Extensive pectoral muscle necrosis after defibrillation: nonthermal skeletal muscle damage caused by electroporation

Isolated Proximal Black Esophagus in a COVID-19 Patient

Black esophagus or acute esophageal necrosis (AEN) is a rare cause of upper gastrointestinal (UGI) bleeding usually involving distal esophagus. Proximal esophageal involvement is quite rare. We present an 86-year-old female with active coronavirus disease 2019 (COVID-19) infection who came in with newly diagnosed atrial fibrillation and was started on anticoagulation. She subsequently developed a UGI bleed, which was complicated by inpatient cardiac arrest. Following resuscitation and stabilization, UGI endoscopy showed circumferential black discoloration of proximal esophagus, with distal esophageal sparing. Conservative management was instituted and fortunately, repeat UGI endoscopy two weeks later showed improvement. This describes the first case of isolated proximal AEN in a COVID-19 patient.

Evidence for Acute Myocardial and Skeletal Muscle Injury after Serial Transthoracic Shocks in Healthy Swine

Background

Previous serological studies have shown controversial results whether defibrillation or cardioversion can cause myocardial injury. Cardiovascular Magnetic Resonance (CMR) can be used to detect myocardial edema, hyperemia and capillary leak as features of acute myocardial injury. The aim of this study was to assess for myocardial and skeletal muscle injury in swine following transthoracic shocks.

Methods

Seventeen anaesthetized swine were examined, with 11 undergoing five synchronized transthoracic shocks (200J). Myocardial and skeletal muscle injury were assessed at baseline and up to 5h post-shock employing T1 mapping, T2 mapping, early and late gadolinium enhancement. Serologic markers (cFABP, TnI, CK, and CK-MB) and myocardial tissue were assessed by standard histology methods.

Results

In myocardial regions within the shock path, T1 and T2 were significantly increased compared to remote myocardium in the same animals. The early gadolinium enhancement ratio between the left-ventricular myocardium and the right pectoral muscle was also increased compared to control animals. After the shocks cFABP and CK were significantly elevated. After shock application, the regions identified as abnormal by CMR showed significantly increased interstitial and myocardial cell areas in histological analysis. This increased cell area suggests significant cellular and interstitial edema.

Conclusion

Our pilot study data indicate that serial defibrillator shocks lead to acute skeletal muscle and myocardial injury. CMR is a useful tool to detect and localize myocardial and skeletal muscle injury early after transthoracic shocks in vivo. In the future the technique could potentially be used as an additional tool for quality control such as verifying insufficient local shock application in non-responders after cardioversion or to develop safer shock forms.

Burn progression secondary to cardioversion

Severe burns result in a profound hypermetabolic response. Catecholaminergic surges secondary to the burn injury itself, particularly if superimposed on premorbid cardiac disease, can result in cardiac arrhythmias. If unstable, these cardiac rhythm disturbances necessitate immediate cardioversion to regain normal sinus rhythm. Because of the high impedance at the skin-paddle interface, superficial cutaneous burns have been known to develop secondary to cardioversion. The authors describe a novel case of the subsequent local progression of a previously sustained superficial flame burn to full-thickness burn injury after cardioversion.

Effects of varying pulse parameters on ion homeostasis, cellular integrity, and force following electroporation of rat muscle in vivo

Electroporation is a technique used in vitro, ex vivo, and in vivo to permeabilize cell membranes. The effect on the tissue describes a continuum ranging from mild perturbations to massive tissue damage. Thus care should be taken when choosing pulses for a given application. Here the effects of electroporation paradigms ranging from severe to very gentle permeabilization were investigated on soleus, mainly composed of slow-twitch fibers, and extensor digitorum longus (EDL) and tibialis anterior (TA), almost exclusively composed of fast-twitch fibers. Five key physiological parameters were studied: force, muscle Na(+), K(+), and Ca(2+) content, and plasma lactate dehydrogenase activity. Four-week-old Wistar rats were anesthetized, and the lower part of the hind leg was electroporated. Blood samples were collected from the tail vein, and at the times indicated animals were killed and TA, EDL, and soleus muscles were collected for analysis of force and ion contents. Muscles were given eight high-voltage pulses of 100-mus duration (8HV) at varying field intensity, one short high-voltage pulse combined with one long low-voltage pulse (HVLV), or eight medium-voltage pulses of 20-ms duration (8MV). Intensity of the electrical field strength was determinant for the degree of changes observed in the muscle. Field strengths below 300 V/cm did not give rise to measurable changes, whereas 8HV pulses at high field intensities (1,200 V/cm) caused severe and long-lasting damage to the muscle. Interestingly, the damage was more pronounced in EDL and TA compared with soleus, possibly because of the difference in fiber type composition. HVLV only caused temporary changes, with force and ion content being normalized by 4 h, suggesting that this pulse combination may be useful for the introduction of ions and molecules (e.g., DNA) into muscle cells.

Activation of transgene expression in skeletal muscle by focused ultrasound

To correlate thermal dose from focused ultrasound (FUS) with gene expression and tissue injury, a temperature plateau strategy was employed. Plasmids encoding luciferase gene under the control of hsp70B promoter were transfected into the right gastrocnemius muscle in a rat via electroporation. One day after transfection, hind limbs were treated with 3.3-MHz focused ultrasound, using one of four different temperature plateaus with spatial-peak time-average focal temperatures (T(SPTA)) of 46 degrees C, 48 degrees C, 51 degrees C and 62 degrees C. The treatment duration at the plateau temperature was varied from 0 to 30s. Gene expression was analyzed in vivo one day following FUS treatment, and H&E staining was employed to assess tissue injury. Gene activation and tissue damage correlated closely with thermal dose. The highest level of gene activation was induced by FUS at T(SPTA)=51 degrees C for 20s, which was found to be statistically equivalent to that produced by water-bath hyperthermia.

Ventricular fibrillation and the use of automated external defibrillators on children

The use of automated external defibrillators (AEDs) has been advocated in recent years as a part of the chain of survival to improve outcomes for adult cardiac arrest victims. When AEDs first entered the market, they were not tested for pediatric usage and rhythm interpretation. In addition, the presumption was that children do not experience ventricular fibrillation, so they would not benefit from use of AEDs. Recent literature has shown that children do experience ventricular fibrillation, and this rhythm has a better outcome than do other cardiac arrest rhythms. At the same time, the arrhythmia software on AEDs has become more extensive and validated for children, and attenuation devices have become available to downregulate the energy delivered by AEDs to allow their use in children. Pediatricians are now being asked whether AED programs should be implemented, and where they are being implemented, pediatricians are being asked to provide guidance on the use of AEDs in children. As AED programs expand, pediatricians must advocate on behalf of children so that their needs are accounted for in these programs. For pediatricians to be able to provide guidance and ensure that children are included in AED programs, it is important for pediatricians to know how AEDs work, be up-to-date on the literature regarding pediatric fibrillation and energy delivery, and understand the role of AEDs as life-saving interventions for children.

Unusual etiology of acute lung injury in a patient with acute myocardial infarction

BACKGROUND

The known etiology of acute lung injury (ALI) is immensely varied and includes severe burns and trauma. Electrical and multiple defibrillation shocks can cause cutaneous burns and blunt chest trauma. The literature contains no reference to the association between ALI and cutaneous burns or blunt chest trauma secondary to defibrillation.

OBJECTIVE

To report a patient with Acute Myocardial Infarction (AMI) who developed ALI possibly due to multiple defibrillation shocks.

CASE REPORT

A 51 year-old man with AMI presenting with multiple episodes of ventricular fibrillation (VF) treated with defibrillation and subsequently cutaneous burns. He developed soon afterward respiratory failure due to ALI. Cardiac failure or any known etiology of ALI was ruled out. Medical treatment included oxygen therapy, cardiac frequency control with betablockers, in addition to antiplatelet therapy. Clinical and oxymetric evolution was favourable, with resolution of the radiological infiltrates. The patient was discharged alive and in good condition at the 19th day after admission. The authors discuss possible mechanisms of ALI development by multiple defibrillation shocks.

CONCLUSIONS

In the absence of any other known etiology, multiple defibrillation shocks may have played a role in the genesis of ALI in our patient, but this remains speculative.

A randomised controlled trial of the effect of biphasic or monophasic waveform on the incidence and severity of cutaneous burns following external direct current cardioversion

OBJECTIVE

Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion. We designed a prospective randomised double-blinded controlled study to determine the effect of biphasic or monophasic waveform on the pain and inflammation occurring after elective cardioversion.

MATERIALS AND METHODS

One hundred and thirty nine patients undergoing elective DC cardioversion were randomised to receive monophasic (HP Codemaster XL; 100, 200, 300, 360, and 360 J) or biphasic (Welch Allyn-MRL PIC defibrillator; 70, 100, 150, 200, and 300 J) waveforms. Two hours after DC cardioversion, skin temperature, erythema index and sensory threshold to light and sharp touch was measured at the centre and edge of paddle sites. Visual analogue pain score (VAS) was recorded at 2 and 24 h.

RESULTS

There was significantly less pain following biphasic cardioversion as assessed by VAS at both 2 h (p < 0.001; 95% confidence intervals of difference of medians (CI) 0.2-0.8 cm) and 24 h (p = 0.004; 95% CI 0.0-0.4 cm). There was significantly less erythema in patients receiving biphasic cardioversion at the edge of the sternal site (p = 0.046; 95% CI 0.41-4.5). There was no difference in any other variable at any site between biphasic and monophasic cardioversion.

CONCLUSION

The use of a biphasic waveform for DC cardioversion reduces the inflammation and pain of burns as measured by erythema index and visual analogue scale.

The effect of prophylactic topical steroid cream on the incidence and severity of cutaneous burns following external DC cardioversion

INTRODUCTION

Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion. We designed a prospective double-blinded controlled study to determine whether the application of steroid cream prior to cardioversion reduces their incidence and severity.

MATERIALS AND METHODS

Two hours before elective DC cardioversion, we applied betamethasone 0.1% cream or placebo cream over sternal and apical pad sites in 56 patients, with patients acting as their own controls. Two hours after cardioversion, a separate blinded observer measured the visual analogue pain score (VAS), sensory and pain detection thresholds, skin temperature and erythema index at sternal and apical pad sites.

RESULTS

The study had an 80% power to detect a 50% difference in VAS at 2 h, accepting an alpha error of 0.05. There was no difference between pain at 2 or 24 h, skin temperature, erythema index, sensory and pain detection thresholds at pad sites treated with steroid cream or control.

CONCLUSION

Topical betamethasone 0.1% cream applied 2 h before elective DC cardioversion is no more effective than placebo at reducing the pain and inflammation from cardioversion burns.

The effect of topical non-steroidal anti-inflammatory cream on the incidence and severity of cutaneous burns following external DC cardioversion

INTRODUCTION

Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion. We designed a study to determine whether the application of non-steroidal anti-inflammatory cream prior to cardioversion reduces their incidence and severity.

MATERIALS AND METHODS

Two hours before elective DC cardioversion, we randomised 55 patients to receive ibuprofen 5% cream or placebo cream over sternal and apical pad sites, with patients acting as their own controls. Two hours after cardioversion an independent blinded observer measured skin temperature, erythema index, and minimum sensory and pain detection thresholds at sternal and apical pad sites. Visual analogue pain score (VAS) for each site was recorded at 2 h and 24 h post-cardioversion.

RESULTS

There was a statistically significant difference between pain measured by VAS, skin temperature and pain detection threshold measured at pad sites with pre-applied ibuprofen 5% cream and those with pre-applied aqueous cream, after elective DC cardioversion.

CONCLUSION

Prophylactic application of topical ibuprofen 5% cream 2h prior to elective DC cardioversion reduces pain and inflammation. Consideration should be given to use of prophylactic application of topical ibuprofen as routine treatment for elective DC cardioversion.

The incidence and severity of cutaneous burns following external DC cardioversion

INTRODUCTION

Cutaneous burns are a common cause of morbidity following direct current (DC) cardioversion, but the incidence and severity have never been quantified.

MATERIALS AND METHODS

Two hours after elective DC cardioversion in 83 sequential patients, we measured skin temperature, erythema index, and minimum sensory and pain detection thresholds at paddle sites and control sites on the contralateral side. Visual analogue pain score (VAS) was recorded at 2 and 24h post-cardioversion.

RESULTS

Values for areas over paddle sites were higher (P < 0.05) than control site for all variables measured at 2h. Eighty-four percent patients experienced some pain and 23% patients experienced moderate to severe pain as assessed by VAS. Burns were greater at the edge than the centre of sternal sites and greater at sternal than apical sites. There were positive correlations between transthoracic impedance (TTI) and total energy delivered (r(2) = 0.048; P = 0.04); total energy and pain at 2 h (r(2) = 0.38; P < 0.0001) and 24 h (r(2) = 0.23; P < 0.0001); and number of shocks and pain at 2 h (r(2) = 0.36; P < 0.0001) and 24 h (r(2) = 0.19; P < 0.0001).

CONCLUSION

Elective DC cardioversion causes burns as measured by skin temperature, erythema index and sensory threshold to sharp touch. Pain experienced is related to the total energy and number of shocks delivered. To reduce burns, operators should apply optimal paddle force equally to both paddles, with the paddles applied so as to provide even contact along their edges. Burns may also be minimised by starting with lower energy shocks.

Dynamic nature of electrocardiographic waveform predicts rescue shock outcome in porcine ventricular fibrillation

STUDY OBJECTIVE

Survival decreases with duration of ventricular fibrillation, and it is possible that failed rescue shocks increase myocardial damage. Structure in the ECG signal during ventricular fibrillation can be quantified by using the scaling exponent, a dimensionless measure that correlates with ventricular fibrillation duration. This study examined whether the scaling exponent could predict rescue shock success and whether unsuccessful rescue shocks altered the structure of the ventricular fibrillation waveform and the responsiveness to subsequent rescue shocks.

METHODS

Ventricular fibrillation was electrically induced in 44 anesthetized swine, which were randomly assigned to receive 70-J biphasic rescue shocks at 2, 4, 6, 8, or 10 minutes. If rescue shocks failed, up to 2 subsequent rescue shocks were performed at 2-minute intervals. The scaling exponent was calculated at 1-second intervals from ECG to quantify the organization of the ventricular fibrillation waveform.

RESULTS

A total of 92 rescue shocks were delivered, of which 23 successfully converted ventricular fibrillation to an organized rhythm (immediate success). After these 23 rescue shocks, 14 swine sustained organized rhythms for more than 30 seconds (sustained success). Lower scaling exponent values were associated with increased probability of successful rescue shocks. Receiver operating characteristic curves had an area under the curve of 0.86 for immediate rescue shock success and 0.93 for sustained rescue shock success. Failed rescue shocks increased the rate of scaling exponent increase over time but did not appear to affect subsequent rescue shock success when the scaling exponent was taken into account.

CONCLUSION

Highly deterministic ventricular fibrillation, reflected by a low scaling exponent, predicted rescue shock success regardless of antecedent failed rescue shocks. In addition, unsuccessful rescue shocks might decrease post-rescue shock ventricular fibrillation waveform organization.

Estimation of current density distribution under electrodes for external defibrillation

BACKGROUND

Transthoracic defibrillation is the most common life-saving technique for the restoration of the heart rhythm of cardiac arrest victims. The procedure requires adequate application of large electrodes on the patient chest, to ensure low-resistance electrical contact. The current density distribution under the electrodes is non-uniform, leading to muscle contraction and pain, or risks of burning. The recent introduction of automatic external defibrillators and even wearable defibrillators, presents new demanding requirements for the structure of electrodes.

METHOD AND RESULTS

Using the pseudo-elliptic differential equation of Laplace type with appropriate boundary conditions and applying finite element method modeling, electrodes of various shapes and structure were studied. The non-uniformity of the current density distribution was shown to be moderately improved by adding a low resistivity layer between the metal and tissue and by a ring around the electrode perimeter. The inclusion of openings in long-term wearable electrodes additionally disturbs the current density profile. However, a number of small-size perforations may result in acceptable current density distribution.

CONCLUSION

The current density distribution non-uniformity of circular electrodes is about 30% less than that of square-shaped electrodes. The use of an interface layer of intermediate resistivity, comparable to that of the underlying tissues, and a high-resistivity perimeter ring, can further improve the distribution. The inclusion of skin aeration openings disturbs the current paths, but an appropriate selection of number and size provides a reasonable compromise.

Electrical injuries

Electrical injury is a relatively infrequent but potentially devastating form of multisystem injury with high morbidity and mortality. Most electrical injuries in adults occur in the work-place, whereas children are exposed primarily at home. In nature, electrical injury occurs due to lightning, which also carries the highest mortality. The severity of the injury depends on the intensity of the electrical current (determined by the voltage of the source and the resistance of the victim), the pathway it follows through the victim's body, and the duration of the contact with the source of the current. Immediate death may occur either from current-induced ventricular fibrillation or asystole or from respiratory arrest secondary to paralysis of the central respiratory control system or due to paralysis of the respiratory muscles. Presence of severe burns (common in high-voltage electrical injury), myocardial necrosis, the level of central nervous system injury, and the secondary multiple system organ failure determine the subsequent morbidity and long-term prognosis. There is no specific therapy for electrical injury, and the management is symptomatic. Although advances in the intensive care unit, and especially in burn care, have improved the outcome, prevention remains the best way to minimize the prevalence and severity of electrical injury.

Optimization of the defibrillation current density in the heart region by a two-layer segmented electrode

Transthoracic defibrillation is a procedure applying high intensity electrical current through the thorax region by electrodes, in order to simultaneously activate most of the myocardial cells, thus enforcing them to reinstate a normal rhythm. A solution is proposed for analysis and synthesis of the current density distribution field in the heart region. In an attempt to reach uniform excitation of the greatest possible quantity of myocardial cells, a field image is searched for, with the J-vector uniformity distribution as a criterion. The finite element method and the method of approximating functions are used, as well as nonlinear programming. This approach resulted in designing a two-layer defibrillation electrode, with the layer applied to to the thorax divided in three different resistivity regions.