Joseph D. Schmoker

Long-Term Outcomes of Endoscopic Vein Harvesting After Coronary Artery Bypass Grafting

Background— Use of endoscopic saphenous vein harvesting has developed into a routine surgical approach at many cardiothoracic surgical centers. The association between this technique and long-term morbidity and mortality has recently been called into question. The present report describes the use of open versus endoscopic vein harvesting and risk of mortality and repeat revascularization in northern New England during a time period (2001 to 2004) in which both techniques were being performed. Methods and Results— From 2001 to 2004, 8542 patients underwent isolated coronary artery bypass grafting procedures, 52.5% with endoscopic vein harvesting. Surgical discretion dictated the vein harvest approach. The main outcomes were death and repeat revascularization (percutaneous coronary intervention or coronary artery bypass grafting) within 4 years of the index admission. The use of endoscopic vein harvesting increased from 34% in 2001 to 75% in 2004. In general, patients undergoing endoscopic vein harvesting had greater disease burden. Endoscopic vein harvesting was associated with an increased adjusted risk of bleeding requiring a return to the operating room (2.4 versus 1.7; P=0.03) but a decreased risk of leg wound infections (0.2 versus 1.1; P<0.001). Use of endoscopic vein harvesting was associated with a significant reduction in long-term mortality (adjusted hazard ratio, 0.74; 95% confidence interval, 0.60 to 0.92) but a nonsignificant increased risk of repeat revascularization (adjusted hazard ratio, 1.29; 95% confidence interval, 0.96 to 1.74). Similar results were obtained in propensity-stratified analysis. Conclusions— During 2001 to 2004 in northern New England, the use of endoscopic vein harvesting was not associated with harm. There was a nonsignificant increase in repeat revascularization, and survival was not decreased.

Effect of Preoperative Pulmonary Hypertension on Outcomes in Patients With Severe Aortic Stenosis Following Surgical Aortic Valve Replacement

Pulmonary hypertension (PH) is prevalent in patients with aortic stenosis (AS); however, previous studies have demonstrated inconsistent results regarding the association of PH with adverse outcomes after aortic valve replacement (AVR). The goal of this study was to evaluate the effects of preoperative PH on outcomes after AVR. We performed a regional prospective cohort study using the Northern New England Cardiovascular Disease Study Group database to identify 1,116 consecutive patients from 2005 to 2010 who underwent AVR ± coronary artery bypass grafting for severe AS with a preoperative assessment of pulmonary pressures by right-sided cardiac catheterization. PH was defined as a mean pulmonary artery pressure of ≥25 mm Hg, with severity based on the pulmonary artery systolic pressure-mild, 35 to 44 mm Hg; moderate, 45 to 59 mm Hg; and severe, ≥60 mm Hg. We found that PH was present in 536 patients (48%). Postoperative acute kidney injury, low-output heart failure, and in-hospital mortality increased with worsening severity of PH. In multivariate logistic regression, severe PH was independently associated with postoperative acute kidney injury (adjusted odds ratio 4.1, 95% confidence interval [CI] 1.7 to 10, p = 0.002) and in-hospital mortality (adjusted odds ratio 6.9, 95% CI 2.5 to 19.1, p <0.001). There was a significant association between PH and decreased 5-year survival (adjusted log-rank p value = 0.006), with severe PH being associated with the poorest survival (adjusted hazard ratio 2.4, 95% CI 1.3 to 4.2, p = 0.003). In conclusion, severe PH in patients with severe AS is associated with increased rates of in-hospital adverse events and decreased 5-year survival after AVR.

Cerebrovascular response to continuous cold perfusion and hypothermic circulatory arrest

OBJECTIVE Clinical and laboratory studies have documented changes in cerebrovascular resistance after hypothermic circulatory arrest, both with and without adjunctive cerebral perfusion modalities. This study was designed to clarify whether these changes are due to cerebral edema, resistance vessel abnormalities, or alterations in the cerebral microcirculation. METHODS Four mature swine underwent hypothermic circulatory arrest for 60 minutes, and 7 mature swine underwent cold cerebral perfusion for 60 minutes to simulate antegrade selective perfusion. All were rewarmed and weaned from cardiopulmonary bypass. Pial vascular diameter and reactivity were measured in vivo through a cranial window and ex vivo in an organ chamber; cerebral microvascular endothelium was studied in culture for release of vasoactive mediators. Cerebral water content was recorded. RESULTS Cold perfusion caused pial arteriole and venule constriction, whereas hypothermic circulatory arrest alone caused pial arteriole and venule dilatation. Cold perfusion caused a temporal loss of endothelium-dependent vasodilatation, most notably to bradykinin. Hypothermic circulatory arrest caused a loss of nitric oxide-mediated endothelium-dependent vasodilatation. Endothelium-independent vasoreactivity remained intact in both groups. Endothelial cells from the cold group had a vasoconstrictive secretory phenotype, whereas endothelial cells from the hypothermic circulatory arrest group had a vasodilatory phenotype. Cerebral water content was the same in both groups. CONCLUSION The increase in cerebrovascular resistance observed after cold cerebral perfusion is caused by resistance vessel constriction and may be promoted by an altered microcirculation. Hypothermic circulatory arrest alone is associated with endothelium-dependent vasoparesis. Both could contribute to cerebral injury in the early hours after operation.

Blood conservation strategies in Jehovah's Witness patients undergoing complex aortic surgery: a report of three cases.

Thoracic aortic surgery in Jehovah’s Witness (JW) patients presents a unique challenge to the surgeon and anesthesiologist because the patient’s religious-based objection to the use of allogeneic blood products impacts surgical technique and intraoperative fluid management methodology. Successful thoracic aortic repair without the transfusion of allogeneic blood products is especially difficult because the outcome of this type of surgery usually depends on the transfusion of relatively large amounts of allogeneic blood products.1 To maintain a treatment course congruent with the JW patient’s religious beliefs, alternative methods of blood conservation should be used by the anesthesiologist.2 Two cases are presented in which a JW patient underwent repair of a thoracoabdominal aneurysm (TAA), and a third case of a JW patient who underwent repair of an aortic root and arch aneurysm. All cases used acute normovolemic hemodilution (ANH) and underwent successful surgical repair without the use of allogeneic blood products.

A novel model of blunt thoracic aortic injury: a mechanism confirmed?

BACKGROUND There is no consensus on the mechanism of traumatic injury to the thoracic aorta and no reproducible animal model. Advances in injury scene analysis suggest that lateral and oblique force vectors cause aortic injury. We hypothesized that the spectrum of aortic injury could be reproduced in an animal model by application of an obliquely directed load to the pressurized aorta. METHODS Graded air impulses of 80, 100, 110, and 120 pounds per square inch (PSI) were delivered to the descending thoracic aorta of 19 swine with a novel pneumatic device. Aortic isthmus strain was recorded with microminiature probes. Gross and microscopic injury was recorded with digital photography. RESULTS The spectrum of human aortic injury was reproduced in this model. Deep injuries to the aortic media were common. The majority of injuries occurred within the region of the isthmus. Impulse pressure of 120 PSI caused transections, whereas lower impulse pressure resulted in less severe injuries. Aortic isthmus strain was greater in the animals exposed to 120 PSI than those receiving lower PSI (19.6 +/- 4.9% vs. 8.7 +/- 2.5%, p = 0.067). CONCLUSIONS Direct loading of the pressurized descending thoracic aorta causes isthmus injury secondary to aortic wall strain. Deep medial lesions are common and could propagate soon after injury to form pseudoaneurysms. A critical load is required to cause complete uncontained transection with exsanguination, which may have relevance to injury scene death.

Mycotic arch aneurysm and aortoesophageal fistula in a patient with melioidosis

Aortoesophageal fistula due to an aortic arch aneurysm is a rare entity with an extremely high mortality. There are few reports of successfully managed cases and even fewer of long term survival. We report a case of an aortoesophageal fistula resulting from a mycotic pseudoaneurysm of the distal aortic arch in a patient with melioidosis, its surgical management, and outcome.

A simple trick for repairing coronary pseudoaneurysm complicating a Bentall operation

Coronary pseudoaneurysms are a known complication of the Bentall wrap-inclusion method of composite valve grafting. We describe two cases to illustrate a straightforward technique for repair and prevention of coronary pseudoaneurysm formation.

Does Use of Bilateral Internal Mammary Artery Grafting Reduce Long-Term Risk of Repeat Coronary Revascularization?: A Multicenter Analysis

Background: Although previous studies have demonstrated that patients receiving bilateral internal mammary artery (BIMA) conduits during coronary artery bypass grafting have better long-term survival than those receiving a single internal mammary artery (SIMA), data on risk of repeat revascularization are more limited. In this analysis, we compare the timing, frequency, and type of repeat coronary revascularization among patients receiving BIMA and SIMA. Methods: We conducted a multicenter, retrospective analysis of 47 984 consecutive coronary artery bypass grafting surgeries performed from 1992 to 2014 among 7 medical centers reporting to a prospectively maintained clinical registry. Among the study population, 1482 coronary artery bypass grafting surgeries with BIMA were identified, and 1297 patients receiving BIMA were propensity-matched to 1297 patients receiving SIMA. The primary end point was freedom from repeat coronary revascularization. Results: The median duration of follow-up was 13.2 (IQR, 7.4–17.7) years. Patients were well matched by age, body mass index, major comorbidities, and cardiac function. There was a higher freedom from repeat revascularization among patients receiving BIMA than among patients receiving SIMA (hazard ratio [HR], 0.78 [95% CI, 0.65–0.94]; P=0.009). Among the matched cohort, 19.4% (n=252) of patients receiving SIMA underwent repeat revascularization, whereas this frequency was 15.1% (n=196) among patients receiving BIMA (P=0.004). The majority of repeat revascularization procedures were percutaneous coronary interventions (94.2%), and this did not differ between groups (P=0.274). Groups also did not differ in the ratio of native versus graft vessel percutaneous coronary intervention (P=0.899), or regarding percutaneous coronary intervention target vessels; the most common targets in both groups were the right coronary (P=0.133) and circumflex arteries (P=0.093). In comparison with SIMA, BIMA grafting was associated with a reduction in all-cause mortality at 12 years of follow-up (HR, 0.79 [95% CI, 0.69–0.91]; P=0.001), and there was no difference in in-hospital morbidity. Conclusions: BIMA grafting was associated with a reduced risk of repeat revascularization and an improvement in long-term survival and should be considered more frequently during coronary artery bypass grafting.

Bioprosthetic valve durability: the proof is in the pudding.

Dystrophic calcification is the Achilles heel of biomaterial durability. Conventional fixation of collagen-rich biomaterial is performed with glutaraldehyde, which cross-links proteins to provide material stability and reduce xenograft antigenicity. Glutaraldehyde, however, is cytotoxic and is associated with a postfixation tissue environment that predisposes to calcification. Devitalized cells release calcium into the interstitial compartment of the tissue that binds to free aldehyde groups and exposed acidic phospholipids, contributing to stiffening and ultimate failure of physiologic function. Although controversial, residual antigenicity is also thought to play a role in glutaraldehyde-fixed biomaterial degeneration. Commercial valve companies seek ways to improve bioprosthetic valve durability by reducing long-term uptake of calcium. Anticalcification strategies have resulted in improved valve durability when compared with tissue fixation alone. Anticalcification strategies most commonly entail treatment with detergents to remove calcium-binding phospholipids or treatment with compounds that alter the structure of exposed aldehyde groups. Because the calcification process is thought to be multifactorial, combining different treatment modalities to develop synergy in an anticalcification strategy is proposed to extend the life of component biomaterials. Flameng and colleagues present an industry-financed study of a new proprietary tissue preservation technology that tests a synergistic anticalcification strategy in an ovine model of bovine pericardial mitral valve replacement. The test valves are compared with commercially available valves treated with phospholipid depletion alone (Edwards 6900P, XenologiX; Edwards Lifesciences, Irvine, Calif). The novel treatment also uses this same method of phospholipid and cell debris removal, a solution of ethanol and surfactant. The new technology introduces specific methodology to remove free aldehyde groups, although the procedure is not described. It is unknown if this represents the same

Management strategies for acute coronary occlusion associated with CoreValve transcatheter aortic valve replacement.

Transcatheter aortic valve replacement (TAVR) has become an effective treatment option for high risk or prohibitive surgical risk symptomatic severe aortic stenosis (AS) patients. Though TAVR has been widely adopted, complications are possible and management strategies are critical to procedural success. TAVR associated acute coronary artery occlusion is rare: in the largest case series, the incidence was 0.9 % [1] but potentially fatal. Herein, we describe three cases of acute coronary artery occlusion subsequent to Medtronic CoreValve implantation and potential management strategies that were employed successfully.