Asystole

Absence of any ventricular or atrial activity (Fig. 6.36). There is no cardiac output in this rhythm and unless reversible causes are present the outlook is extremely poor. Sometimes P waves may be present (termed P wave asystole), these patients may be suitable for pacing. It is also important to check the gain on the monitor as fine VF can sometimes be missed as it can look like asystole if not set properly (1 mV per cm). A complete flat line on a monitor is an indication that one of the monitoring leads is not connected properly. 

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The amide local anaesthetic lidocaine may also be used as an antianhythmic for ventricular tachycardia and exra-systoles after injection into the blood circulation. Drugs with high lipid solubility such as bupivacaine cannot be used for these purposes because their prolonged binding to the channel may induce dysrhythmias or asystolic heart failure [3]. Systemically applied lidocaine has also been used successfully in some cases of neuropathic pain syndromes [4]. Here, electrical activity in the peripheral nervous system is reduced by used-dependent but incomplete sodium channel blockade. 

Locatelli ER, Varghese JP, Shuaih A, Potohcchio SJ. Cardiac asystole and bradycardia as a manifestation of left temporal lobe complex partial seizure. Ann Intern Med... 

Rocamora R, Kurthen M, Lickfett L, Von Oertzen J, Eiger CE. Cardiac asystole in epilepsy clinical and neurophysiologic features. Epilepsia 2003 44(2) 179-185. 

Causes of obstructive shock should be entertained in patients with PEA/asystole with absent or low levels of ETC02 after placement of invasive airway. 

Approximately 400,000 people die of sudden cardiac death annually in the United States. While some of these deaths occur as a result of asystole, the majority occur as a result of primary VF or VT that degenerates into VF. Etiologies of VF are presented in Table 6-10 and are similar to those of VT. 

The absence of a pulse does not guarantee VF, as the pulse may also be absent in patients with asystole, VT, or pulseless electrical activity. 

For acute symptomatic hypocalcemia, 200 to 300 mg of elemental calcium is administered IV and repeated until symptoms are fully controlled. This is achieved by infusing 1 g of calcium chloride or 2 to 3 grams of calcium at a rate no faster than 30 to 60 mg of elemental calcium per minute. More rapid administration is associated with hypotension, bradycardia, or cardiac asystole. Total calcium concentration is commonly monitored in critically ill patients. Under normal circumstances, about half of calcium is loosely bound to serum proteins while the other half is free. Total calcium concentration measures bound and free calcium. Ionized calcium measures free calcium only. Under usual circumstances, a normal calcium level implies a normal free ionized calcium level. Ionized calcium should be obtained in patients with comorbid conditions that would lead to inconsistency between total calcium and free serum calcium (abnormal albumin, protein, or immunoglobulin concentrations). For chronic asymptomatic hypocalcemia, oral calcium supplements are given at doses of 2 to 4 g/day of elemental calcium. Many patients with calcium deficiency have concurrent vitamin D deficiency that must also be corrected in order to restore calcium homeostasis.2,37,38... 

Atropine 1 mg IV/IO eveiy 3-5 minutes (maximum total of 3 doses or 3 mg) can be considered for patients with asystole or PEA. 

Once ACLS providers arrive, further definitive therapy is given (Fig. 7-1). If the rhythm is not shockable, it is likely to be either asystole or PEA. 

SuccessM treatment of PEA and asystole depends almost entirely on diagnosis of the underlying cause. Potentially reversible causes include (1) hypovolemia, (2) hypoxia, (3) preexisting acidosis, (4) hyperkalemia, (5) hypothermia, (6) hypoglycemia, (7) drug overdose, (8) cardiac tamponade, (9) tension pneumothorax, (10) coronary thrombosis, (11) pulmonary thrombosis, and (12) trauma. 

Treatment of PEA is similar to treatment of asystole. Both conditions require CPR, airway control, and IV access. DefibriUation should be avoided in asystole because the resulting parasympathetic discharge can reduce the chance of ROSC and worsen the chance of survival. If available, transcutaneous pacing can be attempted. 

Vasopressin can be substituted for the first or second dose of epinephrine in patients with asystole. There is insufficient evidence to make a treatment recommendation for PEA. 

The sequence of cardiovascular signs as serum magnesium increases from 3 mEq/L to 15 mEq/L is hypotension, cutaneous vasodilation, QT-interval prolongation, bradycardia, primary heart block, nodal rhythms, bundle branch block, QRS- and then PR-interval prolongation, complete heart block, and asystole. 

Wolff and co-workers25 found this enzyme activity in plasma to vary over a 3-fold range in an unspecified number of normal cases. From 0.5 to 1.5 pg. of folic acid per ml. of plasma was liberated under specified conditions in 90 minutes. In asystolic patients the corresponding values were from 0.2 to 0.7 pg. 

Nanji AA, Filipenko JD. (1984). Asystole and ventricular fibrillation associated with cocaine intoxication. Chest. 85(1) 132-33. 

Cardiovascular Effects. One of the patients described by Letz et al. (1984) (see Section 2.2.3.1) who had a terminal cardiopulmonary arrest had acute myocardial interstitial edema, myocardial inflammation, and Gram-positive sporulating rods at necropsy. The second patient initially had a normal electrocardiogram, but as his renal and hepatic function deteriorated, eventually developed supraventricular tachycardia and asystole. 

Use quinidine with extreme caution in incomplete AV block, because complete block and asystole may result. The drug may cause unpredictable dysrhythmias in digitalized patients. Use cautiously in patients with partial bundle branch block, severe CHF, and hypotensive states due to the depressant effects of quinidine on myocardial contractility and arterial pressure. 

Digitalis intoxication Exercise caution in the use of procainamide in arrhythmias associated with digitalis intoxication. Procainamide can suppress digitalis-induced arrhythmias however, if there is concomitant marked disturbance of AV conduction, additional depression of conduction and ventricular asystole or fibrillation may result. Consider use of procainamide only if discontinuation of digitalis, and therapy with potassium, lidocaine, or phenytoin are ineffective. 

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. 

Cardiac conduction IV verapamil slows AV nodal conduction and SA nodes it rarely produces second- or third-degree AV block, bradycardia, and in extreme cases, asystole. This is more likely to occur in patients with sick sinus syndrome. 

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