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PubMed1978

Cardiac function in the normal newborn: additional information by computer analysis of the M-mode echocardiogram.

Computer analysis of the M-mode echocardiogram in 50 normal newborns provided measurements of wall thicknesses and chamber size and, in addition, assessment of right and left ventricular wall, septal, and cavity dynamics throughout the cardiac cycle. Data obtained with this new technique indicated that (1) right and left ventricular cavity functions are similar in the normal newborn, (2) right and left ventricular cavity filling and emptying vary directly with peak rates of septal and ventricular wall thinning and thickening, respectively, and (3) there is a close time relationship among maximum left atrial dimension, minimum left ventricular dimension, and mitral valve opening. This analysis, which is the first complete analysis of the echocardiogram in the newborn, provides a normal range of septal and ventricular wall dynamics as well as right and left ventricular and left atrial function and has clinical implications in that it may allow early recognition of both congenital and perinatal myocardial disease.

Atrial Function↗
PubMed1981

[Exercise tests during cardiac catheterisation in patients with mitral regurgitation (author's transl)].

Left-heart catheterisation with angiocardiography and right-heart catheterisation during exercise were performed in ten patients with pure chronic mitral regurgitation. Those patients who at rest had large normal haemodynamic parameters had a rise in pulmonary wedge pressure on exercise from 13.1 +/- 4.8 to 26.0 +/- 9.1 mm Hg (P less than 0.001), as well as subsequently an exercise-induced pulmonary hypertension with a rise in pulmonary arterial mean pressure from 20.9 +/- 8.9 to 36.5 +/- 10.3 mm Hg (P less than 0.001). In addition, there occurred abnormalities of right ventricular function in four patients during exercise, with a rise in right atrial mean pressure above 10 mm Hg. On the other hand, in 12 patients with pure mitral stenosis and higher pressures in the pulmonary artery on exercise (43.9 +/- 10.2 mm Hg) (P less than 0.1), there was no abnormal rise in right atrial pressure. In patients with mitral regurgitation associated with abnormal right ventricular function during exercise, left ventricular function at rest was impaired (ejection fraction under 51%). There was a reciprocal correlation (r = -0.86) between the left ventricular ejection fraction at rest and the level of pulmonary artery pressure on exercise. Exercise-induced pulmonary hypertension in chronic mitral regurgitation with largely normal pressure values at rest is thus less the result of volume overload of the pulmonary circulation than an expression of impaired left ventricular pumping action. Abnormal right ventricular function which occurs on exercise is not a secondary consequence of pulmonary hypertension but goes parallel with abnormal function of the left ventricle.

Adult↗
PubMed1986

Right atrial pressure-volume relationships in tricuspid regurgitation.

Pressure-volume relationships in the right atrium were examined before and after the creation of acute experimental tricuspid regurgitation in pigs. A 1.3 kHz multielectrode impedance catheter with a measuring current of 4 mA was used to determine instantaneous right atrial pressure and relative blood volume; right atrial dimension was assessed simultaneously with ultrasonic crystals attached to the atrial walls. Impedance volume waveforms and ultrasonic crystal dimensions closely paralleled each other at baseline and after the induction of tricuspid regurgitation. The normal right atrial pressure-volume plot exhibited a figure-of-eight configuration, with an "a-loop" and a "v-loop" corresponding to the a-wave and v-wave of the right atrial pressure tracing. With severe tricuspid regurgitation, atrial pump function was abolished, and the pressure-volume plot exhibited a single clockwise loop, consistent with complete ventricularization of the right atrium. Intermediate degrees of tricuspid regurgitation preserved the figure-of-eight loop, but the size of both the a-loop and the v-loop were increased, consistent with a Starling-type load imposed on the atrium by the regurgitant blood volume. Increased right ventricular afterload mediated by constriction of the pulmonary artery and infusion of methoxamine reversibly converted the right atrial pressure-volume loop from that of mild to that of severe tricuspid regurgitation. Alternatively, constriction of the inferior vena cava and infusion of nitroprusside changed the right atrial pressure-volume loop from that of a severe pattern of tricuspid regurgitation to a less severe type of pattern. Infusion of dobutamine increased the size of the a-loop relative to the v-loop both at baseline and after induction of tricuspid regurgitation. We conclude that tricuspid regurgitation induces changes in right atrial mechanics that can be detected and quantified with an impedance catheter.

Animals↗
PubMed1989

Effects of atrial cardioplegia on the ischemic right ventricle after acute coronary artery occlusion and reperfusion.

Right atrial cardioplegia has been advocated as a simple method of delivering retrograde cardioplegia. Passive distention of the right heart inherent with right atrial cardioplegia has been shown to impair right ventricular function in a canine model of global ischemia. This study was designed to compare right ventricular performance after right atrial cardioplegia administered intermittently (n = 5) and continuously (n = 5) with coronary sinus retrograde cardioplegia (n = 5) and aortic root cardioplegia (n = 8) in a canine model of acute right ventricular ischemia and reperfusion. Right ventricular performance was assessed using the load-independent relationship of end-systolic pressure versus dimension (myocardial fiber length). Right ventricular performance was well preserved after reperfusion in those dogs protected with intermittent right atrial cardioplegia (95% of control). Results with continuous right atrial cardioplegia (66% of control) and coronary sinus retrograde cardioplegia (40% of control) demonstrated diminished postreperfusion right ventricular performance. Right ventricular performance in the group protected with aortic root cardioplegia was significantly impaired after reperfusion when compared with all retrograde groups (34% of control, p less than 0.05). In this model, postreperfusion right ventricular performance was preserved in the right atrial cardioplegia groups despite passive ventricular distention. All methods of retrograde cardioplegia resulted in superior preservation of right ventricular performance when compared with standard aortic root cardioplegia.

Animals↗
PubMed2005

Left ventricular function and chronotropic responses after normothermic cardiopulmonary bypass with intermittent antegrade warm blood cardioplegia in patients undergoing coronary artery bypass grafting.

OBJECTIVE: Recent studies indicate that normothermic cardiopulmonary bypass (CPB) with intermittent antegrade warm blood cardioplegia (IAWBC) may have metabolic and clinical advantages, but limited data exist on its effects on myocardial function. Therefore, we investigated the acute effects of this approach on systolic and diastolic left ventricular function and on chronotropic responses. METHODS: In 10 patients undergoing isolated CABG we obtained on-line left ventricular pressure-volume loops using the conductance catheter before and after normothermic CPB with IAWBC. Steady state and load-independent indices of left ventricular function derived from pressure-volume relations were obtained during right atrial pacing (80-100-120 beats/min) to determine baseline systolic and diastolic function and chronotropic responses. RESULTS: The mean time of CPB was 105+/-36 min (median 103, range 60-167 min) with a mean aortic cross-clamp time of 75+/-27 min (median 69, range 43-129 min). Baseline (80 beats/min) end-systolic elastance (E(ES)) did not change after CPB (1.22+/-0.53 to 1.12+/-0.28 mm Hg/ml, P>0.2), while the diastolic chamber stiffness constant (k(ED)) significantly increased (0.014+/-0.005 to 0.040+/-0.007 ml-1, P=0.018) and relaxation time constant (tau) significantly decreased (61+/-3 to 49+/-2 ms, P=0.004). Before CPB, incremental atrial pacing had no significant effects on E(ES) and tau but significant negative effects on kED (0.014+/-0.005 to 0.045+/-0.012 ml-1, P=0.013). After CPB, atrial pacing had significant positive effects on E(ES), tau and kED (E(ES): 1.12+/-0.28 to 2.60+/-1.54 mm Hg/ml, P=0.021; tau: 49+/-2 to 45+/-2 ms, P=0.009; kED: 0.040+/-0.007 to 0.026+/-0.005 mm Hg, P=0.010), indicating improved systolic and diastolic chronotropic responses. CONCLUSION: On-pump normothermic CABG with IAWBC preserved systolic function, increased diastolic stiffness, and improved systolic and diastolic chronotropic responses. Normalization of the chronotropic responses post-CPB is likely due to effects of successful revascularization and subsequent relief of ischemia.

Aged↗
PubMed1983

Alterations in cardiac performance in experimentally-induced diabetes.

Responses in cardiac tissue isolated from streptozotocin (STZ)-treated and age-matched control rats to isoproterenol (ISO) and calcium were studied. 4 weeks after STZ, atrial function was found to be depressed, whereas right ventricular function was enhanced. Neither tissue exhibited an alteration in sensitivity to ISO. In contrast, while sensitivity to calcium was found to be unaltered in atrial tissue, supersensitivity to calcium was observed in ventricles after STZ treatment. beta-Adrenoceptor number determination revealed a 36% decrease in Bmax with no change in affinity after STZ treatment. These results suggest that 4 weeks after STZ treatment pacemaker function is depressed, while enhancement in ventricular function is associated with an alteration in calcium utilization.

Animals↗
PubMed2001

Tezosentan (an intravenous endothelin receptor A/B antagonist) reduces peripheral resistance and increases cardiac power therefore preventing a steep decrease in blood pressure in patients with congestive heart failure.

OBJECTIVE: This study investigated the effect of tezosentan (an intravenous endothelin-1 receptor antagonist) on vascular resistance and cardiac function and determined the dose response in patients with stable congestive heart failure (CHF) due to left ventricular systolic dysfunction. METHODS: In a double-blind fashion, tezosentan or placebo were administered in ascending doses (5, 20, 50, 100 mg h(-1)) to 38 CHF (NYHA class III) patients with ejection fraction or=15 mmHg. Systemic vascular resistance index (SVRi) was estimated as mean arterial blood pressure [(MAP-right atrial pressure)/cardiac index (CI)]. Cardiac function was assessed as cardiac power index (Cpi), calculated as pressure x flow (MAP x CI), where MAP represents pressure and CI represents cardiovascular flow. RESULTS AND DISCUSSION: Compared to the placebo, tezosentan induced a dose-dependent decrease in SVRi (-32%), an increase in Cpi (+20%) and a small decrease in MAP (-9%). By contrast, patients treated with nitrate vasodilators or nesiritide (a natriuretic peptide) showed a decrease in SVRi not accompanied by a significant increase in Cpi leading to a steep decrease in MAP. CONCLUSIONS: The use of Cpi in the assessment of the hemodynamic effects of tezosentan, provides a useful alternative characterization of the complex influences of vasodilators on cardiac function in patients with CHF.

Adult↗
PubMed2006

[Cardiac remodeling in the light of immune status changes in patients with chronic obstructive pulmonary disease].

The degree of structural and functional heart changes was evaluated by means of Doppler echocardiography in 120 patients with chronic obstructive pulmonary disease (COPD) of different degrees of severity. Conventional immunological laboratory techniques were used in all the patients to evaluate the condition of cell-mediated, humoral, and cytokine-mediated immunity; inflammatory process activity and the degree of endotoxicosis were evaluated by measuring blood levels of acute phase proteins and medium mass molecules. The study showed that the character of heart remodeling depended on COPD severity. Only severe COPD was associated with a significant right atrial enlargement, as well as structural and functional changes in the left heart. The results demonstrated a distinct correlation between the variables of structural and functional condition of the heart and immunity parameters in COPD patients. The variables of right and left ventricular function moderately correlated with inflammatory and endotoxicosis indices. Decompensation of patients with severe COPD and cor pulmonale is accompanied by a pronounced immunodeficiency. An increase in blood levels of cytokines, tumor necrosis factor alpha in particular, may serve as a marker of early stages of chronic heart failure, while an increase in blood levels of interleukin-6 may be a marker of its severity.

Cytokines↗
PubMed1989

Clinical course of endomyocardial fibrosis.

The survival pattern, morbidity, and clinical course of 145 patients with endomyocardial fibrosis who were followed up between November 1975 and June 1987 were studied. The diagnosis was confirmed in all cases by cardiac angiography, or echocardiography, or necropsy. Percentage survival at the end of one and 9.5 years was 76.11 and 26.35 respectively. History, physical examination, electrocardiography, and cardiac catheterisation were studied at the first presentation. The determinants of early mortality were studied by univariate Kaplan-Meier estimates compared by the log rank test and Cox proportional hazards multiple regression analysis. Significant univariate predictors of early mortality were QRS axis above +90 degrees, intraventricular conduction delay (QRS duration greater than 0.12 s), duration of symptoms before presentation, New York Heart Association functional classes III and IV, presence of embolic episodes, right atrial mean pressures greater than 20 mm Hg, right ventricular end diastolic pressure greater than 20 mm Hg, and aortic oxygen saturation less than 85%. The significant multivariate predictors of mortality were cyanosis, New York Heart Association functional class at first presentation, and right atrial mean pressure greater than 20 mm Hg. The bleak prognosis of endomyocardial fibrosis did not substantially improve despite advances in the medical management of congestive cardiac failure during the period of the study.

Adult↗
PubMed2001

Effect of radiofrequency ablation on atrial myocardium.

OBJECTIVES: Successful RF ablation of atrial fibrillation supposedly requires the creation of continuous linear lesions. This study aimed to determine the potential role of functional modifications of atrial myocardium in the vicinity of anatomic RF lesions. METHODS: In 10 normal beagles (group A), a multiplexer mapping system and an epicardial multi-electrode were used to reconstruct atrial activation patterns during pacing at two cycle lengths before and after attempts to induce two linear right atrial lesions with a standard ablation catheter, respectively. An intercaval "drawback" was repeated 3 times over 5 min at a set temperature of 70 degrees C, followed by a transversal "point-by-point" ablation from the interatrial septum to the right-lateral tricuspid annulus at 70 degrees C/60 s each. Induction of atrial flutter was attempted before and after each ablation. In another 6 beagles (group B), a high-resolution multi-electrode was used to study epicardial functional effects resulting from single endocardial RF lesions on the free right atrial wall. Using three energy settings (60 degrees C/30 s, 60 degrees C/60 s, 70 degrees C/60 s), activation patterns were analyzed at two cycle lengths and local effective refractory periods were measured across the lesion. RESULTS: The lesions induced in group A only marginally affected atrial activation patterns and total activation times. However, as shown in dogs with atrial flutter, regional slow conduction was enhanced and functional conduction blocks were facilitated at high atrial rates, resulting in a significant prolongation in the revolution time of respective reentrant circuits. Apart from inducing anatomic lesions, single endocardial RF lesions (group B) were shown to delay epicardial conduction in adjacent myocardium in an energy- and rate-dependent way. Furthermore, an energy-dependent prolongation of effective refractory periods by far exceeding the size of anatomic lesions was observed. CONCLUSIONS: Continuous linear atrial lesions are hard to achieve with conventional ablation techniques. However, RF lesions induce changes in conduction and refractoriness around the anatomic lesion, which are likely to contribute to the overall effect of respective therapeutic interventions.

Animals↗
PubMed1993

A unified functional/anatomic substrate for circus movement atrial flutter: activation and refractory patterns in the canine right atrial enlargement model.

OBJECTIVES: This study was designed to test the concept of a functional/anatomic interaction in a canine model of reentry based on right atrial enlargement and to elucidate the electrophysiologic basis for functional conduction block. BACKGROUND: The monotonic feature of atrial flutter suggests a uniform substrate for the arrhythmia. Atrial flutter in the sterile pericarditis model is due to single-loop circus movement around a functional or a functional/anatomic obstacle near the atrioventricular (AV) ring. Sustained circus movement requires a critical interaction of a functional arc of block, a natural obstacle, the AV ring and a zone of slow conduction. The location of the inferior vena cava predisposes the lower right atrium to single-loop reentry. METHODS: In 11 dogs with right atrial enlargement, 127 bipolar epicardial electrograms were obtained during atrial flutter. For correlation of activation and refractory maps, the effective refractory period under each electrode was determined using the extrastimulus technique. RESULTS: Atrial flutter was due to single-loop reentry around functional arcs of block near the AV ring (n = 2) or around functional/anatomic obstacles (n = 8) involving the inferior vena cava. A slow zone was located between the arc and the AV ring and between the inferior vena cava and AV ring, respectively. During initiation, the arc joined the AV ring, forcing activation to proceed around the free end of the arc before breaking through the arc near the AV ring. Arrhythmia termination required the arc of block to rejoin the AV ring. Inducibility of sustained atrial flutter was associated with a marked spatial dispersion of refractoriness. The configuration of the functional arc of block was critically dependent on the spatial pattern of refractoriness. CONCLUSIONS: Atrial flutter requires a similar functional or functional/anatomic substrate independent of the underlying etiology. The spatial distribution of refractoriness in enlarged canine atria provides an adequate substrate for the development of functional conduction block.

Animals↗
PubMed1989

[Experimental study on the optimal size of the tricuspid valve annular area on annuloplasty].

The optimal size of tricuspid valve annular area (TVAA) by annuloplasty for tricuspid regurgitation remains controversial. Recently, we developed a new measuring system which permits to do real-time measurement of tricuspid valve annular area in anesthetized dogs. Using this system, we studied the optimal size of TVAA by annuloplasty. After the right atrial incision, a metal thread which functions as a sense loop of the electromagnetic fields was stitched along the tricuspid valve annulus (visible juncture of the valve leaflets and the cardiac wall). The drive coil assembly was placed perpendicular to the extension of the long axis of the heart and was directed toward the tricuspid valve region. During control conditions, the maximum TVAA appeared at the onset of ventricular systole. The minimum TVAA appeared during the early ventricular diastolic phase which included the ventricular isovolumic relaxation phase. The maximum TVAA varied in five dogs between 2.2 cm2 and 3.1 cm2, the minimum TVAA also varied between 1.8 cm2 and 2.5 cm2: During regular sinus rhythm, a decrease of TVAA during one cardiac cycle ranged between 11.9% and 22.4% of the maximum size. When TVAA was not decreased by annuloplasty to the minimum area which was observed during cardiac cycle in the control state, the cardiac output and the right atrial pressure remained unchanged, because the ventricular filling was not obstructed. On the other hand, when TVAA was decreased smaller than this minimum area, the cardiac output decreased and the right atrial pressure rose.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

[Ebstein's anomaly: long-term results after modified reconstruction of tricuspid valve without ventricle plication].

Ebstein's anomaly is a rare congenital heart defect in which the hinges of the septal and/or posterior leaflets are displaced downward to the right ventricle. The anterior leaflet is usually not displaced but is enlarged and sail-like and valve closure is likewise displaced downwards. Since 1988 we have operated on 22 patients with Ebstein's anomaly using a modified repair technique of the tricuspid valve. This technique restructures the valve mechanism at the level of the true tricuspid annulus by using the most mobile leaflet for valve closure without plication of the atrialized chamber. We evaluated our long-term results with regard to functional capacity (New York Heart Association functional class), tricuspid valve function, rhythm disturbances and re-operation rate. We quantified the right ventricular function by measuring flow velocity integral of the pulmonary artery (VTIPA). All patients survived the operation. There were two hospital deaths (9%) and the late mortality was 4.5%. The mean followup period was 9 years (range, 1.5 to 13 years) for 19 patients. So far no re-operation has been necessary. Preoperatively, the majority of all patients were in NYHA classes III and IV (79%). After the first postoperative follow-up examination (2.9 months), 17 patients were in NYHA class II. Long-term follow-up examinations showed an additional improvement of 11 patients to NYHA class I. Echocardiographic studies demonstrated a significant improvement of tricuspid valve function. No tricuspid valve stenosis was observed. Significant improvement of VTI(PA) was observed. Analysis of the postoperative deaths demonstrated that all patients were in NYHA class III or IV and had a cardiothoracic ratio of 0.65 or more. A severe reduction in functional capacity seems to be an additional risk factor for mortality beside a cardiothoracic ratio greater than 0.65. We conclude that reconstruction of the tricuspid valve without ventricle plication not only achieves good functional results immediately after the operation but that follow-up examinations demonstrate stable or improved functional capacity in the long term. We postulate that incorporation of the atrialized chamber into the right ventricle may contribute to right ventricular contraction and thereby account for the improved functional capacity of the patients.

Adolescent↗
PubMed1976

Results following physiological repair for tricuspid atresia.

Fourteen patients underwent a physiological operation for tricuspid atresia. Seven patients survived up to 3 years after operation. Six patients underwent hemodynamic studies 2 to 34 months postoperatively (mean, 15 months). Average age at the time of operation was 14 years (range, 5 to 25 years). Postoperative studies showed 4 patients to be in sinus rhythm and 2 in junctional rhythm. Right atrial pressure was elevated an average of 17 mm Hg (range, 10 to 34 mm Hg). All patients showed good atrial transport function regardless of their rhythm. Two had a right atrium-left pulmonary artery gradient of 1.5 to 10 mm Hg across the conduit. Average arterial saturation was 92% (range, 87 to 97%), on improvement of 13% over preoperative values. Residual hypoexmia was due to pulmonary vein desaturation and to atrial right-to-left shunting early postoperatively and later, to atrial right-to-left shunting alone.

Adolescent↗
PubMed2001

The effect of cardiomyoplasty on left atrial function in experimental canine models.

BACKGROUND: Cardiomyoplasty utilizes the latissimus dorsi muscle to boost the failing ventricle. However, the mechanism for clinical improvement still remains controversial. We have previously shown that left ventricular contraction was improved in the long-term periods after cardiomyoplasty in the normal canine heart model and in the dilated failing heart model. On the other hand, right ventricular filling was impaired if a rapid volume loading test was employed in the long-term period after cardiomyoplasty. The purpose of the present study was to determine whether cardiomyoplasty impairs the left atrial function and affects ventricular filling. METHOD: Eleven mongrel dogs that had undergone cardiomyoplasty (study group, n = 5) or a sham operation (control group, n = 6) were studied for 12 weeks postoperatively. An IV 4.5% albumin solution (10 mL/kg) was infused into the right atrium, and hemodynamic changes in right cardiac catheterization and left atrial volume (LAV) were obtained by two-dimensional echocardiography. Atrial function was assessed by hemodynamic changes in Doppler echocardiography and hormonal changes. RESULTS: Stroke volume was significantly increased, from 17.0 +/- 4.4 to 21.1 +/- 7.0 mL, respectively, before and 15 min after albumin infusion in the control group (p < 0.05). Heart rate and cardiac output were significantly increased, from 131.2 +/- 18.1 to 152.0 +/- 9.8 beats/min and 2.72 +/- 1.29 to 4.03 +/- 1.67 L/min, respectively, before and 15 min after albumin infusion in the study group (p < 0.05). No changes were observed in mean right atrial pressure and pulmonary capillary wedge pressure. LAV and atrial natriuretic peptide (ANP) levels increased significantly, from 5.8 +/- 2.1 to 8.5 +/- 3.8 mL and 22.5 +/- 7.5 to 44.5 +/- 31.7 pg/mL, respectively, before and 15 min after albumin infusion in the control group (p < 0.05). In the study group, LAV and ANP levels were also increased, from 10.1 +/- 2.4 to 12.7 +/- 2.8 mL and 64.2 +/- 60.6 to 232.6 +/- 272.2 pg/mL, respectively, before and 15 min after albumin infusion (p < 0.05). The peak velocities and the time-velocity integrals in the pulmonary venous flow of the systolic and diastolic waves, as well as their ratios (systolic to diastolic peak velocity ratio and systolic to diastolic time-velocity integral ratio) showed no significant differences between the two groups. CONCLUSIONS: Cardiomyoplasty preserves left atrial filling and transport function; therefore, cardiomyoplasty may also activate ANP production by stimulating the atrium in the long-term period after cardiomyoplasty.

Albumins↗
PubMed1993

The relationship between "normal" transesophageal color-flow Doppler-defined tricuspid regurgitation and thermodilution right ventricular ejection fraction measurements.

Twenty coronary artery revascularization patients, aged 58 +/- 15 years, were studied intraoperatively to define the impact of Doppler-defined tricuspid regurgitation on measurement of thermodilution right ventricular ejection fraction (50 msec response pulmonary artery catheter). Right ventricular function was also estimated using a measurement technique independent of flow patterns across the tricuspid valve (transesophageal two-dimensional echocardiographic 5.0 MHz phased-array transducer). Measurements included transverse plane long- and short-axis planimetered area ratio, respectively, and tricuspid annular plane systolic excursion ratio (ratio = end-diastolic minus end-systolic value divided by end-diastolic value). Data were expressed as thermodilution-echocardiographic gradients, ie, thermodilution ejection fraction minus long-axis planimetered area ratio, short-axis planimetered area ratio, and tricuspid annular plane systolic excursion ratio, respectively. Tricuspid regurgitation was quantified by color-flow Doppler perimetry of maximal regurgitation jet area and analysis of transduced right atrial pressure waveform. Doppler estimates were expressed as absolute values and as a function of corresponding atrial area (tricuspid regurgitation index = planimetered jet area divided by right atrial area). Data were obtained following endotracheal intubation, sternotomy, pericardiotomy, cardiopulmonary bypass, and chest closure. Data were evaluated by regression analysis, with separate analyses performed for each time period. Profiles were unassociated with right atrial pressure waveform abnormalities. There was no significant relationship between thermodilution ejection fraction variance values and tricuspid regurgitation jet area or regurgitation index, respectively. In each measurement period, thermodilution-echocardiographic gradients were also unrelated to the tricuspid regurgitation estimates.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheterization, Swan-Ganz↗
PubMed2001

Echocardiographic features of the right heart in sleep-disordered breathing: the Framingham Heart Study.

The effect of sleep-disordered breathing (SDB) on right heart structure and function is controversial. Studies of patients referred for evaluation of possible sleep apnea have yielded conflicting results, and the impact of SDB on the right heart has not been investigated in the general population. We examined the echocardiographic features of subjects with SDB at the Framingham Heart Study site of the Sleep Heart Health Study. Of 1,001 polysomnography subjects, 90 with SDB defined as a respiratory disturbance index (RDI) score > 90th percentile (mean RDI = 42) were compared with 90 low-RDI subjects (mean RDI = 5) matched for age, sex, and body mass index. Right heart measurements, made without knowledge of clinical status, were compared between groups. The majority of the subjects were male (74%). After multivariable adjustment, right ventricle (RV) wall thickness was significantly greater (p = 0.005) in subjects with SDB (0.78 +/- 0.02 cm) than in the low-RDI subjects (0.68 +/- 0.02 cm). Right atrial dimensions, RV dimensions, and RV systolic function were not found to be significantly different between subjects with SDB and the low-RDI subjects. We conclude that in this community-based study of SDB and right heart echocardiographic features, RV wall thickness was increased in subjects with SDB. Whether the RV hypertrophy observed in persons with SDB is associated with increased morbidity and mortality remains unknown.

Adult↗
PubMed1986

Alteration of human right bundle branch refractoriness by changes in duration of the atrial drive train.

We studied the effect of drive train duration on human right bundle branch refractoriness. Seven patients with a QRS duration of 0.10 sec or less and no preexcitation had functional right bundle branch block induced reproducibly with premature atrial stimulation. Refractoriness of the right bundle branch was defined as the longest H1H2 interval resulting in right bundle branch block and was determined in each patient at a constant pacing cycle length but at five to seven different atrial drive train durations varying from four to 99 complexes. In all seven patients, right bundle branch refractoriness decreased with increasing drive train duration (mean 15 msec). One-third of this decrease (5.0 msec) occurred between drive train durations of four and eight complexes, and close to two-thirds (9.3 msec) occurred between drive train durations of eight and 64 complexes. Very little further decrease (0.7 msec) occurred between 64 and 99 complexes. We conclude that right bundle branch refractoriness shortens progressively as the preceding drive train duration increases. This phenomenon may in part explain the disappearance of functional right bundle branch block during supraventricular tachycardia after a variable number of complexes without a change in cycle length of tachycardia.

Adult↗