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At least 37 records · Page 2Linked to original sources
PubMed1981

Measurement of normal left atrial function with gated radionuclide angiography.

A method is described for measuring relative left atrial volume changes with gated radionuclide angiography, using an approximate computer-generated functional image to locate the atrial region of interest. M mode echocardiographic measurements of left atrial and left ventricular distances from the chest wall allowed calculation of a correction factor for the differential attenuation of atrial and ventricular photons. Background-corrected left atrial time-activity curves obtained from normal subjects exhibited excellent temporal resolution and were used to identify and quantitate the reservoir and contractile phases of left atrial volume change. In 20 normal subjects, the mean (+/- standard deviation) value for left atrial fractional emptying was 0.39 +/- 0.07. Expressed as fractions of the left ventricular stroke volume, mean values of the specific phases of atrial volume change were (1) reservoir volume 0.25 +/- 0.09, (2) contractile volume 0.29 +/- 0.10, and (3) conduit volume 0.46 +/- 0.12.

Adult↗
PubMed1992

Left atrial function in ischemic heart disease assessed by intravenous digital subtraction angiography.

To investigate changes in left atrial morphology and dimensions during the cardiac cycle, the atrium was visualized by intravenous digital subtraction angiography (DSA). The study subjects consisted of 22 male patients whose average age was 54.5 +/- 8.6 years. They had ischemic heart disease without mitral valve disease and were in sinus rhythm. They were 11 patients with old myocardial infarction (OMI group) and 11 who had chest pain without evidence of infarction (AP group). DSA was performed in the continuous mode. Contrast material (35 ml) was injected at a rate of 18 ml/sec via a catheter in the superior vena cava and subtraction images were obtained at a speed of 30 frames/sec in the right anterior oblique projection. The left atrial and left ventricular margins were traced manually, their areas were calculated, and fractional changes in area were analyzed. The left ventricular ejection fraction (LVEF) was calculated by densitometry. Cardiac catheterization was performed in 16 patients and the left ventricular end-diastolic pressure (LVEDP) and mean pulmonary arterial wedge pressure (PAWP) were measured. The entire left atrium was clearly imaged using DSA. Phase analysis of the time-area curves in the right anterior oblique projection revealed that the left atrial area was maximal during left ventricular end-systole (%LA1 = 100%), it decreased during early left ventricular diastole (%LA2), and then increased slightly again during mid-diastole (%LA3). After left atrial contraction, the minimum area was obtained (%LA4). The left atrium showed a two-stage decrease in the area due to passive emptying and active contraction during left ventricular diastole. Passive emptying (%LA1-%LA2) was significantly less in the OMI group than in the AP group (6.3 +/- 3.6 vs 13.3 +/- 4.8%, p < 0.01, respectively). In all 22 subjects, passive emptying correlated with LVEF (r = 0.70, p < 0.001) and LVEDP (r = -0.58, p < 0.05). There was no difference in active contraction (%LA3-%LA4) between the 2 groups (26.0 +/- 5.7% in the OMI group, 28.2 +/- 8.4% in the AP group), and it did not correlate with LVEF or LVEDP. The ratio of passive emptying to active contraction [(%LA1-%LA2)/(%LA3-%LA4)] correlated with LVEF (r = 0.63, p < 0.01). These findings suggested that impaired left ventricular diastolic function and a relative increase in atrial contraction were present in patients with a lower LVEF. The %LA4 correlated with LVEDP and PAWP (r = 0.65, r = 0.63, p < 0.01, respectively). In conclusion, DSA proved to be a useful method for investigating left atrial morphology and function.

Aged↗
PubMed1978

Clinical value of tests of sino-atrial function.

Sinus node recovery times and the premature atrial stimulus test were studied in 36 patients, seven with gross sinus node disease, 25 with possible sinus node disease and four with no clinical evidence of sinus node disease. The corrected sinus node recovery time proved of most value in predicting which patients needed and would benefit from permanent pacemaker implantation, though there was one false negative diagnosis and two patients with abnormal corrected sinus node recovery times were asymptomatic. The premature atrial stimulus test usually proved to be of no practical value once severe sinus node disease was present and, in the group of patients with suspected sino-atrial disease, only 13 of 25 graphs could be analysed due to gross "scatter" in the others. When patients with symptoms have unequivocal evidence of sino-atrial dysfunction, invasive study seems unnecessary. With lesser degrees of sino-atrial disease, premature atrial stimulation may provide confirmatory evidence; but when sinus arrhythmia, atrial escape beats, or more marked dysfunction are present, one is likely to encounter useless "scatter" graphs. In the absence of regular sinus rhythm on the ECG, overdrive sinus node suppression in the only invasive study worth attempting.

Adolescent↗
PubMedDate not supplied

Remnant atrial function in human and animal recipients of a total artificial heart.

The native atria remains intact after total artificial heart (TAH) implantation. The electrical activity of the recipient's atria can be recorded from wires placed during TAH implantation. Regulating TAH heart rate by coupling it with native atrial activity has the potential for a more physiologically responsive TAH. The reactivity of the atrial impulse rate is a critical component of this link, but little is known about atrial responsiveness after TAH placement. Two human and three animal TAH recipients had recordable atrial electrical activity. Human atrial impulse rate after TAH was relatively constant at rest but unresponsive to physiologic stimuli. Analysis of human atrial contraction provided no discernable effect on ventricular filling. Animal atrial impulse rate at rest was more rapid than calves without a TAH. The bovine TAH recipients had an atrial impulse rate that responded to catecholamine stimulation and blockade. Isoproterenol caused a significant rise in atrial impulse rate (152 +/- 16 impulses per minute to 216 +/- 24 impulses per minute; p < 0.05) and propranolol caused a decrease in atrial impulse rate (142 +/- 20 impulses per minute to 122 +/- 19 impulses per minute; p > 0.05). Despite beta blockade, the atrial impulse rate remained abnormally elevated secondary to unknown factors. Animal atrial contraction did appear to intermittently augment TAH ventricular filling. These data indicate that the atria remains electrically intact after TAH implantation. The human atrial impulse rate was unresponsive to physiologic stimuli although the animal atrial impulse rate was affected by exogenous catecholamine administration, but the rate remained abnormally rapid.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Significance of right atrial function during right sided inotropic stimulation of pig hearts in situ.

Cardiac adjustments to inotropic stimulation of the right side of the heart were examined in anaesthetised, open chest pigs by calcium chloride infusion (80 mumol.min-1) into the right coronary artery. At stable haemodynamic conditions and at constant heart rate, right ventricular (RV) pre-ejection segment length increased by 4.6 (2.7-7.2) % (median, 95 % confidence interval) (p less than 0.01), RV end diastolic pressure rose from 5.3 (3.4-7.7) to 6.0 (3.6-8.8) mm Hg (p less than 0.05), and stroke volume rose by 6.8 (4.2-10.8) % (p less than 0.001). When the effect of right atrial contraction on RV filling was excluded by simultaneous pacing of atria and ventricles, the RV pre-ejection segment length no longer increased, and stroke volume rose by only 3.5 (0.1-9.5) % (p less than 0.05) during right side inotropic stimulation. Right atrial inotropic stimulation improves right ventricular filling, and may cause redistribution of blood from the systemic to the pulmonary circulation. This redistribution would raise the pulmonary vascular pressures, and thereby also improve left ventricular filling. The improved right ventricular filling partly accounts for the rise in RV output.

Animals↗
PubMed1991

Renal excretory function, atrial natriuretic peptide (ANP) and plasma renin activity (PRA) during long-term sodium loading in rats.

The effect of chronic sodium loading on the level of plasma atrial natriuretic peptide (ANP) and on plasma renin activity (PRA), as well as on the renal excretory function was studied. Fifty-six standardly bred Long Evans rats were divided into three experimental groups: controls, rats drinking 170 mmol NaCl/l solution instead of water, and rats consuming food with high sodium content (850 mmol NaCl/kg) for 21 days. During the study, we measured the amount of fluid intake, the parameters of the renal function: diuresis (VU); sodium, potassium and cloride excretion (UNa V, UKV and UClV), and the dynamics of body mass. On the 21st day the animals were sacrificed by decapitation. Plasma ANP and PRA were determined radioimmunologically. Packed cells volume and plasma Na and Cl concentrations were measured. The data showed a full compensation in sodium balance: the body mass dynamics in the three groups was similar; no changes in packed cells volume and plasma electrolytes were seen; UNaV and UClV were significantly increased in the groups with high sodium intake. PRA was significantly depressed in the two groups while ANP did not show any real changes. We concluded that it is PRA and not ANP that might participate in the regulation of chronic sodium balance.

Animals↗
PubMed1978

[Evaluation of sino-atrial function using the method of extrasystole induced by constant-relative premature impulses. 2. Application in 50 normal and abnormal studies].

The total immediate sino-atrial conduction time (SACT) as calculated by constant relative pacing, 40 or 50% of the immediate sinus cycle (SC), normally varies inversely with the SC. 50 patients were investigated by this method. In 38 patients without sino-atrial block (SAB) on the surface ECG, it was found that the mean slope of correlation between SACT and SC varied with the shape of the curve of Strauss and with the presence or absence of a post-pacing depression. The smallest slope was found in the group in which the curve of Strauss was horizontal in zone II, and in which there was no depression. In the groups with a rising zone II, comparative use of pacing with a fixed relationship in milliseconds suggested a phenomenon of decreasing retrograde conduction. In cases with sinus arrhythmia and a Strauss curve with scattered coordinates, the relationship between SACT and SC was maintained. 1st degree right-sided SAB should therefore be defined as a function of the immediate SC. In 12 other patients with SAB on the surface ECG, the immediate SACT was greatly lengthened so as to be immeasurable, and bore no relationship to the SC.

Adolescent↗
PubMed1988

Bovine adrenal medullary cells contain functional atrial natriuretic peptide receptors.

The recent report that bovine adrenal chromaffin cells synthesized and secreted atrial natriuretic peptide, ANP, suggested that the peptide may have binding sites in the gland itself. Studies in bovine adrenal medulla membranes did reveal a single class of high affinity [125I]-ANP binding sites with a KD of 94 pM and a density of 1.7 pmol/mg protein. Binding was very rapid (association half-time: 2.5 min), and specific in that only unlabelled ANP displaced bound [125I]-ANP. Application of ANP to bovine chromaffin cells in culture, resulted in a concentration-dependent increase in cGMP synthesis. The data suggest the presence of biologically functional ANP receptors in adrenal chromaffin cells.

Adrenal Cortex↗
PubMed1984

Echocardiographic evaluation of atrial function after Senning and Mustard correction for transposition of the great arteries.

Two groups of six children who had undergone either Senning or Mustard repair for uncomplicated transposition of the great arteries were studied with M mode echocardiography derived from a phased array sector scanner picture. The newly created atria were visualised from the subxiphoid region and the upper systemic venous inflow was selected for a simultaneous M mode registration with a subsequent wall motion analysis with a commercially available computer. In the Mustard group of patients the atrial walls seemed to move passively with the overall heart movements, while abrupt atrial wall excursions of both atria synchronous with heart action were noted in all patients after Senning repair. In this group also slow cyclic changes followed respiration. The atrial wall movements were significantly superior (p = 0.001) in the Senning group of patients. It is concluded that, in contrast to the Mustard method, the Senning operation seems to lead to a viable atrium with the capability of increasing and diminishing atrial diameter and with subsequent potential for growth.

Adolescent↗
PubMed1976

Functionally atrialized parchment-like right ventricle with extensive myocardial fibrosis of left ventricle.

A 18-year-old female with unusual type of parchment-like right ventricle died of intractable congestive heart failure was reported. A catheter study revealed the absence of systolic contraction of the right ventricle. The pressure tracing curve in the right ventricle was virtually the same as in the right atrium. At autopsy, there was an extensive myocardial fibrosis of the left ventricle in addition to the almost total absence of the myocardium of the right ventricle. The case was considered to be a unique type of idiopathic cardiomyopathy.

Adolescent↗