Effects of arterial input impedance on mean ventricular pressure-flow relation

1984 ◽  
Vol 247 (6) ◽  
pp. H978-H983 ◽  
Author(s):  
W. L. Maughan ◽  
K. Sunagawa ◽  
K. Sagawa
Keyword(s):  
Characteristic Impedance ◽  
Peripheral Resistance ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Pressure Flow ◽  
Inotropic State ◽  
End Diastolic Volume ◽  
State Compliance ◽  
Slope Change

The mean left ventricular pressure-flow relationship (Pv-Fv), determined under a constant preload and variable peripheral resistance, has been proposed as a quantitative representation of ventricular pump function (9). We determined the Pv-Fv relation in seven isolated cross-perfused canine hearts by varying resistance of a simulated arterial load in five steps from 6.0 to 0.375 mmHg X s X ml-1 while keeping end-diastolic volume, inotropic state, compliance, and characteristic impedance at various constant values. All of the 27 Pv-Fv relations thus determined were moderately nonlinear. Varying end-diastolic volume at three levels shifted the relation curve in an approximately parallel fashion (P less than 0.0001). At three levels of inotropic state (mean LVP of isovolumic contractions 34.3 +/- 8.2, 48.0 +/- 6.3, and 59.2 +/- 9.6 mmHg), the Pv-Fv relation shifted with predominantly a slope change (P less than 0.0001). Changing compliance at three levels (0.2, 0.4, and 0.8 ml/mmHg) caused a statistically significant but quantitatively small crossover of the Pv-Fv curves (P less than 0.0001). Changing characteristic impedance to 0.1, 0.2, and 0.4 mmHg X s X ml-1 caused a highly significant (P less than 0.0001) divergence of Pv-Fv relation over the high Fv range. We conclude that this sensitivity of the Pv-Fv relation to characteristic impedance limits its use as a contractility index.

In vivo murine left ventricular pressure-volume relations by miniaturized conductance micromanometry

1998 ◽  
Vol 274 (4) ◽  
pp. H1416-H1422 ◽  
Author(s):  
Dimitrios Georgakopoulos ◽  
Wayne A. Mitzner ◽  
Chen-Huan Chen ◽  
Barry J. Byrne ◽  
Huntly D. Millar ◽  
...  
Keyword(s):  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Genetically Engineered ◽  
Ventricular Pressure ◽  
Stroke Work ◽  
Time Varying ◽  
End Diastolic Volume ◽  
Novel Approach ◽  
Preload Reduction

The mouse is the species of choice for creating genetically engineered models of human disease. To study detailed systolic and diastolic left ventricular (LV) chamber mechanics in mice in vivo, we developed a miniaturized conductance-manometer system. α-Chloralose-urethan-anesthetized animals were instrumented with a two-electrode pressure-volume catheter advanced via the LV apex to the aortic root. Custom electronics provided time-varying conductances related to cavity volume. Baseline hemodynamics were similar to values in conscious animals: 634 ± 14 beats/min, 112 ± 4 mmHg, 5.3 ± 0.8 mmHg, and 11,777 ± 732 mmHg/s for heart rate, end-systolic and end-diastolic pressures, and maximum first derivative of ventricular pressure with respect to time (dP/d t max), respectively. Catheter stroke volume during preload reduction by inferior vena caval occlusion correlated with that by ultrasound aortic flow probe ( r 2 = 0.98). This maneuver yielded end-systolic elastances of 79 ± 21 mmHg/μl, preload-recruitable stroke work of 82 ± 5.6 mmHg, and slope of dP/d t max-end-diastolic volume relation of 699 ± 100 mmHg ⋅ s−1 ⋅ μl−1, and these relations varied predictably with acute inotropic interventions. The control normalized time-varying elastance curve was similar to human data, further supporting comparable chamber mechanics between species. This novel approach should greatly help assess cardiovascular function in the blood-perfused murine heart.

End-systolic stress-velocity and pressure-dimension relationships by transthoracic echocardiography in mice

1998 ◽  
Vol 274 (5) ◽  
pp. H1828-H1835 ◽  
Author(s):  
Richard V. Williams ◽  
John N. Lorenz ◽  
Sandra A. Witt ◽  
David T. Hellard ◽  
Philip R. Khoury ◽  
...  
Keyword(s):  
Transthoracic Echocardiography ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Intact Mouse ◽  
Pressure Recording ◽  
Pressure Load ◽  
Inotropic State ◽  
Velocity Relationship ◽  
Ejection Phase

The purposes of this study were to assess load-independent, end-systolic relationships in mice and compare these relationships to ejection phase indexes in assessing contractility. In 13 mice, ejection phase indexes (shortening fraction and velocity of fiber shortening) and end-systolic relationships [pressure-dimension relationship (ESPDR) and stress-velocity relationship (ESSVR)] were determined using M-mode echocardiography and simultaneous left ventricular pressure. Load was altered with phenylephrine and nitroprusside. Contractility was increased with dobutamine and decreased by induction of hypothyroidism. Ejection phase indexes increased with dobutamine infusion but were not significantly decreased with hypothyroidism. However, end-systolic relationships changed significantly with both dobutamine ( y-intercepts: ESPDR from 22 to 48 mmHg, ESSVR from 3.7 to 6.6 circ/s, P < 0.05) and hypothyroidism ( y-intercepts: ESPDR from 22 to 11 mmHg, ESSVR from 3.7 to 3.2 circ/s, P< 0.05). We conclude that end-systolic indexes can be accurately measured in the intact mouse by echocardiography with simultaneous left ventricular pressure recording and appear to be more sensitive to inotropic state than ejection phase indexes.

Effects of regional ischemia and ventricular pacing on LV dP/dtmax-end-diastolic volume relation

1987 ◽  
Vol 252 (5) ◽  
pp. H933-H940 ◽  
Author(s):  
W. C. Little ◽  
R. C. Park ◽  
G. L. Freeman
Keyword(s):  
Coronary Artery ◽  
Right Ventricular ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Free Wall ◽  
Ventricular Pressure ◽  
Free Wall ◽  
Ventricular Pacing ◽  
End Diastolic Volume ◽  
The Right

We investigated the effects of coronary artery occlusion and pacing from ventricular sites on the relation of the maximum rate of rise of left ventricular pressure (dP/dtmax) to the end-diastolic volume (VED) in dogs previously instrumented to measure left ventricular pressure and to determine left ventricular volume from three ultrasonically measured dimensions. The dP/dtmax-VED relation was generated by vena caval occlusion and compared with the simultaneously produced end-systolic pressure-end-systolic volume (PES-VES) relation. The dP/dtmax-VED relation was described by a straight line during all conditions. Occlusion of the left circumflex coronary artery produced a rightward shift of the dP/dtmax-VED relation, increasing the volume intercept by 11.3 +/- 5.3 (SD) ml (P less than 0.05). Compared with atrial pacing, the dP/dtmax-VED relation was shifted to the right with the volume intercept increasing by 4.8 +/- 4.4 ml (P less than 0.05) during pacing from the right ventricular free wall, 3.7 +/- 5.0 ml (P less than 0.05) during pacing from the right ventricular apex, and 3.7 +/- 2.4 ml (P less than 0.05) during pacing from the left ventricular free wall. Similar increases were observed in the volume intercepts of the PES-VES relations during coronary occlusion or ventricular pacing. These results are consistent with the predictions of the time-varying elastance model and support its use as a conceptual framework to understand left ventricular performance during isovolumic contraction and at end systole, both in the normal ventricle and the ventricle with regional abnormalities of contraction.

Effects of reduced resistive afterload on left ventricular pressure-volume relationship

1985 ◽  
Vol 248 (2) ◽  
pp. H163-H169
Author(s):  
J. Ducas ◽  
U. Schick ◽  
L. Girling ◽  
R. M. Prewitt
Keyword(s):  
Systolic Pressure ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Ventricular Pressure ◽  
Base Line ◽  
Resistive Load ◽  
Systolic Volume ◽  
Arteriovenous Fistulas ◽  
End Diastolic Volume ◽  
End Systolic Volume

In seven anesthetized, beta-blocked dogs, we investigated the effects of a reduction in systemic vascular resistance (SVR) on left ventricular (LV) systolic mechanics. LV pressure and volumes (scintigraphic techniques) were measured in base-line condition, after opening one and then two arteriovenous fistulas (AVF). Volume was infused to maintain LV end-systolic pressure (LVESP). Despite a constant ESP, the mean end-systolic volume (LVESV) fell from 42 to 31 ml (P less than 0.025) when the SVR fell from 81 to 48 units (P less than 0.0025), and the LVESV fell further to 24 ml (P less than 0.0025) when the SVR was decreased to 30 units (P less than 0.025). In six similarly prepared dogs, aortic flow was measured, and when resistive afterload decreased, instantaneous flow increased. Since end-diastolic volume was not significantly changed when resistive afterload decreased, instantaneous LV volume decreased despite constant systolic LV pressure. In two of these dogs, LV pressure-volume (PV) trajectories were drawn for the ejection period. When SVR decreased there was a marked leftward shift of the PV trajectory as the end of ejection was approached. It is concluded that at a given contractile state and ventricular pressure, alterations in resistive load directly affect rate and extent of ventricular shortening.

Evidence and quantitation of left ventricular systolic resistance

1985 ◽  
Vol 249 (2) ◽  
pp. H358-H370 ◽  
Author(s):  
S. G. Shroff ◽  
J. S. Janicki ◽  
K. T. Weber
Keyword(s):  
Quantitative Description ◽  
Systolic Pressure ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Arterial System ◽  
Ventricular Pressure ◽  
Elastic Behavior ◽  
Volume Data ◽  
Ventricular Performance ◽  
Pressure Flow

Instantaneous left ventricular pressure is a function of both volume (elastic behavior) and flow (resistive behavior). However, a quantitative description of ventricular resistance and its effects on ventricular performance remains to be elucidated. Accordingly, ventricular resistive behavior was studied in six isolated canine hearts. Our experimental findings indicate 1) for a specified time (ts), volume (Vs), and contractile state (CS), the ventricular pressure-flow relation was linear (r = 0.96-0.99) within the range of flows examined (0-250 ml/s); 2) ventricular resistance increased with increments in ts, Vs, and CS, whereas the zero-pressure flow intercept was invariant; 3) resistance could be uniquely quantified as a linear function of isovolumetric pressure. In six experiments, the slope of this relationship ranged from 1.1 to 2.1 X 10(-3) s/ml while the intercept did not differ from zero; and 4) end-systolic elastance, estimated from end-systolic pressure-volume data, was in substantial error under the conditions of finite (greater than 35 ml/s) end-systolic flows. Finally, the results from a computer simulation of the coupled ventricular-arterial system indicated that ventricular resistance primarily affects the pulsatile nature of aortic flow. The unique isovolumetric pressure-resistance relation suggests that the rate-limiting properties of the contractile process may be causally related to the observed ventricular resistive behavior.

scholarly journals Left ventricular pressure-volume relationship in a rat model of advanced aging-associated heart failure

2004 ◽  
Vol 287 (5) ◽  
pp. H2132-H2137 ◽  
Author(s):  
Pál Pacher ◽  
Jon G. Mabley ◽  
Lucas Liaudet ◽  
Oleg V. Evgenov ◽  
Anita Marton ◽  
...  
Keyword(s):  
Diastolic Pressure ◽  
Systolic Pressure ◽  
Left Ventricular Pressure ◽  
Left Ventricular ◽  
Male Rats ◽  
Ventricular Pressure ◽  
Stroke Work ◽  
Effective Prevention ◽  
Fischer 344 ◽  
End Diastolic Volume

Aging is associated with profound changes in the structure and function of the heart. A fundamental understanding of these processes, using relevant animal models, is required for effective prevention and treatment of cardiovascular disease in the elderly. Here, we studied cardiac performance in 4- to 5-mo-old (young) and 24- to 26-mo-old (old) Fischer 344 male rats using the Millar pressure-volume (P-V) conductance catheter system. We evaluated systolic and diastolic function in vivo at different preloads, including preload recruitable stroke work (PRSW), maximal slope of the systolic pressure increment (+dP/d t), and its relation to end-diastolic volume (+dP/d t-EDV) as well as the time constant of left ventricular pressure decay, as an index of relaxation. The slope of the end-diastolic P-V relation (EDPVR), an index of left ventricular stiffness, was also calculated. Aging was associated with decrease in left ventricular systolic pressure, +dP/d t, maximal slope of the diastolic pressure decrement, +dP/d t-EDV, PRSW, ejection fraction, stroke volume, cardiac and stroke work indexes, and efficiency. In contrast, total peripheral resistance, left ventricular end-diastolic volume, left ventricular end-diastolic pressure, and EDPVR were greater in aging than in young animals. Taken together, these data suggest that advanced aging is characterized by decreased systolic performance accompanied by delayed relaxation and increased diastolic stiffness of the heart in male Fischer 344 rats. P-V analysis is a sensitive method to determine cardiac function in rats.

Sign in / Sign up

Export Citation Format

Share Document