What question did this study set out to answer?

To determine how changes in the sequence and timing of systolic aortic loading affect aortic end-systolic pressure and left ventricular isovolumic relaxation.

June 1, 1996Circulation

Change in Aortic End-Systolic Pressure by Alterations in Loading Sequence and Its Relation to Left Ventricular Isovolumic Relaxation

Q: What is the clinical evidence from this study?

Study design: Other. Population: Anesthetized dogs (n=7). Intervention: Constriction of descending and ascending aortas vs. Baseline / ascending vs descending intervention. Primary outcome: Left ventricular relaxation (time constant [T]) and aortic end-systolic pressure (p=<.05).

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Key result

Descending aortic constriction induced greater prolongation of the left ventricular relaxation time constant than ascending constriction (P < .05).

Population

Seven anesthetized dogs

Comparison

Constriction of the descending aorta to elevate… vs Constriction of the ascending aorta

Design

Preclinical

Authors

FKFujimasa KohnoKyoto University TKToshiaki KumadaNational Institute of Advanced Industrial Science and Technology MKMasashi KambayashiUniversity of California San Diego Medical Center

Discussion

Member takes

Implication

Does not yet warrant changes in clinical afterload assessment; extends preclinical understanding of loading sequence effects on LV relaxation.

Key Points

To determine how changes in the sequence and timing of systolic aortic loading affect aortic end-systolic pressure and left ventricular isovolumic relaxation.
Conducted an interventional physiological experiment in seven anesthetized dogs (N=7).
Applied brief, sustained mechanical constrictions to both the ascending and descending aortas to increase left ventricular peak systolic pressure by approximately 40 mm Hg.
Descending aortic constriction elevated aortic end-systolic pressure from 110.4 ± 9.3 to 150.8 ± 11.5 mm Hg (P < .05) and prolonged the left ventricular relaxation time constant T from 31.9 ± 4.4 to 69.8 ± 12.8 ms (P < .05).
Ascending aortic constriction decreased aortic end-systolic pressure from 111.9 ± 11.4 to 101.5 ± 10.3 mm Hg (P < .05) and prolonged T to a lesser extent, from 31.2 ± 5.4 to 42.2 ± 8.3 ms (P < .05).
Prolongation of T was significantly greater during descending constriction compared to ascending constriction (P < .05), closely paralleling the increase in aortic end-systolic pressure.

Structured PICO

Population

Seven anesthetized dogs subjected to aortic constriction to evaluate left ventricular relaxation.

Intervention

Constriction of the descending aorta to elevate LV peak systolic pressure by approximately 40 mm Hg

Comparator

Constriction of the ascending aorta

Outcome

Left ventricular relaxation (time constant [T]) and aortic end-systolic pressure (AoESP)surrogate

Main Result

p-value: p=<.05

This preclinical study demonstrates that both the loading sequence and the pressure level at the onset of isovolumic relaxation determine left ventricular relaxation.

Cite This Study

Kohno et al. (1996) studied Anesthetized dogs (n=7). Constriction of descending and ascending aortas vs. Baseline / ascending vs descending intervention was evaluated on Left ventricular relaxation (time constant [T]) and aortic end-systolic pressure (p=<.05). Descending aortic constriction induced greater prolongation of the left ventricular relaxation time constant than ascending constriction (P < .05).

synapsesocial.com/papers/6a20051ed4e6d3589704cf54 https://doi.org/10.1161/01.cir.93.11.2080

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Implication

Does not yet warrant changes in clinical afterload assessment; extends preclinical understanding of loading sequence effects on LV relaxation.

Change in Aortic End-Systolic Pressure by Alterations in Loading Sequence and Its Relation to Left Ventricular Isovolumic Relaxation

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

Change in Aortic End-Systolic Pressure by Alterations in Loading Sequence and Its Relation to Left Ventricular Isovolumic Relaxation

Discussion

Member takes

Implication

Key Points

Structured PICO

Main Result

Cite This Study

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