Ryan J. Williams

Melody Valve Implant Within Failed Bioprosthetic Valves in the Pulmonary Position A Multicenter Experience

Background—Transcatheter pulmonary valve implantation using the Melody valve has emerged as an important therapy for the treatment of postoperative right ventricular outflow tract dysfunction. Melody-in-bioprosthetic valves (BPV) is currently considered an off-label indication. We review the combined experience with transcatheter pulmonary valve implantation within BPVs from 8 centers in the United States and discuss technical aspects of the Melody-in-BPV procedure. Methods and Results—A total of 104 patients underwent Melody-in-BPV in the pulmonary position at 8 US centers from April 2007 to January 2012. Ten different types of BPVs were intervened on, with Melody valve implantation at the intended site in all patients. Following Melody valve implant, the peak right ventricle-to-pulmonary artery gradient decreased from 38.7±16.3 to 10.9±6.7 mm Hg (P<0.001), and the right ventricular systolic pressure fell from 71.6±21.7 to 46.7±15.9 mm Hg (P<0.001). There was no serious procedural morbidity, and no deaths related to the catheterization or implant. At a median follow-up of 12 months (1–46 months), no patients had more than mild regurgitation, and 4 had a mean right ventricular outflow tract gradient ≥30 mm Hg. During follow-up, there were 2 stent fractures, 3 cases of endocarditis (2 managed with surgical explant), and 2 deaths that were unrelated to the Melody valve. Conclusions—Transcatheter pulmonary valve implantation using the Melody valve within BPVs can be accomplished with a high rate of success, low procedure-related morbidity and mortality, and excellent short-term results. The findings of this preliminary multicenter experience suggest that the Melody valve is an effective transcatheter treatment option for failed BPVs.

Two-Dimensional and Doppler Echocardiography Reliably Predict Severe Pulmonary Regurgitation as Quantified by Cardiac Magnetic Resonance

BACKGROUND The grading of pulmonary regurgitation (PR) severity by two-dimensional (2D) and Doppler echocardiography is not standardized. Cardiovascular magnetic resonance imaging is the clinical gold standard for PR quantification. The purpose of this study was to determine the best 2D and Doppler echocardiographic predictors of severe PR. METHODS Thirty-six patients with tetralogy of Fallot or pulmonary valve stenosis with prior pulmonary valvuloplasty or transannular or subannular patch repair underwent 2D and Doppler echocardiography and cardiovascular magnetic resonance. Two-dimensional and Doppler echocardiographic measurements used to predict severe PR included diastolic flow reversal in the main or branch pulmonary arteries, PR jet width > or = 50% of the pulmonary annulus, PR pressure half-time < 100 ms, and PR index < 0.77. RESULTS With the exception of PR index, all indices were significant independent predictors of severe PR. The best univariate predictor of severe PR was branch pulmonary artery diastolic flow reversal. CONCLUSION Two-dimensional and Doppler echocardiography reliably identified severe PR in this cohort.

Arrhythmia Recurrence in Adult Patients with Single Ventricle Physiology Following Surgical Fontan Conversion: Arrhythmia Recurrence Following Fontan Conversion

OBJECTIVES To evaluate the incidence of atrial tachy-arrhythmia (AT) recurrence following conversion from right atrial-pulmonary artery (RA-PA) Fontan to total cavopulmonary connection (TCPC) in adults. BACKGROUND AT is a recognized sequel of Fontan palliation, especially in RA-PA Fontans, and is associated with significant morbidity. While catheter ablation achieves fairly reliable short-term success with low morbidity, conversion to TCPC with arrhythmia surgery is a highly effective treatment option for the classical Fontan patients with incessant AT. METHODS Single center retrospective review. RESULTS Twenty-seven adults underwent Fontan conversion from RA-PA to TCPC, mostly for AT indications (n = 24). Nine (33%) underwent conversion to a lateral tunnel (LT) and 18 (67%) to an extracardiac (EC) Fontan. Two patients died <30 days post-operatively. Both had liver failure and had been turned down for cardiac/liver transplantation. In-hospital complications occurred in 15/27 patients (55%), including recurrence of AT requiring cardioversion in six patients (22%) and persistent pleural effusions in 4 (15%). Mean follow-up was 4.2 years (range 3 months-14 years). Functional capacity improved from mean New York Heart Association (NYHA) class 1.8 pre-conversion to 1.2 post-conversion (P= 0.008). Twenty-one patients had concomitant arrhythmia surgery (MAZE in 12 patients with IART and Cox-MAZE in nine patients with A-Fib +/- IART). Of these, 3/21 (14%) had AT recurrence >3 months following conversion. CONCLUSIONS Conversion from RA-PA Fontan to TCPC, with arrhythmia surgery, decreases AT recurrence and improves functional capacity. The risk of peri-operative mortality is highest in patients with cirrhosis. AT recurred in 14% of patients.

Novel techniques of mechanical circulatory support for the right heart and Fontan circulation

BACKGROUND Currently available ventricular assist devices are designed primarily for use in patients with left sided heart failure. This study evaluated the efficacy of the Jarvik 2000 ventricular assist device (VAD) as a pulmonary pump to power a Fontan circuit in a large animal model. METHODS Without the use of cardiopulmonary bypass, Fontan circulations were surgically created in 4 pigs (50 kg) using synthetic grafts from the inferior and superior vena cavas to the main pulmonary artery. Subsequently, the VAD was implanted within the common Fontan graft to provide a pulmonary pump. Direct chamber pressures and epicardial Doppler images were taken during the various phases of the experiment. Heart rate, femoral artery blood pressure, oxygen saturation, and aortic flow rate were continuously recorded. The outflow cannula of the VAD was then partially banded by 50% and then 75% to mimic increased afterload. RESULTS Fontan and VAD implantation was successfully performed in all 4 animals. Arterial pressure and aortic flow decreased dramatically with institution of the Fontan but were restored to baseline upon activation of the VAD. The pressure within the systemic venous circulation rose precipitously with institution of the Fontan circulation and improved appropriately with activation of the VAD. Adequate perfusion was maintained during increased afterload. CONCLUSIONS An axial flow VAD can restore normal hemodynamics and cardiac output when used as a pulmonary pump in a Fontan circulation. A VAD can rescue a failing Fontan as a bridge to transplant or recovery, even in the setting of high pulmonary resistance.

Usefulness of Serum Brain Natriuretic Peptide to Predict Adverse Events in Patients With the Eisenmenger Syndrome

The aim of this study was to evaluate the prognostic value of brain natriuretic peptide (BNP) in outpatients with the Eisenmenger syndrome (ES). BNP is often elevated in patients with cyanotic congenital heart disease. The clinical utility of BNP in patients with cyanotic congenital heart disease and the ES has not been clearly delineated. Records of adults with ES who had undergone serum BNP measurement were reviewed. The primary end point was death or heart failure admission. Fifty-three patients were included, with 15 patients (28%) meeting the primary end point (death in 7, heart failure hospitalization in 8). Mean and median baseline BNP in patients meeting the primary end point were 322 ± 346 and 179 pg/ml, compared to 100 ± 157 and 41 pg/ml in those not meeting the primary end point (p = 0.0029). A Cox proportional-hazards model using baseline BNP between the 2 groups yielded a hazard ratio of 1.84 (95% confidence interval [CI] 1.19 to 2.85, p = 0.006). The relative risk for baseline BNP level >140 pg/ml was 4.62 (95% CI 1.80 to 11.3, p = 0.008). Patients who met the primary end point increased their BNP levels by 42.5 pg/ml per year (95% CI 12.09 to 72.95, p = 0.006) compared to 7.2 pg/ml per year (95% CI 2.01 to 12.47, p = 0.007) in patients who did not meet the primary end point. In conclusion, elevated BNP levels are predictive of death or heart failure admission in patients with the ES. A serum BNP level >140 pg/ml is a useful tool in identifying high-risk patients.

EFFICACY OF ENDOTHELIN BLOCKADE IN ADULTS WITH FONTAN PHYSIOLOGY

OBJECTIVE Phosphodiesterase-5 inhibitors have shown to improve cardiac output and functional capacity in Fontan patients. We sought to test the efficacy and safety of endothelin blockade with bosentan in adult patients with Fontan physiology. DESIGN Ten patients were enrolled and seven patients completed this single-center open-label clinical trial. Patients were treated with bosentan for 4 months. Cardiac magnetic resonance imaging (MRI), 6-minute walking distance (6MWD), brain natriuretic peptide, and New York Heart Association functional class were compared before and after treatment using paired t-test. RESULTS The 6MWD improved by 73 m, from a mean of 435 m (standard deviation [SD] = 92, standard error [SE] = 35) to 508 m (SD = 93, SE = 35) (P = .03). MRI resting aortic flow increased from 3.3 L/minute (SD = 1.27, SE = 0.73) to 4.4 L/minute (SD = 0.9, SE = 0.54) (P = .03). New York Heart Association class was unchanged in three patients, improved in three patients and worsened in one patient. Brain natriuretic peptide, aspartate aminotransferase, and alanine aminotransferase did not change significantly. Of the three patients with elevated baseline bilirubin, two normalized at the completion of the study, while the other was unchanged. Mean duration of therapy was 4.1 ± 0.51 months. Three adverse advents occurred. One patient complained of fatigue and chest pain after 87 days and withdrew from the study. After extensive workup, it was determined that her symptoms were not related to treatment. The second patient suffered palpitations and fatigue after 75 days; no concerning arrhythmias were identified and symptoms improved with increased antiarrhythmic dose. The third patient developed fatigue on therapy and decided to stop therapy; fatigue improved following drug discontinuation. There were no deaths or hospitalizations. CONCLUSIONS In this cohort of adult patients with Fontan physiology, endothelin blockade with bosentan resulted in improved 6MWD and MRI-derived resting cardiac output, suggesting a positive effect on pulmonary vascular resistance and pulmonary blood flow. Bosentan was well tolerated and hepatic function was not adversely affected.

Thin film nitinol covered stents: design and animal testing.

Interventionalists in many specialties have the need for improved, low profile covered stents. Thin films of nitinol (<5–10 microns) could be used to improve current covered stent technology. A “hot target” sputter deposition technique was used to create thin films of nitinol for this study. Covered stents were created from commercially available balloon-inflatable and self-expanding stents. Stents were deployed in a laboratory flow loop and in four swine. Uncovered stent portions served as controls. Postmortem examinations were performed 2–6 weeks after implantation. In short-term testing, thin film nitinol covered stents deployed in the arterial circulation showed no intimal proliferation and were easily removed from the arterial wall postmortem. Scanning electron microscopy showed a thin layer of endothelial cells on the thin film, which covered the entire film by 3 weeks. By contrast, significant neointimal hyperplasia occurred on the luminal side of stents deployed in the venous circulation. Extremely low-profile covered stents can be manufactured using thin films of nitinol. Although long-term studies are needed, thin film nitinol may allow for the development of low-profile, nonthrombogenic covered stents.

Efficacy and Safety of Bosentan in Adults with Simple and Complex Eisenmenger's Syndrome

BACKGROUND   Eisenmengers syndrome (ES) is associated with decreased longevity and reduced functional capacity. Targeted pharmacologic therapies improve functional capacity and survival in these patients. We sought to compare the response of patients with simple vs. complex ES following initiation of bosentan. METHODS   ES patients with a history of bosentan use were identified by chart review. Simple ES was defined as ES associated with atrial septal defect, ventricular septal defect, or patent ductus arteriosus. Complex ES consisted of patients with truncus arteriosus and single ventricle congenital heart disease. Six-minute walking distance (6MWD), maximal oxygen consumption (VO(2) max), brain natriuretic peptide (BNP), and resting oxygen saturation were compared between simple and complex ES patients before and after bosentan treatment. RESULTS   Twenty-four patients were included (11 simple, 13 complex). Resting oxygen saturation, 6MWD, VO(2) max, and BNP were not significantly different between the two groups prior to bosentan initiation. Ten patients received bosentan monotherapy, and bosentan was used in combination with sildenafil in 13 (five simple, eight complex). One patient received bosentan with iloprost. Mean duration of therapy was 38 ± 14 months in the simple group and 40 ± 8.1 months in the complex group (P= NS). Posttreatment, 6MWD increased from 274 ± 135 m to 326 ± 106 m in simple ES patients (P= .32). 6MWD in patients with complex ES increased from 332 ± 51 m to 364 ± 109 (P= .028). VO(2) max improved from 13.4 ± 3.8 to 17 ± 6 (P= .54) in the simple group, while VO(2) max in the complex group improved from 12.7 ± 2.3 to 15.5 ± 2.2 (P= .17). There was minimal change in BNP or resting oxygen saturation between the groups. CONCLUSIONS   Treatment with bosentan is both safe and effective in patients with both simple and complex forms of ES.

Evaluating piezoelectric hydraulic pumps as drivers for pulsatile pediatric ventricular assist devices

Piezohydraulic pumps are high power density motors, which can be theoretically miniaturized with minimal loss in power output. The feasibility of using piezohydraulic pumps in pulsatile pediatric ventricular assist devices is presented in this study. A theoretical analysis is presented to calculate the piezohydraulic pump dimensions needed to meet flow and pressure requirements. In addition, an existing piezohydraulic pump was incorporated into a ventricular assist device driver to drive a pulsatile pediatric 30-mL stroke ventricular assist device as a proof of concept. The driver was tested at heart rates ranging from 50 to 110 beats per minute in an in vitro mock circulation to characterize its performance. The maximum drive pressure was 33 kPa with a peak flow rate of 6 L/min against a 10-kPa back pressure. The maximum mean flow rate from the ventricular assist device outlet was 3 L/min at 100 beats per minute operation. These results compare well to commercially available systems that output between 25 and 40 kPa drive pressure and flows between 0 and 10 L/min against 10–16 kPa pressures.

Radiographic appearance of pediatric cardiovascular transcatheter devices

The treatment of congenital heart disease has been revolutionized by the availability of transcatheter devices. These advances in interventional pediatric cardiology require that both treating physicians and radiologists develop a more thorough understanding of the appearance of these devices on chest radiographs. Furthermore, recognition of appropriate versus inappropriate placement of transcatheter devices is essential to the care of patients with congenital heart disease. Knowledge of the radiographic appearance of devices used by interventional pediatric cardiologists can allow a radiologist to make better clinical assessments and detect possible complications given a limited clinical history.