Balloon atrial septostomy in end-stage pulmonary hypertension guided by a novel intracardiac echocardiographic transducer

First in-human modified atrial septostomy combining radiofrequency ablation and balloon dilation

OBJECTIVE

Preclinical research suggests that the combined use of radiofrequency ablation and balloon dilation (CURB) could create stable interatrial communications without device implantation. This study examined the first in-human use of CURB for modified atrial septostomy in patients with severe pulmonary arterial hypertension (PAH).

METHODS

Between July 2018 and October 2021, CURB was performed in 19 patients with severe PAH (age: 31.5±9.1 years; mean pulmonary artery pressure: 73 mm Hg (IQR: 66-92); pulmonary vascular resistance: 18.7 Wood units (IQR: 17.8-23.3)). Under guidance of intracardiac echocardiography and three-dimensional location system, (1) fossae ovalis was reconstructed and ablated point-by-point with radiofrequency; (2) then graded balloon dilation was performed after transseptal puncture and the optimal size was determined according to the level of arterial oxygen saturation (SatO₂); (3) radiofrequency ablation was repeated around the rims of the created fenestration. The interatrial fenestrations were followed-up serially.

RESULTS

After CURB, the immediate fenestration size was 4.4 mm (IQR: 4.1-5.1) with intracardiac echocardiography, systolic aortic pressure increased by 10.2±6.9 mm Hg, cardiac index increased by 0.7±0.3 L/min/m² and room-air resting SatO2 decreased by 6.2±1.9% (p<0.001). One patient experienced increased pericardiac effusion postoperatively; the others had no complications. On follow-up (median: 15.5 months), all interatrial communications were patent with stable size (intraclass correlation coefficient=0.96, 95%CI:0.89 to 0.99). The WHO functional class increased by 1 (IQR: 1-2) (p<0.001) with improvement of exercise capacity (+159.5 m, P<0.001).

CONCLUSION

The interatrial communications created with CURB in patients with severe PAH were stable and the mid-term outcomes were satisfactory.

TRIAL REGISTRATION NUMBER

NCT03554330.

Interventional Therapies in Pulmonary Hypertension

Despite advances in drug therapy, pulmonary hypertension-particularly arterial hypertension (PAH)-remains a fatal disease. Untreatable right heart failure (RHF) from PAH eventually ensues and remains a significant cause of death in these patients. Lowering pulmonary input impedance with different PAH-specific drugs is the obvious therapeutic target in RHF due to chronically increased afterload. However, potential clinical gain can also be expected from attempts to unload the right heart and increase systemic output. Atrial septostomy, Potts anastomosis, and pulmonary artery denervation are interventional procedures serving this purpose. Percutaneous balloon pulmonary angioplasty, another interventional therapy, has re-emerged in the last few years as a clear alternative for the management of patients with distal, inoperable, chronic thromboembolic pulmonary hypertension. The current review discusses the physiological background, experimental evidence, and potential clinical and hemodynamic benefits of all these interventional therapies regarding their use in the setting of RHF due to severe pulmonary hypertension.

Interventional and surgical therapeutic strategies for pulmonary arterial hypertension: Beyond palliative treatments

Despite significant advances in pharmacological treatments, pulmonary arterial hypertension remains an incurable disease with an unreasonably high morbidity and mortality. Although specific pharmacotherapies have shifted the survival curves of patients and improved exercise endurance as well as quality of life, it is also true that these pharmacological interventions are not always accessible (particularly in developing countries) and, perhaps most importantly, not all patients respond similarly to these drugs. Furthermore, many patients will continue to deteriorate and will eventually require an additional, non-pharmacological, intervention. In this review we analyze the role of atrial septostomy and Potts anastomosis in the management of patients with pulmonary arterial hypertension, we summarize the current worldwide clinical experience (case reports and case series), and discuss why these interventional/surgical strategies might have a therapeutic role beyond that of a "bridge" to transplantation.

Atrial Septostomy: A Contemporary Review

Pulmonary arterial hypertension (PAH) is a rare disease, but it boasts significant morbidity and mortality. Although remarkable achievements have been made in the medical treatment of PAH, there is a role for invasive or surgical procedures in patients with progressive disease despite optimal medical therapy or with no access to such therapy. Atrial septostomy creates a right-to-left intracardiac shunt to decompress the overloaded right ventricle. Despite significant advances to validate and improve this palliative procedure, as well as recent reports of improved outcomes, it is only slowly being adopted. This article aims to detail the history, indications, contraindications, procedural techniques, and outcomes of atrial septostomy. We will also shed light on some of the newer interventions, inspired by the same physiological concept, that are being evaluated as potential palliative modalities in patients with PAH.

Saudi Guidelines on the Diagnosis and Treatment of Pulmonary Hypertension: Medical and surgical management for pulmonary arterial hypertension

Prior to the availability of the pulmonary arterial hypertension (PAH)-specific therapy, PAH was a dreadful disease with a very poor prognosis. Better understanding of the complex pathobiology of PAH has led to a major therapeutic evolution. International regulatory agencies have approved many specific drugs with different pharmacologic pathways and routes of administration. In the year 2013, two new drugs with great potentials in managing PAH have been added to the treatment options, macitentan and riociguat. Additional drugs are expected to come in the near future.

A substantial body of evidence has confirmed the effectiveness of pulmonary arterial hypertension (PAH)-specific therapies in improving the patients’ symptomatic status and slowing down the rate of clinical deterioration.

Although the newer modern medications have significantly improved the survival of patients with PAH, it remains a non-curable and fatal disease. Lung transplantation (LT) remains the only therapeutic option for selected patients with advanced disease who continue to deteriorate despite optimal therapy.

Atrial septostomy in patients with pulmonary hypertension: should it be recommended?

Treatment options for patients with advanced pulmonary hypertension (PH) are limited. Iatrogenic creation of an interatrial communication (i.e., atrial septostomy [AS]) has been suggested as a possible treatment option or as a bridge to transplantation in selected patients and has been incorporated into current PH guidelines. Uptake of the procedure has been slow and the worldwide experience with AS is limited to approximately 280 published cases, over a period of more than 25 years. The rationale for creating an AS has been provided by the observation that patients with congenital heart disease, shunt lesions and PH have a better survival compared with patients with idiopathic PH. We review pathophysiologic data and the published clinical experience and discuss the rationale, indication and potential pitfalls of AS in patients with severe PH.

Imaging of the heart in pulmonary hypertension

Pulmonary hypertension (PH) is a disease of the pulmonary arteries resulting in a progressive increase in pulmonary vascular resistance, ultimately leading to right ventricular failure and death. It is a rare disease with a poor prognosis. The functional capacity of the right ventricle (RV) is a major prognostic determinant in PH. Our understanding of RV performance in PH has been hindered by the lack of techniques that give a reliable picture of right ventricular morphology and function. There have been recent major advances in our understanding of the mechanism of disease development, in the diagnostic process and in the treatment of PH. There are now three classes of medications that are effective in the treatment of PH: prostanoids, endothelin receptor antagonists and phosphodiesterase-5 inhibitors. Therapeutic advances in the management of PH have reinforced the requirement for non-invasive, accurate and reproducible methods of assessment to act as 'end-points' to measure the effects of treatment. It is our opinion that the most useful 'end-point' would be one that evaluates right heart morphology and function. We introduce and discuss the techniques currently used to image the heart in patients with PH. Imaging modalities discussed include echocardiography, radionuclide ventriculography, cardiac computed tomography and cardiac magnetic resonance (CMR) imaging focusing on the rapidly evolving technique of CMR imaging.

Surgical therapies for pulmonary arterial hypertension

Surgical therapies for the treatment of pulmonary arterial hypertension typically are reserved for patients who are deemed to be refractory to medical therapy and have evidence of progressive right-sided heart failure. Atrial septostomy, a primarily palliative procedure, may stave off hemodynamic collapse from right-sided heart failure long enough to permit a more definitive surgical treatment such as lung or combined heart-lung transplantation. This article discusses indications for and results of atrial septostomy and lung and heart-lung transplantation in patients who have pulmonary arterial hypertension.

Risk of cardiac catheterization under anaesthesia in children with pulmonary hypertension

BACKGROUND

Children with primary pulmonary hypertension (PHT) are a high-risk group who require assessment by cardiac catheterization under anaesthesia. Complications, including death, have occurred during anaesthesia in these patients, but the true risk has not been quantified.

METHODS

The clinical records of children with PHT undergoing general anaesthesia for pulmonary vascular resistance studies were reviewed retrospectively. Data collected included pre-catheter measures of severity of disease, details of clinical management, and complications occurring within 24 h of the start of anaesthesia.

RESULTS

During the past 5 yr, 75 consecutive patients were catheterized and usable records were available in 70. The age range was 0.1-18 yr (mean 7.1). Four children required external cardiac massage [6% (95% confident limits 1-11%)] and one of these died. Of the four, two had an arrhythmia related to the mechanical effects of catheterization, one was hypotensive during anaesthesia and the other had fatal cardiac failure in recovery. All four had severe PHT as judged by echocardiographic estimation of tricuspid regurgitant jet velocity>4 m s-1.

CONCLUSIONS

Resuscitation or death occurred in 6% of cases. Any associated risk factors could not be determined because the number of complications was too small. Risks may be highest in children with severe idiopathic PHT and symptoms of chest pain, syncope, or dizziness.

Insertion of a Fenestrated Amplatzer Atrial Septostomy Device for Severe Pulmonary Hypertension

Atrial septostomy is a palliative treatment for severe pulmonary hypertension. We report the insertion of a novel custom-made fenestrated Amplatzer atrial septostomy device following repeat atrial septostomy for severe pulmonary hypertension in a terminally ill patient with scleroderma resulting in 6 months of palliation.

Interventional and surgical modalities of treatment for pulmonary arterial hypertension

Beyond medical therapy, different interventional and surgical approaches exist for treatment of pulmonary arterial hypertension (PAH). Atrial septostomy has been applied in patients with lack of response to medical therapy in the absence of other surgical treatment options. With growing experience, procedure-related death rates have been reduced to 5.4%, and the most suitable patient group has been identified among patients with a mean right atrial pressure between 10 and 20 mm Hg. Pulmonary endarterectomy is the accepted form of treatment for patients with chronic thromboembolic pulmonary hypertension. Establishing the diagnosis and the classification of the type of lesions by pulmonary angiography is crucial for optimal patient selection. Perioperative mortality rates have been reduced to <10% in experienced centers, and the hemodynamic improvement is dramatic and sustained. Lung and heart-lung transplantation remains the procedure of choice for patients unsuitable for other treatment modalities. Timing of the procedure is difficult because waiting times vary between centers and usually are in a high range. Early referral of patients unresponsive to other treatment forms is therefore of importance to avoid transplantation of patients with established significant comorbidity. The survival rate during the first five years after transplantation for PAH is intermediate among the lung diseases, lower than chronic obstructive pulmonary disease but higher than idiopathic pulmonary fibrosis.

Contemporary management of children with atrial septal defects: a focus on transcatheter closure

Atrial septal defects that result in right atrial and ventricular volume overload should be closed if diagnosed in children and adolescents. With closure of the atrial septal defect, the left-to-right shunt is eliminated e.g. the volume loading of the right heart, the excessive pulmonary blood flow and the total cardiac work load are reduced. The possibility of future arrhythmic events is lessened and paradoxical emboli across the septum eliminated. The first intracardiac surgical repair of a congenital lesion was a defect in the atrial septum nearly 50 years ago. Surgical closure remains a valuable, although viable technique. Recently percutaneous transcatheter techniques are now available. The conventional approach is via a median sternotomy incision but is associated with pain, risk of wound infection, postoperative immobilization and a permanent scar. It has been suggested that alternative approaches such as surgical repair using mini-sternotomy or lateral thoracotomy incisions yield similar results to the conventional surgical technique and are associated with fewer adverse effects. Transcatheter closure has developed over the last two decades and has evolved into a well tolerated, efficient and cost effective method with minimal discomfort for the patients. Complete closure rates are high and this approach has become a viable option for ASD management.

Novel uses of intracardiac echocardiography with a phased-array imaging catheter

A newer phased-array ultrasound imaging catheter (AcuNav, Siemens, Moutainview, Calif) provides comprehensive anatomic and physiologic data during cardiac interventions. The role of this catheter in percutaneous closure procedures, transseptal ablative procedures, and valvular interventions has been reported. We describe an expanded role of intracardiac echocardiography using AcuNav imaging catheter (Siemens) in 2 clinical situations.

Catheter-based intracardiac echocardiography in the interventional cardiac laboratory

Recent advances in technology have engendered a renewed enthusiasm in the use of intracardiac echocardiography (ICE) to guide and assess cardiac interventions. AcuNav is a phased-array sector imaging probe equipped with color and spectral Doppler capabilities. Previous-generation imaging catheters yielded unfamiliar limited-depth radial images with no flow information. Current imaging technology such as the AcuNav has not only consolidated the role of ICE but opened newer applications in the interventional laboratory. ICE has clear advantages over transesophageal echocardiography as the imaging modality of choice in the cardiac catheterization and electrophysiological laboratories. We review the technical evolution of ICE and describe the expanded utility of the AcuNav imaging catheter during cardiac interventions.

Intracardiac echocardiography during transcatheter interventions for congenital heart disease

Although transesophageal echocardiography is often used for guidance during transcatheter interventions, few data exist regarding the use of the newer modality of intracardiac echocardiography. This brief report summarizes our single center experience using intracardiac echocardiographic guidance during transcatheter interventional procedures for congenital heart disease.

Use of Intracardiac Echocardiography to Guide Catheter Closure of Atrial Communications

Intracardiac echocardiography (ICE) is slowly replacing transesophageal echocardiography as the preferred imaging tool to guide device closure of atrial septal defects and patent foramen ovale. This article is a brief review of the literature related to ICE, the technical aspects ICE imaging, techniques for obtaining the standard views, and the future directions of this methodology.

Invasive echocardiography: the use of catheter imaging by the interventional cardiologist

Ultrasound imaging is frequently used for diagnostic purposes or guidance during procedures in the pediatric and congenital cardiac catheterization laboratory. As new imaging modalities emerged, many interventional cardiologists rather than noninvasive specialists are now performing the ultrasound imaging as part of the catheterization. The focus of this discussion will be to detail the technique and application of echocardiography by the interventional cardiologist.

Anatomic and hemodynamic imaging using a new vector phased-array intracardiac catheter

BACKGROUND

We used a new vector, phased-array intracardiac catheter (AcuNav) with complete 2-dimensional imaging and Doppler capabilities to describe a systematic approach for a detailed anatomic and hemodynamic cardiac assessment.

METHODS

In 14 dogs, the intracardiac echocardiographic catheter was inserted through an 11F venous access and placed in the right side of the heart to perform a comprehensive ultrasound examination of the heart.

RESULTS

Imaging was successful in all dogs. All 4 cardiac chambers and valves were imaged clearly in multiple orientations. Additional structures seen included the vena cavae, coronary sinus, right and left appendages, interarterial septum, coronary arteries, and all 4 pulmonary veins. Intra-abdominal structures, such as the aorta, liver, and hepatic veins were also visualized. A complete Doppler examination of intracardiac and paracardiac flows was also possible.

CONCLUSION

AcuNav is a unique intracardiac imaging device, which allows comprehensive structural and functional cardiac assessment.

Catheter-based interventions guided solely by a new phased-array intracardiac imaging catheter: in vivo experimental studies

BACKGROUND

Intracardiac echocardiography (ICE) has had useful but limited use during interventional procedures because of technologic limitations. We used a novel phased-array ICE device (AcuNav) with 2-dimensional sector imaging and full Doppler capability to see whether it could guide cardiac interventions without fluoroscopy.

METHODS

Twelve dogs were studied, and we performed atrial septostomy, tricuspid, and pulmonary valve disruption using only ICE. Preinterventional and postinterventional anatomic and hemodynamic data were noted.

RESULTS

All attempts were successful in the placement of the ICE catheter (100%). We attempted septostomy on 11 dogs and were successful 8 times (73%). Tricuspid valve disruption and balloon dilatation were performed successfully on 5 dogs (100%). We attempted pulmonary valve disruption on 4 dogs and could always correctly place the guidewire (100%). We performed pulmonary valve balloon dilatation on one dog (25%). A comprehensive echocardiographic examination was always possible.

CONCLUSION

This new ICE device can guide interventions without fluoroscopy. However, further studies are needed to evaluate whether it can replace fluoroscopy.