Noninvasive transcutaneous pacing was performed for 30 minutes in 10 healthy volunteers. The pace rate was from 85 to 115 min-1, and the threshold for pacing was from 38 to 70 mA, median 59 mA. Echocardiography before and during pacing showed no changes in left ventricular end-diastolic diameter, in fractional shortening nor in contraction pattern. Also, blood pressure remained unchanged. Blood samples for determination of myoglobin, creatine phosphokinase, creatine kinase MB and lactate dehydrogenase were drawn prior to pacing and 1,2,3,4,6,8 and 24 hours after pacing. The serum concentrations were the same before and after pacing for all enzymes and myoglobin. We conclude that non-invasive transcutaneous pacing for 30 minutes causes no muscular or myocardial injury and that the left ventricular function remains normal.

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Among I70 patients with Adams-Stokes syndrome, the majority had sinus rhythm between attacks. Clinical and electrocardiographic features of 67 patients in whom syncope was caused by paroxysmal third-degree atrioventricular block are discussed. The patients had normal pulse rates between attacks, their cerebral symptoms were usually not accompanied by cardiac symptoms, and 25 per cent had no symptoms suggesting heart disease. However, in 83 per cent the electrocardiogram showed constantly interventricular conduction disturbances and 7I per cent episodically atrioventricular conduction disturbances. It appears that the diagnosis, which otherwise may be missed, may be greatly facilitated by electrocardiograms.The variability and complexity of the QRS patterns suggest a development of third-degree AV block in the form of an 'additive' block. The final lesion in the complete block may vary both in location, proximall distal, in the conduction system, and in degree of involvement of the pacemaking tissue. Both factors may contribute to an alternation between episodes of third-degree AV block with and without escape rhythm, and correspondingly without and with Adams-Stokes attacks.Implantation of an artificial pacemaker is life saving and allows most of the patients who have suffered attacks of unconsciousness, due to episodes of ventricular asystole, to return to normal life (Harris et al., I965; Cosby and Bilitch, I972). This therapeutic achievement has made the identification of patients with Adams-Stokes attacks a matter of practical clinical importance. The diagnosis is straightforward if the fainting spells occur in connexion with chronic third-degree AV block, i.e. in patients with slow heart rate as first described by Adams (I827) and Stokes (I846). However, Adams-Stokes attacks may also occur in patients with sinus rhythm and a correspondingly normal heart rate. The attacks may in these cases be caused by paroxysmal ventricular fibrillation (Harris et al., I965; Sand0e and Flensted-Jensen, I969; Wennevold and Sand0e, 1970), sinoatrial block (Miiller and Finkelstein, i966), or paroxysmal third-degree AV block complicated by ventricular asystole (Stokes, I947).The aim of this paper is to evaluate the prevalence of the latter type of cardiac syncope, to work out criteria for its proper identification, and to elucidate its aetiology and nature. Patients By I972 a total of 170 patients with Adams-Stokes attacks had had a pacemaker implanted at the University Hospital of Copenhagen. One hundred and six patients were in sinus rhythm at the time of the implantation of pacemaker, while 64 had third-degree AV block. The cause of syncope in io6 patients with sinus rhythm was sinoatrial block in 39, and intermittent AV block complicated by ventricular asystole in 67.The latter 67 patients form the basis of the present study. In 62 patients, electrocardiograms during fainting spells showed third-degree AV block and ventricular asystole which lasted for 5 to 6o seconds. In the remaining 5 patients an electrocardiogram was no...

A 76-year-old man had his implanted demand pacemaker inhibited by an electrical leakage current caused by defective grounding in an electrocardiographic recorder power cable. Various measures can be undertaken in order to minimize this hazard, and these are discussed.