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Cardiac surgery
Published in Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie, Bailey & Love's Short Practice of Surgery, 2018
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie
A precordial thump may be performed if within 10 s of the onset of VF or pulseless VT; however, this should not delay cardioversion by defibrillation. In VF or pulseless VT, emergency resternotomy should be performed after three failed attempts at defibrillation.
Resuscitation
Published in Karim Ratib, Gurbir Bhatia, Neal Uren, James Nolan, Emergency Cardiology, 2010
Karim Ratib, Gurbir Bhatia, Neal Uren, James Nolan
The only definitive treatment for VF or pulseless VT is defibrillation. Although these rhythms are initially readily treatable, the chances of successful defibrillation diminish rapidly with time and decline by 7–10 per cent per minute. In the case of a witnessed arrest especially when a shockable rhythm has been identified, it is reasonable to attempt a precordial thump. The thump delivers a small amount of kinetic energy, which may be adequate to convert a fibrillating myocardium. All reported cases of successful precordial thump occurred within 10 seconds of VF/VT. If precordial thump is not successful or if VF/VT is more prolonged then electrical cardioversion is required. Often, patients are not monitored and the duration of VF/VT is unknown, in this case chest compressions should be initiated first until the rhythm is determined. Experimental studies have shown that interruption in chest compressions is associated with a lower chance of survival. In addition, interruptions in chest compression reduce the chance of successfully converting VF to another rhythm. Therefore, unless the patient is monitored and defibrillation can be achieved immediately after collapse, chest compressions should be started and maintained until defibrillation is possible. Following defibrillation chest compressions should be continued as delay in checking for a pulse may further compromise the myocardium if a perfusing rhythm has not been restored.
The Decomposed Body and the Unascertained Autopsy
Published in Julian L Burton, Guy Rutty, The Hospital Autopsy, 2010
Sudden application of blunt force trauma to the anterior chest wall at the correct point in the cardiac cycle can trigger a fatal ventricular fibrillation cardiac arrest. This is analogous to the administration of a precordial thump to a patient in cardiac arrest, in which the mechanical energy is converted into the equivalent of an approximately 20 J shock which affects the cardiac rhythm. This is known as ‘commotio cordis’ (Maron et al., 2002). Animal experimentation has shown that a blow to the chest wall precisely within 10–30 milliseconds before the peak of the T wave consistently results in ventricular fibrillation (Madias et al., 2007). The diagnosis is made on the basis of a history of immediate collapse following a blow to the chest by a non-collapsible projectile, for example a cricket ball, baseball or hockey puck. The autopsy reveals no positive findings, and detailed cardiac examination, neuropathology, histology, microbiology and toxicological investigations are negative.
Computational modelling of mechano-electric feedback and its arrhythmogenic effects in human ventricular models
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Yongjae Lee, Barış Cansız, Michael Kaliske
After a single healthy heart beat with a regular ECG and a normal LV output (EF t = 1148 ms for 70 ms, where the ventricles are vulnerable to arrhythmia. Accordingly, the regular rhythm of ECG is disturbed along with the transient decrease of LV volume as the region deforms due to the impact, as shown in the snapshot taken at t = 1158 ms in Figure 6. The mechanism behind the regional excitation is that the stretch Figure 7(a) presents the normalized transmembrane potential v-t curve in Figure 6. These abnormalities clinically serve as a critical sign that the heart is not able to pump blood throughout the body. In this case, precordial thump can be a readily available intervention, particularly outside the hospital environment as a method for resetting the heart rhythm (Kohl et al. 1999), which means a mechanical stimulation on the chest has potential to reinstate normal heart beat. We simulate this phenomenon by an application of a moderate force to the biventricular model to terminate the fibrillation. To do so, we first identify the route of the wave propagation on the biventricle model without applying a force. The snapshots in the first row of Figure 7(b) are obtained from the simulation where the precordial thump is not applied, by which we can recognize the path of the propagation. Then, with the propagation course in hand, we apply a blunt blow that hinders the depolarization wave propagation at time t = 6470 ms for 40 ms and the deformed shape is shown in the snapshot taken at t = 6486 ms in Figure 6. The second row of Figure 7(b) shows that the impact is applied to the area to where the propagation wave is reaching, and the area is electrically in the resting state (t = 7200 ms, the AV node is electrically stimulated as scheduled, and the biventricular model starts to contract again, producing the regular ECG and the v-t curve as shown in Figure 6.