Pak P H, Maughan L, Baughman K L, Kass D A
Department of Internal Medicine, Division of Cardiology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287, USA.
Circulation. 1996 Jul 1;94(1):52-60. doi: 10.1161/01.cir.94.1.52.
Dynamic diastolic pressure-volume curves measured during filling (PVR fill) in patients with idiopathic hypertrophic cardiomyopathy (HCM) are often considerably shallower than would be anticipated if one assumed high chamber stiffness. We hypothesized that these curves deviate markedly from the passive end-diastolic pressure-volume relation (EDPVR) and explored the mechanisms for such a discordance.
We used invasive pressure-volume analysis and conductance catheter methodology to study 42 patients. Nine had HCM, and the remaining patients comprised three comparison groups: 11 with normal left ventricular (LV) function, 13 with LV hypertrophy secondary to chronic hypertension (LVH-HTN), and 9 with idiopathic dilated cardiomyopathy (DCM). EDPVRs were recorded during balloon catheter obstruction of inferior vena cava inflow. In normal subjects, LVH-HTN patients, and DCM patients, PVR fill curves deviated only slightly from the passive EDPVR. In striking contrast, HCM patients displayed a flat PVR fill that was very different from the steep EDPVR. On reduction of preload, PVR fill relations in HCM shifted downward in parallel, with a net pressure decline at the same chamber volume of -10+/-4 mm Hg. This staircaselike shift was much less in the other patient groups (-2+/-2 mm Hg; P<.001). The unusual behavior in HCM could not be attributed directly to increased viscosity, enhanced pericardial constraint, or preload dependence of isovolumic relaxation. Regional heterogeneity of relaxation may play a role; however, we speculate that the major mechanism relates to the unique fiber and chamber architecture seen with HCM and possibly to enhanced ventricular interaction.
Elevated LV filling pressures in HCM are not due simply to a stiff cavity but also reflect a major influence of offset pressures that vary with chamber loading. The large disparity between flat pressure-volume relations during filling and steep end-diastolic relations appears unique to HCM. This indicates that caution should be used in the interpretation of stiffness results derived from steady-state data and suggests that therapies that alter cavity geometry and/or reduce interaction may markedly influence LV diastolic pressures in HCM.
特发性肥厚型心肌病（HCM）患者在充盈期测量的动态舒张压-容积曲线（PVR fill）通常比假设心室僵硬度高时预期的要浅得多。我们推测这些曲线与被动舒张末期压力-容积关系（EDPVR）有明显偏差，并探讨了这种不一致的机制。
我们采用有创压力-容积分析和电导导管方法研究了42例患者。9例患有HCM，其余患者包括三个对照组：11例左心室（LV）功能正常，13例继发于慢性高血压的LV肥厚（LVH-HTN），9例特发性扩张型心肌病（DCM）。在下腔静脉流入道球囊导管阻塞期间记录EDPVR。在正常受试者、LVH-HTN患者和DCM患者中，PVR fill曲线与被动EDPVR仅略有偏差。与之形成鲜明对比的是，HCM患者的PVR fill曲线平坦，与陡峭的EDPVR非常不同。在降低前负荷时，HCM患者的PVR fill关系平行向下移动，在相同心室容积时净压力下降-10±4 mmHg。这种阶梯状移动在其他患者组中要小得多（-2±2 mmHg；P<0.001）。HCM患者的这种异常行为不能直接归因于粘度增加、心包约束增强或等容舒张期的前负荷依赖性。舒张的区域异质性可能起作用；然而，我们推测主要机制与HCM中独特的纤维和心室结构有关，可能还与增强的心室相互作用有关。
HCM患者左心室充盈压升高不仅是由于心室僵硬，还反映了随心室负荷变化的抵消压力的主要影响。充盈期平坦的压力-容积关系与舒张末期陡峭关系之间的巨大差异似乎是HCM所特有的。这表明在解释从稳态数据得出的僵硬度结果时应谨慎，并表明改变心室几何形状和/或减少相互作用的治疗可能会显著影响HCM患者的左心室舒张压。
