View video of the Parachute device implantation that accompanies this article.
The aim of this paper is to describe a typical case history of a patient, which is presented with individual steps during device implantation. The acute hemodynamic changes after Parachute® Ventricular Partitioning Device (CardioKinetix, Inc.) implantation in a small subset of patients are also demonstrated.
Myocardial infarction is frequently followed by left ventricular remodeling, heart failure and increased long-term morbidity and mortality.1-6 As a consequence of myocardial infarction, the left ventricle (LV) can initiate a process of pathologic remodeling, which leads to increasing abnormal wall motion, myocardial thinning and an elongation of the affected region. Geometrical changes of the infarcted area increase the wall stress between the infarct and the normal myocardium. To compensate the abnormal wall motion, the left ventricle increases its volume. The larger volume leads to elevated filling pressures and stiffening of the ventricular walls.6-10 The consequence is a progressive left ventricular dilatation and systolic dysfunction.
Therapies to reverse this pathologic left ventricular remodeling have shown to improve the left ventricular systolic function and the outcome in these patients. Besides pharmacological intervention, left ventricular aneurysms as a consequence of pathological remodeling can lead in many patients to a progressive left ventricular dilatation due to increased wall stress. Thus, for many years, surgical aneurysmectomy was the only solution to decrease the size of the ventricular cavity.11-15 The aim was usually the exclusion of the infarcted wall to decrease end-diastolic volumes, thereby decreasing myocardial work and wall stress and to receive an immediate hemodynamic benefit. But despite clinical success in many patients, mortality displayed rather high and unacceptable rates, with an operative mortality of 7.7% to 17.8% and a five-year survival rate of 60%.16,17
As opposed to surgical endoventriculorrhaphy and aneurysmectomy with the need of thoracotomy, cardiopulmonary bypass and cardioplegia, the Parachute® Ventricular Partitioning Device can be implanted via a percutaneous catheter approach under conscious sedation. This percutaneous ventricular restoration device (Figure 1) effectively excludes the damaged muscle, thereby leading to an isolation of the non-functional muscle from the functional part.18,19 Prior to device implantation, the screening comprises of a clinical examination and assessment of the patient’s overall condition, including an echocardiogram and a cardiac CT scan to evaluate the
geometry of the left ventricle. In this regard, regional wall motion abnormalities, global left ventricular function, and the absence of significant mitral regurgitation seems to be of major importance. The CT scan is also necessary to understand which size of the Parachute® device is needed. It is also important to identify anatomical and pathomorphological structures (e.g., pseudo cords, calcification in the landing zone) that might significantly impact implantation success.
The device is currently available in four sizes: 65 mm, 75 mm, 85 mm and 95 mm. It is distributed with a guide catheter (available in 14 Fr and 16 Fr) and a delivery system. In the future, a steerable catheter will be introduced to enhance the accuracy and ease of use during device implantation. The Parachute® device is comprised of a fluoropolymer membrane stretched over a nitinol frame. The nitinol frame is important to support torsional contraction and optimize LV outflow ejection. Device deployment into the apex of the left ventricle is facilitated by a radiopaque flexible foot, which separates the non-contractile damaged myocardium from the contractile, healthy myocardium. During the final steps, the Parachute® device has to be expanded by a compliant balloon located proximal to a screw connector, which is subsequently released using a distal screw mechanism.
An interventional cardiologist conducted patient selection. All patients had multiple referrals for heart failure to our institution. A transthoracic echocardiogram (TTE) was obtained and all patients were assessed for anteroapical wall motion abnormalities during left heart catheterization. Finally, a cardiac multislice CT was performed for anatomical sizing purpose. Implantation was guided by left ventricular angiography to assess if the Parachute® device position was accurate and to search for possible residual leaks between the walls of the LV and the device. Before and after implantation, invasive hemodynamic measurements were performed in all patients to assess acute hemodynamic changes. A Swan-Ganz catheter was placed into the pulmonary artery, and a pigtail catheter was placed in the LV. Measurements of the systolic, diastolic and mean pulmonary artery pressure (PAPsyst, PAPdiast, PAPmean), pulmonary capillary wedge pressure (PCWP), right atrium pressure (RA), cardiac output (CO), cardiac index (CI), stroke volume (SV), heart rate (HR), left ventricular end-diastolic and systolic pressure (LVEDP, LVESP), systolic, diastolic and mean aortic pressure (AOsyst, AOdiast, AOmean) were taken in all patients.
The first treated patient was a 67-year-old man who had a myocardial infarction in December 2010 with PCI of the left anterior descending artery (LAD). Over subsequent years he developed an apical aneurysm. Prior stenting was done of the circumflex artery in 1997, and LAD/D1 bifurcation in August 2010. Subsequently, he was treated by coronary artery bypass grafting with the left internal mammary artery to the LAD in February 2011. In addition, he received an implantable cardioverter-defibrillator (ICD) in June 2012 for primary prevention of sudden cardiac death.
On admission, he complained about dyspnea during slight exertions (New York Heart Association class III) without any signs of angina pectoris. Echocardiography revealed an ejection fraction (EF) of 25%, an anteroseptal and apical aneurysm, without hypertrophy of the left ventricle. The left ventricular end-diastolic diameter (LVEDD) was 61 mm, and a mild diastolic dysfunction was present. There was no significant mitral regurgitation. In the CT scan, no calcifications or thrombus were found within the apex. Besides his cardiac past medical history, he suffered from bronchial asthma, sleep apnea, and a chronic pain syndrome due to chondrosis of his cervical vertebral column. The implantation of a Parachute® device (85 mm) was successfully performed within 39 min, fluoroscopy time 17 min (see individual steps of implantation in Figure 2). The angiographic assessment of the EF prior to intervention was 28% and increased to 41% after implantation. The end-diastolic volume (EDV) decreased from 147 ml to 107 ml as well as the end systolic volume (ESV) from 106 to 62 ml, respectively. The angiographic measurements were slightly smaller when compared to the CT scan before implantation (EDV 171 ml, ESV 108 ml). In addition, the CT scan revealed a higher stroke volume (62 ml) and LVEF (37%) at baseline compared to the angiographic and echocardiographic data, indicating some limitations with each diagnostic method when used in this particular subset of patients. The invasive assessment (right heart catheterization) of the cardiac output showed an increase from 3.35 l/min to 4.1 l/min as well as a gain in cardiac index from 1.9 l/min/m2 to 2.4 l/min/m2. There was an increase in the stroke volume by 30%, from 65 ml to 85 ml, while the HR, PAP, PCWP and systemic arterial pressure remained essentially unchanged. Most importantly, the basal segments of the heart showed an increase in contractility after implantation, reinforcing the concept of aneurysm exclusion from the circulation. The post-implantation course was uneventful. The patient was discharged on dabigatran 150 mg twice daily in addition to his previous heart failure medications. During follow-up, the patient showed an improved functional capacity at six months.
Overall, eight patients were implanted between September 2012 and March 2013. All procedures were done percutaneously via the femoral artery after preclosure with a ProStar® XL 10 Fr (Abbott Vascular). All devices were implanted either through a 14 Fr or 16 Fr guide catheter. In all patients, the collapsed Parachute® device was successfully advanced retrograde through the guide catheter over the aortic valve and positioned in the LV apex. In a single patient, the device had to be removed with a snare from the left ventricle, due to dislocation from the proper landing zone. In retrospect, this patient was a suboptimal candidate due to a prominent pseudo cord, which was close to the targeted landing zone. In all remaining patients, repeated LV angiograms showed appropriate positioning with only minor leaks, which were present in two patients. After implantation we found a significant increase in three parameters: stroke volume, cardiac output, and cardiac index. The SV had an average increase in 35.91% (+14.61 ml). Also, the CO had an increase in 30.55% (+0.8 l/min), while the CI increased by 32.32% (+0.46 l/min/m2) (Figure 3). The HR (-1.65 bpm), PCWP (+2.26 mmHg), PAPmean (+6.3 mmHg) and RA (+4.36 mmHg) remained essentially unchanged. One patient did not hemodynamically benefit from the device. The reason for this remains unclear. The procedure was terminated after successful closure of the ProStar in all patients. There were no vascular complications and no other adverse events during the hospital course reported in all patients.
Due to the unfavorable natural history of patients with medically treated ischemic heart failure and high mortality rates, especially in those with progressive LV remodeling,20,21 additional treatment strategies are strongly warranted. In this regard, excluding the primary dysfunctional (akinetic or dyskinetic) area of myocardium might be an interesting concept to improve clinical outcome.The case and the hemodynamic results of the seven treated patients are a subset of patients that have been treated within the PARACHUTE trial. The data demonstrate the feasibility and acute hemodynamic efficacy of percutaneous LV partitioning in congestive heart failure with a prior anterior MI. The Parachute® device was safely and successfully implanted in seven out of eight patients. As stated previously, one device had to be removed after improper landing, which was performed without any sequelae. Thus, preimplantation anatomical screening remains crucial for device success as with any other medical device. The study also demonstrates the acute improvement in hemodynamics after percutaneous ventricular partitioning. As expected, implantation of a Parachute® device resulted in an immediate reduction in LV volumes and an increase in LV ejection fraction. Certainly, it might be argued that LVEF is not the correct measure to understand the hemodynamic changes after device implantation. Therefore, we carefully assessed the invasive hemodynamic changes before and after device implantation. In this regard, we found basically unchanged global hemodynamics, with a major exception — the forward stroke volume increased on average by 36%. These changes were associated with improvements in NYHA functional class ranking, quality of life, and exercise capacity (preliminary data, some data is pending due to ongoing data collection within the study). Despite this small number of patients, a definite positive conclusion regarding the device efficacy can be drawn since a placebo effect on acute hemodynamics can be excluded. This data adds additional evidence to the PARACHUTE study, which demonstrated the ventricular partitioning device to be relatively safe and of potential benefit in patients with heart failure due to prior anterior myocardial infarction.22 Our observations are in line with previously published data, demonstrating device efficacy in this specific patient population.Disclosures: Drs. Schmidt, Frerker, Thielsen, and Kuck have no conflicts of interest to report. Dr. Schäfer reports he is a paid consultant of CardioKinetix.
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