OBJECTIVE: To evaluate the influence of papillary muscles and trabeculae on left ventricular (LV) cardiovascular magnetic resonance (CMR) analysis using three methods of cavity delineation (classic or modified inclusion methods, and the exclusion method) in patients with hypertrophic cardiomyopathy (HCM). MATERIALS AND METHODS: This retrospective study included 20 consecutive HCM patients who underwent 1.5-T CMR imaging with short-axis cine stacks of the entire LV. LV measurements were performed using three different methods of manual cavity delineation of the endocardial and epicardial contours: method A, presumed endocardial boundary as seen on short-axis cine images; method B, including solely the cavity and closely adjacent trabeculae; or method C, excluding papillary muscles and trabeculae. Ascending aorta forward flow was measured as reference for LV-stroke volume (SV). Interobserver reproducibility was assessed using intraclass correlation coefficients. RESULTS: Method A showed larger end-diastole and end-systole volumes (largest percentage differences of 25% and 68%, respectively, p < 0.05), compared with method C. The ejection fraction was 55.7 +/- 6.9% for method A, 68.6 +/- 8.4% for B, and 71.7 +/- 7.0% for C (p < 0.001). Mean mass was also significantly different: 164.6 +/- 47.4 g for A, 176.5 +/- 50.5 g for B, and 199.6 +/- 53.2 g for C (p < 0.001). LV-SV error was largest with method B (p < 0.001). No difference in interobserver agreement was observed (p > 0.05). CONCLUSION: In HCM patients, LV measurements are strikingly different dependent on whether papillary muscles and trabeculae are included or excluded. Therefore, a consistent method of LV cavity delineation may be crucial during longitudinal follow-up to avoid misinterpretation and erroneous clinical decision-making.
Adult ; Aged ; Cardiomyopathy, Hypertrophic/*pathology ; Female ; Heart Ventricles/physiopathology/*radiography ; Humans ; *Magnetic Resonance Imaging, Cine ; Male ; Middle Aged ; Papillary Muscles/*physiopathology ; Retrospective Studies ; Stroke Volume/physiology ; Systole/physiology

OBJECTIVETo investigate the electrophysiological changes of ventricular myocardium of rats with experimental diabetes and the effect of adenosine on its electrophysiology.

METHODSDiabetes was induced in male SD rats, using a single injection of alloxan into tail vein. Untreated animals were used as controls. The electrocardiograms (ECG) were recorded 6 weeks after diabetes was induced. Effects of adenosine on ventricular myocardium in diabetic rats and controls were observed by measuring the transmembrane potentials with conventional glass microelectrodes.

RESULTSQT interval in ECG and action potential duration (APD) at all levels (APD30, APD50, APD70 and APD90) were significantly prolonged in right ventricular papillary muscle 6 week after diabetes was induced. No differences were observed in the resting membrane potential (RP), action potential amplitude (APA) and overshoot (OS) as well as the maximum rate of depolarization (Vmax) between the diabetic rats and control rats. At concentration of 10 approximately 400 micromol/L, ADO had little influence on all transmembrane potential parameters of right ventricular papillary muscle in diabetic rats and controls. At 500 micromol/L, ADO shortened APD30, APD50, APD70 and APD90 of control group, while having no effect on diabetic rats.

CONCLUSIONQT interval in ECG and APD at all levels are significantly prolonged in right ventricular papillary muscle of experimentally induced-diabetic rats.

Action Potentials ; drug effects ; Adenosine ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Diabetes Mellitus, Experimental ; physiopathology ; Electrocardiography ; Electrophysiology ; Male ; Papillary Muscles ; physiology ; Rats ; Rats, Sprague-Dawley ; Ventricular Function

The purpose of the present study was to investigate the effect of chronic intermittent hypobaric hypoxia (CIHH) on α(1)-adrenergic receptors and the role of alpha(1)-adrenergic receptors in the protection of CIHH against ischemic injury of myocardium. Sixty-six adult male Sprague-Dawley rats were randomly divided into four groups: control group (Con), 14-day CIHH treatment group (CIHH14), 28-day CIHH treatment group (CIHH28) and 42-day CIHH treatment group (CIHH42). CIHH rats were exposed to hypoxia mimicking 5 000 m altitude (p(B)=404 mmHg, p(O(2))=84 mmHg) in a hypobaric chamber, 6 h daily for 14, 28 and 42 d, respectively. Control animals lived in the same environment as CIHH animals except hypoxia exposure. After anesthesia with sodium pentobarbital (3.0-3.5 mL/kg body weight, i.p.), papillary muscle was taken from the right ventricle of rat and perfused with modified Tyrode's solution continuously, at constant temperature (37 °C) and perfusion speed (12 mL/min). Muscle contraction was evoked by electric stimuli. Different concentrations (1x10(-7), 1x10(-6) and 1x10(-5) mol/L) of phenylephrine (PE), an alpha(1)-adrenergic receptor agonist, were applied cumulatively to investigate the effect of PE on the mechanic contraction of right ventricular papillary muscles of rats in Con, CIHH14, CIHH28 and CIHH42 groups. Also, prazosin (1x10(-6) mol/L), an α(1)-adrenergic receptor antagonist, was used to investigate the role of α(1)-adrenergic receptor in the protective effect of CIHH on papillary muscle. The results showed: (1) PE increased the maximal isometric tension (P(max)) and maximal velocity of tension development (P(dT/dt)) of muscle contraction in a dose-dependent manner (P<0.05), and the increase of the muscle contraction was much greater in CIHH28 and CIHH42 rats than that in Con rats (P<0.05). Under 1x10(-5) mol/L of PE, the increases of P(max) and P(dT/dt) over the baseline were 51.2% and 44.5% in CIHH28 group, 48.6% and 44.5% in CIHH42 group, and 28.7% and 24.5% in Con group, respectively; (2) The contraction of papillary muscle decreased during simulated ischemia, but the decrease was slighter in CIHH rats than that in Con rats (P<0.05). The decreases in P(max) and P(dT/dt) were 59.6% and 53.6% in CIHH28 group, 60.4% and 49.9% in CIHH42 group, and 74.4% and 64.7% in Con group, respectively; (3) The protective effect of CIHH on ischemic papillary muscle was abolished by prazosin (1x10(-6) mol/L). The results of the present study suggest that CIHH increases the activity of α(1)-adrenergic receptor, which is possibly one of the mechanisms for the cardioprotection of CIHH.
Altitude ; Animals ; Heart Ventricles ; physiopathology ; Hypoxia ; metabolism ; Male ; Muscle Contraction ; Myocardium ; metabolism ; Papillary Muscles ; metabolism ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, alpha-1 ; metabolism

This study is to evaluate the effects of Shenmai injection on the temporal alterations of action potential (AP), early afterdepolarization (EAD) and delayed afterdepolarization (DAD) in papillary muscles. The action potentials were recorded by a glass electrode. APD at 90% repolarization (APD9 ) was measured, and spontaneous EAD and DAD were observed. The results show APD90 was significantly prolonged in model group compared with sham-operated group, whereas it was remained unchanged in Shenmai injec- tion treatment group and amiodarone group. The spontaneous EADs and DADs were frequently visible in model group. In conclusion, EAD, DAD and trigger activities increase gradually during pathological progression of rat cardiac hypertrophy, and Shenmai injection could improve the action potential change in rat cardiac hypertrophy.
Action Potentials ; drug effects ; Animals ; Blood Pressure ; drug effects ; Cardiomegaly ; physiopathology ; Drug Combinations ; Drugs, Chinese Herbal ; administration & dosage ; pharmacology ; Heart Ventricles ; drug effects ; physiopathology ; Injections ; Male ; Papillary Muscles ; drug effects ; physiopathology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo study the effect of Ginkgo biloba extract 50 (GBE50), a new multicomponent drug with a polyvalent action extracted from the leave of Ginkgo biloba, on the action potentials in normal and simulated ischemic guinea pig papillary muscles.

METHODStandard intracellular microelectrode technique was used to examine the effects of GBE50 on the action potential parameters [action potential amplitude (APA), overshoot, rest potential, action potential amplitude at 20%, 50%, 90% of repolarization (APD20, APD50, APD90)].

RESULTIn normal guinea pig cardiac papillary muscles, GBE50 (20, 50, 100 mg x L(-1)) shortened APD50 and APD90, and did not affect the rest potential parameters. In simulated ischemic guinea pig cardiac papillary cells, action potential duration was significantly shortened, resting potential and action potential amplitude were reduced. 100 mg x L(-1) GBE50 partly attenuated the change induced by ischemia.

CONCLUSIONGBE50 shortened APD of normal guinea pig cardiac papillary cells in a concentration-dependent manner. Under ischemia, all action potential parameters were reduced . GBES0 could alleviate the electrophysiological heterogeneity of ischemic myocardium, which may attenuate myocardial ischemia and block the onset of arrhythmia.

Action Potentials ; drug effects ; Animals ; Disease Models, Animal ; Ginkgo biloba ; chemistry ; Guinea Pigs ; Humans ; Male ; Myocardial Ischemia ; drug therapy ; physiopathology ; Papillary Muscles ; drug effects ; physiology ; physiopathology ; Plant Extracts ; administration & dosage ; Random Allocation

INTRODUCTIONPapillary muscle rupture and dysfunction can lead to complications of prolapsed mitral valve and mitral regurgitation. Multiple operative procedures of the papillary muscles, such as resection, repositioning and realignment, are carried out to restore normal physiological function. Therefore, it is important to know both the variations and the normal anatomy of papillary muscles.

METHODSThis study was carried out on 116 human cadaveric hearts. The left ventricles were opened along the left border in order to view the papillary muscles. The number, shape, position and pattern of the papillary muscles were observed.

RESULTSIn this series, the papillary muscles were mostly found in groups instead of in twos, as is described in standard textbooks. Four different shapes of papillary muscles were identified - conical, broad-apexed, pyramidal and fan-shaped. We also discovered various patterns of papillary muscles.

CONCLUSIONNo two mitral valve complexes have the same architectural arrangement. Each case seems to be unique. Therefore, it is important for scientists worldwide to study the variations in the mitral valve complex in order to ascertain the reason behind each specific architectural arrangement. This will enable cardiothoracic surgeons to tailor the surgical procedures according to the individual papillary muscle pattern.

Adult ; Anatomy ; methods ; Cadaver ; Chordae Tendineae ; anatomy & histology ; Heart ; anatomy & histology ; Humans ; Middle Aged ; Mitral Valve ; pathology ; Mitral Valve Insufficiency ; physiopathology ; Models, Anatomic ; Papillary Muscles ; pathology ; Thoracic Surgery ; methods

OBJECTIVETo explore the possible mechanism of cyclovirobuxine D (CVB-D) in countering and inducing arrhythmia, by way of studying its electro-physiological effect on ventricular papillary muscles of rats in vitro.

METHODSThe transmembrane potential of rat's isolated right ventricular papillary muscles were recorded using conventional glass micro-electrode technique.

RESULTS(1) CVB-D in concentration of 13.3-63.3 micromol/L, showed prolonging effect on the action potential repolarization time, mainly the action potential duration 50 (APD50), APD70 and APD90, in dose-dependent manner, in concentration of 33.3-63.3 micromol/L, it could inhibit the resting potential, action potential amplitude (APA) and maximum depolarization velocity (Vmax) in dose-dependent manner. (2) CVB-D also showed time-dependent effect, the effect initiated 10 min after 20 micromol/L was perfused in ventricular muscle, the APD50, APD70 and APD90 were potentiated gradually along with prolongation of action time and reached the peak at 30-40 min, without any potentiation thereafter. (3) CVB-D could markedly prolong the effective refractory period (ERP) of action potential, increase the ratio of ERP/APD. (4) CVB-D in concentration of 33.3 micromol/L could induce frequent, multifocal spontaneous arrhythmia in some cells when the action time was longer than 45 min.

CONCLUSIONCVB-D has the action of anti-ventricular arrhythmia, the mechanism is correlated with the prolongation of APD and ERP of ventricular muscle as well as the increase of ERP/APD ratio, while it also has the effect of inducing arrhythmia, the mechanism might be concerned with excessive prolongation of APD and the inhibition on RP, APA and Vmax.

Action Potentials ; drug effects ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrhythmias, Cardiac ; chemically induced ; physiopathology ; Drugs, Chinese Herbal ; pharmacology ; Electrophysiologic Techniques, Cardiac ; Heart Ventricles ; drug effects ; In Vitro Techniques ; Male ; Myocytes, Cardiac ; cytology ; Papillary Muscles ; drug effects ; Rats ; Rats, Sprague-Dawley ; Refractory Period, Electrophysiological ; drug effects ; Ventricular Function

To study the antiarrhythmic effect of the newly developed alpha/beta-blocker TJ0711, a variety of animal models of arrhythmia were induced by CaCl2, ouabain and ischemia/reperfusion. Glass microelectrode technique was used to observe action potentials of right ventricular papillary muscle of guinea pig. The onset time of arrhythmia induced by CaCl2 was significantly prolonged by TJ0711 at 0.75, 1.5 and 3 mg x kg(-1) doses. TJ0711 (1.5 and 3 mg x kg(-1)) can significantly shorten the ventricular tachycardia (VT) and ventricular fibrillation (VF) duration, the incidence of VF and mortality were significantly reduced. On ischemia-reperfusion-induced arrhythmic model, TJ0711 (0.25, 0.5, 1 and 2 mg x kg(-1)) can significantly reduce the ventricular premature contraction (PVC), VT, VF incidence, mortality, arrhythmia score with a dose-dependent manner. At the same time, rats serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities decreased significantly by TJ0711 (1 and 2 mg x kg(-1)). Ouabain could cause arrhythmia in guinea pigs, when TJ0711 (0.375, 0.75, 1.5 and 3 mg x kg(-1)) was given, the doses of ouabain inducing a variety of arrhythmia PVC, VT, VF, cardiac arrest (CA) were significantly increased with a dose-dependent manner. In the TJ0711 0.1-30 micromol x L(-1) concentration range, guinea pig right ventricular papillary muscle action potential RP (rest potential), APA (action potential amplitude) and V(max) (maximum velocity of depolarization) were not significantly affected. APD20, APD50 and APD90 had a shortening trend but no statistical difference with the increase of TJ0711 concentration. TJ0711 has antiarrhythmic effect on the sympathetic nerve excitement and myocardial cell high calcium animal arrhythmia model. Myocardial action potential zero phase conduction velocity and resting membrane potential were not inhibited by TJ0711. APD20, APD50 and APD90 were shortened by TJ0711 at high concentration. Its antiarrhythmic action mechanism may be besides the action of blocking beta1 receptor, may also have a strong selective blocking action on alpha1 receptor and reducing intracellular calcium concentration.
Action Potentials ; drug effects ; Adrenergic alpha-Antagonists ; administration & dosage ; pharmacology ; Adrenergic beta-Antagonists ; administration & dosage ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; administration & dosage ; pharmacology ; Arrhythmias, Cardiac ; blood ; chemically induced ; etiology ; pathology ; physiopathology ; Calcium Chloride ; Creatine Kinase ; blood ; Dose-Response Relationship, Drug ; Female ; Guinea Pigs ; Heart Ventricles ; cytology ; Lactate Dehydrogenases ; blood ; Male ; Myocardial Reperfusion Injury ; complications ; Myocytes, Cardiac ; drug effects ; physiology ; Ouabain ; Papillary Muscles ; cytology ; Phenoxypropanolamines ; administration & dosage ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley