Michael W.A. Chu

Transapical minimally invasive aortic valve implantation; the initial 50 patients §

OBJECTIVE To evaluate the feasibility of minimally invasive transapical beating heart aortic valve implantation (TAP-AVI) for high-risk patients with aortic stenosis. METHODS TAP-AVI was performed via a small anterolateral minithoracotomy in 50 patients from February 2006 to March 2007. A balloon expandable transcatheter xenograft (Edwards SAPIEN THV, Edwards Lifesciences, Irvine, CA, USA) was used. Mean age was 82.4+/-5 years and 39 (78%) were female. Implantation was performed in a hybrid operative theatre using fluoroscopic and echocardiographic visualization. Average EuroSCORE predicted risk for mortality was 27.6+/-12%. Seven (14%) patients were re-operations with patent bypass grafts. RESULTS TAP-AVI (13 patients 23 mm and 37 patients 26 mm) was successfully performed on the beating heart under temporary rapid ventricular pacing in 47 (94%) patients, and implantation was performed completely off-pump in 34 (68%) patients. Three patients required early conversion; two of them were successfully discharged. There was no prosthesis migration or embolization observed. Echocardiography revealed good hemodynamic function in all and minor incompetence in 23 patients, mostly paravalvular, without any signs of hemolysis. Mortality was due to the overall health condition and non-valve related in all patients. Actuarial survival at 1 month, 6 months and 1 year was 92+/-3.8%, 73.9+/-6.2% and 71.4+/-6.5%, respectively. CONCLUSIONS Transapical minimally invasive aortic valve implantation is feasible using an off-pump technique. Good results have been achieved in the initial 50 patients, especially when considering the overall high-risk profile of these patients.

Bicuspid aortic valve disease and ascending aortic aneurysms: gaps in knowledge.

The bicuspid aortic valve is the most common congenital cardiac anomaly in developed nations. The abnormal bicuspid morphology of the aortic valve results in valvular dysfunction and subsequent hemodynamic derangements. However, the clinical presentation of bicuspid aortic valve disease remains quite heterogeneous with patients presenting from infancy to late adulthood with variable degrees of valvular stenosis and insufficiency and associated abnormalities including aortic coarctation, hypoplastic left heart structures, and ascending aortic dilatation. Emerging evidence suggests that the heterogeneous presentation of bicuspid aortic valve phenotypes may be a more complex matter related to congenital, genetic, and/or connective tissue abnormalities. Optimal management of patients with BAV disease and associated ascending aortic aneurysms often requires a thoughtful approach, carefully assessing various risk factors of the aortic valve and the aorta and discerning individual indications for ongoing surveillance, medical management, and operative intervention. We review current concepts of anatomic classification, pathophysiology, natural history, and clinical management of bicuspid aortic valve disease with associated ascending aortic aneurysms.

US–Fluoroscopy Registration for Transcatheter Aortic Valve Implantation

Transcatheter aortic valve implantation is a minimally invasive alternative to open-heart surgery for aortic stenosis in which a stent-based bioprosthetic valve is delivered into the heart on a catheter. Limited visualization during this procedure can lead to severe complications. Improved visualization can be provided by live registration of transesophageal echo (TEE) and fluoroscopy images intraoperatively. Since the TEE probe is always visible in the fluoroscopy image, it is possible to track it using fiducial-based single-perspective pose estimation. In this study, inherent probe tracking performance was assessed, and TEE to fluoroscopy registration accuracy and robustness were evaluated. Results demonstrated probe tracking errors of below 0.6 mm and 0.2°, a 2-D RMS registration error of 1.5 mm, and a tracking failure rate of below 1%. In addition to providing live registration and better accuracy and robustness compared to existing TEE probe tracking methods, this system is designed to be suitable for clinical use. It is fully automatic, requires no additional operating room hardware, does not require intraoperative calibration, maintains existing procedure and imaging workflow without modification, and can be implemented in all cardiac centers at extremely low cost.

Single-stage hybrid coronary revascularization with long-term follow-up

OBJECTIVES Hybrid coronary revascularization, performing a left internal thoracic artery (LITA) to left anterior descending (LAD) bypass followed by percutaneous coronary intervention (PCI) in a non-LAD coronary artery lesion, represents an evolving revascularization strategy. It utilizes the survival benefit of the LITA-to-LAD bypass, while providing complete revascularization with PCI to a non-critical vessel to decrease procedural morbidity. However, quantitative patency results and clinical outcomes remain understudied. The objective of this study was to assess clinical follow-up and graft and stent patency at 6 months and 5 years in a single-stage hybrid revascularization population. METHODS From 2004 to 2012, a total of 96 patients (64 ± 12 years; 70 males and 26 females) consented to robotic-assisted LITA harvesting and a small left anterior thoracotomy for off-pump coronary artery bypass anastomosis onto the LAD. This was followed immediately by PCI in a non-LAD vessel in the same fluoroscopy-equipped hybrid operating room. Patients underwent a yearly clinical follow-up and a protocol-directed assessment of graft patency via a coronary angiogram at 6 months and cardiac computed tomography (CT) angiography with single-photon emission computed tomography myocardial perfusion scintigraphy (MPS) at 5 years. RESULTS Successful single-stage hybrid revascularization occurred in 94 of the 96 patients (2 patients required intraoperative conversion to conventional coronary bypass). Six-month protocol coronary angiogram follow-up has been performed in 85 patients. Fitzgibbon Grade A or B LITA-to-LAD patency at 6-month follow-up was 94% in those studied. A total of 105 stents were deployed (89 drug-eluting stents (DES) and 16 bare metal), and at 6-month follow-up in 85 patients, 79 stents were widely patent; 8 had in-stent restenosis, and 2 were completely occluded. To date, 19 patients have undergone 5-year coronary CT angiography and MPS. The LITA-to-LAD anastomosis was patent in 17 of the 19 patients. Of the 19 lesions in which PCI was performed, 17 were widely patent, while 2 circumflex DES were occluded. Five-year clinical outcome demonstrated 91% survival, 94% freedom from angina and 87% freedom from any form of coronary revascularization. CONCLUSIONS A single-stage hybrid revascularization strategy appears to have acceptable 6-month and angiographic patency results for both LITA-LAD grafts and PCI interventions. Survival, freedom from angina and freedom from revascularization also appear favourable at the 5-year clinical follow-up.

Does the Trainee's Level of Experience Impact on Patient Safety and Clinical Outcomes in Coronary Artery Bypass Surgery?

Abstract  Background: There is a relative dearth of information on how the residents level of training affects patient outcomes in cardiac surgery. We designed this study to determine if there were any significant differences in patient demographics and clinical outcomes of coronary artery bypass procedures (CABG) performed by residents of PGY 4/lower, residents of PGY 5/6, fellows, or consultants. Methods: Standardized preoperative, intraoperative, and postoperative variables were prospectively collected and analyzed on 2906 isolated CABG procedures, performed between July 1999 and March 2006 with the primary surgeon prospectively classified as PGY4/lower, PGY5/6, fellow, and consultant. Results: The number of cases performed by residents of PGY4/lower, PGY5/6, fellows and consultants were 179, 263, 301, and 2163, respectively. Preoperative demographics and comorbidities were similar except PGY4/lower group had more diabetics and consultant group had more patients requiring IABP. More non‐LIMA arterial conduits were used in the consultant and fellow groups. However, there were neither significant differences in the mean number of grafts nor in the composite postoperative morbidity, median ICU, and hospital lengths of stay. Observed in‐hospital mortality was 2.2%, 1.5%, 1.7%, and 2.7% (p = 0.49), respectively. Conclusions: Preoperative patient demographics and operative data were similar in all groups except that patients requiring IABP preoperatively were more likely operated on by consultants and arterial revascularization was performed more commonly by consultants and fellows. Postoperative mortality and morbidity rates were similar among all groups, thus demonstrating that with appropriate supervision, trainees of all levels can safely be taught CABG.

Collagenase-resistant collagen promotes mouse aging and vascular cell senescence

Collagen fibrils become resistant to cleavage over time. We hypothesized that resistance to type I collagen proteolysis not only marks biological aging but also drives it. To test this, we followed mice with a targeted mutation (Col1a1r/r) that yields collagenase‐resistant type I collagen. Compared with wild‐type littermates, Col1a1r/r mice had a shortened lifespan and developed features of premature aging including kyphosis, weight loss, decreased bone mineral density, and hypertension. We also found that vascular smooth muscle cells (SMCs) in the aortic wall of Col1a1r/r mice were susceptible to stress‐induced senescence, displaying senescence‐associated ß‐galactosidase (SA‐ßGal) activity and upregulated p16INK4A in response to angiotensin II infusion. To elucidate the basis of this pro‐aging effect, vascular SMCs from twelve patients undergoing coronary artery bypass surgery were cultured on collagen derived from Col1a1r/r or wild‐type mice. This revealed that mutant collagen directly reduced replicative lifespan and increased stress‐induced SA‐ßGal activity, p16INK4A expression, and p21CIP1 expression. The pro‐senescence effect of mutant collagen was blocked by vitronectin, a ligand for αvß3 integrin that is presented by denatured but not native collagen. Moreover, inhibition of αvß3 with echistatin or with αvß3‐blocking antibody increased senescence of SMCs on wild‐type collagen. These findings reveal a novel aging cascade whereby resistance to collagen cleavage accelerates cellular aging. This interplay between extracellular and cellular compartments could hasten mammalian aging and the progression of aging‐related diseases.

Unilateral Postoperative Pulmonary Edema After Minimally Invasive Cardiac Surgical Procedures: A Case-Control Study

BACKGROUND Unilateral postoperative pulmonary edema is an underreported adverse event after a minimally invasive cardiac surgical procedure that combines right minithoracotomy with cardiopulmonary bypass. We sought to characterize its incidence, risk factors, and morbidity. METHODS We conducted a retrospective case-control study of all cardiac surgical procedures that combined right-sided minithoracotomy with cardiopulmonary bypass at our institution over 8 consecutive years. Unilateral postoperative pulmonary edema was defined on the chest radiograph taken on the first postoperative day as relatively increased opacification of the right versus left hemithorax involving at least 20% of the hemithorax, not better explained by atelectasis. Baseline characteristics, potential risk factors, and outcomes were subject to univariable and multivariable analysis. RESULTS Radiographs were available for 277 of 278 patients; of those, 68 (25%) met our definition of unilateral postoperative pulmonary edema. Patients with unilateral postoperative pulmonary edema had higher mortality and were more likely to have a lower postoperative PaO2/FIO2 ratio, to require vasoactive medications and mechanical ventilation for longer than 24 hours, and to have longer lengths of stay in the intensive care unit and the hospital. Unilateral postoperative pulmonary edema was independently associated with chronic obstructive pulmonary disease (odds ratio [OR] 4.79; 95% confidence interval [CI] 1.28 to 18.0; p = 0.02); pulmonary hypertension, right-ventricular dysfunction, or both (OR 2.92; 95% CI 1.41 to 6.03; p = 0.004); and increasing cardiopulmonary bypass time (OR 1.019; 95% CI 1.011 to 1.027 per additional minute; p <0.001). CONCLUSIONS Unilateral postoperative pulmonary edema after minimally invasive cardiac surgical procedures is common, carries significant morbidity, and has identifiable risk factors. Further research is needed to enable a better understanding of the pathophysiology and clinical implications of unilateral postoperative pulmonary edema.

State-of-the-Art Surgical Management of Acute Type A Aortic Dissection

Acute type A aortic dissections still present a major challenge to cardiac surgeons. Although surgical management remains the gold standard, operative mortality remains high, including in experienced centres. Nevertheless, recent advances in the understanding and management of various aspects of these complex operations are expected to improve overall patient outcomes. The Canadian Thoracic Aortic Collaborative (CTAC) represents a group of surgeons with interest and expertise in the management of patients with aortic diseases. The purpose of this state-of-the-art review is to detail our approach to the contemporary surgical management of acute type A aortic dissections. We focus specifically on cannulation strategies, cerebral protection, and extent of proximal and distal resection. In addition, specific clinical scenarios-including malperfusion, intramural hematomas, and surgery in octogenarians-are explored.

Canadian Cardiovascular Society/Canadian Society of Cardiac Surgeons/Canadian Society for Vascular Surgery Joint Position Statement on Open and Endovascular Surgery for Thoracic Aortic Disease

In 2014, the Canadian Cardiovascular Society (CCS) published a position statement on the management of thoracic aortic disease addressing size thresholds for surgery, imaging modalities, medical therapy, and genetics. It did not address issues related to surgical intervention. This joint Position Statement on behalf of the CCS, Canadian Society of Cardiac Surgeons, and the Canadian Society for Vascular Surgery provides recommendations about thoracic aortic disease interventions, including: aortic valve repair, perfusion strategies for arch repair, extended arch hybrid reconstruction for acute type A dissection, endovascular management of arch and descending aortic aneurysms, and type B dissection. The position statement is constructed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and has been approved by the primary panel, an international secondary panel, and the CCS Guidelines Committee. Advent of endovascular technology has improved aortic surgery safety and extended the indications of minimally invasive thoracic aortic surgery. The combination of safer open surgery with endovascular treatment has improved patient outcomes in this rapidly evolving subspecialty field of cardiovascular surgery.

Transcatheter Aortic Valve Implantation With or Without Preimplantation Balloon Aortic Valvuloplasty: A Systematic Review and Meta‐Analysis

Background Preimplantation balloon aortic valvuloplasty (BAV) is considered a routine procedure during transcatheter aortic valve implantation (TAVI) to facilitate prosthesis implantation and expansion; however, it has been speculated that fewer embolic events and/or less hemodynamic instability may occur if TAVI is performed without preimplantation BAV. The aim of this study was to systematically review the clinical outcomes associated with TAVI undertaken without preimplantation BAV. Methods and Results We conducted a search of Medline and Embase to identify studies that evaluated patients who underwent TAVI with or without preimplantation BAV for predilation. Pooled analysis and random‐effects meta‐analyses were used to estimate the rate and risk of adverse outcomes. Sixteen studies involving 1395 patients (674 with and 721 without preimplantation BAV) fulfilled the inclusion criteria. Crude device success was achieved in 94% (1311 of 1395), and 30‐day all‐cause mortality occurred in 6% (72 of 1282) of patients. Meta‐analyses evaluating outcomes of strategies with and without preimplantation BAV showed no statistically significant differences in terms of mortality (relative risk [RR] 0.61, 95% CI 0.32–1.14, P=0.12), safety composite end point (RR 0.85, 95% CI 0.62–1.18, P=0.34), moderate to severe paravalvular leaks (RR 0.68, 95% CI 0.23–1.99, P=0.48), need for postdilation (RR 0.86, 95% CI 0.66–1.13, P=0.58), stroke and/or transient ischemic attack (RR 0.72, 95% CI 0.30–1.71, P=0.45), and permanent pacemaker implantation (RR 0.80, 95% CI 0.49–1.30, P=0.37). Conclusions Our analysis suggests that TAVI procedures with or without preimplantation BAV were associated with similar outcomes for a number of clinically relevant end points. Further studies including a large number of patients are needed to ascertain the impact of TAVI without preimplantation BAV as a standard practice.