Comparison between two defibrillation waveforms.

Two defibrillation waveforms, the chopped biphasic pulses and the constant current pulses, were assessed and compared. Two indices are introduced. The first one is the ratio between the delivered energy W and the energy W(0) of a rectangular pulse with the same duration and electric charge. The second index η(C) = W(0)/W(C0) stands for the level of utilizing the initially loaded capacitor energy W(C0). Some design considerations are also discussed. Another aspect of the study is the choice of appropriate capacitor for pulse generation. The results obtained show that there is no outstanding optimal waveform. The W/W(0) ratio is higher for the known constant current shapes but specifically with a patient resistance lower than 80 Ω. On the other hand, the implementation of these shapes would face several difficulties. The chopped biphasic waveforms are obtained by relatively simple technical solutions leading to very small in size and weight portable instruments.

Shock advisory system for heart rhythm analysis during cardiopulmonary resuscitation using a single ECG input of automated external defibrillators.

Minimum "hands-off" intervals during cardiopulmonary resuscitation (CPR) are required to improve the success rate of defibrillation. In support of such life-saving practice, a shock advisory system (SAS) for automatic analysis of the electrocardiogram (ECG) contaminated by chest compression (CC) artefacts is presented. Ease of use for the automated external defibrillators (AEDs) is aimed and therefore only processing of ECG from usual defibrillation pads is required. The proposed SAS relies on assessment of outstanding components of ECG rhythms and CC artefacts in the time and frequency domain. For this purpose, three criteria are introduced to derive quantitative measures of band-pass filtered CC-contaminated ECGs, combined with three more criteria for frequency-band evaluation of reconstructed ECGs (rECG). The rECGs are derived by specific techniques for CC waves similarity assessment and are reproducing to some extent the underlying ECG rhythms. The rhythm classifier embedded in SAS takes a probabilistic decision designed by statistics on the training dataset. Both training and testing are fully performed on real CC-contaminated strips of 10 s extracted from human ECGs of out-of-hospital cardiac arrest interventions. The testing is done on 172 shockable strips (ventricular fibrillations VF), 371 non-shockable strips (NR) and 330 asystoles (ASYS). The achieved sensitivity of 90.1% meets the AHA performance goal for noise-free VF (>90%). The specificity of 88.5% for NR and 83.3% for ASYS are comparable or even better than accuracy reported in literature. It is important to note that, the aim of this SAS is not to recommend shock delivery but to advice the rescuers to "Continue CPR" or to "Stop CPR and Prepare for Shock" thus minimizing "hands-off" intervals.

Electrochemotherapy for the treatment of squamous cell carcinoma in cats: a preliminary report.

Squamous cell carcinomas (SCC) of the skin are commonly described in cats. Reported treatments include surgery, radiation therapy and photodynamic therapy. This preliminary study reports on the management of these lesions combining the local administration of bleomycin (plus hyaluronidase for a more uniform distribution) with permeabilizing biphasic electric pulses. Nine cats with SCC graded T(2)-T(4) were treated over a 5 year period, and each cat received two sessions of electrochemotherapy (ECT) 1 week apart. The side effects of this treatment were minimal and limited to mild erythema of the nose. Seven of the cats (77.7%) had a complete response lasting up to 3 years. ECT seems to be a safe and effective option for the treatment of feline sun-induced squamous cell carcinomas and warrants further investigation.

Biphasic pulses enhance bleomycin efficacy in a spontaneous canine genital tumor model of chemoresistance: Sticker sarcoma.

Sticker's sarcoma (also known as transmissible venereal tumor) is a horizontally transmitted neoplasm of the dog, that is passed with coitus. It is a locally aggressive tumor with a low tendency to metastatic spread. The most common locations are the genitals, the nose, the perianal area. Standard treatment consists with chemotherapy with vincristine, however other therapies such as, cryotherapy, immunotherapy or, in selected cases, radiation therapy, have been reported. In this article we describe the outcome of a small cohort of canine patients, with chemotherapy resistant transmissible venereal tumor (TVT), treated with bleomycin selectively driven by trains of biphasic pulses (electrochemotherapy). Three canine patients, with refractory TVT, entered the study and received two sessions of ECT under sedation. The pets had local injection of bleomycin at the concentration of 1.5 mg/ml and five minutes after the chemotherapy, trains of 8 biphasic electric pulses lasting 50 + 50 mus each, with 1 ms interpulse intervals, were delivered by means of modified caliper or, for difficult districts, through paired needle electrode. All the patients responded to the treatment and are still in remission at different times. Electrochemotherapy appears as a safe and efficacious modality for the treatment of TVT and warrants further investigations.

Tremor suppression in ECG.

BACKGROUND: Electrocardiogram recordings are very often contaminated by high-frequency noise usually power-line interference and EMG disturbances (tremor). Specific method for interference cancellation without affecting the proper ECG components, called subtraction procedure, was developed some two decades ago. Filtering out the tremor remains a priori partially successful since it has a relatively wide spectrum, which overlaps the useful ECG frequency band. METHOD: The proposed method for tremor suppression implements the following three procedures. Contaminated ECG signals are subjected to moving averaging (comb filter with linear phase characteristic) with first zero set at 50 Hz to suppress tremor and PL interference simultaneously. The reduced peaks of QRS complexes and other relatively high and steep ECG waves are then restored by an introduced by us procedure called linearly-angular, so that the useful high frequency components are preserved in the range specified by the embedded in the ECG instrument filter, usually up to 125 Hz. Finally, a Savitzky-Golay smoothing filter is applied for supplementary tremor suppression outside the QRS complexes. RESULTS: The results obtained show a low level of the residual EMG disturbances together with negligible distortion of the wave shapes regardless of rhythm and morphology changes.

Adjuvant electrochemotherapy for incompletely excised anal sac carcinoma in a dog.

Canine anal sac gland carcinoma (ASGC) is a frequently described neoplasm that is highly aggressive and can frequently lead to metastatic spread. In this paper, we describe the successful treatment of an incompletely excised ASGC by using cisplatin selectively driven within the tumor cells by trains of biphasic pulses. The dog received two courses of electrochemotherapy 14 days apart. Neither systemic nor local toxicities were detected during the whole course of therapy. The dog is still in complete remission after 18 months. Electrochemotherapy is a safe and efficacious adjuvant therapy for ASGC and warrants further investigation in order to standardize its protocols.

Successful rescue of an apocrine gland carcinoma metastatic to the cervical lymph nodes by mitoxantrone coupled with trains of permeabilizing electrical pulses (electrochemotherapy).

Canine apocrine gland carcinoma is a locally aggressive neoplasm that can occasionally lead to metastatic spread, thus mimicking the behavior of their human counterpart. In this paper we describe the successful treatment of a cervical metastatic spread of this neoplasia by using mitoxantrone selectively driven within the tumor cells by trains of biphasic pulses. The dog experienced tumor reduction from the first cycle of electrochemotherapy (ECT) and complete remission by the time of its fourth session. Neither systemic or local toxicities were detected during the whole course of therapy. The dog is in complete remission after six months from his last treatment. Electrochemotherapy is a safe and efficacious therapy for metastatic carcinoma and warrants further investigation.

Ganglioneuroblastoma in a cat: a rare neoplasm treated with electrochemotherapy.

An 8-year-old male castrated cat was referred for sudden onset of lameness. Physical examination revealed a 1x2x1cm mass originating from a footpad of the right hind leg. A diagnosis of ganglioneuroblastoma was suggested by the tumour appearance following histopathological staining with haematoxylin and eosin and haematoxylin/van Gieson. Immunohistochemical staining for glial fibrillary acidic protein (GFAP), vimentin, neuron-specific enolase (NSE), neurofilament and S100 further confirmed the diagnosis. The staging process did not indicate metastatic spread. The cat was treated with three sessions of electrochemotherapy (ECT) 1 week apart, following local injection of bleomycin. The tumour had completely regressed within 1 week of the third ECT application and remained in remission for 402 days at which time a small recurrence was noted. The animal was given a further session of ECT using intra-lesional cisplatin and again went into remission. It remained tumour free at 450 days. Electrochemotherapy is considered a safe and effective treatment for localised neoplasms of cats and dogs and warrants further investigation.

Electrochemotherapy-induced radiation recall in a cat.

Electrochemotherapy is gaining popularity for the treatment of malignancies of companion animals due to its efficacy and low cost. In this paper, we describe the successful treatment of a recurring fibrosarcoma in a cat by using cisplatin selectively driven within the tumor cells by trains of biphasic pulses. The cat's tumor did not recur over the following five months, however the cat did experience severe erythema at the site of previous irradiation, followed by moist desquamation and ulcer that required debridement and prolonged therapy with steroids and antihistaminic drugs. The symptoms and the response to symptomatic therapy were strongly suggestive of radiation recall. Electrochemotherapy (ECT) should be used with caution in previously irradiated areas. Further studies are warranted in this field due to its potential as a rescue for relapsing tumors.

Adjuvant electrochemotherapy for the treatment of incompletely excised spontaneous canine sarcomas.

Electrochemotherapy (ECT) is a new therapeutical technique that combines the administration of trains of biphasic pulses with the local application of poorly permeant anticancer molecules, thus obtaining increased chemotherapy uptake. The purpose of this study was to prospectively assess the adjuvant potentialities of ECT for the treatment of different incompletely excised canine sarcomas. Twenty-two privately owned dogs with incomplete surgical excision of high grade sarcomas were treated with bleomycin injected within the tumor bed (1.5 IU/mg) followed by the sequential application of trains of biphasic pulses (8 pulses, 1300 V/cm, 50+50 micros duration, 1 Hz frequency). The overall response rate was 95% (21 out of 22 patients) with a mean time to recurrence of 730 days. At the time of writing 11 dogs were still in remission, three dogs had died of unrelated causes, one had local recurrence and the owner declined further treatment, one had limb amputation following recurrence, four had both local recurrence and distant metastases that led to euthanasia, and two were retreated following tumor recurrence and are disease free at 850 and 1947 days. The only observed toxicity was wound dehiscence in three patients. Electrochemotherapy is well tolerated and has effectiveness against incompletely excised sarcomas in companion animals. Further investigations are warranted to improve the currently available protocols.

Local control and distant metastasis after electrochemotherapy of a canine anal melanoma.

Canine anal melanoma is an aggressive neoplasm that rapidly leads to constipation in dogs, thus mimicking the behavior of their human counterpart. In this paper, the successful local palliation of this neoplasm is described using cisplatin selectively driven within the tumor cells by trains of biphasic pulses. The dog experienced tumor reduction with restoration of normal defecation for three months, then experienced massive dissemination to the sublumbar lymph nodes that led to intestinal obstruction and euthanasia. Electrochemotherapy (ECT) is a safe palliative therapy for such neoplasm and warrants further investigations in dogs as well humans.

Atrial wave detection algorithm for discovery of some rhythm abnormalities.

Atrial flutter (AFL) and atrial fibrillation (AF) generate patterns in the electrocardiogram, which have some similarity to a normal P-wave. Therefore their detection is an important step of AFL/AF recognition as well as P-wave detection is for AV block identification. Many approaches to P-wave identification are based on correlation with a manually selected template. The developed method and algorithm use a universal synthesized template and apply a modified convolution for P-wave detection. In order to emphasize the true coincidences, the sample differences between the template and P-wave candidates are introduced in a denominator. Each convolution is calculated twice with a shifted template, which locates once its first term closely to the corresponding signal sample and secondly does the same with its middle term. The convolution sum is compared with adaptive threshold Tr to mark P-wave occurrences. To accelerate the computation process, the two convolutions are accomplished only if a preliminary convolution over a reduced number of samples gives an outcome higher than the decreased threshold Tr/2. Further, a rule for AF recognition is applied. The results show that missed or wrong P-wave detections are observed in a limited number of RR intervals. They do not hamper the discovery of AFL/AF arrhythmias. The algorithm can be successfully used for such cases except for prediction of paroxysmal AF. The mean delay in AF onset recognition over a 10 h recording taken from MIT-BIH-Afdb is 2.7 s. This value for AF offset is 5.5 s. As a QRS detector is a part of the P-wave detection algorithm, both of them may be applied also for AV block identification.

Dataset of manually measured QT intervals in the electrocardiogram.

BACKGROUND: The QT interval and the QT dispersion are currently a subject of considerable interest. Cardiac repolarization delay is known to favor the development of arrhythmias. The QT dispersion, defined as the difference between the longest and the shortest QT intervals or as the standard deviation of the QT duration in the 12-lead ECG is assumed to be reliable predictor of cardiovascular mortality. The seventh annual PhysioNet/Computers in Cardiology Challenge, 2006 addresses a question of high clinical interest: Can the QT interval be measured by fully automated methods with accuracy acceptable for clinical evaluations? METHOD: The PTB Diagnostic ECG Database was given to 4 cardiologists and 1 biomedical engineer for manual marking of QRS onsets and T-wave ends in 458 recordings. Each recording consisted of one selected beat in lead II, chosen visually to have minimum baseline shift, noise, and artifact.In cases where no T wave could be observed or its amplitude was very small, the referees were instructed to mark a 'group-T-wave end' taking into consideration leads with better manifested T wave.A modified Delphi approach was used, which included up to three rounds of measurements to obtain results closer to the median. RESULTS: A total amount of 2*5*548 Q-onsets and T-wave ends were manually marked during round 1. To obtain closer to the median results, 8.58 % of Q-onsets and 3.21 % of the T-wave ends had to be reviewed during round 2, and 1.50 % Q-onsets and 1.17 % T-wave ends in round 3. The mean and standard deviation of the differences between the values of the referees and the median after round 3 were 2.43 +/- 0.96 ms for the Q-onset, and 7.43 +/- 3.44 ms for the T-wave end. CONCLUSION: A fully accessible, on the Internet, dataset of manually measured Q-onsets and T-wave ends was created and presented in additional file: 1 (Table 4) with this article. Thus, an available standard can be used for the development of automated methods for the detection of Q-onsets, T-wave ends and for QT interval measurements.

Suppression of AC railway power-line interference in ECG signals recorded by public access defibrillators.

BACKGROUND: Public access defibrillators (PADs) are now available for more efficient and rapid treatment of out-of-hospital sudden cardiac arrest. PADs are used normally by untrained people on the streets and in sports centers, airports, and other public areas. Therefore, automated detection of ventricular fibrillation, or its exclusion, is of high importance. A special case exists at railway stations, where electric power-line frequency interference is significant. Many countries, especially in Europe, use 16.7 Hz AC power, which introduces high level frequency-varying interference that may compromise fibrillation detection. METHOD: Moving signal averaging is often used for 50/60 Hz interference suppression if its effect on the ECG spectrum has little importance (no morphological analysis is performed). This approach may be also applied to the railway situation, if the interference frequency is continuously detected so as to synchronize the analog-to-digital conversion (ADC) for introducing variable inter-sample intervals. A better solution consists of rated ADC, software frequency measuring, internal irregular re-sampling according to the interference frequency, and a moving average over a constant sample number, followed by regular back re-sampling. RESULTS: The proposed method leads to a total railway interference cancellation, together with suppression of inherent noise, while the peak amplitudes of some sharp complexes are reduced. This reduction has negligible effect on accurate fibrillation detection. CONCLUSION: The method is developed in the MATLAB environment and represents a useful tool for real time railway interference suppression.

Removal of power-line interference from the ECG: a review of the subtraction procedure.

BACKGROUND: Modern biomedical amplifiers have a very high common mode rejection ratio. Nevertheless, recordings are often contaminated by residual power-line interference. Traditional analogue and digital filters are known to suppress ECG components near to the power-line frequency. Different types of digital notch filters are widely used despite their inherent contradiction: tolerable signal distortion needs a narrow frequency band, which leads to ineffective filtering in cases of larger frequency deviation of the interference. Adaptive filtering introduces unacceptable transient response time, especially after steep and large QRS complexes. Other available techniques such as Fourier transform do not work in real time. The subtraction procedure is found to cope better with this problem. METHOD: The subtraction procedure was developed some two decades ago, and almost totally eliminates power-line interference from the ECG signal. This procedure does not affect the signal frequency components around the interfering frequency. Digital filtering is applied on linear segments of the signal to remove the interference components. These interference components are stored and further subtracted from the signal wherever non-linear segments are encountered. RESULTS: Modifications of the subtraction procedure have been used in thousands of ECG instruments and computer-aided systems. Other work has extended this procedure to almost all possible cases of sampling rate and interference frequency variation. Improved structure of the on-line procedure has worked successfully regardless of the multiplicity between the sampling rate and the interference frequency. Such flexibility is due to the use of specific filter modules. CONCLUSION: The subtraction procedure has largely proved advantageous over other methods for power-line interference cancellation in ECG signals.

Ventricular beat detection in single channel electrocardiograms.

BACKGROUND: Detection of QRS complexes and other types of ventricular beats is a basic component of ECG analysis. Many algorithms have been proposed and used because of the waves' shape diversity. Detection in a single channel ECG is important for several applications, such as in defibrillators and specialized monitors. METHODS: The developed heuristic algorithm for ventricular beat detection includes two main criteria. The first of them is based on steep edges and sharp peaks evaluation and classifies normal QRS complexes in real time. The second criterion identifies ectopic beats by occurrence of biphasic wave. It is modified to work with a delay of one RR interval in case of long RR intervals. Other algorithm branches classify already detected QRS complexes as ectopic beats if a set of wave parameters is encountered or the ratio of latest two RR intervals RRi-1/RRi is less than 1:2.5. RESULTS: The algorithm was tested with the AHA and MIT-BIH databases. A sensitivity of 99.04% and a specificity of 99.62% were obtained in detection of 542014 beats. CONCLUSION: The algorithm copes successfully with different complicated cases of single channel ventricular beat detection. It is aimed to simulate to some extent the experience of the cardiologist, rather than to rely on mathematical approaches adopted from the theory of signal analysis. The algorithm is open to improvement, especially in the part concerning the discrimination between normal QRS complexes and ectopic beats.