Hypothermic circulatory arrest with "low flow" lower body perfusion: an experimental feasibility study of microcirculatory parameters.

BACKGROUND: To avoid extended cardiopulmonary bypass (CPB), moderate temperatures are commonly accepted for hypothermic circulatory arrest (HCA), thereby jeopardizing organ protection. Distal aortic perfusion may be an option, but supportive experimental data is missing. METHODS: Eight juvenile pigs (36 ± 2 kg) were cooled to 30 °C followed by 60 min of HCA with 50 min of low flow (LF) lower body perfusion. Multimodal monitoring was used to measure overall metabolism, hemodynamics and microcirculation of the terminal ileum. The animals were observed for four hours following reperfusion. Organs were harvested for histopathological evaluation. RESULTS: During LF perfusion, initially elevated l-lactate levels decreased subsequently ( P < 0.05). Capillary blood flow decreased during cooling to 50 % baseline levels ( P = 0.03), but remained stable under LF conditions. Parameters indicative of reduced liver and kidney function were slightly elevated at the end of the experiment, but still within normal ranges. CONCLUSION: Under moderate hypothermia, low flow perfusion seems to provide adequate protection for the lower body organs. Microcirculatory parameters during perfusion as well as lactate levels within normal ranges throughout the experiments further confirm the concept.

Treatment of acute aortic dissection type A (AADA): technical considerations.

Aortic dissection is one of the the most common and lethal catastrophes involving the aorta. Speedy diagnosis, as well as appropriate therapy are essential for survival of the patients. Because the clinical presentation in patients suffering AADA can differ substantially, discussion concerning specific surgical therapy remains controversial. This implies questions regarding the treatment of the aortic root as well as the aortic arch and the proximal descending aorta. The current manuscript raises important issues regarding surgical treatment of AADA patients which are discussed in the light of the institutional policy in the author's department.

[Thoracic aortic surgery with circulatory arrest and cold cerebral perfusion]. / Thorakale Aortenchirurgie unter moderater Hypothermie und kalter Gehirnperfusion.

BACKGROUND: This study was undertaken to identify pre- and perioperative risk factors to mortality and permanent neurological dysfunction (PND) and temporary neurological dysfunction (TND) in a large patient cohort, all operated under moderate hypothermic circulatory arrest (HCA) and selective antegrade cerebral perfusion (SACP) in a single centre. PATIENT AND METHODS: Between November 1999 and March 2006, 319 patients at a median age of 65 years (range 21-86, 201 male) underwent elective aortic arch surgery with moderate HCA at 25 degrees C and additional SACP at 14 degrees C. Sixty-nine had additional coronary artery bypass grafts or valve procedures. Ninety-four (29%) had total arch repair. Statistical analysis was carried out to determine the risk factors for 30-day mortality as well as for TND and PND. RESULTS: Overall mortality was 7.8% (15% in cases with repeat surgery vs 4.8% in nonrepeats, P=0.002). Twenty-seven (8.5%) suffered from PND, and six (22%) died during hospital stay (P=0.004). There was TND detected in 32 patients (10%). Stepwise logistic regression revealed age (P=0.001, OR 1.09/year), repeat surgery (P=0.008, OR 5.04), preoperative neurological events (P=0.004, OR 3.44), CAD (P=0.051, OR 3.58), and cardiopulmonary bypass duration (P<0.001, OR 1.01/min) as risk factors for mortality. The PND was associated with preoperative renal insufficiency (P=0.026, OR 3.34) and operation duration (P<0.001, OR 1.01/min), whereas TND occurred in patients with coronary artery disease (P=0.04, OR 2.41), and prolonged cardiopulmonary bypass duration (P=0.05, OR 1.01/min). CONCLUSION: Thoracic aortic surgery including aortic arch using HCA and SACP can be performed with excellent results in elective patients, especially those without previous surgery. Nevertheless PND is associated with high hospital mortality. Neurological complications seem to be strongly associated with general atherosclerotic changes as well as the extent of surgery.