Jock N. McCullough

Can retrograde perfusion mitigate cerebal injury after particulate embolization? A study in a chronic porcine model

OBJECTIVE We assessed the impact on histologic and behavioral outcome of an interval of retrograde cerebral perfusion after arterial embolization, comparing retrograde cerebral perfusion with and without inferior vena caval occlusion with continued antegrade perfusion. METHODS Sixty Yorkshire pigs (27 to 30 kg) were randomly assigned to the following groups: antegrade cerebral perfusion control; antegrade cerebral perfusion after embolization; retrograde cerebral perfusion control; retrograde cerebral perfusion after embolization; retrograde cerebral perfusion with inferior vena cava occlusion, retrograde cerebral perfusion with inferior vena cava occlusion control, and retrograde cerebral perfusion with inferior vena cava occlusion after embolization. After cooling to 20 degrees C, a bolus of 200 mg of polystyrene microspheres 250 to 750 (microm diameter (or saline solution) was injected into the isolated aortic arch. After 5 minutes of antegrade cerebral perfusion, 25 minutes of antegrade cerebral perfusion, retrograde cerebral perfusion, or retrograde cerebral perfusion with inferior vena cava occlusion was instituted. After the operation, all animals underwent daily assessment of neurologic status until the time of death on day 7. RESULTS Aortic arch return, cerebral vascular resistance, and oxygen extraction data during retrograde cerebral perfusion showed differences, suggesting that more effective flow occurs during retrograde cerebral perfusion with inferior vena cava occlusion, which also resulted in more pronounced fluid sequestration. Microsphere recovery from the brain revealed significantly fewer emboli after retrograde cerebral perfusion with inferior vena cava occlusion. Behavioral scores showed full recovery in all but one control animal (after retrograde cerebral perfusion with inferior vena cava occlusion) by day 7 but were considerably lower after embolization, with no significant differences between groups. The extent of histopathologic injury was not significantly different among embolized groups. Although no histopathologic lesions were present in either the antegrade cerebral perfusion control group or the retrograde cerebral perfusion control group, mild significant ischemic damage occurred after retrograde cerebral perfusion with inferior vena cava occlusion even in control animals. CONCLUSIONS Although effective washout of particulate emboli from the brain can be achieved with retrograde cerebral perfusion with inferior vena cava occlusion, no advantage of retrograde cerebral perfusion with inferior vena cava occlusion after embolization is seen from behavioral scores, electroencephalographic recovery, or histopathologic examination; retrograde cerebral perfusion with inferior vena cava occlusion results in greater fluid sequestration and mild histopathologic injury even in control animals. Retrograde cerebral perfusion with inferior vena cava occlusion shows clear promise in the management of embolization, but further refinements must be sought to address its still worrisome potential for harm.

Surgical techniques. Aortic arch and deep hypothermic circulatory arrest: real-life suspended animation.

Surgical reconstruction of the aortic arch is a complex procedure requiring careful preoperative analysis of the pathology and forethought toward surgical approach. Development of surgical techniques has brought dramatic improvement survival and reduction of neurological events associated with these procedures, yet significant morbidity is still encountered. New approaches to the patient with these pathologies include antegrade and retrograde perfusions to the brain. Continued research into physiology of hypothermic circulatory arrest offers the promise of pharmacological protection of the brain during aortic reconstruction and potentially development of therapeutic modalities to treat and limit ischemic brain damage.

A comparison of complete blood replacement with varying hematocrit levels on neurological recovery in a porcine model of profound hypothermic (<5°C) circulatory arrest

Profound hypothermia (<5 degrees C) may afford better neurological protection after circulatory arrest; however, there are theoretical concerns related to microcirculatory sludging of blood components at these ultra-low temperatures. We hypothesized that at temperatures <5 degrees C, complete blood replacement results in superior neurological outcome. Twelve Yorkshire pigs (30 kg) underwent thoracotomy, cardiopulmonary bypass (CPB), and were randomly assigned to one of three target hematocrits during circulatory arrest: 0%, 5%, 15%. Hextend (6% hetastarch in a balanced electrolyte vehicle) was used for the CPB prime and as an exchange fluid. Animals were cooled to a temperature <5 degrees C, underwent 1-h circulatory arrest, and were warmed to 35 degrees C with administration of blood to increase the hematocrit to >25% before separation from CPB. The primary outcome, peak postoperative neurobehavioral score, was compared between groups. The 0% group (mean +/- SD) had significantly (P: < 0.02) better neurobehavioral scores than the 5% and 15% groups (6.0 +/- 2.9 vs 1.3 +/- 1.0 and 1.5 +/- 0.6) respectively. Other variables (e.g., intracranial pressure) were similar between groups. In a porcine model of profound hypothermia (<5 degrees C) and circulatory arrest, complete blood replacement resulted in superior neurological outcome. This finding suggests that at ultralow temperatures, the presence of some blood component (e.g., erythrocytes, leukocytes) may be deleterious.

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.

Comparative effectiveness of coronary artery bypass grafting versus percutaneous coronary intervention in a real-world Surgical Treatment for Ischemic Heart Failure trial population

Objective There are no prospective randomized trial data to guide decisions on optimal revascularization strategies for patients with multivessel coronary artery disease and reduced ejection fraction. In this analysis, we describe the comparative effectiveness of coronary artery bypass grafting (CABG) versus percutaneous coronary intervention (PCI) in this patient population. Methods A multicenter, retrospective analysis of all CABG (n = 18,292) and PCIs (n = 55,438) performed from 2004 to 2014 among 7 medical centers reporting to the Northern New England Cardiovascular Disease Study Group. After applying inclusion and exclusion criteria from the Surgical Treatment for Ischemic Heart Failure trial, there were 955 CABG and 718 PCI patients with an ejection fraction ≤ 35% and 2‐ or 3‐vessel disease. Inverse probability weighting was used for risk adjustment. The primary end point was all‐cause mortality. Secondary end points included rates of 30‐day mortality, stroke, acute kidney injury, and incidence of repeat revascularization. Results The median duration of follow‐up was 4.3 years (range, 1.59‐6.71 years). CABG was associated with improved long‐term survival compared with PCI after risk adjustment (hazard ratio, 0.59; 95% confidence interval, 0.50‐0.71; P < .01). Although CABG and PCI had similar 30‐day mortality rates (P = .14), CABG was associated with a higher frequency of stroke (P < .001) and acute kidney injury (P < .001), whereas PCI was associated with a higher incidence of repeat revascularization (P < .001). Conclusions Among patients with reduced ejection fraction and multivessel disease, CABG was associated with improved long‐term survival compared with PCI. CABG should be strongly considered in patients with ischemic cardiomyopathy and multivessel coronary disease.

Reply to the Editor— Leftward on left anterior oblique is not always septal!

We appreciate the interesting comments made by Drs Contractor and Cooper. We agree that using fluoroscopy to confirm septal placement of right ventricular pacing leads is notoriously difficult. Placement of pacing leads in the inferoseptal or anteroseptal junction, or the right ventricular free wall, appears to be a mechanism for perforation in many cases. Although a computed tomography scan is helpful, lead imaging artifact can make it difficult to evaluate the exact location of the lead. In our case, at surgery, the lead location was confirmed below the left anterior descending artery (LAD) and exiting from the free wall of the left ventricle. We felt that given the location of the lead perforation and relatively young age of the patient, an open surgical approach would be the safest andmost controlled option. After opening the sternum and visualizing the lead exiting the left ventricle lateral to the LAD we felt our approach was prudent. While a nonoperative approach may have been feasible, the potential for bleeding or injury to the LAD could have resulted in a fatal outcome. Our patient was discharged home with no adverse events on postoperative day 4.

Right ventricular lead perforation through the septum, left ventricle, and pleura, managed by an open surgical approach

Introduction Cardiac perforation of the right ventricle is an uncommon but potentially serious complication of transvenous pacemaker implantation. When it occurs, right ventricular (RV) perforation is typically seen through the apex. Here, we describe a case of a pacemaker lead that perforated through the RV septum and then the left ventricle, discuss the management of this complication, and provide a brief review of the literature.

The evolution of minimally invasive cardiac surgery: from minimal access to transcatheter approaches

The field of minimally invasive cardiac surgery has undergone rapid transformation over recent years. In this review, we provide a summary of the most current evidence supporting the use of minimally invasive aortic and mitral valve replacement techniques, as well as transcatheter approaches for aortic and mitral valve disease. As an adjunct, the use of robotically assisted coronary bypass surgery and hybrid coronary revascularization procedures is discussed. In order to obtain optimal patient outcomes, a collaborative, heart-team approach between cardiac surgeons and interventional cardiologists is necessary.

Outcomes with moderate aortic stenosis and impaired left ventricular function: prelude to a randomized trial?

The natural history of severe, symptomatic aortic stenosis (AS) has been well characterized, with most studies demonstrating a mortality rate of 50% at 2 years once patients develop symptoms of left ventricular (LV) systolic dysfunction (1,2).

Optimal revascularization for left main coronary artery disease—coronary artery bypass grafting versus percutaneous coronary intervention

Coronary artery bypass grafting (CABG) has historically been the standard of care for management of left main coronary artery disease (LMCAD). Studies have demonstrated a survival advantage when CABG has been compared to optimal medical management alone in LMCAD (1-3).