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Biomedical subjects

Igor Klem

Publications and source records attributed to Igor Klem.

9 recordsLinked to original sources
PubMed2007

Rapid detection of myocardial infarction by subsecond, free-breathing delayed contrast-enhancement cardiovascular magnetic resonance.

BACKGROUND: An ultrafast, delayed contrast-enhancement cardiovascular magnetic resonance technique that can acquire subsecond, "snapshot" images during free breathing (subsecond) is becoming widely available. This technique provides myocardial infarction (MI) imaging with complete left ventricular coverage in < 30 seconds. However, the accuracy of this technique is unknown. METHODS AND RESULTS: We prospectively compared subsecond imaging with routine breath-hold delayed contrast-enhancement cardiovascular magnetic resonance (standard) in consecutive patients. Two cohorts with unambiguous standards of truth were prespecified: (1) patients with documented prior MI (n=135) and (2) patients without MI and with low likelihood of coronary disease (lowest Framingham risk category; n=103). Scans were scored masked to identity and clinical information. Sensitivity, specificity, and accuracy of subsecond imaging for MI diagnosis were 87%, 96%, and 91%, respectively. Compared with the standard technique (98%, 100%, 99%), the subsecond technique had modestly reduced sensitivity (P=0.0001), but specificity was excellent. Missed infarcts were generally small or subendocardial (87%). Overall, regional transmural extent of infarction scores were highly concordant (2083/2294; 91%); however, 51 of 337 regions (15%) considered predominantly infarcted (> 50% transmural extent of infarction) by the standard technique were considered viable (< or = 25% transmural extent of infarction) by the subsecond technique. Quantitative analysis demonstrated moderately reduced contrast-to-noise ratios for subsecond imaging between infarct and remote myocardium (12.0+/-7.2 versus 20.1+/-6.6; P<0.0001) and infarct and left ventricular cavity (-2.5+/-2.7 versus 3.6+/-3.7; P<0.0001). CONCLUSIONS: MI can be rapidly detected by subsecond delayed contrast-enhancement cardiovascular magnetic resonance during free breathing with high accuracy. This technique could be considered the preferred approach in patients who are more acutely ill or unable to hold their breath. However, compared with standard imaging, sensitivity is mildly reduced, and the transmural extent of infarction may be underestimated.

Adult↗
PubMed2006

Improved detection of coronary artery disease by stress perfusion cardiovascular magnetic resonance with the use of delayed enhancement infarction imaging.

OBJECTIVES: We tested a pre-defined visual interpretation algorithm that combines cardiovascular magnetic resonance (CMR) data from perfusion and infarction imaging for the diagnosis of coronary artery disease (CAD). BACKGROUND: Cardiovascular magnetic resonance can assess both myocardial perfusion and infarction with independent techniques in a single session. METHODS: We prospectively enrolled 100 consecutive patients with suspected CAD scheduled for X-ray coronary angiography. Patients had comprehensive clinical evaluation, including Rose angina questionnaire, 12-lead electrocardiography, C-reactive protein, and calculation of Framingham risk. Cardiovascular magnetic resonance included cine, adenosine-stress and rest perfusion-CMR, and delayed enhancement-CMR (DE-CMR) for infarction imaging. Matched stress-rest perfusion defects in the absence of infarction by DE-CMR were considered artifactual. All patients underwent X-ray angiography within 24 h of CMR. RESULTS: Ninety-two patients had complete CMR examinations. Significant CAD (> or =70% stenosis) was found in 37 patients (40%). The combination of perfusion and DE-CMR had a sensitivity, specificity, and accuracy of 89%, 87%, and 88%, respectively, for CAD diagnosis, compared with 84%, 58%, and 68%, respectively, for perfusion-CMR alone. The combination had higher specificity and accuracy (p < 0.0001), owing to incorporating the exceptionally high specificity (98%) of DE-CMR. Receiver operating characteristic curve analysis demonstrated the combination provided better performance than cine, perfusion, or DE-CMR alone. The accuracy was high in single-vessel and multivessel disease and independent of CAD location. Multivariable analysis including standard clinical parameters demonstrated the combination was the strongest independent CAD predictor. CONCLUSIONS: A combined perfusion and infarction CMR examination with a visual interpretation algorithm can accurately diagnose CAD in the clinical setting. The combination is superior to perfusion-CMR alone.

Aged↗
PubMed2006

Where's the flap?

We present a case of aortic intramural hematoma (IMH) in an elderly woman who presented with sudden onset of mid-scapular pain. The patient underwent a series of multimodality imaging studies before the diagnosis of IMH was evident by cardiovascular magnetic resonance, which is rapidly becoming the gold standard in the evaluation of acute aortic disease due to its high spatial resolution and ability to characterize tissue composition. Early diagnosis and prompt treatment is critical in improving the outcome of patients with IMH.

Aged↗
PubMed2005

Noninvasive assessment of blood flow based on magnetic resonance global coherent free precession.

BACKGROUND: Magnetic resonance global coherent free precession (GCFP) is a new technique that produces cine projection angiograms directly analogous to those of x-ray angiography noninvasively and without a contrast agent. In this study, we compared GCFP blood flow with "gold standards" to determine the accuracy of noninvasive GCFP blood flow measurements. METHODS AND RESULTS: The relationship between GCFP blood flow and true blood flow defined by invasive ultrasonic flow probe and by phase contrast velocity encoded MRI (VENC) was studied in anesthetized dogs (n=6). Blood flow was controlled by use of a hydraulic occluder around the left iliac artery. GCFP images were acquired by selectively exciting the abdominal aorta and visualizing temporal blood flow into the iliac arteries. GCFP flow was similar to ultrasonic blood flow at baseline (131.3+/-44.8 versus 114.8+/-34.2 mL/min), during occlusion (10.8+/-5.1 versus 6.5+/-7.2 mL/min), during reactive hyperemia (191.4+/-100.7 versus 260.3+/-138.7 mL/min), during the new resting state (135.5+/-52.4 versus 117.8+/-24.1 mL/min), and during partial occlusion (61.4+/-36.4 versus 49.3+/-13.1 mL/min, P=NS for all). Results comparing GCFP flow with VENC were similar. Statistical analysis revealed that GCFP flow was related to mean blood flow assessed by the flow probe (P<0.0001) and by VENC (P<0.0001). In the control right iliac artery, conversely, GCFP measurements were unaffected throughout all left iliac interventions (P=NS). CONCLUSIONS: GCFP blood flow is linearly related to true blood flow for a straight, cylindrical blood vessel without branches. Although more complex geometries imply a qualitative rather than a quantitative relationship, the data nevertheless suggest that GCFP may serve as the basis for a new form of noninvasive stress testing.

Animals↗
PubMed2005

The case of the disappearing myxoma.

We present a case demonstrating the utility of cardiovascular magnetic resonance (CMR) in the diagnosis of a cardiac mass. A 70-year-old female who presented with chest pressure and left sided jaw pain was found to have a cardiac mass on transthoracic and transesophageal echocardiography that was diagnosed as an atrial myxoma. A cardiac magnetic resonance test determined the mass to be more consistent with a thrombus than a myxoma through a stepwise approach using multiple pulse sequences. Thus, unwarranted and potentially risky thoracic surgery was avoided by the incorporation of a systematic evaluation by cardiac MRI.

Aged↗
PubMed2004

Mortality and rate of stroke or embolism in atrial fibrillation during long-term follow-up in the embolism in left atrial thrombi (ELAT) study.

BACKGROUND: Patients with atrial fibrillation (AF) have a higher mortality and risk of stroke/embolism than patients with sinus rhythm. HYPOTHESIS: The aim of the study was to assess the association of clinical and echocardiographic characteristics with mortality and stroke/embolism and the use of antithrombotic medication in the year 2000 in patients who participated 1990-1995 in the Embolism in Left Atrial Thrombi (ELAT) study. METHODS: The study included 409 outpatients with nonrheumatic AF (62 +/- 12 years, 36% women, 39% intermittent AF). Patients with thrombi received anticoagulation, patients without thrombi aspirin until follow-up in 1995; thereafter, anticoagulation according to clinical risk factors was recommended. Primary events were death and secondary events were stroke/embolism. All patients were contacted during the year 2000. RESULTS: Mean follow-up was 102 months. Mortality was 4%/year; the cause of death was cardiac (n = 84), fatal stroke (n = 26), malignancy (n = 23), sepsis (n = 5), and unknown (n = 24). Multivariate analysis identified age (p < 0.0001), heart failure (p = 0.0013), and reduced left ventricular systolic function (p = 0.0353) as predictors of mortality. Stroke/embolism occurred in 83 patients, with a rate of 3%/year. Multivariate analysis identified age (p = 0.0006) and previous stroke (p = 0.0454) as predictors of stroke/embolism. In the year 2000, 51 (21%) of the 247 surviving patients received no antithrombotic medication, 88 received (36%) oral anticoagulants, 102 (41%) acetylsalicylic acid, and 6 (2%) low-molecular heparin. CONCLUSIONS: Therapy for heart failure and oral anticoagulation in AF should be seriously considered, especially in elderly patients and in those with previous stroke.

Age Factors↗
PubMed2004

Video-assisted thoracoscopic transplantation of myoblasts into the heart.

PURPOSE: Currently, cells are transplanted into injured myocardium either through thoracotomy for open surgical delivery or through catheterization for endoventricular or intracoronary delivery; both methods have limitations. Open surgical delivery limits the potential patient population, whereas catheter-based delivery limits the ability to visualize the injection site and confirm delivery of the cells to the appropriate region. In this study, we examine the feasibility of cell transplantation into myocardium using a minimally invasive thoracoscopic approach. DESCRIPTION: Seven swine underwent thoracoscopic cell transplantation. Using a prototype injection device, approximately 10 million myoblasts were injected into the anterior, lateral, posterior, and apical regions of myocardium. Animals were recovered up to 7 days, and after euthanasia, hearts were explanted for histology. EVALUATION: All seven swine had successful delivery of myoblasts into the defined injection sites, as confirmed by analysis of an operative video, magnetic resonance imaging of iron-oxide-labeled cells, and histologic examination. CONCLUSIONS: Thoracoscopic cellular cardiomyoplasty is feasible and allows the surgeon the benefits of direct visualization of the cell injection while minimizing morbidity associated with open cell delivery.

Animals↗
PubMedDate not supplied

Diabetic atrial fibrillation patients: mortality and risk for stroke or embolism during a 10-year follow-up.

BACKGROUND: To compare in atrial fibrillation patients with and without diabetes, (1) baseline characteristics, (2) additional risk factors for stroke or peripheric or visceral embolism (hypertension, previous stroke, age >75 years), (3) mortality, (4) stroke or embolism, and (5) oral anticoagulation in the year 2000. METHODS: Included were 409 outpatients with nonrheumatic atrial fibrillation (62 +/- 12 years, 36% female). All underwent transthoracic and transesophageal echocardiography. Patients with thrombi received oral anticoagulation; patients without thrombi received aspirin until the follow-up in 1995; afterwards, oral anticoagulation according to risk factors for stroke or embolism was recommended. Patients were contacted during the year 2000. RESULTS: Type 2 diabetes was diagnosed in 73 patients (18%). Sixteen (22%) diabetic and 169 (50%) nondiabetic patients had no other risk factors for stroke or embolism (p < 0.0001). Diabetic patients were older, had more frequent heart failure, hypertension, myocardial infarction, left ventricular dysfunction, valvular abnormalities, left atrial or appendage thrombi, larger left atria, and left atrial appendages than nondiabetic patients. Mean follow-up was 115 months. Diabetic patients had a higher mortality than nondiabetic patients (7%/year versus 4%/year, p < 0.0001). The rate of stroke or embolism of diabetic (3%/year) and nondiabetic patients (2%/year) was similar. The rate of oral anticoagulation was higher in diabetic than in nondiabetic patients (p = 0.0066). CONCLUSIONS: Diabetic patients with atrial fibrillation frequently have additional risk factors for stroke or embolism, and thus should be treated with oral anticoagulation. Whether in the rare cases of atrial fibrillation, in whom diabetes is the only clinical risk factor, oral anticoagulation is indicated cannot be answered by the present study.

Aged↗