Tomas Kovarnik

Coronary versus carotid blood flow and coronary perfusion pressure in a pig model of prolonged cardiac arrest treated by different modes of venoarterial ECMO and intraaortic balloon counterpulsation

IntroductionExtracorporeal membrane oxygenation (ECMO) is increasingly used in cardiac arrest (CA). Adequacy of carotid and coronary blood flows (CaBF, CoBF) and coronary perfusion pressure (CoPP) in ECMO treated CA is not well established. This study compares femoro-femoral (FF) to femoro-subclavian (FS) ECMO and intraaortic balloon counterpulsation (IABP) contribution based on CaBF, CoBF, CoPP, myocardial and brain oxygenation in experimental CA managed by ECMO.MethodsIn 11 female pigs (50.3 ± 3.4 kg), CA was randomly treated by FF versus FS ECMO ± IABP. Animals under general anesthesia had undergone 15 minutes of ventricular fibrillation (VF) with ECMO flow of 5 to 10 mL/kg/min simulating low-flow CA followed by continued VF with ECMO flow of 100 mL/kg/min. CaBF and CoBF were measured by a Doppler flow wire, cerebral and peripheral oxygenation by near infrared spectroscopy. CoPP, myocardial oxygen metabolism and resuscitability were determined.ResultsCaBF reached values > 80% of baseline in all regimens. CoBF > 80% was reached only by the FF ECMO, 90.0% (66.1, 98.6). Addition of IABP to FF ECMO decreased CoBF to 60.7% (55.1, 86.2) of baseline, P = 0.004. FS ECMO produced 70.0% (49.1, 113.2) of baseline CoBF, significantly lower than FF, P = 0.039. Addition of IABP to FS did not change the CoBF; however, it provided significantly higher flow, 76.7% (71.9, 111.2) of baseline, compared to FF + IABP, P = 0.026. Both brain and peripheral regional oxygen saturations decreased after induction of CA to 23% (15.0, 32.3) and 34% (23.5, 34.0), respectively, and normalized after ECMO institution. For brain saturations, all regimens reached values exceeding 80% of baseline, none of the comparisons between respective treatment approaches differed significantly. After a decline to 15 mmHg (9.5, 20.8) during CA, CoPP gradually rose with time to 68 mmHg (43.3, 84.0), P = 0 .003, with best recovery on FF ECMO. Resuscitability of the animals was high, both 5 and 60 minutes return of spontaneous circulation occured in eight animals (73%).ConclusionsIn a pig model of CA, both FF and FS ECMO assure adequate brain perfusion and oxygenation. FF ECMO offers better CoBF than FS ECMO. Addition of IABP to FF ECMO worsens CoBF. FF ECMO, more than FS ECMO, increases CoPP over time.

Standardized evaluation methodology and reference database for evaluating IVUS image segmentation

This paper describes an evaluation framework that allows a standardized and quantitative comparison of IVUS lumen and media segmentation algorithms. This framework has been introduced at the MICCAI 2011 Computing and Visualization for (Intra)Vascular Imaging (CVII) workshop, comparing the results of eight teams that participated. We describe the available data-base comprising of multi-center, multi-vendor and multi-frequency IVUS datasets, their acquisition, the creation of the reference standard and the evaluation measures. The approaches address segmentation of the lumen, the media, or both borders; semi- or fully-automatic operation; and 2-D vs. 3-D methodology. Three performance measures for quantitative analysis have been proposed. The results of the evaluation indicate that segmentation of the vessel lumen and media is possible with an accuracy that is comparable to manual annotation when semi-automatic methods are used, as well as encouraging results can be obtained also in case of fully-automatic segmentation. The analysis performed in this paper also highlights the challenges in IVUS segmentation that remains to be solved.

Intravascular ultrasound assessment of coronary artery involvement in Fabry disease

SummaryAimWe used intravascular ultrasound (IVUS) to characterize coronary artery involvement in patients with Fabry disease (FD).MethodsNine FD patients (5 women) were matched to 10 control patients (5 women) chosen from our IVUS database. Standard volumetric IVUS analyses were performed along with assessment of plaque echodensity.ResultsPlaques in FD patients were diffuse and hypoechogenic compared with more focal and more echogenic lesions in control patients. Echogenicity of plaques was significantly lower in FD patients (median 30.7  ±  12.9 vs 55.9  ±  15.7, p  =  0.0052, mean 37.2  ±  15.6 vs 66.2  ±  13.3, p  =  0.0014). Diffusiveness was assessed as differences between mean and median plaque burden versus the plaque burden in each of the analysed cross-sections. These differences were lower in FD vs controls (5.8  ±  4.8 vs 8.7  ±  6.6, p  <  0.001 for mean, and 5.8  ±  4.9 vs 8.8  ±  7.3, p  <  0.001 for median) indicating a more diffuse involvement. The occurrence of lipid cores was significantly higher in FD patients than in controls (2.4  ±  1.5 vs 1.0  ±  0.94, p  =  0.02).ConclusionIVUS showed diffuse hypoechogenic plaques in patients with FD. The explanation may be higher lipid content in plaques and accumulation of glycosphingolipid in smooth-muscle and endothelial cells.

Simultaneous Registration of Location and Orientation in Intravascular Ultrasound Pullbacks Pairs Via 3D Graph-Based Optimization

A novel method is reported for simultaneous registration of location (axial direction) and orientation (circumferential direction) of two intravascular ultrasound (IVUS) pullbacks of the same vessel taken at different times. Monitoring plaque progression or regression (e.g., during lipid treatment) is of high clinical relevance. Our method uses a 3D graph optimization approach, in which the cost function jointly reflects similarity of plaque morphology and plaque/perivascular image appearance. Graph arcs incorporate prior information about temporal correspondence of the two IVUS sequences and limited angular twisting between consecutive IVUS images. Additionally, our approach automatically identifies starting and ending frame pairs in the two IVUS pullbacks. Validation of our method was performed in 29 pairs of IVUS baseline/follow-up pullback sequences consisting of 8 622 IVUS image frames in total. In comparison to manual registration by three experts, the average location and orientation registration errors ranged from 0.72 mm to 0.79 mm and from 7.3 ° to 9.3 °, respectively, all close to the inter-observer variability with no difference being statistically significant (p = NS). Rotation angles determined by our automated approach and expert observers showed high correlation ( r2 of 0.97 to 0.98) and agreed closely (mutual bias between the automated method and expert observers ranged from -1.57° to 0.15 °). Compared with state-of-the-art approaches, the new method offers lower errors in both location and orientation registration. Our method offers highly automated and accurate IVUS pullback registration and can be employed in IVUS-based studies of coronary disease progression, enabling more focal studies of coronary plaque development and transition of vulnerability.

Long-term prognostic impact of hyponatremia in the ST-elevation myocardial infarction

Abstract Aims. The aim of the study was to analyse in-hospital outcomes and long-term prognostic implications of reduced sodium serum level (S-Na) in the early phase of ST elevation myocardial infarction (STEMI) treated, primarily, with direct percutaneous coronary intervention (dPCI). Methods and results. The study included 218 consecutive patients (144 males, the mean age 64 ± 13 years) with no history of heart failure admitted with acute STEMI. Out of them, 193 (88.5%) patients were treated with dPCI. The mean follow-up period was 39 ± 21 months. Hyponatremia was defined as S-Na value < 135 mmol/L. A total of 72 (33%) patients reached hyponatremia level; 51(23.4%) of them at admission and 21 (9.6%) later during hospitalization. The hyponatremic patients more frequently presented with reduced left ventricular systolic function, Killip class III or IV and were at increased risk of developing cardiogenic shock compared to patients with normonatremia. Compared to the rest of the population, patients who developed hyponatremia later during hospitalization had higher incidence of acute renal failure; (12 patients/6.1% vs. 5 patients/25.5%, p < 0.05). The difference in long-term survival between the hyponatremia and normonatremia groups was significant (p = 0.01, log-rank test). The multiple analysis of variance identified decrease of S-Na levels at admission independently associated with total mortality (p = 0.05). Conclusion. Patients who developed hyponatremia in the early phase of STEMI were at higher risk of worse in-hospital clinical outcome. During the long-term follow-up, higher mortality rates were recorded in hyponatremic patients.

Interventional left atrial appendage closure vs novel anticoagulation agents in patients with atrial fibrillation indicated for long-term anticoagulation (PRAGUE-17 study)

Background Atrial fibrillation (AF), with a prevalence of 1% to 2%, is the most common cardiac arrhythmia. Without antithrombotic treatment, the annual risk of a cardioembolic event is 5% to 6%. The source of a cardioembolic event is a thrombus, which is usually formed in the left atrial appendage (LAA). Prevention of cardioembolic events involves treatment with anticoagulant drugs: either vitamin K antagonists or, recently, novel oral anticoagulants (NOAC). The other (nonpharmacologic) option for the prevention of a cardioembolic event involves interventional occlusion of the LAA. Objective To determine whether percutaneous LAA occlusion is noninferior to treatment with NOAC in AF patients indicated for long‐term systemic anticoagulation. Study design The trial will be a prospective, multicenter, randomized noninferiority trial comparing 2 treatment strategies in moderate to high‐risk AF patients (ie, patients with history of significant bleeding, or history of cardiovascular event(s), or a with CHA2DS2VASc ≥3 and HAS‐BLED score ≥2). Patients will be randomized into a percutaneous LAA occlusion (group A) or a NOAC treatment (group B) in a 1:1 ratio; the randomization was done using Web‐based randomization software. A total of 396 study participants (198 patients in each group) will be enrolled in the study. The primary end point will be the occurrence of any of the following events within 24 months after randomization: stroke or transient ischemic attack (any type), systemic cardioembolic event, clinically significant bleeding, cardiovascular death, or a significant periprocedural or device‐related complications. Conclusion The PRAGUE‐17 trial will determine if LAA occlusion is noninferior to treatment with NOAC in moderate‐ to high‐risk AF patients.

The late stent malapposition develops also after paclitaxel balloon predilatation before bare-metal stent implantation: case description.

The patient is a 57-year-old non-diabetic woman admitted for stable angina caused by tight stenosis of a diagonal branch. This lesion was predilated with a paclitaxel-eluting balloon (2.5 × 20 mm, Sequent, B Braun Mesungen AG, Germany) at 8 atm for 3 min after which a 2.25 × 28 mm bare-metal stent (Trimaxx; Abbott Vascular Redwood City, CA, USA) was implanted for a small …

A rationale for early extracorporeal membrane oxygenation in patients with postinfarction ventricular septal rupture complicated by cardiogenic shock: ECMO in patients with ventricular septal rupture

Ventricular septal rupture (VSR) became a rare mechanical complication of myocardial infarction in the era of percutaneous coronary interventions but is associated with extreme mortality in patients who present with cardiogenic shock (CS). Promising outcomes have been reported with the use of circulatory support allowing haemodynamic stabilization, followed by delayed repair. Therefore, we analysed our experience with an early use of Veno‐Arterial Extracorporeal Membrane Oxygenation (V‐A ECMO) for postinfarction VSR.

Prospective Prediction of Thin-Cap Fibroatheromas from Baseline Virtual Histology Intravascular Ultrasound Data

Thin-cap fibroatheroma (TCFA) is particularly prone to rupture, which may result in myocardial infarction and death. Virtual histology intravascular ultrasound (VH-IVUS) provides quantitative information about plaque composition and enables TCFA identification. However, prospective prediction of future development of TCFA has not been previously possible. The aim of our study was to determine whether subsequent development of TCFA can be predicted from baseline VH-IVUS data. Corresponding VH-IVUS images of baseline and follow-up examinations were identified by a highly automated approach to register IVUS pullback pairs from 24 patients (2,331 image pairs). Next, 20 location-specific VH-based and IVUS-based features including plaque phenotype and morphology, and 15 systemic patient-specific features were extracted and ranked using a support vector machine recursive feature elimination (SVM RFE) technique. SVM was applied to assess the prediction power of different feature sets, by adding the first n-ranked features to the classification procedure (leave-one-patient-out cross validation) iteratively until all features were considered. The experimental results showed that the prospective prediction of TCFA achieves a sensitivity of 72.6% and a specificity of 73.3%, when an optimal set of the five best selected features is used. The results indicate the feasibility of prospective prediction of TCFA formation based on baseline VH-IVUS data.

Joint registration of location and orientation of intravascular ultrasound pullbacks using a 3D graph based method

A novel method for simultaneous registration of location and orientation of baseline and follow-up intravascular ultrasound (IVUS) pullbacks is reported. The main idea is to represent the registration problem as a 3D graph optimization problem (finding a minimum-cost path) solvable by dynamic programming. Thus, global optimality of the resulting location and orientation registration is guaranteed according to the employed cost function and node connections. The cost function integrates information related to vessel/plaque morphology, plaque shape and plaque/perivascular image data. The node connections incorporate the prior information about angular twisting between consecutively co-registered IVUS image pairs. Pilot validation of our method is currently available for four pairs of IVUS pullback sequences consisting of 323 IVUS image frames from four patients. Results showed the average location and orientation registration errors were 0.26 mm and 5.2°, respectively. Compared with our previous results, the new method offers significant alignment improvement (p < 0.001).