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The circulatory changes after full therapeutic doses of digitalis, with a critical discussion of views on cardiac output
300
THE
AMERICAN
HEART
JOURNAL
The results show that during aortic insufficiency the diastolic size is larger and the left ventricular discharge is increased from 16 to SS prr cent in different cspcri mcnts, on an average 36.4 per cent. Factors cjthrr than heart rato and sizr of leak are responsible for the variations. In the discussion it is pointed out that changes in heart size without data concerning the stroke volumes of the left ventricle are of no value in determining the percentile regurgitation, but that the percentile changes in st,roke volume of the left ventricle give by inference a fair estimate of the percentile regurgitation. The conclusion is reached that approximately one-third of the discharge during systole regurgitates through insufficient valves during diastole.
Dock, W., and Tainter, M. L.: The Circulatory Changes After Full Therapeutic Doses of Digitalis, With a Critical Discussion of Views on Cardiac Output. J.
Clin.
Investigation
8:
467,
1930.
Under experimental conditions in dogs a fall of venous pressure regularly accompanied the diminished cardiac output following a full therapeutic dose of digitalis. The authors believe that this is evidence that the change in blood flow was a result of peripheral and not of cardiac actions of the drug. Following a single therapeutic intravenous dose of digitalis, there was a gradual rise of blood pressure, sometimes sustained during several hours in anima.ls which had not been operated on, and simultaneously there were constriction of the vessels of the skin a.nd intestine and an increase in the volume of the liver and spleen due to hcpatic vein constriction and to a pooling of blood in these viseera. These changes must have resulted in the diminished venous return to the heart and a diminished output and heart size. The authors believe that these facts are in agreement with the generally accepted view that the output of the normal heart is governed largely by the venous return. The work of previous investigators has shown that the heart contracts with increased efficiency after therapeutic doses of digitalis but that the effect on cardiac output varies with the functional state of the circulation. The action of the drug in man probably varies in the same way; i.e., the output of the normal heart is reduced, but in such pathological states as heart failure with passive hyperemia, digitalis would tend to increase the cardiac output and to restore the venous pressure to a normal level.
on the Uirculatory Actions Tainter, M. L., and Dock, W.: Further Observations of Digitalis and Strophanthus With Special Reference to the Liver, and Comparisons With H&amine and Epinephrine. J. Clin. Investigation 8: 485, 1930. When dogs are given by intravenous injection doses of digitalis corresponding to the full therapeutic dose for man, they exhibit a rise in arterial and fall in right These changes auricular pressure but a simultaneous rise in portal vein pressure. The fall in systemic ma the rise in portal vein are also caused by strophanthus. pressure are due to constriction of hepatic veins. After the liver was eliminated from the circulation by shunting the portal blood directly into the inferior vena eava or by ligating the arteries which supply the splanchnic area, digitalis or strophanthus did not cause a fall in venous pressure but in several instances raised it and did not cause as marked an elevation of arterial pressure as in the animals Therefore, the fall in right auricular with the splanchnic circulation intact. pressure, after giving digitalis to dogs with the hepatic circulation intact, was due to diminished venous return flow and ultimately to an accumulation of blood in the splanchnic or portal region as a result of obstructed hepatic outflow. The experimental procedures used to determine the actions of digitalis and strophanthus were controlled by comparisons in the same organism with known
THE
AMERICAN
HEART
JOURNAL
The results show that during aortic insufficiency the diastolic size is larger and the left ventricular discharge is increased from 16 to SS prr cent in different cspcri mcnts, on an average 36.4 per cent. Factors cjthrr than heart rato and sizr of leak are responsible for the variations. In the discussion it is pointed out that changes in heart size without data concerning the stroke volumes of the left ventricle are of no value in determining the percentile regurgitation, but that the percentile changes in st,roke volume of the left ventricle give by inference a fair estimate of the percentile regurgitation. The conclusion is reached that approximately one-third of the discharge during systole regurgitates through insufficient valves during diastole.
Dock, W., and Tainter, M. L.: The Circulatory Changes After Full Therapeutic Doses of Digitalis, With a Critical Discussion of Views on Cardiac Output. J.
Clin.
Investigation
8:
467,
1930.
Under experimental conditions in dogs a fall of venous pressure regularly accompanied the diminished cardiac output following a full therapeutic dose of digitalis. The authors believe that this is evidence that the change in blood flow was a result of peripheral and not of cardiac actions of the drug. Following a single therapeutic intravenous dose of digitalis, there was a gradual rise of blood pressure, sometimes sustained during several hours in anima.ls which had not been operated on, and simultaneously there were constriction of the vessels of the skin a.nd intestine and an increase in the volume of the liver and spleen due to hcpatic vein constriction and to a pooling of blood in these viseera. These changes must have resulted in the diminished venous return to the heart and a diminished output and heart size. The authors believe that these facts are in agreement with the generally accepted view that the output of the normal heart is governed largely by the venous return. The work of previous investigators has shown that the heart contracts with increased efficiency after therapeutic doses of digitalis but that the effect on cardiac output varies with the functional state of the circulation. The action of the drug in man probably varies in the same way; i.e., the output of the normal heart is reduced, but in such pathological states as heart failure with passive hyperemia, digitalis would tend to increase the cardiac output and to restore the venous pressure to a normal level.
on the Uirculatory Actions Tainter, M. L., and Dock, W.: Further Observations of Digitalis and Strophanthus With Special Reference to the Liver, and Comparisons With H&amine and Epinephrine. J. Clin. Investigation 8: 485, 1930. When dogs are given by intravenous injection doses of digitalis corresponding to the full therapeutic dose for man, they exhibit a rise in arterial and fall in right These changes auricular pressure but a simultaneous rise in portal vein pressure. The fall in systemic ma the rise in portal vein are also caused by strophanthus. pressure are due to constriction of hepatic veins. After the liver was eliminated from the circulation by shunting the portal blood directly into the inferior vena eava or by ligating the arteries which supply the splanchnic area, digitalis or strophanthus did not cause a fall in venous pressure but in several instances raised it and did not cause as marked an elevation of arterial pressure as in the animals Therefore, the fall in right auricular with the splanchnic circulation intact. pressure, after giving digitalis to dogs with the hepatic circulation intact, was due to diminished venous return flow and ultimately to an accumulation of blood in the splanchnic or portal region as a result of obstructed hepatic outflow. The experimental procedures used to determine the actions of digitalis and strophanthus were controlled by comparisons in the same organism with known