Reflections on systolic and diastolic augmentation

An analog model is developed to characterize how alterations of some intra-aortic balloon pump (IABP) parameters affect the coupling between left ventricle (LV) and aorta. The time-varying elastance concept is applied to modeling both active components (LV and IABP) in the assisted circulation. Pressure and flow waveforms in the system are determined by numerically integrating five simultaneous state equations that represent the system dynamics. Validity of the model is supported by good agreement between model predictions and published data on LV pressure-volume (P-V) loops, end-systolic P-V relations, and hemodynamic consequences of adjusting IABP timing and speed. The model also predicts that increasing balloon volume increases the diastolic aortic pressure augmentation but has a negative effect of increasing LV load. Increasing balloon diameter over length ratio and holding a constant volume increases the diastolic augmentation and decreases the LV demand. Positioning the balloon closer to the heart improves systolic unloading but affects neither diastolic augmentation nor cardiac output. These results suggest that occlusivity is a major determinant of IABP effectiveness and plays a more important role than balloon volume and position.

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Current status of diastolic augmentation for circulatory support

American Heart Journal ◽

10.1016/0002-8703(71)90141-4 ◽

1971 ◽

Vol 81 (2) ◽

pp. 281-287 ◽

Cited By ~ 2

Author(s):

Leslie A. Kuhn

Keyword(s):

Current Status ◽

Circulatory Support ◽

Diastolic Augmentation

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Development of a Pulsatile Flow-Generating Circulatory Assist Device (K-Beat) for Use with Veno-Arterial Extracorporeal Membrane Oxygenation in a Pig Model Study

Biology ◽

10.3390/biology9060121 ◽

2020 ◽

Vol 9 (6) ◽

pp. 121

Author(s):

Yutaka Fujii ◽

Nobuo Akamatsu ◽

Yasunori Yamasaki ◽

Kota Miki ◽

Masayuki Banno ◽

...

Keyword(s):

Heart Failure ◽

Extracorporeal Membrane Oxygenation ◽

Pulsatile Flow ◽

Circulatory Support ◽

Large Animal ◽

Assist Device ◽

Membrane Oxygenation ◽

First Choice ◽

Circulatory Flow ◽

Diastolic Augmentation

Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) preserves the life of heart failure patients by providing an adequate oxygen supply and blood flow to vital organs. For patients with severe cardiogenic shock secondary to acute myocardial infarction or acute myocarditis, V-A ECMO is commonly used as the first choice among cardiac circulatory support devices. While V-A ECMO generates circulatory flow using a centrifugal pump, the provision of pulsatile flow is difficult. We previously reported our development of a new circulatory flow assist device (K-beat) for cardiac management with pulsatile flow. To obtain more efficient pulsatile assist flow (diastolic augmentation), an electrocardiogram (ECG)-analyzing device that can detect R waves and T waves increases the assist flow selectively in the diastole phase by controlling (opening and closing) the magnetic valve of the tamper. Here, we describe the first use of the K-beat on a large animal in combination with a clinical device. In addition, the diastolic augmentation effect of the K-beat as a circulatory flow assist device was examined in a pig V-A ECMO model. The K-beat was stopped every 60 min for a period of a few minutes, and blood pressure waveforms in the pulsatile and non-pulsatile phases were checked. This experiment showed that stable V-A ECMO could be achieved and that hemodynamics were managed in all animals. The pulsatile flow was provided in synchrony with the ECG in all cases. A diastolic augmentation waveform of femoral arterial pressure was confirmed in the pulsatile phase. K-beat could be useful in patients with severe heart failure.

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RADIAL DIASTOLIC AUGMENTATION INDEX IS A USEFUL PREDICTOR OF ARTERIAL STIFFNESS

Journal of Mechanics in Medicine and Biology ◽

10.1142/s0219519412004405 ◽

2012 ◽

Vol 12 (01) ◽

pp. 1250011 ◽

Cited By ~ 2

Author(s):

YING-YING ZHENG ◽

CHI-WEN LUNG ◽

YONG-LIANG ZHANG ◽

XUE-QING LI ◽

ZU-CHANG MA ◽

...

Keyword(s):

Arterial Stiffness ◽

Healthy Subjects ◽

Augmentation Index ◽

Pressure Waveform ◽

Vascular Aging ◽

Anthropometric Parameters ◽

Follow Up Study ◽

Radial Artery Pressure ◽

Diastolic Augmentation

Diastolic augmentation index (DAI), calculated from radial artery pressure waveform, has been associated with the risk of cardiovascular disease. In the present study, we aimed to evaluate whether DAI could be used as a predictor of arterial stiffness and the effect of heart rate (HR) on it. Measurements of anthropometric parameters, blood pressure (BP), Augmentation index (AI) and DAI were taken in 242 healthy subjects (130 men and 112 women; age 16–78 years). DAI and AI were measured in a subgroup of 16 subjects (10 men and 6 women; age 19–69 years) in a two-month follow-up study, which aimed to investigate the effect of HR changes. Statistically, DAI was higher in women compared to men (44.8% ± 7.7% compared with 43.6% ± 6.9%, P < 0.05). DAI was decreased with age (men: r = -0.755, P < 0.05; women: r = -0.708, P < 0.05) and negatively correlated to AI (men: r = -0.704, P < 0.05; women: r = -0.756, P < 0.05). There was no significant change in DAI when HR ranged from 60 to 80 bpm. Multiple regression analysis demonstrated fewer determinants affect DAI compared with AI. These findings indicate that the simple radial DAI might be used as an index to assess vascular aging.

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