Augmentation of cardiac output by external cardiac pacing: pacemaker-induced CPR

A comparison of transoesophageal cardiac pacing and epinephrine for cardiopulmonary resuscitation

The use of cardiac pacing to deal with bradycardia is well established. There is debate as to the benefits during cardiopulmonary resuscitation (CPR). This study was performed to compare the effects of transoesophageal cardiac pacing and high-dose epinephrine on the benefits of cardiopulmonary resuscitation after asphyxial cardiac arrest in rats. Thirty Sprague-Dawley rats of both sexes were randomly selected to a saline group (Sal-gro, treated with normal saline 1 mL IV, n = 10), an epinephrine group (Epi-gro, treated with epinephrine 0.4 mg/kg IV, n = 10), or a pacing group (Pac-gro, treated with normal saline 1 mL IV combined with transoesophageal cardiac pacing, n = 10) in a blinded fashion during resuscitation after 10 minutes of asphyxial cardiac arrest. Manual chest compression was in all cases performed using the same methodology by the same personnel who was blinded to hemodynamic monitor tracings. The rate of restoration of spontaneous circulation was 1 (10%), 7 (70%), and 8 (80%) of 10 in Sal-gro, Epi-gro, and Pac-gro, respectively. The rate of ventilator withdrawal within 60 minutes after resuscitation in Pac-gro was higher than that of Epi-gro (8/8 vs 1/7, respectively; P = .001); the survival rate after 2 hours in Pac-gro was significantly higher than that in Epi-gro (7/8 vs 1/7, respectively; P = .01). The data demonstrate that both epinephrine and transoesophageal cardiac pacing are effective within 10 minutes of asphyxia in rats. It is worth noting that transoesophageal cardiac pacing produced a better outcome with respiration and longer survival time compared with epinephrine after restoration of spontaneous circulation.

Temporary Cardiac Pacing in the Intensive Care Unit

Indications for temporary cardiac pacing have increased substantially in the last several years. Although most temporary cardiac pacing is still carried out to treat symptomatic bradycardia due to atrioventricular conduction system disease or atrial bradycardia (i.e., sinus node dysfunction), temporary pacing is currently used to induce and to terminate some supraventricular tachyarrhythmias, prevent pause-dependent ventricular tachycardia (usually torsades de pointes), and vagally mediated atrial fibrillation, to allow the maintenance of hemodynamic competence in postoperative cardiac patients and to evaluate selected patients with hypertrophic and dilated cardiomyopathies who might benefit hemodynamically from cardiac pacing. The roles of transcutaneous and esophageal pacing have also expanded; transcutaneous pacing is now commonly used in patients at high risk for the development of atrioventricular block, such as those with acute myocardial infarction and bifascicular block. We review available types of temporary pacing leads and pulse generators, the methods by which temporary pacing is accomplished, complications of pacing system insertion, and current indications for this therapy. Guidelines for troubleshooting normal and abnormal pacemaker function in the intensive care unit setting are provided.

Noninvasive transcutaneous cardiac pacing: modern instrumentation and new perspectives

Noninvasive transcutaneous cardiac pacing has evolved from a simple stand alone unit with no ventricular sensing to a complete cardiac arrest resuscitation system combining synchronous pacing and defibrillation capabilities and using a single set of multifunction electrodes. In current instrumentation, four configurations exist including stand alone unit, modular configuration, built-in monitor and recorder, and built-in monitor, recorder and defibrillator. In present day devices, ventricular sensing, extensive programmability, and large surface electrodes are general features. Capture monitoring requires specific integrated electrocardiographic capability. Future developments are expected to involve low threshold electrode technology, integrated mechanical monitoring, and interdevice electrode compatibility.

Left ventricular pressure measurement during noninvasive transcutaneous cardiac pacing

In a pacemaker-dependent patient, the hemodynamic response during external transcutaneous and endocardial sequential pacing was evaluated by left ventricular pressure monitoring. A single ventricular pacing mode with hemodynamic effect of atrioventricular asynchrony was shown during external pacing.

Transcutaneous pacing for cardiac emergencies

Transcutaneous cardiac pacing using the Pace-Aid (Cardiac Resuscitator Corporation) was assessed in 32 emergency patients presenting with profound bradycardia or asystole who had failed to recover with advanced life support including the use of epinephrine. Pacing stimuli, pulse width 20 ms at 50, 100, or 200 mA, were delivered through two 8 cm gel-pad electrodes placed antero-posteriorly on the chest. By ECG criteria, definite electrical capture was achieved in a total of five patients and possible capture in a further 16. Of the 21 patients presenting in asystole 11 showed possible electrical capture only. No evidence of capture was seen in one third of the patients studied. Use of the Pace-Aid resulted in a palpable pulse in a total of seven patients. Four of the 11 patients with profound bradycardia survived to receive temporary transvenous pacing; two were eventually discharged. None in the asystolic group survived. Difficulties in using the Pace-Aid resulted from electrical overload by the pacing impulse that obscured the evidence for electrical capture, and intense muscle contraction that hindered reliable palpation of the arterial pulse. Transcutaneous pacing can occasionally be of value even at a late stage in the emergency treatment of profound bradycardia but is unlikely to be worthwhile in complete asystole.