Bioprosthetic valve oversizing is associated with increased risk of valve thrombosis following TAVR

BACKGROUND

Hypoattenuating leaflet thickening (HALT), the radiographic manifestation of transcatheter heart valve thrombosis, is commonly identified following transcatheter aortic valve replacement (TAVR) and associated with increased risk of stroke and structural valve deterioration. While anticoagulation effectively resolves HALT, routine use remains controversial. We aimed to identify hemodynamic, anatomic, and comorbid predictors of HALT.

METHODS

We evaluated consecutive patients with severe aortic stenosis who underwent TAVR with Edwards SAPIEN 3 bioprosthesis at a single center between June 1, 2018 and October 30, 2019. Patients on anticoagulation and those receiving valve-in-valve were excluded. Clinically driven computed tomography (CT) imaging was performed to assess for HALT at the discretion of the treating valve team.

RESULTS

A total of 78 patients with a mean age of 78 ± 10 years and STS risk score 5.5 ± 3.3% were analyzed. HALT was identified in 11 (14.1%) patients. Compared to controls, those with HALT had smaller annular areas, 435 ± 57 mm² vs. 489 ± 79 mm² (p = .032), but received comparable size valves. In multivariate regression, valve oversizing by more than 20% was associated with increased risk of HALT, OR 23.5, 95% CI 2.5-223, (p = .006). After initiation of anticoagulation, patients with HALT had similar rates of stroke, major bleeding, and all-cause mortality out to an average of 243 days.

CONCLUSIONS

In this pragmatic study of patients undergoing TAVR with SAPIEN 3 valves, we report the novel finding that oversizing by more than 20% was independently associated with increased risk of HALT. These findings warrant confirmation in larger and prospective trials.

Transcatheter Aortic Valve Replacement in Low-risk Patients With Bicuspid Aortic Valve Stenosis

Importance

The outcomes of transcatheter aortic valve replacement (TAVR) in low-risk patients with bicuspid aortic valve stenosis have not been studied in a large scale, multicentered, prospective fashion.

Objective

To evaluate the procedural safety, efficacy, and 30-day outcomes of TAVR in patients with bicuspid aortic stenosis at low surgical risk.

Design, Setting, and Participants

The Low Risk Bicuspid Study is a prospective, single-arm trial study with inclusion/exclusion criteria developed from the Evolut Low Risk Randomized Trial. Follow-up is planned for 10 years. Patients underwent TAVR at 25 centers in the United States who were also participating in the Evolut Low Risk Randomized Trial from December 2018 to October 2019. Eligible patients had severe bicuspid aortic valve stenosis and met American Heart Association/American College of Cardiology guideline indications for aortic valve replacement.

Interventions

Patients underwent attempted implant of an Evolut or Evolut PRO transcatheter aortic valve, with valve size based on annular measurements.

Main Outcomes and Measures

The prespecified primary end point was the incidence of all-cause mortality or disabling stroke at 30 days. The prespecified primary efficacy end point was device success defined as the absence of procedural mortality, the correct position of 1 bioprosthetic heart valve in the proper anatomical location, and the absence of more than mild aortic regurgitation postprocedure.

Results

A total of 150 patients underwent an attempted implant. Baseline characteristics include mean age of 70.3 (5.5) years, 48.0% female (n = 72), and a mean Society of Thoracic Surgeons score of 1.4 (0.6%). Most patients (136; 90.7%) had Sievers type I valve morphology. The incidence of all-cause mortality or disabling stroke was 1.3% (95% CI, 0.3%-5.3%) at 30 days. The device success rate was 95.3% (95% CI, 90.5%-98.1%). At 30 days, the mean (SD) AV gradient was 7.6 (3.7) mm Hg and effective orifice area was 2.3 (0.7) cm2. A new permanent pacemaker was implanted in 22 patients (15.1%). No patients had greater than mild paravalvular leak.

Conclusions and Relevance

Transcatheter aortic valve replacement in low-surgical risk patients with bicuspid aortic valve stenosis achieved favorable 30-day results, with low rates of death and stroke and high device success rate.

Trial Registration

ClinicalTrials.gov Identifier: NCT03635424.

Meta-Analysis of Secondary Prevention of Cryptogenic Stroke

BACKGROUND

Cryptogenic stroke and embolic stroke of undetermined source (ESUS) are a frequently encountered categories of ischemic stroke with an uncertain cause.

METHODS

We analyzed all randomized clinical trials (RCTs) that evaluated antithrombotic therapy and patent foramen ovale (PFO) closure in cryptogenic stroke and/or ESUS. We calculated aggregate hazard ratios (HRs) using direct and network meta-analysis. The primary outcome was recurrent ischemic stroke.

RESULTS

Ten RCTs with a total of 16,876 patients, randomizing 32,143 patient-years of follow-up (mean age 61.2 ± 13.5 with 39.2% female) were identified. Anticoagulation therapy was associated with significantly reduced recurrent ischemic stroke compared with antiplatelet therapy (HR = 0.66; [95% confidence interval (CI) = 0.47-0.94]). Meta-regression analysis showed significantly reduced recurrent stroke with longer duration of therapy, and significantly increased events with advanced age. Significant interactions were observed based on the presence of PFO, stroke type, and anticoagulant used. There were no significant differences with regard to the composite ischemic outcome, transient ischemic attack, any death, major bleeding, or intracranial bleeding. In the network meta-analysis, compared to antiplatelet therapy, warfarin (HR = 0.31; [95% credible interval (CrI) = 0.12-0.68]) and PFO closure (HR = 0.14; 95% CrI = 0.05-0.31]) were associated with significantly reduced recurrent ischemic stroke. In rank order, PFO closure was associated with the best outcome, followed by warfarin.

CONCLUSIONS

Among patients with cryptogenic stroke, anticoagulation therapy, as compared with antiplatelet therapy is associated with lower rate of recurrent stroke. The small sample size and high heterogeneity with regards to bleeding outcomes require further large trials. In patients with PFO, closure and warfarin are associated with the lowest rates of recurrent stroke.

Meta-analysis of bivalirudin versus heparin in transradial coronary interventions

OBJECTIVES

We sought to evaluate the efficacy and safety of bivalirudin versus heparin in patients with coronary artery disease undergoing transradial artery coronary intervention (TRI).

BACKGROUND

Bivalirudin and radial artery access are independently associated with improved cardiovascular outcomes. However, data supporting a strategy of combining both to achieve additive improvements in cardiovascular outcomes provide conflicting results.

METHODS

A systematic search was performed to identify randomized controlled trials (RCTs) of bivalirudin, in which vascular access sites were reported. The primary outcome was net adverse clinical events (NACE) at 30 days. Secondary outcomes were long-term NACE, short-, and long-term major adverse cardiovascular events, all-cause mortality, myocardial infarction, unplanned revascularization, stent thrombosis, and major bleeding.

RESULTS

We identified 10 RCTs, including 16,328 patients who underwent TRI (mean age 64.6 ± 15.7 years, 72.5% male). Bivalirudin use was associated with decreased 30-day NACE compared with heparin (6.3 vs. 7.4%; risk ratio [RR] = 0.87; 95% confidence interval [CI] = 0.76-0.99; p = .04; number needed to treat = 91). No significant interactions were observed based on clinical presentation, administration of P2Y₁₂ inhibitors, or glycoprotein IIb/IIIa-receptor inhibitors (GPI) use. There were no significant differences between groups in any prespecified secondary outcomes. There was, however, a significant reduction of major bleeding in the bivalirudin group compared with heparin when used in combination with routine GPI (RR = 0.41; 95% CI = 0.19-0.90; p = .03).

CONCLUSIONS

Among patients undergoing TRI, use of bivalirudin was associated with significantly reduced 30-day NACE compared with heparin. There was no significant difference in long term NACE, ischemic, or bleeding events compared with heparin.

Meta-Analysis Comparing Complete Versus Infarct-Related Artery Revascularization in Patients With ST-Elevation Myocardial Infarction and Multivessel Coronary Disease

A strategy of complete revascularization (CR) versus infarct-related artery revascularization (IRA) in patients with ST-elevation myocardial infarction (STEMI) continues to be a subject of debate. We performed an updated meta-analysis to compare the 2 strategies. Outcomes of interest included major adverse cardiovascular events (MACE), cardiovascular mortality, all-cause mortality, stroke, repeat revascularization, myocardial infarction, and contrast-induced nephropathy. Ten randomized trials including 7,423 patients (CR = 3,574 and IRA = 3,849), with a follow-up of 2.0 ± 0.8 years were included. There was a significant reduction in MACE with CR versus IRA (10.7% vs 18.6%, relative risk [RR] 0.64, 95% confidence interval [CI] 0.51 to 0.81, p = 0.002, I² = 66%), with higher risk reduction with immediate versus stages revascularization (RR 0.40, 95% CI 0.32 to 0.5 vs RR 0.69, 95% CI 0.54 to 0.89, P-interaction = 0.002). Complete revascularization was associated with lower rates of repeat revascularization (4.0% vs 11.7%, RR 0.44, 95% CI 0.28 to 0.70, p <0.0001, I² = 81%), and a nonsignificant trend toward lower cardiovascular mortality (2.8% vs 3.7%, RR 0.78, 95% CI 0.60 to 1.03, p = 0.08, I² = 0%). However, there was no difference between the 2 strategies in all-cause mortality (4.6% vs 4.8%, RR 0.90, 95% CI 0.73 to 1.12, p = 0.36, I² = 0%), myocardial infarction (5.2% vs 6.5%, RR 0.73, 95% CI, 0.58 to 1.08, p = 0.08, I² = 30%), stroke (1.5% vs 1.2%, RR 1.14, 95% CI 0.56 to 2.29, p = 0.33, I² = 14%), or contrast-induced nephropathy (1.6% vs 1.2%, RR 1.35, 95% CI 0.85 to 2.15, p = 0.78, I² = 0%). In conclusion, CR in patients with STEMI is associated with significant reduction in MACE compared with IRA. This reduction is derived mainly by the low rates of repeat revascularization in the CR group.

Meta-Analysis of Transcatheter Aortic Valve Replacement in Low-Risk Patients

PURPOSE

This study evaluated the efficacy and safety of transcatheter aortic valve replacement (TAVR) compared with surgical aortic valve replacement (SAVR) in low surgical risk patients.

METHODS

An electronic database search was conducted for randomized controlled trials (RCTs). We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) using a random-effects model.

RESULTS

Five RCTs were identified with a total of 3,072 patients (mean age 74.5 ± 6.1 and 64.8% male). Compared with SAVR, TAVR was associated with a significantly reduced rate of death or disabling stroke (HR = 0.52; 95% CI = 0.27-0.99; P = .049), atrial-fibrillation (HR = 0.28; 95% CI = 0.18-0.46; P < .01), and post-procedure bleeding (HR = 0.38; 95% CI = 0.31-0.46; P < .01), along with a significantly improved quality-of-life at 1-year. However, TAVR was associated with significantly increased rates of paravalvular leak (HR = 4.09; 95% CI = 1.92-8.69; P < .01) and pacemaker insertion (HR = 2.81; 95% CI = 1.85-4.28; P < .01) compared with SAVR.

CONCLUSION

Among older low-risk patients with severe aortic stenosis, TAVR is associated with a lower rate of death or disabling stroke compared with SAVR. Transcatheter aortic valve replacement is also associated with improved quality-of-life, reduced bleeding and atrial fibrillation, but higher paravalvular leak and pacemaker implantation rates.

Replacing the mitral valve alone does not completely fix the heart!

TMVR for degenerative (stenosis and regurgitation) mitral valve prosthesis (valves and rings) results in immediate and sustainable reduction but not normalization of left atrial pressure. Concomitant comorbid conditions such as left ventricular diastolic dysfunction adversely impact left atrial pressure and should be treated. The long-term impact of postprocedural ASD and patient-prosthesis mismatch need to be systematically evaluated so we develop the appropriate data to guide decision making as more transeptal mitral procedures are being performed.

Hypertension and Aortic Stenosis: A Review

BACKGROUND

Aortic stenosis is a common form of valvular heart disease which often coexists with hypertension. These diseases represent two distinct forms of left ventricular systolic overload and in combination may be associated with disadvantageous left ventricular remodeling, increased mortality and heart failure. The treatment of hypertension in aortic stenosis remains a challenging problem with limited data to guide clinical practice.

METHODS

We performed a comprehensive online literature review to find relevant published literature on the topic of hypertension and aortic stenosis.

RESULTS

In the present manuscript, we review the pathophysiology of aortic stenosis in combination with hypertension and the effects on the left ventricle. We also provide general recommendations for medical therapy for treatment of hypertension in aortic stenosis and review the available data on specific antihypertensive agents in this context.

CONCLUSIONS

Aortic stenosis and hypertension commonly coexist and significantly impact the diagnosis and classification of aortic stenosis severity and symptoms. Treatment of hypertension among patients with severe aortic stenosis can be challenging. Among specific antihypertensive agents studied in this context, ACE-inhibitors are the most well studied.

Early post-approval experience with transcatheter aortic valve replacement in the USA

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is changing the treatment of aortic stenosis. We compared cost and clinical outcomes of TAVR versus surgical aortic valve repair (SAVR) in the real-world setting since USA TAVR approval in 2012.

METHODS

The Nationwide Inpatient Sample (NIS) dataset was analyzed by quarter (June 2012 to December 2014). Patients (>65 years old) undergoing TAVR or SAVR were identified and risk stratified based on APR-DRG Mortality risk score. Outcomes were in-hospital mortality, length of stay (LOS), discharge location, and hospitalization cost.

RESULTS

TAVR cases per quarter increased from 1900 to 5445 over the study period. TAVR patients were older and had more comorbidities (P<0.001). TAVR patients had longer LOS (8 vs. 7 days; P<0.001), were less likely to discharge to home (67% vs. 73%; P<0.001), had higher inpatient mortality (5.5% vs. 0.69%; P<0.001) and overall hospital cost ($ 227,985 vs. $ 148,019; P<0.001) than SAVR patients. On multivariate analysis TAVR was associated with increased cost (β=0.42; P<0.001) and increased mortality (OR=5.228, CI: 3.508-7.791; P<0.001) but not associated with increased LOS (β=0.297; P=0.078) or discharge to facility (OR=1.004, CI: 0.833-1.213; P=0.960). In the last two quarters of 2014 there was no difference between TAVR and SAVR LOS, however TAVR cost did not decrease over the study period.

CONCLUSIONS

TAVR patients represented a sicker population, however LOS and discharge location outcomes were equivalent to SAVR. TAVR remained significantly more expensive across all risk groups and cost did not fall over the course of the study.

Management of Late Paravalvular Leak after Transcatheter Valve Placement in Calcified Mitral Annulus

Mitral annular calcification presents a unique challenge to the surgical and interventional management of mitral valve pathology. Herein are presented the details of an emerging use of transcatheter valve replacement not only to salvage an open operation but also to minimize the important late complications of valve migration, resulting in paravalvular leak (PVL). The valve was initially stabilized with balloon valvuloplasty to prevent further migration; a vascular plug was then used to close the PVL. Teams treating complex valvular pathology with transcatheter technologies should be aware of these pitfalls, and be prepared to manage both early and late complications that may arise after transcatheter interventions. Video 1: Paravalvular leak due to atrial migration of the stent frame. Video 2: Resolution of paravalvular leak.

Everolimus eluting bioresorbable vascular scaffolds; can we absorb the risk in complex PCI?

BVS, as compared with DES, have higher stent thrombosis (ST) rates. BVS may prove reasonable in patients with complex anatomy. Future trials will be necessary to guide clinicians regarding whether BVS are equivalent to DES in patients with noncomplex or complex coronary anatomy.

Trends in hospitalization for takotsubo cardiomyopathy in the United States

BACKGROUND

Takotsubo (or stress induced) cardiomyopathy is characterized by transient left ventricular systolic dysfunction. Recent trends in patient volume, characteristics, and outcomes in the United States are unknown.

METHODS

Using 2007-2012 National Inpatient Sample data, we identified 22,005 adults (≥18 years) with a primary and 31,942 adults with a secondary discharge diagnosis of takotsubo cardiomyopathy (International Classification of Diseases, Ninth Revision, code 429.83) who underwent diagnostic coronary angiography.

RESULTS

During 2007 to 2012, the incidence of takotsubo cardiomyopathy increased over 3-fold: 52/million discharges in 2007 to 178/million in 2012 (P < .001). We found a temporal increase in the prevalence of cardiac arrest, cardiogenic shock, cardiovascular risk factors (diabetes, hypertension), and psychiatric disorders (P trend < .0001 for all). In-hospital mortality was 1.1% and remained unchanged over this period (P = .22). Compared to the primary diagnosis group, mortality in the secondary diagnosis group was higher (1.1% vs 3.2%) and was associated with higher incidence of cardiogenic shock, cardiac arrest, and respiratory failure. Men represent 8% of patients in the primary diagnosis group and 12% in the secondary group. In both groups, men had a higher incidence of shock, cardiac arrest, and respiratory failure. Although their mortality was higher than women in the primary group (3.0% vs 0.9%, adjusted odds ratio 3.85, 1.74-8.51), it was comparable in the secondary group (4.8% vs 3.0%).

CONCLUSIONS

We found a marked increase in the hospitalization for takotsubo cardiomyopathy in the United States in recent years, suggesting higher incidence than prior reports. Although outcomes have remained favorable, there is an increasing burden of cardiovascular and psychiatric disorders in this population with growing cost of care. Risk of mortality is higher in men and in patients with underlying critical illness. The excess mortality in these groups appears to be mediated by greater severity of disease.

Giant saphenous vein graft pseudoaneurysm to right posterior descending artery presenting with superior vena cava syndrome

Saphenous vein grafts (SVG) pseudoaneurysms, especially giant ones, are rare and occur as a late complication of coronary artery bypass grafting. This condition affects both genders and typically occurs within the sixth decade of life. The clinical presentation ranges from an asymptomatic incidental finding on imaging studies to new onset angina, dyspnea, myocardial infarction or symptoms related to compression of neighboring structures. An 82-year-old woman presented with acute onset back pain, dyspnea and was noted to have significantly engorged neck veins. In the emergency department, a chest computed tomographic angiogram with intravenous contrast revealed a ruptured giant bilobed SVG pseudoaneurysm to the right posterior descending artery (RPDA). This imaging modality also demonstrated compression of the superior vena cava (SVC) by the SVG pseudoaneurysm. Coronary angiogram with bypass study was performed to establish the patency of this graft. Endovascular coiling and embolization of the SVG to RPDA was initially considered but disfavored after the coronary angiogram revealed preserved flow from the graft to this arterial branch. After reviewing the angiogram films, a surgical strategy was favored over a percutaneous intervention with a Nitinol self-expanding stent since the latter would have not addressed the superior vena cava compression caused by the giant pseudoaneurysm. Intraoperative transesophageal echocardiogram demonstrated SVC compression by the giant pseudoaneurysm cranial lobe. Our patient underwent surgical ligation and excision of the giant pseudoaneurysm and the RPDA was regrafted successfully. In summary, saphenous vein grafts pseudoaneurysms can be life-threatening and its therapy should be guided based on the presence of mechanical complications, the patency of the affected vein graft and the involved myocardial territory viability.

Impact of anemia on platelet response to clopidogrel in patients undergoing percutaneous coronary stenting

High residual platelet reactivity (HRPR) on clopidogrel is a predictor of recurrent ischemic events in patients undergoing percutaneous coronary interventions (PCI). Significant intraindividual variability in platelet aggregation on repeat testing has been reported. To understand factors contributing to the variability in platelet aggregation testing, we examined clinical and laboratory elements linked to HRPR in 255 consecutive patients tested ≥12 hours after PCI using light transmission aggregometry (LTA) in response to adenosine diphosphate 5 μmol/L and VerifyNow P2Y12 assay (VNP2Y12; Accumetrics). HRPR was defined as >46% residual aggregation for LTA and >236 P2Y12 response units (PRUs) for VNP2Y12. On multivariate analysis the only variable independently associated with HRPR with both LTA and VNP2Y12 was laboratory-defined anemia. Prevalences of HRPR by LTA were 34.3% in anemic patients, 15.6% in patients with normal hemoglobin levels, and 59.8% versus 25.9% by VNP2Y12 (p <0.005 for the 2 comparisons). In a subgroup of 50 patients, testing was done before and after the clopidogrel loading dose. At baseline there were no differences in platelet aggregation with either assay; however, absolute decrease in reactivity after the clopidogrel load was significantly less in anemic patients compared to patients with normal hemoglobin (change in residual aggregation by LTA 15.8 ± 5.8% vs 28.8 ± 3.2%, p <0.05; change in PRU by VNP2Y12 56.5 ± 35.5 vs 145.0 ± 14.2 PRUs, p <0.05, respectively). In conclusion, anemia is an important contributor to apparent HRPR on clopidogrel and may explain some of the intraindividual variability of platelet aggregation testing.

Late bacterial endocarditis of an amplatzer atrial septal defect occluder device

A 66-year-old man with a large secundum atrial septal defect (ASD) that had been repaired percutaneously 30 months previously with an Amplatzer ASD occluder (ASO) presented with fevers and Staphylococcus aureus bacteremia. Transesophageal echocardiography revealed a 1.5 x 1.5 cm mobile mass on the left atrial side of his ASO consistent with a vegetation. When the ASO was explanted, the left atrial side of the device was poorly endothelialized. In conclusion, the present report is the first description of late infective endocarditis in an adult with an ASO.

Phasic coronary blood flow patterns in dogs vs. pigs: an acute ischemic heart study

BACKGROUND

Canine and porcine hearts have been widely used to investigate diagnoses, interventions, and surgical therapies for ischemic heart disease. Dogs and pigs are known to vary with regard to the anatomic distribution of their coronary arteries. However, the mechanisms of these differences and the differing phasic coronary blood flow patterns between the two species are not well characterized.

MATERIAL/METHODS

Phasic coronary blood flow patterns and hemodynamic data were analyzed using three flow probes placed around the left anterior descending (LAD), left circumflex (LCX), and right coronary (RCA) arteries in both canine and porcine models.

RESULTS

Systolic left ventricular pressure, arterial pressure, and systemic vascular resistance in dogs were higher than in pigs. Likewise, total coronary blood flow, LAD flow, and LCX flow were higher in dogs than in pigs. LCX flow was higher in dogs, but RCA flow was higher in pigs. Diastolic fraction and diastolic/systolic peak velocity ratio of the LAD, LCX, and RCA showed no significant differences at baseline between dogs and pigs. Systolic LAD flow in dogs decreased after the creation of an LAD stenosis, whereas systolic LAD flow in pigs increased.

CONCLUSIONS

Coronary blood flow patterns in dogs and pigs are quite different. These findings are potentially relevant to understanding the physiology of myocardial blood perfusion in dogs and pigs with ischemic heart disease.

Ventral cardiac denervation increased right coronary arterial blood flow

BACKGROUND

Cardiac denervation accompanied with coronary artery bypass surgery has been widely performed for the treatment of vasospastic angina associated with atherosclerotic coronary artery disease. However, the effect of cardiac denervation on phasic coronary blood flow patterns of the left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX) and right coronary artery (RCA) remains unknown. This study aimed to investigate the effect of cardiac denervation on phasic coronary blood flow patterns of the LAD, LCX and RCA.

METHODS

Phasic coronary blood flow patterns were analyzed using three flow probes placed around the LAD, LCX and RCA with and without LAD stenosis. Ventral cardiac denervation (VCD) was performed in 8 pigs, and 16 pigs were used as control subjects. Autonomic activities before and after the VCD were quantified by wavelet analysis of heart rate variability.

RESULTS

The mean LAD flow (34.4+/-9.4 to 32.6+/-7.1 ml/min, p=0.638) and mean LCX flow (26.3+/-10.2 to 27.2+/-6.0 ml/min, p=0.825) showed no significant change after VCD, while the mean RCA flow (31.3+/-9.0 to 38.2+/-11.2 ml/min, p=0.003) significantly increased. The hemodynamic variables in the VCD group were well maintained after creation of LAD stenosis, while they deteriorated in the control group. The low-frequency components, high-frequency components and their ratio did not change after VCD.

CONCLUSIONS

VCD prevented the deterioration of cardiac function after creation of an LAD stenosis and resulted in an increase of the mean RCA flow. VCD did not affect autonomic nervous system activity.

Impact of left atrial appendage exclusion on left atrial function

OBJECTIVES

We sought to investigate the short-term and midterm effects of left atrial appendage exclusion on left atrial function. Left atrial appendage exclusion is considered a possible therapeutic option for stroke prevention in patients with atrial fibrillation. Favorable outcomes have encouraged widespread use of left atrial appendage exclusion for cardiac surgical patients-even for patients in sinus rhythm who have stroke risk factors; however, the chronic effects on left atrial function of left atrial appendage exclusion are unclear.

METHODS

Nineteen mongrel dogs (29.7 +/- 5.2 kg) in sinus rhythm were studied. The Doppler signals from the pulmonary venous flow, transmitral flow, and tissue Doppler imaging of mitral annular motion were obtained before and after left atrial appendage exclusion. Dogs were evaluated in the same manner at 7 days (n = 2), 30 days (n = 7), or 90 days (n = 10) after left atrial appendage exclusion.

RESULTS

Except for a significant increase in early diastolic transmitral flow velocity after left atrial appendage exclusion (P = .01), no significant differences were found in any parameters related to the transmitral flow and tissue Doppler imaging measurements throughout follow-up. The systolic components of pulmonary venous flow at follow-up revealed a significant reduction relative to baseline (peak systolic velocity P < .0001, systolic velocity-time integral P < .0001), despite the lack of significant changes in left atrial pressure, left ventricular volume, and stroke volume.

CONCLUSION

Left atrial appendage exclusion may affect left atrial reservoir function in the short-term and midterm periods. Further long-term studies with more clinically relevant models are needed.

Development of a small implantable right ventricular assist device

The purpose of this program is to design, develop, and clinically evaluate a new, implantable right ventricular assist device (RVAD) that can be used as a component of an implantable biventricular assist device for patients with severe biventricular heart failure. The initial phase of this program resulted in a prototype RVAD, named DexAide, a modified version of the CorAide left ventricular assist device. In vitro testing was performed in a stand-alone circuit and in a true RVAD mode to evaluate pump performance. Pump flow and power were measured under various afterload and pump speed conditions. The pump performance requirements of 2 to 6 l/min and a pressure rise of 20 to 60 mm Hg were successfully met with pump speeds between 1,800 and 3,200 rpm. The nominal design point of 4 l/min and 40 mm Hg pressure rise was achieved at 2,450 +/- 70 rpm with a power consumption of 3.0 +/- 0.2 W. The initial in vitro testing met the design criteria for the new DexAide RVAD. Initial in vivo testing is under way, which will be followed by preclinical readiness testing and a pilot clinical trial in this 5-year program.

In vitro performance of the novel coronary sinus AutoRetroPerfusion Cannula

Myocardial salvage through coronary sinus intervention has been documented. The AutoRetroPerfusion Cannula is a novel device that is able to perfuse the coronary bed retrogradely through the coronary sinus with arterial blood generated from a peripheral artery with no need for a pump. The cannula consists of a distal end that, once secured in the coronary sinus, opens an umbrella-like membrane to create pressure in the coronary sinus, and at the same time has small channels directed backwards to the right atrium to provide pressure relief. The cannula is introduced from the axillary vein under local anesthesia and the proximal end, which consists of a graft, is anastomosed to the axillary artery to start autoperfusion once the distal end is secured in the coronary sinus and the occluding membrane is open. The AutoRetroPerfusion Cannula was tested in the in vitro mock loop under 50-120 mm Hg of proximal pressure and 50, 100, and 150 ml/min of total flow in the cannula. We were able to achieve the nominal design point of 40-80 mm Hg of distal pressure and 50-150 ml/min of distal flow by adjusting the number, diameter, and length of the small backwards channels.

A novel device for left atrial appendage exclusion

OBJECTIVE

The left atrial appendage is a frequent source of thromboemboli in patients with atrial fibrillation. Exclusion or excision of the left atrial appendage may reduce the risk of stroke in patients with atrial fibrillation. We evaluated the ability of a novel device to exclude the left atrial appendage during early and intermediate follow-up periods in a canine model.

METHODS

Eight mongrel dogs (mean weight 29.1 +/- 4.0 kg) were used in this study. The occlusion device, constructed from 2 stainless steel strips covered with a knit braided polyester fabric, was implanted at the base of the left atrial appendage through a left thoracotomy on a beating heart. Dogs were evaluated at 7 days (n = 2), 30 days (n = 2), and 90 days (n = 4) by epicardial echocardiography, left atrial angiography, histologic inspection, and gross pathology.

RESULTS

Device implantation was performed without complications in all animals. Complete exclusion of the left atrial appendage from the circulation was confirmed acutely and chronically by echocardiographic and angiographic evaluations. There was no device migration or damage to adjacent structures.

CONCLUSION

This novel device enables rapid, reliable, and safe exclusion of the left atrial appendage. The device provides a new therapeutic option for reducing the risk of stroke in patients with atrial fibrillation.

Phasic coronary blood flow pattern during a continuous flow left ventricular assist support

OBJECTIVE

Continuous flow left ventricular assist devices (LVADs) have been introduced and tested as a bridge to heart transplantation, bridge to recovery, and destination therapy, and several studies have been conducted to assess the physiologic effects of continuous flow LVADs. However, the effect of reduced pulsatility on the phasic coronary blood flow pattern is unknown. The aim of this study was to investigate the phasic coronary blood flow patterns during continuous flow LVAD support.

METHODS

Phasic coronary blood flow patterns and hemodynamic data were analyzed using three flow probes placed around the left anterior descending coronary artery (LAD), left circumflex coronary artery (LCX), and the right coronary artery (RCA) in 16 pigs before and after initiating the LVAD support with or without creating LAD stenosis.

RESULTS

The total coronary blood flow (TCBF, 112.8+/-31.4 mL/min) gradually decreased when the continuous flow LVAD support increased to 2.0 L/min (110.7+/-29.0 mL/min, P = 0.571), 2.5 L/min (103.7+/-26.1 mL/min, P = 0.079), and 3.0 L/min (101.5+/-27.2 mL/min, P = 0.027) because of decreases in LAD flow and LCX flow. LVAD support caused decrease in systolic and peak systolic LAD flow, LCX flow, and RCA flow, whereas diastolic RCA flow increased. In the presence of LAD stenosis, the TCBF (97.7+/-36.1 mL/min) decreased when the continuous flow LVAD support increased to 2.0 L/min (83.9+/-22.1 mL/min, P = 0.029), 2.5 L/min (83.2+/-25.2 mL/min, P = 0.012), and 3.0 L/min (87.6+/-23.4 mL/min, P = 0.005) because of decreases in LCX flow.

CONCLUSION

Use of a continuous flow LVAD decreased TCBF, LAD flow, and LCX flow secondary to reduced systolic LAD flow and LCX flow, and decreased TCBF and LCX flow in the presence of LAD stenosis. These findings are potentially relevant to understanding the physiology of myocardial blood perfusion during continuous flow LVAD support especially in patients with coronary artery disease.

Initial In Vivo Evaluation of the DexAide Right Ventricular Assist Device

Despite the increasing use of left ventricular assist devices for patients with end-stage congestive heart failure, no implantable, centrifugal right ventricular assist devices (RVADs) are available for those patients with significant right ventricular failure. The DexAide RVAD was developed to provide an implantable RVAD option to surgeons. The aim of this study was to evaluate pump performance in an acute in vivo model. The DexAide RVAD, developed as a modified CorAide left ventricular assist device, was implanted between the right ventricle and the pulmonary artery in four healthy calves. Pump speed was varied from 1800 rpm to 3600 rpm. RVAD performance was analyzed acutely at baseline and under conditions of low circulating volume, high contractility, high pulmonary arterial pressure, vasodilation, and low contractility. Pump flow was well maintained even under conditions of high pulmonary arterial pressure and vasodilation, with the exception of low circulating volume. Under all conditions, pulmonary arterial pressures were not affected by changing pump speed. The DexAide RVAD demonstrated acceptable hemodynamic characteristics for use as an implantable RVAD in the initial acute studies. Further studies are ongoing to examine the biocompatibility of the pump under chronic conditions.

Performance and Reliability of the CPB/ECMO Initiative Forward Lines Casualty Management System

The Cleveland Clinic Foundation CPB/ECMO Initiative Forward Casualty Management System is an economical, compact, transportable, disposable system designed to permit a rapid expansion of trauma management services requiring cardiopulmonary bypass (CPB) or extracorporeal membrane oxygenation (ECMO) pulmonary support. The system, composed of a rotary blood pump, a pump motor driver, and an electronic control console as the blood pumping subsystem, also includes commonly used compatible commercial oxygenators, venous reservoirs, and cannulae. In vitro durability testing accumulated over 100 hours without failure. In vivo reliability was tested in 10 calves under general anesthesia during 6 hours of CPB and ECMO under full heparinization at nominal operating conditions of 4-5 l/min and 2-4 l/min blood flow respectively, and mean arterial pressures between 65 and 100 mm Hg. A mean time to failure of 57 hours was reached during the animal series. Results of these test series demonstrated that this system has the capability to reliably operate during a 6-hour conventional CPB or ECMO procedure, while providing flexibility and ease of use for the operator.