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Alternative Approaches to the Assessment of the Systemic Circulation and Left Ventricular Performance: A Proof-of-Concept Study.

ABSTRACT: Background:The purpose of this article is to examine the systemic circulation and left ventricular (LV) performance by alternative, nonconventional approaches: systemic vascular conductance (G SV ) and the head-capacity relation (ie, the relation between LV pressure and cardiac output), respectively; in so doing, we aspired to present a novel and improved interpretation of integrated cardiovascular function. Methods:In 16 open-chest, anaesthetized pigs, we measured LV pressure (P LV ), central aortic pressure (P Ao ), and central venous pressure (P CV ) and aortic flow (Q Ao ). We calculated heart rate (HR), stroke volume, cardiac index (CI = cardiac output/body weight), mean PLV ( P¯LV) , and the average arteriovenous pressure difference ( ?P=P¯Ao-P¯CV ); G SV = CI/( P¯Ao-P¯CV ). We studied the effects of changing loading conditions with the administration of phenylephrine (? P¯Ao ? +25 mm Hg), isoproterenol (?HR ?+25%), sodium nitroprusside (? P¯Ao ? -25 mm Hg), and proximal aortic constriction (to maximize developed P LV and minimize Q Ao ). Results:Sodium nitroprusside and isoproterenol increased G SV compared with phenylephrine and constriction. A maximum head-capacity curve was derived from pooled data using nonlinear regression on the maximum P¯LV values in Q Ao bins 12.5 mL/min/kg wide. The head-capacity relation and the plots of conductance were combined using CI as a common axis, which illustrated that CI is the output of the heart and the input of the circulation. Conclusions:Thus, at a given CI, G SV determines the driving pressure and, thereby, P Ao . We also demonstrated how decreases in G SV compensate for arterial hypotension by restoring the arteriovenous pressure difference and arterial pressure.

SUBMITTER: Howell S

PROVIDER: S-EPMC7063645 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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Alternative Approaches to the Assessment of the Systemic Circulation and Left Ventricular Performance: A Proof-of-Concept Study.

Howell Sarah S Burrowes Lindsay M LM Belenkie Israel I Ter Keurs Henk E D J HEDJ Lei Lucy L Raj Satish R SR Bouwmeester J Christopher JC Sheldon Robert S RS Shrive Nigel G NG Tyberg John V JV

CJC open 20190213 2

<h4>Background</h4>The purpose of this article is to examine the systemic circulation and left ventricular (LV) performance by alternative, nonconventional approaches: systemic vascular conductance (<i>G</i> <sub><i>SV</i></sub> ) and the head-capacity relation (ie, the relation between LV pressure and cardiac output), respectively; in so doing, we aspired to present a novel and improved interpretation of integrated cardiovascular function.<h4>Methods</h4>In 16 open-chest, anaesthetized pigs, we ...[more]

PMID: 32159088

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Project description:IntroductionIn orbital reconstruction, the optimal location of a predefined implant can be planned preoperatively. Surgical results can be assessed intraoperatively or postoperatively. A novel method for quantifying orbital implant position is introduced. The method measures predictability of implant placement: transformation parameters between planned and resulting implant position are quantified.MethodsThe method was tested on 3 human specimen heads. Computed Tomography scans were acquired at baseline with intact orbits (t0), after creation of the defect (t1) and postoperatively after reconstruction of the defect using a preformed implant (t2). Prior to reconstruction, the optimal implant position was planned on the t0 and t1 scans. Postoperatively, the planned and realized implant position were compared. The t0 and t2 scans were fused using iPlan software and the resulting implant was segmented in the fused t2 scan. An implant reference frame was created (Orbital Implant Positioning Frame); the planned implant was transformed to the reference position using an Iterative Closest Point approach. The segmentation of the resulting implant was also registered on the reference position, yielding rotational (pitch, yaw, roll) as well as translational parameters of implant position.ResultsMeasurement with the Orbital Implant Positioning Frame proved feasible on all three specimen. The positional outcome provided more thorough and accurate insight in resulting implant position than could be gathered from distance measurements alone. Observer-related errors were abolished from the process, since the method is largely automatic.ConclusionA novel method of quantifying surgical outcome in orbital reconstructive surgery was presented. The presented Orbital Implant Positioning Frame assessed all parameters involved in implant displacement. The method proved to be viable on three human specimen heads. Clinically, the method could provide direct feedback intraoperatively and could improve postoperative evaluation of orbital reconstructive surgery.

Project description:BACKGROUND:Cardiac hypertrophy induced by pressure overload is one of the important causes of heart failure and sudden cardiac death. At present, there are few studies on the outcome of left ventricular hypertrophy and left ventricular function after complete pressure load removal. OBJECTIVE:This study aims to better simulate the changes of left ventricular structure and function during the process of left ventricular pressure overload and deloading, and to explore the application of echocardiography in it. METHODS:In this study, healthy male (BALB/C) mice were used as research objects to establish an ascending aorta constriction model, to carry out echocardiographic and hemodynamic examinations, to establish an ascending aorta deconstriction model in mice, and to carry out echocardiographic and hemodynamic examinations. RESULTS:Compared with the sham operation group, the left ventricular end-systolic diameter (LVESD), left ventricular end-diastolic diameter (LVEDD), interventricular septal (IVS), and left ventricular posterior wall (LVPW) in the constriction operation group were significantly increased (P=.02, P=.02, P=.02, and P=.02, respectively). LVESD, LVEDD, IVS, and LVPW in the early and late constriction groups were significantly decreased, and the degree of decrease in the early group was greater than that in the late group; compared with the sham operation group, left ventricular diastolic pressure in the constriction operation group increased significantly at 9 and 15 weeks after operation (P=.03). Left ventricular systolic pressure at 15 weeks after operation decreased to a certain extent but was higher than that of the sham operation group (P=.02). The maximal rate of the increase of left ventricular pressure at 3 weeks, 9 weeks, and 15 weeks after operation decreased significantly (P=.03, P=.02, and P=.02, respectively). CONCLUSIONS:In this study, the ascending aorta coarctation model and descending aorta coarctation model were successfully established, which verifies the value of echocardiography information data monitoring in the treatment of left ventricular circulation disorders and the evaluation of surgical treatment.

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Alternative Approaches to the Assessment of the Systemic Circulation and Left Ventricular Performance: A Proof-of-Concept Study.

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Alternative Approaches to the Assessment of the Systemic Circulation and Left Ventricular Performance: A Proof-of-Concept Study.

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