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PubMed2002

Mother rotors and fibrillatory conduction: a mechanism of atrial fibrillation.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia and the major cardiac cause of stroke. Recent studies in patients with paroxysmal AF have shown that the arrhythmia is triggered by focal sources localized usually in one of the cardiac veins. However, in chronic AF, the prevailing theory is that multiple random wavelets of activation coexist to create an unorganized atrial rhythm. Experiments in isolated hearts have demonstrated that stable, self-sustained rotors can exist in the atria and that high frequency activation by such rotors results in the complex patterns of activation that characterize AF. Studies in animals and patients support the view that at least some cases of paroxysmal and chronic AF are the result of the uninterrupted periodic activity of discrete reentrant sites. In this brief review article, we examine historical data and more recent experimental evidence behind the hypothesis that AF may be organized by one, or a small number of high-frequency reentrant sources localized in the left atrium. We then discuss the potential implications and evidence supporting such a hypothesis for human AF. Finally, we suggest future studies designed to unravel the detailed molecular, cellular and pathophysiological mechanisms responsible for AF initiation and maintenance. The work discussed may open potentially exciting new diagnostic and therapeutic possibilities.

Acetylcholine↗
PubMed2005

QT-interval parameters are increased in systemic lupus erythematosus patients.

Systemic lupus erythematosus (SLE) patients have increased cardiovascular morbidity and mortality. QT-interval parameters are presumed markers of cardiovascular risk and have not been previously evaluated in SLE. Standard 12-lead ECGs were obtained from 140 female SLE outpatients and 37 age and body mass index-matched controls. QT interval was measured in each lead and heart rate-corrected maximum QT-interval duration (QTcmax) and QT-interval dispersion (QTd) were calculated. Risk factors for cardiovascular disease and lupus clinical features, disease treatment, disease activity and damage index were recorded. SLE patients have increased QT-interval parameters when compared to controls (QTcmax: 427.91 +/- 31.53 ms(1/2) versus 410.05 +/- 15.45 ms(1/2), P < 0.001; QTd: 52.38 +/- 22.21 ms versus 37.12 +/- 12.88 ms, P < 0.001). These differences persisted after excluding those patients with arterial hypertension, diabetes and with ECG abnormalities (QTcmax: 419.90 +/- 28.78 ms(1/2) versus 409.15 +/- 15.85 ms(1/2), P = 0.041; QTd: 54.74 +/- 26.00 ms versus 37.96 +/- 13.05 ms, P = 0.001). Multivariate linear regression for factors associated with QTcmax selected the presence of electrocardiographic left ventricular hypertrophy (ECG-LVH) (P = 0.003), nonspecific ST-T-wave abnormalities (P = 0.022) and left atrial enlargement (P = 0.044). Multivariate associates with QTd were age (P = 0.018), ECG-LVH (P = 0.022) and ST-T abnormalities (P = 0.031). In conclusion, SLE patients have increased QT interval parameters when compared to controls. This prolongation may lead to an increased cardiovascular risk. This finding might be due to subclinical atherosclerotic cardiovascular disease.

Adult↗
PubMed2006

Electrophysiological pulmonary vein antrum isolation with a multielectrode basket catheter is feasible and effective for curing paroxysmal atrial fibrillation: efficacy of minimally extensive pulmonary vein isolation.

BACKGROUND: How extensive should an appropriate pulmonary vein (PV) ablation be is a matter of controversy. OBJECTIVE: The study's aim was to investigate the efficacy of minimally extensive PV ablation for isolating the PV antrum (PVA) with the guidance of electrophysiological parameters. METHODS: Fifty-five consecutive symptomatic paroxysmal atrial fibrillation (PAF) patients underwent PV mapping with a multielectrode basket catheter (MBC). A 31-mm MBC was deployed in 3-4 PVs as proximally as possible without dislodgement, and the longitudinal PV mapping enabled us to recognize single sharp potentials formed by the total fusion of the PV and left atrial potentials around the PV ostium or the transverse activation patterns that were observed. Those potentials were defined as PVA potentials. Radiofrequency ablation was performed circumferentially targeting PVA potentials with the end point being their elimination. RESULTS: After circumferential PVA ablation, electrical disconnection was achieved in 77% and residual PVA conduction gaps were observed in 23% of all targeted PVs. Those residual conduction gaps were mainly located at the border between ipsilateral PVs (42%) and between the left PVs and left atrial appendage (33%) and were eliminated by a mean of 3 +/- 2 minutes of local radiofrequency deliveries. During the follow-up period (11 +/- 5 months), 46 (84%) patients were free of symptomatic PAF without any anti-arrhythmic drugs. No PV stenosis or spontaneous left atrial flutter occurred. CONCLUSIONS: Electrophysiological PVA ablation with an MBC is feasible and effective for curing PAF because this minimally extensive PVA isolation technique targets the optimal sites, achieving both high efficacy and safety.

Aged↗
PubMed1996

Noninvasive doppler echocardiographic evaluation of left ventricular filling pressures in patients with cardiomyopathies: a simultaneous Doppler echocardiographic and cardiac catheterization study.

OBJECTIVES: The purpose of this study was to examine the relation of the mitral flow velocity curves to left ventricular filling pressures in patients with two different types of myocardial problems: hypertrophic cardiomyopathy and severe left ventricular systolic dysfunction. BACKGROUND: Previous studies have suggested that assessment of Doppler-derived mitral flow velocity curves can be used to predict left ventricular filling pressures in specific disease entities. However, it is unclear whether information derived from specific mitral flow velocity curves obtained from one disease entity can be valid in other disease states. METHODS: The study group consisted of 42 patients with left ventricular systolic dysfunction (group A) and 55 patients with hypertrophic cardiomyopathy (group B); both groups underwent simultaneous cardiac catheterization and were studied by Doppler echocardiography. High fidelity measures of left atrial and left ventricular pressures were obtained simultaneously with mitral flow velocity curves. RESULTS: There was a significant relation between the Doppler echocardiographic variables and mean left atrial pressure in group A patients. The left atrial pressure was directly related to the E/A ratio (r = 0.49, p = 0.004) and inversely related to the deceleration time (r = 0.73, p < 0.001). The sensitivity and specificity of the deceleration time, < 180 m/s, which indicated a mean left atrial pressure > or = 20 mm Hg, were both 100%. In group B patients, there was no significant relation between mean left atrial pressure and deceleration time. CONCLUSIONS: Doppler echocardiographic mitral flow velocity curves are useful in predicting and estimating left ventricular filling pressures in patients with left ventricular dysfunction. However, because of the complexity of the multiple interrelated factors that determine diastolic filling of the left ventricle, these flow velocity curves cannot be used in patients with other disease entities, such as hypertrophic cardiomyopathy. Future studies of different disease states are necessary to fully understand the role of Doppler echocardiography in the assessment of diastolic filling.

Adult↗
PubMedDate not supplied

Reduction of adriamycin cardiotoxicity by enoximone.

Several non catecholamine, non glycoside cardiotonic drugs have been described recently. New compounds include amrinone, sulmazole, milrinone and pimobendan. In an attempt to alleviate or prevent anthracycline toxicity, we have reported that these compounds reduce the negative effects of adriamycin, 4-epiadriamycin and esorubicin in isolated guinea pig atria. The present study reports the effects of a new cardiotonic agent: enoximone. Enoximone was administered after adriamycin (100 micrograms/ml) on the isolated and spontaneously beating atria, and on electrically driven left atria of guinea pig-in normodynamic and hypodynamic conditions. Exposure for 60 minutes to the antitumor drug causes a depression of contractile force (g) and its derivative versus time (dF/dt, as maximal rate of contractile force). The negative effects of adriamycin are antagonised by enoximone (100, 200 micrograms/ml).

Animals↗
PubMed1999

A fluorometric assay for cyclic guanosine 3',5'-monophosphate incorporating a Sep-Pak cartridge and enzymatic cycling.

We developed a sensitive and nonradioactive fluorometric assay for cyclic guanosine 3',5'-monophosphate (cGMP). Guanine nucleotides except cGMP were enzymatically phosphorylated to GTP. cGMP, absorbed into a Sep-Pak amino propyl cartridge, was eluted separately from GTP. Purified cGMP was enzymatically converted to GTP, which was applied to the GTP-GDP cycle using succinic thiokinase and pyruvate kinase. When pyruvic acid produced by the GTP-GDP cycle was reduced by lactate dehydrogenase, a reduced form of nicotinamide adenine dinucleotide (NADH) was equivalently oxidized to NAD(+). NAD(+) was further converted into fluorescent compound, which was excited at 370 nm and emitted fluorescence at 460 nm, by a strong alkali. When 20 nmol NADH was used for this assay, the calibration curve over 50 to 500 fmol cGMP became sufficiently linear. The detection limit for cGMP was ca. 5 fmol (signal to noise ratio >3). Using this assay, we confirmed that the cGMP content in the left atrial strip of dog was changed from 11.4 +/- 3.8 to 19.3 +/- 2.6 fmol/mg wet wt of tissue (mean +/- SE, n = 6) by electrical driving at 1 Hz. Carbachol (1 microM) further increased the cGMP to 45.6 +/- 9.2 fmol/mg wet wt of tissue. From these results, it is suggested that this novel assay for cGMP is highly sensitive and can be applied to various biological samples.

Animals↗
PubMed1997

[Extrinsic compression of the left atrium as an infrequent and fatal form of type B aortic dissection: value of ECG].

We present an infrequent case of extrinsic compression of the left atrium caused by a type B aortic dissection diagnosed by echocardiography. The transthoracic echocardiography showed the obliteration of the left atrium by a heterogeneous mass with two circular images of low echogenicity. The TEE study identified the mass as a huge hematoma surrounding the true and false lumen of the aneurysm. The case demonstrated the value of echocardiography in the diagnosis of type B aortic dissection.

Aged↗
PubMed2006

[Percutaneous mitral commisurotomy in patients aged 60 years and more].

Of 745 patients treated by balloon mitral commissurotomy (BMC) between February 1988 and December 2002, 45 were > or = 60-years old. Immediate and late outcomes in this group (group 1) were compared with those in the patients aged < 60-years (group 2). Baseline hemodynamic parameters were comparable in the two groups. Mitral surface area and hemodynamic parameters improved significantly after BMC in group 1: mean left atrial pressure fell from 18.76 +/- 6.18 to 10.65 +/- 4.38 mmHg (P < 0.001), mean transmitral gradient from 11.03 +/- 4.70 to 4.63 +/- 2.05 mmHg (p < 0.001) and mitral valve area from 0.99 +/- 0.22 to 1.88 +/- 0.41 cm2 (p < 0.001). Similar significant improvements were seen in group 2. The hemodynamic result was good in 69% of group 1 patients. Tamponade occurred in one patient. Mitral regurgitation grade I or II developed in 8 patients and remained stable in 13 patients. These complication rates were comparable to those seen in group 2. In the group 1, a good result was maintained in 60% of patients after 43 +/- 23 months of follow-up. Although restenosis was observed in 40% of patients, functional amelioration was obtained in most of cases. In the group 2, restenosis was observed in 25% of patients. The data from this study suggest that BMC is effective first therapy in patients aged > or = 60-years with symptomatic mitral stenosis.

Adult↗
PubMed1997

Transatrial access for left atrial pressure monitoring in cardiac surgery patients.

We describe a simple method for left atrial pressure (LAP) monitoring from the right to the left atrium (LA) by a central line catheter. The anesthesiologist cannulates vena jugularis interna and inserts two central line catheters. One catheter is placed in the vena cava superior and the second single-lumen catheter is placed in the right atrium. The surgeon positions a one-line catheter from the right in the LA during the transatrial surgical procedure. This new access diminishes bleeding complications.

Atrial Function, Left↗
PubMed2005

Risk factors of posterior pericardial annuloplasty for isolated posterior leaflet prolapse.

BACKGROUND: Posterior autologous pericardial annuloplasty is an option in mitral valve repair. However, the durability of posterior pericardial annuloplasty remains controversial. METHODS: From June 1999 to July 2004, 49 patients (18 male and 31 female; mean age, 64 +/- 12 years) with isolated posterior leaflet prolapse received posterior autologous pericardial annuloplasty. Transthoracic echocardiographic examination before the operation, at the time of discharge, and then annually was performed and analyzed. RESULTS: There was no incidence of in-hospital or late death. Only 1 patient (2.1%) required reoperation. In terms of recurrent mitral regurgitation, 31 patients (64.6%) exhibited grade 0 mitral regurgitation, 7 patients (14.6%) exhibited grade 1, and 9 patients (18.8%) exhibited grade 2, whereas only 1 patient (2.0%) exhibited more than grade 3. In terms of predicting postoperative recurrence of significant mitral regurgitation (> or =grade 2), multivariate Cox analysis demonstrated that marked left atrial dilatation and high fractional shortening were independent risk factors. In 8 of 10 patients significant mitral regurgitation recurred after discharge. In terms of left atrial dimension, no significant reduction was observed in the postdischarge recurrent group, and there was a significant difference of left atrial dimension between the postdischarge recurrent group and the nonrecurrent group at the time of discharge. CONCLUSIONS: The merits of mitral valve repair using posterior autologous pericardial annuloplasty are attractive. However, its use should be limited in selected patients with isolated posterior leaflet disease, nonenlarged atria, and non-high fractional shortening to maintain the durability of the mitral valve repair.

Atrial Function, Left↗
PubMed1991

Hemodynamic alterations and regional myocardial blood flow during supraceliac aortic occlusion in dogs with a critical coronary stenosis.

The hemodynamic consequences and myocardial blood flow alterations associated with cross-clamping of the thoracic aorta were studied during pentobarbital (control), halothane (1 MAC), and isoflurane (1 MAC) anesthesia in dogs with a critical stenosis of the left circumflex coronary artery. Aortic clamping at the level of the diaphragm resulted in significant and equivalent increases in mean aortic pressure and left atrial pressure during the control clamp, halothane clamp, and isoflurane clamp periods. Likewise, aortic clamping resulted in a significant and equivalent decrease in cardiac output during control-clamp, halothane clamp, and isoflurane clamp. Myocardial contractility as assessed by dP/dt was depressed during halothane and isoflurane anesthesia when compared with control, but no further change in contractility was associated with aortic clamping. No significant alterations in regional or transmural myocardial blood flow were found with halothane or isoflurane anesthesia, or with aortic clamping during halothane or isoflurane anesthesia. It is concluded that there are significant hemodynamic consequences associated with aortic clamping, that neither halothane nor isoflurane anesthesia alters these consequences when compared with pentobarbital anesthesia alone, and that the deterioration in myocardial function observed during aortic clamping with halothane and isoflurane anesthesia cannot be attributed to any maldistribution of myocardial blood flow.

Anesthesia, Inhalation↗
PubMed1995

[Acute mitral valve insufficiency].

This type of disease has benefited considerably, over recent decades, from progress in ultrasound technique and new methods of medical and surgical treatment. The aetiologies of mitral incompetence can be classified into 4 categories according to their mechanism: 1. Mutilating valve lesions, usually secondary to bacterial endocarditis, but sometimes secondary to trauma (percutaneous valvuloplasty). 2. Rupture of chordae tendineae, either spontaneous or bacterial, in a context of pre-existing valvular heart disease, usually degenerative. 3. Papillary muscle lesions, usually corresponding to rupture of a papillary muscle or the head of a papillary muscle, associated with myocardial infarction. 4. Biological or mechanical valve prosthesis dysfunction. The consequences of acute mitral incompetence depend on its aetiology and the presence or absence of previous mitral valve disease. Three factors determine the clinical presentation and prognosis: the volume of regurgitation, left ventricular function and left atrial compliance. In pure forms, such as those occurring after rupture of chordae tendineae, the haemodynamic profile consists of a marked elevation of left ventricular filling pressures, left atrial mean and systolic pressures (large V wave), and a reduction of the cardiac output. The left ventricular end-diastolic volume is moderately increased, while the end-systolic volume is normal or decreased and the ejection fraction is increased. The clinical picture is that of acute left ventricular failure with a systolic murmur of mitral regurgitation and a pulmonary hypertension syndrome. The absence of left ventricular hypertrophy on the electrocardiogram and the absence of left-sided dilatation on radiological examination indicate the recent nature of the haemodynamic disturbances. The diagnosis of acute IM is confirmed by Doppler ultrasound, which defines the mechanism and sometimes eliminates the need for an invasive investigation. The clinical course depends on the aetiology, the volume of regurgitation, left ventricular function and the treatment implemented. First-line treatment must include vasodilators. Sodium nitroprussate infusion decreases the left ventricular end-diastolic volume and the volume of regurgitation and increases the cardiac output. It allows a rapid reduction of pulmonary artery and capillary hypertension. When this treatment is not sufficient, intra-aortic counterpulsation may be useful. Emergency surgery is sometimes necessary, but usually after improvement of the haemodynamic state by vasodilators. Depending on the aetiology, surgery may consist of valve replacement or surgical repair, which can give excellent results even in the presence of active bacterial endocarditis. In other cases, following control of the acute phase by medical treatment, mitral incompetence will become chronic.

Acute Disease↗
PubMed1998

Intrinsic neural regulation of the heart in the chronic, conscious dog.

The present experiments were performed to examine the capability of the intrinsic cardiac nerves (ICN) to modify cardiac performance in the resting chronic, conscious dog. Control and cardiac-denervated dogs were instrumented for recording of left atrial (LA) and ventricular (LV) contractility, heart rate, and atrioventricular (AV) conduction time. Acetylcholine (ACh) and nicotine (Nic) were administered via an indwelling coronary artery catheter. Limited distribution from the injection site only allowed access to the LA, LV, and AV node. Both beta-blockade with timolol and cardiac denervation were used to separate direct effects of ICN stimulation from indirect (e.g., reflex) effects. ACh produced the expected negative inotropic and dromotropic changes. ICN stimulation with Nic caused large decreases in LA on but only trivial effects on the LV. We concluded that the ICN has limited effects on cardiac performance in the resting animal under minimal sympathetic drive. It is likely, however, that the ICN is capable of significantly depressing cardiac function under conditions of elevated sympathetic tone as would be encountered in exercise.

Acetylcholine↗
PubMed1990

[Left atrial systolic time intervals: their relations to left atrial preload, afterload and acute left ventricular pressure loading].

Using pulsed Doppler echocardiography, the left atrial pre-ejection period (LAPEP) and left atrial ejection time (LAET) were studied in relation to left atrial loading and acute left ventricular pressure loading conditions in 17 patients with various heart diseases. LAPEP was defined as the time interval from the onset of a right atrial pacing pulse to the upstroke in the atrial contraction phase on the mitral flow velocity pattern; LAET was defined as the duration of left ventricular filling due to atrial contraction. 1. LAPEP did not correlate significantly with mean pulmonary capillary wedge pressure (mPCWP) indicating preload for the left atrium, nor with left ventricular end-diastolic pressure (LVEDP) indicating afterload for the left atrium. There were significant inverse correlations of LAET with mPCWP (r = -0.72) and with LVEDP (r = -0.75). 2. LAPEP, LAET and LAPEP/LAET correlated significantly with the ratio of the peak velocity in the atrial contraction phase and to that in the rapid filling phase (r = -0.62, -0.50 and -0.59, respectively). There was a significant inverse correlation of LAPEP/LAET with the left ventricular ejection fraction (r = -0.62). 3. When left ventricular systolic pressure became elevated by 25% of its basal value at a constant right atrial pacing rate, LAPEP decreased from 110 +/- 21 msec to 103 +/- 22 msec (p less than 0.05), LAET increased from 123 +/- 33 msec to 129 +/- 24 msec and LAPEP/LAET decreased from 0.95 +/- 0.37 to 0.84 +/- 0.32 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A dual-component positive inotropic effect of endothelin-1 in guinea pig left atria: a role of protein kinase C.

This study was designed to analyze the mechanism(s) underlying the positive inotropic effect (PIE) of endothelin-1 (ET-1) in the guinea pig left atrium. ET-1 exhibited a greater PIE at lower frequencies of pacing and potentiated significantly the postrest contraction similar to isoproterenol. However, ET-1 prolonged the duration of a single contraction, whereas isoproterenol shortened it. ET-1 was similar to methyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine-5- carboxylate in the prolonged duration of a single contraction but different from this drug in the force-frequency relationship. ET-1 at concentrations of 10 nM and higher caused a dual-component PIE composed of an initial increasing phase (early component) and a second greater positive inotropic phase (late component). The early component was correlated to the ET-1-induced prolongation of the duration of the action potential in the time course. Both nifedipine and ryanodine suppressed the late component much more than the early component. ET-1 (> or = 3 nM) produced significant stimulation of phosphoinositide hydrolysis as measured by [3H]inositol monophosphate accumulation. ET-1 was found to activate protein kinase C (PKC) instantaneously but transiently (evaluated by the translocation of PKC activity to the particulate fraction). Pretreatment with 1-(5-isoquinolinylsulfonyl)-2-methyl-piperazine and staurosporine, PKC inhibitors, markedly inhibited the late component of the PIE of ET-1 without affecting the early component. These data indicate that the two components of the PIE induced by ET-1 in the guinea pig left atrium may be mediated by different mechanisms. The early component may be attributed to the increased Ca++ influx as a result of the prolongation of the duration of the action potential, whereas the late component may be linked to stimulation of phosphoinositide hydrolysis and subsequent PKC activation.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1995

Standard orthotopic heart transplantation versus total orthotopic heart transplantation. A transesophageal echocardiography study of the incidence of left atrial thrombosis.

BACKGROUND: After standard orthotopic heart transplantation (Sd HT), the enlarged resultant atria may promote atrial thrombosis. The purpose of this study was to compare the incidence of spontaneous echo contrast and left atrial thrombosis after Sd HT and total orthotopic (Tot HT) heart transplantation. METHODS AND RESULTS: Transesophageal echocardiography (TEE) was performed in 75 patients with Sd HT and in 20 patients with Tot HT. Despite the use of antiplatelet therapy, an acute arterial embolism occurred in 11 (15%) of the 75 patients with Sd HT but in none of the 20 Tot HT patients. All patients were in sinus rhythm. Left ventricular ejection fraction was similar in Sd HT and Tot HT patients. Left atrial diameter was smaller in Tot HT patients than in Sd HT patients (41 +/- 4 versus 58 +/- 6 mm, P < .001). In Sd HT patients, spontaneous echo contrast was present in 43 patients (57%) and was associated with left atrial thrombus in 20 patients (on the left atrial appendage in 12 patients, on the posterior wall in 6, and on the suture in 2). No thrombus was detected by transthoracic echocardiography; all thrombi were detected by TEE. On the other hand, no left atrial thrombus was observed in Tot HT patients, and only 1 patient had spontaneous echo contrast. Of the 11 Sd HT patients who experienced an arterial embolism, 5 had both spontaneous echo contrast and left atrial thrombus and 5 had only spontaneous echo contrast. CONCLUSIONS: This study demonstrates a high rate of left atrial thrombus after Sd HT and emphasizes the role of TEE in the follow-up of these patients. The therapeutic implications are the need for a preventive anticoagulant therapy in the high-risk population receiving Sd HT diagnosed with TEE and the consideration of Tot HT as a better surgical approach as far as thrombotic complications are concerned.

Adult↗
PubMed1996

Successful percutaneous double balloon valvuloplasty for congenital mitral stenosis.

A 19-month-old infant had an isolated severe 'typical' congenital mitral stenosis with dysplastic valves and two symmetric papillary muscles. He underwent successful double balloon mitral valvuloplasty via the right femoral vein. Left atrium pressure decreased from 30 to 20 mmHg and end diastolic mitral gradient from 12 to 0 mmHg. Cardiac index increased from 4.4 to 6.3 l/min per m2. Gorlin's mitral valve area increased from 1 to 1.7 cm2/m2 and Doppler mitral valve area from 0.9 to 2.2 cm2/m2. At 16 months follow-up, the infant showed sustained clinical improvement.

Atrial Function, Left↗
PubMed2002

Prediction of left ventricular peak ejection velocity by preceding and prepreceding RR intervals in atrial fibrillation: a new method to adjust the influence between two intervals.

In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals (< or =0.5 sec) and plateau in long RR-1 intervals (> 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29+/-0.21 (p<0.001), when coordinates with RR-1 < or =0.5 sec were excluded. The RR-1 was positively associated with Vpe. The mean r2 between RR-1 and Vpe was 0.52+/-0.17 and improved to 0.72+/-0.11 (p<0.001), when adjusted by RR-2. Simple linear regression analysis showed that mean RR interval, age, fractional shortening (FS), and mean peak velocity were negatively correlated with modified r2 between RR-2 and Vpe. Multiple stepwise regression analysis revealed that mean RR interval (r2=0.32) and FS (r2=0.16) were significant. In summary, simple modification could improve the relationship of both RR-1 and RR-2 with cardiac performance. RR-2 might play a more role in cardiac performance than previously expected, and when cardiac function was impaired.

Aged↗