No abstract available.
Myocardium*

No abstract available.
Myocardium

Hypertrophic cardiomyopathy is characterized by inappropriate hypertrophy of the myocardium and is associated with various clinical presentations ranging from complete absence of symptoms to sudden, unexpected death. These are caused by dynamic obstruction of the left ventricular outflow tract and surgical approaches were initiated. But, the complete resection of hypertrophied midventricular septum is impossible by standard, transaortic approach, because of narrow vision and limited approach. And it leads to inadequate excision, will leave residual left vetnricular outflow tract obstruction or systolic anterior motion of mitral leaflet, and limit symptomatic improvement and patient's survival. We report a case of extended septal myectomy for hypertrophic cardiomyopathy of mid-septum in a child. The extended septal myectomy was performed by aortotomy and left ventricular apical incision, and made possible the complete resection of mid-ventricular septum, abnormal papillary muscles and chordae. The patient's symptom was improved and the postoperative course was uneventful.
Cardiomyopathy, Hypertrophic* ; Child ; Heart Septum ; Humans ; Hypertrophy ; Myocardium ; Papillary Muscles

The influences of osmolarity on the cardiac muscle contraction were investigated in cat papillary muscles. The muscle was immersed in the modified Krebs-Ringer-bicarbonate solutions containing various Ca ion concentrations and osmolarities and the resultant changes in maximum developed tension, rate of development of tension and time to maximum tension were analyzed. Following are the results. 1) Mean length of papillary muscle used was 9.3+/-0.60mm, end mean cross-sectional area was l. 73+/-0.07 mm2. Normal contraction amplitude at 5 mM Ca ion-K-R-B solution was 2. 46+/-0. 1 gram/mm. 2) Within the range of 2.5-10.0 mM Ca ion concentration, the contraction amplitude increased along with the increment of Ca concentration. 3) Osmolarity exerted dual effects on contraction; within the range of 300-400 mosm/I solution, the hypertonic solution exported a positive inotropic effect while 500 mOsm/1 solution exerted a negative inotropic effect upon papillary muscle. 4) Maximum rate of tension development increased in 350 mOsm/1 solution, but decreased in 400 mOsm/1 or more hypertonic solution. The time to maximum tension did not change within the range of 300 400 mOsm/1 osmolarity and in 500 mOsm/1 solution. 5) The difference in maxium developed tension between single and paired stimulation was 1. 99 gram/mm' at 300 mOsm/1 solution and was negligible in 450 mOsm/1 or more hypertonic solutions.
Animals ; Cats ; Hypertonic Solutions ; Myocardium ; Osmolar Concentration ; Papillary Muscles

BACKGROUND: The synthetic narcotic sufentanil has been used in clinical practice for anesthetic induction and maintenance. But there is little information concerning its direct effects on heart. The purpose of this study is to evaluate the direct effects of sufentanil on contracture of ventricular myocardium. METHODS: Isometric contraction of isolated right ventricular papillary muscle of rabbit was measured under 0.2 Hz electrical stimulation in Krebs solution. Peak developed force(F), maximum rate of rise of developed force(+dF/dt(max)), maximum rate of fall of developed force(-dF/dt(max)) were analyzed. RESULTS: There were no statistically significant differences in frequency of isometric contraction from the 100% baseline value in time-matched control group. Sufentanil, in concentration of 0.01-0.1 mM, increased F, and -dF/dt(max) was decreased especially in concentration of 0.1 mM but not +dF/dt(max) Fo +dF/dt(max) and -dF/dt(max) were statistically different from time-matched control group in concentration of 0.1 mM. CONCLUSIONS: We conclude that sufentanil has mild contracture effect on ventricular muscle of rabbit directly.
Analgesics ; Contracture ; Electric Stimulation ; Heart ; Isometric Contraction ; Myocardium ; Papillary Muscles ; Rabbits* ; Sufentanil*

BACKGROUND: The effects of various concentration (20, 50, 100? M) of mepivacaine were studied in isolated guinea pig and rat right ventricular papillary muscles by measuring the effects on myocardial contractility and electrophysiological parameters. METHODS: Isometric force of isolated guinea pig ventricular papillary muscle was studied in modified normal and 26 mM K+ Tyrode's solution. Rat papillary muscle was used to evaluate the effect on Ca2+ release from the sarcoplasmic reticulum (SR) at low stimulation rates. Normal and slow action potentials (APs) were evaluated by using conventional microelectrode technique. Rapid cooling contractures (RCCs), an index of SR Ca2+ content, which are known to be activated by Ca2+ released from the SR were performed. RESULTS: Mepivacaine caused dose-dependent depression of peak force from 0.5 to 3 Hz stimulation rates in guinea pig papillary muscles. Conduction block was frequently noted especially at higher stimulation rates (2 and 3 Hz) at all concentration ranges. In rat, ~20% depression of peak force was shown at rested state contraction. Shortening of AP duration and rate-dependent depression of dV/dt max could be observed at 100 M mepivacaine. In 26 mM K+ Tyrode's solution, 50 and 100 M mepivacaine caused dose-dependent depression of early and late force development. In slow APs, neither shortening of AP duration nor changes of dV/dtmax were not shown at 100 M mepivacaine. ~30% depression of RCC after 2 Hz stimulation rate was shown at 100 M mepivacaine. CONCLUSION: It may be concluded that the direct myocardial depressant effects of mepivacaine may partly be related to inhibition of Ca2+ release from the SR. Shortening of AP duration in normal APs seems to be partly related by blockade of TTX-sensitive ""window"" Na+ current.
Action Potentials ; Anesthetics ; Animals ; Contracture ; Depression* ; Guinea Pigs ; Mepivacaine* ; Microelectrodes ; Myocardium* ; Papillary Muscles ; Rats ; Sarcoplasmic Reticulum

BACKGROUND: The effects of various concentration (20, 50, 100 micrometer) of meperidine were studied in isolated guinea pig and rat ventricular papillary muscles. METHODS: Isometric force of guinea pig ventricular papillary muscle was examined in normal and 26 mM K+ Tyrode's solution. Experiments using rat and guinea pig papillary muscle under normal and low Na+ (40 mM), respectively, were performed to evaluate the effect on Ca2+ release from the sarcoplasmic reticulum (SR). Normal and slow action potentials (APs) were evaluated by using conventional microelectrode technique. Rapid cooling contractures were performed. RESULTS: Meperidine caused dose-dependent depression of peak force from rested-state (RS) to 3 Hz stimulation rates in guinea pig papillary muscles. Conduction block was frequently noted at high stimulation rates (2 and 3 Hz) at 150 micrometer meperidine. ~40% depression of peak force was shown at RS contraction under low Na+ Tyrode's solution, although contractile depression was not shown at RS and low stimulation rates in rat papillary muscles. 100 micrometer naloxone did not reverse the contractile depression caused by 100 micrometer meperidine. Either depression of dV/dt-max from 0.1 to 3 Hz stimulation rates or rate-dependent depression among 1, 2 and 3 Hz could be observed at 150 micrometer meperidine. In 26 mM K+ Tyrode's solution, 50 and 100 micrometer meperidine caused dose-dependent depression of early and late force development. In slow APs, changes of dV/dt-max were not shown at 100 micrometer meperidine. ~40% depression of contracture induced by rapid cooling following 2 Hz stimulation rates was shown at 100 micrometer meperidine. CONCLUSION: The direct myocardial depressant effect of meperidine seems likely to be caused by local anesthetic properties of meperidine, not by the opioid action. Inhibition of SR Ca2+ release, and decreased intracellular Ca2+ secondary to Na+ channel blocking action of meperidine may at least in part be related to direct myocardial depression.
Action Potentials ; Anesthetics* ; Animals ; Contracture ; Depression* ; Guinea Pigs ; Meperidine* ; Microelectrodes ; Myocardium* ; Naloxone ; Papillary Muscles ; Rats ; Sarcoplasmic Reticulum

BACKGROUND: Cold blood cardioplegic solution has been used to protect myocardium during open heart surgery with the hypothesis stating that it provides more oxygen supply to myocardium compared to crystalloid caridoplegic solution. We repeatedly infused cold blood cardioplegic solution to achieve myocardial protection. We biopsied a small portion of papillary muscle of patients with mitral valve replacement or double valve replacement during aortic cross-clamp time and evaluated the method of myocardial protection through the observation of changes in ultrastructure. We then analysed the relationship between changes in ultrasructure and peak postoperative CK-MB value and SGOT value. MATERIAL AND METHOD: We report observation on changes of myocardial ultrastructure, postoperative CK-MB and SGOT, and electrocardiogram in 31 patients who underwent cardiac operation. There were 11 males and 20 females, and they ranging in age from 28 to 69 years (mean score was 2.08+/-0.560, it was 2.37+/-0.558 at 40 minutes, and it was 2.36+/-0.523 at 70minutes. Mitochondrial score increased significant at 40 minutes. Mean value of postoperative peak CK-MB and SGOT were 37.3+/-17.061IU, 144.5+/-125.5IU respectively. We were not able to find any new Q were in EKG after the operation. There was no significant relationship between myocardium mitochondrial score and mean value of postoperative peak CK-MB and SGOT. CONCLUSION: In conclusion, with this study the cold blood cardioplegic solution was incomplete in preserving ultrastructure of myocardium even with satisfactory results in serum enzyme and EKG evaluation.
Aspartate Aminotransferases ; Cardioplegic Solutions ; Electrocardiography ; Female ; Heart* ; Humans ; Male ; Mitral Valve ; Myocardium ; Oxygen ; Papillary Muscles ; Thoracic Surgery*

BACKGROUND: Low dose dobutamine echocardiography has recently been introduced for use in identification of viable myocardium in patients with acute myocardial infarction and prediction of the response of dysfunctioning myocardial segments to coronary angioplasty. The aim of this study was to evaluate wheter tihs test could be used to predict the early response of dysfunctioning myocardial segements to coronary artery bypass grafting(CABG). METHODS: We studied in 23 patients with multi-vessel disease during CABG. Myocardial segments were monitored by intraoperative transesophageal echocardiography(TEE) in the transgastric short-axis view at papillary muscle level. The left ventricle was divided into five segments and sixty eight myocardial segments in 23 patients were analyzed. Percentage of systolic wall thickening(PSWT) was calculated in each segment for three times: at basline(early after pericardiectomy);before bypass during dobutamine infusion(3-5ug/kg/min);and after seperation from cardiopulmonary bypass. Segments showing baseline PSWT >_30% were considered normal and those < 30% were dysfunctional. Segments showing an increase in PSWT >_10% during dobutamine infusion were considered responders and those < 10% nonresponders. RESULTS: AT baseline, 24%(36%) of 68 segments had PSWT > 30%(normal) and 44(68%) had PSWT < 30%(dysfuctioning segments). During dobutamine infusion, 21(47.7%) among 44 dysfunctional segments showed increase in PSWT >_10%(from 12.3+/-7.2% to 33.5+/-11.8%, p<0.01 ; responder segments), and 23(52.3%) showed increase in PSWT < 10%(from 14.7+/-6.5% to 17.4+/-7.4%, p=NS ; nonresponder segments). After CABG, responder segments showed a significant increase in PSWT in comparison with baseline values(from 12.3+/-7.2% to 32.1 +/-11.0%,p<0.01). Segments not responded to dobutamine showed no significant changes in PSWT after CABG(from 14.7+/-6.5% to 16.0+/-8.2%, p=NS). Twenty-four normal segments (PSWT 41.9+/-6.2%) showed a slight but significant reduction in PSWT both during dobutamine infusion(38.7+/-6.9%;p<0.05) and after CABG(38.9+/-6.3%, p<0.05), suggesting that compensatory hyperfunction was present at baseline. Estimation of clinical accruacy of low dose dobutamine TEE yieded to 69% sensitivity, 93.9% specificity, 95.2% positive predictive value, 60.9% negavive predictive value, and 77.3% overall accuracy. In both responders and nonresponders of dysfunctioning segments, there was a correlation between PSWT during dobutamine infusion and that after CABG(r=0.61, r=0.63, respectively). CONCLUSION: Low dose dobutamine TEE test well predicts the early response of dysfunctioning myocardial segments to CABG.
Angioplasty ; Cardiopulmonary Bypass ; Coronary Artery Bypass* ; Coronary Vessels* ; Dobutamine* ; Echocardiography* ; Heart Ventricles ; Humans ; Myocardial Infarction ; Myocardium ; Papillary Muscles ; Sensitivity and Specificity

In the mitral regurgitation (MR) accompanied with a serious ischemic cardiomyopathy (ICMP), coronary revascularization to viable myocardium, LV reduction and mitral reconstruction become the main surgery under the bad conditions that the cardiac transplantaton is not so easy. The MR in ischemic cardiomyopathy appears as various pathologic factors, among them, the papillary muscle displacement in addition to the annular dilatation is pointed out as the important cause. Our hospital would like to report the experience of the surgery about coronary revascularization to the left main with 3-vessel coronary disease, severe ICMP patients accompanied with the MR, posterior mitral annuloplasty and papillary muscle plication through the LVtomy.
Cardiomyopathies* ; Coronary Disease ; Dilatation ; Heart Ventricles* ; Humans ; Mitral Valve Annuloplasty ; Mitral Valve Insufficiency* ; Myocardial Ischemia ; Myocardium ; Papillary Muscles*