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At least 811 records · Page 45Linked to original sources
PubMed1985

Does A-H interval accurately represent intranodal conduction time during ectopic rhythms?

In order to determine whether the A-H interval of the His bundle electrogram accurately represents the AV nodal conduction time under various conditions, His bundle and coronary sinus electrograms were recorded in isolated perfused rabbit hearts, with atrial stimulation from eight different sites. The S-A (stimulus to the A wave) interval was significantly longer, whereas the A-H interval was shorter on stimulations from the coronary sinus and the left atrium than on sinus nodal stimulation. Stimulations from the fossa ovalis and right atrial appendage did not significantly alter the A-H interval. The effective and functional refractory periods of the AV node were almost identical with stimulations from the sinus node, low right atrial appendage, low left atrial appendage or the ostium of coronary sinus. Mapping of the excitation process with microelectrodes revealed that the activation times in low interatrial septal fibers bordering the His bundle [abbreviated as AP(III)] was closest to the A wave as compared with the activation in the ostium of the coronary sinus [AP(I)] or near the AN region [AP(II)] on stimulation from both sinus nodal and coronary sinus regions. On sinus nodal stimulation, AP(III) preceded AP(I) and AP(II) but lagged behind the A wave by 6 msec, whereas AP(III) preceded the A wave by 5 msec on coronary sinus stimulation. Thus, the A-H interval may not always accurately represent the intranodal conduction time, as relative timing of atrial activation responsible for the A wave and that of invasion of the AV node by the atrial wavefront can be grossly altered by different atrial excitation patterns.

Action Potentials↗
PubMed1977

Cardiac function in total anomalous pulmonary venous return before and after surgery.

Cardiac performance was evaluated in 12 infants with isolated total anomalous pulmonary venous return. Four had significant pulmonary venous obstruction and severe pulmonary hypertension (group A). Eight had no obvious venous obstruction, and the pulmonary pressures were lower (group B). In all subjects, right ventricular end-diastolic volume was increased (197% of predicted normal) and its ejection fraction was normal. Left ventricular volume was, generally speaking, still in the normal range (87% of predicted normal); however, its ejection fraction was reduced (0.57 vs normal of 0.73) and left ventricular output was low (3.08 L/min/m2 vs normal of 3.98). Left atrial volume was consistently small (53% of predicted normal) with an appendage of normal size. The infants in group A had smaller chamber volumes/m2 BSA than those in group B. Left atrial function was abnormal, characterized by reduced reservoir function and a greater role as "conduit" from right atrium to left ventricle. Left atrial size was not found to be critical in the surgical repair of TAPVR. Cardiac function is restored to normal following surgery.

Angiocardiography↗
PubMed1977

[Hemodynamic profile of acute myocardial infarction as a function of electrocardiographic localization].

The haemodynamic profiles of 147 cases of myocardial infarction investigated within 30 hours of the clinical onset were studies in relation to the topography of the necrosis on the ECG: there were 36 inferior (I), 29 postero-inferior (PI), 22 antero-septal (AS), 38 antero-lateral (AL), 15 deep septal (DS), and 7 strictly posterior or lateral (PL). Simultaneous recordings of the diastolic pulmonary arterial pressures and the left ventricular diastolic pressures (pre-and post-a) have shown different degrees of correlation with the topographical site. The correlation found in AS, AL and I necrosis are clearer with respect to the pre-a. The PI necroses show no correlation. Graphs of left ventricular function as well as an analysis of the various other parameters show that the DS, the AL, and to a lesser extent the PI are associated with the grossest depression of left ventricular function. A study of the amplitude of the "a" wave also shows that the effect of infacts of the free wall of the left ventricule on the compliance is greater. A study of right ventricular function as well as the correlations between the pulmonary and right atrial pressures confirms the presence of right ventricular disfunction in DS and PI necroses. Impaired left ventricular function, impaired right ventricular function, and disorders of compliance seem to be the determining factors in changing the haemodynamics in the various ECG sites of infarction.

Acute Disease↗
PubMed1969

Studies in clinical shock and hypotension: VI. Relationship between left and right ventricular function.

Left ventricular end diastolic (LVEDP) and mean right atrial (RAP) pressures were recorded simultaneously in 30 patients with shock (14 acute myocardial infarction, 10 acute pulmonary embolism or severe bronchopulmonary disease, and 6 sepsis). Myocardial infarction was characterized by a predominant increase in LVEDP, pulmonary disease by a predominant increase in RAP, and sepsis by a normal relationship between LVEDP and RAP. In all three groups a significant positive correlation was noted between RAP and LVEDP, with the regression line in cor pulmonale deviated significantly toward the RAP axis and the regression line in myocardial infarction exhibiting a zero RAP intercept at an elevated LVEDP.Low cardiac outputs with elevated LVEDP in myocardial infarction indicated severe left ventricular failure. Low outputs with elevated RAP in cor pulmonale were consistent with right ventricular overload. Although cardiac outputs often were normal in sepsis, low outputs with elevated cardiac filling pressures in some patients were consistent with a hemodynamic or humoral-induced generalized depression of cardiac performance.Vasoconstrictor and inotropic drugs often produced a functional disparity between the two ventricles, with the gradient between LVEDP and RAP increasing, apparently because of an increase in left ventricular work or an inadequacy of left ventricular oxygen delivery. Acute plasma volume expansion with dextran in patients with pulmonary vascular disease resulted in a somewhat more rapid rise in RAP than in LVEDP. In septic and myocardial infarction shock, however, LVEDP and RAP usually rose proportionally, with the absolute rise of LVEDP surpassing that of RAP. Although the absolute level of the central venous pressure thus may not be a reliable indicator of left ventricular function in shock, changes in venous pressure during acute plasma volume expansion should serve as a fairly safe guide to changes in LVEDP.

Journal Article↗
PubMed1980

[Paroxysmal sinoatrial tachycardia. Apropos of 44 cases].

44 cases of paroxysmal sinoatrial tachycardia (PAT) due to reentry within the sinus node or between the sinus node and the atrium are reported; these tachycardias are usually quite well tolerated clinically as the rhythm is rarely faster than 140/min and they are often degraded by functional AV block. They can be triggered and terminated by one (or two) atrial stimuli, and reduced by carotid sinus massage but relapse in the short term. They often alternate with a disturbance of atrial excitability in patients who also have binodal disease. Their diagnosis implies endocavitary investigation showing sinusal anterograde atrial activation and atrial and ventricular stimulation to differentiate them from other types of paroxysmal tachycardia, especially those due to reentry involving concealed right sided Kent bundles. Studies of sinus node function by atrial extrastimulus techniques in 38 patients usually showed an isolated and prolonged Zone I followed, without a transitional plateau, by a Zone IV of sinus echos during which the tachycardia could be triggered. This type of tachycardia, without doubt as common as junctional tachycardia, may respond to treatment with Quinidine, Amiodarone, Verapamil, or beta-blockers, associated with permanent pacing in cases of binodal block.

Adult↗
PubMed2000

Patient with atrioventricular node reentrant tachycardia with eccentric retrograde left-sided activation: treatment with radiofrequency catheter ablation.

We describe a patient with supraventricular tachycardia with triple atrioventricular (AV) node pathway physiology. A discontinuous curve was present in the antegrade AV nodal function curves. During right ventricular pacing, the earliest retrograde atrial activation was recorded at the left-sided coronary sinus electrode. The retrograde ventricular-atrial interval was long and had decremental conduction. We induced a slow-slow AV node reentrant tachycardia (AVNRT) with eccentric retrograde left-sided activation. After slow pathway ablation, dual AV nodal pathway physiology was present. AVNRT with eccentric retrograde left-sided activation is relatively rare, and our findings suggest that eccentric retrograde left-sided atrial inputs consist partially of a slow pathway and disappear with slow pathway ablation.

Atrial Function, Left↗
PubMed1981

Lung volume and pleural pressure effects on ventricular function.

To investigate the changes in ventricular function that occur during continuous positive-pressure ventilation, we studied the effects of separate increases in lung volume, pleural pressure, and right ventricular afterload in 15 dogs. Isovolume increases of pleural pressure caused changes in right and left ventricular hemodynamics indistinguishable from those induced by preload reduction. Lung distension with the chest open to atmosphere caused both right and left atrial intracavitary pressures to rise as cardiac output fell, suggesting altered function of both ventricles. Raising right ventricular afterload by pulmonary artery constriction did not reproduce the hemodynamic changes observed during increases of lung volume. These data indicate that the apparent alteration of ventricular function that occurs during continuous positive-pressure ventilation is produced by the associated increase in lung volume and that a right ventricular afterload-ventricular interdependence effect is not the responsible mechanism.

Animals↗
PubMed1979

Left ventricular function in rheumatic mitral stenosis. Clinical echocardiographic study.

Echocardiography was used to examine the extent and significance of impairment in left ventricular function in 20 patients with rheumatic mitral stenosis. Indices of left ventricular performance--normalised mean rate of circumferential fibre shortening (Vcf), ejection fraction, normalised posterior wall velocity, and stroke volume were reduced. The impairment in left ventricular function was related to the degree of functional disability (NYHA), right ventricular dilatation, and left atrial enlargement. Vcf was inversely related to both the internal right ventricular diameter (r=-0.767, P less than 0.001) and the degree of left atrial enlargement (r=-0.554; P less than 0.05). The normalised velocity of the interventricular septum and the maximum systolic and diastolic endocardial velocities were also reduced. These results suggest that abnormalities in contractility of left ventricular myocardium are responsible for the impaired myocardial function in patients with mitral stenosis and that such impairment is clinically significant.

Echocardiography↗
PubMed1992

Thermodilution right ventricular ejection fraction measurement reproducibility--a study in patients undergoing coronary artery bypass graft surgery.

OBJECTIVE: To assess the effects of heart rate, right ventricular systolic performance (ejection fraction), chamber dimensions, and flow rate (cardiac index) on the reproducibility of algorithm-derived triplicate thermodilution right ventricular ejection fraction measurements. DESIGN: Prospective study; combined hemodynamic and echocardiographic clinical evaluation. SETTING: Operating room in a university hospital. PATIENTS: Twenty-one coronary artery bypass graft patients. MEASUREMENTS AND MAIN RESULTS: The right atrial delivery site was positioned by analysis of transduced pressure waveform and echocardiographic imaging of tracer agitated saline cavitations. Measurement reproducibility was quantified by determining the variation (standard deviation) within 101 triplicate thermodilution measurement sets. There was no significant relationship between measurement reproducibility and estimates of right atrial area (21.6 +/- 6.9 cm2), diameter (5.1 +/- 0.8 cm) and supero-inferior length (5.1 +/- 0.9 cm) and right ventricular maximal minor axis diastolic diameter (4.21 +/- 1.05 cm). Reproducibility was also unrelated to right ventricular end-diastolic volume index (97.9 +/- 32.7 mL/m2) and cardiac index (2.9 +/- 0.9 L/min/m2). Measurement reproducibility was directly related to mean right ventricular ejection fraction (0.39 +/- 0.14) and inversely related to heart rate (80.8 +/- 18.6 beats/min) (p < .01 and < .001, respectively). CONCLUSIONS: Thermodilution-derived right ventricular ejection fraction measurement reproducibility was unrelated to estimates of right atrial and ventricular dimensions and cardiac index. Measurement reproducibility was a direct function of right ventricular systolic performance and an indirect function of heart rate. Measurement should be interpreted with these constraints in mind.

Adult↗
PubMed1983

Electrophysiologic properties of prenalterol.

We assessed the electrophysiological properties of prenalterol, a new beta-selective agonist, in 10 patients with normal and 10 patients with delayed atrioventricular (A-V) conduction times. We evaluated sinus node function, A-V conduction times, refractory periods, atrial or ventricular arrhythmias, spontaneous or induced by the single extrastimulus technique during basal conditions, 5 minutes after a first dose of 20 micrograms/kg of prenalterol, and 5, 15 and 30 minutes after a second injection of the same dose. Prenalterol increased heart rate about 20%, with statistically significant shortening of right atrial refractory periods, A-V nodal functional and effective refractory periods and A-H interval in both groups after the first dose. In the 6 patients with sick sinus syndrome, prenalterol increased heart rate significantly and decreased maximum sinus node recovery time which reached a statistically significant value (P less than 0.05) 5 and 30 minutes after the second dose. At the highest dose, prenalterol seemed to increase the number of ventricular and/or atrial arrhythmias only in those patients with the arrhythmias before treatment. Prenalterol increases heart rate and decreases A-V node conduction times. The shortening of maximum sinus node recovery time in patients with the sick sinus syndrome, especially if confirmed after oral administration, could indicate a specific use of this drug in patients with sinus bradycardia or atrial fibrillation with a slow ventricular response.

Adrenergic beta-Agonists↗
PubMed2005

Atrial septal pacing to resynchronize atrial contraction and improve atrial transport function.

OBJECTIVES: Atrial septal pacing via a trans-septal breakthrough site within the right atrial septum can shorten global atrial activation time, resulting in significant reduction of recurrence of atrial fibrillation events. This study examined whether this pacing method will lead to resynchronization of atrial contraction and its benefit on hemodynamic function can be maintained for 24 months. METHODS: Thirty patients with atrial fibrillation and delayed atrial conduction were enrolled (17 males, 13 females, mean age 73 +/- 7 years). Trans-septal breakthrough site within the right atrial septum was identified through pacing from the dorsal left atrium. Continuous atrial septal pacing at the trans-septal breakthrough site was performed for 24 months. Time difference (TD) between right and left atrial contractions was measured during atrial septal pacing and sinus rhythm by pulse Doppler echocardiography of the trans-tricuspid (P-At) and mitral (P-Am) blood flows (TD = P-Am - P-At). RESULTS: The atrial lead was screwed near the fossa ovalis in 29 of 30 patients. Atrial septal pacing yielded significantly shorter P wave duration (101.9 +/- 10.4 vs 139.6 +/- 14.7 msec, p < 0.001), leading to significant reduction of TD in atrial contraction (-8.8 +/- 10.0 vs 29.8 +/- 13.6 msec, p < 0.001)as compared to sinus rhythm. Both shorter P wave duration and reduced TD during atrial septal pacing remained statistically significant during the follow-up period as compared to sinus rhythm. Both left atrial diameter and A to E ratio of filling waves at mitral valve were significantly decreased at 12 months and remained decreased at 24 months. CONCLUSIONS: Atrial septal pacing at the trans-septal breakthrough site can resynchronize atrial contraction and results in improved hemodynamic effects during 24 months of follow-up.

Aged↗
PubMed1988

Right atrial isolation: a new surgical treatment for supraventricular tachycardia. I. Surgical technique and electrophysiologic effects.

This study describes the surgical technique and electrophysiologic effects of isolating the right atrium while preserving normal function and continuity of the sinoatrial node with the remainder of the heart. Thirteen adult mongrel dogs underwent normothermic cardiopulmonary bypass. A posterorlateral right atriotomy was performed that encircled the upper right atrium but excluded the atrial pacemaker complex. The incision was extended anteromedially to the tricuspid valve anulus just anterior to the membranous interatrial septum and inferiorly just posterior to the os of the coronary sinus and the tricuspid valve anulus. Postoperatively, electrophysiologic data confirmed (1) that the body of the right atrium was electrically isolated from the remainder of the heart, (2) that the sinoatrial node continued to function normally, and (3) that the sinoatrial node remained in continuity with the left atrium and ventricles. Right atrial tachycardia was simulated by rapid right atrial pacing and was confined to the isolated right atrium. Moreover, the simulated tachycardia did not affect normal sinus rhythm or normal atrioventricular conduction. It is concluded that isolation of the right atrium with preservation of normal sinoatrial node function and continuity is feasible. This technique offers an alternative to the current surgical approaches for management of refractory supraventricular tachycardias that arise in the right atrium.

Animals↗
PubMed1984

Regional differences in left ventricular response to atrial pacing in the dog: mapping of segmental function by two-dimensional echocardiography.

Two-dimensional echocardiography was applied in 10 closed-chest dogs to evaluate, in several left ventricular (LV) short-axis cross sections and subsegments, the regional contractile response to right atrial pacing. Compared with sinus rhythm (81 +/- 10 beats/min), which exhibited a moderate 7.2 +/- 12.0% (mean +/- standard deviation) base-to-apex increment in function, this gradient was significantly augmented to 34 +/- 12% by pacing at a heart rate of 180 beats/min. Measurements of wall thickening and perimeter shortening exhibited similar trends. Differences also were observed in subsegments of individual cross sections: in sinus rhythm the base-to-apex difference in function was relatively minor in the anterior and lateral aspects of the left ventricle (-9.1 +/- 18% and -1.9 +/- 19%), whereas a significant increase was noted in posterior and midseptal zones (18 +/- 17% and 22 +/- 30%). In response to pacing, the anterior and lateral wall base-to-apex gradients were significantly augmented (25 +/- 8% and 35 +/- 34%), but there was no further change in the posterior or septal regions. In conclusion, apical regions of the canine left ventricle responded to right atrial pacing with significant augmentation of contractile function, whereas more basal levels showed little response. Circumferentially, response to atrial pacing was most pronounced in the anterior and lateral segments.

Animals↗
PubMed1979

[Importance of the atrial vectorcardiogram in evaluating the myocardial functional state in ischemic heart disease].

The results of examination of 61 patients suffering from ischemic heart disease are analysed. All were subjected to catheterization of the right and left parts of the heart, left ventriculography, and selective coronarography. Some parameters of intracardiac hemodynamics, including the end diastolic pressure in the left ventricle, were determined. Atrial vectorcardiogram was recorded after I. T. Akulinichev's system (with mV = 100 mm). Comparison of the parameters of the atrial P loop of the vectorcardiogram with the findings of heart catheterization showed a direct dependence between the atrial changes recorded on the vectorcardiogram and the value of the left ventricular end diastolic pressure. Signs of overexertion of the left atrium grow with an increase in the end diastolic pressure. Quantitative dependence between these parameters is demonstrated. When the end diastolic pressure grows higher, overexertion of the left atrium is naturally joined by overexertion of the right atrium. Atrial vectorcardiography may be an important invasive method for appraising the functional condition of the left ventricular myocardium in patients with ischemic heart disease.

Adult↗
PubMed2005

Surgical management of Ebstein's anomaly in the adult.

Ebstein's anomaly is a rare cardiac malformation that affects the tricuspid valve, right ventricle, and right atrioventricular junction. These anatomical and functional abnormalities cause important tricuspid regurgitation that results in right atrial and right ventricular dilatation and atrial and ventricular arrhythmias. Diagnosis is made by echocardiography. Operation includes tricuspid valve repair or replacement, closure of any interatrial communications, and appropriate antiarrhythmia procedures. Repair of Ebstein's anomaly eliminates right-to-left intracardiac shunting, improves exercise tolerance and functional class, and reduces supraventricular arrhythmias. In addition, quality of life and longevity are improved.

Adult↗
PubMed1986

[Left ventricular function during atrial fibrillation assessed by left ventricular function curve using ECG-gated blood pool scintigraphy].

Cardiac function is difficult to assess in patients with atrial fibrillation due to the widely fluctuating cycle lengths resulting in variable ventricular hemodynamics. With respect to ECG-gated blood pool scintigraphy, distortion of the time activity curve occurs due to a summation of irregular cycle lengths. Therefore, performing such a study has been regarded meaningless. To evaluate left ventricular function during atrial fibrillation using scintigraphic technique, a new processing algorithm was devised to make multiple gated images which are discriminated by the preceding R-R interval, and left ventricular filling and function curves were established. The left ventricular filling curve, obtained by plotting end-diastolic volume against the preceding R-R intervals demonstrated an impairment of blood filling in cases of mitral stenosis and constrictive pericarditis, which resolved after mitral commissurotomy in case of mitral stenosis. The left ventricular function curve, established by plotting stroke volume against end-diastolic volume, was analyzed according to indices such as "slope" and "position". Both of these indices were significantly reduced in relation to the severity of heart failure according to the NYHA's functional classification and cardiomegaly on chest radiography. On individual comparisons of underlying diseases, the indices decreased in the following order; lone atrial fibrillation, hyperthyroidism, aging, hypertension, mitral valve disease, ischemic heart disease, dilated cardiomyopathy and aortic regurgitation. The indices correlated closely with ejection fraction. In cases of mitral regurgitation, however, the function curves were situated to the right and above those of lone atrial fibrillation and decreased in slope despite the fairly well-maintained ejection fraction. After treatment with digitalis and/or diuretics, the function curves shifted to the left and upward. In conclusion, left ventricular filling and function curves based on a newly-devised algorithm of ECG-gated blood pool scintigraphy are of considerable clinical value in evaluating cardiac performance in patients with atrial fibrillation. They are widely applicable to the assessment of therapeutic and interventional effects.

Atrial Fibrillation↗