Surgical Valve Choices for Pulmonary Valve Replacement.

The range of valve choices available to the cardiac surgeon for placement in the pulmonary position continues to expand. This article will provide a brief compendium of the most clinically relevant among these choices and review the contemporary literature regarding their relative durability as well as risk factors for structural valve deterioration and reintervention. The unique advantages and disadvantages of each of these valve choices will be discussed as they pertain to unique patient-specific factors, including patient size and the anatomy of the right ventricular outflow tract, that inform the choice of one prosthesis over another. Finally, general principles regarding the approach to valve choice, and future directions will be discussed.

Complete atrioventricular septal defect with absent or diminutive primum component: Incidence, anatomic characteristics, and outcomes.

BACKGROUND: Repair of complete atrioventricular septal defect with absent or diminutive primum defect is challenging because of atrial septal malposition and abnormal anatomy of the left atrioventricular valve. We sought to define the incidence, anatomy, and surgical outcomes of this entity. METHODS: We identified all patients in our institutional database presenting for complete atrioventricular septal defect repair from 2006 to 2018. Operative reports and echocardiograms were reviewed to determine the presence and size of the primum defect, atrioventricular valve anatomy, degree of atrioventricular valve regurgitation, repair method, and complications, including reoperation for atrioventricular valve regurgitation. Functionally univentricular patients and those receiving repair at an outside institution were excluded. RESULTS: Of 183 patients with complete atrioventricular septal defect, absent/diminutive primum defect occurred in 16 patients (8.7%; 10 absent, 6 diminutive). Six patients (38%) had leftward malposition of the atrium septum on the common atrioventricular valve. The rate of reoperation for left atrioventricular valve regurgitation was 31% (3 early, 2 late), for which preoperative predictors included leftward malposition of the atrial septum onto the common atrioventricular valve (4/6 patients with malposition required reoperation, P = .036, Fisher exact test). One patient exhibiting this risk factor died. The overall rate of moderate or greater left atrioventricular valve regurgitation on the most recent postoperative echocardiogram was 13% (2/16 patients; median follow-up, 141 days; range, 3-2236 days). CONCLUSIONS: Complete atrioventricular septal defect with absent or diminutive primum defect is a unique variant of complete atrioventricular septal defect for which the risk of reoperation for left atrioventricular valve regurgitation after complete repair is high and risk factors include leftward malposition of the atrial septum on the common atrioventricular valve.

Neonatal venoarterial extracorporeal membrane oxygenation cannulation technique.

Peripheral cannulation for initiation of neonatal venoarterial extracorporeal membrane oxygenation is an essential technical skill in the armamentarium of every congenital cardiac surgeon and is necessary for the care of newborns with congenital heart disease and other conditions presenting with cardiopulmonary failure. With certain exceptions, it is usually performed via a right neck cut-down to expose the right internal jugular vein and common carotid artery.   A strong understanding of the fundamental techniques, as well as strategies for avoiding common pitfalls, is critical to the success of cardiopulmonary rescue afforded by cannulation, especially considering the emergent conditions under which cannulation must usually be performed. We review here the operative approach and technique for neck cannulation for peripheral neonatal venoarterial extracorporeal membrane oxygenation.

Ascending Aortoplasty in Pediatric Patients Undergoing Aortic Valve Procedures.

BACKGROUND: The risks of ascending aortic dilation and indications for intervention in pediatric patients are unclear. Given the concern for aortic size mismatch with growth, larger ascending aortic diameters have been accepted in pediatric patients. The purpose of this study was to evaluate the effectiveness of ascending aortic reduction at the time of aortic valve surgery and its effect on recurrent aortic regurgitation. METHODS: A retrospective 8-year observational review (2010-2018) was conducted in pediatric patients with dilated ascending aorta undergoing aortic valve surgery at a single institution. RESULTS: Forty-seven patients underwent ascending aortoplasty during aortic valve surgery, of which 39 patients with complete data points had preoperative mean ascending aortic Z-scores of 5.35 ± 1.52 reduced to 1.22 ± 1.63 (P < .001) postoperatively. Ascending aortic Z-scores remained similar at 1.37 ± 1.72 at latest follow-up (P = .306). In contrast our matched control group (n = 39) without ascending aortoplasty had preoperative mean ascending aortic Z-scores of 4.15 ± 1.65 reduced to 3.26 ± 2.0 at the midterm follow-up. This reduction was significantly larger in the aortoplasty group, with an average difference in these changes of 3.12 (95% confidence interval, 2.43-3.8; P < .001). Multivariable logistic regression (controlling for aortic valve intervention type and body surface area) showed a 6.84 odds of moderate to severe aortic regurgitation at follow-up in the control group compared with the aortoplasty group (95% confidence interval, 1.43-32.8; P = .016). There were no complications associated with ascending aortoplasty. CONCLUSIONS: Ascending aortoplasty is effective in reducing ascending aortic dimensions and recurrent aortic regurgitation in pediatric patients. Longer-term follow-up is necessary to determine continued rate of growth.

Pulmonary Valve-Sparing Techniques for Tetralogy of Fallot: A Systematic Approach for Maximizing Success and Minimizing Risk.

Valve-sparing techniques for the treatment of Tetralogy of Fallot with pulmonary stenosis have evolved over the past few decades. This article will discuss the rationale for a more aggressive approach to sparing the pulmonary valve, the various techniques available (including commissurotomy, leaflet thinning and debridement, balloon dilation, and finally modified monocusp repair), as well as a systematic approach for employing these techniques based on individual patient anatomy in a manner that takes full advantages of the benefits of the valve-sparing approach while mitigating the risks involved.

Early Distal Migration of a Self-Expanding Aortic Valve Prosthesis Causing Myocardial Infarction.

Early distal migration after transcatheter aortic valve replacement is a rare but potentially catastrophic complication that presents unique technical challenges for subsequent surgical management. This report describes a case of early distal migration of a Medtronic CoreValve Evolut R bioprosthesis (Minneapolis, MN) causing myocardial infarction from coronary ostial obstruction and provides a practical technique for open surgical device explantation and aortic valve re-replacement. Snaring the stent of the device using standard instruments is a simple but effective method for transcatheter aortic valve replacement explant that allows for optimal positioning of a single aortotomy at the standard anatomic site to facilitate subsequent surgical aortic valve replacement.

Bicuspid Aortic Valvulopathy and Associated Aortopathy: a Review of Contemporary Studies Relevant to Clinical Decision-Making.

OPINION STATEMENT: The bicuspid aortic valve (BAV) phenotype is becoming increasingly recognized as a complex and heterogeneous clinical entity, with some but not all patients developing accelerated degrees of both aortic insufficiency (AI) and aortic stenosis (AS) in comparison to patients with tricuspid aortic valves (TAV). In addition, there remains a well-established association between the BAV phenotype and aortic enlargement independent of valve function as well as progression among some to ascending aortic aneurysm and the attendant concern over risk of aortic dissection. Because the understanding of the complexity of the BAV phenotype is evolving as quickly as are the options for medical, surgical, and interventional therapy, this review aims to provide an update on the most clinically relevant recent advances in the realm of BAV and associated aortopathy from a genetic, morphologic, and clinical outcomes perspective in order to give the practicing clinician a deeper understanding of how to approach both medical and surgical decision-making in the patient with BAV. The following major principles have emerged in recent years including (1) the importance of cusp anatomy and its implications on the long-term risk of AI, aortic dilation, and aortic dissection, (2) the role of post-valvular flow dynamics in the pathogenesis of aortic dilation in BAV patients, (3) the ability of aortic valve replacement to halt accelerated dilation rates, and (4) the finding that the risk of aortic dissection, while still overall intermediate is much more akin to the baseline risk present in TAV patients rather than the much higher rates observed in patients with Marfan's disease. Together, these data support the less aggressive approach to aortic replacement in BAV patients as reflected in the most recent ACC/AHA guidelines and provide a stronger basis upon which future studies, including those aimed at medical and transcatheter therapies, stand to make further impact on our ability to optimally treat this epidemiologically important and complex population of patients.

Recurrence of mitral regurgitation after partial versus complete mitral valve ring annuloplasty for functional mitral regurgitation.

OBJECTIVES: Both partial and complete annuloplasty rings are used for mitral valve repair for patients with functional mitral regurgitation (FMR). We sought to determine if recurrence of mitral regurgitation (MR) is affected by the type of ring used. METHODS: Five hundred forty-eight patients diagnosed with FMR underwent mitral valve repair with ring annuloplasty between 1998 and 2008 in our institution. Medical records were reviewed retrospectively for clinical and echocardiographic data to determine the presence of recurrent MR (defined as moderate or severe). RESULTS: Among 479 patients for whom postoperative echocardiographic data were available, recurrent MR occurred less frequently in the complete versus partial ring group (20 of 209 [10%] vs 56 of 270 [21%] patients; P = .001), despite lower preoperative ejection fractions in the complete ring group (median, 35%; interquartile range, 25%-45% vs median, 40%; interquartile range, 30%-55%; P < .001). Kaplan-Meier analysis demonstrated greater freedom from recurrent MR in the complete ring group (108 vs 103 months; P = .001). Risk-matched propensity analysis of 102 patients per group (area under the curve, 0.824; 95% confidence interval, 0.788-0.861; P < .001) also demonstrated that complete ring recipients had greater freedom from recurrent MR than partial ring recipients by univariate analysis (7 [7%] vs 17 [17%] patients; P = .049), and a trend toward greater freedom by Kaplan-Meier analysis (110 vs 104 months; P = .068). CONCLUSIONS: The use of complete mitral annuloplasty rings provides improved freedom from recurrent MR in patients with FMR.

Ventricular restraint therapy for heart failure: A review, summary of state of the art, and future directions.

Congestive heart failure is a leading cause of death in developed countries, and its incidence is expected to increase in parallel with the aging population. Most current therapies for congestive heart failure lead to modest symptom relief but are unable to significantly improve long-term survival outcomes. Indeed, there is no effective treatment except cardiac transplantation, which remains epidemiologically insignificant because of donor pool limitations. New strategies for treating congestive heart failure are needed. Ventricular restraint is a promising, nontransplant surgical therapy in which the overall goal is to wrap the dilated, failing heart with prosthetic material to mechanically constrain the heart at end-diastole, prevent further remodeling, and thereby ultimately improve ventricular function, patient symptoms, and survival. In this review, the principles of cardiac restraint therapy will be discussed. An overview of 3 restraint devices, along with their specific advantages and disadvantages, will be presented. The existing peer-reviewed literature from both animal and human trials will be summarized with an emphasis on understanding the mechanism of restraint therapy and how this knowledge can be used to optimize and improve its efficacy.

Postoperative recurrence of mitral regurgitation after annuloplasty for functional mitral regurgitation.

BACKGROUND: We investigated predictive factors of postoperative recurrence of mitral regurgitation (MR) after mitral valve annuloplasty for functional ischemic MR. METHODS: This study was a retrospective review of patients with functional MR who underwent mitral ring annuloplasty at our institution from 1998 to 2008. Records were reviewed for perioperative variables, including echocardiographic measurements. Recurrence was defined as MR grade moderate (3+) or greater on any postoperative echocardiogram. RESULTS: Of 548 patients who underwent mitral annuloplasty for functional MR, echocardiogram reports were available for review for 250. These patients comprised the study cohort. There were 154 patients with concomitant coronary artery bypass grafting. The left ventricular (LV) end-diastolic (LVED) index was calculated by dividing the LVED dimension by body surface area (BSA). A high LVED index (>3.5 cm/m2) was predictive of MR recurrence (p=0.047): the recurrence rate was 20.3% (13 of 64) in high-index patients and 10.2% (19 of 186) in low-index (<3.5 cm/m2) patients. Median recurrence-free survival was 35 months (range, 19 to 59 months) in high-LVED-index patients and 46.5 months (range, 22 to 75 months) in low-LVED-index patients (p=0.048). Preoperative MR severity and LV ejection fraction were not predictive of MR recurrence. CONCLUSIONS: Careful analysis of the preoperative echocardiogram using a novel, easily calculated variable, the LVED index, may help identify patients who are at greater risk for MR recurrence and reduced survival. Such information could prompt consideration of alternative or additional interventions in these patients.

Warm ischemia provokes inflammation and regional hypercoagulability within the heart during off-pump coronary artery bypass: a possible target for serine protease inhibition.

OBJECTIVE: Accumulating evidence suggests that a hypercoagulable state influences early graft failure after off-pump coronary artery bypass (OPCAB). We hypothesized that regional myocardial ischemia caused by obligatory periods of coronary occlusion during OPCAB is an important trigger for this prothrombotic state. METHODS: Using a series of biomarkers, 60 consecutive patients undergoing OPCAB were monitored for myocardial injury (myoglobin), inflammation (TNF-alpha, IL-8) and thrombosis (thrombin generation-F1.2, contact activation pathway-FXII-a, platelet derived microparticles-via flow cytometry). The transcardiac gradients of these markers were determined by assaying both arterial and coronary sinus blood just after protamine administration. Intramyocardial pH was monitored continuously during coronary occlusion in a subset (N=30 grafts, 11 patients). The influence of management strategies affecting hemostasis (e.g. antiplatelet therapy, anti-fibrinolytics, peak activated clotting time (ACT) during heparinization) was analyzed. RESULTS: Ischemic injury, depicted by the transcardiac myoglobin gradient, significantly correlated with intramyocardial acidosis during coronary occlusion (R=0.96, p<0.0001) and predicted the transcardiac gradients of TNF-alpha (R=0.83, p<0.001) and F1.2 (R=0.72, p<0.0001). Transcardiac F1.2 strongly correlated with TNF-alpha (R=0.73, p=0.01) and IL-8 (R=0.51, p=0.02). Patients receiving aprotinin (N=20) showed significantly lower transcardiac gradients for myoglobin (4.1+/-7.5% vs 72.9+/-108.8% change, p=0.002), F1.2 (31+/-37% vs 89+/-149%, p=0.03), FXII-a (2.6+/-4.1% vs 19.2+/-34%, p=0.04) and microparticles (7+/-3.9% vs 12.9+/-8%, p=0.01). CONCLUSIONS: Strong correlations between myocardial ischemia and the transcardiac gradients of markers for inflammation and thrombosis suggest that even brief episodes of coronary occlusion in the beating heart may have pathophysiologic consequences. Aprotinin, but not other factors that influence the coagulation system, appears to mitigate this process during OPCAB.

The role of preexisting pathology in the development of neointimal hyperplasia in coronary artery bypass grafts.

OBJECTIVE: Saphenous vein grafts (SVG) used for coronary artery bypass surgery (CABG) often develop a gradual luminal narrowing over the first year due to neointimal hyperplasia (NH). Although the basic science of NH is well studied, our clinical understanding of this issue is limited. The purpose of this cohort study was to investigate clinical risk factors for NH by monitoring luminal narrowing within SVG using multichannel CT angiography (CTA). METHODS: Thirty patients underwent CABG involving SVG (N = 44) and arterial grafts (N = 36). Patient variables were recorded and the baseline quality of each conduit determined intraoperatively by analyzing surplus segments for intima-media thickness ratio (IMT) by histology and matrix metalloproteinase-2 by enzyme-linked immunosorbent assay. Percent luminal narrowing (%LN) was calculated for each patent graft by comparing the CTA appearance on day 5 to a repeat study at 1 y. RESULTS: Compared with arterial grafts, SVG showed significantly higher IMT at baseline (0.9 +/- 0.65 versus 0.22 +/- 0.17, P < 0.0001) and more %LN over the first year (6.9 +/- 7.5 versus 25.3 +/- 13.3% LN, P< 0.0001). Of all of the measured variables, the only significant predictors of %LN included baseline IMT (r = 0.58, P = 0.002) and matrix metalloproteinase-2 levels (r = 0.60, P = 0.002) in SVG. CONCLUSIONS: The degree of NH at baseline, a phenomenon exclusive to SVG and not found in arterial grafts, was significantly related to the development of lumen loss in the conduit over the first year after CABG. The study of SVG using serial CTA may provide unique insights into the natural history of SVG remodeling and to identify factors that influence the long-term function of this conduit.

Catheter-based infrared light scanner as a tool to assess conduit quality in coronary artery bypass surgery.

OBJECTIVES: Endothelial disruption within saphenous vein and radial artery grafts increases thrombosis risk. However, no clinically applicable method for imaging the intima currently exists. We used a novel infrared imaging technology, optical coherence tomography (OCT; LightLab Imaging, Inc, Westford, Mass), to visualize the intima within harvested conduits. METHODS: Conduits were procured endoscopically (37 saphenous vein grafts and 8 radial artery grafts) or with the open technique (9 radial artery grafts) from 50 patients. Surplus segments were analyzed by means of OCT for evidence of preexisting pathology or traumatic injury. Focal plaques in radial artery grafts and the intimal hyperplasia area in saphenous vein grafts were quantified as having an intimal/medial thickness ratio of greater than 0.5. Biopsy specimens were obtained for histologic confirmation and to analyze matrix metalloproteinase 2 levels (saphenous vein grafts) and prostacyclin/nitric oxide metabolites (radial artery grafts). Interobserver kappa coefficients and a Bland-Altman analysis were used to determine the reproducibility and accuracy of OCT interpretations. RESULTS: Radial artery imaging revealed plaque in 76%. Endoscopically harvested vessels showed intraluminal clot (38%) and intimal tears ranging from severe (6%) to mild (88%). In saphenous vein grafts intimal thickening was detected in 86% and intraluminal clotting in 68%. The intimal/medial thickness ratio determined by means of OCT correlated directly with matrix metalloproteinase 2 levels (R = 0.6804) in saphenous vein grafts and inversely with metabolites of prostacyclin (R = -0.55) and nitric oxide (R = -0.58) in radial artery grafts. OCT imaging was reproducible (interobserver kappa coefficients of >0.81 for the characterization of plaque types) and showed a strong correlation with histology (R = 0.8, P < .001). CONCLUSIONS: OCT imaging provides an accurate, real-time, and reproducible means for assessing saphenous vein graft and radial artery graft bypass conduits. As a quality assurance tool, this technology might afford a more objective basis for conduit selection.

Heart preservation using continuous ex vivo perfusion improves viability and functional recovery.

BACKGROUND: Cold static storage (CS) is a proven preservation method for heart transplantion, yet early postoperative graft dysfunction remains prevalent, so continuous perfusion (CP) during ex vivo transport may improve viability and function of heart grafts. METHODS AND RESULTS: Canine hearts underwent CP (n=9) or CS (n=9) for 6 h while intramyocardial pH was continuously monitored. Biopsies were assayed for ATP, caspase-3, malondialdehyde (MDA), and endothelin-1 (ET-1) levels at baseline, after preservation (t1), and after 1 h of blood reperfusion on a Langendorff model (t2). Functional recovery was determined at t2 by +dP/dt, -dP/dt, developed pressure, peak pressure and end-diastolic pressure. CP resulted in higher tissue pH and ATP stores and reduced caspase-3, MDA and ET-1 levels compared with CS at both t1 and t2. Post reperfusion recovery was significantly greater in CP vs CS for all myocardial functional parameters except end-diastolic pressure. Weight gain was significantly increased in CP vs CS at t1, but not at t2. CONCLUSIONS: Low-grade tissue acidosis and energy depletion occur during CS and are associated with oxidative injury and apoptosis during reperfusion. CP attenuates these biochemical and pathologic manifestations of tissue injury, together with improved myocardial recovery, despite mild, transient edema.

Off-Pump Coronary Artery Bypass Leads to a Regional Hypercoagulable State Not Detectable Using Systemic Markers.

OBJECTIVE: It is believed that off-pump coronary artery bypass grafting (OPCAB) leads to hypercoagulability, but efforts to document such a state have been unrevealing. We hypothesized that OPCAB increases the risk of developing a regional hypercoagulable state. METHODS: Blood was obtained from the aorta and coronary sinus (CS) after CABG performed off- (N=69) or on-pump (N=35) to determine the transcardiac gradients of F1.2 (thrombin production), XIIa (coagulation activation), myoglobin (ischemia) and IL-6, IL-8 using ELISA and platelet-derived microparticles using FACS. Platelet function was measured using aggregometry. Regional myocardial pH and SVG flow were recorded intraoperatively. SVG biopsies were analyzed for endothelial integrity (EI) using immunohistochemistry and graft patency was determined by predischarge CT angiography. RESULTS: Compared with on-pump, OPCAB provoked significantly higher transcardiac F1.2 (117±200 v. 31±38%), FXII-a (14±29 v. 2±4%), microparticles (14±-9.5% v. 6.4±-4.1%), IL-6 (119±183 v. 28±39%), and a trend toward increased IL-8 (67±94 v. 24±46%, P = 0.077). Myoglobin release after OPCAB, also greater than on-pump CABG (54±89 v. 8±14%, P < 0.01), correlated with regional pH change (R=-0.96, P < 0.0001), and F1.2 release (R=0.55, P = 0.0002). In contrast, systemic changes in these markers were all less after OPCAB. SVG flow was significantly reduced in OPCAB (39.4 versus 66.5 mL/min, P = 0.0002), but EI and graft patency rates were the same. CONCLUSIONS: Through the use of transcardiac assays, we illustrated that regional coagulation was enhanced after off- compared with on-pump CABG. If the findings of this pilot study are confirmed, OPCAB may require additional antithrombotic therapies to respond to this local hypercoagulable state.

Role of procurement-related injury in early saphenous vein graft failure after coronary artery bypass surgery.

Saphenous vein graft thrombosis after coronary artery bypass graft surgery is a poorly understood problem that lessens the benefits of this procedure. Recent studies highlight the importance of injury sustained at the time of saphenous vein graft procurement in the pathogenesis of acute graft thrombosis. In particular, damage to the graft endothelium that occurs secondary to ex vivo pressure distention, a common practice during vein harvest, leads to a loss of antithrombotic factors and increased activity of subendothelial prothrombotic factors. The prothrombotic potential of damaged grafts is further exacerbated by an ischemic storage interval and subsequent exposure to arterial flow conditions after grafting. A clearer understanding of the mechanisms by which endothelial disruption leads to acute saphenous vein graft thrombosis may result in interventions for improving our procurement techniques, interrupting the downstream effects of the damaged saphenous vein graft and/or discriminating damage that is beyond an acceptable threshold of thrombotic risk.