Steven L. Lansman

Peripheral Extracorporeal Membrane Oxygenation: Comprehensive Therapy for High-Risk Massive Pulmonary Embolism

BACKGROUND Although commonly reserved as a last line of defense, experienced centers have reported excellent results with pulmonary embolectomy for massive and submassive pulmonary embolism (PE). We present a contemporary surgical series for PE that demonstrates the utility of peripheral extracorporeal membrane oxygenation (pECMO) for high-risk surgical candidates. METHODS Between June 2005 and April 2011, 29 patients were treated for massive or submassive pulmonary embolism, with surgical embolectomy performed in 26. Four high-risk patients were placed on pECMO, established by percutaneously cannulating the right atrium through a femoral vein and perfusing by a Dacron graft anastomosed to the axillary artery. A small, extracorporeal, rotary assist device was used, interposing a compact oxygenator in the circuit, and maintaining anticoagulation with heparin. RESULTS Extracorporeal membrane oxygenation was weaned in 3 of 4 patients after 5.3 days (5, 5, and 6), with normalization of right ventricular dysfunction and pulmonary artery pressure (44.0 ± 2.0 to 24.5 ± 5.5 mm Hg) by ECHO. Follow-up computed tomographies showed several peripheral, nearly resorbed emboli in 1 case and complete resolution in 2 others. The fourth patient, not improving after 10 days, underwent surgery where an embolic liposarcoma was extracted. For all 29 cases, hospital and 30-day mortality was 0% and all patients were discharged, with average postoperative length of stay of 15 days for embolectomy and 17 days for pECMO. CONCLUSIONS Heparin therapy with pECMO support is a rapid, effective option for patients who might benefit from pulmonary embolectomy but are at high risk for surgery.

Arginase 1 contributes to diminished coronary arteriolar dilation in patients with diabetes

Arginase 1, via competing with nitric oxide (NO) synthase for the substrate L-arginine, may interfere with NO-mediated vascular responses. We tested the hypothesis that arginase 1 contributes to coronary vasomotor dysfunction in patients with diabetes mellitus (DM). Coronary arterioles were dissected from the right atrial appendages of 41 consecutive patients with or without DM (the 2 groups suffered from similar comorbidities), and agonist-induced changes in diameter were measured with videomicroscopy. We found that the endothelium-dependent agonist ACh elicited a diminished vasodilation and caused constriction to the highest ACh concentration (0.1 μM) with a similar magnitude in patients with (18 ± 8%) and without (17 ± 9%) DM. Responses to ACh were not significantly affected by the inhibition of NO synthesis with N(G)-nitro-L-arginine methyl ester in either group. The NO donor sodium nitroprusside-dependent dilations were not different in patients with or without DM. Interestingly, we found that the presence of N(G)-hydroxy-L-arginine (10 μM), a selective inhibitor of arginase or application of L-arginine (3 mM), restored ACh-induced coronary dilations only in patients with DM (to 47 ± 6% and to 40 ± 19%, respectively) but not in subjects without DM. Correspondingly, the protein expression of arginase 1 was increased in coronary arterioles of patients with DM compared with subjects without diabetes. Moreover, using immunocytochemistry, we detected an abundant immunostaining of arginase 1 in coronary endothelial cells of patients with DM, which was colocalized with NO synthase. Collectively, we provided evidence for a distinct upregulation of arginase 1 in coronary arterioles of patients with DM, which contributes to a reduced NO production and consequently diminished vasodilation.

Acute aortic syndrome.

The term acute aortic syndrome refers to a heterogeneous group of conditions that cause a common set of signs and symptoms, the foremost of which is aortic pain. Various pathologic entities may give rise to this syndrome, but the topic has come to focus on penetrating aortic ulcer and intramural hematoma and their relation to aortic dissection. Penetrating aortic ulcer is a focal atherosclerotic plaque that corrodes a variable depth through the intima into the media. Intramural hematoma is a blood collection within the aortic wall not freely communicating with the aortic lumen, with restricted flow. It may represent a subcategory of aortic dissection that manifests different behavior by virtue of limited flow in the false lumen. This article reviews the current literature regarding acute aortic syndrome, focusing on management options.

Selective cerebral perfusion: A review of the evidence

OBJECTIVE With the realization that hypothermia was neuroprotective, hypothermic selective antegrade cerebral perfusion was adopted by many surgical groups for aortic arch resection, prompting experimental and clinical studies to elaborate technical refinements and safe parameters of selective antegrade cerebral perfusion. We review the evidence for optimum management of perfusion pressure, flow, temperature, pH, hematocrit, and cannulation access. METHODS Underperfusion and overperfusion impair neurologic function after selective antegrade cerebral perfusion. Overperfusion--including excessive flow and pressure--is expressed experimentally as an increase in intracranial pressure, indicative of cerebral edema, and causes slow neurobehavioral recovery. As the safe limits of moderate and mild hypothermic selective antegrade cerebral perfusion are being explored in many aortic centers, the ischemic tolerance of the spinal cord during lower-body circulatory arrest becomes a new focus of concern. RESULTS Although a significant portion of the population has an incomplete circle of Willis, contralateral flow via extracranial collaterals has permitted the successful use of various cannulation techniques. Unilateral perfusion is adequate for short-term (<40 minutes) selective antegrade cerebral perfusion, even at higher temperatures (24 °C-28 °C). However, if prolonged periods of selective antegrade cerebral perfusion are anticipated, evidence suggests that better cerebral protection is obtained with bilateral selective antegrade cerebral perfusion. CONCLUSIONS On the basis of these experimental and clinical studies, certain recommendations for the use of nonpulsatile selective antegrade cerebral perfusion can be made.

Vascular complication can be minimized with a balloon-expandable, re-collapsible sheath in TAVR with a self-expanding bioprosthesis

This study evaluates the feasibility and safety of a balloon‐expandable, re‐collapsible sheath for TAVR patients, including those with small iliofemoral access (≤5.0 mm).

Aortic surgery in pregnancy

&NA; Pregnancy engenders changes in hemodynamics and the aortic wall that make a woman more susceptible to aortic dilatation and dissection. This is particularly true of women with aortic dilatation and an aortopathy, including the inherited fibrillinopathies, bicuspid aortic valve, and Turner syndrome. Women in these risk groups may be served best by undergoing elective aortic surgery before becoming pregnant. However, some women present during pregnancy with significant aortic dilatation, rapid expansion, or aortic dissection, and strategies to deal with these situations, while optimizing maternal and fetal outcomes, change as gestation progresses. This review summarizes the approaches to the management of aortic diseases and the conduct of aortic surgery in pregnancy.

Calcium Resection to Relieve Left Main Coronary Obstruction in Transcatheter Aortic Valve Replacement

Coronary obstruction during transcatheter aortic valve replacement (TAVR) is a rare yet life‐threatening complication. Emergent resection of the obstructing calcium is a quick and simple method to restore coronary perfusion in TAVR over emergency CABG. doi: 10.1111/jocs.12752 (J Card Surg 2016;31:315–317)

Malperfusion in Type A Dissection: Consider Reperfusion First

Acute type A aortic dissection (ATAAD) is a vascular catastrophe, with a mortality of 1% per hour for the first 48 hours without surgical intervention. Of the diverse causes of morbidity and mortality associated with ATAAD, malperfusion, which complicates 20%-50% of cases, is particularly lethal. Although malperfusion can affect any vascular bed, this review focuses on the 3 most devastating: coronary, cerebral, and visceral malperfusion syndromes (MPS). Essentially, there are 3 methods of restoring flow to malperfused areas: central repair, fenestration, and direct revascularization of affected arteries. Of these, emergency central aortic repair is the accepted primary strategy, as it most expeditiously eliminates the risk of rupture, and accordingly, our protocol is to transfer ATAAD cases directly to the operating room. However, central repair is not necessarily the most expedient strategy for resolving malperfusion, and in some cases, malperfusion persists despite central repair. At some point, with certain cases of severe malperfusion, the mortality from end organ damage exceeds the mortality risk of rupture and recent reports suggest that these cases may be best managed by emergency reperfusion of the affected vascular bed, followed by central repair.

Peripheral Veno-arterial Extracorporeal Membrane Oxygenation for Treatment of Ischemic Shock

Extracorporeal membrane oxygenation (ECMO), often referred to as extracorporeal life support (ECLS), provides temporary support to critically ill patients who cannot maintain their respiratory and/or circulatory function. A basic circuit composed of cannula, tubing, a pump, oxygenator, and heat exchanger; there are two approaches: veno-venous (VV) ECMO for solely respiratory support, and veno-arterial (VA) ECMO for cardiac support, cardio-respiratory support, or undifferentiated etiology support. Since first use in 1971 [1], ECMO circuits have improved in design and function [2–4]. This review focuses on contemporary insertion techniques and management considerations, which have improved clinical outcomes in VA ECMO, specifically, peripherally inserted VA ECMO for cardiogenic shock secondary to ischemic presentation.

The Aortic Root in Acute Type A Dissection: Rationale and Outcome for an Increased Use of Root Replacement

Management of the aortic root in acute type A dissection remains challenging and controversial and the appropriate strategy depends on a number of patient and anatomic factors. Valve resuspension is simple and easy to perform and may be appropriate in a majority of patients without aortic root pathology. Moderate to severe aortic insufficiency, annuloaortic ectasia with annular diameter >27 mm, connective tissue disorders such as Marfan’s syndrome, and the use of gelatin-resorcinol-formaldehyde glue in aortic root repair, have all been identified as risk factors for proximal reoperation. In the presence of the above anatomic risk factors or significant root pathology, an aortic root replacement should be performed. A biological valve-graft conduit can be used if systemic anticoagulation is a concern. In experienced hands and in stable patients with normal aortic valve anatomy, a valve-sparing reimplantation procedure may be considered.