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During the last decade implantation of permanent pacemakers has become the treatment of choice for patients suffering from the sick sinus syndrome (SSS). We have followed up 112 SSS patients treated with permanent pacemakers in Haukeland Hospital in the period 1966--76. The pacemakers were later removed from three of the patients. In the remaining 109 patients the SSS was characterized by tachy-bradyarrhythmias (TBA) in 44 and bradyarrhythmias (BA) in 65. Before implantation, 68 patients had syncopes and 27 severe dizziness. After implantation, symptomatic improvement was apparent in 104 patients; only three still had syncopes. During the follow-up period (mean 34.4 months), 29 patients died (yearly mortality 9.3%). There was no significant difference in total mortality between patients with TBA and with BA. Concomitant disturbances in atrioventricular (AV) conduction occurred in 35.8% of the patients. Among 79 of 80 patients still alive, five had developed total AV block, 19 had stable atrial fibrillation, 12 of these were possibly pacemaker-independent (ventricular rate greater than 60/min). Systemic embolization was observed in 16 patients, more frequently in the TBA (12/44) than in the BA group (4/65) (p less than 0.001). It is concluded that permanent pacemakers have an excellent symptomatic effect in patients with SSS. The prognosis is mainly determined by the presence or absence of coronary heart disease and/or heart failure.

One-hundred and eighty-one patients with chronic and with intermittent high-grade atrioventricular block (AVB) were studied retrospectively. Seventy-one were treated with fixed-rate, 51 with demand-type pacemaker, 59 were treated conservatively. Observation time was three years minimum and 14.5 years maximum. The mean age was about seven years higher, and 8.7% more patients had chronic AVB in the conservatively treated than in the pacemaker-treated group. About 12% more patients had Adams-Stokes attacks in the pacemaker group than in the conservatively treated group. There were 7% more patients with coronary heart disease (CHD) in the pacemaker group, and 10% more with aortic valve disease among the conservatively treated. Totally 4.4% of the patients had a calcification of the mitral annulus fibrosus. The two groups were comparable as regards functional class (NYHA) and heart size. Survival showed 31% more sudden deaths in the conservatively treated than in the pacemaker group. Sudden deaths were not more frequent among the patients with CHD than in those without. Long-term survival showed the more favourable result for the patients with than without pacemaker treatment. There were eight (11.3%) unexplained sudden deaths among the patients treated with fixed-rate pacemaker, only three (5.9%) among those treated with a demand unit. The fixed-rate and the demand units showed a mean longevity of 37.2 and 34.6 months, respectively.

Patients with myasthenia gravis (MG) may develop heart disease. Our data on 108 MG patients were examined to assess the type and frequency of this. 17 of 108 patients (16%) showed signs of heart disease which could be regarded as MG-related. 11 of these, of whom 5 died suddenly, had clinical symptoms, mainly arrhythmias. Signs of heart disease were most frequent in thymoma patients (5 of 10), and all 3 microscopically examined hearts from these patients showed a focal myocarditis. 44 spinal muscular atrophy patients serving as controls showed a 16% frequency of signs of heart disease of unknown etiology. However, only 1 of 44 spinal muscular atrophy patients (2%) had clinical symptoms as compared to 11 of 108 MG patients (10%). Together with the characteristic focal nature of the myocarditis and the microscopic similarities between lesions of heart and skeletal muscle, this indicates that the heart disease is specifically related to MG.

The effect of prazosin in congestive heart failure was assessed in 10 patients (age 39--69) years) with ischemic heart disease or cardiomyopathy in functional class II-IV (NYHA). All patients were treated with digitalis and diuretics in optimal doses. Mean (+/- S.E.M.) cardiac index (CI) was 2.2 +/- 0.2 l/min/m2 before and 2.3 +/- 0.1 one hour after oral administration of 2--4 mg prazosin (given as tablets) (p less than 0.10). Mean pulmonary capillary wedge pressure (PWP) fell from 24 +/- 4 to 20 +/- 4 mmHg (p greater than 0.10). Prazosin seemed to have a more beneficial effect on patients with markedly elevated PWP or reduced CI before prazosin administration. The effect of prazosin on heart rate and systolic blood pressure was insignificant. During a follow-up period of 1--20 months (mean 7.3), 2 of 7 patients treated with prazosin (2--4 mg daily) improved their clinical condition, one patient was unchanged and 4 patients died in progressive cardiac failure. The results indicate that some patients with severe heart failure may benefit from prazosin when conventional treatment has failed.

The clinical course in a patient with a combined intoxication with digitoxin (maximal serum level 357 nmol/l) and verapamil is described. The patient received two injections of digitalis-specific antiserum. No adverse reactions to the therapy was seen, and the antiserum markedly shortened the plasma half-life of digitoxin. In vitro studies indicate that digitoxin in concentrations seen during the intoxication may have an immunosuppressive effect, thereby reducing the risk of sensitisation to the antiserum.