Noninvasive computerized acoustic cardiographic prediction of pulmonary hypertension

Poster Session 2 / Journal of Electrocardiology 42 (2009) 614–621 Methods: Using Cardiac Science Atria 6100s, we collected 426 resting electrocardiograms, sampled at 32/64 ksps and at 500 sps simultaneously, from 71 patients from 2 medical centers (1 in the United Kingdom and 1 in the United States). A variety of pacemakers from different vendors, including biventricular devices, was included. After annotating the pacer locations, we measured spike durations, amplitudes, atrio-ventricular (A-V), and atrio-biventricular (A-VV) delays from all 8 independent leads by using special viewing software. Results: The table below shows the mean (±SD) of spike data as well as polarity. Pacer type

Duration (ms)

Amplitude (mV)

Negative polarity (%)

Atrial Right ventricular only First ventricular of BiV Second ventricular of BiV All pacers

0.56 ± 0.10 0.56 ± 0.11 0.55 ± 0.08 0.60 ± 0.20 0.56 ± 0.12

3.04 ± 8.36 7.02 ± 14.28 3.66 ± 3.22 4.30 ± 5.03 4.88 ± 10.24

32 82 81 62 65

BiV indicates biventricular.

There are 47.29% of stimuli from all leads studied that have amplitudes less than 2 mV, 14.59% that have durations less than 0.5 milliseconds, and 51.53% that have either an amplitude or duration lower than these AAMI thresholds for detection/printing of pacemaker stimuli on an electrocardiogram report. The following table shows the mean (±SD) of time intervals. A-V delay (ms)

A-VV delay (ms)

Nonzero VV delay (ms)

206.86 ± 42.52

118.29 ± 17.13

2.5 (20%); 5.0 (80%)

Conclusion: Although durations of the various stimuli are stable, amplitudes exhibit large variations. More than half of all stimuli studied, atrial or ventricular, had an amplitude or duration below the detection thresholds that manufacturers can use to claim that their equipment meets current guidelines. These important results show that the current (2007) AAMI/IEC guidelines for pacemaker stimulus detection are not fit for purpose and require to be updated. doi:10.1016/j.jelectrocard.2009.08.035

Intravenous electrocardiographic guidance for placement of peripherally inserted central catheters Andrew D. Michaels, MD, MAS,a Renée M. Neuharth, BS,a Mary Ann Hendrix, RN,a,b Daniel McDonnall, PhD,b Scott Hiatt, MS,b ( aUniversity of Utah, Salt Lake City, Utah, USA; bRipple, LLC, Salt Lake City, Utah, USA) Background: Correct positioning of peripherally inserted central catheters (PICC) is essential to avoid complications such as perforation, thrombosis, or dysrhythmias caused by interactions with the vessel wall or the endocardium. Misplacement of catheter tip location occurs in roughly 20% of cases. The correct position of the catheter tip is in the superior vena cava (SVC) close to its entrance to the right atrium (RA). The most common way to assess catheter position is by radiographic assessment after placement. An alternative method for correct catheter

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placement is to record an intravascular electrocardiogram (ECG) from the catheter stylet. Using this technique, an increased P-wave amplitude provides verification that the intravascular catheter tip has passed into the RA. No commercial ECG-guidance system is available to US clinicians. We evaluated intravenous ECG recordings during PICC placement to assess the effectiveness of this guidance technique as a means to reduce complications resulting from incorrect catheter tip placement. Methods: Five of 10 adults undergoing PowerPICC catheter insertion have been enrolled. With the catheter in the SVC, venography was performed to identify the SVC-RA junction. Unipolar ECG recordings from the catheter stylet were performed at the SVC-RA junction and at 1-cm intervals when the catheter was inserted 5 cm into the RA and withdrawn 10 cm into the SVC. P-wave amplitude was recorded at each of these 16 recording sites. Results: Data are available from 5 subjects. Three underwent PICC placement via the right antecubital vein and 2 from the left upper extremity, without complications. The peak P-wave amplitude, normalized to the R wave, was highest at the SVC-RA junction (Table 1). With catheter insertion into the RA, P-wave amplitude decreased and eventually became negative. With catheter withdrawal into the SVC, P-wave amplitude decreased. Conclusions: P-wave amplitude was highest when the PICC catheter was at the optimal location. Intravenous ECG monitoring during PICC insertion seems to be a useful technique to guide catheter positioning. Further P-wave analysis, with incorporation of P-wave morphology, may also increase ECG-guided catheter insertion accuracy. doi:10.1016/j.jelectrocard.2009.08.036

Noninvasive computerized acoustic cardiographic prediction of pulmonary hypertension Andrew D. Michaels, MD, MAS,a Shadi Karabsheh, MD,a Renée M. Neuharth, BS,a Syed Masood, MD,a Patti Arand, PhD,b ( aUniversity of Utah, Salt Lake City, Utah, USA; bInovise Medical Inc., Portland, Oregon, USA) Background: The physical examination findings of an accentuated pulmonic component (P2) of the second heart sound (S2) and loud right ventricular third and fourth heart sound (RV S3 and S4) are associated with pulmonary hypertension (PH). However, there are limitations to the accuracy of physical examination findings for the diagnosis of PH. We sought to examine the association between computerized acoustic cardiographic assessment of these heart sounds and pulmonary artery systolic pressure (PASP) measured during right heart catheterization. We hypothesized that an accentuated S2, S3, and S4 over the pulmonic ausculatory region would correlate with PH. Methods: Fifty-six adults underwent contemporaneous right heart catheterization and acoustic cardiography. Acoustic sensors (Audicor; Inovise Medical Inc, Portland, OR) were placed over the standard positions used during cardiac auscultation: V3, V4, left sternal border in the third intercostal space, and right and left sternal borders in the second intercostal space. Computerized algorithms were used to assess the intensity of the four heart sounds (S1-S4). Correlation coefficients between acoustic parameters and PASP were calculated. Results: Twenty-eight (50%) subjects had a normal pulmonary artery mean (PAM) pressure (b25 mm Hg), 17 (30%) had mild PH (PAM 25-34 mm Hg), 10 (18%) had moderate PH (PAM 35-49 mm Hg), and 1 (2%)

Table 1 P-wave amplitude normalized to the R wave, by catheter location SVC

RA

10 cm

5 cm

3 cm

SVC-RA junction

3 cm

5 cm

0.18 ± 0.14⁎

0.31 ± 0.31⁎

0.46 ± 0.32

0.87 ± 0.15

−0.12 ± 0.44

−0.01 ± 0.46⁎

⁎ P b .05 versus SVC-RA junction.

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Poster Session 2 / Journal of Electrocardiology 42 (2009) 614–621

had severe PH (PAM ≥50 mm Hg). All patients had a sinus or paced atrial rhythm. There was a significant correlation coefficient between S2 intensity at the pulmonic area (left upper sternal border) and the PASP (r = 0.34; P = .0097). The correlation between PASP and S4 intensity at the left sternal border was significant (r = 0.37; P = .030). S3 intensity measured from the left sternal border was more weakly associated with PASP (r = 0.28; P = .037). The magnitude or variance of S2 splitting was not associated with PH. Conclusions: Computerized assessment of the S2, S3, and S4 intensities over the right ventricle correlates with invasive measurements of PASP. Further refinement of acoustic cardiography may serve as a noninvasive tool to assess the severity of PH. doi:10.1016/j.jelectrocard.2009.08.037

Evaluation of computer algorithm performance in culprit artery identification—comparison with expert readers' analysis in acute myocardial infarction Kjell Nikus,a Sophia Zhou,b Richard Gregg,b Ronald Startt-Selvester,c Yochai Birnbaum ,d ( aHeart Center, Tampere University Hospital, Tampere, Finland; bAdvanced Algorithm Research Center, Philips Healthcare, Thousand Oaks, CA, USA; cLong Beach Memorial Medical Center, Long Beach, CA, USA; dThe section of Cardiology, Baylor College of Medicine, Houston, TX, USA) Introduction: Morphologic electrocardiogram (ECG) analysis, including prediction of the culprit artery, is an essential part of the decision-making process in acute coronary syndromes (ACS). Computer-based diagnostic ECG algorithms may assist such analysis, especially in the Emergency Department and in the prehospital setting. This study compares the performance of two experienced electrocardiographers with newly developed computer algorithm in prediction of the infarct-related artery, as assessed by coronary angiography. Method: A total of 720 patients, admitted for definite or possible ACS, who underwent coronary angiography and had flow limiting lesions and recorded “infarct-related artery” were screened. Exclusion criteria were paced rhythm (n = 14), left bundle branch block (n = 33), left ventricular hypertrophy (n = 92), wide-complex tachycardia (n = 3), evolving MI and other Non-STEMI (n = 367) based on computer algorithm detection. The study population (n = 211) consists of patients with STEMI (n = 191) by the new AHA/ACC Guidelines, and Global subendocardial ischemia/MI (n = 20). Admission ECG (standard 12-leads + V4R, V8 and V8R) from each patient was analyzed by two experienced electrocardiographers (KN & YB) and also by Philips DXL algorithm. “Infarct-related artery” identified by coronary angiography served as “gold standard”. Result: Expert electrocardiographers' reading and DXL algorithm's result were tested against “infarct-related-artery (LAD, RCA, LCx, left main/ multivessel disease)” as identified by angiography and also compared with each other. Testing against the “Gold Standard”, the agreements are 74.9%, 74.4% and 78.7% for ECG expert 1, 2 and DXL respectively combining all culprit arteries. Among the STEMI and Global Ischemia cases as agreed by both, the two experts reached an agreement of 91% (159/175). The DXL

CL (ms) 1/CL (Hz) f0 (Hz) fd (Hz) Pn(f0) (×1000) Pn(fd) (×1000) Oi Ri Mi

algorithm reached 85% (155/182) and 84% (158/188) agreement with both experts respectively. Conclusion: The computer algorithm performance was comparable to those of expert electrocardiographers. The Philips DXL algorithm performance in comparison with experienced ECG experts showed promising results in predicting culprit artery in ACS.

doi:10.1016/j.jelectrocard.2009.08.038

Fundamental frequency and regularity of cardiac electrograms with Fourier organization analysis Óscar Barquero-Pérez,a José Luis Rojo-Álvarez,a Rebeca Goya-Esteban,a Felipe Alonso-Atienza,a J.J. Sánchez-Muñoz,b Jesús Requena-Carrión,a Arcadi García-Alberola,b ( aDepartment of Signal Theory and Communications, University Rey Juan Carlos, Madrid, Spain; bUnit of Arrhythmias, Hospital Universitario Virgen de la Arrixaca, Murcia, Spain) Background: Dominant frequency analysis (DFA) and spectral organization analysis on cardiac electrograms (EGM) are receiving much attention to establish clinical targets for cardiac arrhythmia ablation. However, previous spectral descriptions of the EGM have been constrained to the 0to 30-Hz band; in doing so, they often discard relevant information, as the harmonic structure, the spectral envelope, or the presence of several organized mechanisms. Objective: Our aim was to give a full-band description of the spectral features in EGM recordings that accounts for the information contained in their harmonic structure. Methods: A simulation computer model was used to generate unipolar and bipolar EGM in the following conditions: plane wavefront, singleand multiple-focal activity, anchored rotor, and fibrillatory activity. For these simulated EGM, a full-band spectral description was obtained, which consisted of parameters measuring periodicity (cycle length [CL], fundamental [fo], and dominant frequency [fd]), spectral envelope (normalized power peaks [Pn]), organization (organization [oi] and regularity index [ri]). The possible presence of several physiologically independent components was considered for the first time in this setting (multiplicity index [mi]). Results: In the presence of harmonic structure, averaged cycle length was more clearly determined when using fundamental frequency, rather than dominant frequency. Spectral envelope was modified by both the acquisition lead system configuration and the nature of the underlying electrophysiologic process. Finally, indices for quantifying organization were strongly sensitive to the consideration of the harmonic structure in their definition. Conclusion: The consideration of full-band spectral descriptions, specially the existence of clear interharmonic spectral structure and multiple fundamental components, can make the spectral measurements currently used for dominant frequency analysis and organization analysis more robust. doi:10.1016/j.jelectrocard.2009.08.039

Plane wavefront

Focal activation

Anchored rotor

Fibrillatory

Double focal

Bipolar

Unipolar

Bipolar

Unipolar

Bipolar

Unipolar

Bipolar

Unipolar

Bipolar

Unipolar

400 2.5 2.54 5.08 8 32 0.80 0.25 –

400 2.5 2.54 4.98 42 54 0.95 0.47 –

400 2.5 2.44 4.98 15 38 0.89 0.31 –

400 2.5 2.44 4.98 48 56 0.98 0.51 –

250 4 4.00 4.00 39 39 0.62 0.31 –

250 4 4.00 4.00 95 95 0.83 0.72 –

125 8 5.18 7.32 5 51 0.26 0.43 –

143 6.9 5.18 7.42 12 39 0.36 0.34 –

181 5.52 5.66 5.57 56 56 0.67 0.55 0.96

153 6.53 5.66 5.76 54 57 0.58 0.46 0.96