Reference sites not influenced by hydrostatic pressure for right and left atrial pressures

1964 ◽  
Vol 207 (2) ◽  
pp. 357-360 ◽  
Author(s):  
George G. Armstrong ◽  
John C. Hancock
Keyword(s):  
Hydrostatic Pressure ◽  
Reference Point ◽  
Left Atrial ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Right Atrial ◽  
Lateral Border ◽  
Zero Reference ◽  
The Right ◽  
Made In

Simultaneous recordings of left and right atrial pressures made in dogs being rotated into all positions in space allowed the location of rotational axes where right or left atrial pressure became independent of hydrostatic pressure. Utilization of these axes as zero reference levels made possible the measurement of right or left atrial pressure without the influence of hydrostatic factors. The right zero reference point lay 62.8% of the distance from the manubrium to the xiphoid, 61.2% of the posterior to anterior thoracic diameter, and 47.7% of the greatest transverse thoracic diameter as measured from the right lateral border. The left atrial zero reference point lay 62.1% of the manubrium to xiphoid distance, 57.2% of the posterior to anterior diameter of thorax, and 53.0% of the greatest transverse thoracic diameter as measured from the right lateral border. When referred to the anatomy of the dog, these points lay in the immediate vicinity of the right and left atrioventricular valves, respectively.

Control of atrial natriuretic factor by right and left atrial distension in pregnant sheep

1995 ◽  
Vol 268 (6) ◽  
pp. R1411-R1417
Author(s):  
D. Javeshghani ◽  
S. Mukaddam-Daher ◽  
L. Fan ◽  
Z. Guan ◽  
J. Gutkowska ◽  
...  
Keyword(s):  
Atrial Natriuretic Factor ◽  
Left Atrial ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Natriuretic Factor ◽  
Pregnant Sheep ◽  
Vascular Catheters ◽  
The Right ◽  
Left Atrial Distension ◽  
Atrial Natriuretic

Previous studies of the atrial stretch-atrial natriuretic factor (ANF) relationship during pregnancy have employed volume expansion and measured only right atrial pressure (RAP). Consequently, we studied nonpregnant (n = 7) and 115- to 125-day pregnant (n = 7) sheep and assessed the ANF response to changes of RAP and left atrial pressure (LAP) induced by graded balloon inflation. Ewes prepared with vascular catheters and atrial balloons were studied after recovery from preparatory surgical procedures. The basal levels of mean arterial pressure (MAP, 83 +/- 3 mmHg), RAP (2.1 +/- 0.7 mmHg), LAP (4.7 +/- 0.9 mmHg), and heart rate (HR, 102 +/- 6 beats/min) were similar in nonpregnant and pregnant sheep. Pregnancy also resulted in elevation of ANF concentration from 25 +/- 6 to 57 +/- 4 fmol/ml. With right atrial distension, the RAP-ANF relationships were similar in both nonpregnant and pregnant sheep, with a 10-mmHg increase in RAP increasing ANF by an average of 95 +/- 9 fmol/ml. In nonpregnant sheep, the LAP-ANF relationship was more responsive than RAP-ANF because a 10-mmHg increase in LAP resulted in a 193 +/- 10 fmol/ml increase in ANF. Moreover, during pregnancy, the LAP-ANF relationship was significantly more sensitive because a 10-mmHg increase in LAP resulted in a 433 +/- 15 fmol/ml elevation of ANF. These data demonstrate that plasma ANF levels are more responsive to distension of the left atria than to the right. More importantly, the ANF response to left, but not right, atrial distension is enhanced by pregnancy.

Reflex effects of left atrial pressure elevation on total intravascular volume

1981 ◽  
Vol 241 (5) ◽  
pp. H760-H765 ◽  
Author(s):  
D. L. Rutlen
Keyword(s):  
Left Atrial ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Intravascular Volume ◽  
Pressure Elevation ◽  
Reservoir Volume ◽  
Baroreceptor Stimulation ◽  
Mitral Orifice ◽  
Autonomic Reflex ◽  
The Right

The reflex autonomic influence of left atrial baroreceptor stimulation on the total capacitance vasculature has not been examined. To this end, left atrial pressure was increased in 25 anesthetized dogs, in which blood from the vena cavae was drained into an extracorporeal reservoir and returned to the right atrium at a constant rate, so that changes in intravascular volume could be recorded as reciprocal changes in reservoir volume. Left atrial pressure was elevated from 5 +/- 1 (mean +/- SE) to 11 +/- 1 mmHg by inflating a balloon at the mitral orifice for 12-20 min. With left atrial pressure elevation, total intravascular volume decreased 25 +/- 10 ml (P less than 0.025). In six of the dogs, intravascular volume decreased 37 +/- 12 ml with left atrial pressure elevation before bilateral cervical vagectomies and increased 66 +/- 8 ml with atrial pressure elevation after vagectomies (P less than 0.001). In eight of the dogs, volume decreased 42 +/- 19 ml with atrial pressure elevation before propranolol administration and increased 44 +/- 29 ml after propranolol (P less than 0.03). Phenoxybenzamine in five of the animals and atropine in three did not attenuate the change in intravascular volume with left atrial pressure elevation. Thus left atrial baroreceptor stimulation is associated with an autonomic reflex, which acts to decrease intravascular volume. The afferent limb is mediated by the vagi, and the efferent limb, by beta-adrenergic receptor stimulation.

Progressive changes in cardiovascular function after unilateral heart irradiation

1964 ◽  
Vol 206 (2) ◽  
pp. 289-293 ◽  
Author(s):  
H. L. Stone ◽  
V. S. Bishop ◽  
A. C. Guyton
Keyword(s):  
Left Ventricle ◽  
Arterial Pressure ◽  
Blood Volume ◽  
Pulse Rate ◽  
Left Atrial ◽  
Pressure Pulse ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Before And After ◽  
The Right

Chronic heart failure was produced by giving 20,000 r Co60 irradiation to either the right or left ventricle in nine closed-chest animals. Measurements of right and left atrial pressures, arterial pressure, pulse rate, body weight, and blood volume were made before and after irradiation. The right and left atrial pressures rose progressively until death in three animals irradiated on the right side. In six animals irradiated on the left side, the left atrial pressure rose progressively, but the right atrial pressure either did not rise or rose only during the latter stages of failure. Declining arterial pressure and increasing pulse rate were common to both groups. Increases in blood volume were observed in all animals, but this increase was only significant in the group irradiated on the left side. At autopsy, 70–100% of the right ventricular muscle was damaged in dogs irradiated on the right side, and 40–70% of the left ventricle in dogs irradiated on the left side. Hydrothorax and liver congestion were found in the right-sided group and pulmonary congestion in the left-sided group.

Effect of diaphragm contraction on canine heart and pericardium

1983 ◽  
Vol 54 (5) ◽  
pp. 1261-1268 ◽  
Author(s):  
T. C. Lloyd ◽  
J. A. Cooper
Keyword(s):  
Cardiac Output ◽  
Left Atrial ◽  
Servo Control ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Right Atrial ◽  
Right Atrial Pressure ◽  
Abdominal Pressure ◽  
Canine Heart ◽  
Pressure Changes

Pericardiophrenic attachments transmit diaphragm contraction to the pericardium. We investigated this in two ways. 1) We replaced the hearts of externally perfused dogs with a balloon from which we measured pressure changes. Diaphragm contraction increased pressure from 4.6 to 5.5 Torr, equivalent to an isobaric volume decrease of 1.5%, and decreased volumetric compliance by 3%. 2) We selectively servo controlled right atrial pressure, left atrial pressure, or cardiac output in open-chest dogs and monitored the effect of diaphragm contraction on cardiovascular and abdominal pressures, cardiac output, and the volume of blood added to or withdrawn from the circulation to achieve servo control. Diaphragm contraction decreased left atrial pressure 0.4 Torr when right atrial pressure was controlled and right atrial pressure increased 0.2 Torr while controlling left atrial pressure, but there were no significant changes in cardiac output. Atrial pressure did not change significantly when output was controlled. Servo control required removal of approximately 50 ml of blood, presumably reflecting a decreased splanchnic vascular capacity at the higher abdominal pressure. We conclude that the diaphragm may slightly tense the pericardium, but this has no important primary effect on the heart.

Elevated cardiac pressure inhibits renin release after arterial hypotension in conscious dogs

1984 ◽  
Vol 247 (6) ◽  
pp. R953-R959 ◽  
Author(s):  
M. E. Lee ◽  
T. N. Thrasher ◽  
D. J. Ramsay
Keyword(s):  
Left Atrial ◽  
Dose Range ◽  
Plasma Renin ◽  
Ascending Aorta ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Renin Release ◽  
Right Atrial ◽  
Apparent Paradox ◽  
Systemic Hypotension

The relative roles of cardiopulmonary, sinoaortic, and renal baroreceptors in the regulation of plasma renin activity (PRA) were evaluated in dogs with chronically implanted cuffs around the ascending aorta proximal to the brachiocephalic artery, the abdominal aorta just proximal to both renal arteries, or both. Inflation of either cuff was adjusted to cause a reduction of distal arterial pressure and hence renal perfusion pressure (RPP) of 0, 5, 10, 20, or 30% of control for 1 h. Reduction of RPP by inflation of the suprarenal cuff (n = 4) led to a significant (P less than 0.05) increase in PRA throughout the dose range examined. However, constriction of the ascending aorta (n = 7) to cause identical reductions in RPP failed to increase PRA. The apparent paradox in these results may be explained by differential effects of the two maneuvers on left atrial pressure. Left atrial pressure increased dose dependently during inflation of the ascending aortic cuff but did not change during inflation of the suprarenal cuff. To determine if elevated right atrial pressure (RAP) would inhibit renin release after systemic hypotension, another group of dogs (n = 4) was prepared with cuffs around the pulmonary artery. Inflation of the pulmonary cuff to cause similar systemic hypotension led to significant (P less than 0.05) increases in PRA and RAP. Therefore we conclude that powerful inhibitory signals, arising from the left heart, can inhibit renin release in response to systemic hypotension.

Cardiovascular effects of increasing airway pressure in the dog

1977 ◽  
Vol 232 (1) ◽  
pp. H35-H43 ◽  
Author(s):  
S. M. Scharf ◽  
P. Caldini ◽  
R. H. Ingram
Keyword(s):  
Lung Volume ◽  
Airway Pressure ◽  
Left Atrial ◽  
Venous Return ◽  
Pressure Rise ◽  
Cardiovascular Effects ◽  
Atrial Pressure ◽  
Pleural Pressure ◽  
Left Atrial Pressure ◽  
Right Atrial

In paralyzed anesthetized dogs the cardiovascular effects of increasing positive end-expiratory pressure (PEEP) were explored under two conditions: a) end-expiratory lung volume increasing, b) end-expiratory lung volume kept nearly constant by matching pleural pressure rise to end-expiratory airway pressure rise. Two series of experiments were done: I) xenous return was allowed to fall, II) venous return was kept constant by infusion of volume. Right atrial pressure, pulmonary arterial pressure, and left atrial pressure increased under all conditions when measured relative to atmospheric pressure, but increased relative to pleural pressure only under condition a. The rise in left atrial relative to pleural pressure may indicate a degree of left ventricular dysfunction associated with increasing end-expiratory lung volume. Furthermore, when end-expiratory lung volume increased, inequality of the rise in pulmonary artery wedge pressure exceeded the rise in left atrial pressure in series I. From plots of cardiac output as a function of right atrial pressure it was possible to conclude that the decrease in venous return is partially offset by an increase in mean circulatory pressure.

Action of Digitalis on the Nonfailing Heart of the Dog

1957 ◽  
Vol 192 (1) ◽  
pp. 114-120 ◽  
Author(s):  
Marion deV. Cotten ◽  
Phyllis E. Stopp
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Left Atrial ◽  
Venous Return ◽  
Contractile Force ◽  
Left Ventricular ◽  
Atrial Pressure ◽  
Left Atrial Pressure ◽  
Right Atrial ◽  
Stroke Work

Ouabain induces a moderate increase in the contractility of the nonfailing heart of the dog with a complete circulatory system in doses which do not produce electrocardiographic signs of digitalis intoxication. The increased contractility was demonstrated both by the increase in ventricular contractile force and by the higher ventricular function curves obtained after administration of ouabain. The drug also increased systemic peripheral resistance and blood pressure, decreased systemic output, heart rate, left and right atrial pressures, and produced only small, variable changes in left ventricular stroke work. The reduction in systemic output and left atrial pressure and the absence of substantial changes in stroke work after ouabain appeared to be the result of a decrease in venous return to the heart. Evidence for this interpretation was obtained from experiments in which left atrial pressure was kept constant during the actions of ouabain by infusing 100–300 cc of whole blood. Under these conditions, ouabain brought about moderate increases in systemic output and left ventricular stroke work as well as in contractile force even though the changes in heart rate and blood pressure were comparable to those obtained in experiments in which left atrial pressure was uncontrolled. The data presented indicate that ouabain has two primary hemodynamic effects in the normal animal, namely, a direct cardiac stimulant action and a peripheral action resulting in a decreased venous return. The relationship of these findings to the mechanism of action of digitalis in congestive heart failure is discussed.

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