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Mechanism study of pulsus paradoxus using mechanical models.

Xing CY, Cao TS, Yuan LJ, Wang Z, Wang K, Ren HR, Yang Y, Duan YY - PLoS ONE (2013)

Bottom Line: Model 1 demonstrated that the simulated RIPC had different influence on the simulated SVR and PVR.It increased the volume of the simulated right ventricle (SRV) when the internal pressure was kept constant (8.16 cmH2O), while it had the opposite effect on PVR.Our models demonstrate that the different anatomical arrangement of the two venous return systems leads to a different effect of RIPC on right and left ventricles, and thus a pressure gradient across IVS that tends to shift IVS left- and rightwards.

View Article: PubMed Central - PubMed

Affiliation: Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.

ABSTRACT
Pulsus paradoxus is an exaggeration of the normal inspiratory decrease in systolic blood pressure. Despite a century of attempts to explain this sign consensus is still lacking. To solve the controversy and reveal the exact mechanism, we reexamined the characteristic anatomic arrangement of the circulation system in the chest and designed these mechanical models based on related hydromechanic principles. Model 1 was designed to observe the primary influence of respiratory intrathoracic pressure change (RIPC) on systemic and pulmonary venous return systems (SVR and PVR) respectively. Model 2, as an equivalent mechanical model of septal swing, was to study the secondary influence of RIPC on the motion of the interventriclar septum (IVS), which might be the direct cause for pulsus paradoxus. Model 1 demonstrated that the simulated RIPC had different influence on the simulated SVR and PVR. It increased the volume of the simulated right ventricle (SRV) when the internal pressure was kept constant (8.16 cmH2O), while it had the opposite effect on PVR. Model 2 revealed the three major factors determining the respiratory displacement of IVS in normal and different pathophysiological conditions: the magnitude of RIPC, the pressure difference between the two ventricles and the intrapericardial pressure. Our models demonstrate that the different anatomical arrangement of the two venous return systems leads to a different effect of RIPC on right and left ventricles, and thus a pressure gradient across IVS that tends to shift IVS left- and rightwards. When the leftward displacement of IVS reaches a considerable amplitude in some pathologic condition such as cardiac tamponade, the pulsus paradoxus occurs.

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Related in: MedlinePlus

Scheme of Model 2.The right part of the figure is the longitudinal view of Model 2. The materials used are the same as those of Model 1. The top crescent structure is simulated right ventricle (SRV) and the bottom circular one is simulated left ventricle (SLV). Their common wall between SRV and SLV is the simulated interventricular septum. The thickness of the walls are 1.7mm, 3.4mm, 3.4mm from top to bottom in the figure. The left part is the short-axis view of model 2 which looks like a 2D-echocardiogram of the Model. The wall of these bottles are thin plastic and thus can be imaged by echocardiography.
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pone-0057512-g003: Scheme of Model 2.The right part of the figure is the longitudinal view of Model 2. The materials used are the same as those of Model 1. The top crescent structure is simulated right ventricle (SRV) and the bottom circular one is simulated left ventricle (SLV). Their common wall between SRV and SLV is the simulated interventricular septum. The thickness of the walls are 1.7mm, 3.4mm, 3.4mm from top to bottom in the figure. The left part is the short-axis view of model 2 which looks like a 2D-echocardiogram of the Model. The wall of these bottles are thin plastic and thus can be imaged by echocardiography.

Mentions: This model was reformed from the combination of the two parts of Model 1. As figure 3 showed, the simulated right and left ventricles shared the common IVS and the pericardium. All the simulated cavities were filled with water and the pressures in them could be quantitatively adjusted through the connected tubing.


Mechanism study of pulsus paradoxus using mechanical models.

Xing CY, Cao TS, Yuan LJ, Wang Z, Wang K, Ren HR, Yang Y, Duan YY - PLoS ONE (2013)

Scheme of Model 2.The right part of the figure is the longitudinal view of Model 2. The materials used are the same as those of Model 1. The top crescent structure is simulated right ventricle (SRV) and the bottom circular one is simulated left ventricle (SLV). Their common wall between SRV and SLV is the simulated interventricular septum. The thickness of the walls are 1.7mm, 3.4mm, 3.4mm from top to bottom in the figure. The left part is the short-axis view of model 2 which looks like a 2D-echocardiogram of the Model. The wall of these bottles are thin plastic and thus can be imaged by echocardiography.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585346&req=5

pone-0057512-g003: Scheme of Model 2.The right part of the figure is the longitudinal view of Model 2. The materials used are the same as those of Model 1. The top crescent structure is simulated right ventricle (SRV) and the bottom circular one is simulated left ventricle (SLV). Their common wall between SRV and SLV is the simulated interventricular septum. The thickness of the walls are 1.7mm, 3.4mm, 3.4mm from top to bottom in the figure. The left part is the short-axis view of model 2 which looks like a 2D-echocardiogram of the Model. The wall of these bottles are thin plastic and thus can be imaged by echocardiography.
Mentions: This model was reformed from the combination of the two parts of Model 1. As figure 3 showed, the simulated right and left ventricles shared the common IVS and the pericardium. All the simulated cavities were filled with water and the pressures in them could be quantitatively adjusted through the connected tubing.

Bottom Line: Model 1 demonstrated that the simulated RIPC had different influence on the simulated SVR and PVR.It increased the volume of the simulated right ventricle (SRV) when the internal pressure was kept constant (8.16 cmH2O), while it had the opposite effect on PVR.Our models demonstrate that the different anatomical arrangement of the two venous return systems leads to a different effect of RIPC on right and left ventricles, and thus a pressure gradient across IVS that tends to shift IVS left- and rightwards.

View Article: PubMed Central - PubMed

Affiliation: Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, China.

ABSTRACT
Pulsus paradoxus is an exaggeration of the normal inspiratory decrease in systolic blood pressure. Despite a century of attempts to explain this sign consensus is still lacking. To solve the controversy and reveal the exact mechanism, we reexamined the characteristic anatomic arrangement of the circulation system in the chest and designed these mechanical models based on related hydromechanic principles. Model 1 was designed to observe the primary influence of respiratory intrathoracic pressure change (RIPC) on systemic and pulmonary venous return systems (SVR and PVR) respectively. Model 2, as an equivalent mechanical model of septal swing, was to study the secondary influence of RIPC on the motion of the interventriclar septum (IVS), which might be the direct cause for pulsus paradoxus. Model 1 demonstrated that the simulated RIPC had different influence on the simulated SVR and PVR. It increased the volume of the simulated right ventricle (SRV) when the internal pressure was kept constant (8.16 cmH2O), while it had the opposite effect on PVR. Model 2 revealed the three major factors determining the respiratory displacement of IVS in normal and different pathophysiological conditions: the magnitude of RIPC, the pressure difference between the two ventricles and the intrapericardial pressure. Our models demonstrate that the different anatomical arrangement of the two venous return systems leads to a different effect of RIPC on right and left ventricles, and thus a pressure gradient across IVS that tends to shift IVS left- and rightwards. When the leftward displacement of IVS reaches a considerable amplitude in some pathologic condition such as cardiac tamponade, the pulsus paradoxus occurs.

Show MeSH
Related in: MedlinePlus