The importance of different atrioventricular intervals for exercise capacity

In order to determine whether different atrioventricular intervals influence the maximal exercise capacity, 15 patients with second degree or complete atrioventricular block and no signs of left ventricular failure were studied. They all had atrioventricular synchronous pacemakers. Maximal exercise tests (sitting bicycle ergometry) were performed at four different atrioventricular intervals (50, 100, 150, and 200 ms) and during rate-matched asynchronous ventricular pacing. The patients thereby served as their own controls. Ventricular rate, maximal oxygen uptake and minute ventilation were measured and perceived exertion estimated every minute. Different atrioventricular intervals did not affect the maximal exercise capacity, the maximal oxygen uptake, the perceived exertion or minute ventilation. Since the results were similar during atrioventricular synchronous pacing at various atrioventricular intervals and on rate-matched asynchronous ventricular pacing, this study supports previous findings that the important factor for maximal physical performance is not a preserved atrioventricular synchronization but the ability to increase the ventricular rate.

Myocardial infarction in patients with diabetes mellitus

The occurrence of diabetes mellitus and its complications and prognosis in an unselected consecutive series of patients with myocardial infarction (MI) was studied. Out of 341 patients 81 (24%) had diabetes. Comparisons were made between patients with and without diabetes. Age was higher and female sex more common among patients with diabetes. A considerable proportion of patients with diabetes were on digitalis when admitted (51%) compared to 20% of those without. Ventricular tachyarrhythmias requiring treatment did not differ between the two groups. High-degree AV-block was considerably more common among patients with diabetes (19%) than those without (7%; P less than 0.001). Mortality was higher in diabetic than in non-diabetic patients both during the hospital phase (25%, vs. 16%; P less than 0.02) and during one year of follow-up (53% vs. 28%; P less than 0.001). Diabetes was an independent prognostic risk factor for death (P less than 0.01). Fatal reinfarction was more common among diabetic patients (30%) than those without (14%; P less than 0.05). In conclusion diabetics with MI have a poor prognosis despite improvements in coronary care. The high late mortality is to a large extent related to a high proportion of fatal reinfarctions.

Effect of controlled-release metoprolol on blood pressure and exercise heart rate in hypertension: a comparison with conventional tablets

In a double-blind study with parallel groups a new controlled-release (CR) formulation of metoprolol, 100 mg once daily, was compared with conventional metoprolol tablets, 100 mg once daily, in 27 patients with primary hypertension. Exercise tests on a bicycle ergometer were undertaken 24 h after intake of the last dose of the drug following a four-week placebo run-in period and after four weeks of active treatment. Heart rate, measured in the supine position and during exercise at the highest comparable workload, was reduced significantly more by metoprolol CR (p less than 0.05), thus indicating a higher degree of beta 1-blockade at the end of the dose interval with metoprolol CR. There was a greater reduction in supine systolic pressure (p less than 0.05) but not in supine diastolic pressure after metoprolol CR than after conventional tablets at 24 h. There was no significant difference between the two groups with respect to reduction in systolic blood pressure during exercise. The 24-h plasma concentrations of metoprolol CR and conventional tablets correlated with the effects on heart rate, but not with blood pressure. The tolerability of metoprolol CR was comparable with that of metoprolol administered as conventional tablets. In conclusion, there was significantly greater beta 1-blockade 24 h after the intake of drug after metoprolol CR compared with conventional tablets.

Buccal versus sublingual nitroglycerin administration in the treatment of angina pectoris: a multicentre study

Buccal (Suscard) was compared with sublingual nitroglycerin (Nitromex) in 126 patients with stable angina pectoris. Following a dose adjustment period they were randomized to cross-over treatment, two weeks on sublingual and buccal nitroglycerin, respectively. The dosage of buccal nitroglycerin was 2.5 mg in 49% and 5.0 mg in 51%. The total number of treated acute anginal attacks was 31% less during the buccal compared to the sublingual nitroglycerin period (P less than 0.001) despite a reported physical activity level which was significantly higher during the buccal nitroglycerin period. The use of sublingual nitroglycerin and buccal nitroglycerin was considered equally simple by 67%, sublingual nitroglycerin easier by 19% and buccal nitroglycerin easier by 14% of the patients. Sublingual nitroglycerin was used prophylactically on 806 occasions and buccal nitroglycerin on 929 occasions (P less than 0.05) with success in 66% of the sublingual nitroglycerin-attempts and 74% of the buccal nitroglycerin-attempts (P less than 0.05). Considering only prophylactic use, buccal nitroglycerin was preferred by 81% and sublingual nitroglycerin by 4% (P less than 0.05). When given the opportunity only to select one of the two nitroglycerin formulations, 65% (P less than 0.05) preferred buccal nitroglycerin and 19% sublingual nitroglycerin. In conclusion, buccal nitroglycerin seems to be more efficacious than sublingual nitroglycerin. The explanation is probably that the two formulations are comparable in the treatment of acute anginal attacks, while buccal nitroglycerin has a more pronounced prophylactic effect due to its longer duration of action.

Work absenteeism and well-being in patients treated for hypertension

The purpose of this study was to analyse the effect of detection and treatment of hypertension on work absenteeism and other indicators of well-being. Because the study was performed as part of a trial comparing structured and regular hypertension care, we also analysed the impact of these different methods of organizing care. Matching for age and sex, three samples were drawn: one from regular medical care (N = 123) one from structured protocol care (N = 238) and one from normotensive subjects, aware of their blood pressure level (N = 128). Insurance data did not reveal any differences between the three groups in the amount of work absenteeism during a six-year period. Moreover, we found no short-term rise in work absenteeism during the first year after diagnosis. Finally, interviews failed to show significant differences between the three groups with respect to general satisfaction with life or other aspects of psychological well-being. We conclude that the patients treated for hypertension did not differ importantly from normotensive subjects with regard to illness-induced work absenteeism or other aspects of psychological well-being.

Hypertension case-finding in primary health care. Experience from the Skaraborg Hypertension Project

This study evaluates the efficacy of a hypertension case-finding program. During office hours (8.00 am to 5.00 pm weekdays), all patients visiting a Swedish primary health care center, had their blood pressure recorded using an automatic equipment. This was made irrespective of the reason for the visit. Analysis of a record sample showed that 56 +/- 4% (95% confidence) of the 40-69 year-old fraction of the population (N = 5,806) served by the center attended the center during a two-year period. Fifty-two percent (N = 3,025) had their blood pressure checked and one percent (N = 65) fulfilled the criteria for hypertension (greater than 170/greater than 105 mmHg at three different times if aged 40-60 years; greater than 180/greater than 110 mmHg greater than 60 years). We conclude that case-finding for hypertension has low efficacy when performed in day-time primary health care.

Buccal versus sublingual glyceryl trinitrate administration in the treatment of angina pectoris. A Swedish multicentre study

126 patients with chronic exercise-induced angina, who were accustomed to the use of sublingual glyceryl trinitrate, were entered into a multicentre 2-week crossover comparison of sublingual (Nitromex) and buccal (Suscard) formulations of glyceryl trinitrate. Before randomisation the patients underwent a training period when doses of the buccal formulation were individualised. There were 31% fewer attacks with the buccal formulation, and more patients reported higher physical activity on the buccal compared with the sublingual formulation (30% vs 16%). The buccal formulation was also more effective when glyceryl trinitrate was used prophylactically to prevent expected attacks, being effective in 74% of attempts compared with 66% for the sublingual formulation (p less than 0.05). More patients preferred the buccal route of administration for prophylactic use (81% vs 4%, p less than 0.05). Similarly, when asked to select which they would use in future, 65% of patients preferred the buccal formulations (p less than 0.05), 19% preferred sublingual glyceryl trinitrate, and 16% did not express any preference.

Central haemodynamic effects of metoprolol early in acute myocardial infarction. A placebo controlled randomized study of patients with low heart rate

The central haemodynamic effects of metoprolol in patients with acute myocardial infarction and with heart rate less than or equal to 65 beats min-1 have been investigated in a randomized double-blind trial. The aim was to study the tolerance in this selected patient group and to assess possible differences in haemodynamic response amongst patients with initially higher heart rates. Exclusion criteria were: treatment with beta blockers; heart rate greater than 65 beats min-1; systolic blood pressure less than 110 mmHg; and physical signs of serious heart failure. Following pulmonary artery catheterization, 22 patients were randomized to metoprolol 15 mg i.v. + 50 mg q.i.d. orally (N = 12) or placebo (N = 10). Central pressures and cardiac output were recorded before and during the 24 hours after drug administration. There was a significant fall in heart rate, cardiac index, rate pressure product and stroke work index of 10-20% in the metoprolol, compared with the placebo group. The differences were most pronounced immediately after the metoprolol injection. The pulmonary artery capillary wedge pressure was not significantly changed. The overall haemodynamic response to metoprolol was similar to that reported in patients with acute myocardial infarction and heart rate above 65 beats min-1. Tolerance was good.

The future of single chamber pacing

Although dual chamber pacemakers have held much interest in pacing over the past several years, single chamber pacing remains the modality of choice, worldwide, in the greatest proportion of patients. Atrial or ventricular demand pacing is safe and effective in the majority of patients. In addition, sensors may be used to increase ventricular pacing rate in order to improve cardiac performance.

Holter-monitored heart rhythm during atrioventricular synchronous and fixed-rate ventricular pacing

The purpose of this investigation was to study rate variability during normal everyday activities among physiologically paced patients. A comparison of the spontaneous occurrence of arrhythmias with ventricular inhibited pacing was also made. VDD pacemakers in 44 patients were randomly programmed to three-week long periods of VVI (70 bpm) or VDD (back-up rate 40-50 bpm, upper rate 125-150 bpm) pacing, respectively. A Holter ECG was recorded during the last 24 hours of each period. Although the total number of QRS complexes was similar in the two pacing modes (4.3 X 10(6)/24 hours), the rate span was extensively utilized during VDD pacing. During VDD pacing, only five patients of 39 with a programmed upper rate of 150 bpm reached this limit, while one of five with 125 bpm reached that rate. Occasional episodes of pacing at the back-up rate of 40 or 50 bpm were recorded in 33 patients. Episodes of asymptomatic rhythm disturbances were recorded in both pacing modes. No significant differences existed as regards ventricular tachyarrhythmias between the two modes of pacing and it did not seem that the incidence was higher than could be expected in a patient population of the present age. Since severe AV block does not permit conduction of atrial impulses during VVI pacing, no direct comparison between the two pacing modes can be made concerning atrial tachyarrhythmias. Only one episode of pacemaker-mediated SVT was found, and this was unsymptomatic.

Variability, prediction and prognostic significance of chest pain in acute myocardial infarction

The variability of chest pain is described in 389 patients with acute myocardial infarction. Whereas 17% were free from severe pain after arrival in hospital, 11% required more than 10 analgesic injections. In 27% of the series analgesics were given more than 24 h after arrival in hospital. Predictors for the severity of chest pain were the rate-pressure product and degree of chest pain soon after arrival in hospital as well as electrocardiographic signs of myocardial infarction at entry. Patients with more severe chest pain had a higher 2-year mortality rate and a higher incidence of ventricular fibrillation and congestive heart failure during hospitalization.

The haemodynamic importance of atrioventricular synchrony and rate increase at rest and during exercise

To compare the added haemodynamic importance of atrioventricular synchrony to rate increase, we studied 10 patients, healthy except for atrioventricular block, treated with atrioventricular synchronous pacemakers. Haemodynamic data were obtained by brachial and pulmonary arterial catheterisation. Recordings were made at rest and during upright bicycle ergometry at two submaximal work loads (50% and 80% of maximal aerobic exercise tolerance). The investigation was first performed in the atrioventricular synchronous mode of pacing (VDD) and later repeated during fixed-rate ventricular pacing (VVI) at ventricular rates adjusted to the levels achieved during atrioventricular synchronous pacing. At rest (mean rate 74 bpm), preserved atrioventricular synchrony increased cardiac output (5.0 +/- 0.7 l min-1; mean +/- SD) compared with asynchrony (4.5 +/- 1.0; P less than 0.05), owing to a higher stroke volume (70 +/- 19 versus 64 +/- 22 ml; P less than 0.05), illustrating the importance of the atrial contribution to ventricular filling. During exercise at 50% (mean rate 122 bpm) and 80% (mean rate 146 bpm) of maximal aerobic tolerance, there were no significant differences in cardiac output (50%: VVI 10.1 +/- 2.5, VDD 10.5 +/- 1.6 NS; 80%: VVI 12.8 +/- 4.1, VDD 12.3 +/- 3.5, NS) or in stroke volume (50%: VVI 83 +/- 23, VDD 88 +/- 17, NS; 80%: VVI 89 +/- 32, VDD 85 +/- 27, NS). We conclude that the capacity for rate increase is of major importance while preserved atrioventricular synchrony seems to be much less important for the ability of the individual to increase cardiac output during exercise, at least in patients without myocardial disease.

Physiological versus single-rate ventricular pacing: a double-blind cross-over study

Previous comparisons of physiological and single-rate ventricular pacing are mostly based on open studies. The present investigation was designed to control possible biases of such a study design with the aim to investigate effects of the two pacing modes on maximal and submaximal exercise tolerance and the subjective feeling of well-being of the patients. Forty-four patients treated with atrioventricular synchronous pacemakers for more than 12 months participated in the study. Their pacemakers were randomly programmed to one 3-week long period of ventricular inhibited and a similar period of atrioventricular synchronous ventricular inhibited pacing. Thereafter, they went through echocardiography, symptom-limited maximal exercise test and answered a questionnaire on subjective symptoms. The study was blind since neither the patients nor the physician conducting the exercise tests were informed of pacing mode. The mean maximal exercise tolerance increased 14% (p less than 0.01) on atrioventricular synchronous pacing. Arterial lactate, respiratory rates and perceived exertion ratings during submaximal levels of exercise were higher on ventricular inhibited pacing, as well as symptoms scored during the two 3-week periods. A majority of patients improved their functional class during atrioventricular synchronous pacing and preferred the physiological pacing mode.

Long term experience of felodipine in combination with beta-blockade and diuretics in refractory hypertension

Felodipine, a new dihydropyridine, was given to 58 hypertensive patients in combination with an adrenergic beta-receptor antagonist and a diuretic agent. In all but 2 patients the blood pressure was unsatisfactorily controlled on standard triple therapy, i.e. alpha beta-blocker, a diuretic and a vasodilator. A 48-week follow-up was completed by 54 patients. After an initial dose titration period, the maintenance dose of felodipine was 5 mg twice daily in 14 patients and 10 mg twice daily in 34 patients. In the remaining 6 patients, the dose ranged from 5 mg every morning to 25 mg twice daily. The dosages of beta-blocking agent and diuretic were considerably reduced during the study period. Mean supine blood pressure was reduced from 170/101 mm Hg on triple therapy before felodipine to 145/86 mm Hg (p less than 0.001) after 2 weeks on felodipine. This improvement was sustained throughout the study and was measured at 144/86 mm Hg (p less than 0.001) after 48 weeks. There was no increase in resting heart rate and no orthostatic fall in blood pressure. Bodyweight was not increased and felodipine was generally well tolerated. Three patients were withdrawn owing to side effects and 1 was socially non-compliant. It is concluded that felodipine is a potent and well tolerated vasodilator, and will be useful in the long term combination treatment of previously refractory hypertension.

Antihypertensive effect of felodipine combined with beta-blockade. A comparison between 2 and 3 daily dosages

24 hypertensive patients, who were not satisfactorily controlled (diastolic blood pressure greater than 95 mm Hg) with beta-blockers alone were randomised to 2 treatment groups where felodipine was administered for 2 weeks in a total daily dose of 15 mg divided in 2 or 3 doses. Following a 2-week placebo washout period, the patients were switched to the alternative dose regimen in a double-blind crossover manner. Blood pressure was measured with standard techniques and was also non-invasively monitored for 24 hours at the end of each dose regimen period and at the end of the intermediate placebo period. Mean arterial blood pressure at the end of the placebo run-in period was 169/105 mm Hg. Felodipine 5 mg thrice daily reduced blood pressure by 20/9 mm Hg and felodipine 7.5 mg twice daily by 17/9 mm Hg (p less than 0.05). The difference between the 2 dose regimens was not statistically significant. When 24-hour blood pressure measurements for the 2 dose regimens were compared, there were no statistically significant differences. Both regimens reduced the 24-hour blood pressure significantly compared with placebo. Two patients were withdrawn during the study, 1 before felodipine treatment started and the other due to diarrhoea and flushing related to felodipine. Otherwise felodipine was generally well tolerated.

Economic evaluation of a Swedish medical care program for hypertension

A Hypertension Care Program, developed in cooperation between physicians and nurses in both primary care and at the hospitals in the area, was implemented in the Skaraborg County, Sweden in 1977. The Program, which provided for the establishment of hypertensive clinics at outpatient units and referral to medical clinics, was clearly aimed towards giving nurses increased responsibility for hypertensive care. The Skaraborg Program has been evaluated from several important perspectives. A terminal population study showed better blood pressure control among the hypertensive patients within the program area than within the control area. The economic evaluation indicates that hypertensive care according to the Program is somewhat less resource demanding than conventional hypertensive care. Since the medical effects of hypertensive care were improved without increased demand for resources, the structured Care Program was more cost-effective than conventional care.

Clinical efficacy of hydralazine in chronic heart failure: one-year double-blind placebo-controlled study

In a placebo-controlled trial 62 patients with chronic congestive heart failure (CHF) (New York Heart Association class III) had hydralazine (149 +/- 11 mg daily) or placebo added to conventional therapy. During 12 months' follow-up 27 patients dropped out, 15 of 32 in the hydralazine group and 12 of 30 among the control subjects. The 1-year mortality rate was 28% in the hydralazine group compared to 27% in the control group. Symptomatic improvement was noted in both groups; however, it was gradually more pronounced in the actively treated group with a statistically significant difference between the two groups at month 12 (p less than 0.05). The hydralazine patients increased their exercise capacity 25%, from 53 +/- 3 watts at month 0 to 67 +/- 4 watts at month 12 (p less than 0.01). No improvement in exercise capacity took place in the placebo group. A significant improvement in chest x-ray examination was found with hydralazine (p less than 0.01) in contrast to a significant deterioration among the control subjects (p less than 0.05). Thus, we conclude that hydralazine used in chronic CHF has beneficial clinical effects during long-term treatment.