What question did this study set out to answer?

To determine whether changes in end-systolic volume or loading sequence drive the enhanced load sensitivity of left ventricular relaxation in failing hearts.

December 15, 1995Circulation

Loading Sequence Plays an Important Role in Enhanced Load Sensitivity of Left Ventricular Relaxation in Conscious Dogs With Tachycardia-Induced Cardiomyopathy

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Why the study?

Does loading sequence play a role in enhanced load sensitivity of left ventricular relaxation in conscious dogs with tachycardia-induced cardiomyopathy?

Key Points

To determine whether changes in end-systolic volume or loading sequence drive the enhanced load sensitivity of left ventricular relaxation in failing hearts.
Evaluated hemodynamics in seven conscious dogs (N=7) before and after rapid ventricular pacing induced cardiomyopathy.
Measured left ventricular pressure decay time constant (Td), end-systolic volume, systolic circumferential force, and time to peak force during transient vena caval occlusion.
Rapid pacing decreased the end-systolic pressure-volume relation slope from 4.5 to 2.8 mm Hg/mL (P < .01) and prolonged Td from 33 to 49 ms (P < .01).
During caval occlusion, Td decreased significantly in heart failure (-11 ms, P < .01) with a drop in time to peak force (-30 ms, P < .01), whereas normal hearts showed no significant change in Td despite reduced volume (-7 mL, P < .01) and force (-580 g, P < .01).
Changes in Td strongly correlated with shifts in time to peak force (r = .79, P < .01), but showed no correlation with end-systolic volume.

Structured PICO

Does loading sequence play a role in enhanced load sensitivity of left ventricular relaxation in conscious dogs with tachycardia-induced cardiomyopathy?

Population

7 conscious dogs with tachycardia-induced cardiomyopathy (heart failure)

Intervention

Caval occlusion

Comparator

Normal conditions (before development of tachycardia-induced heart failure) in the same dogs

Outcome

Time constant (Td) of left ventricular pressure decay, end-systolic volume, systolic circumferential force, and time to peak forcesurrogate

Loading sequence, rather than elastic recoil, plays the predominant role in the enhanced load sensitivity of left ventricular relaxation in heart failure.

Discussion

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Implication

Supports loading sequence over recoil in HF relaxation sensitivity; hypothesis-generating for human load studies.

Cite This Study

Ishizaka et al. (1995) studied this question.

synapsesocial.com/papers/6a6f49c4e71d69abee07f0d0 https://doi.org/10.1161/01.cir.92.12.3560

Topics

Heart failure Ventricular arrhythmias HFrEF treatment

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Loading Sequence Plays an Important Role in Enhanced Load Sensitivity of Left Ventricular Relaxation in Conscious Dogs With Tachycardia-Induced Cardiomyopathy

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Topics

Loading Sequence Plays an Important Role in Enhanced Load Sensitivity of Left Ventricular Relaxation in Conscious Dogs With Tachycardia-Induced Cardiomyopathy

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Also Consider

Topics

Also Consider