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Results for “Papillary Muscles”

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At least 343 records · Page 19Linked to original sources

PubMed2006

[Partial papillary muscle ruptures complicating acute myocardial infarctions. Diagnosis by transesophageal echocardiography].

Partial papillary muscle rupture is a rare but fatal mechanical complication of acute myocardial infarction. Survival depends on prompt recognition and immediate medical and surgical therapy. The partial rupture of an anterolateral papillary muscle was clearly diagnosed by transgastric two-chamber view during TEE in a 64-year-old man who suffered from acute myocardial infarction.

Cardiomyopathies↗

PubMed1995

[Papillary muscle rupture in myocardial infarction].

We report nine patients with acute mitral regurgitation secondary to post-infarction papillary rupture operated between 1980 and 1992. Seven cases had posterior papillary muscle rupture. All patients were in critical conditions with pulmonary edema at the moment of surgery. In eight cases, mitral valve replacement was performed (4 with mechanical prostheses) and in one, the valve was repaired with papillary muscle reimplantation. Six cases were also subjected to myocardial revascularization with sapheneous vein grafts. Two patients (22%) died during the postoperative period and 4 had postoperative complications. The seven survivors have been followed during 6 to 115 month. Of theses, one died six month after surgery due to congestive heart failure, three are in functional class I and the rest in functional class II. It is concluded that, although mitral valve replacement for papillary muscle rupture has a high operative mortality and morbidity, long term results are satisfactory.

Aged↗

PubMed1983

Factors affecting the metabolism of resting rabbit papillary muscle.

The rate of resting heat production of 12 right ventricular rabbit papillary muscles was measured myothermically. Resting heat rate was measured at 4 temperatures (15, 20, 25 and 30 degrees C) in either 45% or 95% O2 while the muscle was passively stretched with various pre-loads. The metabolic substrate was pyruvate (10 mmol X 1(-1)). The mean resting heat rate, averaged across all treatment conditions, was 2.88 mW/g with no significant difference between the two oxygen concentrations. The calculated Q10 of the resting heat rate was surprisingly low--only about 1.4--but is shown to be in general agreement with literature values from whole heart oxygen consumption studies when the time-dependent decline is taken into account. Stretching the muscle beyond its rest length increased the rate of resting heat production. This response appeared unrelated to muscle diameter. The results are discussed in terms of the possible diffusion limitation of isolated papillary muscle preparations.

Animals↗

PubMed1978

[Behaviour of ATP and lactate in human papillary muscle during profound hypothermia and injection cardioplegia with magnesium-asparatate-procaine (author's transl)].

In 53 patients with mitral- or aortic-mitral valve disease, the content of ATP and lactate of the papillary muscles resected at the time of valve replacement was investigated at the beginning of ischemic arrest and at the time of reperfusion. Profound body hypothermia (25 degrees C) and injection cardioplegia using magnesium-aspartate-procaine were applied for myocardial protection. In hypertrophic papillary muscles the myocardial ATP content decreased at a slower rate (ATP decay 12% of the initial value after 60 minutes of ischemia) than in normal papillary muscles obtained from patients with isolated mitral stenosis (ATP decay 33% of the initial value after 40 minutes of ischemia). 20% of the patients required temporary inotropic circulatory support postoperatively for 12 to 88 hours. The ATP content of the papillary muscles of these patients differed only little from those, in who no myocardial failure occurred. However the myocardial lactate levels were higher in patients in whom a low cardiac output state evolved.

Adenosine Triphosphate↗

PubMed1990

Electrophysiological effects of m-nisoldipine and nisoldipine on papillary muscles of guinea pig.

UNLABELLED: The effects of m-nisoldipine (m-Nis) and nisoldipine (Nis) on action potentials of papillary muscles in guinea pigs were studied using intracellular microelectrodes. THE RESULTS: (1) APD and Vmaxs in normal papillary muscles were reduced by m-Nis and Nis. However, the APA, Vmaxf and overshoot were not affected. (2) In the partially depolarized papillary muscles, the APA, overshoot, Vmax and APD were depressed in a dose-dependent manner. The inhibitory effects of Nis on APA, APD50 and PPD were greater than those of the m-Nis. (3) There was a good correlation between APD50 and PPD derived from a linear regression. By the linear equation, PPD was easily calculated from APD50.

Action Potentials↗

PubMed1975

Effects of papaverine on isolated rabbit papillary muscle.

The effect of papaverine on the positive inotropic response to isopreqaline and to calcium was studied on the rabbit isolated papillary muscle; theophylline and the calcium antagonistic D600 were used for comparison. The dose-response curve for isoprenaline was shifted to the left by papaverine (3 times 10- minus 6 to 3 times 10- minus 5 M), in a dose-dependent manner, while that for calcium was not affected by the same concentration. In this respect papaverine was about 30 times more potent than theophylline. In the presence of papaverine isoprenaline induced arrhythmic contractions of the papillary muscle: the incidence of arrhythmic contractions was positively correlated to the concentration of papaverine. Papaverine 10- minus 5 to 10- minus 4 M caused only a positive inotropic response whereas 3 times 10- minus 4 to 10- minus 3 M induced a biphasic response, i.e., after a positive inotropic effect followed a negative one. In the presence of 3 times 10- minus 4 M papaverine isoprenaline failed to cause a positive inotropic response but exclusively induced arrhythmic contractions. Calcium, on the other hand, readily antagonized the negative inotropic effect of papaverine (3 times 10- minus 4 M) and caused a contracture of the papillary muscle. The results indicate that papaverine (3 times 10- minus 6 to 10- minus 5 M) like theophylline (10- minus 4 to 10- minus 3 M) produces its effect by phosphodiesterase inhibition and thereby specifically potentiates the response through beta-adrenoceptor stimulation. In higher concentrations (3 times 10- minus 4 to 10- minus 3 M) it acts as a calcium antagonistic, like D600, and furthermore may interact with calcium moving through myocardial cell membranes to cause a contracture via a mechanism which it shares with theophylline.

Animals↗

PubMed1990

Single papillary muscle ("parachute valve") and double-orifice left ventricle in atrioventricular septal defect convergence of chordal attachment: surgical anatomy and results of surgery.

A review of 59 anatomical specimens and of the findings in 65 surgically repaired patients with atrioventricular septal defect (AVSD), revealed four patients with a single papillary muscle and 11 with a double-orifice left ventricle. A single papillary muscle of the left ventricle occurred in 1.7% (1 of 59) of the anatomical specimens, and 6% (4 of 65) of the surgical cases. A double orifice of the left ventricle was found in 13.6% (8 of 59) of the anatomical specimens, and 7.7% (6 of 65) of the surgical cases. A single papillary muscle was only seen in cases with a complete defect. Double orifice was associated with partial, complete, or intermediate type of defect, with the highest incidence in the intermediate forms: 40% (4 of 10) of the anatomical specimens and 22% (2 of 9) of the surgical cases. In the anatomical study the specimens, with either single papillary muscle or double-orifice left ventricle, appear to be variants of the same malformation characterized by convergence of chordal insertion and underdevelopment of the left lateral leaflet. Pathology belonging to this spectrum was seen in 15% of our autopsy specimens and 14% of the surgical cases. In the surgical series good operative results were obtained with a conservative approach in cases with a favorable surgical anatomy.

Adolescent↗

PubMed2003

[Effects of Rbl on action potentials and force of contraction in guinea pig ventricular papillary muscles].

OBJECTIVE: To evaluate the effects of Rbl on action potentials and force of contraction in guinea pig ventricular papillary muscles. METHOD: The ventricular papillary muscles of guinea pig were isolated regularly and immersed with Tyrode, s solution. The effects of Rbl (purified saponins of panaxnotoginseng) on the action potentials (AP), the slow action potentials and the force of contraction (FC) of the muscles were studied. The AP and FC were measured synchronously. RESULT: Rbl shortened the duration of AP, including APD2O and APD90, and reduced the FC(n = 5, P < 0.01), but didn't affect the rest potential (RP), the amplitude of action potential (APA), overshot (OS) and maximal upstrok velocity (Vmax). Rbl also decreased the APA of slow action potential, but quinidine had no such effects. CONCLUSION: Rbl may be a channel blocker.

Action Potentials↗

PubMedDate not supplied

Long-term voluntary ethanol consumption induces impairment of the mechanical performance in the papillary muscle of Sardinian alcohol-preferring rats.

The effects of chronic (26 weeks) ethanol consumption on cardiac muscle contractility in Sardinian alcohol-preferring drinkers (sP-D) and Sardinian alcohol-preferring naive (sP-N) rats were investigated. Experiments were carried out 1 week after ethanol administration ceased. Length-tension and force-frequency responses in left ventricular papillary muscles from both sP-D and sP-N rats were recorded in vitro. Papillary muscles were gradually stretched in steps of 5% of the reference (initial) length (L(r)) from 100 to 130% L(r). In sP-D rats, length-tension relationships showed a significant reduction in active tension: at optimal length for maximum active tension (130% L(r)), the developed force value (1.38 +/- 0.36 mN/mg, dry tissue) was 54% lower than that found in sP-N rats (3.16 +/- 0.6 mN/mg, dry tissue). In sP-D papillary muscles, a decrease in contractile behaviour was also observed in force-frequency responses (0.03-120 pulse/min), when compared with sP-N rats; developed force was found to be reduced by about 2.5 times. These results indicate that long-term ethanol consumption impairs the mechanical performance of sP papillary muscle, inducing a negative inotropic effect.

Alcohol Drinking↗

PubMed1989

Effects of beta-adrenoceptor blocking agents on isolated atrial and papillary muscles from experimentally diabetic rats.

Effects of propranolol and atenolol on isoproterenol-induced responses of isolated atrial and papillary muscles from experimentally diabetic rats were examined. Male Sprague-Dawley rats were divided into the diabetic group (DM) which received streptozotocin 60 mg/kg, i.v. and the control group (C) which received vehicle i.v. At 6 weeks after, the right atrial or right ventricular papillary muscle was isolated, and the beating rate (R) in the atrium or isometric force development (F) and its first derivatives (+/- dF/dt) in the papillary muscle under pacing were recorded. Basal R was less frequent in DM than in C, but ED50 values for isoproterenol-induced chronotropy were not different between the two groups. Basal F and basal +/- dF/dt were not different between the two groups, but isoproterenol-induced increases in F and +/- dF/dt were less in DM than in C. ED50 values in F and +dF/dt were not different between the two groups. Propranolol and atenolol shifted the concentration-response curves in R, F and +/- dF/dt for isoproterenol to the right in both groups. pA2 values of propranolol and atenolol for each parameter were not different between the two groups. Results indicate that propranolol and atenolol exert the same beta-adrenoceptor blocking potency in both diabetic and non-diabetic hearts of rats.

Animals↗

PubMed1987

[Experimental production of mitral valve and papillary muscle lesions by cervical vagus stimulation in rabbits].

Mitral valve and papillary muscle lesions were experimentally produced in rabbits by cervical vagal stimulation or compression of the abdominal aorta. The involvement induced the similar findings to mitral valve prolapse in human beings including mid-systolic clicks and a late systolic or holosystolic murmur. Extrasystoles were also common. Necropsies disclosed papillary muscle swelling, bleeding and edematous change in the mitral valve, swelling of the myocardial cells and interstitial fibrosis. Further, bacterial endocarditis was induced in such rabbits by injecting pseudomonas alkaligenes. Possible connection of experimentally-induced lesions of the mitral complex and mitral valve prolapse in human beings was discussed.

Animals↗

PubMed1984

Cardiac and hemodynamic effects of the centrally acting analgesics tramadol and pentazocine in anaesthetized rabbits and isolated guinea-pig atria and papillary muscles.

Cardio-hemodynamic and direct cardiac effects of 1-(m-methoxyphenyl)-2-(dimethylaminomethyl)- cyclohexan -1-ol (tramadol, Tramal ), and pentazocine were investigated in anaesthetized rabbits and in isolated guinea-pig atria and papillary muscles. Tramadol in anaesthetized rabbits at 1 and 4.64 mg/kg i.v. slightly increased arterial blood pressure and heart rate and at 10 mg/kg i.v. transiently decreased blood pressure, LV dp/dtmax and cardiac output and increased LV enddiastolic pressure. Pentazocine at 1 mg/kg i.v. increased blood pressure and peripheral vascular resistance, while with 2.15 and 4.64 mg/kg exerted dose-dependent cardiodepressive effects with initial fall of blood pressure, heart rate, LV dp/dtmax and cardiac output and increase of LV enddiastolic pressure. In spontaneously beating atria and electrically driven papillary muscles tramadol in the concentration range from 1 X 10(-6)-1 X 10(-4) mol/l showed concentration-dependent positive inotropic effects which where abolished and reversed to negative inotropic actions in catecholamine-depleted papillary muscles. In contrast, pentazocine in the same concentration range showed pure negative inotropic and negative chronotropic effects which were intensified in catecholamine-depleted papillary muscles. These in vitro results suggest that both tramadol and pentazocine interact with endogenous catecholamines in a way counteracting direct negative inotropic effects. While in the case of tramadol the sum of both properties leads to positive inotropic effects at least in vitro, with pentazocine negative inotropic action prevails.

Anesthesia↗

PubMed1998

Diazepam potentiates the positive inotropic effects of histamine and forskolin in guinea-pig papillary muscles.

There have been diverse reports on the effects of diazepam on cardiac contractility. The purpose of this study was to examine whether diazepam modifies the inotropic response elicited by histamine on an isolated guinea-pig papillary muscle. The responses of electrically driven papillary muscle to histamine and cyclic AMP-related inotropic agents were recorded in the absence and in the presence of diazepam. Histamine and forskolin, which directly stimulate adenylate cyclase, significantly increased the contractile force in the papillary muscle in a concentration-dependent manner. A histaminergic H2-receptor antagonist, cimetidine, but not a H1-receptor antagonist, diphenhydramine, at 10 microM produced a rightward shift in the concentration-response curve for histamine. Diazepam (10 microM) shifted the concentration-response curve for histamine and forskolin to the left by 1.8 and 1.6 times, respectively. Neither a central type (fulmazenil) nor a peripheral type (PK11195) of benzodiazepine receptor antagonist modified the effect of diazepam on the histaminergic-evoked contraction. Phosphodiesterase blockade by 3-isobutyl-1-methylxanthine shifted the concentration-dependent curve for histamine to the left. A combination of 3-isobutyl-1-methylxanthine also produced a leftward shift of the curve. However, there was no significant difference between the 3-isobutyl-1-methylxanthine only group and the combination group. These results indicate that diazepam potentiates the positive inotropic effect produced by histamine, probably mediated via an increase in cyclic AMP levels induced by histamine.

Anesthetics, Intravenous↗

PubMed1980

Intracellular chloride activity in quiescent cat papillary muscle.

Intracellular chloride activity (alpha iCl) was measured in quiescent cat papillary muscles with chloride liquid ion-exchanger microelectrodes. Muscles were superfused in bicarbonate-buffered solutions containing a control concentration of chloride (146.1 mM) and either 2.7, 4.4, or 5.4 mM potassium. The resulting mean membrane potentials were -96.2, -86.8, and -80.6 mV, respectively. In contrast, alpha iCl and the chloride equilibrium potential were unchanged by these alterations in external potassium and remained stable at 11 mM and -60 mV for up to 10 h following removal of the tissue from the animal. This value of alpha iCl is approximately 2-4 times greater than that predicted assuming chloride is passively distributed. The upper limit of intracellular interference was estimated from low external chloride superfusion and found to be no greater than 2-3 mM. Prolonged exposure to bicarbonate-free solutions buffered with N-2-hydroxyethyl piperazine-N'-2-ethanesulfonic acid (HEPES) did not reduce the apparent value of alpha iCl, suggesting that intracellular interference from intracellular bicarbonate does not significantly influence the measurement of alpha iCl. These results suggest that chloride can move into cat papillary muscle against an electrochemical gradient.

Animals↗

PubMed1988

Hypothermic effects on action potential and force production of hedgehog and guinea pig papillary muscles.

Action potentials and isometric force were recorded in papillary muscles from guinea pigs and summer hedgehogs at different temperatures between 37 and 0 degrees C. The action potential of the hedgehog was of a lower amplitude (mean 83 +/- 6 mV) than that of the guinea pig (mean 110 +/- 5 mV). The action potential duration at 50% repolarization was 22 +/- 2 msec in the hedgehog as compared to 105 +/- 11 msec in the guinea pig. Moreover, there was no distinct plateau phase of the hedgehog action potential. Lowering temperature prolonged the action potential duration in the two preparations by about the same percentage. However, the guinea pig preparation became progressively less excitable below 20 degrees C. Lowered temperature produced a positive inotropic effect in the guinea pig, whereas this effect was very slight in the hedgehog heart. Postextrasystolic potentiation was seen in the guinea pig but not in the hedgehog preparation. It is suggested that this difference between the preparations may be due to a greater relative amount of activator calcium in the hedgehog heart. The difference in cold tolerance between the preparations may reflect a difference in chemical composition of the sarcolemma.

Action Potentials↗

PubMed1977

Non-uniform strain distribution in papillary muscles.

Measurements of surface strains were made on small segments of intact papillary muscles of cats and rabbits. The measured strain is found to be non-uniform, both along the length and across the diameter of the papillary. This observation introduces difficulty in interpreting the data from experiments on the mechanics of the papillary muscle.

Animals↗

PubMed1991

Enhancement of amrinone-induced positive inotropy in rabbit papillary muscles with depressed contractile function: effects on cyclic nucleotide levels and phosphodiesterase isoenzymes.

The inotropic activity of amrinone and its effects on cyclic nucleotide levels in rabbit papillary muscles with normal and depressed contractile function have been compared. The effects of amrinone on the cyclic (c) AMP hydrolytic activity of cyclic nucleotide phosphodiesterase (PDE) isoenzymes were also examined. Amrinone (2.4 x 10(-4) - 1.2 x 10(-3) M) produced a relatively weak (maximal increase 11%) positive inotropic effect in papillary muscles stimulated at the near optimal stimulation frequency of 1 Hz. In contrast, large positive inotropic responses (maximal 138-200%) were obtained with amrinone in papillary muscles in which contractile force had been depressed by: (a) lowering stimulation frequency to 0.4 Hz, (b) reducing extracellular Ca2+ concentration from 2.5 x 10(-3) M to 6.3 x 10(-4) M, (c) prior addition of sodium pentobarbitone (6.5 x 10(-4) M). The EC50 values for amrinone under conditions (a), (b), and (c) were 3.0 x 10(-3), 2.6 x 10(-3), and 2.8 x 10(-3) M, respectively. Force-frequency curves in rabbit papillary muscles were compared at normal (2.5 x 10(-3) M) and low (6.3 x 10(-4) M) extracellular Ca2+ concentration. Contractions at low frequencies of stimulation (less than 0.4 Hz) were less sensitive to removal of extracellular Ca2+ than higher stimulation rates indicating that in the former situation, recycling of intracellular Ca2+ is more important for maintaining contractile force.(ABSTRACT TRUNCATED AT 250 WORDS)

Amrinone↗

PubMed1979

Cross-sectional echocardiographic spectrum of papillary muscle dysfunction.

Cross-sectional echocardiography identified two abnormal patterns of mitral valve closure in 14 patients with mitral regurgitation due to papillary muscle dysfunction: (1) in three patients with an akinetic inferior-posterior wall but normal cavity size, papillary muscle fibrosis was associated with late systolic mitral valve prolapse, and (2) in nine patients with ventricular dilatation or ventricular aneurysm, the point of mitral valve coaptation was displaced towards the apex of the left ventricle. In two of these patients both abnormalities were observed. In contrast, abnormal patterns were identified in only four of a group of 40 patients without angiographic evidence of mitral regurgitation (10, normal; 27, coronary artery disease; three, congestive cardiomyopathy). Thus, cross-sectional echocardiography can be useful to identify mitral regurgitation secondary to papillary muscle dysfunction.

Aged↗