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PubMed2006

Adverse effects of atrioventricular synchronous right ventricular pacing on left ventricular sympathetic activity, efficiency, and hemodynamic status.

Right ventricular (RV) pacing is now recognized to play a role in the development of heart failure in patients with and without underlying left ventricular (LV) dysfunction. We used the cardiac norepinephrine spillover method to test the hypothesis that RV pacing is associated with cardiac sympathetic activation. We studied 8 patients with normal LV function using temporary right atrial and ventricular pacing wires. All measurements were carried out during a fixed atrial pacing rate. The radiotracer norepinephrine spillover technique was employed to measure total body and cardiac sympathetic activity while changes in LV performance were evaluated with a high-fidelity manometer catheter. Atrioventricular synchronous RV pacing, compared with atrial pacing alone, was associated with a 65% increase in cardiac norepinephrine spillover, an increase in LV end-diastolic pressure, and a reduction in myocardial efficiency. These responses may play a role in the development of heart failure and poor outcomes that are associated with chronic RV pacing.

Aged↗
PubMed2002

The internal jugular vein valve may have a significant role in the prevention of venous reflux: evidence from live and cadaveric human subjects.

INTRODUCTION: The internal jugular vein valve (IJVV), which is situated just above the termination of the internal jugular vein, is the only valve between the heart and the brain. This means that it plays a role in the prevention of cephalad flow of venous blood. If the IJVV is damaged or becomes incompetent, increase in intrapleural pressure could result in raised intracranial pressure. Additionally, the jugular venous pulse (JVP) is used clinically to estimate right atrial pressure, a functional IJVV may prevent accurate estimation of the JVP. OBJECTIVES: To describe the presence and the competence of the IJVV in post-mortem and live human subjects. DESIGN - setting and methods: The anatomical appearance of the IJVV from 30 cadavers was studied. Competence was checked by measuring maximum hydrostatic pressure before reflux occurred through the valve. The function of the valve was evaluated in 25 live subjects using colour duplex scanning. RESULTS: The IJVV was present in all cadavers just before its termination (60 IJVVs from 30 subjects). The valve was bicuspid in most cases (93%). The competence of 41 IJVVs was checked of which only three (7%) were found to be incompetent. All IJVVs in live subjects were found to be competent. CONCLUSION: This study confirms that a functional IJVV is present just above the termination of the internal jugular vein. The IJVV may therefore prevent reflux of venous blood from the right atrium into the internal jugular vein.

Adult↗
PubMed1979

Right atrial myxoma: unusual clinical presentation and atypical glandular histology.

A 57-year-old black female presented with a 1-month of right-sided congestive heart failure and clinical evidence of pulmonic and tricuspid valvular stenosis and insufficiency. The echocardiographic examination and ventriculography demonstrated a large right atrial tumor interfering with the function of both right-sided valves. The patient underwent successful surgical resection of the tumor. Histologically, the tumor had cellular areas typical of myxoma, as well as glandular areas, a feature which has been described very rarely in this lesion. Electron microscopy of the glandular zones, which has never been reported previously, shown cells having essential homology with the usual myxoma elements. The atypical histopathology of this lesion supports the theory that atrial myxomas are true neoplasms, and are not derived from unusually organized mural thrombi.

Collagen↗
PubMed1975

Effects of atrial pacing site on atrial and atrioventricular nodal function.

The effects of the site used for atrial pacing on atrial and atrioventricular nodal conduction were assesed in 16 patients. In 13 patients, three atrial pacing sites were used: high right atrium, low lateral right atrium, and midcoronary sinus. Two recording sites were used: low septal right atrium, including His electrogram, and high right atrium. Stimulus (S) to high right atrium interval was longest with coronary sinus pacing (76 plus or minus 7 ms) (P less than 0.001), and shortes with high right atrial pacing (41 plus or minus 3 ms) (P less than 0.05). There was no significant difference in stimulus to low septal right atrium from all three pacing sites. Atrial functional and effective refractory periods were not significantly different. Mean low septal right atrium to His was significantly shorter from the coronary sinus (93 plus or minus 8 ms) (P less than 0.001), as compared to high right atrium (139 plus or minus 16 ms), and low lateral right atrium (129 plus or minus 13 ms) pacing. AV nodal functional and effective refractory periods, and the paced rate producing AV nodal Wenckebach were not significantly different when comparing the three sites. Left atrial appendage and high right atrium were similarly compared in three additional patients, and no significant differences were found in conduction times and refractory periods.

Adult↗
PubMed2005

Atrial flutter and atrial fibrillation: which relationship? New insights into the electrophysiological mechanisms and catheter ablation treatment.

Atrial fibrillation (AF) and atrial flutter (AFL) are two arrhythmias commonly associated in clinical practice. This association generally reflects a similar arrhythmogenic substrate. It has been observed that the development of isthmus-dependent AFL is often preceded by AF. The conversion from AF to AFL develops thanks to a line of functional block in the right atrial free wall. In this subset a particular condition is represented by typical AFL that occurs during the treatment with class IC or III antiarrhythmic drugs in patients with previous AF. A hybrid approach (antiarrhythmic drugs and catheter ablation) has been proposed as a possible treatment of drug-induced AFL. The conversion from AFL to AF is less frequent and may be due to several mechanisms: a shortening of the length of the line of functional block, atrial ectopic beats or rapid atrial rhythm, focal activation from the pulmonary veins, alternans of atrial action potentials. Also, atypical right and left AFL can determine AF. Finally, atypical AFL may occur after AF ablation, and could be prevented by associated cavotricuspid isthmus ablation.

Animals↗
PubMed2002

Evolution of ventricular function during permanent pacing from either right ventricular apex or outflow tract following AV-junctional ablation for atrial fibrillation.

AIMS: To compare acute and chronic ventricular function between patients, without cardiac failure, paced at either right ventricular apex or outflow tract. METHODS: Twenty patients. 10 paced apically and 10 in the outflow tract, underwent two radionuclide ventriculograms. Eight parameters of systolic or diastolic function were compared at each assessment, as were changes within each group over time. RESULTS: No differences were identified in systolic function between pacing sites 6 weeks after pacing or 23 weeks later. Peak filling rate was lower (P=0.04) at the second assessment with outflow tract pacing. No other diastolic differences were identified. Between assessments, time to peak filling rate prolonged (P=0.04) with apical pacing, while left ventricular area reduced (P=0.04) and peak filling rate decreased (P=0.04) with outflow tract pacing. Septal motion was better preserved with outflow tract pacing. No other parameter changed over time. ECG measures were similar at 14.7 months. CONCLUSIONS: No major differences were identified in systolic function between pacing sites. Some systolic parameters were better preserved with outflow tract pacing and diastolic function deteriorated subtly over time in both groups. Right ventricular pacing adversely affects left ventricular function.

Aged↗
PubMed1998

Carl J. Wiggers and the pulmonary circulation: a young man in search of excellence.

Oddly, Carl Wiggers (1883-1962), who is remembered for his work on the systemic circulation, may be considered the "American father of the pulmonary circulation." In nearly-20 papers published in the American Journal of Physiology between 1909 and 1925, he reported the first reliable pressure contours in the pulmonary artery, inquired into the relationship between respiration and pulmonary arterial pressure, examined right atrial and right ventricular function, and demonstrated how right and left heart dynamics relate to heart sounds. He also stimulated direct visualization of the lung microcirculation. Method and concept are inextricably linked in the progress of science. His contributions to the pulmonary circulation were based on his high-fidelity pressure and sound recording instruments, which he ultimately applied in the left heart. Wiggers' search for excellence in method brought him well-deserved fame in the systemic circulation, but the search began in the lung.

History, 20th Century↗
PubMed2005

Left atrium: no longer neglected.

Left atrial evaluation is strongly linked to the history of cardiac imaging. In the past, the importance of this chamber has been largely downplayed because cineangiography could not visualize it directly. Nowadays echocardiography can easily assess left and right atrial size and function. Left atrial enlargement is frequent in many cardiac diseases. A main determinant of left atrial volume is ventricular diastolic function. It has recently been suggested that left atrial volume might be the morphophysiologic expression of chronic diastolic function. In fact the left atrium is exposed directly to left ventricular diastolic pressure through the open mitral valve and because of its thin wall structure it tends to dilate with increasing pressure. Other important determinants of atrial volume are the degree of ventricular remodeling, mitral regurgitation and the presence of atrial fibrillation. The degree of left atrial enlargement is associated with adverse prognosis in different clinical settings. Patients with dilated cardiomyopathy and with a left atrial volume > 68 ml/m2 have a 3.8-fold risk compared with those with smaller left atrial volume. The predictive value of left atrial volume is independent of left ventricular systolic and diastolic function, mitral regurgitation and atrial fibrillation. This is noteworthy because these factors are both determinant of left atrial volume and have a strong impact on outcome. It might be concluded that left atrial volume represents a powerful predictive marker because it is a window allowing comprehensive evaluation of several factors associated with bad prognosis, which are often difficult to document separately.

Animals↗
PubMed1990

[Have the results of mitral valve replacement improved?].

The operative mortality following valvular surgery remains substantial for specific high risk groups despite recent improvement in surgical techniques, anesthetic managements, and postoperative care. To test the contention that the results of valvular surgery are better in recent years, we examined patients undergoing isolated or combined mitral valve replacement in an earlier era (1980-1984; n = 68) and a later era (1985-1989; n = 106). There were no significant differences concerning the clinical characteristics between an earlier era and a later era, although patients in an earlier era were more seriously in hemodynamics, and in a later era were older, a higher prevalence of reoperations and a combined tricuspid valve surgery. The operative mortality was 10.3% in an earlier era, 6.6% in a later era, and so it is not significantly improved in a recent 5 years, however the incidence of premature death (death within 30 days) except valve re-replacement was significantly improved. Using univariate multiple logistic model, the predictors for operative death after mitral valve replacement in an earlier era were advanced NYHA functional class, larger CTR, higher systolic pulmonary pressure and pulmonary capillary wedge pressure, associated preoperative organ dysfunction and heart lung machine time. In a later era, these were advanced NYHA functional class, higher right atrial mean pressure, associated preoperative organ dysfunction, valve re-replacement, heart lung machine time and aortic cross clamp time. Multivariate analysis including these significant factors could not demonstrated the most independent predictors of operative mortality after mitral valve replacement in both an earlier era and a later era.(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1985

[Dispersion of auricular refractory periods. Role of the intensity of the stimulation current].

In a series of 12 patients, the right atrial effective and functional refractory periods (ERP and FRP) were determined at 3 different sites and at 3 different intensities (threshold intensity and double and triple the threshold intensity). The mean of the range of the ERP in the same atrium was 43.4 ms and that of the FRP was 53.5 ms. These ranges appear to be independent of the intensity of stimulation. However, the values of the refractory periods were strictly correlated with the intensity of the stimulation current used. This correlation appeared to be much more marked for the ERP than for the FRP.

Electric Stimulation↗
PubMed1982

Myocardial catecholamine metabolism in patients with chronic aortic regurgitation.

In 17 patients suffering from severe chronic aortic regurgitation (AR) (New York Heart Association functional class III), right atrial biopsies were taken during aortic valve replacement. In these samples, we determined the myocardial content of norepinephrine (NE), normetanephrine (NM), epinephrine (E) and dopamine (DA). Two to 4 days before valve replacement, plasma catecholamines were measured at rest and during isometric exercise. Fifteen patients with secundum atrial septal defect (ASD) served as controls. In patients with chronic AR who had no clinical signs of cardiac failure, the myocardial content of NE (p less than 0.025), NM (p less than 0.05) and E (p less than 0.05) was significantly reduced compared with that in patients with ASD. The right atrial content of DA was not different in the two groups. All patients had normal levels of plasma catecholamines at rest. During isometric exercise, however, the increase in plasma NE was significantly higher in patients with AR than in the control group (p less than 0.005). We conclude that patients with chronic AR who have an exaggerated increase in sympathetic activity during isometric exercise probably have a decrease in myocardial NE tissue content as well. Therefore, clinical demonstration of a hyperadrenergic response during isometric exercise indicates alteration in myocardial metabolism in patients with severe chronic AR.

Adult↗
PubMed1977

[Experimental studies concerning the hemodynamic and metabolic functions in the canine heart-lung preparation supported by a donor (author's transl)].

In the usual canine heart-lung preparation the coronary blood flow does not remain constant, but increases steadily ; usually, at the moment of the set up of the preparation the coronary blood flow was about 20 ml/min/100 g heart. However, in the course of 2 approximately 3 hours it becomes more than 150 ml/min/100 g heart and the responsiveness of the coronary artery is completely lost under this condition. Concurrently with the increase in the coronary flow, cardiac functions tend to deteriorate. In order to eliminate those experimental disadvantages, we added a donor dog to the heart-lung preparation. It was found that the support by the donor dog resulted in the complete improvement of the above-mentioned deterioration ; the coronary circulation (coronary blood flow and coronary artery and sinus blood oxygen saturation), cardiac function (cardiac output, right atrial pressure, heart rate and others) and cardiac metabolism (myocardial oxygen consumption, mycardial redox potential and others) were kept constant at a favorable state for more than 10 hours.

Animals↗
PubMed2000

[Non-invasive evaluation of the hemodynamic profile in patients with heart failure: estimation of right atrial pressure].

The estimation of right atrial pressure is often needed for the diagnosis, management and monitoring of various pathologic hemodynamic conditions and plays a significant role in patients with chronic heart failure. In the past decade several attempts have been made to non-invasively estimate right atrial pressure, and echocardiography has always been considered the most reliable tool. Morphologic parameters such as respiratory motion of the inferior vena cava, its respiratory diameters and percent collapse (caval index), left hepatic vein diameter or right atrial dimension (areas, volumes) were initially studied. More recently, functional data such as left hepatic or tricuspid flow variables have been considered. Some of these indexes, however, offer only semiquantitative measures of right atrial pressure, and have failed to demonstrate any prognostic value. Others, although highly sensitive and specific, are useful only in selected groups of patients because of technical or clinical limitations. In recent years, attention has focused on Doppler diastolic tricuspid flow as a means of predicting mean right atrial pressure. Analyzing the Doppler tricuspid velocity profile and mean right atrial pressure (Swan-Ganz catheter) simultaneously recorded in patients with severe left ventricular systolic dysfunction and chronic heart failure, acceleration rate of early filling emerged as the strongest independent predictor of right atrial pressure both in patients in sinus rhythm and in those with atrial fibrillation (r = 0.98), irrespective of whether the recordings are at baseline or after acute loading manipulations.

Atrial Function, Right↗
PubMed2006

Evaluation of atrial thrombus formation and atrial appendage function in patients with pacemaker by transesophageal echocardiography.

BACKGROUND: Physiologic pacing is claimed to be superior to ventricular pacing in as much as it entails lower risk of atrial fibrillation, stroke, and atrial remodeling. There are few data on the relation between atrioventricular (AV) synchrony and atrial clot formation. Utilizing transesophageal echocardiography (TEE), this study sought to evaluate the effect of AV synchrony loss on left atrial physiology, atrial stasis, and clot formation. METHODS: We conducted a cross-sectional study on patients with both AV and ventricular pacing with left ventricular ejection fraction (LVEF) >30%. TEE enabled us to explore atrial and pacing leads thrombi and measure left atrial appendage (LAA) flow velocity. RESULTS: A total 72 patients (mean age, 65 +/- 11.7) were enrolled in the study. The pacing mode was VVI in 53% and AV sequential in 47% of patients. LVEF (mean +/- SD; %) was 53.3 +/- 6.2% in ventricular pacing mode and 52.2 +/- 6.6 in physiologic pacing mode. Thrombus formation on pacing lead (<10 mm in 97% of patients) was observed in 32% of all the patients (23% in patients with AV sequential pacing mode and 39% with VVI mode). Left atrial appendage flow velocity (LAA-FV) was significantly higher among the patients with AV sequential pacing mode (49.44 +/- 18 cm/s vs 40.94 +/- 19.4 cm/s, P value = 0.02). LAA-FV >40 cm/s was detected in 60% of the patients, 60% of whom were in physiologic mode. Left atrial size was significantly larger among the patients with VVI pacing mode (42.3 +/- 2.3 mm vs 37.79 +/- 4.5 mm, P = 0.001). Multivariate analysis showed no relation between LAA-FV and age, hypertension, diabetes mellitus, left atrial size, and left ventricular function. Only one patient had right atrial clot. There was no thrombus in the ventricles and atrial appendage. CONCLUSION: Long-term loss of AV synchrony induced by VVI pacing is associated with the impairment of LAA contraction. Thrombus formation in the LAA is not increased by VVI pacing in patients with relatively good left ventricular (LV) function and sinus rhythm.

Aged↗
PubMed1991

Morphologic-echocardiographic correlates of Ebstein's malformation.

The cross-sectional echocardiographic findings were analysed retrospectively in 26 patients with Ebstein's malformation in the light of studies of autopsied specimens from different patients showing this lesion. The salient anatomical feature in diagnosis is the finding of the hinge point of the septal and mural leaflets of the valve within the inlet component of the right ventricle rather than at the atrioventricular junction. The other important feature is the nature of the distal attachment of the leaflets, particularly the anterosuperior one, which can either be in focal or linear fashion. The hinge point of the septal leaflet was noted echocardiographically to be displaced in 19 patients but, significantly, the leaflet was absent in the other seven. Also significant was that the hinge point of the mural leaflet at the crux had been visualized in only 15 of the patients. The anterosuperior leaflet had a distal linear attachment in 20 of the patients, with the anteroseptal commissure becoming a keyhole in six of these through which blood passed to the functional right ventricle. The valve remained a competent structure, even though closing at the junction of atrialized and functional components of the right ventricle rather than at the atrioventricular junction. Cross-sectional echocardiography is the technique of choice with which to display the salient morphological features of Ebstein's malformation.

Adolescent↗
PubMed1988

Sinus node and atrioventricular nodal function in 220 patients recovering from acute myocardial infarction.

Sinus node and atriventricular (A-V) nodal functions were evaluated by right atrial pacing in 220 consecutive patients recovering from acute myocardial infarction (AMI), 10-28 days after the infarct (mean = 14 days). In the 188 patients in whom a pacing rate of 120 beats/min could be achieved, sinus node recovery time, corrected sinus node recovery time (CSNRT) and total recovery time were correlated to infarct site and the presence or absence of myocardial ischemia. Sinus node recovery time and total recovery time were significantly longer in patients with inferior (1,153 + 28 and 3,129 + 179 ms, respectively) or non-Q-wave infarct (1,112 + 28 and 3,730 + 266 ms, respectively), than in patients with anterior infarct (1,044 + 20 and 1,153 + 28 ms, respectively). The parameters were within the reported normal range. When corrected for heart rate (CSNRT), these differences were no longer present. The presence or site of residual ischemia during right atrial pacing did not affect the sinus nodes parameters. A-V nodal function, studied in all 220 patients, was assessed by the appearance of second-degree A-V block at pacing rates below 120 beats/min and by measuring the shortest atrially paced cycle length with 1:1 A-V conduction. Second-degree A-V block appeared at a similar frequency in different AMI locations. Thus, sinus and A-V node functional status in patients recovering from AMI are not affected by infarct site or by the presence or absence of residual myocardial ischemia.

Adult↗
PubMed1983

Experimental studies on sick sinus syndrome: relationship of extent of right atrial lesions to subsidiary pacemaker shift and its function.

An area where the sinus node was located in 36 dogs was defined as the "SN-area." Five to 7 days after cauterization of the SN-area, a subsidiary pacemaker remained in the SN-area in seven (group S) and shifted to outside the SN-area in 14 dogs (group E). The SN-area in group S had escaped complete destruction, but that in group E was destroyed completely. Heart rate in group S and group E was 154.0 +/- 27.1 and 107.6 +/- 16.8 beats/min (p less than 0.001), respectively. Maximum duration of asystole after overdrive (maxDAO) in group S and group E was 656.7 +/- 260.2 and 2470.2 +/- 2271.6 msec (p less than 0.01), respectively. Propranolol (0.2 mg/kg intravenously) decreased heart rate in group S and group E to 88.3 +/- 7.9 and 71.7 +/- 8.7% (p less than 0.001), and prolonged maxDAO to 140.1 +/- 28.1 and 492.7 +/- 591.4% (p less than 0.025), respectively. It is concluded that the rate and stability of subsidiary pacemakers after cauterization of the sinus node have a close relationship with their location in the right atrium, which is dependent on the extent of lesions in the SN-area. Sympathetic tone played a significant role in maintaining these functions in group E.

Animals↗