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Early defibrillation clearly improves survival from malignant arrhythmia. However, in some cases the cause of death will only be altered from arrhythmic to nonarrhythmic. We evaluated the impact of left ventricular ejection fraction (LVEF) on trend and recovery profile of beat-to-beat cardiac output (CO) and mean arterial blood pressure (MAP) after successful defibrillation.We investigated 63 NYHA class I-III patients undergoing threshold testing in the course of insertion of an implantable cardioverter defibrillator (ICD) in monitored anaesthesia care. Preoperatively, LVEF was classified as either normal (50%), moderately (30-50%) or severely impaired (30%). CO and MAP were measured continuously throughout the implantation procedure.Arrest time and body mass index were not different between groups. CO in patients with severely and moderately reduced LVEF dropped 21% and 13% below baseline (P0.05), respectively. MAP also decreased by 26% and 17%, respectively. In contrast, 45% of patients with LVEF50% showed sympathetic activation that resulted in a 12% and 2% increase in mean values for CO and MAP, respectively. In relation to patients with LVEF50%, CO and MAP values were significantly higher after defibrillation (P0.05). Additionally, recovery of CO was prolonged in the groups with ventricular dysfunction (P0.05). Temporary post-shock pacing was observed in 40% of patients.A large number of ICD patients with restricted LVEF appears to lack the ability to quickly restore CO and MAP after successful defibrillation. Organ reperfusion may thus still be compromised.

To determine the impact of brief periods of cardiac arrest (CA) on regional cerebral oxygen saturation (rSO2) in patients with low left ventricular ejection fraction (LVEF30%).Prospective observational study.Cardiac surgery room at a university hospital.Seventy-seven consecutive patients undergoing elective implantation of a cardioverter/defibrillator in monitored anesthesia care. According to preoperative assessments, left ventricular function was classified as normal (LVEF50%), moderately impaired (LVEF 30%-50%), or severely reduced (LVEF30%).None.rSO2 was determined during threshold testing with concomitant induction of CA. In patients with LVEF30%, mean baseline rSO2 (59%) was already below the lower range of normal despite normal arterial blood pressure, heart rate, and arterial oxygen saturation. rSO2 increased by 6% after 6 L/min oxygen insufflation (p0.05) and dropped again in each group after CA, reaching a nadir after successful defibrillation. Patients with LVEF30% and baseline rSO263% exhibited the lowest values. They also showed the highest incidence (11%) of critical cerebral desaturations (i.e.,20% drop from baseline or rSO2 value50%). rSO2 in patients with LVEF30% was always below that determined in patients with LVEF30% (p0.05). There was a strong correlation between rSO2 values before CA and rSO2 nadir (p0.05). The drop in rSO2 was only moderately related to the brief CAs (p0.05).These findings demonstrate that severely compromised left ventricular pump function is associated with diminished rSO2. As these patients seem to be more susceptible to critical desaturations, they may be prone to severe tissue hypoxemia unless adequate oxygen delivery is reestablished rapidly. This may contribute to the poor neurologic outcome after successful resuscitation in patients with LVEF30%.

Approximately 10-20% of patients will not tolerate cross-clamping of the common carotid artery for carotid endarterectomy procedures. The most frequent causes of neurological deficits are either embolization of particulate matter or cerebral hypoperfusion. Insufficient blood flow through primary collaterals of the circle of Willis is the main reason for hypoperfusion that requires immediate shunt placement. Although excessive preoperative imaging is not indicated in many patients undergoing disobliteration of a stenosed internal carotid artery, there are some patients with particular anatomic constellations who would benefit from a more detailed preoperative work-up. In these cases, the specific risk should be evaluated prior to surgery in order to make plans for appropriate intraoperative management regarding neurologic monitoring and shunt insertion. As regional anesthesia permits early detection of ischemic symptoms, it is advantageous in these patients. We report a case where regional anesthesia allowed early detection of rapidly progressing signs of bi-hemispheric brain ischemia in a patient with diabetes and with at that time unknown severe abnormalities of the circle of Willis. Lack of adequate collateralization was detected only after surgery, in a combined perfusion-magnetic resonance imaging study. In symptomatic diabetics with low-grade stenosis of the internal carotid artery, preoperative assessment of the function of the circle of Willis may therefore be helpful in predicting any increased risk for intraoperative cerebral ischemia.

High-dose remifentanil (1-5 microg kg-1 min-1), commonly used for cardiac surgery, has been associated with muscle rigidity, hypotension, bradycardia, and reduced cardiac output. The aim of this study was to determine an optimal lower remifentanil dose, which should be accompanied by fewer adverse events, that still effectively suppresses haemodynamic responses to typical stressful stimuli (i.e. intubation, skin incision, and sternotomy).Total i.v. anaesthesia consisted of a target-controlled propofol (2 microg ml-1) and a remifentanil infusion. Forty patients were allocated to receive either a constant infusion of remifentanil at 0.1 microg kg-1 min-1 or up-titrations to 0.2, 0.3, or 0.4 microg kg-1 min-1, respectively, 5 min before each stimulus. Subsequently, changes in heart rate and mean arterial blood pressure were recorded for 8 min. Increases exceeding 20% of baseline were considered to be of clinical relevance. Patients who exhibited these alterations were termed responders.The number of responders was less with the two higher remifentanil dosages (P0.05) while propofol target doses could either be kept at the same level or even be reduced without affecting the plane of anaesthesia. Although single phenylephrine bolus had to be applied more frequently in these two groups (P0.05), no severe haemodynamic depression was observed.Remifentanil at 0.3 and 0.4 microg kg-1 min-1 in combination with a target-controlled propofol infusion in the pre-bypass period is well tolerated. It appears to mitigate potentially hazardous haemodynamic responses from stressful stimuli equally well as higher doses when compared with data from the literature.

To determine the degree of neurocognitive dysfunction after placement of internal cardioverter defibrillators (ICD) and its relationship to the extent of neuronal injury, we studied 42 patients undergoing ICD (n = 21) or pacemaker (PM) insertion (control patients, n = 21). The Mini Mental State Examination, the Trailmaking A test and the forward and backward Digit Span tests were used and P300 latencies were determined preoperatively and postoperatively. Serum neuron-specific enolase (NSE) was determined before and at the end of, as well as 2, 6, and 24 h after surgery. Preoperatively, PM patients scored worse in the Digit Span backward and the Trailmaking tests and showed prolonged P300 latencies. Postoperatively, the Digit Span backward scores declined and NSE levels increased only in the ICD group (P < or = 0.05). The difference between preoperative and postoperative Digit Span backward scores correlated with the increase in serum NSE levels (r2 = 0.3, P < or = 0.05). Moreover, P300 latencies increased in 13 of 17 ICD patients, but decreased in 7 of 10 PM patients (P < or = 0.05). PM patients even improved in the Trailmaking test (P < or = 0.05). Neuronal injury from even brief periods of global brain ischemia seems to be associated with deteriorating neurocognitive function.