Joel S. Corvera

Adenosine in myocardial protection in on-pump and off-pump cardiac surgery

Adenosine is most well known for its potent vasodilation of the vasculature. However, it also promotes glycolysis, and activates potassium-sensitive adenosine triphosphate (K(ATP)) channels. Adenosine also strongly inhibits neutrophil function such as superoxide anion production, protease release, and adherence to coronary endothelial cells. Hence adenosine attenuates ischemic injury as well as neutrophil-mediated reperfusion injury. Adenosine has also been implicated in the cardioprotective phenomenon of ischemic preconditioning. Accordingly experimental evidence shows that adenosine reduces postischemic injury when administered before ischemia and at the onset of reperfusion. Clinical studies in cardiology and cardiac surgery show cardioprotective trends with adenosine treatment but the effects are not as dramatic as those reported by experimental studies.

Pretreatment with phenoxybenzamine attenuates the radial artery's vasoconstrictor response to α-adrenergic stimuli

BACKGROUND Although the radial artery bypass conduit has excellent intermediate-term patency, it has a proclivity to vasospasm. We tested the hypothesis that brief pretreatment of a radial artery graft with the irreversible adrenergic antagonist phenoxybenzamine attenuates the vasoconstrictor response to the vasopressors phenylephrine and norepinephrine compared with the currently used papaverine/lidocaine. METHODS Segments of human radial artery grafts were obtained after a 30-minute intraoperative pretreatment with a solution containing 20 mL of heparinized blood, 0.4 mL of papaverine (30 mg/mL), and 1.6 mL of lidocaine (1%). The segments were transported to the laboratory and placed into a bath containing Krebs-Henseleit solution and 10, 100, or 1000 micromol/L phenoxybenzamine or vehicle. The segments were tested in organ chambers for contractile responses to increasing concentrations of phenylephrine and norepinephrine (0.5-15 micromol/L). RESULTS Contractile responses to 15 micromol/L phenylephrine in control radial artery segments averaged 44.2% +/- 9.1% of the maximal contractile response to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated contraction to 15 micromol/L phenylephrine (32.1% +/- 5.9%; P =.22), but 1000 micromol/L phenoxybenzamine completely abolished radial artery contraction (-7.2% +/- 4.4%; P <.001). The effect of 10 and 100 micromol/L phenoxybenzamine on attenuating vasocontraction was intermediate between 1000 micromol/L phenoxybenzamine and papaverine/lidocaine. Responses to 15 micromol/L norepinephrine in control radial artery segments averaged 54.7% +/- 7.5% of maximal contraction to 30 mmol/L KCl. Papaverine/lidocaine modestly attenuated the contraction response of radial artery segments (35.6% +/- 5.1%; P =.04). In contrast, 1000 micromol/L phenoxybenzamine showed the greatest attenuation of norepinephrine-induced contraction (-10.5% +/- 2.0%; P <.001). CONCLUSIONS A brief pretreatment of the human radial artery bypass conduit with 1000 micromol/L phenoxybenzamine completely attenuates the vasoconstrictor responses to the widely used vasopressors norepinephrine and phenylephrine. Papaverine/lidocaine alone did not block vasoconstriction to these alpha-adrenergic agonists.

The ARCH Projects: design and rationale (IAASSG 001)

OBJECTIVE A number of factors limit the effectiveness of current aortic arch studies in assessing optimal neuroprotection strategies, including insufficient patient numbers, heterogenous definitions of clinical variables, multiple technical strategies, inadequate reporting of surgical outcomes and a lack of collaborative effort. We have formed an international coalition of centres to provide more robust investigations into this topic. METHODS High-volume aortic arch centres were identified from the literature and contacted for recruitment. A Research Steering Committee of expert arch surgeons was convened to oversee the direction of the research. RESULTS The International Aortic Arch Surgery Study Group has been formed by 41 arch surgeons from 10 countries to better evaluate patient outcomes after aortic arch surgery. Several projects, including the establishment of a multi-institutional retrospective database, randomized controlled trials and a prospectively collected database, are currently underway. CONCLUSIONS Such a collaborative effort will herald a turning point in the surgical management of aortic arch pathologies and will provide better powered analyses to assess the impact of varying surgical techniques on mortality and morbidity, identify predictors for neurological and operative risk, formulate and validate risk predictor models and review long-term survival outcomes and quality-of-life after arch surgery.

Perfusion-assisted direct coronary artery bypass provides early reperfusion of ischemic myocardium and facilitates complete revascularization

BACKGROUND Perfusion-assisted direct coronary artery bypass (PADCAB) was developed to initiate early reperfusion of grafted coronary artery segments during off-pump operations to resolve episodes of myocardial ischemia and avoid its sequelae. This case series outlines intraoperative findings and clinical outcomes of our first year clinical experience with PADCAB. METHODS From November 1999 to November 2000, 169 PADCAB and 358 off-pump coronary artery bypass procedures were performed at the Emory University Hospitals. The decision to use PADCAB was predicated on surgeon preference. Perfusion pressure and flow, amount of intracoronary nitroglycerin, and total perfusion time and volume were recorded at the time of operation. RESULTS One off-pump coronary artery bypass patient required emergent conversion to cardiopulmonary bypass. Two PADCAB patients had ischemic ventricular arrhythmias during target vessel occlusion that resolved once active perfusion had begun. Perfusion pressure in PADCAB grafts was on average 44% higher than mean arterial pressure (p < 0.001). Nitroglycerin, infused locally by PADCAB, was used in 67 patients to resolve ischemic episodes and increase initial coronary flows. The mean number of diseased coronary territories and grafts placed was 2.8 +/- 0.5 and 3.4 +/- 0.7, respectively, in the PADCAB group, and 2.3 +/- 0.8 and 2.7 +/- 1.0, respectively, in the off-pump coronary artery bypass group (p < 0.001 for both comparisons). More PADCAB patients received lateral wall grafts than off-pump coronary artery bypass patients (83.4% vs 59.4%; p < 0.001). Hospital death and postoperative myocardial infarction were not different between groups. CONCLUSIONS PADCAB can provide suprasystemic perfusion pressures and a means to add vasoactive drugs to target coronary vessels. PADCAB provides early reperfusion of ischemic myocardium and facilitates complete revascularization of severe multivessel coronary artery disease.

Open Repair of Chronic Aortic Dissections Using Deep Hypothermia and Circulatory Arrest

BACKGROUND There has been great enthusiasm for thoracic endograft repair of chronic thoracic or thoracoabdominal aortic dissection (ChAD) given the low operative morbidity and mortality. However long-term results are unknown and early reintervention is common. This study examines the early and late results of open repair of ChAD using deep hypothermia and circulatory arrest (DHCA). METHODS From January 1995 to December 2009, 343 patients had open repair of descending thoracic or thoracoabdominal aneurysms using DHCA. Of these individuals, 93 patients had open repair of ChAD with DHCA. All patients undergoing elective procedures underwent preoperative cardiac catheterization. Lumbar drains were not placed preoperatively. Visceral or renal artery bypass was performed in 20% of patients. Supraaortic branches were bypassed in 14% of patients. RESULTS Mean age was 60 ± 14 years. Men composed 77% of the cohort. Aortic replacement encompassed the descending aorta in 29% of patients, type I thoracoabdominal repair was performed in 25% of patients, type II thoracoabdominal repair was performed in 40% of patients, and arch replacement was performed in 24% of patients. Operative mortality was 2.2%, renal failure requiring dialysis was 0%, paralysis occurred in 1.1% of patients, stroke occurred in 1.1% of patients, prolonged intubation was needed in 9.7% of patients, and tracheostomy was needed in 2.2% of patients. Postoperative length of stay was 10.5 ± 7.6 days. One-, 3-, 5-, and 10-year survival rates were 93%, 90%, 79%, and 61%, respectively. Reintervention was necessary in 2.2% of patients for graft infection, in 2.2% of patients for anastomotic pseudoaneurysm, and in 4.4% of patients for growth of a distal aortic aneurysm. CONCLUSIONS Open repair of ChAD with DHCA has low operative morbidity and mortality. Long-term survival is very good with low rates of reintervention. Endovascular repair of ChAD does not have proven short- or long-term efficacy.

Total Arch and Descending Thoracic Aortic Replacement by Left Thoracotomy

BACKGROUND The hybrid treatment of transverse aortic arch pathologies with supraaortic debranching and endovascular repair is associated with significant morbidity and death and lacks long-term follow-up. The traditional two-stage open surgical approach to extensive arch and descending thoracic aneurysms carries a significant interval mortality rate. We report the results of a single-stage technique of total arch and descending thoracic aortic replacement by a left thoracotomy. METHODS From January 1995 to February 2011, 426 patients underwent thoracic or thoracoabdominal aneurysm repair, of which a highly selected group of 27 patients underwent total arch replacement with descending thoracic or thoracoabdominal aortic replacement. All procedures were performed with hypothermic circulatory arrest and selective antegrade cerebral perfusion. Two patients required transverse division of the sternum. Two patients had emergency or urgent operations. Five patients had concomitant coronary artery bypass, and 1 had concomitant mitral valve replacement. RESULTS There were no hospital deaths, no cerebrovascular accidents, and one instance of transient spinal cord ischemia. Three patients had acute renal failure not requiring hemodialysis. Intubation in 5 patients exceeded 48 hours, and 1 patient needed tracheostomy. Two patients required reexploration for postoperative bleeding. Survival at 1, 3, and 5 years was 95%, 78%, and 73%, respectively. CONCLUSIONS Replacement of the total arch and descending thoracic aorta by a left thoracotomy provides excellent short-term and long-term results for the treatment of extensive arch and thoracic aortic pathology, without the need for a second-stage operation. Other cardiac pathologies, such as left-sided coronary disease and mitral valve disease, can be addressed concurrently.

Acute aortic syndrome.

Acute aortic syndrome (AAS) is a term used to describe a constellation of life-threatening aortic diseases that have similar presentation, but appear to have distinct demographic, clinical, pathological and survival characteristics. Many believe that the three major entities that comprise AAS: aortic dissection (AD), intramural hematoma (IMH) and penetrating aortic ulcer (PAU), make up a spectrum of aortic disease in which one entity may evolve into or coexist with another. Much of the confusion in accurately classifying an AAS is that they present with similar symptoms: typically acute onset of severe chest or back pain, and may have similar radiographic features, since the disease entities all involve injury or disruption of the medial layer of the aortic wall. The accurate diagnosis of an AAS is often made at operation. This manuscript will attempt to clarify the similarities and differences between AD, IMH and PAU of the ascending aorta and describe the challenges in distinguishing them from one another.

Transcatheter Aortic Valve Replacement Versus Aortic Valve Bypass: A Comparison of Outcomes and Economics.

BACKGROUND Transcatheter aortic valve replacement (TAVR) is currently offered to patients who are high-risk candidates for conventional surgical aortic valve replacement. For the past 37 years, off-pump aortic valve bypass (AVB) has been used in elderly patients at our center for this similarly high-risk group. Although TAVR and AVB were offered to similar patients at our center, comparisons of clinical outcomes and hospital economics for each strategy were not reported. METHODS We reviewed the clinical and financial records of 53 consecutive AVB procedures performed since 2008 with the records of 51 consecutive TAVR procedures performed since 2012. Data included demographics, hemodynamics, The Society of Thoracic Surgeons (STS) risk score, extent of coronary disease, and ventricular function. Follow-up was 100% in both groups. Hospital financial information for both cohorts was obtained. Mean risk score for the TAVR group was 10.1% versus 17.6% for AVB group (p < 0.001). RESULTS Kaplan-Meier hospital rates of 3- and 6-month survival and of 1-year survival were 88%, 86%, 81%, and 61% and 89%, 83%, 83%, and 70% for the TAVR and AVB groups, respectively (p = 0.781). Two patients who had undergone TAVR had a procedure-related stroke. The one stroke in an AVB recipient was late and not procedure related. At discharge, mild and moderate perivalvular and central aortic insufficiency were present in 31% and 16% of TAVR recipients, respectively; no AVB valve leaked. Transvalvular gradients were reduced to less than 10 mm Hg in both groups. The average hospital length of stay for the AVB-treated patients was 13 days, and it was 9 days for the TAVR-treated patients. Median hospital charges were

Best surgical option for thoracoabdominal aneurysm repair - the open approach.

253,000 for TAVR and

Optimal dose and mode of delivery of Na+/H+ exchange-1 inhibitor are critical for reducing postsurgical ischemia-reperfusion injury

158,000 for AVB. Mean payment to the hospital was