Shuzo Oshita

Role of Left Atrial Appendage in Left Atrial Reservoir Function as Evaluated by Left Atrial Appendage Clamping During Cardiac Surgery

We evaluated the role of left atrial appendage (LAA) in the left atrial (LA) reservoir function by assessing the changes in LA flow dynamics after LAA clamping during cardiac surgery. The subjects were 8 patients who had undergone coronary artery bypass grafting (CABG) and 7 who had undergone mitral valvular surgery due to mitral regurgitation. We recorded transmitral, pulmonary venous and LAA flow velocity patterns by intraoperative transesophageal pulsed Doppler echocardiography, monitoring LA pressure before and 5 minutes after LAA clamping. The maximal LAA area was significantly greater, and the peak late diastolic LAA emptying flow velocity was significantly lower before LAA clamping in the mitral regurgitation group than in the CABG group. In both groups, the peak early and late diastolic transmitral and pulmonary venous flow velocities significantly increased, and the peak second systolic pulmonary flow velocity significantly decreased during LAA clamping. There were no significant changes in heart rate and systemic systolic blood pressure during LAA clamping, whereas mean LA pressure and maximal LA dimension significantly increased in both the groups. The LA pressure-volume relation during ventricular systole shifted upward and to the left during LAA clamping, and the slope was steeper in the MR group than in the CABG group. We conclude that the LAA is more compliant than the LA main chamber, and plays an important role in LA reservoir function in the presence of LA pressure and/or volume overload.

Central nervous system complications after cardiac surgery: a comparison between coronary artery bypass grafting and valve surgery.

Central nervous system (CNS) complications (disturbance of consciousness, focal motor deficits, and seizures) after coronary artery bypass grafting (CABG) and cardiac valve surgery were studied retrospectively. The incidence of CNS complications was significantly more frequent in CABG (11%, 71/638) than in valve surgery (7%, 24/345). Major contributory factors of CNS complications were preexisting cerebrovascular disease and cardiopulmonary bypass time. In comparison to previous reports, older age, hypertension, diabetes mellitus, and cerebrovascular disease were more common in the patients undergoing CABG. The preexisting cerebrovascular disease and prolonged cardiopulmonary bypass time probably increase the risk of cerebral embolism and/or cerebral hypoperfusion. We conclude that patients undergoing CABG surgery are at greater risk for neurological damage in comparison to those undergoing valve surgery.

Effects of tocainide and lidocaine on the transmembrane action potentials as related to external potassium and calcium concentrations in guinea-pig papillary muscles

SummaryEffects of lidocaine and tocainide on transmembrane potentials were studied in isolated guineapig papillary muscles, superfused with modified Tyrodes solution containing either 5.4, 2.7, 10.0 or 8.1 mmol/l potassium concentration, [K]0. The last solution applied contained either 1.8 (normal [Ca]0) or 7.2 mmol/l [Ca]0) (high [Ca]0). The concentrations of lidocaine and tocainide used were 18.5, 36.9 and 73.9 μmol/l and 43.7, 87.5 and 174.9 μmol/l in 5.4 mmol/l [K]0 solution and 36.9 and 87.5 μmol/l in the other solutions, respectively. At the driving rate of 1 Hz in 5.4 mmol/l [K]0 solution, both drugs produced dosedependently a reduction of maximum rate of rise of action potential (

Molecular mechanisms underlying ketamine-mediated inhibition of sarcolemmal adenosine triphosphate-sensitive potassium channels

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Clinically relevant concentrations of propofol have no effect on adenosine triphosphate-sensitive potassium channels in rat ventricular myocytes

), together with a prolongation of the relative refractory period.

Mechanisms of Impaired Glucose Tolerance and Insulin Secretion during Isoflurane Anesthesia

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