Elliot Shinebourne

EFFECTS OF BETA-ADRENERGIC BLOCKADE DURING EXERCISE IN HYPERTENSIVE AND ISCHÆMIC HEART-DISEASE

Abstract In ten patients with hypertension and eight with angina pectoris, β-adrenergic blockade with a single intravenous injection of propranolol produced a decrease in systolic and diastolic blood-pressure, heartrate, cardiac output, and left ventricular work at rest and during walking exercise. The effects were more striking in hypertensive patients than in those with ischaemic heart-disease. Six patients with hypertension and four with ischaemic heart-disease showed no essential difference in the haemodynamic findings in a second test period after a placebo injection. The decrease in blood-pressure after propranolol was due entirely to the effect on the heart, there being no change in the peripheral resistance. The findings suggest that propranolol should be a useful agent for the treatment of hypertension and angina pectoris.

Apnoeic episodes induced by smothering: two cases identified by covert video surveillance.

Recurrent cyanotic episodes associated on some occasions with loss of consciousness due to cerebral hypoxia were investigated by long term tape recordings of breathing activity, oxygen saturation, air flow, electrocardiographic activity, and in some cases electroencephalographic activity. In 51 infants and children the mechanisms for the cyanotic episodes were identified (prolonged expiratory apnoea in 45, sleep related airway obstruction in three, seizure induced apnoea in one, behaviour induced apnoea in one). In one child apnoea was suspected as being caused by suffocation (smothering) by the mother. This was confirmed after enlisting the help of the police, who undertook covert video surveillance during cyanotic episodes. Each cyanotic episode was associated with a pattern of disturbance on the multichannel tape recordings which may be pathognomonic of this type of apnoea. A second infant with cyanotic episodes in whom smothering was suspected was referred for similar investigation after the availability of video recordings became established. Maternal smothering was again supported by specific patterns on multichannel tape recordings and confirmed by video surveillance. Diagnosis by video surveillance produces unequivocal evidence in these cases and avoids the need for medical and nursing staff to confront the mother with a possibly incorrect suspicion or in a court of law.

Haemodynamic studies in hypertensive patients treated by oral propranolol

Haemodynamic studies have been performed in 9 patients whose blood pressures had been satisfactorily controlled with oral propranolol for 7 to 29 months. A postural drop of blood pressure or a fall of blood pressure on exercise did not occur. Pulse rate and cardiac output were below normal at rest and on exercise; peripheral resistance was high. The results are similar to those obtained in a comparable group of hypertensives after acute administration of propranolol. These findings are discussed in relation to the mode of action of propranolol in hypertension.

Selective cardiac sympathetic blockade as an adjunct to bronchodilator therapy

It has been shown in nine asthmatic patients that practolol, a selective cardiac beta-adrenergic antagonist, successfully blocks the unwanted tachycardia and palpitation following isoprenaline inhalation without hindering the beneficial bronchodilator action of the drug. Practolol is a useful adjunct to bronchodilator therapy in the management of bronchial asthma.

A Qualitative Distinction between the Beta-Receptor-Blocking and Local Anesthetic Actions of Antiarrhythmic Agents

Fragmented cardiac sarcoplasmic reticulum was isolated by differential centrifugation from canine myocardium. The effects of propranolol, quinidine, lidocaine (lignocaine) and tetracaine (amethocaine) on calcium uptake in sarcoplasmic reticulum in vitro were then measured. All the drugs are antiarrhythmic agents with local anesthetic activity, but propranolol and quinidine are known also to have beta-receptor-blocking actions in that they can prevent the cardiac effects of isoprenaline and depress the myocardium. Lidocaine and tetracaine do not generally depress the heart and had no effect on the calcium uptake, but propranolol and quinidine both significantly inhibited it. It was concluded that the antiarrhythmic actions of propranolol (and quinidine) may be independent of beta-receptor-blocking activity, and that the safety of lidocaine as an antiarrhythmic agent may be related to a lack of effect on the sarcoplasmic reticulum.

Significance of Electrocardiographic Changes in Hypertension

Studies in 17 hypertensive patients showed that the electrocardiographic features of T-wave inversion and S–T segment depression distinguish those patients with higher systolic blood pressures. They do not indicate impaired cardiac function.

EFFECT OF WALKING ON BLOODPRESSURE IN SYSTEMIC HYPERTENSION

Abstract The effect of walking on the arterial bloodpressure (B.P.) and cardiac output has been investigated in seventeen patients with systemic hypertension. The systolic pressure becomes higher on exercise, but the rise is not progressive as the work-load is increased. In many patients the cardiac output is lower than normal at rest and during exercise, suggesting left-ventricular disease. The systemic resistance is abnormally high at rest, and although the resistance falls on exercise the values remain greater than normal in most patients. A high resistance on exercise distinguishes severe hypertensives. The casual B.P. gives a better estimate of the B.P. on exercise than the basal reading obtained after several days in hospital. Labile hypertensives, with normal B.P. at rest after a few days in hospital, show a brisk rise in systolic B.P. on exertion to levels similar to those found in patients with fixed hypertension. The cardiac effects of hypertension seem to be more closely related to the casual and the exercising B.P.S than to the basal pressure, and patients with labile hypertension should not necessarily be regarded as having a benign form of the disease.

MEDICALLY SUPERVISED HOLIDAYS FOR DIABETIC CHILDREN

Abstract Sending a diabetic child to a holiday camp for a fortnight can be of therapeutic benefit both to him and to his family. These camps are open to all diabetic children aged from 6 to 17 years who live in Great Britain*.