Kass D A, Baughman K L, Pak P H, Cho P W, Levin H R, Gardner T J, Halperin H R, Tsitlik J E, Acker M A
Division of Cardiology, Johns Hopkins Medical Institutions, Baltimore, Md 21287, USA.
Circulation. 1995 May 1;91(9):2314-8. doi: 10.1161/01.cir.91.9.2314.
Cardiomyoplasty (CM) is a novel surgical therapy for dilated cardiomyopathy. In this procedure, the latissimus dorsi muscle is wrapped around the heart and chronically paced synchronously with ventricular systole. While studies have found symptomatic improvement from this therapy, the mechanisms by which CM confers benefit remain uncertain. This study sought to better define these mechanisms by means of serial pressure-volume relation analysis.
Serial pressure-volume studies were performed by the conductance catheter method in three patients (total to date) with dilated cardiomyopathy (New York Heart Association class III) who underwent CM. Data were measured at baseline (before surgery) and at 6 and 12 months after CM. Chronic left ventricular (LV) systolic and diastolic changes induced by CM were evaluated with the stimulator in its stable pacing mode (every other beat) and after temporarily suspending pacing. CM-stimulated beats were compared with pacing-off beats to evaluate active systolic assist effects of CM. In each patient, CM resulted in a chronic lowering of cardiac end-diastolic volume and an increased ejection fraction. Most notably, the end-systolic pressure-volume relation shifted leftward, consistent with reversal of chronic chamber remodeling. In contrast, the diastolic pressure-volume relation was minimally altered, and the loops shifted down along the same baseline relation. These marked chronic changes in LV function measurable with CM stimulation off contrasted to only minor acute effects observed when the muscle wrap was activated. This suggests that the benefit of CM derived less from active systolic assist than from remodeling, perhaps because of an external elastic constraint.
These data, while limited to a small number of patients, suggest that CM can reverse remodeling of the dilated failing heart. While systolic squeezing assist effects of CM may play a role in some patients, our study found that this was not required to achieve substantial benefits from the procedure. We speculate that CM may act more passively, like an elastic girdle around the heart, to help reverse chamber remodeling.
心肌成形术（CM）是一种用于治疗扩张型心肌病的新型外科疗法。在此手术中，背阔肌被包裹在心脏周围，并与心室收缩同步进行长期起搏。虽然研究发现这种疗法可改善症状，但CM带来益处的机制仍不明确。本研究试图通过连续压力-容积关系分析来更好地界定这些机制。
采用电导导管法对3例（目前共有）接受CM治疗的扩张型心肌病（纽约心脏协会III级）患者进行连续压力-容积研究。在基线（手术前）以及CM术后6个月和12个月测量数据。在刺激器处于稳定起搏模式（每隔一次心跳）时以及暂时停止起搏后，评估CM引起的慢性左心室（LV）收缩和舒张变化。将CM刺激的心跳与起搏停止后的心跳进行比较，以评估CM的主动收缩辅助效果。在每位患者中，CM导致心脏舒张末期容积慢性降低，射血分数增加。最显著的是，收缩末期压力-容积关系向左移位，这与慢性心室重构的逆转一致。相比之下，舒张期压力-容积关系变化极小，压力-容积环沿相同的基线关系向下移位。关闭CM刺激时可测量到LV功能的这些显著慢性变化，这与激活肌肉包裹时仅观察到的轻微急性效应形成对比。这表明CM的益处更多地源于重构而非主动收缩辅助，可能是由于外部弹性约束。
这些数据虽然仅限于少数患者，但表明CM可以逆转扩张型衰竭心脏的重构。虽然CM的收缩挤压辅助作用可能在一些患者中起作用，但我们的研究发现，要从该手术中获得实质性益处并不需要这一作用。我们推测CM可能更像心脏周围的弹性束带一样被动起作用，以帮助逆转心室重构。
