Apr 24, 2017

Recent publications



Several center members have published results from their studies in international scientific journals this year.

Below you can read a short overview of the following articles;
- Left ventricular dysfunction is related to the presence and extent of a septal flash in patients with right ventricular pacing
- High-Sensitivity Troponin T vs I in Acute Coronary Syndrome: Prediction of Significant Coronary Lesions and Long-term Prognosis
- Temperature monitoring by channel data delays: Feasibility based on estimated delays magnitude for cardiac ablation
- Focused cardiac ultrasound by unselected residents-the challenges
- Real-time catheter localization and visualization using three-dimensional echocardiography

Category: General
Posted by: Piritta


Sarvari SI, Sitges M, Sanz M, Tolosana Viu JM, Edvardsen T, Stokke TM, Mont L, Bijnens B
Left ventricular dysfunction is related to the presence and extent of a septal flash in patients with right ventricular pacing.
Europace. 2017 Feb 1;19(2):289-296. doi: 10.1093/europace/euw020. No abstract available.
PMID: 28175277

Septal flash (SF), a marker of left ventricular (LV) dyssynchrony in the presence of a left bundle branch block (LBBB), has been shown to predict improved ventricular function and outcome when corrected with cardiac resynchronization therapy. We hypothesized that a SF is present in patients receiving right ventricular (RV) pacing and its presence and extent could predict the development of LV dysfunction and remodeling.

For patients with sinus-node dysfunction and advanced atrioventricular (AV) conduction disorders, cardiac pacing is the only effective treatment. In cardiac pacing, the right ventricular (RV) apex is typically the place where the endocardial pacing lead is positioned due to the ease of site accessibility and lead stability. Generally, RV apical pacing is effective and well tolerated. However, increasing amount of data has shown that conventional RV apical pacing may have unfavourable effects on cardiac structure and left ventricular (LV) function, and may lead to heart failure and increased mortality. Upgrade to cardiac resynchronization therapy (CRT) may to some extent reverse the unfavourable effects of RV apical pacing. Furthermore, it has even been proposed that selected patients with indication for conventional pacemaker treatment should receive CRT as primary treatment to prevent the unfavourable effects of RV pacing.2–5 However, CRT implantation is expensive and it is difficult to predict which patients will develop dyssynchrony and heart failure due to RV pacing and which patients will respond to CRT. It has been shown in earlier studies that a septal flash (SF), defined as early fast inward/outward motion of the interventricular septum during isovolumic contraction and within the QRS complex, is a hallmark of the mechanical consequences of a left bundle branch block (LBBB) and serves as a correctable mechanism that could predict response to CRT as well as outcome.  However, it has not been investigated whether a SF is present in patients with RV pacing, whether it can be used as a marker of LV mechanical dyssynchrony, and whether it is a mechanistic event that relates to LV dysfunction.


A SF was present in a majority of patients receiving conventional RV pacing and its magnitude was related to LV dysfunction and adverse remodeling. Given the similarities observed in LBBB and pacemaker-induced dyssynchrony, SF magnitude might be a predictor for the development of LV dysfunction and adverse remodeling in patients receiving conventional RV pacing.


Kvisvik B, Mørkrid L, Røsjø H, Cvancarova M, Rowe AD, Eek C, Bendz B, Edvardsen T, Gravning J
High-Sensitivity Troponin T vs I in Acute Coronary Syndrome: Prediction of Significant Coronary Lesions and Long-term Prognosis.
Clin Chem. 2017 Feb;63(2):552-562. doi: 10.1373/clinchem.2016.261107
PMID: 27974383


High-sensitivity cardiac troponin (hs-cTn) T and I assays are established as crucial tools for the diagnosis of acute myocardial infarction (AMI), as they have been found superior to old troponin assays. However, eventual differences between the assays in prediction of significant coronary lesions and long-term prognosis in patients with acute coronary syndrome (ACS) have not been fully unraveled.

The definition of acute myocardial infarction (AMI) continues to evolve as more sensitive biomarkers are developed. Measurement of cardiac troponins (cTns) has become important in the diagnosis of AMI, and rapid identification of AMI is essential for the initiation of effective treatment and management.

High-sensitivity cardiac troponin (hs-cTn) assays have recently been shown to be superior to conventional cTn assays for the early diagnosis of AMI. Current guidelines recommend the use of a cTn cutoff-concentration at the 99th percentile of healthy controls, together with a rise and/or fall pattern. The measurement of hs-cTn should be made at admission and repeated 3–6 h later. Owing to increased but stable concentrations of cTn in some chronic diseases, dynamic changes become a critical part of the AMI diagnosis. However, it is essential to separate dynamic changes resulting from AMI from dynamic changes associated with analytical imprecision or normal chronobiological variation.


The hs-cTnT and hs-cTnI assays displayed a similar ability to predict significant coronary lesions among NSTE-ACS patients. NT-proBNP is superior to both hs-cTn assays as a prognostic marker in this patient group. Our data suggest that the observed differences between hs-cTnT and hs-cTnI assays have biological rather than analytical explanations. However, further studies are needed to further explore the relevance of differences between the 2 high-sensitivity troponin assays in cardiovascular disease.


Pasternak M, Samset E, D'hooge J, Haugen GU
Temperature monitoring by channel data delays: Feasibility based on estimated delays magnitude for cardiac ablation.
Ultrasonics. 2017 Jan 16;77:32-37. doi: 10.1016/j.ultras.2017.01.011. [Epub ahead of print]
PMID: 28167318


Ultrasound thermometry is based on measuring tissue temperature by its impact on ultrasound wave propagation. This study focuses on the use of transducer array channel data (not beamformed) and examines how a layer of increased velocity (heat induced) affects the travel-times of the ultrasound backscatter signal. Based on geometric considerations, a new equation was derived for the change in time delay as a function of temperature change. The resulting expression provides insight into the key factors that link change in temperature to change in travel time. It shows that velocity enters in combination with heating geometry: complementary information is needed to compute velocity from the changes in travel time. Using the bio-heat equation as a second source of information in the derived expressions, the feasibility of monitoring the temperature increase during cardiac ablation therapy using channel data was investigated. For an intra-cardiac (ICE) probe, using this “time delay error approach” would not be feasible, while for a trans-esophageal array transducer (TEE) transducer it might be feasible.


Application of the proposed equations to a model of cardiac radio-frequency ablation monitored with two cardiac probes indicated that the difference in arrival time along the aperture is more likely to be detectable using a transeophageal (TEE) probe than along the aperture of the intra-cardiac (ICE) probe. These results eliminate the ICE probe as a candidate for such monitoring of thermal ablation. Investigations should be performed more thoroughly for studies considering the TEE probe in such protocols.


Ruddox V, Norum IB, Stokke TM, Edvardsen T, Otterstad JE
Focused cardiac ultrasound by unselected residents-the challenges.
BMC Med Imaging. 2017 Mar 4;17(1):22. doi: 10.1186/s12880-017-0191-y
PMID: 28259149


Focus Cardiac Ultrasound (FoCUS) performed by internal medicine residents on call with 2 h of training can provide a means for ruling out cardiac disease, but with poor sensitivity. The purpose of the present study was to evaluate diagnostic usefulness as well as diagnostic accuracy of FoCUS following 4 h of training.


All residents on call were given a 4-h training course with an additional one-hour training course after 6 months. They were asked to provide a pre- and post-FoCUS diagnosis, with the final diagnosis at discharge as reference.


During a 7 month period 113 FoCUS examinations were reported; after 53 were excluded this left 60 for evaluation with a standard echocardiogram performed on average 11.5 h after FoCUS. Examinations were performed on the basis of chest pain and dyspnoea/edema. The best sensitivity was found in terms of the detection of reduced left ventricular (LV) ejection fraction (EF) (92%), LV dilatation (85%) and pericardial effusion (100%). High values were noted for negative predictive values, although false positives were seen. A kappa > 0.6 was observed for reduced LVEF, right ventricular area fraction and dilatation of LV and left atrium. In 48% of patients pre- and post-FoCUS diagnoses were identical and concordant with the final diagnosis. Importantly, in 30% examinations FoCUS correctly changed the pre-FoCUS diagnosis.


A FoCUS protocol with a 4-h training program gained clinical usefulness in one third of examinations. False positive findings represented the major challenge.


Kozlowski P, Bandaru RS,  D'hooge J, Samset E
Real-time catheter localization and visualization using three-dimensional echocardiography
Proc. SPIE 10135, Medical Imaging 2017: Image-Guided Procedures, Robotic Interventions, and Modeling, 1013518 (March 3, 2017); doi:10.1117/12.2253835

Real-time three-dimensional transesophageal echocardiography (RT3D-TEE) is increasingly used during minimally invasive cardiac surgeries (MICS). In many cath labs, RT3D-TEE is already one of the requisite tools for image guidance during MICS. However, the visualization of the catheter is not always satisfactory making 3D- TEE challenging to use as the only modality for guidance. We propose a novel technique for better visualization of the catheter along with the cardiac anatomy using TEE alone - exploiting both beamforming and post processing methods. We extended our earlier method called Delay and Standard Deviation (DASD) beamforming to 3D in order to enhance specular reflections. The beam-formed image was further post-processed by the Frangi filter to segment the catheter. Multi-variate visualization techniques enabled us to render both the standard tissue and the DASD beam-formed image on a clinical ultrasound scanner simultaneously. A frame rate of 15 FPS was achieved.

Heart SFI