Cardiomyopathies: focus on cardiovascular magnetic resonance

Cardiomyopathies (CMPs) are a group of often inherited diseases characterised by abnormalities and associated dysfunction of heart muscle. In the past decade, cardiovascular magnetic resonance (CMR) has emerged as a powerful tool in their assessment, providing data that are complementary to other aspects of clinical evaluation. Key advantages of CMR are three-dimensional visualisation of the heart and its relationship to thoracic structures; gold-standard quantification of cardiac volumes and function, which can safely be repeated over time (no ionising radiation is involved); and tissue characterisation to detect focal scar and fatty infiltration. This paper reviews the role of CMR in the clinical assessment of patients with CMPs.

Comparative clinical- and cost-effectiveness of candesartan and losartan in the management of hypertension and heart failure: a systematic review, meta- and cost-utility analysis

The UK National Health Service (NHS) currently spends in excess of £250 million per annum on angiotensin II receptor blockers (ARBs) for the treatment of hypertension and heart failure; with candesartan currently dominating the market. With the recent introduction of generic losartan, we set out to directly compare the branded market leader to its now cheaper alternative. The primary objectives were to compare the blood pressure (BP) lowering efficacy and cardiovascular outcomes of candesartan and losartan in the treatment of essential hypertension and chronic heart failure, respectively. The secondary objective was to model their comparative incremental cost-effectiveness in a UK NHS setting. The Cochrane Central Register of Controlled Trials (Cochrane Library 2009, issue 2), which contains the Hypertension and Heart Group's specialist register, Medline (1950-February 2010), and Embase (1980-February 2010) were included in the search strategy. Selection criteria were randomised studies of candesartan versus losartan in adults (> 18 years). The main outcome measures were as follows: Hypertension: mean change from baseline in trough (24 h postdose) systolic and diastolic BP. Heart failure: composite of cardiovascular death and hospital admission for management of heart failure. Two reviewers applied inclusion criteria, assessed trial quality, and extracted data. Eight (three of which met inclusion criteria) and zero trials compared candesartan directly with losartan in the treatment of hypertension and heart failure, respectively. A between-treatment difference of -1.96 mmHg [95% confidence interval (CI) -2.40 to -1.51] for trough diastolic BP and -3.00 mmHg (95% CI -3.79 to -2.22) for trough systolic BP in favour of candesartan was observed. Based on this differential, a 10-year Markov model estimates the cost per quality-adjusted life-year gained to exceed £40,000 for using candesartan in place of generic losartan. Candesartan reduces BP to a slightly greater extent when compared with losartan, however, such difference is unlikely to be cost-effective based on current acquisition costs, perceived NHS affordability thresholds and use of combination regimens. We could find no robust evidence supporting the superiority of candesartan over losartan in the treatment of heart failure. We therefore recommend using generic losartan as the ARB of choice which could save the UK NHS approximately £200 million per annum in drug costs.

Expressional diversity of wheat nsLTP genes: evidence of subfunctionalization via cis-regulatory divergence

Previously, the wheat non-specific lipid transfer proteins (TaLTP), members of a small multigene family, were reported to evidence a complex pattern of expression regulation. In order to assess further the expression diversity of the TaLTP genes, we have attempted to evaluate their expression profiles in responses to abiotic stresses, using semi-quantitative RT-PCR. The expression profiles generated herein revealed that the TaLTP genes in group A evidenced highly similar responses against abiotic stresses, whereas differential expression patterns among genes in each group were also observed. A total of seven promoters were fused to a GUS reporter gene and the recombinants were introduced into Arabidopsis, while three promoters evidenced non-detectible GUS activity. The promoters of TaLTP1, TaLTP7, and TaLTP10 included in group A drove strong expressions during plant development with overlapping patterns, in large part, but also exhibited distinct expression pattern, thereby suggesting subfunctionalization processing over evolutionary time. However, only trace expression in cotyledons, young emerged leaves, and epidermal cell layers of flower ovaries was driven by the promoter of TaLTP3 of group B. These results indicate that their distinct physiological functions appear to be accomplished by a subfunctionalization process involving degenerative mutations in regulatory regions.

A gene family encoding RING finger proteins in rice: their expansion, expression diversity, and co-expressed genes

The proteins harboring RING finger motif(s) have been shown to mediate protein-protein interactions that are relevant to a variety of cellular processes. In an effort to elucidate the evolutionary dynamics of the rice RING finger protein family, we have attempted to determine their genomic locations, expression diversity, and co-expressed genes via in silico analysis and semi-quantitative RT-PCR. A total of 425 retrieved genes appear to be distributed over all 12 of the chromosomes of rice with different distributions, and are reflective of the evolutionary dynamics of the rice genome. A genome-wide dataset harboring 155 gene expression omnibus sample plates evidenced some degree of differential evolutionary fates between members of RING-H2 and RING-HC types. Additionally, responses to abiotic stresses, such as salinity and drought, demonstrated that some degree of expression diversity existed between members of the RING finger protein genes. Interestingly, we determined that one RING-H2 finger protein gene (Os04g51400) manifested striking differences in expression patterns in response to abiotic stresses between leaf and culm-node tissues, further revealing responses highly similar to the majority of randomly selected co-expressed genes. The gene network of genes co-expressed with Os04g51400 may suggest some role in the salt response of the gene. These findings may shed further light on the evolutionary dynamics and molecular functional diversity of these proteins in complex cellular regulations.

The "OBS" chart: an evidence based approach to re-design of the patient observation chart in a district general hospital setting

OBJECTIVE

The primary role of the patient bedside observation chart is to make clinicians aware of the deteriorating patient. Despite this, its performance has not been scrutinised. Many versions exist with different styles of data entry but the optimal format remains elusive. This paper hypothesised that chart design measurably influences function and that redesign and standardisation would improve the detection of physiological decline by clinical staff.

DESIGN

Objective evaluation of existing charts (n = 5), evidence based redesign, and re-evaluation of new chart.

SETTING

250 bed district general hospital.

RESULTS

Design of existing observation charts had a significant effect on the ability of clinical staff to detect patient deterioration, with detection rates of parameters indicating physiological decline ranging from 0% to 100%. Graphical plots portrayed information better than written values for all parameters being measured except tachypnoea. No single existing chart was best for all variables. A new chart was designed, implemented with training in its use, and re-evaluated. The new chart also incorporated an early warning scoring system. There were significant improvements in the average detection rates of parameters poorly identified on existing charts: detection rates of tachypnoea and hypoxia increased by 41% (p<0.05) and 45% (p<0.05) respectively. There were also significant improvements in detection rates of tachycardia and fever by 29% (p<0.05) and 16% (p<0.05) respectively.

CONCLUSION

Evidence based redesign of the patient bedside observation chart coupled with specific training in its use significantly improves the detection of patient physiological deterioration.

Myocardial late gadolinium enhancement cardiovascular magnetic resonance in hypertrophic cardiomyopathy caused by mutations in troponin I

OBJECTIVE

To examine the influence of genotype on late gadolinium enhancement (LGE) and the potential of cardiovascular magnetic resonance (CMR) to detect preclinical hypertrophic cardiomyopathy.

DESIGN

Prospective, blinded cohort study of myocardial LGE in a genetically homogeneous population.

PATIENTS

30 patients with disease causing mutations in the recognised hypertrophic cardiomyopathy gene for cardiac troponin I (TNNI3): 15 with echocardiographically determined left ventricular hypertrophy (LVH+) and 15 without (LVH-).

MAIN OUTCOME MEASURES

CMR measures of regional left ventricular function, wall thickness, and mass, and the extent and distribution of LGE.

RESULTS

LGE was found in 12 (80%) LVH+ patients but with variable extent (mean 15%, range 3-48%). LGE was also found in two (13%) LVH- patients but the extent was limited (3.6%) and both patients were found to have an abnormal ECG and regional hypertrophy by cine CMR. The extent of LGE was positively associated with clinical markers of sudden death risk (21% with > or = 2 risk factors v 7% with < or = 1 risk factor, p = 0.02) and left ventricular mass (r = 0.56, p < 0.001) and was inversely associated with ejection fraction (r = -0.58, p < 0.001). Segmental analysis showed that as regional wall thickness increased, LGE was more prevalent (p < 0.0001) and more extensive (r = 0.98, p = 0.001).

CONCLUSION

In patients with disease causing mutations in TNNI3, focal fibrosis was not detected by LGE CMR before LVH and ECG abnormalities were present. Once LVH is present, LGE is common and the extent correlates with adverse clinical parameters. This suggests that focal fibrosis is closely linked to disease development.

Improved cine cardiovascular magnetic resonance using Clariscan (NC100150 injection)

We evaluated the use of Clariscan 0.75, 2, and 5 mg Fe/kg body weight in six patients to determine optimal dosing for short repetition time cine imaging. Breathhold cine images were acquired in the vertical and horizontal long axes and the short axis. Blood-pool signal-to-noise ratio increased significantly in all planes (p < 0.01) but was least marked in the short axis. Myocardial signal-to-noise ratio increased by a lesser amount (p < 0.05). Myocardial to blood-pool signal-difference-to-noise ratio improved significantly in the long axes (p < 0.05) and was greatest at 2 mg Fe/kg body weight, but changes in the short axis were minor. With the 5-mg Fe/kg body weight dose, the response was reduced or reversed due to T2* effects. Visual assessment improved in all planes (p < 0.05) and was optimal at 2 mg Fe/kg body weight. In conclusion, Clariscan improves short repetition time cardiac breathhold cine imaging, particularly in the long axis planes, with an optimal dose of 2 mg Fe/kg body weight.