Electromechanical dissociation

Parenfera/- The most important treatment-emergent adverse effects were hypotension, asystole/cardiac arrest/electromechanical dissociation (EMD), cardiogenic shock, CFIF, bradycardia, liver function test abnormalities, VT, and AV block. The most common adverse effects leading to discontinuation of IV therapy were hypotension, asystole/cardiac arrest/EMD, VT, and cardiogenic shock. Adverse reactions occurring in at least 3% of patients include nausea. 

When the cardiac electrical activity is maintained, but there is no mechanical output (pulseless electrical activity, electromechanical dissociation), then hypovolaemia, tension pneumothorax, pulmonary embolism, cardiac tamponade, and various forms of metabolic or pharmacological disturbance may be responsible. In asystole or pulseless electrical activity (with an underlying rate of less than 60 beats per minute) a single intravenous bolus of 3 mg atropine is recommended. 

The patients who have the best chance of surviving cardiac arrest are those with primary ventricular flbrillation after myocardial infarction patients with electromechanical dissociation or asystole fare worst. Even in those in the most favourable group, with witnessed ventricular fibrillation in hospital, the best that can be hoped for is a survival rate till discharge of about 20%. 

It has been suggested that bupivacaine may be more cardiotoxic than other long-acting local anesthetics (eg, ropivacaine). This reflects the fact that bupivacaine-induced blockade of sodium channels is potentiated by the long action potential duration of cardiac cells compared with nerve fibers. The most common electrocardiographic finding in patients with bupivacaine intoxication is a slow idioventricular rhythm with broad QRS complexes and eventually electromechanical dissociation. 

In acute MI, the ISIS-1 study [88] was organized to assess the effects of early beta-blockade with atenolol on cardiovascular mortality during the first week following infarction and after long-term (mean 20 months) follow-up. There was a 15% reduction in vascular deaths, especially in the early phase of MI. The difference in early mortality was mainly due to a reduction in electromechanical dissociation in the presence of atenolol. In this regard, atenolol is usually given by intravenous injection or infusion to treat cardiac arrhythmias, and it should be noted that atenolol induced atrial fibrillation in half of the so-predisposed patients [89]. 

Free-wall rupture is the most frequent and may be acute, followed by sudden death secondary to electromechanical dissociation, or subacute with recurrent chest pain and haemorrhage within the pericardial sac, with or without cardiac tampon-... 

Figure 8.34 Patient of 68 years of age who suffered sudden death 10 days after an acute infarction. A progressive depression of the automatism (with the appearance of a slow escape rhythm) is shown in the Holter ECG recording, until cardiac arrest occurs, due to an electromechanical dissociation caused by cardiac rupture.

Lindner KH, Ahnefeld FW, Prengel AW. Comparison of standard and high-dose adrenaline in the resuscitation of asystole and electromechanical dissociation. Acta Anaesthesiol Scand 1991 35 253-256. 

Waxman AB, White KP, Trawick DR. Electromechanical dissociation following verapamil and propranolol ingestion a physiologic profile. Cardiology (1997) 88, 478-81. 

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