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PubMed1990

Modulation of electrophysiological properties of neonatal canine heart by tonic parasympathetic stimulation.

The effects of tonic right and left vagal stimulation (RVS and LVS) on electrophysiological properties of the immature myocardium and specialized conduction system were evaluated in 11 neonatal canines pretreated with propranolol (1 mg/kg iv). Electrophysiological studies were performed by recording intracardiac electrograms from multiple endocardial catheters during programmed electrical stimulation. Assessments were made of sinus node function, intra-atrial, atrioventricular (AV) nodal and His-Purkinje conduction, and atrial and ventricular refractoriness in the control state and during RVS and LVS at 4-12 Hz. Vagal stimulation prolonged the sinus cycle length; RVS produced a 38% increase and LVS a 25% increase at 8 Hz (P less than 0.01). There were no changes in the intra-atrial or His-Purkinje conduction times. Comparable increases occurred during RVS and LVS in the paced cycle length resulting in AV nodal Wenckebach, the AV nodal conduction time at a paced cycle length of 340 ms, and the effective and functional refractory periods of the AV node, suggesting symmetrical influences of the right and left vagus on neonatal AV nodal function. Right atrial effective and functional refractory periods shortened significantly during vagal stimulation (ERP, 36% RVS and 23% LVS; FRP, 27% RVS and 15% LVS), and in 5 of 11 neonates, a sustained regular atrial tachyarrhythmia was induced during atrial extra-stimulation. Small yet significant increases were observed in the right ventricular ERP and FRP during vagal stimulation. This study provides information regarding the functional integrity of the parasympathetic nervous system and its potential role as a modulator of the electrophysiological properties of the newborn heart.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1996

Atrial reservoir and active transport function after cardioversion of chronic atrial fibrillation.

Atrial reservoir function has not been studied after successful cardioversion of chronic atrial fibrillation. Using transthoracic and transesophageal Doppler echocardiography, we measured flow velocity-time integrals of the systolic forward (Sa), diastolic forward (Da), and diastolic reversed (rAa) waves of flow velocity waveforms in the pulmonary vein and the superior vena cava, and those of the early diastolic (Ea) and late diastolic (Aa) waves of the transmitral and transtricuspid flow velocity waveforms. The left and right atrial storage fractions (LASF, RASF), indexes of atrial reservoir function, were determined as the ratios of the atrial storage volume to the ventricular stroke volume; (Sa - rAa)/(Sa - rAa + Da). The left and right atrial active contraction fractions (LAACF, RAACF), indexes of atrial active transport function, were also determined as the ratios of the atrial active contraction volume to the left ventricular stroke volume; Aa/(Ea + Aa). These indices were evaluated periodically in 12 patients with non-valvular chronic atrial fibrillation before and 1-4 days after direct current cardioversion of atrial fibrillation; in 8 of the patients, the indices were also evaluated 1-3 months after the cardioversion. An additional 10 patients in sinus rhythm served as controls. Both the LASF and RASF were low during atrial fibrillation; the values increased significantly 14 days after successful cardioversion (P < 0.01 P < 0.01), and continued to increase at 1-3 months. The LASF and RASF values 1-3 months after cardioversion were comparable to those in control subjects. Both the LAACF and RAACF also increased significantly from 1-4 days to 1-3 months after cardioversion (P < 0.05, P < 0.01), becoming comparable to those in control subjects. During the 3 months after successful cardioversion of non-valvular chronic atrial fibrillation, left and right atrial reservoir function and left and right atrial active transport function increased progressively, becoming comparable to values in the control subjects.

Aged↗

PubMed1987

Left ventricular geometry and function in adults with Ebstein's anomaly of the tricuspid valve.

We postulated that the abnormal shape, size, and function of the right heart and adjoining ventricular septum in adults with Ebstein's anomaly of the tricuspid valve might in turn alter the shape and function of the left ventricle. Seven adult patients with uncomplicated Ebstein's anomaly were studied. Left ventricular geometry was determined by two-dimensional echocardiography. Left ventricular function was assessed by treadmill exercise and radionuclide angiography at rest and with exercise. Paradoxic ventricular septal motion was consistently present. Left ventricular eccentricity (ratio of two minor axes in the short-axis view) was uniformly abnormal, averaging 1.35 +/- 0.23 (normal = 1.02 +/- 0.05). The ratio of right to left ventricular cavity size averaged 1.70 +/- 0.44 (normal 0.65 +/- 0.30), and tricuspid valve displacement into the right ventricular cavity averaged 52% (normal 8%). Functional right atrial size averaged 27.6 +/- 5.2 cm2 (normal right atrial area = 13.1 +/- 2.2 cm2). Resting left ventricular ejection fractions were below 50% in all but two patients. In response to Bruce protocol exercise stress, there were consistently appropriate increments in heart rate, blood pressure, and peak double product and, with one exception, radionuclide left ventricular ejection fraction. There were significant correlations between tricuspid valve displacement and functional right atrial size versus resting left ventricular ejection fraction and left ventricular eccentricity. These data support the hypothesis that derangements in right heart morphology and function in Ebstein's anomaly contribute to significant alterations in left ventricular geometry, but the geometric alterations are associated with tangible but less significant changes in left ventricular systolic function.

Adolescent↗

PubMed1996

Surgery for atrial fibrillation.

OBJECTIVE: The mechanisms of atrial fibrillation arc multiple reentry circuits spinning around the atrial surface, and these baffle any attempt to direct surgical interruption. The purpose of this article is to report the surgical experience in the treatment of isolated and concomitant atrial fibrillation at the Cardiac Surgical Institute of the University of Pavia. METHODS: In cases of atrial fibrillation secondary to mitral/valve disease, surgical isolation of the left atrium at the time of mitral valve surgery can prevent atrial fibrillation from involving the right atrium, which can exert its diastolic pump function on the right ventricle. Left atrial isolation was performed on 205 patients at the time of mitral valve surgery. Atrial partitioning ("maze operation") creates straight and blind atrial alleys so that non-recentry circuits can take place. Five patients underwent this procedure. In eight-cases of atrial fibrillation secondary to atrial septal defect, the adult patients with atrial septal defect and chronic or paroxysmal atrial fibrillation underwent surgical isolation of the right atrium associated which surgical correction of the defect, in order to let sinus rhythm govern the left atrium and the ventricles. "Lone" atrial fibrillation occurs in hearts with no detectable organic disease. Bi-atrial isolation with creation of an atrial septal internodal "corridor" was performed on 14 patients. RESULTS: In cases of atrial fibrillation secondary to mitral valve disease, left atrial isolation was performed on 205 patients at the time of mitral valve surgery with an overall sinus rhythm recovery of 44%. In the same period, sinus rhythm was recovered and persisted in only 19% of 252 patients who underwent mitral valve replacement along (P < 0.001). Sinus rhythm was less likely to recover in patients with right atriomegaly requiring tricuspid valve annuloplasty: 59% vs 84% (P < 0.001). Restoration of the right atrial function raised the cardiac index from 2.25 +/- 0.55 1/min per m2 during atrial fibrillation to 2.54 +/- 0.58 1/min per m2, with a mean percentage increase in cardiac index of 13.5% (P < 0.00018). Atrial partitioning ("maze operation") was performed on five patients with an immediate sinus rhythm recovery of 100%, but with two patients requiring pacemaker implant. Seven out of eight patients (87.5%), with atrial fibrillation secondary to atrial septal defect, who underwent surgical isolation of the right atrium at the time of surgery were free from atrial fibrillation and without medications. 2-52 months after operation. Thirteen of 14 patients with "lone" atrial fibrillation who underwent corridor procedure remained in sinus rhythm with a sinus rhythm recovery rate of 92%. CONCLUSIONS: Different surgical options can be chosen for different cases of atrial fibrillation, according to the underlying cardiac disease.

Adult↗

PubMed1981

Experimental evaluation of atrial function in right atrium--pulmonary artery conduit operation for tricuspid atresia.

Right ventricular bypass operations were performed in dogs by right atrium--pulmonary artery (RA-PA) conduits with closure of the tricuspid valve. Atrial fibrillation (AF) was induced in prebypass (control) and postbypass (postconduit) studies. Six dogs tolerated the procedure and had postoperative sinus rhythm (SR). In the postconduit studies, AF resulted in significant decline in both mean arterial pressure (73 +/- 2 to 65 +/- 2 mm Hg [mean +/- SEM], p less than 0.05) and pulmonary blood flow (1,050 +/- 160 to 880 +/- 110 ml/min, p less than 0.05). However, there were no significant differences between the magnitude of these changes and those during control studies. Mean right atrial pressure was markedly elevated (17.3 +/- 1.3 mm Hg) during SR after the conduit operations, but it did not increase significantly with AF. In volume load studies, pulmonary blood flow increased in proportion to rises between 15 and 30 mm Hg in mean right atrial pressure. The results suggest that right atrial contraction is not critical to the maintenance of pulmonary blood flow following RA-PA conduit operations.

Animals↗

PubMed1991

Assessment of superior vena caval blood flow velocity in ischemic heart disease.

In order to evaluate the right atrial function in patients with ischemic heart-disease, we studied the superior vena caval blood flow velocity using pulsed Doppler echocardiography. The subjects included 31 patients with anteroseptal infarction (ANT), 23 with inferior or inferoposterior infarction (INF + POS), 27 with effort angina pectoris (EAP) and 15 with vasospastic angina pectoris (VAP). The systolic peak flow velocity (PFVs) was significantly reduced only in INF + POS compared with those in ANT, EAP and VAP (36.8 +/- 1.8 cm/sec vs 46.9 +/- 2.1 cm/sec, 46.4 +/- 2.1 cm/sec and 42.6 +/- 1.9 cm/sec, p less than 0.05, respectively). No significant difference in diastolic peak flow velocity (PFVd) was found between the 4 groups. PFVs/PFVd was significantly reduced only in INF + POS compared with those in ANT, EAP, and VAP (1.39 +/- 0.05 vs. 1.75 +/- 0.08, 1.76 +/- 0.09, and 1.62 +/- 0.09, p less than 0.05, respectively). These results suggested that INF + POS caused impairment of the right atrial reservoir function.

Analysis of Variance↗

PubMed1985

[Analysis of right atrium function in patients with chronic pressure overload of the right ventricle].

Right atrial function was evaluated in 16 patients with and without chronic right ventricular pressure overload. A simultaneous right atrial pressure recording using a catheter-tip-micromanometer and right atrial volume determination using cross-sectional echocardiography were performed. The pressure-volume curve of the right atrium was composed of an a-loop and a v-loop. The ratio of active atrial emptying to right ventricular stroke volume in patients with right ventricular pressure overload was significantly larger than in the control group (36 +/- 6% vs. 23 +/- 5%, p less than 0.04). The right atrial work was also significantly greater in patients with right ventricular pressure overload (6.2 +/- 2.0 mWs) than in normal subjects (4.2 +/- 2.0 mWs, p less than 0.04). The ratio of active atrial emptying to ventricular stroke volume and right atrial work were significantly related in both control group and patients with right ventricular pressure overload (r = 0.83). Right atrial work also showed a significant linear correlation with right atrial work before active atrial emptying (r = 0.92). We conclude that in patients with right ventricular pressure overload the right atrium shows more pronounced active emptying and contributes to better diastolic filling of the right ventricle.

Angina Pectoris, Variant↗

PubMed1998

Right ventricular function in orthotopic total atrioventricular heart transplantation.

BACKGROUND: Total orthotopic heart transplantation was recently introduced into clinical practice as an alternative technique of orthotopic heart transplantation, adding bicaval and left and right pulmonary vein anastomoses to pulmonary artery and ascending aorta connection (total technique). The conventional technique (ventricular transplantation with atrioplasty) is compared with the total technique with particular emphasis on right ventricular performance. METHODS: Forty-eight mongrel dogs (23 to 31 kg) were used for 12 total and 12 standard orthotopic heart transplantations. Right ventricular (RV) function and atrial systole were analyzed with the use of micromanometry, sonomicrometry, and ultrasonic flow probes (preload-independent RV recruitable stroke work, RVPRSW). Fourier analysis was used to calculate RV power and pulmonary vascular impedance. RESULTS: There was no significant difference in cardiac ischemic and bypass times between the two groups. After transplantation, sinus rhythm was preserved after all total transplantations and after only one standard transplantation; no significant hemodynamic differences were observed. RVPRSW in the total group was conserved after transplantation; however, RVPRSW decreased by 39% (+/-8, p < .05) in the standard group. There was also a significant decrease in the rate of RV filling in the standard group after transplantation, suggesting decreased right atrial function. Pulmonary vascular impedance and RV power output were not significantly different after transplantation between the two groups. CONCLUSIONS: Total atrioventricular transplantation is a feasible alternative and conserves normal sinus rhythm. Ischemic and bypass times were not significantly different when the superior vena cava anastomosis is performed last after the release of the aortic cross-clamp. The insignificant decrease in the rate of RV filling with the use of the total technique suggests conserved RV diastolic function after transplantation with less decreased RV function in the total group.

Animals↗

PubMed1997

Serial evaluation of atrial function by Doppler echocardiography after the maze procedure for chronic atrial fibrillation.

The primary goal of the maze procedure is to prevent thromboembolism by restoring atrial function. We used Doppler echocardiography to evaluate the atrial function of patients who had undergone the maze procedure for the treatment of chronic atrial fibrillation. Thirty-five patients who converted to sinus rhythm after the maze procedure were enrolled in this study. Doppler echocardiography was performed in all patients in the early (mean, 19 days) and late (mean, 245 days) phases of the postoperative period. Left and right atrial active contraction fractions and left and right atrial storage fractions were calculated. The relationship between the pre-operative left atrial dimension and the left atrial active contraction fraction was evaluated in the late postoperative phase. The left atrial active contraction fraction was significantly increased in the late phase, but there was no change in the left atrial storage fraction. While the right atrial storage fraction was improved in the late phase, the right atrial active contraction fraction was increased even in the early phase. In patients with non-rheumatic mitral valve disease, a significant negative correlation was observed between the pre-operative left atrial dimension and the left atrial active contraction fraction in the late postoperative phase (r = 0.61; P < 0.05). However, no correlation between these parameters was observed in patients with rheumatic mitral valve disease. Atrial function was improved after the maze procedure. Serial difference were observed between left and right atrial function during recovery. Thus, in patients with non-rheumatic mitral valve disease, the left atrial dimension prior to the maze procedure may be useful in predicting the atrial contractile function postoperatively.

Atrial Fibrillation↗

PubMed2002

Factors associated with the development of atrial fibrillation in COPD patients: the role of P-wave dispersion.

BACKGROUND: Supraventricular tachyarrhythmia is a common problem in chronic obstructive pulmonary disease (COPD) patients. The purpose of this study is to analyze the factors associated with paroxysmal atrial fibrillation (AF) in COPD patients. METHODS: Forty COPD patients (38 male, 2 female, mean age 60 +/- 9 years) and 33 healthy controls (29 male, 4 female, mean age: 58 +/- 10 years) were included in this study. Echocardiography, 24-hour ambulatory and 12-lead ECG, pulmonary function tests, arterial blood gases, and serum electrolytes were measured. On ECG, maximum (P(max)) and minimum (P(min)) duration of P wave and its difference, P-wave dispersion (PWd), were measured. RESULTS: On echocardiography, diastolic dysfunction was found in 14 of the 40 (35%) COPD patients. Heart rate variability analysis revealed that COPD patients had decreased SDANN, SDNN, SDNNIDX in time-domain, and decreased LF in frequency domain parameters. Fourteen of the 40 COPD patients (35%) had AF. Patients with AF were older (57 +/- 10 vs 64 +/- 5 years, P = 0.03) and had lower SDANN, SDNN, and LF/HF ratio as compared to patients without AF in univariate analysis. All P-wave intervals (P(max), P(min,) and PWd) were increased in COPD patients compared to controls. P-wave dispersion was significantly increased in COPD patients with AF, as compared to patients without AF (57 +/- 11 vs 44 +/- 7 ms, P = 0.001). In logistic regression analysis PWd was found to be the only factor associated with the development of AF (P = 0.04). CONCLUSIONS: The presence of AF was significantly related to the prolongation of PWd, but not with pulmonary function, arterial blood gasses, and left and right atrial function.

Age Distribution↗

PubMed1998

Estimation of Right Atrial Volume and Function by an Online Echocardiographic Edge Detection System.

To define the accuracy of real-time two-dimensional echocardiographic imaging with automatic border detection (ABD) for the assessment of right atrial volume and function, we studied with ABD echocardiography 29 healthy subjects and 43 patients with sinus rhythm and various forms of heart disease. Twenty-three patients had right ventricular (RV) dysfunction (fractional area change < 45%), and 20 had RV hypertrophy from pressure overload. Doppler color flow imaging disclosed moderate-to-severe tricuspid regurgitation (TR) in 20 patients and trivial or no TR in 23. The ABD-derived end-diastolic (EDV) and end-systolic (ESV) volumes by the method of discs were used to compute fractional indexes of right atrial (RA) volume changes. Right atrial emptying fraction (RAEF) percent [(ESV - EDV)/ESV x 100] was calculated. The ABD-derived EDV and ESV correlated well with conventional offline measurements of two-dimensional echocardiographic images in the 43 patients (r = 0.94 for the end-diastolic values; r = 0.93 for the end-systolic values). Intraobserver and interobserver variability showed a high correlation between different measurements (r = 0.97 and 0.90, respectively). RA volumes were significantly higher in the patient population than in the control subjects (148.9 +/- 66.7 ml vs 43.1 +/- 9.2 ml, P < 0.0001). The right atrial emptying fraction (RAEF) was higher in patients with RV pressure overload than in normal subjects (61% +/- 11% vs 46% +/- 9%, P < 0.05) and lower in those with RV dysfunction than in the control subjects (29% +/- 7% vs 46% +/- 9%, P < 0.01). In both groups (RV pressure overload and RV dysfunction), RAEF was higher in patients without or with trivial TR compared with those with significant TR (29% +/- 7% vs 23% +/- 6%; 61% +/- 11% vs 42% +/- 7%; P < 0.05). Thus, changes in right atrial volume and function can be measured noninvasively by the ABD method. This imaging technique may prove to be useful for assessing right atrial size and function under different physiological and pathological conditions and for identifying factors that influence atrial function in right ventricular diseases.

Journal Article↗

PubMedDate not supplied

Assessment of right atrial (RA) and right ventricular (RV) function by gated blood pool scan with krypton-81m: RA and RV pressure-volume loops with simultaneous pressure data.

We developed a new method of analyzing right atrial (RA) and right ventricular (RV) function by Krypton-81m gated blood pool scan (Kr-81m-GBPS). Pressure data were recorded simultaneously with a modified Swan-Ganz catheter. Krypton-81m (Kr-81m) is ideally suited to hemodynamic study of the right heart because of the following characteristics: physical half-life of 13 seconds; high photon yield and gamma ray energy of 190 KeV; low radiation exposure; and deployment during exhalation when the left heart is not active. A computerized method for list mode data acquisition was developed to collect data from the gamma camera, ECG wave, and RA and RV pressure simultaneously. RA and RV volume curves were obtained by calibrating the time-activity curves with end-diastolic volumes and cardiac output. Ejection fraction (EF) was used in the calculation of volume and cardiac output (CO) was measured by the thermodilution method. From RA and RV pressure and volume curves, RA and RV pressure-volume (P-V) loops were created simultaneously and displayed on the same plane. One spanning cardiac cycle of RV beats was separated into four phases: the ventricular emptying phase, the early ventricular filling phase, equilibrium, and the late ventricular filling phase. One spanning cardiac cycle of RA beats also was separated into four phases as follows: the atrial filling phase, the early atrial emptying phase, equilibrium, and the late atrial emptying phase. P-V loops of RA and RV were shifted after sublingual nitroglycerin administration. This new method is potentially useful in the study of right heart hemodynamics.

Atrial Function, Right↗

PubMed1996

An 8 1/2-year clinical experience with surgery for atrial fibrillation.

OBJECTIVE: The authors analyzed the clinical results during the first 8 1/2 years' experience with the Maze procedure for the surgical treatment of atrial fibrillation. SUMMARY BACKGROUND DATA: Atrial fibrillation occurs in 0.4% to 2% of the general population and in approximately 10% of patients older than 60 years of age. It is associated with significant morbidity and mortality. The irregular heartbeat causes discomfort, the loss of synchronous atrioventricular contraction compromises hemodynamics and the stasis of blood flow increases the vulnerability to thromboembolism. METHODS: From September 25, 1987 to March 1, 1996, 178 patients underwent the Maze procedure. Thirty-two patients underwent the Maze-I procedure, 15 underwent the Maze-II procedure, and 118 underwent the Maze-III procedure. Patients were analyzed for recurrence of atrial flutter and atrial fibrillation between 3 months and 8 1/2 years after surgery (n = 164). Patients were analyzed for atrial transport function, sinus nodule function, and postoperative pacemaker requirements. RESULTS: Ninety-three percent of all patients were arrhythmia free without any antiarrhythmic medication. Of the remaining patients with arrhythmia recurrence, all were converted to sinus rhythm with medical therapy. All patients were documented to have atrial transport function by either direct visualization, transesophageal echocardiography, or atrioventricular versus ventricular pacing at the same rate. Ninety-eight percent had documented right atrial function, and 94% had left atrial function. Of the 107 patients in this series who were documented to have a normal sinus node preoperatively, only 1 patient required a permanent pacemaker. CONCLUSION: The Maze procedure is an effective treatment for medically refractory atrial fibrillation in properly selected patients.

Adult↗

PubMed1998

Bilateral atrial function after chemical cardioversion of atrial fibrillation with amiodarone: an echo-Doppler study.

Cardioversion of atrial fibrillation transiently increases the risk of embolism presumably by decreased atrial mechanical function. It has been suggested that a component of early dysfunction relates to the mode of cardioversion. Amiodarone is one of the drugs used to restore sinus rhythm in patients with atrial fibrillation. However, the effect of this drug on left and right atrial mechanical function after conversion to sinus rhythm is not well known. Thirty-one patients (group AF) cardioverted from atrial fibrillation with intravenous amiodarone (average dose 1 gm/day) were prospectively studied to examine the effect of this drug on recovery of left and right atrial mechanical function. These patients were compared with 17 consecutive individuals without evidence of cardiac disease who became our control group (group C). Transmitral flow velocities and echocardiographic parameters were recorded within 24 hours after cardioversion and on the seventh day in group AF and one time in group C. Left and right atrial ejection force to evaluate atrial mechanical function was defined as 0.5 x 1.06 x mitral (m) or tricuspid (t) orifice area x (m or t peak A velocity)2. If this value in group AF was more than the mean minus 1 standard deviation of control group data, atrial ejection function after cardioversion was considered normal. The two groups were similar with respect to age, sex, arterial blood pressure, heart rate, left ventricular diameters, and left ventricular ejection fraction. Left and right atrial size was higher in group AF (left: group AF, 18.1 +/- 3.9 cm2; group C, 11.3 +/- 2.5 cm2, p < 0.01; right: group AF, 14.9 +/- 3.2 cm2; group C, 11.6 +/- 2.3, p < 0.01). Measurements of right and left atrial ejection force measured within 24 hours and on day 7 in group AF were similar to that in group C (left: group C, 11.9 +/- 5.3 kdyne; AF group, 24 hours, 19.4 +/- 15.5 kdyne [NS]; AF group, day 7, 14.7 +/- 13.6 kdyne [NS]; right: group C, 3.6 +/- 1.99 kdyne; AF group, 24 hours, 4.3 +/- 3.3 kdyne [NS]; AF group, day 7, 3.5 +/- 2.9 kdyne [NS]). Therefore almost all patients undergoing cardioversion for atrial fibrillation with amiodarone recovered bilateral atrial mechanical function within 24 hours after cardioversion (26 of 31-84%-left atrial ejection force; 28 of 31-93.5%-right atrial ejection force), with normal left atrial function in 97% of patients and normal right atrial function in 100% of patients on day 7 after conversion to sinus rhythm. These findings may have significant implications on postcardioversion anticoagulation strategies.

Amiodarone↗

PubMed1981

[Electrophysiological properties of acute intravenous sotalol in man].

The electrophysiological properties of of 0,6 mg/Kg SOTALOL administered intravenously were studied in 15 subjects aged between 32 and 81 years. The following parameters were recorded: sinus rate (SR), corrected sinus node recovery time (SNRT), sinoatrial conduction time (SACT), PA interval, right atrial effective refractory period (ERP), right atrial functional refractory period (FRP), AH interval at rest, at 100 bpm, Luciani-Wenckebach point (LWP), AV node ERP and FRP, HV interval, His-Purkinje ERP, right ventricular ERP, corrected QT interval. At this dosage, intravenous SOTALOL displays two types of behaviour: --That common to the betablocker drugs: slowing SR by 16%, increasing the AV nodal conduction, increasing the AH interval at rest (5%), at 100 bpm (23%), increasing AV nodal ERP (26%) and FRP (20%), decreasing the LWP (18%). --Other properties: increasing intraatrial PA interval (3%), increasing right atrial ERP (II%), FRP (I7%), increasing right ventricular ERP (8%), increasing His-Purkinje ERP (when measurable) (about 6%), no change in corrected QT interval. At this dosage, SOTALOL exhibits electrophysiological behaviour similar to drugs in Class III (Touboul): those with a "wide electrophysiological spectrum".

Adult↗

PubMed2006

Right atrial size and function in patients with pulmonary hypertension associated with disorders of respiratory system or hypoxemia.

BACKGROUND AND AIM: Pulmonary hypertension (PH) determines various adaptive changes in right ventricular (RV) geometry which may progressively lead to hypertrophy, mechanical dysfunction and dilatation with pump failure. Right atrium (RA) is theoretically involved in this physiopathological process, but its role has never been investigated. We hypothesized that RA increases volume and function to assist RV during the chronic pressure overload exposition due to PH. METHODS: We prospectively enrolled 66 consecutive patients referred to our echolab with a diagnosis of PH [defined as pulmonary artery systolic pressure (PASP) >30 mmHg] associated with disorders of the respiratory system and/or hypoxemia and normal RV systolic function. Ejection force was taken up as index of RA systolic function and calculated according to the Manning's formula. Thirty-three healthy subjects for whom PH was definitely excluded by echoDoppler evaluation were used as controls. RESULTS: PASP was 42+/-10 and 20+/-8 mmHg in PH patients and controls, respectively; p=0.00001). In comparison with controls, PH patients exhibited higher RA volume (37+/-13 vs 32+/-13 ml, p=0.04) and RA ejection force (6.7+/-3.0 vs 3.5+/-1.8 Kdynes, p=0.00001). Both variables were positively related to PASP (r=0.23 and 0.48, p=0.02 and 0.00001, respectively). CONCLUSIONS: In patients with chronic PH, RA size and systolic function significantly increase and parallel signs of activation of the Frank-Starling mechanism in both right chambers. The magnitude of these phenomena is positively related to PASP levels.

Adaptation, Physiological↗

PubMed1991

The relationship between atrial pressure, atrial dimensions and atrial natriuretic factor during pacing tachycardia in dogs.

Acute supraventricular tachycardia is known to increase the plasma level of atrial natriuretic factor (ANF). The purpose of these experiments was to investigate if such an increase in plasma-ANF could be ascribed to changes in atrial pressure and atrial dimensions. Eight anaesthetized dogs were instrumented with atrial pressure catheters and sonomicrometers to measure left and right auricular and atrial free wall dimensions. An acute increase in atrial rate from 150 to 200 min-1 for 10 min did not change plasma-ANF or atrial haemodynamic variables. A further increase in atrial rate to 250 or 300 min-1 increased right and left atrial intracavitary pressures (P less than 0.01), both auricular diameters and right atrial free wall segment length (P less than 0.05). Left atrial free wall segment length remained unchanged. Plasma-ANF increased in all dogs (P less than 0.01). The change in plasma-ANF correlated well with changes in atrial pressures as well as with changes in atrial dimensions. These results support the hypothesis that release of ANF during acute atrial tachycardia may in part be attributed to atrial dilatation.

Animals↗

PubMed1996

Cardiovascular, renal, and endocrine responses to graded volume expansion in lambs during maturation.

To further investigate the maturation of the cardiopulmonary baroreflex, we measured the effects of a 45-min blood volume expansion to an increase in right atrial pressure of approximately 4 mmHg in chronically instrumented newborn (n = 17) and older lambs (n = 14). Measurements included various parameters of endocrine, cardiovascular, and renal function and concomitant recording of renal sympathetic nerve activity (RSNA). During blood volume expansion, RSNA was inhibited to a similar extent in newborns and older lambs when atrial pressures were increased by approximately 4 mmHg. A sympathoinhibition persisted in newborns but was only transient in older lambs. In newborn lambs, heart rate decreased in response to blood volume expansion, whereas heart rate remained constant after blood volume expansion in older lambs. The renal and endocrine responses to blood volume expansion were, however, similar in newborns and older lambs. These data provide evidence that when atrial pressures are matched, the renal and endocrine responses to blood volume expansion are similar, but there are differential cardiovascular and RSNA responses. Any reduced ability of the newborn kidney to excrete a volume load is therefore probably related to maturational differences in its distribution between the capacitance vessels and the heart.

Aging↗