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Biomedical subjects

S Kyo

Publications and source records attributed to S Kyo.

At least 163 records · Page 9Linked to original sources
PubMed1987

Myocardial temperature variation: effect on regional function and coronary flow in dogs.

Incremental changes in the temperature (28-42.5 degrees C) of the anterior left ventricular wall in a canine, working, beating right heart bypass preparation (constant preload, afterload, and heart rate) were produced to measure the effect of regional temperature on myocardial function and blood flow. Circumferential-axis segment lengths were measured with sonomicrometry in both the temperature-varied, left-anterior descending coronary artery (LAD)-supplied myocardium and the normothermic (38 degrees C) circumflex-supplied myocardium. Fast thermistors (time constant less than 0.25 s) continuously monitored midmyocardial temperature in both areas. A Silastic loop with heat exchanger, thermistors, strain gauge, and flow probe was inserted into the LAD and allowed precise control of regional myocardial temperature. Nine-micron microspheres injected into left atrium were used to evaluate coronary flow and distribution. In six anesthetized dogs, relative to normothermic control (38 degrees C), regional systolic shortening decreased 42.2 +/- 10% at 41 degrees C and increased 23.3 +/- 6% at 31 degrees C. There was no significant change in coronary blood flow or distribution at the three temperatures. Pressure-length areas varied inversely with myocardial temperature. These data demonstrate that there is a reversible inverse relationship between midwall T and ventricular function when heart rate, preload, and after-load are controlled.

Animals↗
PubMed1987

[Color flow mapping 2-D Doppler in determining surgical indication for congenital heart disease].

Real-time two-dimensional Doppler echocardiography (2-D Doppler) is established as an effective diagnostic tool for cardiovascular diseases. However, in determining indications for surgery of congenital heart disease (CHD), the possibility of avoiding preoperative cardiac catheterization including radiographic angiography, has not been fully discussed since the clinical introduction of 2-D Doppler. We evaluated 278 patients with CHD by 2-D Doppler including ASDs (75 patients), VSD (76 patients), TOF (23 patients), TGA (12 patients), PDA (23 patients), ECD (13 patients), and 60 miscellaneous types of CHD during 27 months. The diagnosis of the 278 patients were confirmed by catheterization and/or surgery. Of these, 114 patients underwent corrective surgery (83 patients) or palliative procedures (31 patients). Preoperative cardiac catheterization was performed for 88 patients (Group A), and omitted in 26 patients (Group B). The 2-D Doppler diagnosis was correct in 79 patients of Group A (89.8%) and in 26 patients of Group B (100%). The surgical procedures scheduled according to the preoperative 2-D Doppler diagnosis were performed for these 105 patients (92.7%) without any corrections by cardiac catheterization diagnosis or by surgical findings. However, 2-D Doppler failed to establish the preoperative diagnosis for six patients in Group A (two patients with ASD, three with PDA, and one with TOF) and failed to detect associated cardiac abnormalities for three patients in Group A (two with PAPVC, one with Azygos connection). Results of this study suggest that preoperative cardiac catheterization could be omitted in a maximum of about 90% of surgical candidates with CHD. However, to omit cardiac catheterization 2-D Doppler echocardiographic criteria for indications for surgery in each group of CHD must be established, and any associated coronary artery abnormalities must be ruled out.

Adult↗
PubMed1987

Immediate and early postoperative evaluation of results of cardiac surgery by transesophageal two-dimensional Doppler echocardiography.

In cardiac surgery significant residual lesions increase postoperative morbidity and mortality. Although intraoperative epicardial real-time two-dimensional Doppler echocardiography (two-dimensional Doppler) is an accurate and efficient technique for assessing the presence and severity of a residual lesion, it requires placement of a transducer in the operating field and consequent obstruction of the operative procedure. Transesophageal two-dimensional Doppler echocardiography (transesophageal two-dimensional Doppler), which can be applied intraoperatively and postoperatively without such problems, was performed in 35 patients during cardiac surgery (12 patients) and/or at an intensive care unit within 6 hr after cardiac surgery (30 patients). In those with constrictive pericarditis, an extensive pericardiectomy was performed with effective monitoring by intraoperative transesophageal two-dimensional Doppler. Abnormal posterior wall motion was observed in the case of left ventricular rupture (type III) after mitral valve replacement 3 hr before clinical manifestation. After prosthetic valve replacement (18 St. Jude Medical valves, one Carpentier-Edwards valve, one Björk-Shiley valve), no perivalvular leakage was detected, but minor physiologic transvalvular leakage was noticed in 11 patients with St. Jude Medical valves. In two patients with congenital heart disease, a small residual shunt was detected. In a patient in which a composite valve graft with direct coronary artery reattachment (Bentall's operation) was performed, reattachment was confirmed to be satisfactory. In conclusion, intraoperative and early postoperative monitoring of cardiac function by transesophageal two-dimensional Doppler echocardiography can improve the results of cardiovascular surgery by providing accurate information on cardiovascular structure and blood flow dynamics.

Adult↗
PubMed1986

Doppler ultrasound examination of prosthetic function and ventricular blood flow after mitral valve replacement.

Two-dimensional color Doppler echocardiography enables delineation of the spatial and temporal distribution of blood flow in the heart. In this study, the method was applied for investigation of flow dynamics in multiple planes in the region of prosthetic mitral valves for comparison with that of native mitral valves. In 15 healthy subjects there was normal flow toward the transducer, coded in red, in the left ventricle along the posterolateral wall (left ventricular inflow region) and blue-coded flow away from the transducer in the left ventricular outflow region during diastole. In 40 patients with St. Jude mitral valve prosthesis and 17 with bioprosthesis the flow pattern in the left ventricle was reversed. Mitral inflow was directed against the interventricular septum, accordingly, into the left ventricular outflow region while the outflow pattern was displaced posterolaterally into the left ventricular inflow region during diastole. The angle between the aortic valve ring and the mitral annulus was significantly smaller than in the healthy subjects. The angle between the central axis of the mitral prosthesis and the mitral inflow, which was 0 degrees in healthy subjects, was increased by the medial deviation in particular, in those with mechanical St. Jude prostheses. The maximal transprosthetic velocity, measured in 70 patients, and the maximal pressure gradient calculated according to the Bernoulli equation was substantially greater than the values in healthy subjects. In contrast to findings associated with normally-functioning prostheses, in four patients with prosthetic malfunction there was a diastolic peak velocity of more than 2 m/s as well as marked turbulence in the inflow region.

Bioprosthesis↗
PubMed1986

[Immediate surgical revascularization following unsuccessful coronary thrombolysis: effects on myocardial salvage].

To reduce early and late mortality and morbidity following acute myocardial infarction (AMI), myocardial salvage of the jeopardized areas by coronary thrombolysis (PTCR) during the acute period is effective. However, unsuccessful thrombolysis or severe residual coronary stenosis may result in severe cardiac failure and high mortality in the early and late periods. This study was undertaken to demonstrate the effects of immediate coronary artery bypass surgery (CAB) following unsuccessful PTCR. Thirty-three patients with initial AMI were studied, in whom PTCR was performed within 10 hours of onset of chest pain but it was unsuccessful. In 16 cases (Group I) total occlusion could not be recanalized, and in 17 cases (Group II) subtotal residual stenosis (99% with delayed flow on coronary angiogram) remained. The effects of immediate CAB surgery (Group I-b: 4 cases; Group II-b: 9 cases) for myocardial salvage were evaluated by thallium-201 scintigraphy one to 14 months after onset of AMI, as compared to medical therapy (Group I-a: 12 cases; Group II-a: 8 cases). The thallium uptake in the jeopardized area was categorized as (1) defect (+), (2) decrease, and (3) defect (-). All 12 cases in Group I-a showed defect (+). In Group I-b, one case showed defect (+), one case decreased, and two cases defect (-). In Group II-a, seven of eight cases (88%) showed defect (+) and one case showed decrease; however, in Group II-b seven of nine cases (78%) showed defect (-) and two cases showed defect (+). The effects on myocardial salvage were significantly different between Group a and Group b (p less than 0.001) and Group II-a and Group II-b (p less than 0.01). In conclusion, immediate CAB surgery was superior to medical therapy for ischemic myocardial salvage following unsuccessful PTCR. These results encourage the application of immediate postinfarction CAB surgery in high-risk groups with severe residual coronary stenosis after PTCR.

Aged↗
PubMed1986

[Visualization of coronary blood flow by transesophageal Doppler color flow mapping].

For noninvasive evaluation of coronary blood flow, 22 patients were examined with transesophageal Doppler color flow mapping within six hours after cardiovascular surgery. The anatomical structure of the left main coronary trunk (LMT) was observed by conventional two-dimensional echocardiography (2-DE) in 20 patients (91%), and color flow of the LMT was visualized in 18 of 21 patients (86%) (one patient had total occlusion). The blood flow in the LMT began in mid-systole, but the flow was observed mainly in diastole. The peak of the flow was observed mainly in late diastole and the range of the peak velocity was 35 to 163 cm/sec (average = 76.9 +/- 31.4 cm/sec). The proximal portion of the right coronary artery (RCA) was observed in 13 patients (59%), and its color flow was visualized in only two patients (9%). In two patients intra-aortic balloon pumping (IABP) assist was performed postoperatively, and the direct effect of the assist on the coronary blood flow was clearly observed by transesophageal Doppler color flow mapping. The peak blood flow velocity of the LMT increased by 32% during the assist. In conclusion, human coronary blood flow can be visualized and evaluated noninvasively using transesophageal Doppler color flow mapping. This technique can be used for future investigation of coronary circulation.

Adult↗
PubMed1985

Intraoperative color flow mapping by real-time two-dimensional Doppler echocardiography for evaluation of valvular and congenital heart disease and vascular disease.

We have developed real-time two-dimensional Doppler echocardiography, which can display color flow mapping on a two-dimensional echocardiogram. Intraoperative two-dimensional Doppler echocardiography was performed during cardiovascular operations before and after the definitive procedure in 33 patients, 14 with valvular disease, eight with congenital heart disease, and 11 with vascular disease. Its clinical usefulness was evaluated. In patients with valvular heart disease, 13 valve replacements, 10 valvuloplasties, and four untouched lesions were assessed. No paravalvular leakage and three instances of minimal physiological transvalvular leakage from St. Jude Medical valves in the mitral position were noticed. Regurgitation after valvuloplasty was graded by extent of the regurgitant flow. This grading, comparable to postoperative grading, indicated no need for an additional procedure. In congenital heart disease, preoperative diagnoses were confirmed. The effect of the corrective operation was evaluated and no significant leakage or stenosis was found. Interatrial shunt flow was shown to increase after operative balloon atrial septostomy in a patient with dextro-transposition of the great arteries. In 11 patients with dissecting aortic aneurysm, the aneurysm was totally visualized in the operative field, including the structure and flow dynamics. In two patients, the preoperative cineangiographic diagnosis regarding involvement of dissection was corrected. After the vascular procedure, sufficient flow in the major aortic branches was confirmed in all patients and minimal leakage at the suture line was noticed in four patients. In conclusion, intraoperative color flow mapping by two-dimensional Doppler echocardiography has enabled the precise diagnosis and the necessary operation to be determined before cardiopulmonary bypass. It has also allowed the effects of the operation to be assessed before chest closure.

Adult↗
PubMed1984

Dynamic patch artificial myocardium; effects on the residual myocardial function.

Dynamic patch artificial myocardium (D-PATCH) has been developed to replace the damaged left ventricular (LV) wall in severe cardiogenic shock patients with a massive myocardial infarction. This study was undertaken to demonstrate the effects of (1) single D-PATCH support on the global cardiac function (group 1, 12 dogs, whole heart model), (2) single D-PATCH support on the LV function and myocardial metabolism (group 2, 6 dogs, right heart bypass model), and (3) the concomitant support of D-PATCH and aortic counterpulsation (CP) on the regional myocardial function of the residual LV wall (group 3, 6 dogs, right heart bypass model with ultrasonic piezoelectric crystals). In group 1, mean aortic pressure and cardiac output were increased 20-36% (p less than 0.01) and 17-50% (p less than 0.01) respectively, and mean left atrial pressure was decreased 16% (p less than 0.01) by D-PATCH assist. In group 2, under constant preload volume, afterload pressure and heart rate, tension time index (TTI) was decreased 21-26% (p less than 0.01) and myocardial oxygen consumption was also decreased 24-29% (p less than 0.001) by D-PATCH assist. In group 3, although peak LVP was increased by single D-PATCH assist, when heart was assisted concomitantly by D-PATCH and CP peak LVP was significantly decreased (18%, p less than 0.01). Percent LV segmental shortening was not increased by CP assist, but increased 143% (p less than 0.02) by D-PATCH assist. In conclusion, D-PATCH can improve the global LV function and myocardial metabolism of the ischemic failing heart, also improve the regional myocardial function of the residual LV wall. Thus, D-PATCH is effective for the salvage of ischemic myocardium while maintaining the global cardiac function.

Animals↗
PubMed1984

The development of real-time two-dimensional Doppler echocardiography and its clinical significance in acquired valvular diseases. With special reference to the evaluation of valvular regurgitation.

A noninvasive method for real time blood-flow imaging using ultrasound has long been required in the fields of cardiology and cardiovascular surgery. Recently, we developed a method of two-dimensional Doppler echocardiography (hereafter abbreviated as "2-D Doppler") for clinical use which allows us to obtain noninvasively, intracardiac blood-flow images in real time. The main purpose of this paper is to describe the newly developed blood-flow imaging system "2-D Doppler" and to demonstrate its clinical usefulness in acquired valvular diseases, particularly in the evaluation of valvular regurgitation. The device, in principle, combines a conventional pulsed-Doppler system and a newly developed auto-correlator, in which blood-flow images within a given cross section of a beating heart are noninvasively displayed in real time, simultaneously with conventional two-dimensional echocardiograms. The system can provide three kinds of information, direction, velocity and turbulence of blood flow. The 2-D Doppler examinations were carried out on 72 patients with acquired valvular diseases whose diagnoses were confirmed by angiography and/or surgery. Studies were performed comparing the findings of the 2-D Doppler and those of angiography (for aortic and mitral lesions) or with operative findings (for tricuspid lesions) in the quantitative evaluation of valvular regurgitation. Aortic, mitral and tricuspid valvular regurgitation have been quantitatively demonstrated with 2-D Doppler, and, for each value, the severity of the regurgitation showed a high correlation between the findings of 2-D Doppler and of angiography or surgery. In conclusion, we have found that (1) 2-D Doppler is very useful in detecting and estimating the severity of valvular regurgitation, and that (2) 2-D Doppler may replace conventional angiography in some situations.

Aortic Valve Insufficiency↗
PubMed1984

[Real-time two-dimensional Doppler echocardiography in congenital heart disease: its clinical significance].

This study demonstrated the diagnostic usefulness of the newly-developed real-time two-dimensional Doppler echocardiography (2-D Doppler) in congenital heart disease. Among fifty-four patients with congenital heart disease, 18 had ASD; 16, VSD; 6, T/F; 3, PDA; 3, d-TGA; 3, ECD; and 1 each, DORV, PA, PS, Ebstein's anomaly, and ruptured aneurysm of the sinus of Valsalva. Each diagnosis was confirmed by cardiac catheterization and/or surgery. Forty normal cases were subjected as the control. The study cases included 26 adults and 28 children under 15 years old, 13 infants and seven newborns. In 52 cases (96.3%) 2-D Doppler provided diagnostic abnormal intracardiac blood flow images which were compatible with the data of cardiac catheterization and cardiac angiography and/or patients' cardiac anatomy observed during surgery. The blood flow data obtained by 2-D Doppler facilitated determining the appropriate timing of palliative surgery such as the Blalock-Taussig shunt procedure. 2-D Doppler was effective in evaluating medical (pharmaco-echocardiography) and surgical therapy including radical and palliative procedures for congenital heart disease. Thus, 2-D Doppler proved a non-invasive and useful diagnostic method for congenital heart heart disease. Our data suggest that with this technique cardiac surgery can be performed without cardiac catheterization or cardiac angiography in some cases of congenital heart disease.

Adult↗
PubMed1983

Myocardial protection by lidocaine during cardioplegia.

This study was undertaken to examine the effects of lidocaine (L) (400 mg/liter) in a normokalemic crystalloid (S) (K +: 5 meq/liter, Na+: 120 meq/liter) and in a hyperkalemic crystalloid cardioplegic solution (K) (K+: 25 meq/liter, Na+: 120 meq/liter) during 90 min of hypothermic (28 degrees C) aortic occlusion followed by 45 min of reperfusion (R). Four groups of dogs were studied: group 1 (S), n = 6; group 2 (S + L), n = 6; group 3 (K), n = 6; group 4 (K + L), n = 6. Left ventricular (LV) function was defined as percentage changes in center of mass between pre- and postarrest function curves. Regional myocardial flow was measured with 9 mu radioactive microspheres and myocardial metabolism monitored by lactate and oxygen utilization. Ventricular biopsies were obtained for measurement of myocardial ATP, creatine phosphate, and water content. Percent recovery of LV function curves at the end of (R) was 59.2 +/- 3.9% in group 1, 85.0 +/- 4.3% in group 2, 71.5 +/- 4.9% in group 3, and 87.0 +/- 4.5 in group 4 (group 1 vs group 2, P less than 0.01; group 3 vs group 4, P less than 0.05). Metabolic recovery was evaluated at 5, 20, and 45 min of (R). Only group 3 (K) demonstrated persistent lactate production at 5 min of (R) (P less than 0.01). The hyperkalemic groups failed to return to control levels of oxygen utilization after 5 min of (R) (group 3, P less than 0.05; group 4, P less than 0.05). LV endocardial/epicardial myocardial blood flow ratio demonstrated greater increase in hyperkalemic groups (group 3, P less than 0.01; group 4, P less than 0.01) at 5 min of (R). ATP was significantly decreased in groups 1, 3 and 4, but not in group 2 at the end of ischemia (group 1, P less than 0.01; group 3, P less than 0.01; group 4, P less than 0.05) and after 45 min of (R) (group 1, P less than 0.05; group 3, P less than 0.01; group 4, P less than 0.01). These results demonstrate that lidocaine has a myocardial protective effect which is superior to standard hyperkalemic cardioplegia. Moreover, lidocaine has an additive salutary effect during potassium cardioplegia. Persistent metabolic derangements post reflow in the hyperkalemic groups suggest deleterious effects of hyperkalemia on subendocardial protection.

Animals↗