Andreas Napp

Comparison of Two- and Three-Dimensional Transthoracic Echocardiography to Cardiac Magnetic Resonance Imaging for Assessment of Paravalvular Regurgitation After Transcatheter Aortic Valve Implantation

This study evaluated 2-dimensional (2D) transthoracic echocardiography (TTE) using Valve Academic Research Consortium-2 (VARC-2) criteria and 3-dimensional (3D) TTE for assessment of aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) in comparison with cardiac magnetic resonance (CMR) imaging. In 71 patients, 2D TTE, 3D TTE, and CMR imaging were performed to assess AR severity after TAVI. Using 2D TTE, AR severity was graded according to VARC-2 criteria and regurgitant volume (RVol) was determined. Three-dimensional color Doppler TTE allowed direct planimetry of the vena contracta area of the paravalvular regurgitation jet and calculation of the RVol as product with the velocity-time integral. RVol by CMR imaging was measured by phase-contrast velocity mapping in the ascending aorta. After TAVI, mean RVol determined by CMR imaging was 9.2 ± 9.6 ml/beat and mean regurgitant fraction was 13.3 ± 10.3%. AR was assessed as none or mild in 58 patients (82%) by CMR imaging. Correlation of 3D TTE and CMR imaging on RVol was better than correlation of 2D TTE and CMR imaging (r = 0.895 vs 0.558, p <0.001). There was good agreement between RVol by CMR imaging and by 3D TTE (mean bias = 2.4 ml/beat). Kappa on grading of AR severity was 0.357 between VARC-2 and CMR imaging versus 0.446 between 3D TTE and CMR imaging. Intraobserver variability for analysis of RVol of AR after TAVI was 73.5 ± 52.2% by 2D TTE, 16.7 ± 21.9% by 3D TTE, and 2.2 ± 2.0% by CMR imaging. In conclusion, 2D TTE considering VARC-2 criteria has limitations in the grading of AR severity after TAVI when CMR imaging is used for comparison. Three-dimensional TTE allows quantification of AR with greater accuracy than 2D TTE. Observer variability on RVol after TAVI is considerable using 2D TTE, significantly less using 3D TTE, and very low using CMR imaging.

Dependency of cardiac resynchronization therapy on myocardial viability at the LV lead position.

OBJECTIVES This study sought to analyze the effectiveness of cardiac resynchronization therapy (CRT) related to the viability in the segment of left ventricular (LV) lead position defined by myocardial deformation imaging. BACKGROUND Echocardiographic myocardial deformation analysis allows determination of LV lead position as well as extent of myocardial viability. METHODS Myocardial deformation imaging based on tracking of acoustic markers within 2-dimensional echo images (GE Ultrasound, GE Healthcare, Horton, Norway) was performed in 65 heart failure patients (54 ± 6 years of age, 41 men) before and 12 months after CRT implantation. In a 16-segment model, the LV lead position was defined based on the segmental strain curve with earliest peak strain, whereas the CRT system was programmed to pure LV pacing. Nonviability of a segment (transmural scar formation) was assumed if the peak systolic circumferential strain was >-11.1%. RESULTS In 47 patients, the LV lead was placed in a viable segment, and in 18 patients, it was placed in a nonviable segment. At 12-month follow-up there was greater decrease of LV end-diastolic volumes (58 ± 13 ml vs. 44 ± 12 ml, p = 0.0388) and greater increase of LV ejection fraction (11 ± 4% vs. 5 ± 4%, p = 0.0343) and peak oxygen consumption (2.5 ± 0.9 ml/kg/min vs. 1.7 ± 1.1 ml/kg/min, p = 0.0465) in the viable compared with the nonviable group. The change in LV ejection fraction and the reduction in LV end-diastolic volumes at follow-up correlated to an increasing peak systolic circumferential strain in the segment of the LV pacing lead (r = 0.61, p = 0.0274 and r = 0.64, p = 0.0412, respectively). Considering only patients with ischemic heart disease, differences between viable and nonviable LV lead position group were even greater. CONCLUSIONS Preserved viability in the segment of the CRT LV lead position results in greater LV reverse remodeling and functional benefit at 12-month follow-up. Deformation imaging allows analysis of viability in the LV lead segment.

Effects of the β3-Adrenergic Agonist BRL 37344 on Endothelial Nitric Oxide Synthase Phosphorylation and Force of Contraction in Human Failing Myocardium

BACKGROUND In nonfailing myocardium, beta(3)-adrenergic signaling causes a decrease in contractility via endothelial nitric oxide synthase (eNOS) activation and nitric oxide (NO) release. This study investigates the hypothesis that beta(3)-adrenergic signaling undergoes alterations in failing myocardium. METHODS We compared eNOS- and beta(3)-adrenoceptor expression using Western blot analysis in human nonfailing myocardium versus failing myocardium. With the use of immunohistochemistry, we investigated the distribution of the beta(3)-adrenoceptor protein and eNOS translocation and phosphorylation under basal conditions. beta(3)-adrenergic, eNOS activation, and inotropy were measured in failing myocardium using BRL37344 (BRL, a beta(3)-adrenoceptor agonist). RESULTS beta(3)-adrenoceptor expression was increased in failing myocardium. Under basal conditions, Akt- and eNOS(Ser1177) phosphorylation were reduced in failing myocardium. During stimulation with BRL in failing myocardium, a further dephosphorylation of eNOS(Ser1177) and Akt was observed, whereas eNOS(Ser114) phosphorylation was increased. These results suggest a deactivation of eNOS via beta(3)-adrenergic stimulation. Nevertheless, BRL decreased contractility in failing myocardium, but this effect was not observed in the presence of the NO blocker L-NMA. In failing myocardium, the beta(3)-adrenoceptor was predominantly expressed in endothelial cells. In the cardiomyocytes, the beta(3)-adrenoceptor was mainly located at the intercalated disks. CONCLUSION In failing cardiomyocytes, beta(3)-adrenergic stimulation seems to deactivate rather than activate eNOS. At the same time, beta(3)-adrenergic stimulation induced a NO-dependent negative inotropic effect. Because beta(3)-adrenoceptors are expressed mainly in the endothelium in failing myocardium, our observations suggest a paracrine-negative inotropic effect via NO liberation from the cardiac endothelial cells.

Electromagnetic Interference With Implantable Cardioverter-Defibrillators at Power Frequency An In Vivo Study

Background— The number of implantable cardioverter-defibrillators (ICDs) for the prevention of sudden cardiac death is continuing to increase. Given the technological complexity of ICDs, it is of critical importance to identify and control possible harmful electromagnetic interferences between various sources of electromagnetic fields and ICDs in daily life and occupational environments. Methods and Results— Interference thresholds of 110 ICD patients (1-, 2-, and 3-chamber ICDs) were evaluated in a specifically developed test site. Patients were exposed to single and combined electric and magnetic 50-Hz fields with strengths of up to 30 kV·m−1 and 2.55 mT. Tests were conducted considering worst-case conditions, including maximum sensitivity of the device or full inspiration. With devices being programmed to nominal sensitivity, ICDs remained unaffected in 91 patients (83%). Five of 110 devices (5%) showed transient loss of accurate right ventricular sensing, whereas 14 of 31 (45%) of the 2- and 3-chamber devices displayed impaired right atrial sensing. No interference was detected in 71 patients (65%) within the tested limits with programming to maximum sensitivity, whereas 20 of 110 subjects (18%) exhibited right ventricular disturbances and 19 of 31 (61%) subjects exhibited right atrial disturbances. Conclusions— Extremely low-frequency daily-life electromagnetic fields do not disturb sensing capabilities of ICDs. However, strong 50-Hz electromagnetic fields, present in certain occupational environments, may cause inappropriate sensing, potentially leading to false detection of atrial/ventricular arrhythmic events. When the right atrial/right ventricular interferences are compared, the atrial lead is more susceptible to electromagnetic fields. Clinical Trial Registration— URL: http://clinicaltrials.gov/ct2/show/NCT01626261. Unique identifier: NCT01626261.

Are patients with cardiac implants protected against electromagnetic interference in daily life and occupational environment

Utilization of cardiac implants such as pacemakers and implantable cardioverter defibrillators is now commonplace among heart disease patients. The ever-increasing technological complexity of these devices is matched by the near omnipresent exposure to electric, magnetic, and electromagnetic fields (EMFs), both in everyday life and the occupational environment. Given that electromagnetic interferences (EMIs) are associated with potential risk in device patients, physicians are increasingly confronted with managing device patients with intermittent EMI and chronic occupational exposure. The current review aims to provide a contemporary overview of cardiovascular implantable electronic devices, their function and susceptibility of non-medical EMFs and provide recommendations for physicians caring for cardiac device patients presenting with EMI.

Effect of lead position and orientation on electromagnetic interference in patients with bipolar cardiovascular implantable electronic devices

Aims Electromagnetic interferences (EMIs) with cardiovascular implantable electronic devices (CIEDs) are associated with potential risk for patients. Studies imply that CIED sensitivity setting and leads tip‐to‐ring spacing determine the susceptibility of CIEDs with bipolar leads to electric and magnetic fields (EMFs); however, little is known about additional decisive parameters affecting EMI of CIEDs. We therefore investigated the influence of different patient‐, device‐, and lead‐depending variables on EMIs in 160 patients. Methods and results We ran numerical simulations with human models to determine lead‐depending variables on the risk of EMI by calculating the voltage induced in bipolar leads from 50/60 Hz EMF. We then used the simulation results and analysed 26 different patient‐, device‐, and lead‐depending variables with respect to the EMI threshold of 160 CIED patients. Our analyses revealed that a horizontal orientation and a medial position of the bipolar leads distal end (lead‐tip) are most beneficial for CIED patients to reduce the risk of EMI. In addition, the effect of CIED sensitivity setting and leads tip‐to‐ring spacing was confirmed. Conclusion Our data suggest that in addition to the established influencing factors, a medial position of the lead‐tip for the right ventricular lead as achievable at the interventricular septum and a horizontal orientation of the lead‐tip can reduce the risk of EMI. In the right atrium, a horizontal orientation of the lead‐tip should generally be striven independent of the chosen position. Still important to consider remains a good intrinsic sensing amplitude during implant procedure.

Heartbeat Cycle Length Detection by a Ballistocardiographic Sensor in Atrial Fibrillation and Sinus Rhythm

Background. Heart rate monitoring is especially interesting in patients with atrial fibrillation (AF) and is routinely performed by ECG. A ballistocardiography (BCG) foil is an unobtrusive sensor for mechanical vibrations. We tested the correlation of heartbeat cycle length detection by a novel algorithm for a BCG foil to an ECG in AF and sinus rhythm (SR). Methods. In 22 patients we obtained BCG and synchronized ECG recordings before and after cardioversion and examined the correlation between heartbeat characteristics. Results. We analyzed a total of 4317 heartbeats during AF and 2445 during SR with a correlation between ECG and BCG during AF of r = 0.70 (95% CI 0.68–0.71, P < 0.0001) and r = 0.75 (95% CI 0.73–0.77, P < 0.0001) during SR. By adding a quality index, artifacts could be reduced and the correlation increased for AF to 0.76 (95% CI 0.74–0.77, P < 0.0001, n = 3468) and for SR to 0.85 (95% CI 0.83–0.86, P < 0.0001, n = 2176). Conclusion. Heartbeat cycle length measurement by our novel algorithm for BCG foil is feasible during SR and AF, offering new possibilities of unobtrusive heart rate monitoring. This trial is registered with IRB registration number EK205/11. This trial is registered with clinical trials registration number NCT01779674.

Feasibility of Bioelectrical Impedance Spectroscopy Measurement before and after Thoracentesis

Background. Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. Methods. 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for “Transthoracic,” “Foot to Foot,” “Foot to Hand,” and “Hand to Hand” vectors in low and high frequency domain before and after thoracentesis. Healthy subjects were measured at a single time point. Results. The mean volume of removed pleural effusion was 1169 ± 513 mL. The “Foot to Foot,” “Hand to Hand,” and “Foot to Hand” vector indicated a trend for increased bioelectrical impedance after thoracentesis. Values for the low frequency domain in the “Transthoracic” vector increased significantly (P < 0.001). A moderate correlation was observed between the amount of removed fluid and impedance change in the low frequency domain using the “Foot to Hand” vector (r = −0.7). Conclusion. Bioelectrical impedance changes in correlation with the thoracic fluid level. It was feasible to monitor significant fluid shifts and loss after thoracentesis in the “Transthoracic” vector by means of bioelectrical impedance spectroscopy. The trial is registered with Registration Numbers IRB EK206/11 and NCT01778270.

Unobtrusive Nocturnal Heartbeat Monitoring by a Ballistocardiographic Sensor in Patients with Sleep Disordered Breathing

Sleep disordered breathing (SDB) is known for fluctuating heart rates and an increased risk of developing arrhythmias. The current reference for heartbeat analysis is an electrocardiogram (ECG). As an unobtrusive alternative, we tested a sensor foil for mechanical vibrations to perform a ballistocardiography (BCG) and applied a novel algorithm for beat-to-beat cycle length detection. The aim of this study was to assess the correlation between beat-to-beat cycle length detection by the BCG algorithm and simultaneously recorded ECG. In 21 patients suspected for SDB undergoing polysomnography, we compared ECG to simultaneously recorded BCG data analysed by our algorithm. We analysed 362.040 heartbeats during a total of 93 hours of recording. The baseline beat-to-beat cycle length correlation between BCG and ECG was rs = 0.77 (n = 362040) with a mean absolute difference of 15 ± 162 ms (mean cycle length: ECG 923 ± 220 ms; BCG 908 ± 203 ms). After filtering artefacts and improving signal quality by our algorithm, the correlation increased to rs = 0.95 (n = 235367) with a mean absolute difference in cycle length of 4 ± 72 ms (ECG 920 ± 196 ms; BCG 916 ± 194 ms). We conclude that our algorithm, coupled with a BCG sensor foil provides good correlation of beat-to-beat cycle length detection with simultaneously recorded ECG.

Detection of Acute Changes in Left Ventricular Function by Myocardial Deformation Analysis after Excessive Alcohol Ingestion

Background: The effects of acute excessive alcohol ingestion on echocardiographic parameters of left ventricular (LV) function are unclear. Methods: One hundred ninety‐nine healthy subjects (44 ± 5 years, 71% male) were prospectively examined within 6 hours after excessive alcohol ingestion as well as after 4 weeks with strict alcohol abstinence. Echocardiography was performed at baseline and follow‐up for conventional parameters (left ventricular ejection fraction [LVEF], transmitral E and A Doppler flow velocities, E/A ratio, tissue Doppler velocity lateral and septal (é), E/é ratio, deceleration time of E, and isovolumic relaxation time) and myocardial deformation data (such as global radial and global and layer‐specific circumferential [endo and epi global CS] and longitudinal [endo and epi global LS] strain). Multivariate regression was used to assess the impact of independent variables on echocardiographic parameters. Results: Alcohol levels were 1.2 ± 0.3 g/L at the time of drinking cessation. After alcohol ingestion endo CS (30% ± 2% vs 37% ± 3%, P = .008) and endo LS (27% ± 4% vs 33% ± 3%, P = .002) were significantly lower at baseline versus follow‐up. Blood pressure, LVEF and heart rate, and other echocardiographic parameters did not differ between the two examinations. Alcohol levels were modestly, negatively associated with change in endo CS and endo LS (r = −0.54, 95% CI, −0.63 to −0.43, P < .001; and r = −0.26, 95% CI, −0.39 to −0.14; P < .003, respectively). Alcohol levels were the strongest predictor for endo CS (&bgr; = −4.84; 95% CI, −6.31 to −3.37) and endo LS (&bgr; = −2.50; 95% CI, −4.32 to −0.68). Conclusions: Acute alcohol ingestion effects endocardial CS and LS, suggesting an acute and transient toxic effect on myocardial deformation, an effect that remains undetected by conventional echocardiographic parameters. The current findings may help clinicians to gain more understanding into the mechanism of developing an alcohol cardiomyopathy and to detect early persistent alcohol‐induced myocardial disturbances for an effective therapy in time to prevent harm.