'n Ondersoek van die hoër-dinamiese funksies van die hart by bokke en konyne

Abstract

The object of this investigation was to use the technique of blood flow measurement in order to assess the higher dynamic functions of the heart in rabbits and goats. Rabbits and goats of different species have been used in this investigation . Parameters, for example the electrocardiogram, phonocardiogram, blood flow velocity in the thoracic aorta and its time derivatives, have been used as well as the ultra-low frequency accelerati on ballistocardiogram and blood pressure of rabbits. Attention was specially given to the flow parameters ; the flow velocity in the aorta was established with the Doppler ultrasonic flow meter and the amplitudes and Q-time intervals were measured. Due to the lack of knowledge about the blood flow in the aorta of goats and rabbits, the values for normal animals were first determined . Cardiovascular changes were introduced by intraveneous administration of drugs such as adrenaline, noradrenaline, acetylcholine, amyl nitrite and pitressin and their effects on the different parameters were studied. From these results it is concluded that a relationship exists between the flow parameters and the other parameters used. A marked similarity has been established between the IJ wave of the ultra-low frequency acceleration ballistocardiogram and the time-derivatives of the blood flow velocity. The technique of blood flow measurement can thus be used successfully in conjunction with other methods, in the

establishment of the -cardiovascular changes such as the myocardial contraction and peripheral resistance o In a great variety -of normal and experimental circumstances the technique of the Doppler ultrasonic flowmeter provides opportunities -for studying the higher dynamic heart functions of large unanaesthetized animals in their normal upright position and small anaesthetized animals. The technique therefore also offers the possibility of studying plant toxications such as gousiekte and tulip poisoning among sheep and goats.