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Biomedical subjects

G Vacca

Publications and source records attributed to G Vacca.

At least 109 records · Page 6Linked to original sources
PubMed1981

The effect of the venom of Bitis gabonica on mesenteric and external iliac blood flow. - A preliminary study in the dog.

The activity of the venom of Bitis Gabonica on mesenteric and external iliac circulation was investigated in four anaesthetized dogs. Venom doses of 0.125, 0.25 and 0.50 mg/kg were injected intravenously with an interval of 30 minutes between two successive injections. Following the first and the second dose, a transient fall of the resistance was observed in the mesenteric and especially in the external iliac vascular bed. Then, mesenteric resistance returned to normal, whereas external iliac resistance increased noticeable above the control value. After the third injection the animals died in a state of severe hypotension. It is note-worthy that during the transient vasodilation, mesenteric flow did not increase proportionally to the reduction of the relevant resistance, owing to the fact that BP fell more than would have been expected from the mesenteric vasodilation. This discrepancy seemed to depend on a more conspicuous reduction of the resistance in other vascular beds as observed in the external iliac circulation.

Animals↗
PubMed1981

Coronary circulation after suppression of barorecptor reflexes (preliminary observations).

In five anaesthetized open-chest dogs, aortic blood pressure, cardiac output and coronary flow were recorded. After the barorecptor reflex activity was suppressed by clamping both common carotid arteries and cutting both vagi nerves, aortic blood pressure and mean coronary flow increased. Phasic coronary flow further decreased in systole and increased in diastole, whereas coronary vascular resistance fell only when the suppression of the baroreceptor reflex activity had caused an increase of the heart rate.

Animals↗
PubMed1981

Haemodynamic effect of the suppression of ventricular tachycardia by atrio-ventricular captures.

In 10 anaesthetized open chest dogs, blood pressure, electrogram from the left auricular appendage or right atrium, peripheral ECG and cardiac output were recorded. Ventricular tachycardia was produced with aconitine and then suppressed by inducing atrial fibrillation or flutter-fibrillation either with aconitine or with electrical stimulation. After the capture of the ventricles by the supraventricular impulses, a haemodynamic improvement took place. This improvement is attributed to: I) beat to beat changes in the length of the cardiac cycles, whereby intermittent strong beats arise; II) restoration of the normal ventricular activation path and time course; III) the active contribution of properly timed atrial contractions, when present. The improvement was more evident when, after the capture, the ventricular rate was lower than during the ventricular tachycardia, because of a longer period available for the ventricular filling. It is believed that the reduction of the ventricular rate immediately after the capture is due to the suppression of the activity of the ventricular ectopic focus by the concealed conduction of high rate impulses coming from the atria.

Animals↗
PubMed1980

Vectorcardiographic analysis of prefibrillatory ventricular tachycardia in the rabbit.

In 10 urethan anaesthetized rabbits, VCG of acontine induced VT was studied. At the beginning of VT, both QRS and T loops arise and end regularly at the e point. Then, QRS loop opens and its end moves outside the E point, as a result of changes in ST segment. Later on, when ST segment disappears completely owing to an initial overlapping of the depolarization and repolarization processes, no arrest of the trace is observed between QRS and T loops. Lastly, immediately before the appearance of ventricular fibrillation, a progressive increase of the rate of VT above 400/min produces a fusion between the end of the T and the initial part ofn the next QRS loop. At this stage, no E point can be recognize. The results suggest that the transformation of VT into VF occurs through a delay and an overlapping of the depolarization-repolarization sequence.

Animals↗
PubMed1979

[Technical characteristics of an electromagnetic transducer of aortic flow, with reduced structure].

Sometimes a common probe of an electromagnetic flowmeter cannot be chronically placed around the aorta in the dog because its weight and shape can induce vascular injuries. Moreover it may occur that the record is disturbed by the movements of the probe around the vessel. The authors describe a new type probe that is capable to produce a reliable signal of the aortic blood flow, in spite of a reduced structure of its components. Obviously, such a signal, which is greater that the one produced by a coronary blood flow probe, must be properly amplified.

Animals↗
PubMed1979

Haemodynamic effect of the venom of Bitis Gabonica in the dog.

Intravenous injection of 0.125 mg/kg of venom of Bitis Gabonica in the anaesthetized dog produces an immediate but reversible decrease in total peripheral and coronary vascular resistance. Stroke volume show a transient increase followed by an irreversible reduction. A second dose of 0.25 mg/kg produces the same effect on total peripheral and coronary vascular resistance, but furtherly reduces the stroke volume. A third dose of 0.50 mg/kg kills the animal after an extreme reduction of the stroke volume. The progressive decrease of the stroke volume might be due to a failure of the ventricle to relax, whereas its transient increase immediately after the injection depends on the abrupt fall of the total peripheral resistance.

Animals↗
PubMed1979

Effect of multiple arterial haemorrhage on the coronary circulation.

In the open-chest anesthetized dog, multiple arterial haemorrhage induces a reduction of the mean coronary flow, an absote or relative increase of the phasic flow during the early ventricular ejection phase and a decrease during the remaining phases of the cardiac cycle. When blood pressure falls sharply during the haemorrhage, coronary vascular resistance increases, whereas it does not change or decreases when blood pressure falls slowly. Moreover, coronary vascular resistance decreases transiently after the stoppage of the haemorrhage.

Animals↗
PubMed1979

Effect of acute arterio-venous fistulae on mean and phasic coronary flow in the dog.

The effect of acute arterio-venous fistula on mean and phasic coronary flow was studied on 4 open-chest dogs. When the pressure is basically high, after the opening of the fistula the fall which coronary flow shows during the isometric systole occurs to a lesser extent; conversely, when the pressure is basically normal, the fall of the coronary flow may be absent.

Acute Disease↗