Peter Fenici

A survey of the in-hospital response to cardiac arrest on general wards in the hospitals of Rome

OBJECTIVE To investigate the response to cardiac arrest in general wards. METHODS Direct interview with the cardiac arrest team (CAT) members in 32 hospitals in Rome, Italy. RESULTS The majority of CATs are activated by telephone but only two (6%) hospitals have a dedicated telephone number for emergency calls. The CAT always includes a physician, who is usually an anaesthesiologist (30 hospitals, 94%), and usually includes one or two other members (23 hospitals, 72%). In 21 hospitals (65%) there is less than one defibrillator per floor but in only six hospitals (19%), CATs are equipped with defibrillators. Resuscitation guidelines are adopted by 15 teams (47%). The Utstein style of data collection is used in only one hospital. The most common problems reported by the CATs are: insufficient training of ward personnel (29 hospitals, 91%), insufficient staff (19 hospitals, 59%) and insufficient equipment (18 hospitals, 56%). Average maximum arrival time for the CAT to arrive is 220 s, but varies significantly between single-building and the multiple-building hospitals (88 vs. 390 s; P<0.001). CONCLUSIONS The majority of the cardiac arrest teams have acceptable response times, but their efficiency may be impaired by the lack of staff, equipment and co-ordination with the ward personnel. CAT members identified a strong need for BLS training of ward personnel. More widespread introduction of standard protocols for resuscitation and reporting of cardiac arrest are necessary to evaluate aspects that may need improvement.

What is the optimal chest compression-ventilation ratio?

Purpose of reviewDespite a more widespread knowledge of basic cardiopulmonary resuscitation maneuvers in the community, the survival rate for patients with cardiac arrest has remained essentially unchanged in the past 30 years. Over the past few decades, many different compression-ventilation ratios have been studied in terms of best coronary and cerebral oxygen delivery, restoration of spontaneous circulation, and neurologic outcome. This article summarizes the recent evidence presented at the International Consensus on Resuscitation Science in January 2005. Recent findingsRecent data from animal and mathematical models suggest a move to a higher compression-ventilation ratio to maximize coronary and cerebral oxygen delivery during cardiac arrest and long-term neurologic outcome. Prospective randomized human data on alternative compression-ventilation ratios are missing and new evidence seems to indicate the inadequacy of both lay and professional rescuers in providing chest compression and ventilating the victim in cardiac arrest. Finally, observational and animal studies highlight the hidden danger of inadvertent hyperventilation during advanced cardiac life support as a reduction of both coronary and perfusion pressure secondary to increased intrathoracic pressure and decreased venous return. SummaryThe optimal compression-ventilation ratio is still unknown and the best tradeoff between oxygenation and organ perfusion during cardiopulmonary resuscitation is probably different for each patient and scenario. A discrepancy between what is recommended by the current guidelines and the ‘real world’ of cardiopulmonary resuscitation has resulted in a near flat survival rate from cardiac arrest in the past few years.

Phantom validation of multichannel magnetocardiography source localization

FENICI, R., et al.: Phantom Validation of Multichannel Magnetocardiography Source Localization. Multichannel magnetocardiography (MMCG) is used clinically for noninvasive localization of the site of origin of cardiac arrhythmias. However, its accuracy in unshielded environments is still unknown. The aim of this study was to test the accuracy of three‐dimensional localization of intracardiac sources by means of MMCG in an unshielded catheterization laboratory using a saline‐filled phantom, together with a nonmagnetic catheter designed for multiple monophasic action potential recordings in a clinical setting. A nine‐channel direct current superconducting quantum interference device (DC‐SQUID) system (sensitivity fT/Hz0.5) was used for MMCG from 36 points in a measuring area of 20 × 20 cm. The artificial sources to be localized were dipoles embedded in the distal end of the catheter, placed 12 cm below the sensors plane. Equivalent current dipoles, effective magnetic dipoles, and distributed currents models were used for the inverse solution. The localization error was estimated as the three‐dimensional difference between the physical position of the tip of the catheter and the three‐dimensional localization of the dipoles derived by means of the inverse solution calculated from MMCG data. The reproducibility was tested by repeating the MMCG after repositioning the phantom and the measurement system. The average location error of the catheter dipole was 9 ± 4 mm and was due primarily to imprecise depth estimation. Localization was reproducible within 0.73 mm. The distributed currents model provided an accurate image of current distribution centered over the catheter tip. The authors conclude that MMCG estimation is accurate enough to guarantee proper localization of cardiac dipolar sources even in an unshielded clinical electrophysiological laboratory. (PACE 2003; 26[Pt. II]:426–430)

Nonfluoroscopic Localization of an Amagnetic Catheter in a Realistic Torso Phantom by Magnetocardiographic and Body Surface Potential Mapping

This study was performed to evaluate the accuracy of multichannel magnetocardiographic (MCG) and body surface potential mapping (BSPM) in localizing three‐dimensionally the tip of an amagnetic catheter for electrophysiology without fluoroscopy. An amagnetic catheter (AC), specially designed to produce dipolar sources of different geometry without magnetic disturbances, was placed inside a physical thorax phantom at two different depths, 38 mm and 88 mm below the frontal surface of the phantom. Sixty‐seven MCG and 123 BSPM signals generated by the 10 mA current stimuli fed into the catheter were then recorded in a magnetically shielded room. Non‐invasive localization of the tip of the catheter was computed from measured MCG and BSPM data using an equivalent current dipole source in a phantom‐specific boundary element torso model. The mean 3‐dimensional error of the MCG localization at the closer level was 2 ± 1 mm. The corresponding error calculated from the BSPM measurements was 4 ± 1 mm. At the deeper level, the mean localization errors of MCG and BSPM were 7 ± 4 mm and 10 ± 2 mm, respectively. The results showed that MCG and BSPM localization of the tip of the AC is accurate and reproducible provided that the signal‐to‐noise ratio is sufficiently high. In our study, the MCG method was found to be more accurate than BSPM. This suggests that both methods could be developed towards a useful clinical tool for nonfluoroscopic 3‐dimensional electroanatomical imaging during electrophysiological studies, thus minimizing radiation exposure to patients and operators.

Magnetocardiographic Pacemapping for Nonfluoroscopic Localization of Intracardiac Electrophysiology Catheters

The purpose of the study was to validate, in patients, the accuracy of magnetocardiography (MCG) for three‐dimensional localization of an amagnetic catheter (AC) for multiple monophasic action potential (MAP) with a spatial resolution of 4 mm2. The AC was inserted in five patients after routine electrophysiological study. Four MAPs were simultaneously recorded to monitor the stability of endocardial contact of the AC during the MCG localization. MAP signals were band‐pass filtered DC‐500 Hz and digitized at 2 KHz. The position of the AC was also imaged by biplane fluoroscopy (XR), along with lead markers. MCG studies were performed with a multichannel SQUID system in the Helsinki BioMag shielded room. Current dipoles (5mm; 10mA), activated at the tip of the AC, were localized using the equivalent current dipole (ECD) model in patient‐specific boundary element torso. The accuracy of the MCG localizations was evaluated by: (1) anatomic location of ECD in the MRI, (2) mismatch with XR. The AC was correctly localized in the right ventricle of all patients using MRI. The mean three‐dimensional mismatch between XR and MCG localizations was 6 ± 2 mm (beat‐to‐beat analysis). The coefficient of variation of three‐dimensional localization of the AC was 1.37% and the coefficient of reproducibility was 2.6 mm. In patients, in the absence of arrhythmias, average local variation coefficients of right ventricular MAP duration at 50% and 90% ofrepolarization, were 7.4% and 3.1%, respectively. This study demonstrates that with adequate signal‐to‐noise ratio, MCG three‐dimensional localizations are accurate and reproducible enough to provide nonfluoroscopy dependant multimodal imaging for high resolution endocardial mapping of monophasic action potentials.

Noninvasive Study of Ventricular Preexcitation Using Multichannel Magnetocardiography

FENICI, R., et al.: Noninvasive Study of Ventricular Preexcitation Using Multichannel Magnetocardiography. In clinical practice, noninvasive classification of ventricular preexcitation (VPX) is usually done with ECG algorithms, which provide only a qualitative localization of accessory pathways. Since 1984, single or multichannel magnetocardiograpy (MMCG) has been used for three‐dimensional localization of VPX sites, but a systematic study comparing the results of ECG and MMCG methods was lacking. This study evaluated the reliability of MMCG in an unshielded electrophysiological catheterization laboratory, and compared VPX classification as achieved with the five most recent ECG algorithms with that obtained by MMCG mapping and imaging techniques. A nine‐channel direct current superconducting quantum interference device (DC‐SQUID) MMCG system (sensitivity is 20 fT/Hz0.5) was used for sequential MMCG from 36 points on the anterior chest wall, within an area 20 × 20 cm . Twenty‐eight patients with Wolff‐Parkinson‐White syndrome were examined at least twice, on the same day or after several months to test the reproducibility of the measurements. In eight patients, the reproducibility of MMCG was also evaluated using different MCG instrumentation during maximal VPX and/or atrioventricular reentrant tachycardia induced by transesophageal atrial pacing via a nonmagnetic catheter. The results of VPX localization with ECG algorithms and MMCG were compared. Equivalent current dipole, effective magnetic dipole, and distributed currents imaging models were used for the inverse solution. MMCG classification of VPX was found to be more accurate than ECG methods, and also provided additional information for the identification of paraseptal pathways. Furthermore, in patients with complex activation patterns during the delta wave, distributed currents imaging revealed two different activation patterns, suggesting the existence of multiple accessory pathways. (PACE 2003; 26[Pt. II]:431–435)

Enoximone in cardiac arrest caused by propranolol: two case reports.

We report two clinical cases of cardiac arrest, the former due to an adverse effect of intravenous (i.v.) propranolol in a patient with systemic sclerosis, the latter from a propranolol suicidal overdose. In both cases, conventional advanced life support (ALS) was ineffective but both patients eventually responded to the administration of enoximone, a phosphodiesterase III (PDE III) inhibitor. After the arrest, both patients regained consciousness and were discharged home. The chronotropic and inotropic effects of PDE III inhibitors are due to inhibition of intracellular PDEIII and are therefore unaffected by beta‐blockers. These cases suggest that PDEIII inhibitors may be useful in restoring spontaneous circulation in cardiac arrest associated with beta‐blocker administration when standard ALS is ineffective.

Clinical validation of machine learning for automatic analysis of multichannel magnetocardiography

Magnetocardiographic (MCG) mapping measures magnetic fields generated by the electrophysiological activity of the heart. Quantitative analysis of MCG ventricular repolarization (VR) parameters may be useful to detect myocardial ischemia in patients with apparently normal ECG. However, manual calculation of MCG VR is time consuming and can be dependent on the examiner’s experience. Alternatively, the use of machine learning (ML) has been proposed recently to automate the interpretation of MCG recordings and to minimize human interference with the analysis. The aim of this study was to validate the predictive value of ML techniques in comparison with interactive, computer-aided, MCG analysis. ML testing was done on a set of 140 randomly analysed MCG recordings from 74 subjects: 41 patients with ischemic heart disease (IHD) (group 1), 32 of them untreated (group 2), and 33 subjects without any evidence of cardiac disease (group 3). For each case at least 2 MCG datasets, recorded in different sessions, were analysed. Two ML techniques combined identified abnormal VR in 25 IHD patients (group 1) and excluded VR abnormalities in 28 controls (group 3) providing 75% sensitivity, 85% specificity, 83% positive predictive value, 78% negative predictive value, 80% predictive accuracy This result was for the most part in agreement, but statistically better than that obtained with interactive analysis. This study confirms that ML, applied on MCG recording at rest, has a predictive accuracy of 80% in detecting electrophysiological alterations associated with untreated IHD. Further work is needed to test the ML capability to differentiate VR alterations due to IHD from those due to non-ischemic cardiomyopathies.