Left ventricular diastolic function after electrical cardioversion of atrial fibrillation.
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Influence of pericardium on left atrial compliance and pulmonary venous flow.
We studied seven open-chest anesthetized dogs to test the hypothesis that left atrial (LA) compliance is increased after pericardiectomy and to determine the effect of pericardiectomy on left atrial reservoir and conduit function. Two orthogonal sonomicrometer crystal pairs were used to estimate LA volume, and LA filling was assessed with a pulmonary vein (PV) flow probe. The left ventricular (LV) systolic (JFTI) and diastolic (KFTI) PV flow integrals were used as indexes of LA reservoir and conduit function, respectively. Diastolic LV transmitral flow was assessed with transesophageal Doppler echocardiography. Data were acquired over a wide range of intracardiac pressures and volumes obtained by intravenous hetastarch infusion both before and after pericardiectomy. The mean dynamic stiffness constant of the LA diastolic pressure-volume relation was significantly greater before pericardiectomy than afterwards (0.15 +/- 0.04 vs. 0.08 +/- 0.03 ml-1, P < 0.05). Data were analyzed before and after pericardiectomy at three matched levels of left atrial pressure (LAP; 7, 13, and 20 mmHg). The J-to-KFTI ratio increased significantly with volume infusion and was significantly less after pericardiectomy than before (1.2 +/- 0.7 vs. 1.2 +/- 0.6, 1.8 +/- 0.6 vs. 2.2 +/- 0.9, and 2.0 +/- 0.8 vs. 2.6 +/- 0.9 at low, mid, and high levels of LAP, respectively; P < 0.05 at mid and high levels of LAP). Peak early transmitral velocity increased with both volume infusion and pericardiectomy. We conclude that pericardiectomy increases LA compliance and early LV filling rate and is accompanied by a relatively greater augmentation in conduit than reservoir function of the left atrium.
Animals↗
Analysis of left atrioventricular plane movement during diastole in ischemic heart disease.
The aim of the present study was to investigate the properties of diastolic left atrioventricular plane displacement (AVPD) in coronary artery disease (CAD) patients. In 125 patients (mean age 58.7 +/- 13.7) with CAD and in 51 age-matched healthy subjects, a complete transthoracic echocardiographic study was performed. The AVPD was recorded by M-mode echocardiography, from apical four and two chamber views at four sites corresponding to the septal, lateral, anterior and inferior walls of the left ventricle. Mean AVPD in early diastole (E-AVPD), mean AVPD from atrial systole (A-AVPD) and the ratio A-AVPD/E-AVPD were determined. In normal subjects, such as in 35 patients without left ventricular segmental wall motion abnormalities (SWMA), stepwise multiple regression analysis showed none of these factors to be significantly related to E-AVPD or A-AVPD. Aging was correlated negatively to the E-AVPD/A-AVPD ratio (p < 0.05). In 90 patients with left ventricular SWMA, stepwise multiple regression analysis showed that indices of left ventricular systolic function correlated positively to E-AVPD (p < 0.001) and A-AVPD (p < 0.001). The E-AVPD/A-AVPD ratio was correlated to left ventricular ejection fraction and heart rate (p < 0.005). Mean E-AVPD was significantly lower in CAD patients than in normal subjects (p 0.001), while A-AVPD was higher in patients without left ventricular SWMA in comparison to normal subjects (p = 0.02). Also, mean A-AVPD/E-AVPD was higher in CAD patients than in the control group (p < 0.001). Mean E-AVPD/A-AVPD was correlated to the E/A ratio of transmitral flow in CAD patients with (r = 0.669) and without (r = 0.771) SWMA. The E-AVPD and A-AVPD in CAD patients with SWMA is reduced according to the deterioration of left ventricular systolic function. The atrial contribution to the longitudinal distension of the left ventricle is increased in CAD patients. In CAD patients, especially those without left ventricular SWMA, the E-AVPD/A-AVPD ratio has a good correlation to left ventricular filling behavior.
Age Factors↗
Prevalence and clinical significance of left atrial thrombus in nonrheumatic atrial fibrillation.
The prevalence and clinical significance of left atrial thrombus were prospectively investigated in a consecutive series of 219 patients with chronic nonrheumatic atrial fibrillation using transesophageal echocardiography. Fifteen left atrial thrombi were detected in 15 of the 219 patients (6.8%); 12 of these thrombi (80%) were confined to the left atrial appendage. Left atrial spontaneous echo contrast was visualized in 85 patients (39%). All the thrombi were found in the left atria with spontaneous echo contrast. Patients with left atrial thrombus had significantly lower left ventricular ejection fraction than those without (49 +/- 14% vs. 59 +/- 14%; P < 0.05). Multivariate analysis among clinical and transthoracic echocardiographic variables showed that left ventricular ejection fraction < 50% was the only independent predictor for the presence of left atrial thrombus. A history of thromboembolism was significantly more frequent in patients with left atrial thrombus than in those without (73% vs. 32%; P < 0.005). The presence of left atrial thrombus was more specific than spontaneous echo contrast for predicting history of thromboembolism (97% vs. 80%), but its sensitivity was significantly lower (14% vs. 73%). We conclude that: (1) Transesophageal echo-detected left atrial thrombus is not uncommon in patients with chronic nonrheumatic atrial fibrillation and is exclusively observed in those with left atrial spontaneous echo contrast. (2) Impaired left ventricular systolic function may predispose the left atrial thrombus formation. (3) Left atrial thrombus is a highly specific but insensitive predictor for thromboembolic events.
Adult↗
Course of left ventricular hypertrophy and function in end-stage renal disease after renal transplantation.
Cardiovascular complications are frequent and related to left ventricular (LV) hypertrophy and dysfunction in end-stage renal disease. To examine cardiac changes after renal transplantation, 24 hemodialysis patients (18 men and 6 women, age 47 +/- 12 years) were analyzed in a prospective follow-up study with echocardiography immediately before and 41 +/- 30 months after renal transplantation. Mean systolic blood pressure (hemodialysis vs transplantation: 156 +/- 35 vs 144 +/- 15 mm Hg; p = not significant [NS]), as averages of 6 measurements from 2 weeks, remained constant and elevated. The most frequent echocardiographic findings at both assessments were left atrial dilatation (75 vs 79%; p = NS) and LV hypertrophy (71 vs 67%; p = NS). After transplantation, an increase was found in mean left atrial diameter (41 +/- 5 to 44 +/- 5 mm; p < 0.05) and end-diastolic LV diameter (50 +/- 5 to 53 +/- 5 mm; p < 0.05) at constant LV muscle mass (332 +/- 104 vs 329 +/- 94 g; p = NS). LV ejection fraction (58 +/- 10% to 63 +/- 12%; p < 0.02) and stroke volume (98 +/- 26 to 118 +/- 25 ml; p < 0.02) improved. No influence of blood pressure in sporadic morning determinations or of dialysis fistula patency on alterations of LV mass or function was found. Left atrial diameters increased in patients with patent dialysis fistulas (41 +/- 7 to 45 +/- 5 mm; p < 0.05), but not in those with occluded fistulas (41 +/- 7 vs 42 +/- 4 mm; p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Arteriovenous Shunt, Surgical↗
Left atrial appendage flow velocities in subjects with normal left ventricular function.
The objectives of this study were to establish reference values and define the determinants of left atrial appendage (LAA) flow velocities in the general population. LAA flow velocities (contraction and filling velocities) were assessed by transesophageal echocardiography in 310 subjects aged > or = 45 years, sampled from the population-based Stroke Prevention: Assessment of Risk in a Community study. All subjects were in sinus rhythm, with preserved left ventricular systolic function (ejection fraction > or = 50%), and without valvular disease. Values of LAA contraction and filling velocities were established for various age groups in the population. Age was negatively associated with LAA contraction and filling velocities, which decreased by 4.1 cm/s (p < 0.001) and 2.0 cm/s (p < 0.01) for every 10 years of age, respectively. Contraction velocities were 5 cm/s higher in men than in women (p < 0.05). After adjusting for age and sex, heart rate was independently associated with LAA contraction velocities (p < 0.001; nonlinear association). Body surface area, left atrial size, left ventricular mass index, and a history of previous cardiac disease or hypertension showed no significant association with LAA flow velocities (p > 0.05). Furthermore, detailed analysis of 24-hour ambulatory blood pressure data (available in 253 subjects) showed no association between various blood pressure parameters (systolic and diastolic blood pressure, out-of-bed and in-bed measurements) and LAA flow velocities (all p > 0.05). In summary, the present study establishes the reference values for LAA flow velocities in a large sample of the general population. LAA flow velocities progressively decline with age in subjects with preserved left ventricular systolic function.
Age Factors↗
Complexities in ETS-domain transcription factor function and regulation: lessons from the TCF (ternary complex factor) subfamily. The Colworth Medal Lecture.
The ETS-domain transcription factor family can be divided into a series of subfamilies. Elk-1 represents the founding member of the ternary complex factor (TCF) subfamily. By focusing on the TCF subfamily, we can demonstrate the complexities that exist in the function and regulation of ETS-domain transcription factors. This article focuses on Elk-1 in detail and summarizes the functions of other TCFs. The key themes covered include the domain structure of the TCFs, the mechanisms of complex formation with serum response factor, regulation of TCFs by mitogen-activated protein kinase cascades, and transcriptional regulatory properties of the TCFs. Finally, the emerging role of the TCFs in vivo is discussed. A picture is developing indicating that, while these proteins exhibit significant sequence and functional conservation, key differences in their structure and regulation are being identified which may relate to unique functions of these proteins in vivo.
Amino Acid Sequence↗
Safety and efficacy of internal cardioversion of atrial fibrillation in patients with impaired left ventricular systolic function.
In patients with structural heart disease and left ventricular ejection fraction <40%, internal cardioversion is a safe and effective method for converting persistent atrial fibrillation. The acute success rate and atrial defibrillation requirement for cardioversion in these patients is comparable to patients with lone atrial fibrillation and structurally normal hearts.
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Current management of atrial fibrillation.
A resurgence of interest in atrial fibrillation has led to research in several avenues. Observations on the behavior of the atrium during atrial fibrillation demonstrate that electrical activity is not entirely random and that sinus node activity persists despite surrounding fibrillation. Anticoagulation therapy for chronic atrial fibrillation is now accepted as optimal treatment, but randomized trials have excluded the majority of patients screened and the risk-benefit ratio of therapy in the average patient therefore remains unclear. This is being addressed in comparative trials of warfarin and aspirin and in an analysis of risk factors for stroke derived from a major trial. Assessment of the efficacy of therapy for the control of ventricular rate in atrial fibrillation has underscored the slow action of digoxin and raised the issue of suboptimal dosing. With the recognition that improvement of exercise capacity following cardioversion may be postponed for weeks, several studies have evaluated serial changes in ventricular function and shown that in some patients sinus rhythm is associated with an improved ejection fraction. Transesophageal echocardiography is an area of intense interest for the identification of patients at high risk of thromboembolism following cardioversion, and the significance of left atrial spontaneous echo contrast as well as the left atrial appendage contractile function are being investigated. Finally, new methods of arrhythmia termination are being evaluated and developed, and surgical approaches to atrial fibrillation are being expanded and refined.
Animals↗
Single-beat determination of Doppler-derived aortic flow measurement in patients with atrial fibrillation.
The clinical assessment of left ventricular systolic function in patients with atrial fibrillation is unreliable and difficult because of beat-to-beat variation. We initially evaluated an index that is on the basis of the ratio of preceding R-R (RR1) to pre-preceding R-R (RR2) intervals (RR1/RR2) for the measurement of Doppler aortic flow (peak flow velocity [Vp] and time-velocity integral [TVI] proportional to stroke volume) in 20 patients (aged 65 +/- 9.6 years) with atrial fibrillation. We obtained each parameter for >13 cardiac cycles, and the relationship between each parameter at a given cardiac beat and the RR1/RR2 ratio were evaluated by linear regression analysis. The value of each parameter at RR1/RR2 = 1 was calculated from the equation of linear regression line and compared with measured average value over all cardiac cycles. Both parameters showed a significant positive correlation with the RR1/RR2 ratio (Vp, r = 0.98, y = 1.01x + 0.61; TVI, r = 0.99, y = 1.01x + 0.26). The calculated value of each parameter at RR1/RR2 = 1 was quite similar to the average value (Vp, 97.4 +/- 30.8 vs 95.7 +/- 29.8 cm/s; TVI, 17.7 +/- 6.8 vs 17.3 +/- 6.7 cm, respectively). In the additional 20 patients (aged 77.4 +/- 15.2 years), Doppler aortic flow parameters of a single beat with identical RR1 and RR2 intervals were compared with measured average value over all cardiac cycles and showed similar results (Vp, r = 0.99, y = 0.99x + 3.4, P <.0001, bias -0.5 cm/s; TVI, r = 0.99, y = 0.92x + 1.5, P <.0001, bias 0.1 cm). In conclusion, the Doppler aortic flow at RR1/RR2 = 1 allows the left ventricular systolic parameters to be accurately evaluated during atrial fibrillation and obviates the less reliable process of averaging multiple irregular beats.
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Prospective evaluation of transesophageal pacing for the interruption of atrial flutter.
PURPOSE: Although transesophageal pacing has been used successfully for the interruption of cardiac arrhythmias, the efficacy of this technique for the interruption of spontaneous atrial flutter remains poorly defined. The utility of transesophageal pacing to interrupt atrial flutter that was persistent despite standard antiarrhythmic drug therapy (mean duration: 70.3 days; range: one day to more than 365 days) was studied prospectively in 39 consecutive patients. PATIENTS AND METHODS: After written informed consent was obtained from each patient, transesophageal pacing was performed with a programmable stimulator, using the distal electrode as the cathode and the proximal electrode as the anode. All patients continued to receive a type 1 antiarrhythmic drug or amiodarone throughout the period of transesophageal pacing. The response to transesophageal pacing was classified as follows: (1) direct conversion; (2) indirect conversion; or (3) failure to interrupt atrial flutter. RESULTS: The mean stimulus amplitude and pulse duration required for atrial capture were 19.8 +/- 7.5 mA and 18.4 +/- 7.9 msec. Atrial flutter was successfully converted to sinus rhythm by transesophageal pacing in 82% of patients. In 38% of patients, atrial flutter was converted directly to sinus rhythm without another intervening arrhythmia (direct conversion). The mean pacing rate required for direct conversion was 341 +/- 27 beats/minute. In 44% of patients, the cycle length of atrial flutter was accelerated to less than 180 msec or was converted to atrial fibrillation with spontaneous conversion to sinus rhythm within 24 hours (mean 8.4 +/- 9.3 hours, indirect conversion). The mean pacing rate inducing accelerated atrial flutter or transient atrial fibrillation was 372 +/- 61 beats/minute (p = NS compared to direct conversion). Atrial flutter was not interrupted or atrial fibrillation was induced that did not spontaneously convert to sinus rhythm within 24 hours in an additional seven patients (18%). The underlying cardiac disease, age, previous drug therapy, atrial size, atrial flutter cycle length, history of prior atrial fibrillation, left ventricular function, and concomitant medical illnesses did not predict the efficacy of transesophageal pacing. CONCLUSION: The present study suggests that transesophageal pacing is highly effective for interrupting spontaneous atrial flutter that does not terminate with standard antiarrhythmic drug therapy.
Adult↗
[Drug therapy of atrial fibrillation].
The authors summarize the up-to-date knowledge relating to the pharmacological treatment of atrial fibrillation. They emphasize that drug treatment continues to be in the forefront of the therapy of the arrhythmia, which can now be considered to constitute a cardiovascular epidemic. In the era following the Atrial Fibrillation Follow-up Investigation of Rhythm Management (AF-FIRM) trial, the strategy of pharmacological treatment will certainly change: in place of "rhythm control", which in recent decades has been overforced in patients identical with the elderly, cardiac patients with an impaired left ventricular function who were enrolled into AFFIRM, there will be a more frequent use of ventricular "rate control". Naturally, this does not mean that, in certain patient groups, an effort should not be made to restore and maintain the sinus rhythm. In cases involving congestive heart failure and structural heart disease complicated by a depressed left ventricular systolic function, atrial fibrillation is currently treated with antiarrhythmic drugs possessing low proarrhythmic activity that prolong refractory period (Class 3), and with the even safer mortality-reducing beta-receptor blockers. The classical antiarrhythmic drugs (quinidine, procainamide, disopyramide) are being increasingly forced into the background, and the areas of indication of the novel Na(+)-channel blocker antiarrhythmics (propafenone, flecainide) have also narrowed: they are administered only in the event of atrial fibrillation in patients with a structurally intact heart or left ventricular hypertrophy. After a brief survey of the more important aspects of ventricular rate control, and of the drugs available, the research trends aimed at the progression of the pharmacological treatment of atrial fibrillation are outlined. The clinical introduction of procedures based on myocardial gene therapy is now a realistic therapeutic approach as concerns atrial fibrillation too.
Anti-Arrhythmia Agents↗
Primary left atrial fibrosarcoma.
An elderly female with refractory cardiovascular symptoms due to functional mitral stenosis secondary to a primary left atrial fibrosarcoma is described. The symptoms are often nonspecific and most of the patients present first time with hemodynamic compromise. A high index of suspicion is essential for the early diagnosis of these highly malignant cardiac tumors because of their rarity, a wide spectrum of nonspecific symptoms and poor survival.
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Nonobstructive membranes of the left atrial appendage cavity: report of three cases.
A membranous structure causing functional stenosis at the mouth of the left atrial appendage (LAA) has been reported. In this study we describe the presence of nonobstructive membranes traversing the cavity of the LAA found incidentally on transesophageal echocardiography (TEE).
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Cardiac rhythm and conduction in Duchenne's muscular dystrophy: a prospective study of 20 patients.
This study was designed to determine the types and prevalence of rhythm and conduction disturbances in Duchenne's muscular dystrophy, and examine the results in light of known morphologic abnormalities of the myocardium and the small coronary arteries, and in the context of left ventricular function, regional wall motion, mitral valve prolapse and left atrial size. The observed disorders of impulse and conduction extended from the sinus node to the His-Purkinje system. Rhythm disturbances included persistent and labile sinus tachycardia (gradual or abrupt), sinus arrhythmia, sinus pauses, atrial ectopic beats, atrial ectopic rhythm, junctional rhythm, atrial flutter and ventricular premature beats (uniform, multiform, bigeminal and repetitive). Disorders of conduction included abnormal intraatrial or interatrial conduction, Mobitz type I block, nonconducted atrial premature beats, short PR interval, right ventricular conduction delay and rightward axis compatible with left posterior fascicular block. The role of dystrophic involvement of specialized conduction tissues and of the small vessel coronary arteriopathy remains speculative, but mitral valve prolapse, left atrial size and left ventricular size, function and regional wall motion played no discernible part in the genesis of the rhythm and conduction disturbances. Except for end-stage atrial flutter, these disturbances were not clinically deleterious.
Adolescent↗
The relationship between the atrial systole-ventricular systole interval and left ventricular function.
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Animals↗
Total body water estimation and maternal cardiac systolic function assessment in normal and gestational hypertensive pregnant women.
BACKGROUND: The importance of establishing correlations between cardiac function (cardiac output and stroke volume) and total body water (TBW) content in normal and hypertensive pregnancy focuses primarily on their potential relevance in treatment. Total body water content and cardiac function were evaluated in 25 normotensive (N) and 22 gestational hypertensive (GH) pregnant women matched for age, gestational age, and pre-pregnancy body mass index (BMI) during the third trimester of gestation. MATERIAL/METHODS: Patients underwent maternal echocardiography, bioelectrical impedance analysis (BIA), and hematocrit (Hct) evaluation, and the water balance index (WBI), i.e. the ratio of total body water to hematocrit, was computed. Hematocrit showed significantly lower values in normal than in GH women (31.9+/-2.2% vs. 36.2+/-2.5%; p<0.001). RESULTS: There was no difference in TBW between the two groups. The WBI was higher in normal than in GH women (1.35+/-0.20 l.kg-1.m-2 vs. 1.19+/-0.18 l.kg-1.m-2; p<0.001). Normal subjects showed a higher stroke volume than GH patients (78.0+/-9.7 ml vs 67.9+/-10.2 ml; p=0.001). Atrial function was also higher in normal than in GH women (left atrial fractional area change: 57.4+/-5.1% vs. 42.5+/-7.5%; p<0.001). Correlation was found between stroke volume and WBI (r=0.93, p<0.0001). CONCLUSIONS: Maternal cardiac function and the water balance index are strongly related and might help in comprehending the mechanisms of adaptation in physiologic and hypertensive pregnancy.
Adaptation, Physiological↗
Functional bundle branch block: discordant response of right and left bundle branches to changes in heart rate.
Faster heart rates shorten refractoriness more in some tissues than in others. This study investigates whether faster heart rates shorten relative refractoriness more in the right than left bundle branch in humans. Premature atrial stimulation at 2 or more basic cycle lengths was performed in 314 patients with no evidence of atrioventricular conduction system disease. In 10 patients, both functional right and left bundle branch block (BBB) developed with premature atrial stimulation. Functional right BBB occurred at the longer basic cycle length, and functional left BBB at the shorter cycle length in 8 patients. In 2 patients functional right and functional left BBB were present at the same cycle length, but functional left BBB occurred at a shorter premature atrial coupling interval. For all patients, the mean functional right bundle branch relative refractoriness was 438 ms at a basic cycle length of 847 ms, and functional left bundle branch relative refractoriness was 357 ms at a cycle length of 622 ms (p less than 0.01). The HV interval was 45 +/- 15 ms at control and increased with functional left BBB to 77 +/- 19 ms (p less than 0.01), but not with functional right BBB. Thus, relative refractoriness of the right and left bundle branches are rate-dependent and discordant. At longer cycle lengths, relative refractoriness of the right bundle branch is greater than that of the left bundle branch, and at shorter cycle lengths relative refractoriness of the left bundle branch is greater than that of the right bundle branch. The relative refractory period curves "cross over" and can explain the presence of both functional right and left BBB in the same patient.
Adolescent↗