Sleep and cardiac rhythm in healthy men.

Cardiac rhythm during sleep was analysed in 168 healthy men aged 19 to 30 (mean 21.8) years using continuous nocturnal ECG recordings. Thirty five of the subjects were endurance athletes; 99 were recorded at home and 69 at a garrison during military service. The number of short term (less than one min) accelerations of heart rate of more than ten beats per minute ranged from 1.3 to 14.3 per hour; the number or accelerations (greater than one min) of more than 25 beats per minute typical of nocturnal restlessness ranged from zero to 6.1 per hour. The accelerations indicating nocturnal restlessness were more common during recordings done at the garrison than at home (2.2 per hour vs 1.3 per hour, P less than 0.01), whereas the short term accelerations were not (5.8 per hour vs 5.1 per hour, NS). Sinus pauses exceeding 2.00 sec occurred in 17 men (13 in athletes), occasional second degree atrioventricular block in 19 (eight in athletes) and ventricular premature beats in 37. Eighty-two per cent of sinus pauses, 83% of second degree atrioventricular blocks, and 81% of ventricular premature beats (when less than ten in the same subject) were associated with short term changes in heart rate. In conclusion, rapid changes in heart rate, presumably as a results of autonomic activation, are closely associated with most arrhythmias in healthy men during sleep, whereas changes in heart rate typical of nocturnal restlessness have little arrhythmogenic effect.

Quinapril and blood lipids.

To assess the effects of angiotensin-converting enzyme inhibition with quinapril on blood lipid profile, serum total cholesterol and triglycerides, together with high-density and low-density lipoprotein cholesterol were analysed in 23 hypertensive patients receiving either placebo (7 patients) or quinapril hydrochloride (16 patients). After 12 weeks of therapy there were no significant changes in blood lipids in either group. No unfavourable changes in blood lipid profile were observed even after 1 year of therapy with quinapril hydrochloride in 13 patients.

The Finnish sauna and cardiovascular diseases.

From time to time it has been claimed that the thermal stress caused by sauna bathing can be harmful to persons with cardiovascular disorders. Furthermore, elderly persons in general, who have experienced no symptoms from bathing, have also been cautioned. However, several studies carried out in Finland did not confirm the adverse effects of bathing on the elderly and cardiovascular patients. The controversial results obtained in Finnish and in some foreign studies are at least partly due to the different test conditions. The typical Finnish sauna bath is safe, and even patients who have recovered from acute myocardial infarction can enjoy the sauna without incurring any harmful cardiovascular effects.

Antihypertensive and biochemical effects of different doses of hydrochlorothiazide alone or in combination with triamterene.

The antihypertensive and biochemical effects of 25 mg hydrochlorothiazide alone or 50 mg hydrochlorothiazide alone or in combination with triamterene (either 37.5 or 75 mg) once daily were studied in 26 patients with essential hypertension. After a 5-week run-in period the patients were randomized to receive active therapy in a cross-over manner. Each treatment period lasted 3 months. All drugs significantly (p less than 0.01) lowered both systolic and diastolic blood pressure. There were no differences in blood pressure between the medication periods. Serum potassium concentration was slightly lower during all medication periods than during the run-in period. This change was statistically significant (p less than 0.01) only on 50 mg hydrochlorothiazide daily. There were no significant changes in serum magnesium during any of the periods compared to the run-in period. The lowest values were recorded on 50 mg hydrochlorothiazide alone and the highest on 50 mg hydrochlorothiazide plus 75 mg triamterene daily. A slight increase in serum urate was recorded in all medication periods compared to the run-in period. No significant changes were observed in serum total cholesterol, HDL cholesterol or triglycerides between any of the periods. It can be concluded that 25 mg of hydrochlorothiazide is as effective in lowering blood pressure as higher doses of the diuretic. Higher doses of thiazides will in some patients cause adverse metabolic reactions of which the fall in serum potassium and magnesium is effectively hindered by triamterene.

Ambulatory electrocardiographic findings in young athletes between 14 and 16 years of age.

Ambulatory electrocardiographic recordings were obtained from 35 male athletes between 14 and 16 years old, and from 35 male non-athlete controls of the same ages, in order to determine the effects of regular physical training on cardiac electrical activity. In the young athletes, the heart rates were significantly (P less than 0.01) lower than in the nonathletes. Sinus intervals over 2.00 s were present in five athletes (14%) and one control (3%). First-degree atrioventricular block was detected in eight athletes (23%) and four controls (11%), and second-degree block was detected in seven athletes (20%) and one control (3%) (P less than 0.05). Ventricular premature beats were present in 60% of athletes and 57% of controls. The bradycardia in athletes did not predispose to ventricular ectopic activity, since heart rates at the times of occurrence of extrasystoles were higher in athletes than in controls. Even after two years of regular physical training there are significant differences in sinus nodal function and atrioventricular conduction as between young athletes and controls.

Role of dietary potassium and magnesium in diuretic-treated patients with cardiac insufficiency.

The role of daily dietary intake of potassium and magnesium in the maintenance of potassium balance was studied in 104 digitalized outpatients with chronic cardiac insufficiency receiving 50 mg hydrochlorothiazide twice daily for 6 weeks. The food consumption data were collected once a week by the 24-hour recall method during the 1st, 2nd and 3rd weeks of the investigation. Serum potassium and magnesium values were followed throughout the study, and total body potassium was measured at the end. During the hydrochlorothiazide treatment, potassium and magnesium levels decreased significantly (p less than 0.001). 46% of the patients became hypokalemic (serum potassium less than or equal to 3.5 mmol/l), hypokalemia being more common (64%) in the patients with a concomitant decrease (-0.063 +/- 0.08 mmol/l) in serum magnesium values. Mean intake of potassium and magnesium was 3.4 g and 299 mg in females and 4.2 g and 380 mg in males, respectively. There was no significant difference in the daily intake of potassium and magnesium between the patients becoming hypokalemic and those remaining normokalemic.

Ambulatory electrocardiographic recording in mild or moderate myotonic dystrophy and myotonia congenita (Thomsen's disease).

Ambulatory electrocardiographic recording (AER) was performed on 27 adult patients with mild or moderate myotonic dystrophy (MD) and in 12 adult patients with mild myotonia congenita (MC) to determine whether characteristic arrhythmias and conduction disturbances occur in the early stages of these myotonic disorders. In MD and MC, AER showed at least one finding regarded as normal in 93% and 0% of cases, respectively. The most common abnormalities in MD were first degree atrioventricular (A-V) block (in 70% of cases) and QTc greater than or equal to 0.46 s (in 33%). Abnormal sinus intervals and frequent second degree A-V block were rare, each occurring in 4% of patients. Ventricular tachycardia did not occur. It is concluded that signs of involvement of cardiac conductive tissue in the MD disease process are very common, even in the early stages. Delayed A-V conduction in the most common single finding. Sinus nodal dysfunction, severe disturbances in A-V conduction, and ventricular arrhythmias are not common in mild disease. Repeated AER is indicated, to evaluate whether conduction disturbances in MD are progressing.

Ambulatory electrocardiographic recording in endurance athletes.

Data from ambulatory electrocardiographic recording in 35 highly trained endurance athletes and in 35 non-athletic controls of similar ages are given. The minimal, mean hourly, and maximal heart rates were significantly lower in the athletes. Thirteen athletes (37 . 1%) but only two controls (5 . 7%) had sinus pauses exceeding 2 . 0 seconds. First degree atrioventricular block was observed in 13 athletes (37 . 1%) and five controls (14 . 3%), second degree Wenckebach type block in eight athletes (22 . 9%) and two controls (5 . 7%), and second degree block with Mobitz II-like pattern in three athletes (8 . 6%) and no control. All athletes with Mobitz II-type pattern also had first degree and Wenckebach-type second degree atrioventricular block. The behavior of sinus rate on development of atrioventricular block varied, not only interindividually but also intraindividually, from absence of change to an increase or decrease in most subjects in both study groups. A decrease in sinus rate on appearance of atrioventricular block was found constantly in only two athletes and one control. Atrioventricular dissociation with junctional rhythm occurred in seven athletes (20%) and with ventricular rhythm in one athlete. Neither of these phenomena was seen in the group of controls. The athletes had slightly fewer ventricular extrasystoles than controls, and no athlete had ventricular tachycardia, whereas two controls had ventricular tachycardia.

Tienilic acid in patients with impaired renal function.

Diuretic therapy is usually accompanied by biochemical changes, such as hypokalemia, impaired glucose tolerance and hyperuricaemia. Tienilic acid is a new long-acting diuretic with antihypertensive effect, combined with uricosuric property. For the purpose of evaluating the effect of tienilic acid in patients with impaired renal function, eleven patients with hypertension and slight to moderate renal impairment were randomized to either hydrochlorothiazide or tienilic acid therapy. During eight weeks of treatment no changes occurred in serum-creatinine, creatinine-clearance, serum-sodium, or urea. Despite renal impairment, serum uric acid decreased during tienilic acid treatment. Compared with placebo, a significant decrease in uric acid was seen as early as after one week of treatment (p less than 0.01) and after 8 weeks the difference was still of the same order (p less than 0.01). During hydrochlorothiazide therapy, serum uric acid increased progressively. The difference was p less than 0.002 at 4 weeks and p less than 0.0005 at 8 weeks of treatment, compared with placebo. The results of this study show that the uricosuric effect of tienilic acid is maintained in patients with mild to moderate renal impairment.

Treatment of hypertension in the elderly with labetalol.

The response of elderly hypertensive patients to labetalol, possessing alpha- and beta-blocking properties, was studied. The dosage was first titrated out and assessed in a double-blind cross-over trial. Altogether 24 patients were treated for one year. The dosage established during the titration period maintained its efficacy. In most cases 200 mg labetalol daily gave satisfactory result. The side-effects were few. The only reason for discontinuance of the drug was gastrointestinal discomfort. Because of the low dosage, the typical side-effects of beta-blockade were lacking and alpha-blockade seemed to be well tolerated. The normal precautions in the treatment of elderly hypertensive patients should be observed.

Ambulatory ECG recording in patients referred because of syncope or dizziness.

Data are presented on patients referred for ambulatory ECG recording because of syncope or dizziness during a 2-year period. Of the 272 consecutive patients subjected to the recording, 107 (39.3%) had syncope or dizziness as the main indication for referral. Sixteen of these patients (14.9%) experienced the presenting symptom during the recording, and in 8 (50%) of these the simultaneous ECG finding was interpreted as causative. In patients who were symptom-free during the recording, sinus arrests exceeding 2.5 seconds seemed to be a valuable finding to support the cardiac aetiology of the syncopal symptoms, whereas the diagnostic value of second degree AV block with either Wenckebach or Mobitz II like patterns, as such, and of ventricular tachycardia remained mostly unsettled.

A comparison of two cardioselective beta-blockers with different ancillary properties in the treatment of hypertension.

In a double-blind crossover study the antihypertensive effect of acebutol (I.S.A. and M.S.A.) 400 to 800 mg daily was compared with that of metoprolol (non-I.S.A. and non-M.S.A.) 200 to 400 mg daily. Blood pressure and heart-rate were measured sitting, lying and post-exercise. Twenty-eight patients entered the trial, but 4 were withdrawn for reasons not connected with active treatment. There was no significant difference between the drugs in their ability to reduce the systolic and diastolic blood pressure sitting, lying or post-exercise or reduce the heart-rate post-exercise. Metoprolol reduced the heart-rate sitting and lying to a significantly greater degree (p less than 0.05) than acebutolol. While the antihypertensive effect seems to be entirely dependent on beta-blockade, the I.S.A. may still have some value for patients with a low heart rate at rest.

Ventricular arrhythmias during exercise testing, jogging, and sedentary life: a comparative study of healthy physically active men, healthy sedentary men, and men with previous myocardial infarction.

The occurrence of ventricular arrhythmias during exercise testing, jogging, and sedentary life with and without preceding exercise was studied with the aid of ambulatory electrocardiographic monitoring in healthy physically active men, healthy sedentary men, and men with previous myocardial infarction (15 men in each group). Ventricular premature beats of the same grade were found during exercise testing and jogging in ten of the 15 healthy physically active men, in ten of the 15 healthy sedentary men, and in eight of the 15 men with previous myocardial infarction. When unifocal ventricular premature beats were omitted, the corresponding figures were 14/15, 11/15, and 15/15, respectively. Healthy physically active men had less ventricular arrhythmias in all of the tested situations. The greatest number and also the highest grades of ventricular arrhythmias during the exercises were found in healthy sedentary men, whereas the men with previous myocardial infarction had ventricular arrhythmias more during sedentary life.

Maintenance of potassium balance during diuretic therapy.

The relative efficacies of potassium chloride, amiloride, triamterene and spironolactone in maintaining potassium balance were studied in 40 patients with essential hypertension receiving diuretic therapy. The preparations were administered in random order in a cross-over manner. In 31 patients treated with 50 mg hydrochlorothiazide daily, addition of 1500 mg potassium chloride daily was the weakest and 50 mg spironolactone daily the most effective agent for maintaining serum potassium. Amiloride (5 mg daily) and triamterene (75 mg daily) were less effective and equally so. Similar results were obtained with 9 patients treated with double dosages of the diuretic and supplements. Despite changes in serum potassium, total body potassium remained constant throughout the trial.