Catheter ablation is a well-established treatment for atrial fibrillation. A subset of patients developed dyspnea secondary to loss of left atrial (LA) compliance after ablation, which is referred as the stiff LA syndrome.¹ Stiff LA syndrome has traditionally been associated with profound eccentric LA remodeling. We report the case of a patient with this clinical syndrome who developed giant V waves during exercise but had a strikingly small LA.

A 76-year-old man who had been a competitive cyclist was referred for invasive hemodynamic exercise testing for evaluation of dyspnea, which had become progressively more severe during the past 3 years. Medical history was notable for chronic systemic hypertension and atrial fibrillation, which had been treated with 3 ablation procedures in the preceding 2 decades. ECG revealed normal sinus rhythm, and transthoracic echocardiography demonstrated normal left ventricular ejection fraction (57%), LA volume of 34 mL (indexed LA volume, 16 mL/m²; Figure), impaired LA reservoir function (LA ejection fraction, 27%), a structurally normal mitral valve with mild regurgitation, normal right ventricular systolic function, and an estimated right ventricular systolic pressure of 36 mm Hg. There was no evidence of pulmonary vein stenosis or pulmonary embolism on computed tomography.

Figure. Pulmonary capillary wedge pressure tracings and echocardiograms at rest and during peak exercise.A, Baseline 4-chamber echocardiogram showing a small left atrium. B, Pulmonary capillary wedge pressure waveforms at rest and (C) during peak exercise. D, Simultaneously obtained sonogram of the lung parenchyma shows development of B lines indicative of interstitial pulmonary congestion. E, Simultaneous echocardiography revealed only mild mitral regurgitation. LV indicates left ventricle. *Peak of the V wave.

Cardiac catheterization revealed mildly elevated right atrial pressure (8 mm Hg) and normal mean pulmonary artery pressure (19 mm Hg) at rest. Pulmonary artery wedge pressure was normal (14 mm Hg at mid C wave) with a prominent V wave (34 mm Hg; Figure). The patient exercised to exhaustion on a supine cycle ergometer achieving a peak workload of 120 W (peak Vo₂, 15.7 mL/min per kg). Right atrial pressure (17 mm Hg) and mean pulmonary arterial pressure (43 mm Hg) increased during exercise. Pulmonary capillary wedge pressure increased to 38 mm Hg, with an increase in the V-wave amplitude to 72 mm Hg (Figure). The patient complained of severe dyspnea, and simultaneous echocardiographic imaging revealed development of sonographic lung B lines (12 lines over 4 left chest sites; Figure) but only mild mitral regurgitation with minimal change in LA volume from rest to peak exercise (31–32 mL). Based on the findings, the diagnosis of the stiff LA syndrome was made.

The stiff LA syndrome is an important complication that may develop years after surgical or catheter ablation.¹ Ablation can prevent LA enlargement because of scarring, but in this case, the LA was exceedingly small, particularly in view of a long-standing history of atrial fibrillation. This suggests that the prior ablation procedures might have caused LA contracture. The normal LA dilates during exercise to augment reservoir function and receive greater venous return from pulmonary veins, protecting the lung capillaries from barotrauma. When the LA volume shrinks, as in this case, this ability to function as a compliance chamber that stores blood during ventricular systole is exhausted, leading to pulmonary venous hypertension with profound increase in the height of the V wave, even in the absence of mitral regurgitation.

LA dilation clearly promotes LA dysfunction, increased filling pressures, and worsening pulmonary hypertension and is an important treatment target.² However, this case illustrates that some degree of LA dilation may also serve as an important compensatory mechanism to protect the lung capillaries from the hydrostatic trauma induced by LA hypertension. With LA contracture, atrial and thus pulmonary venous pressure increases dramatically as the atrium fills to the steeper portion of its compliance curve, leading to the development of so-called giant V waves even in the absence of mitral regurgitation (Figure). The subsequent increase in pulmonary capillary pressure then favors fluid filtration out of the vascular space and into the lung parenchyma, leading to the development of interstitial edema (B lines; Figure [D]) and the perception of dyspnea.³

Treatment remains unknown. Creation of an interatrial septostomy may be helpful to mitigate the pressure rise, as has been performed in patients with heart failure, as well as stiff LA syndrome.^4,5 However, it is unknown whether the septal defect created through these approaches (8 mm) would be sufficient to allow normalization of LA pressure in a case such as this. Prevention may be the most effective treatment. Atrial ablations may reduce LA volume because of myocyte injury, fibrosis, and scar formation. Further study is required to devise less traumatic ablative procedures and to determine whether antifibrotic drugs, such as mineralocorticoid antagonists, may prevent or even reverse LA fibrosis.⁶

In summary, although LA reverse remodeling is a generally a favorable indicator that is associated with lower risk for atrial fibrillation recurrence and better outcomes, the current data suggest that LA volume contraction or failure to dilate could also contribute to pulmonary venous hypertension and symptomatic heart failure in some patients. Further study is needed to better understand the complex role of the LA in patients with cardiovascular disease.

Dr Borlaug has received research funding from the National Heart, Lung, and Blood Institute (RO1 HL128526, R01 HL126638, U01 HL125205, and U10 HL110262). Dr Obokata is supported by a research fellowship from the Uehara Memorial Foundation, Japan.

None.

https://www.ahajournals.org/journal/circheartfailure

导管消融是一种行之有效的心房颤动治疗方法。一部分患者因消融后左心房 (LA) 顺应性丧失而出现继发性呼吸困难，这被称为僵硬 LA 综合征。 ¹左心房僵硬综合征传统上与严重的偏心左心房重塑有关。我们报告了一名患有这种临床综合征的患者的病例，该患者在运动时出现巨大的 V 波，但 LA 却非常小。

一名 76 岁的男子曾是一名自行车竞技运动员，被转诊进行侵入性血流动力学运动测试，以评估呼吸困难的情况，该症状在过去 3 年中逐渐变得更加严重。值得注意的是慢性全身性高血压和心房颤动的病史，在过去 20 年中曾接受过 3 次消融手术治疗。心电图显示窦性心律正常，经胸超声心动图显示左心室射血分数正常（57%），LA 体积为 34 mL（索引 LA 体积，16 mL/m ² ；图），LA 储库功能受损（LA 射血分数，27%） ），结构正常的二尖瓣，轻度反流，右心室收缩功能正常，估计右心室收缩压为 36 mm Hg。计算机断层扫描没有发现肺静脉狭窄或肺栓塞的证据。

数字。休息时和运动高峰时的肺毛细血管楔压描记和超声心动图。 A ，基线四腔超声心动图显示左心房较小。 B ，休息时的肺毛细血管楔压波形和 ( C ) 运动高峰时的肺毛细血管楔压波形。 D ，同时获得的肺实质超声图显示指示间质性肺充血的 B 线的发展。 E ，同步超声心动图仅显示轻度二尖瓣反流。 LV表示左心室。 *V 波的峰值。

心导管检查显示静息时右心房压力轻度升高（8 毫米汞柱），平均肺动脉压力正常（19 毫米汞柱）。肺动脉楔压正常（C 波中部为 14 mm Hg），具有明显的 V 波（34 mm Hg；图）。患者在仰卧自行车测力计上锻炼至力竭，达到 120 W 的峰值工作负荷（峰值 V o ₂ ，15.7 mL/min/kg）。运动期间右心房压力（17 毫米汞柱）和平均肺动脉压力（43 毫米汞柱）增加。肺毛细血管楔压增加至 38 mm Hg，V 波振幅增加至 72 mm Hg（图）。患者主诉严重呼吸困难，同步超声心动图显示超声肺 B 线出现（左胸部 4 个部位 12 条线；图），但仅有轻度二尖瓣反流，LA 体积从休息到峰值运动的变化极小（31-32 mL） ）。根据检查结果，诊断为僵硬性 LA 综合征。

僵硬的 LA 综合征是一种重要的并发症，可能在手术或导管消融术后数年出现。 ¹消融可以防止因疤痕而导致左心房扩大，但在本例中，左心房非常小，特别是考虑到长期存在房颤病史。这表明先前的消融手术可能导致了 LA 挛缩。正常的 LA 在运动过程中会扩张，以增强储库功能并从肺静脉接收更多的静脉回流，从而保护肺毛细血管免受气压伤。当 LA 体积缩小时（如本例所示），这种在心室收缩期间储存血液的顺应室功能就会耗尽，导致肺静脉高压，导致 V 波高度大幅增加，即使在没有二尖​​瓣的情况下也是如此。反流。

LA 扩张明显促进 LA 功能障碍、充盈压升高和肺动脉高压恶化，是重要的治疗目标。 ²然而，该病例说明一定程度的左心室扩张也可能作为一种重要的代偿机制，保护肺毛细血管免受左心室高血压引起的静水损伤。对于 LA 挛缩，当心房填充到其顺应性曲线的较陡部分时，心房和肺静脉压力急剧增加，即使在没有二尖​​瓣反流的情况下也会导致所谓的巨大 V 波的发展（图）。随后肺毛细血管压力的增加有利于液体从血管间隙滤出并进入肺实质，导致间质水肿（B 线；图 [D]）的发展和呼吸困难的感觉。 ³

治疗方法仍未知。房间隔造口术可能有助于减轻压力升高，正如在心力衰竭和僵硬性 LA 综合征患者中所做的那样。 ^4,5然而，在这种情况下，尚不清楚通过这些方法产生的间隔缺损 (8 mm) 是否足以使 LA 压力正常化。预防可能是最有效的治疗方法。由于肌细胞损伤、纤维化和疤痕形成，心房消融可能会减少 LA 体积。需要进一步的研究来设计创伤较小的消融手术，并确定抗纤维化药物（例如盐皮质激素拮抗剂）是否可以预防甚至逆转 LA 纤维化。 ⁶

总之，虽然 LA 逆重构通常是一个有利的指标，与较低的房颤复发风险和更好的结局相关，但目前的数据表明，LA 容量收缩或扩张失败也可能导致肺静脉高压和症状性心力衰竭在一些患者中。需要进一步的研究来更好地了解 LA 在心血管疾病患者中的复杂作用。

Borlaug 博士获得了国家心肺血液研究所的研究资助（RO1 HL128526、R01 HL126638、U01 HL125205 和 U10 HL110262）。小保方博士得到了日本上原纪念基金会的研究奖学金的支持。

 没有任何。

https://www.ahajournals.org/journal/circheartfailure