State of the art in neuroprotection during acute type A aortic dissection repair.

Temporary (TND) or permanent neurologic dysfunctions (PND) represent the main neurological complications following acute aortic dissection repair. The aim of our experimental and clinical research was the improvement and update of the most common neuroprotective strategies which are in present use. HYPOTHERMIC CIRCULATORY ARREST (HCA): Cerebral metabolic suppression at the clinically most used temperatures (18-22°C) is less complete than had been assumed previously. If used as a 'stand-alone' neuroprotective strategy, cooling to 15-20°C with a jugular SO(2) ≥ 95% is needed to provide sufficient metabolic suppression. Regardless of the depth of cooling, the HCA interval should not exceed 25 min. After 40 min of HCA, the incidence of TND and PND increases, after 60 min, the mortality rate increases. ANTEGRADE SELECTIVE CEREBRAL PERFUSION (ASCP): At moderate hypothermia (25-28°C), ASCP should be performed at a pump flow rate of 10ml/kg/min, targeting a cerebral perfusion pressure of 50-60mmHg. Experimental data revealed that these conditions offer an optimal regional blood flow in the cortex (80±27ml/min/100g), the cerebellum (77±32ml/min/100g), the pons (89±5ml/min/100g) and the hippocampus (55±16ml/min/100g) for 25 minutes. If prolonged, does ASCP at 32°C provide the same neuroprotective effect? CANNULATION STRATEGY: Direct axillary artery cannulation ensures the advantage of performing both systemic cooling and ASCP through the same cannula, preventing additional manipulation with the attendant embolic risk. An additional cannulation of the left carotid artery ensures a bi-hemispheric perfusion, with a neurologic outcome of only 6% TND and 1% PND. NEUROMONITORING: Near-infrared spectroscopy and evoked potentials may prove the effectiveness of the neuroprotective strategy used, especially if the trend goes to less radical cooling. CONCLUSION: A short interval of HCA (5 min) followed by a more extended period of ASCP (25 min) at moderate hypothermia (28°C), with a pump flow rate of 10ml/kg/min and a cerebral perfusion pressure of 50 mmHg, represents safe conditions for open arch surgery.

Case of left atrial metastasis of a sarcomatoid carcinoma.

Metastatic tumor involvement of the heart may occur with all types of primary neoplasms. Right atrial cardiac metastases following vena cava extension from renal cell carcinoma are well recognized, while a left atrial appearance is extremely rare. We report on a patient who developed a left atrial mass originating from the lower right pulmonary vein after successful resection of a renal cell carcinoma with sarcomatoid areas by right-sided nephrectomy. To our knowledge, this is the first described case of this type of pancytokeratin-expressing tumor in the literature so far.

Changes in regional cerebral blood flow under hypothermic selective cerebral perfusion.

OBJECTIVE: Currently the most frequently used perfusion technique during aortic arch surgery to prevent cerebral damage is hypothermic selective cerebral perfusion (SCP). Changes in cerebral blood flow (CBF) are known to occur during these procedures. We investigated regional changes of CBF under conditions of SCP in a porcine model. METHODS: In this blinded study, twenty-three juvenile pigs (20 - 22 kg) were randomized after cooling to 20 degrees C on CPB. Group I (n = 12) underwent SCP for 90 minutes, while group II (n = 11) underwent total body perfusion. Fluorescent microspheres were injected at seven time-points to calculate total and regional CBF. Hemodynamics, intracranial pressure (ICP), cerebrovascular resistance (CVR) and oxygen consumption were assessed. Tissue samples from the neocortex, cerebellum, hippocampus and brain stem were taken for a microsphere count. RESULTS: CBF decreased significantly (p = 0.0001) during cooling, but remained at significantly higher levels with SCP than with CPB throughout perfusion (p < 0.0001) and recovery (p < 0.0001). These findings were similar among all regions of the brain, certainly at different levels. Neocortex CBF decreased 50%, whereas brain stem and hippocampus CBF decreased by only 25 % during total body perfusion. All four regions showed 10 - 20% less CBF in the post-CPB period. CBF during SCP did not fall by more than 20% in any analysed region. The hippocampus turned out to have the lowest CBF, while the neocortex showed the highest CBF. CONCLUSION: SCP improves CBF in all regions of the brain. Our study characterizes the brain specific hierarchy of blood flow during SCP and total body perfusion. These dynamics are highly relevant for clinical strategies of perfusion.

[Brief losses of consciousness of unknown origin. The contribution of echocardiography and of Holter monitoring]. / Les pertes de connaissance bréves de nature inconnue. Apport de l'échocardiographie et du Holter.

67 patients presented with a syncope of unknown origin following the usual exploration and were the subject of a more elaborated study: echocardiography (echo 2D) and Holter. 3.5 per cent of the Holter recordings enabled to ascribe to the heart the cause of the syncope. More than half of the Holters disclosed abnormalities of the cardiac rhythm leading to an anti-arrhythmic therapy in some cases, even when the cardiac origin of the loss of consciousness (LC) could not be confirmed. Echocardiograms could not lead to the diagnosis and less than one fourth of them disclosed abnormalities. In a developing study (14.8 +/- 8.7 months) that was carried out, 3 out of 4 patients did not present with any more LC; 3 died (6%) and 9 (18%) had LC again. On the other hand, in 5 patients (10%) a diagnosis could be evoked at the end of this follow-up. This study confirms the difficulties of diagnosis of this group of syncope of unknown etiology, as evidenced by the low results of intense and costly explorations and the little information obtained, even after a follow-up of more than 1 year.

[Contribution of echocardiography and Holter monitoring to the diagnosis of occult sources of cerebral embolism]. / Apport de l'échocardiographie et du Holter au diagnostic des sources occultes d'embolie cérébrale.

112 echocardiographies and 91 long-term Holter recordings were performed looking for an emboligenic cardiac lesion in patients in sinus rhythm and free of any major carotid atherosclerosis. The results were evaluated in relation to the emboligenic potential of the lesions observed. 5 positive results were obtained (4.46%) on echocardiography (3 aneurysms of the interatrial septum, 1 myxoma and 1 endocarditis) and 10 positive results (10.99%) were demonstrated on the Holter monitor. Among the 45 (40.18%) echocardiographic anomalies capable of constituting a cardiac site of origin of emboli, there were 18 cases of dilatation or hypertrophy of the left chambers of the heart, 13 cases of calcification of the aortic valve, 8 cases of prolapse of the mitral valve and 8 cases of calcification of the mitral ring. Finally, 55.35 per cent of the echocardiographic examinations and 52.74 per cent of the Holter examinations were found to be normal. Although the yield of these examinations is low, the anomalies discovered were definitely responsible for the cerebral emboli and could only have been demonstrated by such investigations.