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At least 307 records · Page 17Linked to original sources
PubMed1989

Left atrial conduit function for left ventricular filling dynamics in patient with myocardial infarction.

This study observed the left function in determining filling dynamics of the left ventricle in patients with myocardial infarction. The study consisted of eight control subjects and ten patients with myocardial infarction. The left ventricular filling volume is considered to be composed of the left atrial passive emptying, active emptying, and conduit volumes. The change of left ventricular filling volume was correlated with that of conduit volume (r = .87, P less than .01). However, the change of left ventricular filling volume did not have any correlation to those of left atrial passive emptying and active emptying volumes. These results suggested that the left atrial conduit function was important in determining filling dynamics of the left ventricle.

Adult↗
PubMed1989

Right ventricular myocardial function after atrial switch operation for transposition of the great arteries.

Postoperative right ventricular (RV) myocardial function was evaluated in 6 patients who underwent atrial switching for simple transposition of the great arteries (TGA). The average age at study was 5.5 years. RV function was evaluated at rest and during administration of methoxamine by cardiac catheterization and RV angiography. The data were compared with left ventricular function in a control group, which consisted of 6 patients, 3 with functional murmur and 3 with pulmonary valvar stenosis. During stress, the TGA group showed a significant increase in end-diastolic pressure, minute work index and end-diastolic and end-systolic volume indexes, along with a significant decrease in ejection fraction. The control group also showed an increase in these variables except for ejection fraction during stress, which did not change. The slope of the work-function curve for the TGA group was lower than that for the control group (p = 0.02). The TGA group had a lower slope of the peak systolic pressure-volume relation than the control group (p = 0.005). There was no significant correlation between the slope of the peak systolic pressure-volume relation and age at repair or study. This study shows that RV pump dysfunction observed in postoperative TGA patients may be caused by depressed myocardial function.

Cardiac Catheterization↗
PubMed1991

[Modified Fontan procedure, is the right atrial pump function necessary or not? Experimental approach using simulation model].

The effect of pulsatile pulmonary flow and the characteristics of pulmonary arterial pressure (PAP) trace were examined using a model simulating the right heart following the modified Fontan procedure. An inlet overflow tank (preload), valveless axial pulsatile pump, Windkessel model (afterload), and an outlet overflow tank (left atrium) were connected in series. Standard conditions were: flow 2.00 l/m, with 12 mmHg preload, 3.0 wood units resistance and left atrial pressure at 6 mmHg. The pump rate was set at 80 bpm. Simulated PAP and pulmonary flow (PF) waves produced by this model closely resembled those obtained from patients who had undergone the modified Fontan procedure. Parameters except preload were fixed and changes in PF were examined at varying preload of 8, 12, 15 and 17 mmHg. At the various preload levels, PF increased to values greater than the PF for the same conditions in the non-pulsatile state. With a preload value of 8 mmHg, PF increased from 1.10 l/m (non-pulsatile) to a maximum of 1.55 l/m at a peak PAP of 14 mmHg. With a preload of 12 mmHg, the PF increased from 2.00 l/m (non-pulsatile) to 2.65 l/m at 19 mmHg peak PAP. A preload of 15 mmHg resulted in an increase in PF from 2.65 l/m (non-pulsatile) to 3.30 l/m at 22 mmHg peak PAP, and when the preload was 17 mmHg the PF increased from 3.15 l/m (non-pulsatile) to 3.80 l/m at 25 mmHg peak PAP. The afterload of this model was fixed so the increase in PF with pulsation suggests a decrease in resistance.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Function, Right↗
PubMed1999

Mitral annulus velocity in the evaluation of left ventricular diastolic function in atrial fibrillation.

This study assessed the clinical utility of mitral annulus velocity in the evaluation of left ventricular diastolic function in patients with atrial fibrillation. Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice. The clinical usefulness of conventional Doppler indexes is limited in atrial fibrillation because of the altered left atrial pressure and loss of synchronized atrial contraction. Mitral inflow and mitral annulus velocities were measured simultaneously with tau in 27 patients with nonrheumatic atrial fibrillation at the cardiac catheterization laboratory. Among deceleration time of mitral inflow, peak mitral inflow velocity (E), and peak diastolic mitral annulus velocity (E), only E correlated with tau (r = 0.51, P =.007). Prolonged tau (>/=50 ms) could be predicted by E <8 cm/s with a sensitivity of 73% (16 of 22) and a specificity of 100% (5 of 5). The E/E ratio correlated with left ventricular filling pressure (r = 0.79, P <.001). The E/E ratio of >/=11 could predict elevated left ventricular filling pressure (>/=15 mm Hg) with a sensitivity of 75% (9 of 12) and a specificity of 93% (14 of 15). Mitral annulus velocity is useful in the detection of impaired left ventricular relaxation and estimation of filling pressure even in patients with atrial fibrillation.

Adult↗
PubMed1989

Effects of antihypertensive drugs on renal function and atrial natriuretic polypeptide in spontaneously hypertensive rats with renal ablation.

To determine whether pharmacological control of blood pressure could affect the renal function and levels of atrial natriuretic polypeptide (ANP) in spontaneously hypertensive rats (SHR) with renal ablation, and to ascertain the benefits of antihypertensive drugs, we studied effects of oral administration of captopril (50 mg/kg/day), an inhibitor of angiotensin converting enzyme, benidipine (3 mg/kg/day) and nilvadipine (10 mg/kg/day), newly developed blockers of calcium channel, and indapamide (10 mg/kg/day) for 14 days on systolic blood pressure, serum creatinine, blood urea nitrogen, and plasma ANP concentration in SHR subjected to surgical removal of the left kidney and infarction of two-thirds of the right kidney (5/6 nephrectomy) a week before. Three weeks after the surgery, systolic blood pressure (mmHg) in the untreated group was 253 +/- 9 (n = 10), in the captopril group 156 +/- 9 (n = 7, p less than 0.05), in the benidipine group 197 +/- 9 (n = 7, p less than 0.05), in the nilvadipine group 146 +/- 9 (n = 7, p less than 0.05) and in the indapamide group 206 +/- 5 (n = 7, p less than 0.05). Serum creatinine (mg/100 ml) was lower in the captopril group (0.58 +/- 0.02, n = 7, p less than 0.05) and in the benidipine group (0.50 +/- 0.03, n = 7, p less than 0.05) but not in the nilvadipine group and in the indapamide group 3 weeks after 5/6 nephrectomy compared to the untreated group. Blood urea nitrogen was also lower in the captopril group and in the benidipine group but not in the nilvadipine group and in the indapamide group. Plasma ANP concentration was significantly reduced by the treatment with captopril and benidipine but not with nilvadipine and indapamide. These results suggest that the reduction of blood pressure by the inhibition of angiotensin converting enzyme with captopril has the potential to ameliorate renal function of the SHR with remnant kidney, a model of chronic renal failure with hypertension, associated with the decreased concentration of plasma ANP. However, it remains to be determined whether the reduction of blood pressure by calcium channel blockers may be involved in the delayed progression of renal failure in this model since there were disparate effects on renal function and plasma ANP concentration with these two calcium channel blockers.

Animals↗
PubMed1999

Influence of right ventricular stimulation site on left ventricular function in atrial synchronous ventricular pacing.

OBJECTIVES: The study investigates the correlation between left ventricular function and QRS duration obtained by alternate right ventricular pacing sites. BACKGROUND: 1. Right ventricular apical pacing is associated with alterations of left ventricular contraction sequence. 2. A stimulation producing narrow QRS complexes is supposed to provide for better left ventricular contraction patterns. METHODS: Fourteen patients with third degree AV block received one ventricular pacing lead in apical position. The alternate lead was attached to that site on the septum that produced the smallest QRS complex as measured from the earliest to the last deflection in any of the orthogonal Frank leads (xyz). During atrial synchronous ventricular pacing, the AV delay was optimized individually and for each stimulation site using mitral valve doppler or impedance cardiography. By radionuclide ventriculography, the phase distribution histogram of left ventricular contraction was evaluated as area under the curve (AuC); systolic function was determined as ejection fraction (EF) and as absolute ejected counts (EC) in random order. The difference (delta) in QRS duration between apical and septal stimulation (deltaxyz) was correlated with the difference in phase distribution (deltaAuC) and ejection parameters (deltaEF, deltaEC). RESULTS: QRS duration was shorter with septal than with apical pacing in 9 out of 14 patients (64%); it was longer in 4 (29%), and no difference was seen in 1 patient. There was a significant positive correlation between the change in QRS duration (deltaxvz) and phase distribution (deltaAuC: r = 0.66393, p = 0.010) and a significant negative correlation to systolic function (deltaEF: r = 0.70931, p = 0.004; deltaEC: r = 0.74368, p = 0.002). CONCLUSIONS: In atrial synchronous right ventricular pacing, if the AV delay is adapted individually, decreased QRS duration obtained by alternate pacing sites is significantly correlated with homogenization of left ventricular contraction and with increased systolic function in acute tests.

Aged↗
PubMed2001

Inhibition of the Na(+)/H(+) exchanger delays the development of rapid pacing-induced atrial contractile dysfunction.

BACKGROUND: Atrial mechanical stunning due to atrial fibrillation may persist after restoration of sinus rhythm. Although the mechanism of rapid rate-related contractile dysfunction remains unknown, ischemia, pH changes, and calcium overload have been postulated as potential mechanisms. We hypothesized that blockade of the Na(+)/H(+) exchanger (NHE) would alter atrial contractile dysfunction from rapid rates. METHODS AND RESULTS: Twenty-three anesthetized dogs were studied and subjected to 5 hours of rapid right atrial pacing. Ten received an inhibitor of the NHE, 10 received saline, and 3 received nifedipine. All animals underwent placement of 2 sonomicrometers on the left atrium, transesophageal echocardiography, and invasive hemodynamic monitoring. All measurements were made in sinus rhythm. Except for baseline and postdrug measurements, reduction in left atrial fractional shortening was significantly less at all time points in the NHEI group than in the control and nifedipine groups (P:=0.05). The percent change from baseline of left atrial function at all time intervals as assessed by left atrial appendage contraction velocity (LAACV) was significantly less in the NHEI group than in the control (P:=0.05) group. LAACV was significantly preserved at all time intervals (except 300 minutes) in the NHEI group compared with the nifedipine group (P:=0.05). The only significant difference in hemodynamics among the groups was between the control and the nifedipine groups at 30 minutes after drug (P:=0.05). CONCLUSIONS: Treatment with HOE642 significantly blunts the decline in left atrial mechanical function from rapid atrial rates compared with both control and nifedipine-treated groups.

Analysis of Variance↗
PubMed1996

Early assessment by transesophageal echocardiography of left atrial appendage function after percutaneous mitral commissurotomy.

Thirty-seven consecutively admitted patients with severe mitral stenosis underwent percutaneous mitral commissurotomy with a transthoracic and biplane or multiplane transesophageal echocardiographic examination before and between 24 and 48 hours after percutaneous mitral commissurotomy. Thirty patients (81%) were in sinus rhythm and 7 were in atrial fibrillation. Left atrial appendage (LAA) function was evaluated in both the transverse and the longitudinal planes by planimetry and pulsed Doppler echocardiographic interrogation at the LAA outlet. Percutaneous mitral commissurotomy resulted in a twofold increase in mitral valve area, and no severe mitral regurgitation occurred. With use of the planimetry method, there was no significant improvement in LAA ejection fraction, except in the transverse plane for patients in sinus rhythm (p = 0.03). With use of Doppler method, 3 distinct flow patterns were observed before the procedure: a "sinus pattern" in patients in sinus rhythm, and a "fibrillatory pattern" (n = 3) or a "no-flow pattern" (n = 4) in patients in atrial fibrillation. After commissurotomy, there was a marked increase in LAA peak Doppler velocity (+62%) and in LAA velocity time integral (+31%). Of the 4 patients in atrial fibrillation with a no-flow pattern, 2 had recovery of a typical effective fibrillatory flow pattern after the procedure. The increase in peak Doppler velocity after commissurotomy was related to the decrease or regression in left atrial spontaneous echo contrast, and correlated with the increase in mitral valve area, the decrease in tranmitral pressure gradient, and the increase in cardiac index; improvement in valve function after successful percutaneous mitral commissurotomy is associated with early improvement in LAA function.

Adult↗
PubMed1989

Doppler left ventricular diastolic filling abnormalities in aortic stenosis and their relation to hemodynamic parameters.

Doppler mitral flow indexes and their relation to invasively measured hemodynamic diastolic indexes were assessed in 13 patients with isolated aortic stenosis (AS), and compared to Doppler indexes in 10 normal subjects matched for age, heart rate, left ventricular (LV) ejection fraction and LV load. Patients with AS showed no difference in Doppler early filling (E) indexes, but demonstrated greater Doppler atrial filling (A) indexes in comparison to normal subjects: atrial velocity (89 +/- 31 vs 56 +/- 7 cm/s), atrial integral (11.4 +/- 4.8 vs 5.7 +/- 1.6 cm), A/E velocity (1.69 +/- 0.89 vs 1.06 +/- 0.26) and A/E integral (3.53 +/- 6.64 vs 0.81 +/- 0.27) (all p less than 0.05). Doppler indexes in patients with AS did not correlate with hemodynamic indexes of LV relaxation or chamber stiffness. Significant correlations were observed between Doppler and angiographic peak filling rates (r = 0.70) and between Doppler atrial filling velocity and LV end-diastolic volume (r = -0.66), LV end-diastolic pressure (r = -0.48) and LV ejection fraction (r = 0.53) (all p less than 0.05). These data indicate that, compared to matched normal subjects, most patients with AS have an increased atrial contribution to LV filling. However, in patients with decreased LV function, atrial function may also be depressed, as indicated by a decreased atrial contribution to LV filling, resulting in "normalization" of the Doppler mitral flow pattern.

Aged↗
PubMed1997

Relationship between left ventricular diastolic function and atrial natriuretic factor in never-treated mild hypertensives.

Using digitized M-mode echocardiograms, we evaluated the relationship between plasma atrial natriuretic factor (ANF) and morphofunctional characteristics of the left ventricle (LV) in 24 mild hypertensive men, never treated, with normal renal function. For each subject we collected a blood sample for plasma ANF evaluation and, immediately after, we recorded the LV echocardiogram. All the patients had normal LV diastolic diameter and systolic function; LV hypertrophy was present in 10 patients, 7 of whom had left atrial enlargement, and 13 patients had impaired LV diastolic function. ANF was similar between patients with and without LV hypertrophy, as well as between patients with and without left atrial enlargement, whereas ANF was significantly (P < .01) higher in patients with LV diastolic dysfunction than in patients with normal diastolic function. ANF was inversely correlated with both indices of diastolic function (peak lengthening rate and peak wall thinning rate), whereas it did not correlate with blood pressure, heart rate, end-systolic wall stress, and other LV parameters. In conclusion, from our results, ANF level in never-treated mild hypertensives is related neither to the degree of LV hypertrophy nor to the afterload, expressed as blood pressure or end-systolic wall stress, whereas it is mainly influenced by LV diastolic function: the diastolic impairment induces an increase in ANF level, probably through an increased atrial stretch.

Adult↗
PubMed1995

Left atrial size and function: assessment using echocardiographic automatic boundary detection.

OBJECTIVE: To evaluate the waveforms of left atrial area changes obtained by automated boundary detection with newly developed acoustic quantification technology. DESIGN: All subjects had measurements of left atrial areas taken in the apical four chamber, parasternal long axis, and parasternal short axis views using both conventional echocardiographic methods and automatic boundary detection on two occasions separated by at least a week. On the second visit measurements were also repeated in healthy volunteers after acute intravenous volume loading with 1 litre of saline over 2-5 minutes. SETTING: A university medical school echocardiographic laboratory. SUBJECTS: 12 healthy male volunteers and 8 patients with cardiac disease (5 with congestive heart failure, 1 with mitral stenosis, and 2 with hypertensive left ventricular hypertrophy, and dilated left atria). RESULTS: There was close correlation between conventionally derived left atrial areas and those obtained by automatic boundary detection, particularly in the apical four chamber view (r = 0.98). Both inter and intra observer variabilities (coefficient of variation) for left atrial areas measured by automatic boundary detection were good (4.7-14.2% and 8.1-18.6% respectively). The reproducibility (coefficient of variation) for derived indices of left atrial function, however, was much poorer (10.4-104.8% and 12.5-88% respectively). After acute volume loading significant increases in left atrial area were observed at all stages in the cardiac cycle. CONCLUSIONS: These data demonstrate that although the reproducibility of left atrial functional indices is poor, instantaneous left atrial cavity measurements with automatic boundary detection are reproducible. This suggests that automatic boundary detection may assist in serial non-invasive measurement of left atrial size to assess disease states and treatments.

Adult↗
PubMed1993

Resolution of atrial standstill in a child with myocarditis.

Atrial standstill is a rare disorder usually seen in adults with extreme myocardial disease. Etiologies described in the literature have included muscular dystrophy, familial amyloidosis, and rarely myocarditis. These etiologies usually lead to permanent atrial standstill and require ventricular pacing. We present a case of an 11-year-old black female who developed atrial standstill secondary to biopsy proven acute necrotizing myocarditis. Absence of atrial function was confirmed by surface electrocardiogram, echocardiogram, and an invasive electrophysiology study. Atrial function returned within 3 days of initiation of methyl-prednisolone. In cases of atrial standstill due to myocarditis, a delay in the placement of a permanent pacemaker with or without a trial of methylprednisolone may prove beneficial.

Acute Disease↗
PubMed2001

Maternal diastolic dysfunction and left ventricular geometry in gestational hypertension.

The objective of this study was to evaluate diastolic parameters and left ventricular geometry in gestational hypertension. Twenty-one consecutive pregnant women with gestational hypertension and 21 normotensive women matched for age and gestational age were enrolled in the third trimester of gestation. Echocardiographic and uterine color Doppler evaluations were performed. Systolic, diastolic, and mean blood pressure, total vascular resistance (TVR), and uterine resistance index were higher in hypertensive women than in control subjects (P<0.01). Left atrial function and cardiac output were significantly lower in gestational hypertension (P<0.01). Patients with gestational hypertension had longer left ventricular isovolumetric relaxation time (IVRT) (P<0.0001); lower velocity-time integral of the A wave (P<0.05) and of the diastolic pulmonary vein flow (P<0.05); and higher velocity-time integral of the reverse pulmonary vein flow (P<0.05). Systolic fraction of the pulmonary vein flow was higher in women with gestational hypertension than in control subjects (P<0.01); the difference in duration of pulmonary vein flow and A wave was closer to 0 in gestational hypertension (P<0.0001). Altered left ventricular geometry was found in 100% of hypertensive patients and in 19.05% of normotensive patients (P<0.001). IVRT, left ventricular end-systolic volume, atrial function, and uterine resistance index were directly related to TVR (P<0.01); deceleration time of the E wave showed a quadratic correlation with TVR (P<0.01). Gestational hypertension is characterized by an altered cardiac geometric pattern of concentric hypertrophy. The altered geometric pattern assessed during gestational hypertension is associated, in our study, with depressed systolic function, high TVR, altered diastolic function, and left atrial dysfunction. Deceleration time of the E wave, IVRT, and left atrial fractional area change, found in concomitance with the highest TVR, may be useful in the evaluation of cardiac function and hemodynamics present in pregnancy-induced hypertension.

Adult↗
PubMed1986

Radionuclide measurement of right ventricular function in atrial septal defect, ventricular septal defect and complete transposition of the great arteries.

Right ventricular (RV) function was assessed in 80 patients with congenital heart disease by first-pass and gated equilibrium radionuclide angiography. In 30 patients with a ventricular septal defect (VSD) the mean RV ejection fraction (+/- standard deviation) was 64 +/- 7%. In 30 patients with a secundum atrial septal defect it was 61 +/- 9% and in 20 patients with surgically corrected complete transposition of the great arteries it was 49 +/- 13%. These values are in close agreement with values established with cineangiography for similar groups of patients. The mean ejection fraction in the group with transposition of the great arteries was significantly less than in the group with VSD (p less than 0.001). Phase analysis of the equilibrium studies showed that there was delayed RV contraction in many patients in the absence of conduction abnormalities. This delay was significantly greater in patients with atrial septal defect than in those with VSD (p less than 0.05). There was a strong correlation between size of left-to-right shunt and phase delay in patients with VSD (r = -0.72). Thus, first-pass gated radionuclide angiography provides a valid measurement of RV ejection fraction, and delayed RV contraction on phase analysis may be a sensitive index of early RV dysfunction.

Adolescent↗
PubMed1996

AV nodal function during atrial fibrillation: the role of electrotonic modulation of propagation.

The irregular ventricular rhythm that accompanies atrial fibrillation (AF) has been explained in terms of concealed conduction within the AV node (AVN). However, the cellular basis of concealed conduction in AF remains poorly understood. Our hypothesis is that electrotonic modulation of AVN propagation by atrial impulses blocked repetitively within the AVN is responsible for changes in function that lead to irregular ventricular rhythms in patients with AF. We have tested this idea using two different simplified computer ionic models of the AVN. The first ("black-box") model consisted of three cells: one representing the atrium, another one representing the AVN, and a third one representing the ventricle. The black-box model was used to establish the rules of behavior and predictions to be tested in a second, more elaborate model of the AVN. The latter ("nine-cell" model) incorporated a linear array of nine cells separated into three different regions. The first region of two cells represented the atrium; the second region of five cells represented the AV node; and the third region of two cells represented the ventricle. Cells were connected by appropriate coupling resistances. During regular atrial pacing, both models reproduced very closely the frequency dependence of AV conduction and refractoriness seen in patients and experimental animals. In addition, atrial impulses blocked within the AV node led to electrotonic inhibition or facilitation of propagation of immediately succeeding impulses. During simulated AF, using the nine-cell model, random variations in the atrial (A-A) interval yielded variations in the ventricular (V-V) interval but there was no scaling, i.e., the V-V intervals were not multiples of the A-A intervals. As such, the model simulated the statistical behavior of the ventricles in patients with AF, including: (1) the ventricular rhythm was random; and (2) the coefficient of variation (standard deviation/mean) of the ventricular rhythm was relatively constant at any given mean V-V interval. Analysis of cell responses revealed that repetitive atrial input at random A-A intervals resulted in complex patterns of concealment within the AVN cells. Consequently, the effects of electrotonic modulation were also random, which resulted in a smearing of the AV conduction curve over A-A intervals that were larger than those predicted for 1:1 AV conduction. Hence, during AF, electrotonic modulation acts in concert with the frequency dependence of AVN conduction to result in complex patterns of ventricular activation. Finally, similarly to what was shown in patients, VVI pacing of the ventricle in the nine-cell model at the appropriate frequency led to blockade of nearly all anterograde (i.e., A-V) impulses. The essential feature here was that the retrograde impulse invading the AVN cells was followed by refractoriness with slow recovery of excitability, setting the stage for electrotonic inhibition of anterograde impulses. Overall, the results provide insight into the cellular mechanisms underlying AVN function and irregular ventricular response during AF.

Animals↗
PubMed1997

Good exercise tolerance and impaired lung function after atrial repair of transposition.

OBJECTIVE: Evaluation of long-term results of atrial correction of transposition of the great arteries (TGA), focusing on the relationship between pulmonary function and exercise tolerance. METHODS: A prospective population-based study-56 out of 60 survivors of Mustard/Senning repair, born in Bohemia in 1980-1984 (median age at surgery 0.85 years) were followed up over 13.4 +/- 1.2 years and studied by complete lung function and bicycle exercise testing. RESULTS: Maximum heart rate on exercise reached 181 +/- 14 bpm (Z-score: -1.06 +/- 1.66, range -6.7 to +1.6); VO2max: 40.6 +/- 6.7 ml/kg per min (Z-score: -0.97 +/- 1.4, range -5 to +1.8). A total of 73.6% had abnormal lung function, most frequently features of stiff lung (39.6%) and lung restriction (32.1%). Static recoil pressure of the lungs measured at 100, 90 and 60% of total lung capacity reached 137, 126 and 130%, respectively (Z-score: 1.93 +/- 2.33, 1.64 +/- 1.96, and 1.14 +/- 1.95, respectively). There was an inverse relationship between static recoil pressure of the lungs and VO2max (r = -0.306, P = 0.043), indicating the impact of lung function abnormalities on exercise tolerance. Comparison with lung function study of the group of 'pioneer' Mustard patients operated at the mean age of 4.4 years revealed a similar pattern and frequency (73.6% in current series vs. 88%, NS). CONCLUSIONS: Long-term follow-up has shown good exercise tolerance in the majority of patients after atrial correction of TGA performed in infancy. Many of them, however, have impaired lung function, especially stiff lung, although less frequently than original patients operated at a later age. The stiff lung can impair the exercise tolerance.

Analysis of Variance↗
PubMed1992

[Evaluation of the diagnostic effectiveness of the indicators of left atrial myocardial function in intraoperative cardiac weakness in patients with mitral valve defects].

Excursions of the left-atrial myocardium were recorded by tensiometric transducers in patients with mitral valvular disease. The structural features of myocardial excursions were evaluated as symptoms. Myocardial shortening in P-Q interval was considered a negative symptom in relation to heart weakness, shortening in T-Q interval as an indefinite symptom, and shortening in Q-T interval as a positive symptom. Appraisal of the sensitivity and specificity of these symptoms revealed their high diagnostic efficacy.

Adolescent↗
PubMed1997

Comparative left ventricular function following atrial, septal, and apical single chamber heart pacing in the young.

Ventricular pacing, typically initiated from a RV apical electrode, inherently causes abnormal biventricular activation, decrease LV function, and causes histopathological changes. Since pacing initiated in childhood can be expected to have a more protracted course compared with the adult, the consequences of this alteration in LV hemodynamics gain added significance among the young pacemaker recipient. The purpose of this study was to evaluate the potential of improving paced LV function by a septal electrode implant site. Acute alterations in cardiac index, LV pressure, and contraction indices, including dP/dt, Vmax, and Vpm, were compared among 22 patients (median age 10 years) with normal cardiac anatomy during intracardiac electrophysiological studies. LV hemodynamics were measured during intrinsic rhythms and following 15 minutes of atrial, RV apical, and septal pacing at an appropriate exercise rate for age of 150 ppm. Results showed a significant decrease in LV dP/dt, Vmax, and Vpm, and increase in LV end-diastolic pressure only with apical pacing. Septal pacing, in spite of loss of any atrial contribution to ventricular filling, maintained comparable indices with intrinsic and atrial paced rhythms. This study demonstrates that normalized LV function is maintained by septal and deteriorates with apical pacing acutely among young, nonischemic hearts. Continued evaluation of appropriate pacing electrode designs to permit septal implant is needed to ensure optimal chronically paced LV function.

Adolescent↗