Ebook Practical cardiovascular hemodynamics: Part 2
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Ebook Practical cardiovascular hemodynamics: Part 2
X11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2 until the pressure inside these chambers equalizes with the intrapericardial pressure (Figure X11I.1).1-5 This leads to equalization of diastolic pressures of the 4 cardiac chambers. Because the rightsided chambers have thin walls, they tend to collapse when intrapericardial pressure is equal to or Ebook Practical cardiovascular hemodynamics: Part 2 larger than their intracavitary pressure.FIGURE XIII.1Pressure-volume curve of the pericardium showing th intrapericardial pressure in rapidly and slEbook Practical cardiovascular hemodynamics: Part 2
owly developing effusions or cardiac dilatation. In acute conditions, the pericardium cannot stretch, and its pressure rises markedly with small volumX11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2eading to a “functional” CP. Once the pericardial pressure exceeds a stretch limit (bar), it increases exponentially with any change in volume. Even when intrapericardial pressure is lower than right-sided pressure, the RV or RA transmural pressure (RA pressure or RV pressure minus intrapericardial Ebook Practical cardiovascular hemodynamics: Part 2pressure) is reduced, which impairs RV outward expansion and filling; in addition, at this point, pericardial pressure is at a steep slope, and thereEbook Practical cardiovascular hemodynamics: Part 2
is at least a threatened tamponade. Although fluid administration may initially increase RV pressure and RV transmural pressure, intracardiac volume cX11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2stration in euvolemic or hypervolemic patients may be harmful.This graph also shows that patients with high intrapericardial pressure resulting from CP or severe RV dilatation stretching the pericardium may have LVEDP >20 mmHg, yet the transmural LV pressure is almost nil and the LV volume cannot ex Ebook Practical cardiovascular hemodynamics: Part 2pand. These patients have low LV volume yet increased pulmonary capillary pressure. The amount of fluid in the pulmonary veins is modest, and thus, thEbook Practical cardiovascular hemodynamics: Part 2
e lungs are almost always clear despite sometimes severe dyspnea. Modified from spodick I)H. Acme cardiac tamponade. N Engl J Med. 2003; 349: 684-690.X11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2ure are transmitted to the cardiac chambers.1'2 This explains why RA pressure decreases during inspiration and thus venous flow from the SVC to the RA increases during inspiration (absence of the Kussmaul’s sign). Left-sided flow does not increase because pulmonary veins and LV are both exposed to t Ebook Practical cardiovascular hemodynamics: Part 2he negative intrathoracic pressure; actually, the pulmonary veins are more affected by this negative pressure. The increased venous flow to the rightEbook Practical cardiovascular hemodynamics: Part 2
cavities makes the RV push against the LV in diastole, rather than push against the pericardium since the high pericardial pressure prevents that. ThiX11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2III.2;.FIGURE XIIL2Sequence of events during inspiration in tamponade. (-) sign adjacent to a structure signifies there is transmission of the negative intrathoracic pressure to this structure, whereas (Ơ) corresponds to the lack of transmission of the intrathoracic pressure to this structure. Gray Ebook Practical cardiovascular hemodynamics: Part 2arrows signify increased flow between 2 chambers, whereas the blue arrows signify reduced flow between 2 chambers.During inspiration, the negative preEbook Practical cardiovascular hemodynamics: Part 2
ssure is trans https://khothuvien.coni and SVC and to the intracardiac chambers (this is difki^nv x,vu.constriction). This increases flow between bothX11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2t is deep especially during inspiration, but Y descent is flat because of impeded RA-to-RV flow throughout all diastole, including early diastole.E: mitral inflow Doppler wave; PV: pulmonary vein; S: systolic flow wave of IVC, SVC, and PV on Doppler, corresponds to X descent; D: diastolic flow wave Ebook Practical cardiovascular hemodynamics: Part 2of I VC, SVC, and PV on Doppler, corresponds to Y descent.Although ventricular interdependence is present in both CP and tamponade, a different mechanEbook Practical cardiovascular hemodynamics: Part 2
ism is incriminated in each case: during inspiration, RV pushes LV in tamponade, whereas RV is sucked by LV in CP. As opposed to CP, LV flow is reduceX11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers Ebook Practical cardiovascular hemodynamics: Part 2the uniform pericardial fluid, the constraint is more uniform across both LV and RV in case of tamponade. As a result of this different mechanism, ventricular interdependence is more prominent in tamponade and leads to pulsus paradoxus, which IS only present in one third of cases of CP.Furthermore, Ebook Practical cardiovascular hemodynamics: Part 2as opposed to CP where the heart briefly expands in early diastole before getting constrained, the heart is compressed throughout all diastole in tampEbook Practical cardiovascular hemodynamics: Part 2
onade, including early diastole. Thus, RA-to-RV flow is impeded throughout all diastole, including early diastole, and there is no deep Y on the RA trX11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambers X11L1. OVERVIEW OF THE HEMODYNAMICS OIIn tamponade, intrapericardial pressure usually increases to -10 to 25 mmHg and compresses the cardiac chambersGọi ngay
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