparison between 99mTc-sestamibi SPECT and planar myocardial imaging using dipyridamole low-level exercise stress was performed for the assessment of coronary artery disease (CAD) and for the impact on patient management in 78 patients (pts) who underwent coronary arteriography. Overall sensitivity and specificity for detection of CAD were 82% and 82% for SPECT, and 78% and 73% for planar imaging, respectively (both NS). Compared to planar imaging the sensitivity of SPECT imaging was significantly higher for detecting left anterior descending (p = 0.02) and left circumflex (p = 0.03) coronary artery disease. In predicting distally located stenoses, SPECT was significantly superior to planar imaging for the left circumflex artery (p = 0.025). Concordance analysis of perfusion status showed agreement in 308 of 390 (79%) of coronary flow regions both with respect to the presence or absence of perfusion and to the reversibility or irreversibility of defects (kappa = 0.60, SE 0.04). Stress-induced perfusion defects were significantly more detected by SPECT than by planar imaging (p < 0.001). Based on SPECT findings 31 pts were proposed for revascularization compared to 30 pts based on planar imaging (NS). Overall there was agreement in 65 (83%) pts regarding treatment strategy. We conclude that in a head-to-head comparison SPECT provided improved diagnostic value compared with planar imaging. However, with respect to patient treatment, the superiority of SPECT was not always translated into improved patient management.

Adult↗
PubMed1996

Listeria monocytogenes endocarditis in a patient with an aortic prosthetic valve.

Patients with prosthetic cardiac valves have an increased risk of developing bacterial endocarditis. The causative micro-organism in bacterial endocarditis may be a guide to the portal of entry. In this case report, we describe a patient with a prosthetic cardiac valve who suffered from recurrent endocarditis with different micro-organisms from the gastrointestinal tract.

Adenocarcinoma↗
PubMed1996

Comparison of adenosine and high-dose dipyridamole both combined with low-level exercise stress for 99Tcm-MIBI SPET myocardial perfusion imaging.

Intravenously administered adenosine and high-dose dipyridamole, both combined with low-level exercise stress, were compared in a head-to-head fashion using 99Tcm-methoxyisobutyl isonitrile (99Tcm-MIBI) single photo emission tomography (SPET) myocardial perfusion imaging. Thirty-nine consecutive patients who had undergone coronary arteriography underwent 99Tcm-MIBI (740 Mbq) SPET after dipyridamole (0.84 mg kg-1) and after adenosine (0.84 mg kg-1), both combined with low-level exercise (30 W load), and under resting conditions. Our results demonstrate that adenosine and dipyridamole combined with exercise have comparable haemodynamic effects, with a low incidence of side-effects. The time of recovery from the stress protocol was not significantly different: adenosine, 5.7 +/- 3.9 min; dipyridamole, 6.6 +/- 4.9 min. However, aminophylline was significantly (P < 0.05) more often administered to reverse side-effects using the dipyridamole protocol (36% of patients) compared with the adenosine protocol (8% of patients). The results of 99Tcm-MIBI SPET imaging were highly concordant and demonstrated a high diagnostic accuracy for identifying coronary artery disease (CAD). The sensitivity was 90% (95% confidence intervals 79-100%) with adenosine SPET and 93% (95% confidence intervals 84-100%) with dipyridamole SPET for identifying patients with CAD (i.e. luminal stenosis > 50%); their specificities were both 100% (95% confidence intervals 66-100%). The sensitivity of identifying angiographically diseased vessels was 81% (95% confidence intervals 70-92%) using adenosine SPET and 85% (95% confidence intervals 75-95%) using dipyridamole; the specificity for both stress modalities was 94% (95% confidence intervals 89-100%). The combination of exercise with adenosine and high-dose dipyridamole appears to be a feasible and safe method to alleviate some of the undesirable A1-receptor-mediated side-effects of adenosine. The choice of the pharmacological stress will depend on local expertise and availability.

Adenosine↗
PubMed1996

Prevalence of esophageal disorders in patients with chest pain newly referred to the cardiologist.

STUDY OBJECTIVE: The prevalence of esophageal disorders (dysmotility and/or gastroesophageal reflux) in patients with chest pain newly referred to a cardiologic clinic is unknown. The aims of our study were to investigate the prevalence of esophageal abnormalities in these patients and to assess the value of medical history in predicting the origin of the patient's chest pain. DESIGN: We evaluated 28 consecutive patients who were newly referred to the cardiologist because of angina-like chest pain. Patients with evidence of severe myocardial ischemia were excluded. Cardiologic evaluation included medical history, physical examination, ECG, and exercise testing; further cardiologic workup was carried out only when considered necessary. Gastroenterologic evaluation consisted of medical history, esophageal manometry, endoscopy, and 24-h ambulatory monitoring of esophageal pH and pressure. MEASUREMENTS AND RESULTS: In five patients a diagnosis of ischemic coronary artery disease was made. In only two of these five patients, the cardiologic history strongly suggested a cardiac origin of the pain. Twelve patients had a pathologic 24-h pH profile, four of whom also had reflux esophagitis. Ten patients had symptomatic reflux. In only three of these ten patients, the history was judged to be indicative of an esophageal origin of the chest pain. No motility disorders were found. CONCLUSIONS: Thirty-six percent of the patients with chest pain newly referred to a cardiologic out-patient clinic have symptomatic gastroesophageal reflux. Neither cardiologic nor gastroenterologic history data have a high predictive value with respect to the origin of the chest pain.

Adult↗
PubMed1994

Quantitative analysis of planar technetium-99m Sestamibi myocardial perfusion images. Clinical application of a modified method for the subtracton of tissue crosstalk.

Application of the Thallium-201 quantitative analysis method to Tc-99m Sestamibi planar myocardial perfusion images results in oversubtraction of tissue crosstalk, defined as 'activity within the myocardial image, which originated outside the heart'. A modified algorithm, specific for Tc-99m Sestamibi, was applied in 60 patients and the results of quantitative analysis to estimate the risk of coronary artery disease were compared with coronary angiographic findings and with visual analysis. New crosstalk planes were generated based on the results in 20 male healthy volunteers. The results in our study group indicate a higher diagnostic accuracy when circumferential profiles are generated on the basis of maximal counts compared to mean counts. Quantitative analysis was able to predict the presence or absence of CAD as accurately as visual analysis. Odds ratios were 1.07 and 1.32 respectively (P < 0.001) for both quantitative maximal uptake and visual uptake analysis. Sensitivity of visual analysis alone was 89%, increasing to 96% with combined visual/quantitative analysis. Specificity of visual analysis decreased from 79% to 64% with combined analysis. Although only minor differences are seen, the maximal count uptake profiles were found to have additional diagnostic value compared to visual analysis alone.

Adult↗
PubMed1994

99Tcm-sestamibi SPECT with combined dipyridamole and exercise stress in coronary artery disease.

In order to evaluate the clinical value of 99Tcm-methoxyisobutylisonitrile (sestamibi) single photon emission computed tomography (SPECT) after dipyridamole infusion in combination with low level bicycle exercise for the assessment of the presence, localization and extent of coronary artery disease (CAD), myocardial perfusion imaging was performed in 76 patients. Low level bicycle exercise was used to supplement the standard dipyridamole infusion protocol because of the lower incidence of non-cardiac side effects. The results were compared to arteriographic findings obtained within 3 months of the SPECT studies. The overall sensitivity of detection of coronary artery disease (i.e. a luminal stenosis > 50%) was 81%, specificity 80%, positive predictive value 96%, negative predictive value 40% and accuracy 82%. The diagnostic values for the detection of significant stenoses in the three major coronary arteries were: left anterior descending artery sensitivity 72%, specificity 87% and accuracy 76%; right coronary artery sensitivity 75%, specificity 90% and accuracy 80%; left circumflex coronary artery sensitivity 57%, specificity 85% and accuracy 71%. Scintigraphic evidence of multivessel disease was found in 31 (65%) patients with two- or three-vessel involvement assessed by arteriography. False negative test results were mainly found in patients with relatively mild CAD (one-vessel disease, branch and distal disease). 99Tcm-sestamibi SPECT after dipyridamole infusion in combination with low level bicycle exercise is shown to be a valuable diagnostic tool for the evaluation of CAD.

Adult↗
PubMed1994

Head-to-head comparison between technetium-99m-sestamibi and thallium-201 tomographic imaging for the detection of coronary artery disease using combined dipyridamole-exercise stress.

AIM: The purpose of this study was a head-to-head comparison of tomographic imaging (SPECT) with technetium-99m (Tc-99m)-sestamibi and thallium-201 (Tl-201) using dipyridamole-low-level bicycle exercise stress for the assessment of coronary artery disease. METHODS: We studied 38 consecutive patients referred for the evaluation of chest pain who had undergone coronary angiography. The patients were randomly allocated to Tc-99m-sestamibi SPECT followed by Tl-201 SPECT or vice versa. The accuracy of both tracers in detecting significant coronary artery disease (> 50% luminal stenosis) was 87% (95% confidence interval 72-96%). Only two patients were classified differently by the two methods. RESULTS: On a segmental basis, good agreement was found between Tc-99m-sestamibi and Tl-201 for both the localization and the nature of perfusion defects (reversible or persistent) identified (Cohen's kappa = 0.67). CONCLUSION: No clinically relevant differences in diagnostic accuracy were demonstrated between Tc-99m-sestamibi and Tl-201 SPECT using combined dipyridamole-exercise stress for the evaluation of coronary artery disease.

Aged↗
PubMed1994

Adrenal insufficiency secondary to postoperative bilateral adrenal haemorrhage.

Two case reports are presented of adrenal insufficiency due to bilateral adrenal haemorrhage following surgery. This unusual complication with its non-specific manifestations may result in unexpected clinical deterioration of the postoperative patient. Corticosteroid replacement and repletion of sodium and water deficits should be given promptly when adrenal haemorrhage is suspected.

Adrenal Cortex Hormones↗
PubMed1992

[ACTH-producing small-cell lung carcinoma].

Small-cell lung cancer may be accompanied by hypercortisolism due to secretion of adrenal stimulating peptides. This occurs almost exclusively in case of extensive disease. The neuroendocrine cell, from which these tumours may originate, plays an important part in the production of these peptides. Four patients are described with small-cell lung cancer and clinical presentation of hypercortisolism, particularly manifesting itself with hypokalaemia.

Adrenocortical Hyperfunction↗
PubMed1991

99Tcm-SESTAMIBI for planar myocardial perfusion imaging; not as ideal as the physical properties.

99Tcm-methoxyisobutyl isonitrile (Tc-SESTAMIBI) has recently been introduced as a new myocardial perfusion agent which exhibits ideal physical properties for imaging with the gamma camera. To assess the diagnostic accuracy of planar Tc-SESTAMIBI, myocardial perfusion imaging was performed in 60 consecutive patients at rest and during exercise. The results were compared with coronary angiographic findings, obtained within 3 months of the exercise test. Planar 201Tl images were also performed on the same day and to the same level of stress as the Tc-SESTAMIBI exercise. Exact segmental agreement between Tc-SESTAMIBI and 201Tl was 77%. Nineteen per cent of all 900 segments demonstrated ischaemia with Tc-SESTAMIBI and 20% with 201Tl. The overall sensitivity for detecting haemodynamically significant coronary artery disease with Tc-SESTAMIBI was 86% and specificity was 78%; with 201Tl the values were 89 and 78%, respectively (differences not significant). Vessel-specific comparative detection rates revealed no statistical significant differences between both radiopharmaceuticals. Intra-observer variability for Tc-SESTAMIBI images was 12% and for 201Tl it was 14%. Inter-observer variability for Tc-SESTAMIBI was 14% and for 201Tl 17%. Although the physical characteristics of Tc-SESTAMIBI allow crisp and clear high-count density imaging, no significant differences are found when planar images are compared with 201Tl and are well within observer variabilities.

Adult↗
PubMed1991

Discordance of visual and quantitative analysis regarding false negative and false positive test results in thallium-201 myocardial perfusion scintigraphy.

Visual assessment and quantitative analysis of exercise thallium-201 myocardial perfusion scintigraphy was performed in 203 consecutive patients who underwent coronary arteriographic studies to identify the factors associated with false negative and false positive studies. Also the discordance between visual and quantitative analysis was evaluated. One hundred sixty-two (80%) of these 203 patients had significant coronary artery disease (CAD), i.e. a luminal stenosis greater than or equal to 50%. Fifty-two (32%) of these 162 patients with documented CAD showed negative thallium results either by visual or quantitative analysis. When interpreted visually 36/162 (22%) of patients were judged as negative, and when analyzed quantitatively 41/162 (25%) of patients were judged as negative (ns). Of the total group of 52 patients with false negative visual and/or quantitative analysis test results, 27 (17%) showed discordance between these two methods. Of the 41 patients without significant CAD, 12 (29%) showed positive thallium findings. Visual interpretation was positive in 9/41 (22%) of patients without significant CAD, and quantitative analysis in 5/41 (12%) (ns). Of the total group of 12 patients with positive visual and/or quantitative analysis test results, 10 (24%) showed discordance between these two methods. Therefore, in the total group, 37 patients (18%) showed discordance between visual and quantitative analysis. It is concluded that 1) the sensitivity and the specificity of visual interpretation and quantitative analysis of thallium-201 exercise scintigraphy for detecting CAD is similar, and 2) that there is frequent discordance of visual interpretation and quantitative analysis in thallium-201 exercise scintigraphy.

Coronary Disease↗
PubMed1990

Is quantitative analysis superior to visual analysis of planar thallium 201 myocardial exercise scintigraphy in the evaluation of coronary artery disease? Analysis of a prospective clinical study.

Quantitative analysis of myocardial exercise scintigraphy has been previously reported to be superior to visual image interpretation for detection of the presence and extent of coronary artery disease. Computer analysis of perfusion defects and washout rate of thallium 201 was performed on scintigrams from a group of 131 consecutive patients (prospective group), using criteria defined from a previous group of 72 patients (initial group), and compared with visual interpretation of scintigrams for detection and evaluation of coronary artery disease. The sensitivity of the quantitative technique with regard to overall detection of coronary artery disease was not significantly different from the visual method (69% and 74%, respectively), whereas the specificity was higher (86% and 68%). Quantitative analysis did not increase the sensitivity of thallium imaging over the visual method in the left anterior descending artery (46% vs 65%) and the right coronary artery (51% vs 72%) but did increase sensitivity in the left circumflex artery (75% vs 47%). Whereas in the initial group quantitative analysis resulted in a better identification of multivessel disease (sensitivity 81% vs 57%), in the prospective group sensitivity decreased (54% vs 67%) without significant loss of specificity. The initial group had a 40% incidence of three-vessel disease and the prospective group, 22% (P less than 0.05). One-vessel disease was higher in the prospective group (32% vs 11%, P less than 0.05). Thus, assessing the quantitative technique in a larger prospective patient population, there was no improvement of detection of the presence and extent of coronary artery disease when compared with visual interpretation.

Coronary Disease↗
PubMed1990

Improvement of diagnosis in the non-invasive assessment of coronary artery disease: enhanced evaluation of quantitative exercise 201thallium imaging by multivariate analysis.

STUDY OBJECTIVE: The aim was to evaluate discriminant analysis, performed in patients without prior myocardial infarction, in enhancing the diagnostic value of quantitative exercise 201thallium scintigraphy. DESIGN: All clinical, electrocardiographic, and scintigraphic variables were first subjected to a univariate analysis. Afterwards a discriminant analysis was done. PATIENTS: 135 patients (104 male) were studied. Age was 24-70 years, mean 55 years. MEASUREMENTS AND MAIN RESULTS: Two discriminant analyses were done. In the first analysis, the ability to detect the presence of coronary artery disease was tested. Significant variables were: (1) history of angina, (2) sex, (3) quantitative analysis of 201thallium scintigraphy, (4) age, (5) ischaemic ST response, (6) angina during the test, and (7) the pressure-rate product. The sensitivity, specificity, and accuracy of classification using the discriminant function were 91%, 87%, and 90%, respectively. The sensitivity was higher than when using only visual interpretation (sensitivity 70%; p less than 0.0002) or quantitative interpretation (sensitivity = 66%; p less than 0.0001) of thallium scans, without significant loss of specificity (p less than 0.5488; p less than 0.6875). In the second analysis, a discriminant function was calculated to detect multivessel disease. Five input variables were selected: (1) number of vessels with stenosis predicted by quantitative analysis, (2) number of vessels with stenosis predicted by visual analysis, (3) ischaemic ST response, (4) sex, (5) angina during the test. Multivariate analysis showed an increase in sensitivity when compared with visual interpretation (78% v 55%; p less than 0.0043) and quantitative analysis (66%; p less than 0.0156). Using the classification, the discriminant function was more accurate than visual analysis (81% v 69%) or quantitative analysis (77%). CONCLUSIONS: The results show that multivariate analysis of non-invasive test results in quantitative thallium exercise testing allows convenient use for clinical purposes with improved results.

Adult↗
PubMed1990

Comparative value of visual and quantitative analysis of thallium-201 imaging after exercise in patients with an abnormal baseline repolarization on the electrocardiogram at rest.

In this study the role of visual assessment and quantitative analysis of thallium-201 myocardial stress perfusion scintigraphy (MPS) was evaluated in patients with a normal electrocardiogram (ECG) (group I) and in patients with an abnormal baseline repolarization on the ECG (group II). One-hundred-and-thirty-five patients were studied. Group I consisted of 93 patients, 65 of whom had coronary artery disease (CAD), i.e. a luminal stenosis of greater than or equal to 50%; group II consisted of 42 patients, 32 of whom had CAD. In group II the exercise ECG was considered uninterpretable and thus only visual and quantitative analysis of MPS was investigated. Sensitivity and specificity of exercise electrocardiography, visual assessment and quantitative analysis of MPS were not significantly different in group I: sensitivities of the three methods were 66, 62 and 55% respectively, and specificities 86, 79 and 96% respectively. In group II there were no significant differences in the sensitivities and specificities of visual assessment or quantitative analysis of MPS: sensitivities of the two methods being both 88% and specificities both 80%. Visual assessment of redistribution (P less than 0.05) and quantitative analysis of washout (P less than 0.005) was significantly superior in group II than in group I; probably because of a higher incidence of three-vessel disease in the second group.(ABSTRACT TRUNCATED AT 250 WORDS)

Algorithms↗