Alterations in arterial properties detected by pulse wave velocity and pulse wave analyses in patients with hypercholesterolemia are controversial. Therefore, we used an animal model of atherosclerosis to test the potential of arterial mechanical properties indexed by aortic input impedance (Zin) as markers for early detection of atheromatous lesions in the aorta. In 12-month-old anesthetized Kurosawa and Kusanagi-Hypercholesterolemic Rabbits (KHC; n=15), pressure and flow were measured at the ascending aorta during sinus rhythm and random pacing. We confirmed histologically in previous studies that early-stage atheromas developed in the aorta by this age. Age-matched Japanese White rabbits(JW;n=13) had no overt atheroma. High-resolution Zin derived from random beating data was characterized by a lower ratio of the first local maximum to minimum |Zin| (1.36±0.26 vs. 2.08±0.33; p<10-5) accompanied by more delayed phases over a range between 6 and 8 Hz (−0.35±0.21 vs. −0.05±0.15 radian;p=0.0002); and a lower characteristic impedance (2.30±0.67 vs. 2.92±0.59 mmHg·s·kg BW/ml;p=0.016) in KHC than in JW rabbits. We concluded that frequency-specific changes in Zin are sensitive hemodynamic markers that can detect early-stage atheromatous lesions in the aorta. High-resolution Zin analysis is essential and useful for detecting such frequency-dependent findings.
Purpose ; The thoracic bioimpedance method (TBI) is thought to be useful to measure cardiac output continuously and non-invasively. In this study, the usefulness of TBI using BioZ.comTM (CardioDynamics International Corp.) in cardiac surgery was examined in comparison with continuous thermodilution methods (CCO) using VigilanceTM (Edwards Lifesciences LLC). Methods; Cardiac output was continuously measured by both TBI and CCO in 10 patients (ASA risk II) undergoing elective coronary artery bypass grafting. Data were collected (1) after intubation but before incision; (2) after surgery; and (3)12hrs after surgery, when hemodynamics were stable. Results; Cardiac output measured by TBI and CCO were ranging (1) 1.7to 2.3l·min-1·kg-1 and 1.0 to 2.7 l·min-1·kg-1, (2) 1.1 to 3.1l·min-1·kg-1 and 1.9 to 4.0l·min-1·kg-1, (3) 1.7 to 3.1l·min-1·kg-1 and 2.3 to 3.9l·min-1·kg-1, respectively. And, correlations between cardiac output measured by TBI (Y) and CCO (X) were (1)y=0.891+0.408x;r=0.366, (2) y=0.771+0.478x;r=0.559, and (3)y=0.592+1. 057x;r=0.573. Conclusions; In cardiac surgery, TBI might be useless to measure cardiac output because it did not have a good correlation with CCO.
A conventional reoperation via sternotomy approach is associated with a higher risk of heart injury as compared with first time operation. We have applied a minimally invasive cardiac surgery (MICS) for valve reoperation in order to minimize dissection of sternal adhesions. We evaluated MICS for mitral reoperation in this report. We retrospectively analyzed 20 patients (group R) who underwent mitral reoperation via partial lower hemisternotomy(PLH) and 66 patients (group I) who underwent first time operation via PLH from July 1997 through March 2002. The two groups took similar operative and postoperative course. Only the time of surgery was significantly longer in the group R. There were neither any operative deaths nor any postoperative major complications in both groups. PLH for mitral reoperation were performed safely and obtained operative outcome similar to PLH for first time mitral operation. We conclude that PLH will be an alternative approach for mitral reoperation.
Detailed mechanisms underlying the genesis of myocardial cell hypertrophy caused by long-term mechanical overload have not yet been fully understood. In the present study, we investigated effects of the increased sympathetic nervous tone, which is considered to occur in order to maintain the normal cardiac output when the heart is mechanically overloaded, on cell hypertrophy. To do this, myocardial cells isolated from adult rats were cultured under electrical field stimulation, and the effects of an agonist of sympathetic receptors, and the frequency and intensity of cell contraction on the mass of the cells were investigated by measuring the total protein content and the contents of α-actin and β-myosin. The cell hypertrophy was induced by stimulating β-adrenoceptors, and was enhanced by concurrent cell contraction (electrical stimulation). These changes were associated with the increase in the contents of actin and myosin, indicating that the cell hypertrophy induced in the present study may be an adaptive response against the mechanical overload if it would occur in vivo. On the other hand, the cell contraction itself significantly increased the contents of actin and myosin. The present study suggested that the increased sympathetic nervous tone induced hypertrophy by stimulating β-adrenoceptors together with the increase in contractile proteins through mechanoreceptor activation.
A 72 year-old woman had a traumatic fracture of the neck of the right femur. At the time of surgical repair of the fractured femur, she suddenly developed cardiopulmonary arrest when turned to the left lateral position for spinal anesthesia. Because of unsuccessful cardiopulmonary resuscitation, PCPS was immediately started. Meantime a diagnosis of pulmonary embolism was made by thoracic CT scan. Then an effective t-PA thrombolysis combined with heparin anticoagulation were carried out, and she was successfully rescued. After uneventful weaning of PCPS and insertion of a permanent IVC filter, the hip operation was performed 21 post-hospital days. From the above experience, we realized that PCPS is essential for saving critically ill patients with PTE and also deep vein thrombosis as a cause of PTE should deeply be paid attention.