Impaired coronary contraction to phenylephrine after cardioplegic arrest in diabetic patients.

BACKGROUND: We have previously found that hyperkalemic cardioplegic arrest in the setting of cardiopulmonary bypass (CP/CPB) is associated with impairment of the coronary arteriolar response to phenylephrine in nondiabetic (ND) patients. We hypothesized that diabetes may alter coronary arteriolar response to alpha-1 adrenergic agonist in the setting of CP/CPB. In this study, we further investigated the effects of diabetes on the altered coronary arteriolar response to phenylephrine in patients undergoing cardiac surgery. METHODS: Coronary arterioles (90-150 µm in diameter) were harvested pre- and post-CP/CPB from the ND and diabetic mellitus (DM) patients (n = 8/group) undergoing cardiac surgery. In-vitro microvascular reactivity was examined in response to phenylephrine. The protein expression/localization of the alpha-1 adrenergic receptors in the atrial myocardium was measured by Western blotting and immunohistochemistry. RESULTS: Phenylephrine (10-9 to 10-4 M) induced a dose-dependent contractile response in both ND and DM vessels pre- and post-CP/CPB. There was no significant difference in the pre-CP/CPB contractile responses to phenylephrine between ND and DM groups. The post-CP/CPB contractile response was significantly diminished in both ND and DM groups compared with the respective pre-CP/CPB response (P < 0.05 versus pre-CP/CPB). This diminished contractile response was more pronounced in vessels from DM patients compared with vessels from ND patients (P < 0.05 versus ND). There were no significant differences in the protein expression of alpha-1A and alpha-1B receptors in the atrial myocardium between the ND and DM groups or tissue harvested pre- or post-CP/CPB. CONCLUSIONS: Diabetes is associated with a decreased contractile response of coronary arterioles to phenylephrine in the setting of CP/CPB versus that observed in ND patients. This alteration may contribute to the vasomotor dysfunction of coronary microcirculation seen early after CP/CPB in patients with diabetes.

Long-Term Outcomes of External Repair as a Rescue Operation for Atrioventricular Groove Disruption.

BACKGROUND: Atrioventricular groove disruption (AVGD) is an uncommon but lethal complication of mitral valve operations associated with mortality approaching 90%. Traditionally, an "internal" repair is performed requiring prosthesis explantation, complete atrioventricular groove reconstruction using a patch positioned from within the cardiac cavity, and subsequent prosthesis reimplantation. This is a massive undertaking that is usually unsuccessful. We examine the utility of an alternative, "external" approach for rescue of AVGD. METHODS: A retrospective review was conducted of consecutive patients with AVGD after mitral operations at 3 North American medical centers. All patients underwent external repair as a rescue procedure. The external repair technique was conducted on cardiopulmonary bypass using direct suturing or felt-reinforced suturing, or both, of the atrioventricular groove. This was supplemented as needed with applications of BioGlue (CryoLife, Kennesaw, GA), external bovine pericardial patch, left atrial buttress, and coronary bypass grafting of the circumflex circulation. RESULTS: Between 1995 and 2015, 3,071 mitral valve operations resulted in 13 AVGDs (incidence, 0.42%). Average patient age was 75.2 years (range, 59-90 years), and 77% (10 of 13) were women. The 30-day mortality was 15.4% (2 of 13), and hospital mortality was 23.1% (3 of 13). Survival rates at 1, 3, and 5 years were 72.7%, 72.7%, and 44.4%, respectively. Seven patients are currently still alive and remain in no greater than New York Heart Association Functional Classification II. A stable pseudoaneurysm subsequently developed in 2 patients. CONCLUSIONS: The incidence of AVGD after mitral operations is low. Despite an older population with more tissue fragility, the external approach represents an effective, alternative repair technique for rescue of AVGD with encouraging results.

Long-term survival after use of internal thoracic artery in octogenarians is gender related.

OBJECTIVE: The goal of this study is to assess the benefits of a left internal thoracic artery as a bypass conduit in octogenarians undergoing elective coronary artery bypass grafting. We hypothesize that there is no survival advantage and that outcome may be gender related. METHODS: In a retrospective analysis of 1141 octogenarians (aged >80 years) undergoing isolated coronary artery bypass grafting from 1996 to 2012, patients were divided into 2 groups: Group I (coronary artery bypass grafting-left internal thoracic artery) included 870 patients (339 female/531 male), and group II (coronary artery bypass grafting-saphenous vein graft) included 271 patients (131 female/140 male). RESULTS: The overall 30-day mortality was 5.7%: 4.3% in group I and 7.0% in group II (P = .1). Group II had a lower trend of any postoperative complication (P = .05) and pneumonia (P = .05). When analyzed by gender, there were no discernable differences in long-term survival for male patients in group I (65% at 5 years and 29% at 10 years) versus male patients in group II (65% at 5 years and 31% at 10 years) (P = .2). However, survival was significantly greater for female patients in group I (70% at 5 years and 35% at 10 years) versus female patients in group II (63% at 5 years and 21% at 19 years) (P = .01). Multiple logistic and Cox regression analysis showed that left internal thoracic artery use is associated with improved survival in female patients (hazard ratio [HR], 0.72; confidence interval [CI], 0.56-0.93) but not in male patients (HR, 1.14; CI, 0.9-1.4). Advanced age was associated with an increased risk of mortality (HR, 1.08 per year; CI, 1.05-1.1). Both patient age (P = .01) and Society of Thoracic Surgeons-predicted 30-day mortality (P = .03) remain in the final model for 30-day mortality. The benefit of the left internal thoracic artery after coronary artery bypass grafting in octogenarians may be gender related. CONCLUSIONS: This study shows that the benefit of the left internal thoracic artery in the octogenarian population undergoing coronary artery bypass grafting may be gender related. For elderly female patients, the use of the left internal thoracic artery as a bypass conduit was associated with better long-term survival, whereas no significant difference was found among the male population. The use of the left internal thoracic artery was associated with a greater postoperative pulmonary morbidity for the study population as a whole. The present study does not refute the benefit of the left internal thoracic artery-left anterior descending graft, but instead distinguishes a subset who might benefit more.

Changes in microvascular reactivity after cardiopulmonary bypass in patients with poorly controlled versus controlled diabetes.

BACKGROUND: We investigated the effects of cardiopulmonary bypass (CPB) on peripheral arteriolar reactivity and associated signaling pathways in poorly controlled (UDM), controlled (CDM), and case-matched nondiabetic (ND) patients undergoing coronary artery bypass grafting (CABG). METHODS AND RESULTS: Skeletal muscle arterioles were harvested before and after CPB from the UDM patients (hemoglobin A1c [HbA1c]=9.0 ± 0.3), the CDM patients (HbA1c=6.3 ± 0.15), and the ND patients (HbA1c=5.2 ± 0.1) undergoing CABG surgery (n=10/group). In vitro relaxation responses of precontracted arterioles to endothelium-dependent vasodilators adenosine 5'-diphosphate (ADP) and substance P and the endothelium-independent vasodilator sodium nitroprusside (SNP) were examined. The baseline responses to ADP, substance P, and SNP of arterioles from the UDM patients were decreased as compared with microvessels from the ND or CDM patients (P<0.05). The post-CPB relaxation responses to ADP and substance P were significantly decreased in all 3 groups compared with pre-CPB responses (P<0.05). However, these decreases were more pronounced in the UDM group (P<0.05). The post-CPB response to SNP was significantly decreased only in the UDM group, not in the other 2 groups compared with pre-CPB. The expression of protein kinase C (PKC)-α, PKC-ß, protein oxidation, and nitrotyrosine in the skeletal muscle were significantly increased in the UDM group as compared with those of ND or CDM groups (P<0.05). CONCLUSIONS: Poorly controlled diabetes results in impaired arteriolar function before and after CPB. These alterations are associated with the increased expression/activation of PKC-α and PKC-ß and enhanced oxidative and nitrosative stress.

Midterm outcomes of patients undergoing aortic valve replacement after previous coronary artery bypass grafting.

OBJECTIVES: Redo cardiac surgery for aortic valve replacement (AVR) after previous coronary artery bypass grafting (CABG) is technically challenging and carries a high incidence of peri-operative complications. However, experience in the field continues to evolve generating reproducible, and increasingly safer results. We anticipate an increased future role for catheter-based valve procedures and review our operative results to maintain current surgical outcomes for comparison. METHODS: A retrospective review was conducted from 1996 through 2010 of patients undergoing AVR as a re-operation after previous CABG. Data were obtained through query of the Society of Thoracic Surgeons (STS) database and chart review. Patient outcomes were compared with STS-predicted risk scores. RESULTS: One hundred and thirty-two patients met inclusion criteria (male 83%, female 17%). Average age was 76 (± 7). Thirty-seven patients (28%) required concomitant CABG. Average ejection fraction was 45 (± 14). Comorbid conditions included: diabetes 37% (49/132), hypertension 87% (115/132), NYHA class III/IV 83% (110/132), smoking 51% (67/132), chronic obstructive pulmonary disease 21% (27/132), history of myocardial infarction 61% (80/132), renal failure 16% (21/132) and peripheral arterial disease 38% (50/132).Operative (30-day + hospital) mortality was 6.1% (8/132; 95% CI = 2.9-12.0%), and 30-day mortality was 3.8% (5/132; 95% CI = 1.4-9.1%). One, three and five-year survival rates were 86, 74 and 62%, respectively. Complication rates were as follows: re-operation for bleeding 2.3% (3/132), permanent stroke 0.8% (1/132), prolonged ventilator requirement 18.2% (24/132), deep sternal wound infection 0% (0/132; CI = 0.0-3.5%) and renal failure 9.1% (12/132; none required dialysis). The mean STS-predicted mortality risk score was 7.8% for 111 (applicable) patients for whom actual operative (30-day + hospital) mortality was 3.6%. CONCLUSIONS: Low initial operative mortality suggests that surgery is safe and reproducible. However, older age and multiple comorbidities in this patient population may significantly influence late outcomes. The data reported in this study: (i) support open surgical technique as a safe, reliable approach for redo AVR in patients who have undergone previous CABG, and (ii) add to the large body of evidence suggesting that STS scores overestimate risk.