Evaluation of left atrial function by the functional volume change curve derived from Doppler flow spectra

The objective of this study was to clarify the left atrial (LA) reservoir and booster pump function in patients with left ventricular (LV) diastolic dysfunction. To determine LA reservoir and booster pump function, a new algorithm to determine LA functional volume change curve (FVC) was developed from Doppler flow spectra of pulmonary venous flow and LV inflow by transthoracic echocardiography in 110 patients. Patients were classified into normal (N), and abnormal (AB) and pseudonormal (PN) groups on the basis of their Doppler flow patterns. From the indices of FVC, atrial reservoir volume (ARV), passive emptying volume (PEV) and active emptying volume (AEV) were obtained. ARV/stroke volume (SV) was increased in the AB group, but decreased in the PN group compared with N (N, 0.61+/-0.09; AB, 0.73+/-0.10; PN, 0.52+/-0.13, p<0.05). PEV/SV was significantly decreased in AB, but increased in PN compared with N (N, 0.27+/-0.07; AB, 0.19+/-0.07; PN, 0.31+/-0.18, p<0.05). AEV/SV was significantly increased in AB, but decreased in PN compared with N (N, 0.41+/-0.08; AB, 0.56+/-0.10; PN, 0.26+/-0.19, p<0.05). Thus, in patients with an abnormal relaxation pattern, the LA reservoir and booster pump function are augmented, but in patients with a pseudonormal pattern, both LA reservoir and booster pump function are deteriorated, suggesting a vulnerability to pulmonary congestion.

Dendritic spine geometry is critical for AMPA receptor expression in hippocampal CA1 pyramidal neurons

Dendritic spines serve as preferential sites of excitatory synaptic connections and are pleomorphic. To address the structure-function relationship of the dendritic spines, we used two-photon uncaging of glutamate to allow mapping of functional glutamate receptors at the level of the single synapse. Our analyses of the spines of CA1 pyramidal neurons reveal that AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid)-type glutamate receptors are abundant (up to 150/spine) in mushroom spines but sparsely distributed in thin spines and filopodia. The latter may be serving as the structural substrates of the silent synapses that have been proposed to play roles in development and plasticity of synaptic transmission. Our data indicate that distribution of functional AMPA receptors is tightly correlated with spine geometry and that receptor activity is independently regulated at the level of single spines.

Compensatory responses of left atrial conduit flow to atrial fibrillation with acute myocardial infarction in a canine model

The aim of this study was to examine the interaction of acute atrial fibrillation (Af) and acute myocardial infarction (AMI) on left atrial (LA) and left ventricular (LV) filling in atrioventricular (A-V) sequential paced, open chest, anesthetized dogs. Left atrial conduit function was determined from pulmonary venous flow (PVF) and detailed analysis of early diastolic flow with the use of micromanometers and transmitral Doppler echocardiography. We studied 8 dogs with regular ventricular rates to avoid the confounding effect of ventricular arrhythmia in Af. In the control stage, Af increased the diastolic PVF volume to the left atrium compared with that during regular A-V pacing (from 0.58 +/- 0.11 mL/beat to 0.70 +/- 0.13 mL/beat, P <.05), as a compensatory response to the impaired systolic PVF volume (from 0.56 +/- 0.12 mL/beat to 0.41 +/- 0.11 mL/beat, P <.05). As a result, cardiac output was maintained. However, in the AMI stage, Af decreased cardiac output (from 0.95 +/- 0.32 L/min to 0.80 +/- 0.23 L/min, P <.05 versus AMI with A-V pacing), and decreased diastolic PVF volume (from 0.46 +/- 0.13 mL/beat to 0.33 +/- 0.14 mL/beat, P <.05 versus AMI with A-V pacing). These changes were associated with a prolonged LV isovolumic pressure decay rate. Our study demonstrates that Af does not affect cardiac output in the setting of normal LV function at a controlled ventricular rate because enhanced LA conduit flow compensates for impaired LA reservoir function. In contrast, in the setting of AMI, the compensatory response to Af is attenuated because of abnormal LV relaxation, resulting in a decrease in cardiac output.

The importance of pulmonary venous flow measurement for evaluating left ventricular end-diastolic pressure in patients with coronary artery disease in the early stage of diastolic dysfunction

Transmitral flow pattern assessed by pulsed Doppler echocardiography is widely used to evaluate left ventricular end-diastolic pressure (LVEDP). A restrictive mitral flow pattern is well recognized as a finding of severely elevated LVEDP. On the other hand, an abnormal relaxation pattern can be interpreted many ways. For example, some patients who display an abnormal relaxation pattern have a mild impairment of left ventricular (LV) relaxation as a result of aging, and others have severely impaired LV diastolic function. To evaluate LVEDP in patients with abnormal relaxation mitral filling patterns, we studied 55 patients who had coronary artery disease with abnormal relaxation pattern who underwent elective cardiac catheterization. We recorded the transmitral and pulmonary venous flow velocity curves and measured the duration of the mitral A wave (MAd) and pulmonary venous reversal wave during atrial contraction (PAd). Positive correlations were found between PAd and LVEDP (r = 0.65, P <.01) and between PAd-MAd and LVEDP (r = 0.7, P <.0001); however, MAd was not significantly correlated with LVEDP. In conclusion, PAd must be measured for an accurate evaluation of LV end-diastolic pressure in patients with an abnormal relaxation pattern in the transmitral flow velocity curve.

Phosphorylation of proteins and apoptosis induced by c-Jun N-terminal kinase1 activation in rat cardiomyocytes by H(2)O(2) stimulation

Cytokines and various cellular stresses are known to activate c-Jun N-terminal kinase-1 (JNK1), which is involved in physiological function. Here, we investigate the activation of JNK1 by oxidative stress in H9c2 cells derived from rat cardiomyocytes. H(2)O(2) (100 microM) significantly induces the tyrosine phosphorylation of JNK1 with a peak 25 min after the stimulation. The amount of JNK1 protein remains almost constant during stimulation. Immunocytochemical observation shows that JNK1 staining in the nucleus is enhanced after H(2)O(2) stimulation. To clarify the physiological role of JNK1 activation under these conditions, we transfected antisense JNK1 DNA into H9c2 cells. The antisense DNA (2 microM) inhibits JNK1 expression by 80% as compared with expression in the presence of the sense DNA, and significantly blocks H(2)O(2)-induced cell death. Consistent with the decrease in cell number, we detected condensation of the nuclei, a hallmark of apoptosis, 3 h after H(2)O(2) stimulation in the presence of the sense DNA for JNK1. The antisense DNA of JNK1 inhibits the condensation of nuclei by H(2)O(2). Under these conditions, the H(2)O(2)-induced phosphorylation of proteins with molecular masses of 55, 72, and 78 kDa is blocked by treatment with the antisense DNA for JNK1 as compared with the sense DNA for JNK1. These findings suggest that JNK1 induces apoptotic cell death in response to H(2)O(2), and that the cell death may be involved in the phosphorylations of 55, 72, and 78 kDa proteins induced by JNK1 activation.

[Transverse myelopathy with renovascular hypertension caused by fibromuscular dysplasia]

An 18-year-old woman developed subacute transverse myelopathy with renovascular hypertension, hyperlipidemia, and proteinuria. Spinal magnetic resonance imaging(MRI) showed an intra-spinal cord lesion with severe spinal cord swelling at the C 2-Th 2 level. Increased plasma and cerebrospinal fluid interleukin-8(IL-8) levels and the presence of serum antineutrophil cytoplasmic antibody(ANCA) suggested the existence of an ischemic lesion due to vasculitis. Administration of corticosteroids ameliorated the clinical symptoms and MRI findings. Renovascular angiogram revealed the presence of fibromuscular dysplasia(FMD) at the left renal artery but no malformation was found at the cervical arteries. We discussed the possibility of relationships between myelopathy, FMD, IL-8, and ANCA.

Local implantation of autologous bone marrow cells for therapeutic angiogenesis in patients with ischemic heart disease: clinical trial and preliminary results

A new therapy for severe ischemic heart disease has been developed; therapeutic angiogenesis induced by the local implantation of autologous bone marrow cells (BMC). After confirming that no detrimental changes were induced by this treatment in a canine heart model, a clinical trial was commenced in 1999. Thus far, 5 patients have been given this new treatment concomitant with coronary artery bypass grafting and all have been followed up for at least 1 year. Autologous BMC were implanted into the ungraftable area and postoperative cardiac scintigraphy showed specific improvement in coronary perfusion in 3 of the 5 patients. Postoperative chest radiography, electrocardiography, echocardiography and blood tests did not reveal any detrimental changes. In conclusion, this new therapy appears to be safe and could provide a treatment option for patients with otherwise untreatable ischemic heart disease.

[Feasibility of early tapering and discontinuation of cyclosporine to intensify the graft-versus-leukemia effect in patients with advanced hematologic neoplasms]

Twenty patients with advanced hematological malignancies at high risk of relapse who had each received a bone marrow transplant from a matched sibling were registered between October 1996 and January 2000. Cyclosporine (CSP) was tapered on day 40 and stopped on day 50 in 10 patients without prior grade II-IV acute graft-versus-host disease (GVHD), relapse or active infection. These patients were eligible for early tapering of CSP. Although grade II/III acute GVHD was observed in three patients and chronic GVHD in eight patients after CSP tapering, no patients died of GVHD. Three patients died due to disease relapse and one patient died of idiopathic interstitial pneumonia while in remission. The probability of event-free survival at 2 years was 60%. These result indicate that early tapering and withdrawal of CSP is feasible and may provide a graft-versus-leukemia effect in patients with advanced leukemia.

New method of on-line quantification of regional wall motion with automated segmental motion analysis

We have recently developed an automated segmental motion analysis (A-SMA) system, based on an automatic "blood-tissue interface" detection technique, to provide real-time and on-line objective echocardiographic segmental wall motion analysis. To assess the feasibility of A-SMA in detecting regional left ventricular (LV) wall motion abnormalities, we performed 2-dimensional echocardiography with A-SMA in 13 healthy subjects, 22 patients with prior myocardial infarction (MI), and 9 with dilated cardiomyopathy (DCM). Midpapillary parasternal short-axis and apical 2- and 4-chamber views were obtained to clearly trace the blood-tissue interface. The LV cavity was then divided into 6 wedge-shaped segments by A-SMA. The area of each segment was calculated automatically throughout a cardiac cycle, and the area changes of each segment were displayed as bar graphs or time-area curves. The systolic fractional area change (FAC), peak ejection rate (PER), and filling rate (PFR) were also calculated with the use of A-SMA. In the control group, a uniform FAC was observed in real time among 6 segments in the short-axis view (60% +/- 10% to 78% +/- 9%), or among 5 segments in either the 2-chamber (59% +/- 12% to 75% +/- 16%) or 4-chamber view (58% +/- 13% to 72% +/- 12%). The variations of FAC, PER, and PFR were obviously decreased in infarct-related regions in the MI group and were globally decreased in the DCM group. We conclude that A-SMA is an objective and time-saving method for assessing regional wall motion abnormalities in real time. This method is a reliable new tool that provides on-line quantification of regional wall motion.

Ischemic preconditioning attenuates cardiac sympathetic nerve injury via ATP-sensitive potassium channels during myocardial ischemia

BACKGROUND

During myocardial ischemia, massive norepinephrine (NE) is released from the cardiac sympathetic nerve terminals, reflecting the sympathetic nerve injury. A brief preceding ischemia can reduce infarct size; this is known as ischemic preconditioning (PC). The effect of PC on sympathetic nerves, however, including its underlying mechanisms in dog hearts, has remained unclear. Thus, this study was designed to elucidate whether the activation of ATP-sensitive potassium (K(ATP)) channels is involved in the mechanism of cardiac sympathetic nerve protection conferred by PC.

METHODS AND RESULTS

Interstitial NE concentration was measured by the in situ cardiac microdialysis method in 45 anesthetized dogs. Five minutes of ischemia followed by 5 minutes of reperfusion was performed as PC. In the controls, the dialysate NE concentration (dNE) increased 15-fold after the 40-minute ischemia. PC decreased dNE at 40-minute ischemia by 59% (P<0.01), which was reversed by glibenclamide. A K(ATP) channel opener, nicorandil (25 microg. kg(-1). min(-1) IV), decreased dNE at 40 minutes of ischemia by 76% (P<0.01), which was also reversed by glibenclamide. During the PC procedure, no significant increase in dNE was detected, even with the uptake-1 inhibitor desipramine.

CONCLUSIONS

Cardiac sympathetic nerve injury during myocardial ischemia was attenuated by PC via the activation of K(ATP) channels, but the trigger of the PC effect is unlikely to be NE release in dog hearts.

Anthracycline-induced cardiomyopathies evaluated by tissue Doppler tracking system and strain rate imaging

OBJECTIVES

Anthracycline cardiotoxicity is known to occur from the subendocardial side of the left ventricular wall. Recent advances of tissue Doppler echocardiography may allow the evaluation of anthracycline cardiotoxicity by dividing the left ventricular wall into the subendocardial half and subepicardial half. The present study assessed the feasibility using the tissue Doppler echo tracking system (M-mode) and myocardial strain rate imaging (B-mode) to noninvasively detect anthracycline cardiotoxicity.

METHODS

The tissue Doppler echo tracking system (M-mode) was used to measure systolic thickening of the subendocardial layer (delta Endo), subepicardial layer (delta Epi), and whole wall (delta Total) of the left ventricular posterior wall in 41 normal subjects and three groups of patients receiving anthracycline: 34 patients in the low dose group, 19 in the middle dose group, and 12 in the high dose group. Strain rate is the spatial gradient of local velocities, reflecting local compression and expansion rates not affected by overall heart motion. Myocardial strain rate imaging (B-mode) was used in 25 normal subjects, 9 patients in the low dose group, and 10 patients in the high dose group. The ratio of peak systolic strain rate of subendocardium to that of subepicardium (peak strain rate endo/epi), and the ratio of integrated strain rate during ejection time of subendocardium to that of subepicardium (integrated strain rate endo/epi) were measured.

RESULTS

Tissue Doppler echo tracking system (M-mode) measurement of delta Endo/delta Epi showed the most distinct difference and the least overlap of the data between normal subjects and patients, whereas delta Total failed to show significant differences. Myocardial strain rate imaging (B-mode) measurement of integrated strain rate endo/epi showed the most distinct difference and the least overlap of the data between normal subjects and patients, but ejection fraction failed to show statistically significant differences.

CONCLUSIONS

These methods are highly sensitive tools for monitoring anthracycline cardiotoxicity.

Direct closure of ostium primum defect in the repair of atrioventricular septal defect

BACKGROUND

Patch closure is generally performed for atrial septation of an atrioventricular septal defect. We recently developed a new surgical technique for repairing atrioventricular septal defects that avoids the use of any patch material for closing the atrial septal defect. We report our experience with this procedure.

METHODS

Seven patients (complete type: 5, partial type: 2) underwent this new operation. The diameters of the atrial septal defects were measured by transesophageal echocardiography. The preoperative electrocardiograms were compared with those taken after the operations.

RESULTS

Diameters of the atrial defects ranged from 3 to 10 mm. Electrocardiograms before and after the operations did not change. No significant atrioventricular valve regurgitation and no residual shunts were detected by postoperative echocardiography.

CONCLUSIONS

This method simplifies the repair of atrioventricular septal defects. In the short-term results, no arrhythmia and no valve regurgitation was seen.

[Successful second transplant from one-locus HLA-mismatched unrelated donor for graft rejection following initial transplant from another unrelated donor in a patient with chronic myelogenous leukemia]

We report a patient with chronic myelogenous leukemia who received a second transplant from a one-locus HLA-mismatched unrelated donor after rejection of an initial bone marrow graft. For the first transplant, HLAs were fully matched, conditioning with busulfan + cyclophosphamide (CY) was applied, and cyclosporin A + short-term methotrexate (sMTX) was used for prophylaxis against GVHD. A complete chimera was not obtained, and the graft was rejected on day 122. For the second transplant, there was a one-HLA locus (DR) mismatch, conditioning was done with total body irradiation + cytarabine + CY, and GVHD prophylaxis consisted of FK506 + sMTX. Engraftment was obtained on day 27, and no graft failure was occurred at the time of writing. This case suggests that strong immunosuppression may have prevented rejection of the second bone marrow graft.

Bronchiolitis obliterans organizing pneumonia (BOOP) with suspected liver graft-versus-host disease after allogeneic bone marrow transplantation

We report on a patient with chronic myelogenous leukemia who developed bronchiolitis obliterans organizing pneumonia (BOOP) after allogeneic bone marrow transplantation (BMT). A 19-year-old Japanese male complained of dry cough and dyspnea 7 months after BMT. The chest X-ray and computed tomography revealed patchy infiltrates bilaterally. Lung function test, lung biopsy and bronchoalveolar lavage were consistent with the diagnosis of BOOP. The patient also suffered from suspected graft-versus-host disease (GVHD) of the liver, after discontinuation of cyclosporine. Furthermore, prednisolone proved effective against the BOOP and the liver dysfunction. These findings indicate that BOOP is a possible pulmonary manifestation of chronic GVHD, and that immunological mechanisms may have effected the onset of BOOP after BMT in this case.

Glycerol affects vestibular evoked myogenic potentials in Meniere's disease

OBJECTIVES

to show that abnormal vestibular evoked myogenic potentials on the sternocleidomastoid muscle (SCM) in patients with unilateral Meniere's disease are caused by endolymphatic hydrops.

SUBJECTS

six normal volunteers and 17 patients with unilateral Meniere's disease were examined.

METHODS

click-evoked myogenic potentials were recorded with surface electrodes over each SCM. Responses evoked by clicks recorded after oral administration of glycerol (1.3 g/kg body weight) were compared with those recorded before administration.

RESULTS

the change rate of the p13-n23 amplitude was calculated. The mean+standard deviation (S.D.) of the change rate was 3.52+14.6% in normal subjects. On the unaffected side of patients the change rates were within the normal range (within the mean+/-2S.D.) in 13 patients, and three ears showed significant decrease. Only one ear showed significant increase. On the affected side, five ears showed significant increase of the amplitude while two ears showed significant decrease after oral administration of glycerol. Effects on evoked myogenic potentials were independent of those on pure tone hearing.

CONCLUSION

vestibular evoked myogenic potentials in some patients with unilateral Meniere's disease were improved by oral administration of glycerol. This result suggests that abnormal vestibular evoked myogenic potentials in patients with unilateral Meniere's disease could result from endolymphatic hydrops.

Orphan G protein-coupled receptor, GPR41, induces apoptosis via a p53/Bax pathway during ischemic hypoxia and reoxygenation

Orphan receptors that couple to G protein without known ligands are considered to relate directly to drug discovery. Here, we examine the expression of various orphan receptors in H9c2 cells during ischemic hypoxia and reoxygenation. Among orphan receptors examined, the level of G protein-coupled receptor 41 (GPR41) mRNA increases significantly, with a peak at 2 h after reoxygenation, and recovers to the control level by 3 h after reoxygenation. The level of glyceraldehyde-3-phosphate dehydrogenase mRNA used as an internal control remains almost constant. The levels of c-fos and c-jun mRNA increase significantly with ischemic hypoxia and reoxygenation. The transfection of GPR41 into H9c2 cells results in a significant decrease in cell number, with DNA fragmentation observed by in vitro and in situ assay. The amount of p53 protein increases significantly in the nuclei of cells expressing GPR41, accompanying an increase in the transcriptional activity of p53. Consistent with the activation of p53, the level of bax mRNA is significantly increased, which leads to an increase in Bax protein. Furthermore, the expression of a deletion mutant of a GPR41, which lacks the G protein binding site and shows an attenuation of intracellular phosphorylation signals to H9c2 cells, inhibits cell death and the increase in p53 protein within 24 h after reoxygenation. These observations demonstrate that GPR41 is a novel receptor that activates p53 leading to apoptosis during reoxygenation after ischemic hypoxia in H9c2 cells. We have designated GPR41 as the hypoxia-induced apoptosis receptor, HIA-R.

The induction of angiogenesis by the implantation of autologous bone marrow cells: a novel and simple therapeutic method

BACKGROUND

Bone marrow contains many kinds of primitive cells that could differentiate to endothelial cells and secrete several growth factors. In the current study, we attempted to induce therapeutic angiogenesis by implanting autologous bone marrow cells (BMCs) and using a rat ischemic hind limb model.

METHODS

BMCs were prepared by removing red blood cells. A rat ischemic hind limb model was made by the ligation of the left femoral artery and its branches. BMCs were injected into 7 points of the ischemic muscles. To assess angiogenesis, a microangiogram, laser Doppler, and histologic evaluation were performed after the surgical procedure.

RESULTS

A microangiogram and histologic evaluation showed that angiogenesis was significantly induced in the ischemic hind limb by the implantation of BMCs. Laser Doppler imaging analysis showed that blood flow was significantly increased after implantation of BMCs. Some implanted BMCs were stained positively with CD31 and vascular endothelial-cadherin (VE-cadherin), which might have been incorporated into the vasculature. The condition of ischemia caused an elevation in the level of basic fibroblast growth factor in the ischemic muscle and also in interleukin-1beta derived from the implanted BMCs, which might contribute to angiogenesis.

CONCLUSION

These findings indicate that autologous bone marrow implantation may be a novel and simple method for inducing therapeutic angiogenesis.

Appropriate dosing of pilsicainide hydrochloride in patients on hemodialysis

Appropriate dosing of pilsicainide hydrochloride, an anti-arrhythmic drug excreted via the kidney, was investigated in patients on dialysis. Ten chronic hemodialysis patients with coexisting severe palpitation of supraventricular premature contractions (SVPC) were treated with 25 mg of pilsicainide hydrochloride before dialysis. All of their plasma concentrations were maintained within the therapeutic range and their mean dialysis rate was 32%. After 2 weeks, 7 patients were followed with consecutive daily dose treatment. In 3 of them, the dosage was returned to the single pre-dialysis administration because of the elevated plasma concentration reaching the toxic range 1 month after the start of administration. The dose schedule was maintained, and plasma pilsicainide concentrations remained within the therapeutic range during the 6-month follow-up. No abnormal findings were found in any parameters of electrocardiography, echocardiography or biochemistry. The number of SVPC diminished > 90% compared to the pretreatment level.

Immune reconstitution assessed during five years after allogeneic bone marrow transplantation

Immune reconstitution is an important component of successful allogeneic bone marrow transplantation. Immune reconstitution was evaluated for 5 years after transplantation. While the number of CD8+ T cells and CD56+ cells recovered early post transplantation, a low number of CD4+ and CD4+ CD45RA+ T cells and reversal of the CD4/CD8 ratio continued up to 5 years. Although early recovery of IgG and IgM was seen at day 100 post transplantation, serum concentration of IgA was below the normal range at 6 months and increased gradually up to 5 years. Development of acute GVHD did not affect the numbers of CD4+, CD8+, CD4+ CD45RA+ and CD4+ CD29+ T cells, but the number of CD56+ cells in patients who developed grades II-IV acute GVHD was low. The number of CD4+ CD29+ T cells had a tendency to be higher in the patients with extensive chronic GVHD than in those without chronic GVHD 2 years after transplantation whereas the number of CD4+ CD45RA+ T cells was low in spite of the absence of chronic GVHD. Serum concentration of IgA was lower in patients with extensive chronic GVHD than in those without chronic GVHD at 180 days. The number of CD4+ CD45RA+ cells in 10-19-year-old patients was higher than that in 40-49-year-old patients. Response to the Con A and PHA in 10-19-year-old patients was higher than that in older patients at 1 and 2 years. There was no significant difference in the ability of immune reconstitution between related transplant recipients and unrelated transplant recipients. These results suggest that chronic GVHD and age of patients affected immune reconstitution post transplant.

[RyR-bound FKBP12.6 and the modulation]

In the pathogenesis of cardiac dysfunction in heart failure, a decrease in the activity of the sarcoplasmic reticulum (SR) Ca(2+) -ATPase is believed to be a major determinant. Recently, a novel mechanism of cardiac dysfunction in heart failure has been reported on the basis of the following findings:1) PKA hyperphosphorylation of RyR causes a dissociation of FKBP12.6 from RyR, resulting in the abnormal single-channel properties (increased Ca(2+) sensitivity for activation and elevated channel activity associated with destabilization of RyR (Marx et al, Cell 101:365, 2000), 2) a prominent abnormal Ca(2+) leak occurs through RyR, following a partial loss of RyR-bound FKBP12.6 and the resultant conformational change in RyR (Yano M et al, Circulation 102:2131, 2000). This abnormal Ca(2+) leak might possibly cause Ca(2+) overload and consequent diastolic dysfunction, as well as systolic dysfunction.

[Accuracy and usefulness of ultraportable hand-carried echocardiography system]

OBJECTIVES

The diagnostic accuracy and usefulness of an ultraportable hand-carried echocardiography system were investigated for assessing ventricular systolic function and severity of mitral valvular regurgitation.

METHODS

The study population consisted of 77 consecutive patients (47 men, 30 women, mean age 63 +/- 15 years). Left ventricular end-diastolic dimension, left ventricular end-systolic dimension and left ventricular ejection fraction were measured using the hand-carried echo system and the data were compared with measurements by the conventional echocardiography system using simple linear regression analysis. Left ventricular wall motion was compared between the systems using a 16-segment model recommended by the American Society of Echocardiography. Severity of mitral regurgitation was assessed by the distance of the regurgitant signal in the left atrium.

RESULTS

Left ventricular end-diastolic dimension, left ventricular end-systolic dimension and left ventricular ejection fraction showed good correlations between hand-carried and conventional echo systems (r = 0.94, 0.91 and 0.81, respectively; each p < 0.0001). The accuracy for assessing left ventricular wall motion was 94% (449 of 480 segments). The echo systems also showed the same degree of diagnostic accuracy for severity of mitral regurgitation.

CONCLUSIONS

The hand-carried echo system provides accurate assessment of left ventricular function and mitral regurgitation simular to conventional echo machines.

Effects of cardioplegic arrest and reperfusion on rabbit cardiac ryanodine receptors

Calcium overload is considered to be a primary contributor to ischemia-reperfusion injury. Cardiac sarcoplasmic reticulum (SR), the main regulator of intracellular Ca2+ concentration under normal conditions, is a target for ischemic myocardial injury. The ryanodine receptor (RyR) is the SR Ca2+ release channel. Previous reports have shown that a reduction in RyR activity during global myocardial ischemia correlates with concomitant myocardial dysfunction. Crystalloid cardioplegia, a technique for myocardial protection during heart operations, reduces Ca2+ accumulation during global ischemia. Hence, the effects of cardioplegia on RyR in isolated rabbit hearts was investigated. The study also compared [3H] ryanodine binding before ischemia (control group), after 30 min of ischemia (either global ischemia (GI group) or cardioplegic arrest (CA group)), and after 20 min of reperfusion. The GI group, but not the CA group, showed a significant reduction in the maximum number of binding sites (Bmax) for RyR compared with the control group (Control vs GI group: after ischemia, 1.33+/-0.27 vs 0.83+/-0.12 pmol/mg protein, p<0.05; after reperfusion, 1.33+/-0.27 vs 0.80+/-0.08 pmol/mg protein; p<0.05). CA group: after ischemia, 1.22+/-0.20 pmol/mg protein; after reperfusion, 1.15+/-0.28 pmol/mg protein). The affinity (Kd) values for [3H] ryanodine binding were not different among the 3 groups at any point. The preservation of RyR numbers during cardioplegia correlated with the concomitant preservation of cardiac functions. The results indicate that number of functional RyR was much better preserved during cardioplegia than during global ischemia. It is postulated that cardioplegia-induced protection of cardiac RyR may result in the protection of SR function during ischemia-reperfusion.