The yield of a diagnostic hospital dyspnoea clinic for the primary health care section

OBJECTIVE

To investigate the impact of a combined examination programme with treatment advice on patients from general practice with dyspnoea.

DESIGN

Prospective study with 6 months followup.

SETTING

Regional hospital offering care for patients from 74 general practitioners.

SUBJECTS

A total of 284 consecutive patients referred from general practice with dyspnoea.

INTERVENTIONS

Patients were subjected to a combined examination programme including physical examination, ECG, chest X-ray, lung spirometry, echocardiography and routine laboratory tests.

MAIN OUTCOME MEASURES

(i) Relationship between a diagnosis made by the referring general practitioner and the diagnosis based on the combined examination programme. (ii) The impact of the investigation programme and resulting therapeutic advice on dyspnoea after 6 months.

RESULTS

Only in 39% of the patients there was concordance of the diagnoses on referral and the diagnosis based on the examination programme. Heart failure and lung disease was suspected in 126 and 79 patients, respectively, but these diagnoses were confirmed in only one-third to half of the patients. Conversely heart failure was revealed in 13 of 107 patients not suspected of heart failure (12%) and lung disease in 45 of 154 patients not suspected of pulmonary disease (29%). A change of treatment was suggested in 64% of all patients. After 6 months, improvement of dyspnoea was seen in more than half of the patients. In patients in whom the changes of medical treatment were completed, 61% expressed improvement in dyspnoea, whereas improvement of dyspnoea was recorded in only 34% of patients in whom the recommended treatment advice was not taken (P < 0.01).

CONCLUSION

(i) In most patients it seems to be too difficult to establish the background of dyspnoea in general practice. (ii) There appears to be a substantial chance of improvement in patients with dyspnoea, in particular for patients who act on treatment advice based on an integrated examination programme; the chance of improvement is almost twice as good as in patients who are not capable to do so.

Risk assessment of left ventricular systolic dysfunction in primary care: cross sectional study evaluating a range of diagnostic tests

OBJECTIVES

To assess the probability of left ventricular systolic dysfunction without echocardiography in patients from general practice.

DESIGN

Cross sectional study using multivariate regression models to examine the relation between clinical variables and left ventricular systolic dysfunction as determined by echocardiography.

SETTING

Three general practices in Copenhagen.

SUBJECTS

2158 patients aged >40 years were screened by questionnaires and case record reviews; 357 patients with past or present signs or symptoms of heart disease were identified, of whom 126 were eligible for and consented to examination.

MAIN OUTCOME MEASURES

Clinical variables that were significantly (P<0.05) related to ejection fraction </=0.45 and their predictive value for left ventricular systolic dysfunction.

RESULTS

15 patients (12%) had left ventricular systolic dysfunction. The prevalence was significantly related to three questions: does the electrocardiogram have Q waves, left bundle branch block, or ST-T segment changes? (P=0.012); is resting supine heart rate greater than the simultaneous diastolic blood pressure? (P=0.002); and is plasma N-terminal atrial natriuretic peptide>0.8 nmol/l? (P=0.040)? Only one of 60 patients with a normal electrocardiogram had systolic dysfunction (2%, 95% confidence interval 0% to 9%) regardless of response to the other two questions. The risk of dysfunction was appreciable in patients with a yes answer to two or three questions (50%, 27% to 73%).

CONCLUSIONS

A normal electrocardiogram implies a low risk of left ventricular systolic dysfunction. Patients can be identified for echocardiography on the basis of an abnormal electrocardiogram combined with increased natriuretic peptide concentration or a heart rate greater than diastolic blood pressure, or both.

Correlation between serial changes in left-sided heart chambers and atrial natriuretic peptide and N-terminal pro atrial natriuretic peptide after a first myocardial infarction. An echocardiographic study

Dilatation of the left ventricle predicts morbidity and mortality after acute myocardial infarction. We compared serial echocardiographic examinations of the left atrium and ventricle with measurements of plasma atrial natriuretic peptide (ANP) and plasma N-terminal pro atrial natriuretic peptide (NT-proANP) in 22 patients during the first 6 months following a first myocardial infarction. ANP, but not NT-proANP, was found to be significantly correlated to the diastolic/systolic size of the left atrium (r = 0.58/0.60) and the systolic size of the left ventricle (r = 0.43) in the acute phase 2-4 days after infarction. At 10-12 days after the infarction, we found a significant correlation between all sizes of the left-sided chambers and ANP, whereas NT-proANP only correlated with the left atrial sizes. Three months after the infarction, all sizes of the left-sided chambers correlated with both ANP and NT-proANP, with the exception of a non-significant correlation between NT-proANP and the left atrial diastolic size. After 6 months only the area of the diastolic and systolic left atrium correlated with plasma ANP and only the systolic size of the left atrium correlated with NT-proANP. The percentage change in the size of the left atrium, but not the left ventricle, correlated significantly with the percentage change in both ANP (r = 0.57) and NT-proANP (r = 0.70). We conclude that the distension of the left atrium rather than the dilatation of the left ventricle is related to the concentration of ANP and NT-proANP after an acute myocardial infarction.

[Neurohormonal activity in heart insufficiency]

The maintenance of cardiac pumping ability in the presence of a primary disturbance of myocardial contractility and/or an excessive haemodynamic strain on the heart is dependent on several compensatory mechanisms. Particular attention has formerly been paid to the importance of the Frank-Starling mechanism and cardiac hypertrophy and dilatation in maintaining a blood supply sufficient to cover the metabolic needs of various tissues in heart failure. In recent years, however, it has been found that certain neurohormonal systems (the sympathetic nervous system, the renin-angiotensin-aldosterone system, atrial natriuretic peptide and several locally acting vaso-active substances) undergo considerable changes according to the degree of heart failure. These compensatory mechanisms support the circulation wholly or partially in acute heart failure, however sustained neurohormonal activation may be harmful in chronic heart failure, where several neurohormonal factors may be activated to ill-effect. The most significant neurohormonal systems and their importance in heart failure are reviewed on the basis of the available literature.

Neurohormonal systems during progression of heart failure: a review

In the presence of a primary disorder in myocardial contractility and/or extraordinary hemodynamic pressure on the heart, ventricular performance depends on several compensating mechanisms. In the past, studies were mostly focused on the importance of the Frank-Starling mechanism and the hypertrophy and dilation of the heart in maintaining a circulation sufficient for metabolic intake during heart failure. Recently, however, the existence of neurohormonal systems has been demonstrated (the sympathetic nervous system, the renin-angiotensin system, atrial natriuretic peptide and several locally produced vasoactive substances), which change considerably according to the severity of the heart failure. While these compensatory mechanisms support the circulation in patients with acute heart failure, in whole or in part, neurohormonal activation over an extended period of time might be harmful to patients with chronic congestive heart failure since several neurohormonal factors might be inappropriately activated. This article will review the key neurohormonal systems and their importance in heart failure on the basis of the current literature.

Atrial natriuretic peptide in congestive heart failure after acute myocardial infarction

The concentration of atrial natriuretic peptide, a newly discovered hormone produced in the atrial wall, was measured in 55 patients during the first 72 h after acute myocardial infarction. 37 patients became clinically congested, while 18 patients avoided this complication. 13 patients (9 congested and 4 uncongested) experienced tachycardia, known to raise the concentration of atrial natriuretic peptide both with and without congestive heart failure. In the remaining 42 patients, the congested group had a significantly higher plasma atrial natriuretic peptide concentration than the uncongested group (p < 0.05) on all 3 days. In the congested group the concentration of atrial natriuretic peptide did not normalize after initiation of treatment. We conclude that the concentration of atrial natriuretic peptide is increased in all patients with acute myocardial infarction and that the level of atrial natriuretic peptide declines during the first 24 h in all patients and normalizes in the uncongested patients while the level of atrial natriuretic peptide is still elevated (at least for 72 h) in the congested patients.

Plasma concentration of atrial natriuretic peptide at admission and risk of cardiac death in patients with acute myocardial infarction

OBJECTIVE

To compare the concentration of plasma atrial natriuretic peptide in patients with acute myocardial infarction with a healthy population and to determine whether a raised concentration of plasma atrial natriuretic peptide at admission was a predictor of mortality after acute myocardial infarction.

DESIGN

Patients with acute myocardial infarction were divided into a group with no congestion (class I) and a group with congestion (class II-IV) according to their highest Killip classification in the first 24 hours after infarction. The concentration of plasma atrial natriuretic peptide was measured at admission. On the basis of the concentration of atrial natriuretic peptide measured in the healthy population, patients were separated into two groups: a group with a high (greater than 200 pg/ml) and a group with a low concentration of atrial natriuretic peptide (less than or equal to 200 pg/ml). The patients were followed for three years.

PATIENTS

55 patients admitted to the coronary care unit within 12 hours of the appearance of symptoms of acute myocardial infarction were compared with 51 healthy individuals.

MAIN OUTCOME MEASURES

Plasma atrial natriuretic peptide, Killip class, mortality.

RESULTS

The patients had significantly higher concentrations of atrial natriuretic peptide than the healthy controls. Furthermore, patients with congestion had a significantly higher concentration of atrial natriuretic peptide than the uncongested group of patients. Total mortality was 34.5%. In the group with a low concentration of atrial natriuretic peptide the mortality was only 13.6%, whereas mortality was significantly higher (48.5%) in the group with a high concentration.

CONCLUSIONS

The measurement of atrial natriuretic peptide separated the patients into low and high risk groups after acute myocardial infarction.

[The reliability of serum potassium levels measured in blood from a central venous catheter]

A clinical investigation was undertaken to assess the agreement between serum potassium (S-K) (1) in the peripheral venous blood and S-K in ten samples of 2 ml blood taken via a central venous catheter (2) where fluid containing potassium had been infused prior to taking the blood-samples (3). The results revealed that in order that S-K in 95% (twice the SD) of the samples taken from the central venous catheter is to fall within +/- 0.5 mmol/l as compared with S-K in the peripheral blood, it is necessary to discard the first 12 ml of blood withdrawn.

Hypotension during exercise caused by venodilatation

A 54-year-old woman without organic heart disease presented with presyncopal symptoms during work. A decreased cardiac output was demonstrated by haemodynamic measurements during exercise. Treatment with fludrocortisone and ephedrine was initiated with a good haemodynamic and symptomatic result.

Physiological hypertrophy of the heart and atrial natriuretic peptide during rest and exercise

The influence of physiological cardiac hypertrophy on the concentration of plasma atrial natriuretic peptide was studied in six male athletes and six normally active, matched control men. They were examined by echocardiography during a graded exercise test on a bicycle ergometer. Plasma atrial natriuretic peptide was measured at rest, at each workload until exhaustion, and 15 and 30 minutes after the exercise test. Echocardiography showed that the athletes had a significantly larger left atrium, left ventricular end diastolic diameter, left ventricular posterior wall, interventricular septum, left ventricular ejection fraction, and left ventricular mass than the controls. The athletes performed significantly more work than the control group--325 W v 277 W. The plasma concentration of atrial natriuretic peptide rose by a mean factor of 2.76 (range 1.78-4.28) in all men from rest to maximum exercise. There were no differences between the athletes and the controls in the concentrations of plasma atrial natriuretic peptide at rest, at any workload, or at maximum workload. Neither was there any difference in the increase in plasma atrial natriuretic peptide between the groups. There was no correlation between the plasma concentrations of atrial natriuretic peptide and any of the variables measured by echocardiography. In healthy young men plasma atrial natriuretic peptide rises by a factor of about 2.8 during maximum exercise and the size of the chambers on the left side of the heart or left ventricular hypertrophy does not seem to influence the concentration of plasma atrial natriuretic peptide at rest or during exercise.

Atrial natriuretic peptide during the menstrual cycle

Plasma atrial natriuretic peptide levels were found to decrease from 82.5 pg/ml in the follicular phase to 55.8 pg/ml in the luteal phase in 10 normal menstruating women. The reduced level of plasma atrial natriuretic peptide could be a compensatory response to the natriuretic effect of the increased plasma progesterone in the luteal phase.