Yun K L, Fann J I, Rayhill S C, Nasserbakht F, Derby G C, Handen C E, Bolger A F, Miller D C
Department of Cardiovascular Surgery, Stanford University School of Medicine, Calif.
Circulation. 1990 Nov;82(5 Suppl):IV89-104.
The relative importance of the anterolateral (ANTLAT) and posteromedial (POSTMED) papillary muscle (PM) chordae tendineae for left ventricular (LV) segmental wall function was assessed in 12 in situ ejecting canine hearts. Pairs of piezoelectric crystals were placed in the regions subtending PM insertions and the ANTLAT LV free wall to measure wall thickness. After mitral valve replacement with complete preservation of the subvalvular apparatus, chordal attachments to either the ANTLAT PM or POSTMED PM were randomly severed using exteriorized snares, followed by subsequent division of the remaining chordae tendineae. Segmental wall function in each region was determined at each stage by segmental preload recruitable stroke work (sPRSW, slope of the segmental stroke work-end-diastolic wall thickness relation). The order in which the chordae were severed was unimportant (p greater than 0.530 in all regions). When the ANTLAT PM chordae were severed first, there were significant declines in sPRSW without a change in the wall thickness intercept in both the ANTLAT (-71.0 +/- 18.3 vs. -57.7 +/- 16.8 mmHg, p less than 0.05) and POSTMED (-81.8 +/- 23.1 vs. -65.4 +/- 17.3 mmHg, p less than 0.05) PM insertion sites. No further significant reductions in sPRSW in either region were detected after severing the remaining chordal attachments to the POSTMED PM. sPRSW in the ANTLAT LV free wall decreased progressively, reaching statistical significance when both sets of chordae tendineae were divided (-88.3 +/- 14.3 vs. -74.0 +/- 15.2 mm Hg, p less than 0.05). When the POSTMED PM chordae were severed first, no significant changes in sPRSW or the wall thickness intercept in either region of PM insertion were detected. Subsequent division of the ANTLAT PM chordal attachments reduced sPRSW significantly in both the ANTLAT PM (-65.9 +/- 21.1 vs. -56.1 +/- 22.1 mm Hg, p less than 0.05) and POSTMED PM (-78.8 +/- 24.7 vs. -67.2 +/- 24.0 mm Hg, p less than 0.05) insertion sites, without a shift in the wall thickness intercept. In the ANTLAT LV free wall, sPRSW again fell progressively, achieving statistical significance only when both chordal attachments were severed (-78.6 +/- 14.8 vs. -62.2 +/- 13.7 mm Hg, p less than 0.05). In conclusion, division of the chordae tendineae resulted in a decline in segmental LV function not only in the areas subtending PM insertions but also in remote LV regions. Furthermore, the influence of the ANTLAT PM chordae predominated local LV systolic function at both PM insertion sites.(ABSTRACT TRUNCATED AT 400 WORDS)
在12只原位射血的犬心脏中评估了前外侧（ANTLAT）和后内侧（POSTMED）乳头肌（PM）腱索对左心室（LV）节段性室壁功能的相对重要性。将成对的压电晶体置于对应PM附着点和ANTLAT左心室游离壁的区域以测量室壁厚度。在完全保留瓣下结构进行二尖瓣置换术后，使用外置圈套器随机切断与ANTLAT PM或POSTMED PM的腱索附着，随后切断其余腱索。通过节段性预负荷可招募搏功（sPRSW，节段性搏功 - 舒张末期室壁厚度关系的斜率）在每个阶段确定每个区域的节段性室壁功能。腱索切断的顺序并不重要（所有区域p均大于0.530）。当首先切断ANTLAT PM腱索时，ANTLAT（-71.0±18.3 vs. -57.7±16.8 mmHg，p＜0.05）和POSTMED（-81.8±23.1 vs. -65.4±17.3 mmHg，p＜0.05）PM附着点处的sPRSW均显著下降，而室壁厚度截距无变化。切断与POSTMED PM的其余腱索附着后，两个区域的sPRSW均未进一步显著降低。ANTLAT左心室游离壁的sPRSW逐渐下降，当两组腱索均被切断时达到统计学意义（-88.3±14.3 vs. -74.0±15.2 mmHg，p＜0.05）。当首先切断POSTMED PM腱索时，PM附着的两个区域的sPRSW或室壁厚度截距均未检测到显著变化。随后切断ANTLAT PM腱索附着，ANTLAT PM（-65.9±21.1 vs. -56.1±22.1 mmHg，p＜0.05）和POSTMED PM（-78.8±24.7 vs. -67.2±24.0 mmHg，p＜0.05）附着点处的sPRSW均显著降低，室壁厚度截距无偏移。在ANTLAT左心室游离壁，sPRSW再次逐渐下降，仅在两组腱索附着均被切断时达到统计学意义（-78.6±14.8 vs. -62.2±13.7 mmHg，p＜0.05）。总之，腱索切断不仅导致对应PM附着区域的左心室节段性功能下降，还导致左心室远端区域功能下降。此外，ANTLAT PM腱索对两个PM附着点处的局部左心室收缩功能影响更大。（摘要截断于400字）
