Effect of right ventricular pacing on ventricular rhythm during atrial fibrillation

In 13 patients with atrial fibrillation, the effect of right ventricular pacing at various rates on spontaneous RR intervals was studied. Five hundred consecutive RR intervals were recorded and measured before and during varying right ventricular pacing rates. As anticipated, all RR intervals longer than the right ventricular pacing intervals were abolished. However, RR intervals shorter than the right ventricular pacing intervals were also eliminated. It is difficult to explain the elimination of RR intervals shorter than the pacing intervals with the accepted concepts concerning the mechanisms governing the rate and rhythm of the ventricular response to atrial fibrillation. An alternative explanation may be that during atrial fibrillation the atrioventricular node behaves as a nonprotected pacemaker that is electrotonically modulated by the chaotic atrial electrical activity. The result is a random ventricular rhythm. With right ventricular pacing, the automatic focus is depolarized by the retrogradely concealed conducted ventricular impulses, the short RR intervals are not generated as a consequence and the rhythm becomes pacemaker dependent.     

Unusual manifestations of arrhythmogenic right ventricular dysplasia as ventricular fibrillation, atrial paralysis, and hypoexcitable right ventricle

Ventricular fibrillation occurred in an apparently healthy 19 year old man. The results of non-invasive and invasive studies suggested right ventricular dysplasia. Electrophysiological studies showed atrial paralysis, hypoexcitability of multiple areas of the right ventricle, and inducible poorly tolerated ventricular tachycardia.     

Candida right ventricular mural endocarditis complicating indwelling right atrial catheter

Catheter-associated candidemia is a common problem in immunocompromised patients. A leukemic patient had Candida right ventricular mural endocarditis complicating an indwelling right atrial catheter. To our knowledge, this is the first reported case of Candida right ventricular mural vegetation visualized by two-dimensional echocardiography.     

Unusual manifestations of arrhythmogenic right ventricular dysplasia as ventricular fibrillation, atrial paralysis, and hypoexcitable right ventricle.

Ventricular fibrillation occurred in an apparently healthy 19 year old man. The results of non-invasive and invasive studies suggested right ventricular dysplasia. Electrophysiological studies showed atrial paralysis, hypoexcitability of multiple areas of the right ventricle, and inducible poorly tolerated ventricular tachycardia.     

Right atrial ischemia exacerbates hemodynamic compromise associated with experimental right ventricular dysfunction

To determine the importance of right atrial function with acute right ventricular dysfunction, sequential right ventricular and right atrial ischemia were induced in 15 dogs. Right ventricular ischemia resulted in right ventricular free wall dyskinesia, right ventricular dilation by ultrasound, elevated right ventricular filling pressure and paradoxic septal motion. There were decrements in right ventricular systolic pressure (28.9 +/- 5.5 to 25.5 +/- 4.6 mm Hg) (p less than 0.05 for these and all subsequent values) and stroke work (5.66 +/- 0.94 to 2.66 +/- 0.62 g.m/m2), resulting in reductions in left ventricular preload, systolic pressure (123 +/- 11 to 97 +/- 12 mm Hg) and stroke volume (24.2 +/- 4.3 to 19.1 +/- 5.2 ml). Right atrial contractility was augmented, as indicated by increases in peak A wave amplitude (ratio of peak A wave to mean right atrial pressure 1.22 +/- 0.02 to 1.46 +/- 0.3) and right atrial stroke work (0.11 +/- 0.02 to 0.25 +/- 0.05 g.m/m2). Right atrial ischemia depressed right atrial contraction, as indicated by decreased A wave amplitude (ratio of peak A wave to mean right atrial pressure 1.46 +/- 0.3 to 1.04 +/- 0.2) and stroke work (0.25 +/- 0.05 to 0.04 +/- 0.01 g.m/m2).(ABSTRACT TRUNCATED AT 250 WORDS)     

Beta-adrenoceptor density and relative number of beta-adrenoceptor subtypes in biopsies from human right atrial, left ventricular, and right ventricular myocard

In the present study we estimated the relative number of beta-adrenoceptors in membrane preparations from right atrial and left ventricular biopsies from 8 patients, as well as from right ventricular biopsy from one patient. Determinations of relative number of beta adrenoceptor subtypes (beta1, beta2) were also performed. Estimations were performed in a radioligand assay, measuring specific binding of [125I]-cyanopindolol (CYP). Inhibition of specific [125I] CYP binding was studied by adding propranolol (non-selective antagonist), atenolol (beta1 selective antagonist) and ICI 118551 (beta2 selective antagonist) to the preparations. Some individual variance in total number of receptors was found. Per mg protein, the number of binding sites were higher in atrial preparations (mean 71.4 +/- 14.4 fmol X mg-1) than in left ventricular preparations (mean 30.2 +/- 7.1 fmol X mg-1). Receptor number in the right ventricular preparation was 49.5 +/- 2.6 fmol X mg-1. Approximately 25% of beta adrenoceptors were of beta2 subtype in preparations from both right atrial and left ventricular biopsies, as well as from the right ventricular biopsy. Thus, there are regional differences in the quantity of beta adrenoceptors in human myocard whereas the relative proportion of beta1 and beta2 receptors appears to be fairly constant.     

右室起搏对左房容积指数及P波离散度的影响

目的 比较右室流出道间隔部(RVS)起搏与右室心尖部(RVA)起搏对左房容积指数、房性心律失常及P波离散度的影响.方法 选择RVS起搏及RVA起搏各36例,无器质性心脏病,其中DDD起搏30例,VVI起搏6例,行左房容积指数、24h房性心律失常、P波离散度(Pd)及最大P波时限(Pmax)检测,进行对比.结果 36例R...     

Successful treatment of right ventricular failure with atrial septostomy

In the case reported, a patient with severe right ventricular failure following coronary revascularization was successfully weaned from cardiopulmonary bypass following creation of an atrial septal defect. This technique facilitated rapid decompression of the failing right ventricle by shunting blood to the more compliant left ventricle, thus augmenting left ventricular preload and enhancing cardiac output. Recovery of right ventricular function was demonstrated by progressive hemodynamic improvement, as well as reduction of right-to-left intracardiac shunting and resolution of arterial hypoxemia.     

An unusual ventricular loop associated with right juxtaposition of the atrial appendages

We report two autopsied cases of an unusual ventricular loop in hearts with right-sided juxtaposition of the atrial appendages. Case 1 showed usual atrial arrangement, a concordant atrioventricular connexion with a disharmonious ventricular loop showing left-hand topology and double outlet right ventricle with normally related arterial trunks. The atrioventricular connexions were crossing, with the inlet to the left-sided morphologically right ventricle being posterior to that of left ventricle. Mitral hypoplasia and coarctation of the aorta were the associated lesions. The second case showed usual atrial arrangement, a discordant atrioventricular connexion with an imperforate left atrioventricular orifice and double outlet right ventricle with the aorta in the right-sided position. A large right atrium was connected to right-sided morphologically left ventricle. A prominent dimple in the left atrial floor was firmly attached to the hypoplastic right ventricle which was left-sided and anterior. A small but discrete inlet portion of the right ventricle could be traced towards the anteriorly located left atrial dimple. Thus, despite the presence of a discordant atrioventricular connexion with the usual atrial arrangement, there was righ-hand ventricular topology. In each case the inlet component of the ventricular septum was displaced, being to the right in case 1 and anteriorly in case 2. We suggest that the embryologic mechanism producing disharmony between the atrioventricular connexion and the segmental combinations be interpreted on the basis of posterior ventricular looping, since they are best explained on the basis of a hypothetical heart with posteriorly located outflow tracts.     

Atrial involvement in arrhythmogenic right ventricular dysplasia: primary or secondary? Description of a case of occult ventricular dysplasia with right atrial enlargement and exclusively sinoatrial arrhythmia

The atrial involvement in patients with arrhythmogenic right ventricular dysplasia is very rarely described. We here describe a patient with right atrial enlargement suffering from classical sinus and atrial electrical disease (tachycardia-bradycardia syndrome); the associated echo-angiographic aspects of the right ventricle are compatible, even in the absence of ventricular tachyarrhythmias, with a concealed form of right ventricular dysplasia. A common pathogenetic mechanism for the atrial and ventricular involvement is hypothetically considered.     

Hemodynamic importance of systolic ventricular interaction, augmented right atrial contractility and atrioventricular synchrony in acute right ventricular dysfunction

To delineate the determinants of right ventricular performance with acute right ventricular dysfunction, surgical electrical isolation of the right ventricular free wall was produced in 13 dogs. During atrioventricular (AV) pacing, hemodynamic and wall motion measurements were normal. When not paced, the right ventricular free wall became asystolic, resulting in a depressed and bifid right ventricular systolic pressure (33 +/- 5 to 18 +/- 4 mm Hg) and decreased left ventricular systolic pressure (100 +/- 18 to 80 +/- 18 mm Hg) and stroke volume (14 +/- 4 to 10.3 +/- 3.5 ml) (all p less than 0.05). Ultrasound demonstrated right ventricular free wall dyskinesia, increased right ventricular end-diastolic size (155 +/- 13% of control), but decreased left ventricular size (69 +/- 11% of control) (both p less than 0.05). Right atrial pressure increased (5.8 +/- 2.5 to 7.6 +/- 2.8 mm Hg, p less than 0.05) with an augmented A wave and blunted Y descent, indicating pandiastolic right ventricular dysfunction. The septum demonstrated reversed curvature in diastole and bulged paradoxically into the right ventricle during early systole, generating the initial peak of right ventricular pressure and reducing its volume. Later, posterior septal motion coincided with maximal left ventricular pressure and the second peak of the right ventricular waveform. Left ventricular pacing alone led to further decreases in right ventricular systolic pressure and size, left ventricular systolic pressure and stroke volume. The previously augmented A wave was replaced by a prominent V wave. Therefore, when contractility of its free wall is acutely depressed, right ventricular performance is dependent on left ventricular-septal contractile contributions transmitted by the septum.(ABSTRACT TRUNCATED AT 250 WORDS)     

An echocardiographic study of perimembranous ventricular septal defect with left ventricular to right atrial shunting

Twenty nine patients with isolated perimembranous ventricular septal defects were investigated by M mode, cross sectional, and pulsed Doppler echocardiography. Tricuspid valve anomalies were present in all six patients with a left ventricular-right atrial shunt but in only six (26%) of 23 patients who had interventricular shunts only. Systolic flutter of the tricuspid valve was shown in five (83%) of the six patients with a ventriculoatrial shunt but not in the other patients. Systolic turbulence in both the right ventricle and right atrium was detected by Doppler echocardiography only in patients with ventriculoatrial shunting. A perimembranous ventricular septal defect with left ventricular to right atrial shunt can be diagnosed by its combined M mode, cross sectional, and pulsed Doppler echocardiographic features.     

采用普通心房电极行右室流出道起搏的初步探讨

目的探讨心房J型电极在右室流出道(RVOT)起搏的临床应用。方法对8例采用普通心房电极行RVOT起搏(其中5例进行了永久性置入)的患者进行了起搏阈值测定及随访。结果心房电极行RVOT起搏,起搏阈值、R波振幅和电极阻抗与心尖部起搏比较无差异(P>0.05);操作简单、起搏成功率高。随访3~6个月无电极脱位,起搏功能良好。结论普通心房J型电极似可以替代螺旋电极行RVOT永久起搏。     

Echocardiographic findings in left ventricular to right atrial shunts.

The echocardiographic abnormalities of tricuspid valve motion in 2 patients with left ventricular to right atrial shunts are described. In both patients the abnormal anatomy was defined at surgery, in one patient the shunt being above the tricuspid valve leaflets (supravalvar) and in the other patient through the septal leaflet (intravalvar). Different patterns of tricuspid valve systolic fluttering were seen in these two cases and the possible reasons for this are discussed. After surgical closure of the defects the systolic fluttering of the tricuspid valve was no longer observed. Echocardiography appears to be useful in detecting the presence of left ventricular to right atrial shunts which otherwise may be difficult to diagnose.     

Relationship between mean right atrial pressure and Doppler parameters in patients with right ventricular infarction

BACKGROUND: The incidence of an inferior left ventricular infarction involving the right ventricle is very high, ranging from 14 to 84%. Isolated right ventricular infarction accounts for < 3% of all cases of infarction. HYPOTHESIS: The aim of the present study was to assess the relationship between Doppler parameters of hepatic vein and tricuspid inflow, as well as mean right atrial (RA) pressure in patients with right ventricular infarction. METHODS: In all, 59 consecutive patients with inferior left ventricular infarction involving the right ventricle were selected for the study. All patients underwent Doppler echocardiographic evaluation of tricuspid and hepatic vein parameters and catheterization of the right side of the heart. Patients were divided into two groups according to the presence or absence of severe tricuspid regurgitation. RESULTS: In patients with severe tricuspid regurgitation, a significant correlation (r = 0.64; p < 0.001) between RA maximal volume and mean right atrial pressure (RAP) was found, and the sensitivity of RA maximal volume in identifying mean RAP > 7 mmHg was 64% with a specificity of 78%. In patients without severe tricuspid regurgitation, the most significant relationship was observed between mean RAP and inferior vena cava collapse index. Significant correlations between maximal and minimal diameters of the inferior vena cava were also observed. CONCLUSIONS: Echocardiographic and Doppler parameters may be useful for evaluating mean RAP in patients with right ventricular infarction. In patients with severe tricuspid regurgitation, the more important parameters are maximal and minimal RA volumes. In patients without severe tricuspid regurgitation together with right atrial volume, the important parameters are acceleration and deceleration time of the tricuspid inflow peak E velocity and hepatic systolic and diastolic venous flow.     

An echocardiographic study of perimembranous ventricular septal defect with left ventricular to right atrial shunting.

Twenty nine patients with isolated perimembranous ventricular septal defects were investigated by M mode, cross sectional, and pulsed Doppler echocardiography. Tricuspid valve anomalies were present in all six patients with a left ventricular-right atrial shunt but in only six (26%) of 23 patients who had interventricular shunts only. Systolic flutter of the tricuspid valve was shown in five (83%) of the six patients with a ventriculoatrial shunt but not in the other patients. Systolic turbulence in both the right ventricle and right atrium was detected by Doppler echocardiography only in patients with ventriculoatrial shunting. A perimembranous ventricular septal defect with left ventricular to right atrial shunt can be diagnosed by its combined M mode, cross sectional, and pulsed Doppler echocardiographic features.     

Abnormal right ventricular size and ventricular septal motion after atrial septal defect closure: etiology and functional significance.

Postoperative echocardiogram often demonstrate persistent right ventricular dilatation and paradoxic ventricular septal motion after repair of an atrial septal defect. To determine the prevalence, causes and significance of these echocardiographic abnormalities, 31 patients were studied with catheterization and echocardiography before and after repair of an atrial septal defect. Before operation, every patient manifested right ventricular dilatation, and all but one had abnormal septal motion. After operation, right ventricular dilatation was noted in 24 (77%) and abnormal septal motion in 21 (68%) patients despite the absence of residual left to right shunting in 30 (97%). These echocardiographic abnormalities could be correlated with age at operation and length of postoperative follow-up study but did not correlate with the degree of preoperative right ventricular enlargement or with shunt size or right ventricular pressure before or after operation. There was no associated functional deficit as demonstrated by the normal maximal oxygen consumption in all 13 patients who underwent treadmill exercise testing 5 to 38 months after operation; these patients included 9 with persistent right ventricular enlargement and abnormal septal motion.     

Transcatheter closure of atrial septal defect preserves right ventricular function

Objectives: To determine the effects of atrial septal defects (ASD) and their closure on systolic and diastolic right and left ventricular function; and by comparing surgical closure with transcatheter device closure, to establish differences attributable to cardiopulmonary bypass.     

Radionuclide analysis of right and left ventricular response to exercise in patients with atrial and ventricular septal defects

In patients with ventricular or atrial septal defect, the ventricle which is chronically volume overloaded might not appropriately respond to increased demand for an augmentation in output and thereby might limit total cardiac function. In this study we simultaneously measured right and left ventricular response to exercise in 10 normal individuals, 10 patients with ventricular septal defect (VSD), and 10 patients with atrial septal defect (ASD). The normal subjects increased both right and left ventricular ejection fraction, end-diastolic volume, and stroke volume to achieve a higher cardiac output during exercise. Patients with VSD failed to increase right ventricular ejection fraction, but increased right ventricular end-diastolic volume and stroke volume. Left ventricular end-diastolic volume did not increase in these patients but ejection fraction, stroke volume, and forward left ventricular output achieved during exercise were comparable to the response observed in healthy subjects. In the patients with ASD, no rest-to-exercise change occurred in either right ventricular ejection fraction, end-diastolic volume, or stroke volume. In addition, left ventricular end-diastolic volume failed to increase, and despite an increase in ejection fraction, left ventricular stroke volume remained unchanged from rest to exercise. Therefore, cardiac output was augmented only by the heart rate increase in these patients. Right ventricular function appeared to be the major determinant of total cardiac output during exercise in patients with cardiac septal defects and left-to-right shunt.     

Hyposecretion of trial natriuretic peptide due to associated right atrial infarction in a patient with acute right ventricular infarction?

A patient with acute right ventricular infarction who showedhyposecretion of atrial natriuretic peptide (ANP) in spite ofabnormally high right atrial pressure and who died of a severelow cardiae output syndrome is reported. Right atrial infarction,which was proven at autopsy, may be responsible for this endocrinefailure.