Ischemic heart disease: value of MR techniques

Background. The cardiovascular applications of magnetic resonance (MR) techniques in coronary artery disease have increased considerably in recent years. Technical advantages of MR imaging are the excellent spatial resolution, the characterization of myocardial tissue, and the potential for three-dimensional imaging. These characteristics allow the accurate assessment of left ventricular mass and volume, the differentiation of infarcted from normal tissue, and the determination of systolic wall thickening and regional wall motion abnormalities. Methods. In addition to the conventionally used spin-echo and cine-echo techniques, newer techniques such as myocardial tagging, ultrafast MR imaging and MR coronary angiography have been developed. These newer techniques allow a more accurate assessment of ventricular function (tagging), myocardial perfusion (ultrafast imaging), and evaluation of stenosis severity (MR coronary angiography). Particularly early detection and flow assessment of stenosed coronary arteries and bypasses by MR angiography would constitute a major breakthrough in cardiovascular MR imaging. Apart from the MR imaging techniques, cardiac metabolism may be well assessed using MR spectroscopy. This provides unique information on the metabolic behaviour of the myocardium under conditions stress-induced ischemia. However, the definite niche of cardiac MR spectroscopy has still to be settled. Conclusion. Currently, MR techniques allow the evaluation of anatomy and function (accepted use), perfusion and viability (development phase), and coronary angiography (experimental phase). A particular strength of MR imaging is that one single MR test may encompass cardiac anatomy, perfusion, function, metabolism and coronary angiography. The replacement of multiple diagnostic tests with one MR test may have major effects on cardiovascular healthcare economics and would outweigh the cost inherent to the MR angiography procedure.     

Validation of coronary artery saphenous vein bypass graft diameter measurements using quantitative angiography

The accepted value for reproducibility (true change) is two standard deviations (SD) of the differences between repeat measurements. It has been well established for coronary artery measurements using several different quantitative coronary angiography (QCA) systems, but it has not been well documented for saphenous vein grafts (SVG). The purpose of this study was to assess, using the Cardiovascular Measurement System (CMS), the measurement reproducibility of 24 vein grafts from 24 patients who had symptom-directed control angiography. Three equal graft segments were studied separately. Focal narrowings expressed in percent stenosis varied from 5 to 80% (mean 20.8±15.9%). The average minimum lumen diameter (MLD) was 3.07±0.81 mm and the average interpolated reference diameter (Ref.D) was 3.87±0.58 mm. We assessed the reproducibility of measurements obtained from two separate imagings of the graft in the same view but at least 20 minutes apart, near the beginning and at the end of the angiographic procedure (simulating baseline and end-trial examinations). The SD for differences in measurements (variability) was 0.183 mm for the MLD, 0.193 mm for the Ref.D, 0.184 mm for the mean diameter (Mean D) and 3.72% for the percent diameter stenosis (PDS). A reasonable true change cut-off for SVG measurements in our laboratory is ≥ 0.4 mm for the minimum and mean lumen diameters, and ≥ 10% for the PDS, when QCA is obtained with the QCA-CMS analytical software package.     

Higher carotid-radial pulse wave velocity is associated with non-melancholic depressive symptoms in men – findings from Helsinki Birth Cohort Study

BackgroundDepression and cardiovascular disease (CVD) are major causes of global disease burden that are interrelated through mostly unknown mechanisms. We studied the relationship of melancholic and non-melancholic depressive symptoms with arterial stiffness, an important underlying mechanism of CVD.MethodsThe Helsinki Birth Cohort Study recruited 683 previously extensively phenotyped subjects for this sub-study. Cross-sectional data along with responses regarding depressive symptoms were obtained for each participant. For evaluation of depressive symptoms, the Beck Depression Inventory (BDI)and subscales were used to measure melancholic and non-melancholic depressive symptoms. Arterial stiffness was assessed as pulse wave velocity (PWV) that was measured between the carotid and radial artery, and carotid and femoral artery.ResultsOf the participants, 532 scored <10 on the BDI and were classified as not having depressive symptoms. Of the 151 participants that scored ≥10 on the BDI, 122 were classified as having non-melancholic depressive symptoms and 29 as having melancholic depressive symptoms. Men had higher carotid-radial PWV (crPWV) values than women (p < .001). A positive relationship between BDI scores and crPWV (p < .001) was found in men. We also found higher crPWV in men with non-melancholic depressive symptoms compared to all others. No such differences were found in women.DiscussionArterial stiffness has a relationship with depressive symptoms and subtypes of depressive symptoms, at least in men. There is a significant relationship between higher PWV and non-melancholic depressive symptoms in men. Due to the intricate nature of the disease causality or directionality is impossible to infer solely based on this study. Further studies into the subtypes of depressive symptoms may be of benefit to understanding depression.

KEY MESSAGES

• It is known that arterial stiffness contributes to cardiovascular disease, and is associated with depression.
• Higher Beck Depression Inventory scores are associated with higher carotid-radial pulse wave velocity in men.
• Non-melancholic depressive symptoms are associated with higher carotid-radial pulse wave velocity in men.

     

Leisure time physical activity is associated with poor glycemic control in type 1 diabetic women: the FinnDiane study

OBJECTIVE: We studied the association between leisure time physical activity (LTPA) and glycemic control, insulin dose, and estimated glucose disposal rate (eGDR) in type 1 diabetes. RESEARCH DESIGN AND METHODS: This is a cross-sectional study of 1,030 type 1 diabetic patients participating in the Finnish Diabetic Nephropathy Study, a nationwide multicenter study. LTPA was assessed by a validated 12-month questionnaire and expressed in metabolic equivalent (MET) units. Patients were grouped as sedentary (LTPA <10 MET h/week, n = 247), moderately active (LTPA 10-40 MET h/week, n = 568), and active (LTPA >40 MET h/week, n = 215). Outcome measures were HbA(1c), insulin dose, and eGDR (estimate of insulin sensitivity based on waist-to-hip ratio, hypertension, and HbA(1c)). RESULTS: LTPA correlated with HbA(1c) in women (r = -0.12, P = 0.007) but not in men (r = -0.03, P = 0.592). Sedentary women had higher HbA(1c) than moderately active and active women: 8.8 +/- 1.4% vs. 8.3 +/- 1.4% vs. 8.3 +/- 1.4% (P = 0.004), whereas HbA(1c) in men was 8.4 +/- 1.3% vs. 8.2 +/- 1.4% vs. 8.2 +/- 1.3% (P = 0.774), respectively. In men, insulin doses were 0.74 +/- 0.21 vs. 0.71 +/- 0.20 vs. 0.68 +/- 0.23 IU . kg(-1) . 24 h(-1) (P = 0.003). In both sexes, sedentary patients had lower eGDRs than active patients [median (interquartile range) 5.5 (4.0-8.2) vs. 6.8 (4.7-8.8) vs. 6.7 (4.6-8.6) mg . kg(-1) . min(-1); P < 0.01 for sedentary vs. others]. Age, obesity, smoking, insulin dose, social class, diabetic nephropathy, or cardiovascular disease did not explain the results. CONCLUSIONS: Low levels of LTPA were associated with poor glycemic control in type 1 diabetic women. Men seem to use less insulin when physically active. Increased LTPA levels were associated with increased estimated insulin sensitivity. Longitudinal studies are needed to further clarify the effects of LTPA on type 1 diabetes.     

Bedside estimation of absolute renal blood flow and glomerular filtration rate in the intensive care unit

Objective To evaluate various treatment strategies in critically ill patients with ischaemic acute renal failure, there is a need for reliable bedside measurements of total renal blood flow (RBF), glomerular filtration rate (GFR) and renal oxygen consumption without the need for urine collection.Design The continuous renal vein thermodilution method and the infusion clearance techniques were validated against the gold standard technique, the urinary clearance of paraaminohippurate (PAH) and chromium ethylenediaminetetraacetic acid, respectively.Setting University hospital cardiothoracic ICU.Patients Seventeen uncomplicated mechanically ventilated post-cardiac surgical patients.Interventions None.Measurements and results Renal blood flow, GFR and the renal filtration fraction (FF) were measured for two consecutive 30-min periods by urinary clearance and compared with simultaneous measurements made by the thermodilution and infusion clearance techniques. Urinary clearance for PAH was corrected for by renal extraction of PAH. The within-group error, repeatability coefficient and the coefficient of variation were highest for the thermodilution technique and lowest for the infusion clearance technique with regard to RBF, GFR and FF. The infusion clearance technique had a higher agreement with the urinary clearance method than the thermodilution method. For estimations of RBF and GFR, the between-group errors were 33% and 43% comparing infusion clearance with urinary clearance and 65% and 67% comparing thermodilution with urinary clearance.Conclusions The infusion clearance method had the highest reproducibility and the highest agreement with the urinary clearance reference method. The renal vein thermodilution technique is less reliable in the ICU setting due to poor repeatability and poor agreement with the reference method.     

Efficacy of cidofovir in a murine model of disseminated progressive vaccinia

An animal model that mimics progressive disseminated vaccinia was elaborated. To this end nude (athymic) mice were inoculated intracutaneously with vaccinia virus in the lumbosacral area. Viral replication (DNA) in the skin was detected as early as day 2 postinfection (p.i.). Mice developed typical vaccinia lesions at the site of inoculation by day 4 to 6 p.i. By about 2 weeks p.i., the infection had spread all over the body, a situation reminiscent of disseminated vaccinia in humans. The infection resulted in viremia and spread of the virus to visceral organs, as well as to the brain. Topical treatment with cidofovir, initiated at the day of infection or at day 1 p.i., completely protected against virus-induced cutaneous lesions and against associated mortality. When treatment was initiated at a later time (day 2 to 5 p.i.), a partial but marked protective effect was noted, which can be explained by the fact that by that time, the virus had spread from the skin to the visceral organs. Next, infected animals were left untreated until the time ( approximately 2 weeks p.i.) at which disseminated vaccinia had developed. When systemic treatment with cidofovir was initiated at that time, it caused lesions to heal and regress. In most of these animals, lesions had completely (or almost completely) disappeared by day 10 to 15 after the start of therapy. The observation that cidofovir is able to cause healing of disseminated vaccinia lesions in animals should have implications for the therapy of complications of vaccination against smallpox.     

Ultrasound nucleolysis: an in vitro study

Thermal intradiscal therapy for chronic low back pain, using a catheter inserted into the intervertebral disc, is becoming more popular in the treatment of low back pain. The aim of this study was to investigate the possibility of heating the nucleus pulposus of the intervertebral disc with high-intensity focused ultrasound (US) or HIFU. Two specific situations were considered, invasive transducers that would be in contact with the annulus fibrosus of the disc, and noninvasive transducers that could be used externally. Theoretical simulations were performed to find the optimal parameters of US transducers and then experimental studies were done using transducers made to these specifications. These experiments confirmed that it was possible to heat the discs with HIFU. Two orthogonal transducers resulted in a superior temperature distribution than using just one transducer. It is, therefore, feasible to consider thermal treatment of the nucleus pulposus of the disc using noninvasive US.