Incremental role of CT coronary angiography in the assessment of left ventricular diastolic function

OBJECTIVE

To determine whether Computed Tomography (CT) coronary angiography (CTCA) has clinical value for the assessment of left ventricular (LV) diastolic dysfunction (DD) beyond traditional information on coronary artery anatomy.

METHOD

In this retrospective study, a consecutive group of 72 patients (mean age 59±13 years)-who met the eligibility criteria of sinus rhythm, no significant valvular abnormalities, and who had transthoracic echocardiogram (TTE)-were analysed. The CTCA was prospectively triggered during diastole. Outcomes of interest were CTCA derived LV and left atrial (LA) volumes, diastolic expansion (DE) index: LV volume÷LA volume and DE fraction (DEF): [(LV volume-LA volume)÷LV volume]×100. TTE-LA volume was measured as maximum, minimum and pre-A. Studied patients were divided according to the current classification of LVDD as a reference standard. A small subgroup of nine patients underwent further invasive cardiac catheterisation.

RESULTS

CTCA-LV and LA volumes were larger compared with TTE, 37%±20% and 11%±21%, respectively. CTCA-LA volume correlated well with all TTE-LA volumes (maximum: R2=0.58; pre-A wave: R2=0.39; minimum: R2=0.26; p<0.0001) with the smallest differences in maximum LA volume (9±32 mL; mean±2 SD). The DE and DEF correlated with both LA function and LVDD. DE >1.65 and DE <1.40 have good specificity (85% and 88%, respectively), and positive predictive value to differentiate LVDD. DE and DEF were dependent on the patients' age but independent of other variables.

CONCLUSIONS

CTCA derived diastasis volume indices can provide additional quantifiable information on LVDD.

Ion channel drug discovery and research: the automated Nano-Patch-Clamp technology

Unlike the genomics revolution, which was largely enabled by a single technological advance (high throughput sequencing), rapid advancement in proteomics will require a broader effort to increase the throughput of a number of key tools for functional analysis of different types of proteins. In the case of ion channels -a class of (membrane) proteins of great physiological importance and potential as drug targets- the lack of adequate assay technologies is felt particularly strongly. The available, indirect, high throughput screening methods for ion channels clearly generate insufficient information. The best technology to study ion channel function and screen for compound interaction is the patch clamp technique, but patch clamping suffers from low throughput, which is not acceptable for drug screening. A first step towards a solution is presented here. The nano patch clamp technology, which is based on a planar, microstructured glass chip, enables automatic whole cell patch clamp measurements. The Port-a-Patch is an automated electrophysiology workstation, which uses planar patch clamp chips. This approach enables high quality and high content ion channel and compound evaluation on a one-cell-at-a-time basis. The presented automation of the patch process and its scalability to an array format are the prerequisites for any higher throughput electrophysiology instruments.

High Quality Ion Channel Analysis on a Chip with the NPC© Technology

In evaluating ion channel function, electrophysiology, e.g., patch clamping, provides the highest information content. For the analysis of ion channel-modulating compounds, one variant of the patch-clamp technique, the whole-cell configuration, is particularly useful. We present here patch-clamp recordings in the whole-cell configuration and single channel recordings performed with planar patch-clamp chips, which are microstructured from borosilicate glass substrate. The chips are used in the Port-a-Patch, an ion channel research/screening instrument that enables automated patch-clamp experiments on a single cell. A software runs the experiment by executing user-determined protocols for cell positioning, as well as for electrical stimulation and current readout. In various electrophysiological experiments, the high quality of recordings and the versatility of the perfusion of the recorded cells are demonstrated. Quantitative pharmacological experiments are performed on sodium channels expressed in HEK cells using solution volumes in the low microliter range. The exceptionally low volume consumption in the experiments make the system attractive for work on rare or expensive compounds. Due to the low volumes necessary, a rapid solution exchange is facilitated, which is shown on RBL cells. The patch-clamp chip enables a rapid and precise perfusion, allowing sophisticated investigations on ion channel function with the Port-a-Patch.