Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Defibrillators”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,315 records · Page 73Linked to original sources

Automatic external defibrillators in the hospital as well?

When a cardiac arrest occurs in a non-intensive area of the hospital, the emergency response is not always adequate from the point of view of timeliness and technical quality. The aims of this study were evaluate an experimental programme to improve the CPR skills of staff operating in non-intensive areas of our general hospital and to test the usefulness of placing automatic external defibrillators (AEDs) within these areas. In the experimental phase, two AEDs were placed in 2 non-intensive wards of our hospital for 8 months. The staff of these wards received specific training in CPR and early defibrillation (CPR-D). The devices were used in 19 cases; for defibrillation in four cases of ventricular fibrillation (VF) (three patients were discharged alive from hospital), and for monitoring three supraventricular arrhythmias, one bradyarrhythmia and 11 cardiac rhythms during critical situations. In the implementation phase, four AEDs were indefinitely assigned to as many non-intensive awards. Periodical CPR-D courses and refresher exercises were run; the cardiology staff co-operated in the maintenance of the AEDs and in the registration of technical and clinical data. In the first period of this phase (9 months), AEDs were utilized in 24 cases by the ward-staff: in nine cases for VF (three patients were discharged alive from hospital) and in 15 cases for other rhythm detection in critical conditions. The number and the quality of these uses seem to confirm the favourable impact of the adoption of a more user-friendly defibrillator, such as an AED. The active co-operation between intensive and non-intensive staff was important to facilitate a quick activation of the chain of survival outside the intensive care units. We conclude that AEDs, which were developed for out-of-hospital use by non-physician operators, are suitable for use inside the hospital as well.

Adult↗

Comparative assessment of shockable ECG rhythm detection algorithms in automated external defibrillators.

The sensitivity and specificity to ventricular fibrillation (VF) and ventricular tachycardia (VT), classified as requiring immediate DC shock, of four automated external defibrillators (AEDs) and three advisory defibrillators were assessed using the Department of Health Arrhythmia library. This library collected mostly from patients in hospital, includes a wide variety of ECG rhythms including many with additional noise and interference artefact. The library comprised 278 16-s rhythms, 59 of which were VF, 36 were VT requiring cardioversion and 183 were deemed non-shockable. Non-shockable rhythms included asystole, pacing, slow VT, idioventricular rhythms, sinus and atrial based rhythms, some of which contained ventricular ectopic activity of differing grades. For the AEDs, a positive result (indicating detection of a shockable rhythm) was recorded if charging started or was able to be started at any time during the 16 s of rhythm output and energy subsequently available for discharge. For the advisory defibrillators, a positive result was recorded if a 'shock advised' alert was issued at any time during output of the rhythm. The AEDs exhibited sensitivities to VF in the range 81-94%, and to VF plus shockable VT 64-73%, or 72-83% depending whether VT > 150 beats/min or > 180 beats/min is considered to be shockable. The specificities recorded were in the range 90-94% and 86-92%, respectively. All but one of the advisory defibrillators performed similarly. Excluding the artefact rhythms, specificities in the range 79-91% were obtained. All figures stated are at the lower limit of the 95% confidence interval.

Algorithms↗

Current-based versus energy-based ventricular defibrillation: a prospective study.

Defibrillation is thought to be mediated by a depolarizing current; however, the present method of defibrillation is based on delivering an empiric dose of energy to all patients. The hypothesis of this study was that for equivalent efficacy rates, a current-based defibrillation method would result in delivering less energy and peak current than would the standard energy-based method. In a group of 86 consecutive patients with ventricular fibrillation, every other patient was prospectively assigned to receive shocks according to method 1 or method 2. Method 1 was current based and delivered successive shocks of 25, 25 and a maximum of 40 A; method 2 was energy based and delivered shocks of 200, 200 and 360 joules. Patients in both groups were similar with respect to age, gender, weight, cardiac diagnosis, ejection fraction, antiarrhythmic therapy, chest circumference, chest depth and transthoracic impedance. Each method had statistically equivalent first shock (79% current-based versus 81% energy-based) and cumulative shock success rates. The mean first shock energy was 120 +/- 30 joules for patients receiving the current-based method and 200 joules for patients receiving energy-based shocks (p = 0.0001). The mean peak current was 24 +/- 2.3 and 33 +/- 5.0 A, respectively (p = 0.0001). Therefore, for equivalent first shock success rates, the energy-based method delivered 67% more energy and 38% more current than the current-based method. High transthoracic impedance (greater than or equal to 90 omega) predicted first shock failure only in patients undergoing defibrillation by the energy-based method (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗

Comparison of the internal defibrillation thresholds for monophasic and double and single capacitor biphasic waveforms.

Implantable cardiac defibrillators are now an accepted form of therapy for patients with life-threatening ventricular arrhythmias that cannot be controlled by antiarrhythmic drugs. These devices could be made even more acceptable if they were smaller, had increased longevity and the surgical procedure for implantation was less invasive. Reducing the energy requirements for internal defibrillation with use of a nonthoracotomy system would make all of these goals achievable. Monophasic and double and single capacitor biphasic waveforms were compared in 14 anesthetized dogs (25.5 +/- 2.2 kg) with use of a nonthoracotomy lead system that has previously been shown to distribute the delivered voltage throughout the heart more equally. Cathodal catheter electrodes were placed in the right ventricular apex and outflow tract. The anodal electrode was a large cutaneous R2 patch placed over the left side of the chest. The mean energy requirement for defibrillation when a single capacitor biphasic waveform was used was significantly less (6.4 +/- 2.6 J) than that for either the double capacitor biphasic or the monophasic waveform (18.0 +/- 8.0 and 17.4 +/- 8.0 J, respectively) of the same duration. Unexpectedly, the leading edge voltage for the phase I of the single capacitor biphasic waveform was significantly less (266 +/- 51 V) than that for either the double capacitor biphasic or the monophasic waveform (336 +/- 76 and 427 +/- 117 V, respectively). In conclusion, in large dogs, defibrillation is possible at low energy levels with a single capacitor biphasic waveform.

Animals↗

Benefits of implantable defibrillators are overestimated by sudden death rates and better represented by the total arrhythmic death rate.

Benefits of the implantable defibrillator on survival were studied in 56 consecutive patients (concomitant coronary bypass or arrythmia surgery in 15) during an 8 year period between 1982 and 1990. During a follow-up period of 29 +/- 25 months, six patients had a sudden death and eight patients had a nonsudden cardiac death. Nonsudden cardiac deaths included three surgical deaths (death within 30 days after the surgery; two in patients without and one in a patient with concomitant cardiac surgery), one arrhythmia-related nonsudden death (death within 24 h after an arrhythmic event despite initial termination of the arrhythmia by the implantable defibrillators) and four nonarrhythmic cardiac deaths. The actuarial survival rate free of events at 1, 2 and 3 years was 96%, 96% and 92%, respectively, for sudden death, 91%, 91% and 87% for sudden death and surgical mortality and 89%, 89% and 85% for total arrhythmic death (sudden death, surgical mortality and arrhythmia-related nonsudden death). Thus, in patients treated with an implantable defibrillator, 1) the rate of sudden death is low (8% at 3 years); 2) 50% of nonsudden cardiac deaths are causally related to arrhythmia (surgical mortality or arrhythmia-related nonsudden death); 3) the total arrhythmic death rate is substantially higher than the sudden death rate; and 4) benefits of an implantable defibrillator are overestimated by reported sudden death and nonsudden cardiac death rates. The benefits may be better represented by the total arrhythmic death and nonarrhythmic cardiac death rates.

Actuarial Analysis↗

Low-energy defibrillation: safe and effective.

During cardiopulmonary bypass, 150 cardiac surgical patients were prospectively evaluated for the number, energy, current, and success rates of direct current (DC) shocks required to terminate reperfusion ventricular fibrillation (1 degree) or ventricular fibrillation occurring subsequent to a nonfibrillatory reperfusion rhythm (2 degrees). Thirty-one percent of 1-J shocks and 58% of 2.5-J shocks defibrillated. Above 2.5 J, the defibrillation success rate reached a plateau of 50-60%. Myocardial resistance decreased significantly after the first shock but remained stable during subsequent shocks. Lower defibrillating currents and myocardial resistances than had been previously reported were observed. The feasibility of low-energy defibrillation during cardiopulmonary bypass was therefore documented.

Cardiopulmonary Bypass↗

Initial treatment of ventricular fibrillation: defibrillation or drug therapy.

The belief that defibrillation of unwitnessed ventricular fibrillation frequently results in asystole, combined with perceived low survival rates, led to deviation from "standard" advanced cardiac life support (ACLS) by physicians directing paramedics in the field. In nonstandard ACLS, intubation or drug therapy preceded defibrillation. This study retrospectively compared standard and nonstandard ACLS for ventricular fibrillation. The long-term survival rates were 12.3% (7/57) and 3.6% (6/168) for the two forms of ACLS, respectively (p = 0.03). The incidence of postcountershock asystole was 35% and 28% (p = 0.45). The survival rates for patients with a postcountershock rhythm and a pulse were 83% and 17% after standard and nonstandard ACLS (p less than 0.0001). Other factors reported to have a significant effect on survival were compared, and no significant differences (p greater than 0.05) were noted for mean age, sex, cardiopulmonary resuscitation (CPR) initiated by a bystander, ACLS response time, time to CPR, lay-witnessed arrest, or time to definitive care. The significant difference in the time to defibrillation (14 and 26 minutes) was expected. This is the first clinical study to clearly confirm the ACLS recommendation of early defibrillation before drug therapy in ventricular fibrillation.

Aged↗

Report of nitropatch explosions complicating defibrillation.

Reports of complications associated with the use of electrical defibrillators have been relatively rare. In two patients, defibrillation performed over a nitroglycerin skin patch resulted in electrical arcing with a resultant flash of light and thermal injuries. Skin burns as a complication of defibrillation over nitropatches has not been previously reported. Such burn injuries respond to standard therapeutic measures. Healthcare professionals who may perform defibrillation should be aware of this potential complication.

Administration, Cutaneous↗

Systematic evaluation of the determinants of defibrillation efficacy.

OBJECTIVES: We studied the effect of varying shock capacitance, shock impedance, and pulse duration on defibrillation efficacy in a randomized, crossover manner for biphasic shocks. BACKGROUND: The relationship between the electrical determinants of defibrillation efficacy is incompletely understood. METHODS: Biphasic shocks were delivered to 12 dogs through epicardial patches (to vary impedance) after 15 seconds of ventricular fibrillation using one of 100- or 155-muF capacitors at each of four pulse durations (2.5, 5, 10, 20 ms), in a balanced random order. There were two impedance groups: six with higher impedance (mean 97 +/- 15 Omega, range 80-120) and six with lower impedance (mean 39 +/- 3 Omega, range 34-44). Voltage requirements were estimated as the average of three defibrillation threshold (DFT) tests. RESULTS: Shock capacitance, resistance, and pulse duration all had significant effects upon the minimum voltage DFT (P = .0065, P = .0066, and P = .0001, respectively). The tilt associated with the lowest voltage and current requirement for each of the four capacitance/resistance combinations varied widely, between 34 +/- 5% and 63 +/- 3%, depending on capacitance and impedance. The optimal pulse duration associated with minimum DFT lies between 5.11 and 5.34 ms. CONCLUSIONS: Defibrillation voltage requirements for biphasic shocks are affected by pulse duration, capacitance and impedance, but not "tilt."

Animals↗

Long-term subjective memory function in ventricular fibrillation out-of-hospital cardiac arrest survivors resuscitated by early defibrillation.

BACKGROUND: Brain injury after a cardiac arrest remains a major cause of morbidity. Programs focusing on early defibrillation have yielded improved survival of patients after hospital discharge following ventricular fibrillation (VF) out-of-hospital cardiac arrest (OHCA). Early defibrillation that promptly restores a circulating rhythm should decrease the hypoxic period and subsequent organ injury. Therefore this study was designed to determine if long-term memory complaints persist in VF OHCA survivors resuscitated in an early defibrillation program when compared with a healthy control population not experiencing cardiac arrest. METHODS: All patients with an OHCA between November 1990 and January 2001 who received defibrillation by emergency medical services personnel in Olmsted County, MN, USA, were included. The memory function questionnaire (MFQ), a 64-item, 7-point Likert-scaled instrument to evaluate the perception of everyday memory functioning was sent to all survivors. The MFQ comprises four scales: general frequency of forgetting (rates general forgetting), retrospective functioning (compares current memory with past ability), seriousness of forgetting (rates how memory impairment impacts daily life), and mnemonics usage (measures adaptation). The MFQ is scaled so that high scores reflect less severe memory complaints. The comparison population comprised members of the Mayo Older Americans Normative Studies (MOANS) cohort. Quality of life was ascertained with a short form (SF)-36 survey. RESULTS: Seventy-nine of the 200 VF OHCA patients (40%) were discharged. Twenty-two patients have died since dismissal, with an overall average length of follow-up of 4.9+/-3.0 years. Thirty-eight (67%) of the survivors completed the MFQ. Compared with the normal, there was a significant decrease in the general frequency of forgetting score of 144.2+/-37.4 versus 168.1+/-27.3 ( P<0.001) and the seriousness of forgetting score of 84.8 +/-26.7 versus 95.2+/-19.7 (P=0.004). The retrospective function-scale scores were not significantly different ( 18.4+/-6.8 versus 18.7+/- 5.0 (P=0.74). Younger patients (lesser than 65 years of age) reported an increase in general forgetting and the seriousness of forgetting compared with older survivors. A comparison with SF-36 scores suggested an association between general forgetting and decreased vitality (P=0.03) and the seriousness of forgetting with a decreased general health (P=0.005), mental health (P=0.009), physical functioning ( P=0.02 ), and vitality ( P=0.05). CONCLUSION: In a cohort of VF OHCA patients, survivors report more memory complaints in comparison with a general healthy older population. There were more long-term-memory complaints in younger patients. Patients with higher long-term quality-of-life score have fewer memory complaints.

Adult↗

Public access defibrillation--designing a universal report form and database for a national programme.

We describe the design of a universal report form for use by lay-responders using an automated external defibrillator (AED) as part of a national programme for public access defibrillation (PAD). The form was designed initially because the Department of Health in England required detailed audit data about the national programme for public access defibrillation they initiated. At that time (1999) there was very little reported experience of public access defibrillation and none from the UK. The form evolved pragmatically as experience showed the wide range of situations under which lay-persons might use an AED, and also the information likely to be available that could be collected reliably. This report may help others who wish to audit schemes for PAD and facilitate the evolution of an internationally acceptable template for data collection.

Databases, Factual↗

External defibrillation in the left lateral position--a comparison of manual paddles with self-adhesive pads.

INTRODUCTION: Firm paddle force during defibrillation lowers transthoracic impedance (TTI) and increases transmyocardial current, increasing the chances of successful cardioversion. Current protocols recommend that if defibrillation using the anterior-apical (AA) paddle position fails, the anterior-posterior (AP) position should be used. This generally requires the patient to be placed in the left lateral position with the operator leaning over the patient. Avoiding physical contact with the patient during defibrillation subjectively makes application of firm paddle force difficult in the AP position. We compared TTI between the AA and AP positions and between manual paddles and self-adhesive pads to establish if the AP position precludes firm paddle force and to compare TTI between paddles and self-adhesive pads. METHODS: Twenty-one consecutive patients undergoing elective cardioversion (age 39-82) were studied. TTI was measured between pairs of manually held paddles and self-adhesive pads using AA placement with the patient supine, and AP placement with the patient left lateral position. RESULTS: Mean TTI using the AP electrode position was lower using manual paddles (66.5 Omega; 95% CI 60.2-72.9 Omega) than that using self-adhesive pads (92.1 Omega; 95% CI 81.5-102.7 Omega; 95% CI between the mean =15.8-35.5 Omega; P <0.0001). TTI was significantly less using the manual paddles compared with self-adhesive pads in both AA and AP positions (P <0.0001). CONCLUSION: Despite the subjective difficulties of defibrillating patients in the AP position whilst leaning over them, use of manual paddles achieves a lower TTI than that achieved with self-adhesive pads.

Adult↗

Differences in time to defibrillation and intubation between two different ventilation/compression ratios in simulated cardiac arrest.

OBJECTIVE: During basic life support (BLS) by a two-rescuer-team early defibrillation and ALS procedures should be performed without interruptions of the BLS-ventilation/compression sequence. The objective of this study was to determine the impact of a ventilation/compression ratio of 5:50 versus 2:15 on the time intervals "Start BLS to first shock" and "Start BLS to intubation". METHODS: Using a random cross over design 40 experienced paramedics performed a standard BLS/ALS-algorithm according to ILCOR guidelines in a manikin model with ventricular fibrillation (resusci skillreporter anne, Laerdal, Norway) performing both the 2:15 and the 5:50 ventilation/compression ratio. BLS was started with bag/valve/mask ventilation, a semi-automatic defibrillator (corpuls 08/16S) was connected with the manikin, ECG-analysis and three shocks were performed and the tracheal intubation was prepared. Ventilation/compression sequence was only interrupted during ECG-analysis and defibrillation. Expiratory volumes and number of compressions were measured. Variables were compared using paired Students t-test. In addition paramedics were interviewed about work-flow and emotional stress during the tests. RESULTS: The time interval "Start BLS to first shock" was 78 s (2:15-group) versus 63 s (5:50-group), p<0.0001, the time interval "Start BLS to intubation" was 183 s (2:15-group) versus 150 s (5:50-group), p<0.0001, mean ventilation volumes per minute were 4490 ml (2:15-group) versus 4370 ml (5:50-group), p>0.1, mean number of compressions were 65 min-1. (2:15-group) versus 68 min-1 (5:50-group), p>0.1. The work-flow and emotional stress was appraised by the paramedics to be significantly superior in the 5:50 ratio (p<0.0001). CONCLUSIONS: The ventilation/compression ratio of 5:50 compared with 2:15 during BLS with an unsecured airway reduces the time until the first defibrillation and tracheal intubation was performed without changes in ventilation volume and compressions per minute. The Paramedics stated that the 5:50 ratio improved the work-flow and reduced the emotional stress.

Allied Health Personnel↗

Quadriphasic waveforms are superior to triphasic waveforms for transthoracic defibrillation in a cardiac arrest swine model with high impedance.

BACKGROUND: We have demonstrated previously that triphasic waveform shocks were superior to biphasic waveform shocks for transthoracic defibrillation. Our purpose was to compare the efficacy and safety of quadriphasic versus triphasic shocks for transthoracic defibrillation in a porcine model. METHODS: Sixteen adult swine (19-25 kg, mean: 21.5 kg) were deeply anesthetized and intubated. To simulate impedance of the human chest, fixed electrical resistors (25 or 50 ohms) was placed in series with the defibrillator and the chest of each pig. After 30 s of electrically induced VF, each pig received transthoracic shocks, using either a truncated exponential triphasic waveform (5 ms positive pulse duration, 5 ms negative pulse duration and 5 ms positive pulse duration, total waveform duration 15 ms) or a quadriphasic waveform (5/5/5/5 ms, total waveform duration 20 ms). Each pig received transthoracic triphasic and quadriphasic shocks at three selected energy levels (50, 100 and 150 J) in random sequence. Four shocks were delivered at each energy level to construct an energy versus % success curve. Success was defined as VF termination at 5 s after shock. The total shocks were divided into three groups based on the delivered energy actually delivered to the animal: <40, 40-65 and >65 J. Delivered energy = (animal impedance/total impedance) times selected energy of the shock. RESULTS: For high-impedance animals (86-102 ohms), quadriphasic waveform shocks achieved significantly higher percent shock success than triphasic shocks for the termination of VF at the energy levels of >65 J actually delivered (quadriphasic 72.7+/-12.2%, triphasic 38.9+/-7.7%, p<0.02). No differences in the shock success between quadriphasic and triphasic waveforms were found for other two energy levels. There were no differences in ventricular tachycardia or asystole after shocks between quadriphasic and triphasic waveforms. CONCLUSION: In this porcine model, 20 ms (5/5/5/5) quadriphasic shocks were superior to 15 ms (5/5/5) triphasic shocks for transthoracic defibrillation in animals with impedances that simulated high impedance in humans.

Animals↗

Cellular mechanism of reentry induced by a strong electrical stimulus: implications for fibrillation and defibrillation.

The objective of this review article is to describe the graded response hypothesis of reentry induced by a strong single electrical stimulus in the normal canine ventricular myocardium. It is shown that the graded responses (subthreshold depolarization during phase 3 of the action potential) induced at a site distant (S2) from the regular S1--S1 pacing site, propagate slowly over short distances (approximately 5 mm) and initiate a regenerative action potentials in recovered cells near the S1 site. Activation wave then blocks near the S2 site (unidirectional block) but reenters when the S2 site recovers it excitability. Super strong S2 currents do not induce reentry (upper limit of vulnerability). Since similar activation sequence and properties are shown to exist in intact canine hearts during induction of ventricular fibrillation with a similar S2 stimulus, the graded response hypothesis may have relevance to vulnerability to fibrillation. Furthermore, since the upper limit of vulnerability is closely related to defibrillation threshold, the graded response hypothesis might also be relevant to defibrillation mechanism. Other proposed mechanisms of fibrillation and defibrillation (critical point hypothesis, the progressive depolarization hypothesis and the hypothesis of phase singularity of defibrillation failure) are also discussed in this review paper and compared to the graded response hypothesis.

Animals↗

Tedisamil increases coherence during ventricular fibrillation and decreases defibrillation energy requirements.

INTRODUCTION: Drugs which primarily prolong cardiac refractoriness decrease defibrillation voltage and energy requirements in animals and man. The effect of such drugs on ventricular fibrillation itself is not well understood. We hypothesized that tedisamil, an investigational antiarrhythmic drug which blocks Ito and IK repolarizing potassium channels, would increase organization of epicardial electrograms during ventricular fibrillation while it lowered defibrillation energy requirements. METHODS: We measured magnitude-squared coherence, a measure of spatial organization, and ventricular fibrillation (VF) cycle length, ventricular effective refractory period (VERP), and monophasic action potential duration (APD90) as well as defibrillation energy threshold (E50) at baseline and after 150 micrograms/kg of tedisamil (n = 13) or saline control (n = 6) in an open chest dog model. RESULTS: After tedisamil, mean magnitude-squared coherence increased by 132 +/- 133%, from 0.15 +/- 0.08 to 0.31 +/- 0.16 (P < 0.001); VF cycle length increased from 121 +/- 24 to 190 +/- 63 ms (P < 0.001) and became more regular, with the coefficient of variation between adjacent VF intervals decreasing from 14.1 +/- 6.9 to 3.9 +/- 2.2% (P < 0.001). Mean E50 decreased from 8.9 +/- 3.8 to 6.1 +/- 2.7 joules (P < 0.001); VERP increased from 158 +/- 30 to 201 +/- 31 ms (P < 0.001), and APD90 increased from 177 +/- 25 to 244 +/- 45 ms (P < 0.001) after tedisamil. No electrophysiologic parameter was changed after saline infusion. CONCLUSIONS: Tedisamil increases both spatial coherence and temporal regularity of ventricular fibrillation. These effects on 'order' during VF may be in part responsible for the observed reduction in defibrillation energy requirements.

Animals↗

Clinical efficacy of a truncated exponential decay defibrillator.

Trans-chest electrical ventricular defibrillation was attempted in eight adult patients using a 400 watt-second truncated exponential decay waveform defibrillator. All attempts occurred in the immediate post-operative period after heart surgery. Five of the eight subjects were defibrillated (63% success). This success rate is similar to that of 300 watt-second damped sinusoidal waveform defibrillators.

Adult↗

Animated images of cardiac membrane voltage during defibrillation.

Optical recording using voltage-sensitive dyes has been used to investigate the mechanisms of defibrillation because it (1) is immune to the artifacts produced by high-voltage shocks, (2) provides the time course of the membrane action potential, and (3) can be used to make simultaneous recordings at many sites. The authors used the laser scanning technique to optically record action potentials from 100 sites with 1-ms resolution on the surface of the isolated, perfused rabbit heart during defibrillation. The data were typically analyzed by constructing maps of impulse propagation and examining individual recordings from sites of interest. Described here is a new analysis method that creates millisecond-by-millisecond images of the spatial distribution of membrane potentials. The experimental protocol applied a test shock to the fibrillating heart, followed by a rescue shock and a paced beat. Optical recordings were calibrated to yield membrane voltage as a percentage of the resting and overshoot levels of the postrescue stimulated action potential. The positions of the recording sites and the membrane voltage levels for all 100 sites during a single 1-ms interval were used to interpolate membrane voltage levels at points within a 128 x 128 pixel frame using the biharmonic interpolation method. The level of membrane potential was encoded by pixel color and surface elevation. Sequential frames were viewed as a face-on two dimensional or as a three-dimensional perspective of the colored surface. Animation of membrane voltage distributions enabled the visualization of the interaction between the shock-induced electrophysiologic response and the propagation of electrical activity preceding and following a defibrillation shock. Successful defibrillation shocks synchronized repolarization across the surface of the heart following the shock.

Action Potentials↗