Effects of controlled antegrade pulmonary blood flow on cardiac function after bidirectional cavopulmonary anastomosis

BACKGROUND: Bidirectional cavopulmonary anastomosis (BCPA) has been used as an intermediate stage in the treatment of patients with single-ventricle physiology. Leaving additional antegrade pulmonary blood flow has been shown to improve postoperative arterial blood oxygen saturations; however, controversy continues over whether the potential increase in systemic venous pressure is detrimental. We studied the effects of controlled antegrade pulmonary blood flow on cardiac function in patients after BCPA. METHODS: From January 1993 to July 2000, 128 patients underwent BCPA. Mean age at operation was 6.2 +/- 4 months (range 2 to 36 months). In group 1 (n = 72), restricted antegrade pulmonary blood flow was maintained through a native narrowed pulmonary valve or by adjustment of previously placed pulmonary artery band with the goal of maintaining the mean pulmonary artery pressure less than 16 mm Hg. In group 2 (n = 56), BCPA was the only source of pulmonary blood flow. RESULTS: One hospital death (0.8%) occurred. The mean pulmonary artery pressure at the end of the operation was 13 +/- 2 mm Hg in group 1 compared with 12 +/- 2 mm Hg in group 2, a difference that was not significant. Patients in group 1 had higher arterial oxygen saturations (84% +/- 3% compared with 74% +/- 3% in group 2, p < 0.05), and shorter mean hospital stay (9 +/- 3 days compared with 15 +/- 2 days, p < 0.05). Persistent pleural effusion (> 10 days) or late chylothorax occurred in 4 patients from group 1 and 3 from group 2, a difference that was not significant. During a mean follow-up of 36 +/- 10 months no late deaths occurred. The mean oxygen saturation remained higher in group 1, 80% +/- 3% compared with 74% +/- 4% in group 2, and the hematocrit was lower, at 38% +/- 3% compared with 46% +/- 4% (p < 0.05 for both comparisons). Cardiac catheterizations were performed in 68 patients before completion Fontan. Total pulmonary artery (Nakata) index was 263 +/- 34 mm(2)/m(2) in group 1 (n = 40) and 188 +/- 13 mm(2)/m(2) in group 2 (n = 28) (p < 0.05). The mean pulmonary artery pressure and mean ventricular end-diastolic pressure were similar. CONCLUSIONS: Controlled antegrade pulmonary blood flow may have favorable effects on cardiac function for a selected group of patients and does not appear to have adverse effects on subsequent suitability for completion Fontan.     

The unifocal bilateral bidirectional cavopulmonary anastomosis

We propose a new surgical technique to manage the presence of bilateral superior venae cavae in single ventricle patients, a recognized risk factor for both bidirectional Glenn anastomosis and Fontan completion. The idea is to convert two small, peripheral and competing bilateral bidirectional cavopulmonary anastomoses into a single, larger, and centrally located cavopulmonary connection. This technique, used in 2 patients, provides a symmetrical distribution of pulmonary blood flow and may, in fact, yield growth of the central pulmonary arteries as well as prevent thrombus formation.     

Development of pulmonary arteriovenous fistulas after bidirectional cavopulmonary shunt

Background. A high incidence of pulmonary arteriovenous fistulas (PAVF) has been reported after bidirectional cavopulmonary shunt (BCPS) or total cavopulmonary shunt (TCPS; BCPS in patients with interrupted inferior vena cava). However, the definite diagnostic criteria or standard diagnostic modality of PAVF has not yet been defined. The goal of this study was to evaluate the diagnostic modalities and the prevalence of PAVF.

Methods. We selected 10 patients with TCPS and 27 patients with BCPS. Lung perfusion scan, contrast echocardiogram, and pulmonary angiogram were performed. The results were compared among groups of patients and among each diagnostic modality.

Results. All 10 patients with TCPS and 16 and 13 patients with BCPS showed positive results on contrast echocardiograms and lung scans, respectively. Six patients with TCPS and 4 patients with BCPS showed positive results on pulmonary angiograms. All patients with TCPS developed subclinical or clinical PAVF and 19 patients with BCPS developed subclinical PAVF and none of them had clinical PAVF during the short-term follow-up.

Conclusions. Most patients with bidirectional cavopulmonary anastomosis have subclinical evidence of right-to-left intrapulmonary shunting. This problem can be demonstrated with various diagnostic modalities.     

Rapid onset of pulmonary arteriovenous malformations after cavopulmonary anastomosis.

The reported incidence of pulmonary arteriovenous malformations after superior cavopulmonary anastamosis in patients with heterotaxia syndrome is 18%-21%. The manifestation is usually in young children and the onset is gradual. We report an unusual case of pulmonary arteriovenous malformations developing within 72 hours of bilateral superior cavopulmonary anastamosis (Kawashima procedure) in an adolescent with heterotaxia syndrome.     

Oral sildenafil ameliorates impaired pulmonary circulation early after bidirectional cavopulmonary shunt

We report a case of successful administration of oral sildenafil (ie, a phosphodiesterase-5 inhibitor) in an infant for impaired pulmonary circulation that caused early clinical deterioration after a bicavopulmonary shunt. The transpulmonary pressure gradient (ie, a clinical indicator of pulmonary circulation) was initially normalized by inhaled nitric oxide; however, an increase in transpulmonary pressure gradient and oxygen desaturation occurred after extubation and discontinuation of inhaled nitric oxide on postoperative day 1. Subsequent administration of oral sildenafil in stepwise doses resulted in normalization of transpulmonary pressure gradient and improved oxygen saturation with successful discontinuation of intravenous vasodilators. Our results suggest that oral sildenafil may be a potent adjunctive therapy for impaired postoperative pulmonary circulation after right heart bypass surgery.     

New approach to the surgical management of pulmonary arteriovenous malformations after cavopulmonary anastomosis

The development of pulmonary arteriovenous malformations after cavopulmonary bypass in patients with congenital heart disease is well documented. We report successful management of pulmonary arteriovenous malformations after cavopulmonary bypass in a patient with an interrupted inferior vena cava (IVC) and multiple hepatic veins utilizing an extracardiac conduit from the hepatic veins to the hemiazygous continuation of the interrupted IVC. This technique, performed without circulatory arrest or an atriotomy, may limit morbidity associated with intracardiac procedures in patients with single ventricle morphology. Furthermore, this case suggests an alternative technique for completion Fontan in patients with an interrupted IVC and multiple hepatic venous drainage.     

双向腔肺分流术后不同通气程度对脑血流的影响

目的 观察双向腔肺分流术后不同通气程度对脑血流及系统氧饱和度的影响.方法 随机抽取8例功能性单心室行双向腔肺分流术病儿.术后3～5 h血流动力学平稳后进行研究,初始呼吸机参数设定容量控制的SIMV模式.通过调整呼吸机频率获得不同通气状态.更换通气状态后20 min记录数据,记录3种连续的通气状态下动脉血气分析、血流动力学指标、颈内动脉多普勒血流频谱,用近红外组织血氧监测仪持续监测脑组织血氧参数.结果 高通气状态下,动脉血压和上腔静脉压明显下降,平均动脉氧分压和二氧化碳分压明显下降.反映脑血流量的指标颈内动脉血流峰值速度以及脑组织中含氧血红蛋白的含量也明显下降.而在低通气状态下,可以观察到相反的结果.结论 不同通气状态可以明显影响双向腔肺分流术后血流动力学状况、动脉氧饱和度及脑血流量.与高通气相比,低通气状态降低脑血管床阻力,因此可以增加双向腔肺分流术后脑一肺串联的血流量,提高双向腔肺分流术后氧饱和度.     

Immediate results of bidirectional cavopulmonary anastomosis and Fontan operations in adults

The purpose of this study is to analyze the immediate results of bidirectional cavopulmonary anastomosis (BCPA) and Fontan operations performed in adults, and to reveal the risk factors. During the years 1983-2010, 681 consecutive patients underwent BCPA or a Fontan operation. Fifty-three of 681 patients were more than 18?years of age. Twenty-nine adults underwent BCPA and 24 underwent a Fontan operation. Immediate results of surgical treatment were followed during the hospital period. The average number of exceeded 'operability' criteria by Choussat et al. [Choussat A, Fontan F, Besse P, Vallot F, Chauve A, Bricaud H. Selection criteria for Fontan procedure. In: Anderson RH, Shinebourne EA, editors. Pediatric Cardiology. Edinburgh: Churchhill Livingstone, 1977:559-566] was significantly higher in patients from the BCPA group compared to the Fontan group (1.3±0.8 vs. 0.9±0.7, P=0.034). Hospital mortality after BCPA in adults was 6.9% (2/29) and did not differ from children (7.1%, 19/268), P=0.634. Hospital mortality after Fontan operation in adults was 8.3% (2/24) and did not differ from children (11.9%, 43/360), P=0.419. The frequency of non-lethal hospital complications was higher in patients after a Fontan operation. Patients from the Fontan group more frequently developed arrhythmias and prolonged pleural effusions. Preoperative regurgitation at atrioventricular valves was an independent risk factor for hospital mortality and morbidity after a Fontan operation. BCPA and Fontan operations performed in adults are accompanied by good immediate results and considerably improves patients' condition.     

Long-term results after cavopulmonary anastomosis

Brief case histories of three patients who underwent cavopulmonary anastomosis 28, 27, and 26 years ago, respectively, are presented. From this limited sample the following conclusions may be drawn. (1) Long-term survival with good functional results in patients with complex congenital anomalies who undergo cavopulmonary shunting at an early age is possible. (2) Secondary changes in the circulation of the right lung such as underperfusion of the upper lobe and the development of multiple arteriovenous connections in the lower lobe do occur, maybe more often than appreciated. (3) By 15 to 20 years after their initial operation, most of these patients require additional operations such as systemic-pulmonary artery shunt or, if possible, total repair of their underlying anomaly.     

年龄与双向腔肺吻合术后发绀改善的早期临床研究

目的　回顾评价双向腔肺吻合术 (BCPA)后早期 ,年龄因素对发绀改善情况的影响。方法　 1992年 6月至 2 0 0 0年 12月行BCPA术 6 8例。 6 3例在体外循环下手术 ,5例在常温非体外循环下手术。结果　动脉血氧饱和度 (SaO2 )大于 0 80者 47例 ,年龄 0 3～ 8岁 ,平均 ( 3 5± 2 0 )岁 ,体表面积0 2 7～ 0 86m2 ,平均 ( 0 5 6± 0 .14)m2 ;SaO2 小于 0 80者 2 1例 ,年龄 1 3～ 16岁 ,平均 ( 7 7± 3 9)岁 ,体表面积 0 41～ 1 44m2 ,平均 ( 0 82± 0 2 3)m2 。SaO2 与病儿年龄、体表面积的相关系数分别为 - 0 6 4、- 0 6 0。在年龄大于 5 95岁和 (或 )体表面积大于 0 72m2 时 ,术后SaO2 小于 0 80。 1例死亡。结论　BCPA应早实施 ,并严密随访。尽早改行全腔肺吻合术。     

呼吸对全腔肺动脉吻合术后肺循环血流的影响

目的探讨呼吸对全腔肺动脉吻合术后肺循环血流的影响。方法对15例全腔肺动脉吻合术后的患儿进行超声检查,观察在静息及深呼吸条件下肺循环血流的变化特征。结果应用外管道的患儿,静息状态下,肺动脉为持续性前向血流,血流速为（38.0±2.3）cm/s;深吸气时前向流速增大为（67.0±3.5）cm/s;深呼气时前向流速减小为（26.0±2.3）cm/s,与静息状态时相比,差异均有极显著性意义（P＜0.01）。应用内隧道的患儿,其肺动脉血流同时要受心动周期的影响,静息状态下,上腔静脉为持续性血流,血流速为（42.0±2.1）cm/s;深吸气时流速增大为（71.0±4.3）cm/s;深呼气时流速减小为（21.0±1.0）cm/s,与静息状态时相比,差异均有极显著性意义（P＜0.01）,且无反向血流。应用人工血管外管道的患儿,吸气时,下腔静脉为峰值（37.0±2.3）cm/s的前向血流,呼气时为峰值（33.0±1.7）cm/s的反向血流;应用带瓣的同种血管外管道的患儿,吸气时下腔静脉为峰值（47.0±1.9）cm/s的前向血流,呼气时无前向流,且无明显反向血流。结论呼吸是全腔肺动脉吻合术后肺循环的另一能量来源;带瓣外管道可以减少或完全防止下腔静脉呼气时的反向血流。     

Pulmonary arteriovenous malformations after cavopulmonary anastomosis

Pulmonary arteriovenous malformations (PAVMs) are a cause of progressive cyanosis after cavopulmonary anastomosis in children with single ventricle physiology who are on the pathway leading to a Fontan procedure. Investigations into possible mechanisms for the etiology of PAVMs are ongoing and suggest that the liver might play a key regulatory role in the development of these lesions.     

Hypoventilation improves oxygenation after bidirectional superior cavopulmonary connection

OBJECTIVE: Bidirectional superior cavopulmonary connection may be complicated by systemic hypoxemia. Previous work has shown that hyperventilation worsens systemic oxygenation in patients after bidirectional superior cavopulmonary connection. The likely mechanism is that hyperventilation-induced hypocarbia decreases cerebral, superior vena caval, and pulmonary blood flow. The aim of the current study was to determine whether the converse approach, hypoventilation, improves oxygenation after bidirectional superior cavopulmonary connection. METHODS: This is a prospective, patient-controlled study of 15 patients (median age 8.0 months, range 4.7-15.5) who underwent bidirectional superior cavopulmonary connection. Patients were studied in the intensive care unit, within 8 hours of surgery, while sedated, paralyzed, and mechanically ventilated. To avoid acidosis during hypoventilation, sodium bicarbonate was administered before hypoventilation. Cerebral blood flow velocity was measured by transcranial Doppler sonography of the middle cerebral artery. RESULTS: Hypoventilation following administration of sodium bicarbonate (pH-buffered hypoventilation) produced hypercarbia (mean Pco(2) = 58 mm Hg versus 42 mm Hg at baseline). During hypoventilation, there were significant increases in both mean arterial Po(2) (from 50 mm Hg at baseline to 61 mm Hg; P <.05) and mean systemic oxygen saturation (from 86% at baseline to 90%; P <.05). These increases occurred despite accompanying, small increases in pulmonary artery pressure and transpulmonary gradient. Hypoventilation also produced an increase in mean cerebral blood flow velocity (from 37 cm/s at baseline to 55 cm/s; P <.05) and a decrease in the arteriovenous oxygen saturation difference across the upper body (from 33% at baseline to 23%; P <.05), consistent with increased cerebral blood flow. CONCLUSIONS: This study demonstrates that hypoventilation improves systemic oxygenation in patients after bidirectional superior cavopulmonary connection. The likely mechanism for this effect is that hypoventilation-induced hypercarbia decreases cerebral vascular resistance, thus increasing cerebral, superior vena caval, and pulmonary blood flow. Hypoventilation may be a useful clinical strategy in patients who are hypoxemic in the early postoperative period after bidirectional superior cavopulmonary connection.