Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Atrial Function, Right”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,585 records · Page 88Linked to original sources
PubMed1994

Mechanosensitive fibroblasts in the sino-atrial node region of rat heart: interaction with cardiomyocytes and possible role.

The positive chronotropic response of the heart to stretch of the right atrium is one of the major mechanisms adjusting the heart rate to variations in venous return on a beat-by-beat basis. The precise pathway of this mechano-electric feedback and its cellular basis are uncertain. In this study, a possible contribution of mechanosensitive fibroblasts, abundant in the sino-atrial node region, was investigated using a mathematical model of the electrical interaction of a mechanosensitive fibroblast and a sino-atrial pacemaker cell. Electrophysiological evidence for a bio-electrical interaction of mechanosensitive fibroblasts with surrounding cardiomyocytes has been studied in (i) the isolated spontaneously beating atrium of rat hearts, and (ii) cell cultures of the neonatal rat heart. These investigations were performed using (i) double-barrelled floating microelectrodes for intracellular potential registrations, and (ii) the double whole cell patch-clamp technique. It was shown that cardiac fibroblasts and surrounding cardiomyocytes can be either electrically well isolated from each other, or coupled both capacitively and electrotonically. The electrophysiological data obtained were incorporated into the OXSOFT HEART program. Assuming that equivalent coupling may occur between mechanosensitive fibroblasts and sino-atrial pacemaker cells, a heterologous cell pair consisting of one fibroblast and one sino-atrial node myocyte connected by ten to thirty single gap junctional channels with a conductance of 30 pS was modelled. The model of the electrotonic interaction of these cells showed that stretch of the fibroblast during atrial diastole, simulating increased atrial wall tension during atrial filling, can raise the spontaneous depolarization rate of the pacemaker cell in a stretch-dependent manner by up to 24%. These results show that cardiac mechanosensitive fibroblasts could form a cellular basis for the positive chronotropic response of the heart to stretch of the right atrium.

Animals↗
PubMed2001

Heart rate-independent vagal effect on end-systolic elastance of the canine left ventricle under various levels of sympathetic tone.

BACKGROUND: Although we have shown that in rabbits the direct (heart rate [HR]-independent) vagal effect on left ventricular end-systolic elastance (E(es)) was negligible under minimal sympathetic tone, how underlying sympathetic tone modulates the inotropic response to vagal stimulation remains unknown. METHODS AND RESULTS: We used an isolated canine heart preparation with functioning autonomic nerves. We examined the direct vagal inotropic effect by measuring E(es) under fixed-rate atrial pacing with or without concomitant sympathetic nerve stimulation. Right and left vagal stimulation at 20 Hz decreased HR by 27+/-3% and 14+/-2%, respectively, and decreased E(es) by 11+/-2% and 6+/-2%, respectively. When we fixed HR by atrial pacing, right and left vagal stimulation at 20 Hz did not decrease E(es) (0.01+/-0.3% and 0.3+/-0.4%; NS). Concomitant left sympathetic nerve stimulation at 4 Hz enhanced direct vagal negative inotropism to -19+/-3% and -34+/-5% for 20-Hz right and left vagal stimulation (interaction, P<0.01). CONCLUSIONS: Direct vagal negative inotropism was unobservable with minimal sympathetic tone in dogs but was enhanced with concomitant sympathetic stimulation.

Animals↗
PubMed1975

Etiology of the electrocardiographic pattern of "incomplete right bundle branch block" in atrial septal defect: an electrophysiologic study.

His bundle and right ventricular apical endocardial electrograms were recorded in 18 patients, ages five to 17 years, of whom ten had atrial septal defect of the secundum type and eight had mild aortic stenosis. The H-RVA interval was assumed to approximate conduction time from the level of the His bundle along the RBB to the site of earliest activation in the right ventricle at the RVA. The H-V interval was normal in all patients (less than or equal to 40 msec). All patients in the ASD group had an rsR' or rSr' pattern in Vl with a mean duration of 99 +/- 9 msec (86 to 116 msec); the mean duration of the H-RVA intervals was 54 +/- 6 msec in this group. In patients with AS, the surface electrocardiograms were normal, with a mean QRS duration of 82 +/- 8 msec (70 to 95 msec); the H-RVA intervals averaged 52 +/- 6 msec. The difference in the H-RVA intervals in the two groups was not statistically significant (P greater than 0.50) despite the fact that patients with ASD had significant prolongation of QRS duration (P greater than 0.001). Moreover, when functional RBB block was induced by premature atrial stimulation in the ASD group, the prolongation of QRS duration was accompanied by an increase in H-RVA interval, indicating relatively intact function of the RBB. It is concluded that the rsR' or rSr' pattern in ASD is likely to be a manifestation of right ventricular overload rather than a true conduction delay in the RBB.

Adolescent↗
PubMed1976

Ebstein's malformation. Surgical experience at the Mayo Clinic.

At the Mayo Clinic, 13 patients with Ebstein's malformation have undergone surgical repair since 1963. Their ages ranged from 18 months to 51 years (median 13 years). Ten patients were in Functional Class III or IV. Marked cardiomegaly, cyanosis, paradoxic emboli, and dysrhythmias secondary to Wolff-Parkinson-White syndrome were indications for operation in the remaining 3 patients. A wide range of anatomic variations was encountered. All 5 patients who underwent tricuspid annuloplasty with plication of the atrialized segment of the right ventricle survived operation. Of 5 patients who underwent prosthetic valve replacement, only one survived. Other procedures included atrial septal defect closure alone in one patient, atrial septal defect closure and relief of pulmonary stenosis in one patient, and tricuspid annuloplasty alone in one patient. One patient had concomitant mapping and division of anomalous conduction pathways. Functional classification improved in 8 of 10 operative survivors. There were two late sudden deaths; both patients had had preoperative dysrhythmias. The data suggest that results are improved when the atrialized segment of the right ventricle is dealt with during repair of the tricuspid valve. A combined ventricular plication and tricuspid annuloplasty yielded better early and late results than did valve replacement.

Adolescent↗
PubMed1990

Atrial septal defect after percutaneous mitral balloon valvuloplasty: immediate results and follow-up.

Percutaneous mitral balloon valvuloplasty was performed in 150 patients. There were 124 women and 26 men (mean age 53 +/- 1 years). A left to right shunt through the created atrial communication was present in 28 patients (19%) after valvuloplasty. The pulmonary to systemic flow ratio was greater than or equal to 2:1 in 4 patients and less than 2:1 in 24. Univariate predictors of left to right shunting after valvuloplasty included older age (p less than 0.01), lower cardiac output before mitral valvuloplasty (p less than 0.01), higher New York Heart Association functional class before valvuloplasty (p less than 0.05), presence of mitral valve calcification under fluoroscopy (p less than 0.01) and higher echocardiographic score (p less than 0.05). Multiple stepwise logistic regression analysis identified the presence of mitral valve calcification (p less than 0.02) and lower cardiac output (p less than 0.02) as the independent predictors of a left to right shunt through the atrial communication after balloon valvuloplasty. Follow-up (10 +/- 1 months) of patients with an atrial septal defect after valvuloplasty showed that 1) 6 patients died (3 in the hospital and 3 at 2, 16 and 18 months, respectively, after valvuloplasty); 2) an atrial septal defect was demonstrated in 3 of 6 patients who underwent mitral valve replacement (6 +/- 0.8 months after valvuloplasty); and 3) 13 patients were in functional class I, 2 patients were in class II and 1 patient was in class III at 13 +/- 1 months after valvuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Single-pump techniques for assisted circulation in cardiogenic shock: experimental evaluation and case report.

Acute cardiogenic shock or bridging to transplantation often involves the need for circulatory and cardiac support systems that are more effective than the intraaortic balloon pump. Biventricular failure, which is present in many cases, is generally treated with total cardiac replacement or with a complex of pumps and oxygenator that makes application difficult. With the goal of developing a universally applicable method of cardiac and circulatory support, we undertook a series of canine experiments designed to evaluate the effect of various treatment methods on survival, hemodynamics, and metabolic function. The series involved 123 dogs, in which cardiogenic shock was induced by means of multiple coronary artery ligations. The individual animals were then subjected to bypass, treated medically, or left untreated, depending on random selection. Each treatment lasted for 4 hours and was followed by a 2-hour period of observation. The following single-pump methods were tested: 1) left ventricular (LV) bypass, 2) left atrial (LA) bypass, 3) left ventricular and right atrial (LV + RA) bypass, 4) left atrial and right atrial (LA + RA) bypass, 5) LV + RA bypass, plus treatment with substrates (cysteine and ribose), and 6) LV + RA bypass, plus treatment with fluosol. Each bypass system incorporated a single reservoir and a centrifugal pump, and blood was returned to a femoral artery. Medical therapy consisted of either 1) treatment with sodium nitroprusside alone or 2) treatment with substrates alone. With respect to survival and hemodynamic effects (as reflected by oxygen consumption), LV + RA bypass and LA + RA bypass proved superior. During the posttreatment period, LV + RA bypass was associated with the highest survival rates and, therefore, with the most satisfactory recovery of myocardial or cardiac function. Despite the limited desaturation produced during venous shunting from the right atrium, perfusion of the entire body and consumption of oxygen were least in the LV + RA bypass group. The addition of substrates, or even of fluosol, caused a reduction in oxygen consumption. Our experience also includes one clinical case in which LA + RA bypass was used to support a 57-year-old man for 32 hours, after left atrial bypass alone proved inadequate. The dual-chamber technique brought about an improvement not only in hemodynamics but also in blood-gas values and pH. On the basis of this case and the canine experiments, we conclude that LV + RA and LA + RA bypass techniques offer safe, effective means of long-term temporary support for patients in severe cardiogenic shock.

Journal Article↗
PubMed1996

[Echocardiographic analysis of cardiac size and function in patients with severe obstructive sleep apnea].

The purpose of this study was to determine usefulness of non invasive echocardiographic measurements in patients with severe obstructive sleep apnea (OSA). Diagnosis of OSA was established by polysomnography. We investigated 18 patients (16M, 2F), mean age 45 +/- 10 years, mean weight 114 +/- 16 kg and mean apnea/hypopnea index 69 +/- 23. Two-dimensional (2D) and Doppler echocardiography (DOP) was used to assess: 1. Systolic function of left ventricle by determination of cardiac output (CO), ejection fraction (EF), 2. Diastolic function of left ventricle by calculation of mitral early diastolic velocity to arterial velocity ratio (Ev/Av) and atrial flow to total mitral flow ratio (AF/Tf), 3. Right ventricle thickness in systole (RVWS) and diastole (RVWD), and its diastolic diameter (RVD), 4. Pulmonary arterial pressure (PAP) by evaluation of acceleration time in the pulmonary artery (ACT) and tricuspid regurgitation jet velocity (TR). Results (mean +/- SD): Co 6.67 +/- 2.0 L/min, EF 44 +/- 5.6%, RVWS 10.9 +/- 1.3 mm, RVWD 6.7 +/- 1.1 mm, RVD 30.3 +/- 2.8 mm, Ev/Av 1.22 +/- 0.39, Af/Tf 0.38 +/- 0.11, AcT 121.4 +/- 20.3 ms. These data confirm that intermittent hypoxia and increased ventricular afterload cause both systolic and diastolic left ventricular dysfunction. Right ventricular hypertrophy found despite normal resting, wake, PAP could be probably attributed to transient pulmonary hypertension during repeatable nocturnal hypoxic episodes.

Adult↗
PubMed1999

A patient with hypertrophic cardiomyopathy accompanied by right ventricular dilation of unknown cause.

Hypertrophic cardiomyopathy (HCM) is a disease characterized by an unknown cause of hypertrophy in the left or right ventricle. The dilated phase of HCM shows disease conditions resembling dilated cardiomyopathy, such as ventricular dilation, thin ventricular wall, and reduction of the ejection fraction. A patient presented with left ventricular concentric hypertrophy accompanied by right ventricular dilatation of unknown cause. Right ventricular endomyocardial biopsy specimens showed characteristic myocardial disarray. Therefore, there is the possibility that the patient had right and left ventricular HCM in the process toward the dilated phase, in which dilatation first occurred in the right ventricle.

Atrial Fibrillation↗
PubMed1983

Effects of training on cardiorespiratory function in the horse.

The effects of 5- and 10-wk treadmill exercise training on cardiorespiratory function were evaluated in the horse. Cardiac output (Q), heart rate (HR), and stroke volume (SV), as well as left ventricular (LVP), aortic (AoP), and mean right atrial (RAP) pressures and the peak first time derivative of LVP (LV dP/dtmax), were measured at rest and at five different levels of exercise up to 90% of initial predicted maximal HR (HRmax). Oxygen uptake (VO2) and respiratory exchange ratio (R) were also obtained under the same conditions. At rest, although HR was no different after training, LV dP/dtmax was lower at 10 wk (2,369 +/- 502 vs. 1,615 +/- 302 mmHg/s). At the different measured work loads during exercise, Q and VO2 remained unchanged with training, whereas there were consistent trends toward lower LVP, AoP, and LV dP/dtmax and significant reductions in HR and R (both P less than 0.05). In contrast, SV and mean RAP were elevated (P less than 0.05) during exercise after the 10-wk training program. Although the observed changes in cardiorespiratory function in response to a training program in the horse are generally similar to those reported for other species, our data also suggest a training-induced increase in venous pressures during exercise as measured by elevated mean RAP values.

Animals↗
PubMed1994

Markedly enlarged right atrium associated with physical signs of tricuspid regurgitation--a cause of congestive heart failure in the elderly.

We retrospectively examined 8 patients who had classical physical signs of tricuspid regurgitation associated with congestive heart failure, the cause of which was not identified by echocardiography. Exclusion criteria were as follows; 1) peak velocity of tricuspid regurgitation greater than 3 m/sec, 2) disturbance of left ventricular wall motion, 3) severe mitral regurgitation and/or aortic regurgitation by color Doppler echocardiography, and 4) structural abnormalities of tricuspid and mitral valve complexes. The subjects had a mean age of 81 years and all showed atrial fibrillation without tachycardia. Radiocardiography showed no significant left-to-right shunt. Two-dimensional echocardiography showed a markedly enlarged right atrium and slight enlargement of the right ventricle in all patients. A signal of tricuspid regurgitation was seen throughout the markedly enlarged right atrium on color Doppler echocardiography. Although neither hypoxemia nor hypercapnea were found in any of the patients, pulmonary function tests done in 6 patients were all abnormal. In chest x-ray films, 6 of the patients showed evidence of marked protrusion of the right heart border progressing over the course of several years. Right atrial enlargement due to both long-standing atrial fibrillation and presumably, to right ventricular diastolic dysfunction caused by aging made the tricuspid valve annuls annulus dilate to produce tricuspid regurgitation. In addition, concomitant mild lung disease produced a vicious cycle which led to more severe tricuspid regurgitation resulting in severe congestive heart failure. This pathophysiology can be a cause of congestive heart failure in the elderly.

Aged↗
PubMed1975

Mechanisms of enhancement of cardiac output during paced tachycardia in conscious dogs.

The mechanisms of enhancement of cardiac output of unanesthetized dogs from 2.7 to 3.6 l min-1 during paced heart rate increase from 92 to 178 beats min-1 were studied in 92 trials with 5 dogs. This enhancement of cardiac output was accompanied by a 0.6 mm Hg fall in right atrial pressure and a 3.3 mm Hg fall in left ventricular end-diastolic pressure. The results are compatible with the hypothesis that an isolated rise in cardiac function shifts blood from the heart and lungs into the systemic circulation which increases the degree of filling of the peripheral vessels and hence increases mean systemic pressure. We postulate that decompression of both atria reflexly raises the tone of the peripheral vessels while the increase in arterial blood pressure reflexly lowers the tone. Apparently a balance is achieved that results in an elevated mean systemic pressure, displacement of the venous return curve to the right, and an increase in the amount of venous return that matches the enhanced cardiac output.

Animals↗
PubMed2003

Pathological changes of the myocardium in patients after atrial repair for transposition of the great arteries: a possible explanation for left ventricular dysfunction after secondary arterial switch.

BACKGROUND: Patients with transposition of the great arteries who underwent an atrial repair in infancy are likely to develop right ventricular dysfunction later in life. For these patients a two-stage arterial switch operation has been advocated by some groups but mortality even from the initial pulmonary banding procedure for retraining the left ventricle has been reported to be considerable. We asked whether pathological alterations of the left ventricular myocardium could explain for the failure of the left ventricle observed in patients after two-stage arterial switch operations. METHODS: Twelve patients aged 16.9 [8-25.4] years (median [range]) with transposition of the great arteries after atrial repair in infancy were enrolled. Median follow-up interval was 15.8 [7.8-22.1] years. Measurements of right and left ventricular systolic function were performed by echocardiography. In addition all patients underwent cardiac catheterization. Endomyocardial biopsies were taken from the right and left ventricle and examined histopathologically. RESULTS: Two out of twelve patients showed mildly reduced systolic right ventricular function. Systolic function of the left ventricle was normal in all patients on echocardiography but six out of twelve patients showed clusters of fibrous and fatty degeneration on biopsy specimens obtained from the left ventricle. CONCLUSION: We conclude that degenerative left ventricular myocardial changes could serve as an explanation for left ventricular failing when retraining the left ventricle during two-stage arterial switch operations.

Adolescent↗
PubMed2000

Positive inotropy mediated via CGRP receptors in isolated human myocardial trabeculae.

Isometric contractile force were studied on isolated human myocardial trabeculae that were paced at 1.0 Hz in tissue baths. Alpha calcitonin gene-related peptide (alpha-CGRP) had a potent positive inotropic effect in most trabeculae from both the right atrium and left ventricle, and this effect was partially antagonized by the CGRP(1) receptor antagonist alpha-CGRP-(8-37) (10(-6) M). Amylin and the CGRP(2) receptor agonist [Cys(acetylmethoxy)(2, 7)]CGRP had a positive inotropic effect in some trabeculae, whereas adrenomedullin had no inotropic effect. Using reverse transcriptase-polymerase chain reaction (PCR) mRNAs encoding the human calcitonin receptor-like receptor and the receptor associated modifying proteins (RAMPs) RAMP1, RAMP2, and RAMP3 were detected in human myocardial trabeculae from both the right atrium and left ventricle. In conclusion, functional CGRP(1) and CGRP(2) receptors may mediate a positive inotropic effect at both the atrial and ventricular level of the human heart. mRNAs for calcitonin receptor-like receptor and specific RAMPs further support the presence of CGRP receptors.

Adrenomedullin↗
PubMed2002

Prevention of atrial fibrillation by inter-atrial septum pacing guided by electrophysiological testing, in patients with delayed interatrial conduction.

AIMS: Interatrial septum (IAS) pacing seems efficient in synchronizing atrial depolarization in patients (pts) with delayed inter-atrial conduction, but its clinical role in preventing atrial tachyarrhythmias is still debated. This study was conducted in order to evaluate the clinical efficacy of IAS pacing guided by pace mapping of the IAS, as an alternative treatment modality in pts with drug refractory paroxysmal atrial fibrillation (PAF). METHODS AND RESULTS: We evaluated 29 pts (13 male, 16 female, 60 +/- 11 years), with drug refractory PAF, normal sinus node function and prolonged inter-atrial conduction time (P wave 142 +/- 10 ms). Multipolar catheters were inserted and the electrograms from the high right atrium (HRA) and proximal, middle and distal coronary sinus (CS) were recorded. The IAS was paced from multiple sites. The site of IAS where the timing between HRA and distal CS was <20 ms was considered the most suitable for synchronizing the atria. This site was found to be superior to the CS os. near the fossa ovalis in all pts. An active fixation atrial lead was positioned at this site and a standard lead was placed in the right ventricle. During IAS pacing, the P wave duration decreased significantly to 107 +/- 15 ms (P<0.001). At implant, the atrial sensing was 2.3 +/- 0.7 mV, the atrial pacing threshold was 0.95 +/- 0.15 V (0.5 ms) and the impedance was 760 +/- 80 Ohm. We evaluated the pts during four periods of 3 months duration each. The first period (control) was before pacemaker implantation, while the pts were under antiarrhythmic treatment. During the subsequent two periods, we evaluated the clinical efficacy of IAS pacing to prevent PAF recurrences, in AAT (75 bpm) and AAIR (75-140 bpm) mode, with random selection of the order and after discontinuation of antiarrhythmic treatment. During the fourth period, the same AAIR mode was assessed, but antiarrhythmic drugs were also administered. We compared the arrhythmia free interval among the four periods. The proportion of atrial paced beats in AAIR pacing mode plus antiarrhythmics was significantly higher compared with the drug-free period in AAIR mode (57 +/- 9% and 49 +/- 9% respectively, P=0017) and with AAT pacing mode (44 +/- 10%,(, P<0.001). In AAT mode, the arrhythmia free interval was 24.2 +/- 5.1 days, while it was 26.2 +/- 5.7 days in AAIR mode. These intervals did not differ significantly from the pre-implantation period (24.1 +/- 6.3 days). The arrhythmia free interval in AAIR pacing in combination with antiarrhythmic drug therapy was 38.7 +/- 8.1 days and this was significantly longer than the previous periods (P<0.05). CONCLUSION: Atrial septal pacing in combination with antiarrhythmic drug therapy reduced the incidence of PAF in pts with prolonged inter-atrial conduction times. Pace mapping of the IAS is an attractive technique to assess the shortest atrial activation time between HRA and distal CS. Whether placement of the atrial lead based on the shortest HRA--distal CS time is the best place in the IAS to prevent PAF still remains to be proven.

Aged↗
PubMed1985

Right ventricular infarction, bradyarrhythmias, and cardiogenic shock: importance of atrial or atrioventricular sequential pacing.

We report two patients with inferior myocardial infarction, complicated by bradyarrhythmia, hypotension, and clinical evidence of right ventricular infarction. Conventional therapy of volume expansion and inotropic support was insufficient to maintain an adequate blood pressure. Sequential atrioventricular (AV) pacing for AV block (Case 1) or atrial pacing for junctional bradycardia (Case 2) resulted in immediate and sustained improvement in blood pressure and clinical indices of perfusion. We recommend consideration of these pacing modes in patients with inferior infarction with evidence of right ventricular infarction, bradyarrhythmia, and cardiogenic shock. The likely mechanism of improvement is by restoration of atrial transport with consequent improvement in ventricular function.

Bradycardia↗