TOF-tube, a new protection for acceleromyography, compared with the TOF-Guard/TOF-Watch arm board.

Neuromuscular blockade monitoring at the adductor pollicis has become easier using acceleromyography. In order to guarantee a reliable analysis of its acceleration, the thumb movement has to be free and protected from external influences. To this end, we describe here-in two hand fixation- and protection-devices for use with acceleromyography. After a bolus of 0.3 mg/kg rocuronium, we compared acceleromyography data obtained simultaneously on both hands with, on one side, the cumbersome TOF-Guard/TOF-Watch arm board, and the smaller and handier TOF-tube on the other. Results showed little differences between the two devices. Yet, a short and clinically irrelevant delay was observed for TOF-tube data during recovery. This was probably caused by a difference in thumb position and repositioning technique. In conclusion, the more convenient TOF-tube can be used as well as the TOF-Guard/TOF-Watch arm board in daily clinical practice.

Effects of acute decrease in systemic afterload on accuracy of Doppler-derived left ventricular rate of pressure rise measurement in anesthetized patients.

OBJECTIVES: This study was designed to describe exactly the effects of acute decrease in systemic afterload on the accuracy of Doppler-derived left ventricular rate of pressure rise (LV DeltaP/Delta(t)) measurements compared with other routinely used indices of systolic function. METHODS: Twelve patients scheduled for coronary artery bypass grafting were studied. After induction of anesthesia (T0), afterload was modified by incremental administrations of nicardipine (T1-4). At each step of the procedure, thermodilution-derived cardiac index, left ventricular (LV) fractional area change, and LV DeltaP/Delta(t) were measured, and systemic vascular resistances were calculated. RESULTS: During the procedure, the systemic vascular resistances decrease averaged 13.4%. Systemic vascular resistances were correlated with LV DeltaP/Delta(t) (r = 0.843, P =.003) but inversely correlated with cardiac index (r = -0.782, P =.005) and LV fractional area change (r = -0.887, P =.003). CONCLUSION: In conclusion, and inversely to cardiac index or LV fractional area change, LV DeltaP/Delta(t) does not overestimate LV contractility in the presence of an acute decrease in systemic afterload.

Doppler-derived left ventricular rate of pressure rise determination in presence of severe acute mitral regurgitation in pigs.

Doppler-derived left ventricular (LV) rate of pressure rise (Dop LV DeltaP/Deltat) is described as an index of LV performance in the presence of mitral regurgitation (MR). This study was designed to define more accurately the accuracy of the method in the presence of severe MR. Ten pigs were anesthetized and monitored. MR was gradually created. At each grade of MR, preload was manipulated with the intent of modifying LV end-diastolic area value within a range of +/-20%. Concurrently, the mean left atrial pressure (LAP) was recorded, MR was quantified by the mitral to aortic velocity-time integral ratio (mitroaortic VTI ratio), Dop LV DeltaP/Deltat was calculated, and peak LV dP/dt was derived from LV catheterism data. During the procedure Dop LV DeltaP/Deltat gradually underestimated peak LV dP/dt. This difference was correlated to the mean LAP (P < 10(-5)) and mitroaortic VTI ratio (P < 10(-5)) and became clinically significant when the mean LAP was superior to 21 mm Hg.

Patent foramen ovale and implantable cardioverter defibrillator.

A case of patent foramen ovale opening was observed concomitantly to a defibrillation threshold determination in the setting of an internal cardioverter defibrillator implantation. The subsequent transient right-to-left shunt was confirmed by a peroperative transoesophageal echocontrast study. The underlying mechanism of this incident may be related to a transient reversal of the interatrial gradient, due to the pre-existence of pulmonary hypertension and tricuspid regurgitation, associated with ongoing mechanical ventilation and modifications of intracardiac pressures regimen secondary to the succeeding ventricular tachyarrhythmia and defibrillation. Paradoxical embolism can be an aetiology for neurologic injury during internal cardioverter defibrillator implantation.

Doppler-derived left ventricular rate of pressure rise and inotropic requirements during mitral valve surgery.

BACKGROUND: The estimation of left ventricular (LV) contractility is difficult in the presence of significant mitral regurgitation (MR). Prediction of LV performance after MR repair is even more problematic. The intraoperative Doppler-derived LV rate of pressure rise (LV delta P/delta t) analyzed before cardiopulmonary bypass (CPB) was presumed to be a useful predictive parameter for LV performance. Therefore, its relation to perioperative inotropic requirements (PIR) necessary for separation from CPB after surgical MR repair was investigated. METHODS: Twenty-eight patients scheduled for surgical MR repair fulfilled the selection criteria. Pre-CPB LV delta P/delta t, pre-CPB echocardiographic LV fractional area change (LV FAC), and pre-CPB thermodilution-derived cardiac index (CI) were recorded. After MR repair, separation from CPB was performed with regard to standardized guidelines. PIR during the first 60 minutes following separation were recorded. RESULTS: Pre-CPB LV delta P/delta t could be assessed in 22 patients. Pre-CPB LV delta P/delta t was 882 +/- 450 mmHg/sec, pre-CPB LV FAC was 49% +/- 9%, and pre-CPB CI was 2.0 +/- 0.2 L/kg/min. Pre-CPB LV delta P/delta t was significantly correlated with pre-CPB LV FAC (r = 0.56), and with pre-CPB CI (r = 0.72). Inotropic support was necessary in 16 patients (73%), and was best predicted by the pre-CPB LV delta P/delta t, by means of logistic regression (p = 0.026). CONCLUSIONS: Doppler-derived LV delta P/delta t was assessable in most patients with severe chronic MR, and was the best intraoperative predictive parameter of post-CPB inotropic requirements after surgical MR repair.

Hemodynamic benefit of optimizing atrioventricular delay after cardiopulmonary bypass.

BACKGROUND: Shortening of atrioventricular delay (AVD) by sequential cardiac pacing has been proposed to improve hemodynamics in patients with end-stage heart failure. In addition, optimization of prolonged AVD may be associated with a decrease of presystolic mitral insufficiency. The aim of this study was to explore the incidence of prolonged AVD during the early postcardiopulmonary bypass (CPB) period and to evaluate the hemodynamic benefit of its shortening by using sequential cardiac pacing. METHODS: Fifty consecutive patients scheduled for coronary artery bypass grafting were prospectively screened. AVD was measured immediately after separation from CPB. Patients presenting with AVD greater than or equal to 200 ms entered the study. Sequential cardiac pacing was introduced with programmed AVD starting at 80 ms and randomly increased by steps of 20 ms until resumption of native anterograde atrioventricular node conduction. Cardiac index (CI) was derived from transesophageal echocardiographic data during each step of this procedure. RESULTS: Nineteen patients were included. Median native AVD was 220 ms. Median optimal AVD was 140 ms. Mean native CI (CI-nat) was 2.59 +/- 0.42 L/min/m2. Mean optimal CI (CI-opt) was 3.12 +/- 0.45 L/min/m2. CI-opt/CI-nat was 1.20 +/- 0.07. CI-opt/CI-nat was significantly inversely correlated with preoperative left ventricular ejection fraction (r = -0.83). CONCLUSIONS: Prolonged AVD is a common occurrence after CPB. Its artificial shortening by sequential cardiac pacing is always associated with a significant increase of CI. The magnitude of this hemodynamic improvement is inversely correlated with preoperative left ventricular ejection fraction.

Persistent left superior vena cava: transoesophageal echocardiographic findings and surgical strategies.

Two cases of casual discovery of persistent left superior vena cava during cardiac surgery are reported. Diagnoses were suspected at the time of peroperative transoesophageal echocardiography in the first case, and of preoperative fluoroscopy during a Swan-Ganz catheter insertion procedure in the second case. For both patients, a peroperative echo contrast study permitted to confirm the anomaly before initialization of cardiopulmonary bypass. Embryology, echocardiographic findings and surgical management, including cardioplegia delivering and left upper venous system drainage, are reviewed.