Left Ventricular Length Research Articles

Predictors of atrial fibrillation recurrence in patients with long-lasting atrial fibrillation

Limited data are available on the predictors of atrial fibrillation (AF) recurrence in patients with chronic AF. To evaluate potential clinical, echocardiographic and electrophysiological predictors of AF recurrence, after internal cardioversion for long-lasting AF. A total of 99 consecutive patients (63 men and 36 women, mean age 63.33+/-9.27 years) with long-standing AF (52.42+/-72.02 months) underwent internal cardioversion with a catheter that consisted of two defibrillating coils. Shocks were delivered according to a step-up protocol. Clinical follow-up and electrocardiographic recordings were performed on a monthly basis for a 12-month period or whenever patients experienced symptoms suggestive of recurrent AF. Ninety-three patients (93.94%) underwent a successful uncomplicated cardioversion, with a mean atrial defibrillation threshold of 10.69+/-6.76 J. Immediate reinitiation of AF was observed in 15 patients (15.78%) of whom a repeated cardioversion restored sinus rhythm in 13 cases. Early recurrence of AF (within one week) was observed in 12 of 93 patients (12.90%). At the end of the 12-month follow-up period, during which seven patients were lost, 42 of the 86 remaining patients (48.84%) were still in sinus rhythm. Multivariate regression analysis showed that left atrial diameter (OR 1.126, 95% CI 1.015 to 1.249; P=0.025) and mitral A wave velocity (OR 0.972, 95% CI 0.945 to 0.999; P=0.044) were significant and independent predictors of AF recurrence, whereas age, left ventricular ejection fraction and AF cycle length were not predictive of arrhythmia recurrence. The present study showed that the left atrial diameter and mitral A wave velocity are the only variables associated with AF recurrence after successful cardioversion.

Clinical Significance of Left Ventricular Torsional Parameters during Supine Bicycle Cardiopulmonary Exercise Echocardiography

Introduction The Left ventricular (LV) torsion is a force generated between a counterclockwise rotation of the ventricular apex, and a clockwise rotation of the base. It plays an important role in both LV systolic and diastolic function, and it is now widely accepted that LV torsion is sensitive to changes in both regional and global LV function. Echocardiography offers a new way of assessing LV torsion for its non-invasiveness, and instant availability. Twodimensional (2D) echocardiography using the papillary muscle as landmarks, Doppler Tissue Imaging (DTI), and Speckle Tracking Imaging (STI) are being competitively evaluated, to become a promising non-invasive tool for LV torsion assessment. 2D-echocardiography, however, does not meet the original idea of torsion, for it only measures one level, rather than whole LV length. Moreover, DTI shows angle dependency and low spatial resolution. STI, on the other hand, seems to be given the edge in this compe-

Left ventricular long-axis function in treated haemochromatosis

We recently demonstrated reduced exercise capacity in treated genetic haemochromatosis, in spite of normal radial left ventricular (LV) systolic function assessed by 2-dimensional echocardiography at rest. It remains unknown if haemochromatosis-related impairment of LV long-axis function can be demonstrated also at rest. LV long-axis function was assessed by echocardiography including spectral tissue Doppler of systolic (S') and early (E') diastolic velocities in 105 treated haemochromatosis patients and 50 controls. Patients had higher body mass index, systolic atrioventricular excursion, and smaller LV end-systolic diameter (all P < 0.05). Other conventional echocardiographic variables did not differ. S' was normal in both groups, though significantly higher among the patients (11.1 vs. 9.9 cm/s, P < 0.001). In multiple regression analysis, higher S' was associated with having haemochromatosis, independently of significant contributions from higher atrioventricular excursion and LV length, and lower body mass index and E/E'-ratio (multiple R(2) = 0.44, P < 0.001). E' did not differ between patients and controls. However, in multivariate analysis lower E' was associated with having haemochromatosis independently of significant contributions from higher age and diastolic blood pressure, and lower transmitral E and end-diastolic LV length (multiple R(2) = 0.57, P < 0.001). The long-axis function in the haemochromatosis group was normal. Still haemochromatosis, even in this group of patients treated with regular phlebotomy, influenced both systolic and early diastolic long-axis function, and was associated with higher atrioventricular excursion and S', and with lower E'.

Abstract 707: Nonuniformity of Left Ventricular Apical-to-Basal Diastolic Lengthening in Patients with Hypertrophic Nonobstructive Cardiomyopathy

Quantification of left ventricular (LV) apex-to-base dispersion has been feasible with two-dimensional echocardiographic tissue tracking system (2DTT, Hitachi EUB7500), which based on pattern matching algorithm. Although impairment of LV relaxation was characterized in patients with hypertrophic cardiomyopathy (HCM), the behavior of LV apical and basal diastolic lengthening and its relation to LV filling are unknown. We obtained basal and apical LV short-axis views in 22 patients with non-obstructive HCM and 25 healthy volunteers (N). Eight equiangular points on endo-myocardium at end-diastole were placed in each view, and the shortening ratios of four directions were calculated and averaged by 2DTT. Then, the time-LV shortening and lengthening curves were obtained. The time intervals from the aortic valve closure to the point of the first 40% of peak lengthening (T 40 ) were measured in each view. Isovolumic relaxation time (IRT) was measured by pulsed Doppler LV in- and out-flow recordings. Although both apical and basal T 40 were similar in N (145.8±38.4 vs. 134.3±34.2msec 0.5 , ns.), the apical T 40 in HCM was longer compared to base (118.7±51.1 vs. 168.8±52.5msec 0.5 , p&lt;0.0001). The time difference of T 40 between apex and base was related to LV IRT (r=0.59, p&lt;0.0001). Nonuniformity of apical-to-basal left ventricular lengthening during early diastole was present in HCM. This apex-to-base dispersion, especially apical delay in timing of LV lengthening may have a physiologic importance for impairment of LV relaxation in HCM.

A multiplanar three dimensional echocardiographic study of mitral valvar annular function in children with normal and regurgitant valves

The mitral valvar complex is difficult to visualise accurately in only two dimensions. Three-dimensional echocardiography gives new insight into the dynamic changes of intra-cardiac structures during the cardiac cycle. The aim of this study was to study the mitral annulus in systole and diastole in normal children using three-dimensional echocardiography, and to analyse the effect of regurgitation on annular function. Three-dimensional echocardiographic datasets, acquired in 11 consecutive subjects with mitral regurgitation, and 20 normal subjects, were analysed offline using simultaneous multiplanar review. The mitral valvar annular area decreased in diastole, and increased in systole, in both groups. The annulus in patients with mitral regurgitation is dilated compared to normal subjects, the systolic value for those with regurgitation having a mean of 6.79 plus or minus 2.55 centimetres2/metres2, and the diastolic value a mean of 5.01 plus or minus 1.78 centimetres2/metres2, as opposed to a systolic mean value of 5.28 centimetres2/metres2 plus or minus 1.68, p = 0.091, and diastolic mean value of 3.05 centimetres2/metres2 plus or minus 0.90, in normal subjects (p less than 0.0001). The proportional change in mitral valvar annular area from systole to diastole showed a trend towards being smaller in those with mitral regurgitation, although this did not reach significance (24.8% versus 41.13%, p equal to 0.249). Analysis of subgroups of patients with moderate or severe mitral regurgitation showed mitral excursion, expressed as percentage of left ventricular length, to be significantly less than in normal subjects, at 12.78 plus or minus 5.10% versus 15.84 plus or minus 4.23% (p equal to 0.012). Mitral valvar annular area in children decreases in diastole, and increases in systole. In those with mitral regurgitation, the annulus is dilated and the dynamic annular function is depressed.

Impact of anaerobic glycolysis and oxidative substrate selection on contractile function and mechanical efficiency during moderate severity ischemia

The role of anaerobic glycolysis and oxidative substrate selection on contractile function and mechanical efficiency during moderate severity myocardial ischemia is unclear. We hypothesize that 1) preventing anaerobic glycolysis worsens contractile function and mechanical efficiency and 2) increasing glycolysis and glucose oxidation while inhibiting free fatty acid oxidation improves contractile function during ischemia. Experiments were performed in anesthetized pigs, with regional ischemia induced by a 60% decrease in left anterior descending coronary artery blood flow for 40 min. Three groups were studied: 1) no treatment, 2) inhibition of glycolysis with iodoacetate (IAA), or 3) hyperinsulinemia and hyperglycemia (HI + HG). Glucose and free fatty acid oxidation were measured using radioisotopes and anaerobic glycolysis from net lactate efflux and myocardial lactate content. Regional contractile power was assessed from left ventricular pressure and segment length in the anterior wall. We found that preventing anaerobic glycolysis with IAA during ischemia in the absence of alterations in free fatty acid and glucose oxidation did not adversely affect contractile function or mechanical efficiency during myocardial ischemia, suggesting that anaerobic glycolysis is not essential for maintaining residual contractile function. Increasing glycolysis and glucose oxidation with HI + HG inhibited free fatty acid oxidation and improved contractile function and mechanical efficiency. In conclusion, these results show a dissociation between myocardial function and anaerobic glycolysis during moderate severity ischemia in vivo, suggesting that metabolic therapies should not be aimed at inhibiting anaerobic glycolysis per se, but rather activating insulin signaling and/or enhancing carbohydrate oxidation and/or decreasing fatty acid oxidation.

Measurement of Left Ventricular Mass by Contrast Ventriculography

Elevated left ventricular mass (LVM) has been shown to be an important predictor of adverse cardiac events. Calculation of LVM using contrast ventriculography, as described by Rackley, involves measuring left ventricular wall thickness in a single plane, with assumptions made about ventricular geometry. We hypothesized that a modification of the Rackley method, involving multiple measurements of left ventricular (LV) wall thickness in 2 orthogonal planes, may add value in the determination of LVM in patients with LV remodeling and dysfunction. The LVM was determined in 24 patients with LV dysfunction who had undergone both cardiac magnetic resonance imaging (CMRI) and contrast left ventriculography. Right anterior oblique (RAO) and left anterior oblique (LAO) still frames in diastole were used to measure LV length, chamber area, and wall thickness. From these variables, LV volume, myocardial volume, and LVM were calculated. The LVM calculations using an average wall thickness from the LAO and RAO projections were compared with LVM measured by CMRI. Eighty eight percent of patients had hypertension, 100% had coronary artery disease, and mean left ventricular ejection fraction by contrast left ventriculography was 41 +/- 14%. Averaging left ventricular wall thickness from RAO and LAO projections using biplane ventriculography for LVM calculation yielded a strong correlation (r = 0.77, p < 0.01) with LVM calculated from CMR. In patients with left ventricular dysfunction, biplane left ventricular wall thickness measurements for contrast ventriculography LVM calculations render a strong correlation with LVM calculated by CMRI.

Echocardiographic predictors of mitral stenosis–related death or intervention in infants

The purpose of this study is to identify independent echocardiographic predictors of mitral stenosis (MS)-related death or intervention in infants. Congenital MS is a rare and morphologically heterogeneous lesion with variable prognosis. Among patients diagnosed with MS in early infancy, echocardiographic factors associated with MS-related intervention or death have not been determined. The clinical and echocardiographic data of patients diagnosed with MS at age <6 months by echocardiography between 1986 and 2004 were reviewed. The primary outcome was a composite end point of either mitral valve (MV) intervention (catheter or surgery) or death related to MS. Multiple variables from the initial echocardiogram were analyzed for association with outcomes. Seventy-one patients (median age at diagnosis 63 days) fulfilled the inclusion criteria. Multivariate analysis identified higher initial MV mean inflow gradient (P = .009) and lower left ventricular (LV) diastolic length Z-score (P = .006) at presentation as predictors of intervention or death. Among patients with an initial MV inflow gradient < 2 mm Hg, none reached an end point, whereas, among patients with an initial mean gradient >/= 5.5 mm Hg, the risk of intervention or death was 85%. Among patients with a gradient > 2 and < 5.5 mm Hg, an end point was reached in 38%, and an LV diastolic length Z-score </= 0 was predictive of outcome (71% vs 17%, P = .005). Mitral valve morphology was not predictive of outcome. In young infants with congenital MS, higher mean MV inflow gradient and shorter LV length, but not MV morphology, are associated with increased risk of MV intervention or MS-related death.

Longitudinal plane colour tissue-Doppler myocardial velocities and their association with left ventricular length, volume, and mass in humans

We investigated the relationships between colour tissue-Doppler parameters of left ventricular (LV) function and indices of LV morphology. LV length, end-diastolic volume, and mass were assessed in 40 healthy adult subjects. Further, colour tissue-Doppler scans assessed peak myocardial velocities during systole (S') and early diastole (E') as well as acceleration during isovolumic contraction (IVCa) at the mitral annulus. Non-linear allometric relationships (Y = aX(b)) were calculated to provide size exponents (b), with 95% confidence intervals, for tissue-Doppler variables (Y) and LV morphology parameters (X). The b exponents for LV length with Peaks S' and E' were not substantially different from unity (b = 0.87 and 0.95, respectively, P > 0.05). Peak E' was also associated with LV volume (b = 0.39, r = 0.53, P < 0.05). IVCa was not related to any LV morphology parameter. Peak S' or E' divided by LV length was confirmed as a valid size-independent scaling index. Conversely, IVCa is seemingly size independent.

Determining heart parameters through left ventricular automatic segmentation for heart disease diagnosis

Segmentation of the left ventricle in echocardiographic images is a task with important diagnostic power. This paper describes a method for the calculation of the ventricle’s contours in long- and short-axis views. The segmentation process starts with a complex border detection process, followed by the application of a generalized Hough transform to detect curves and ended up through an active-contour algorithm. Afterwards, parameters left ventricular area in a short-axis view, left ventricular length in a long-axis view, left ventricular volume, left ventricular mass, and heart-wall thickness are specifically calculated.

Determinants of Outcome in Fetal Pulmonary Valve Stenosis or Atresia With Intact Ventricular Septum

Pulmonary valve stenosis or atresia with intact ventricular septum represents a spectrum of severity. This study aimed to identify ultrasound markers of biventricular versus non-biventricular outcome. The fetal echocardiograms of 41 fetuses diagnosed with pulmonary stenosis or atresia and right ventricular (RV)/left ventricular (LV) length ratios >0.4 from 17 to 31 weeks of gestation were reviewed. Of 27 live-born patients with intention to treat, 8 had non-biventricular outcomes and 19 had biventricular circulation. At the time of diagnosis, poor RV function, flow reversal in the arterial duct, the degree of tricuspid valve (TV) regurgitation, and inferior vena cava Doppler flow pattern did not differ between the 2 outcome groups. However, RV sinusoids, the RV/LV length ratio, the TV/mitral valve ratio, and TV inflow duration were significantly different. Cut-off values derived from receiver-operating characteristic curves yielding the best sensitivity and specificity for a non-biventricular outcome were TV/mitral valve ratio <0.7, RV/LV length ratio <0.6, TV inflow duration <31.5% of cardiac cycle length, and the presence of RV sinusoids. If 3 of these 4 criteria were fulfilled, this predicted a non-biventricular outcome with sensitivity of 100% and specificity of 75%. In conclusion, in fetuses < or =31 weeks of gestation with pulmonary stenosis or atresia and intact ventricular septum, progression to a non-biventricular outcome can be predicted by a 4-criterion scoring system. The criteria may be useful in selecting fetuses for prenatal catheter intervention to prevent progressive RV hypoplasia.

Cardiovascular characterization of Pkd2 +/LacZ mice, an animal model for the autosomal dominant polycystic kidney disease type 2 (ADPKD2)

Background Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 or PKD2. Patients with ADPKD have an increased incidence of cardiac valve abnormalities and left ventricular hypertrophy. Systematic analyses of cardiovascular involvement have so far been performed only on genetically unclassified patients or on ADPKD1 patients, but not on genetically defined ADPKD2 patients. Even existing Pkd1 or Pkd2 mouse models were not thoroughly analyzed in this respect. Therefore, the aim of this project was the noninvasive functional cardiovascular characterization of a mouse model for ADPKD2. Methods Pkd2 +/LacZ mice and wildtype controls were classified into 8 groups with respect to gender, age and genotype. In addition, two subgroups of female mice were analyzed for cardiac function before and during advanced pregnancy. Doppler-echocardiographic as well as histological studies were performed. Results Doppler-echocardiography did not reveal significant cardiovascular changes. Heart rate and left ventricular (LV) length, LV mass, LV enddiastolic and LV endsystolic diameters did not differ significantly among the various groups when comparing wildtype and knockout mice. There were no significant differences except for a tendency towards higher maximal early and late flow velocities over the mitral valve in old wildtype mice. Conclusions Non-invasive phenotyping using ultrasound did not reveal significant cardiovascular difference between adult Pkd2 +/LacZ and WT mice. Due to the lack of an obvious renal phenotype in heterozygous mice, it is likely that in conventional ADPKD knock out mouse models severe cardiac problems appear too late to be identified during the reduced lifespan of the animals.

272 Can early diastolic left ventricular blood-to-tissue timing expose evidence of suction in the normal young heart?

Background and purpose: The presence of left ventricular (LV) diastolic suction constitutes old knowledge. However, even though frequently discussed, it has only rarely been elucidated with modern ultrasonic technique. Hypovolemia is thought to reveal evidence of suction (1). The high sampling rate/temporal resolution of both blood pooland tissue pulsed Doppler enables LV blood-to-tissue timing. With the stipulation that a preceding early diastolic LV tissue lengthening to the mitral inflow might indicate LV suction, we sought to investigate this at rest and during a preload reduction in normal individuals. Methods: Twelve healthy subjects (aged 28±4 years, 9 women) were examined with a Vivid 7, GE Medical Systems, including pulsed blood pooland tissue Doppler. The end-expiratory LV mean ‘E-e’ time interval (i.e. between the onsets of the mitral inflow (E) and the early diastolic LV lengthening (e), calculated with the R-wave of the ECG as a reference), the right ventricular (RV) early diastolic maximal velocity (e max), the mean LV e max, as well as the global isovolumic relaxation time (IVRT) were assessed at: horizontal rest, tilting to standing up (45‘) and lying back down. Results: With a presumed preload reduction (standing up), the LV IVRT increased (from 52±13 to 81±17 ms, p=0.006). The ‘E-e’ interval was slightly positive at rest (7±7 ms), but no change in E-e with a preload reduction became significant for all 12. However, two kinds of reactions might be distinguished. The onset of LV tissue lengthening was further antedated in relation to that of the mitral inflow in 9/12 individuals (from 8±8 to 25±11 ms, p=0.008). The remaining 3, who failed to exhibit this, displayed a greater fall in RV E max (-8.5±2.2 vs -3.0±2.7 cm/s, p=0.012), as well as in LV mean E max (-6.5±1.6 vs -3.5±1.5 cm/s, p=0.026) at standing up suggesting that a more pronounced preload reduction might have been induced. These 3 did not differ in height (174±4 vs 174±9 cm, p=NS), but had a lower BMI (18.9±1.0 vs 23.6±3, p=0.021) and also reported of a habitual orthostatic tendency. Conclusion: Our results even though not unambiguous may support evidence of LV suction in the normal heart, detectable through Doppler bloodto tissue timing. The different responses to a presumed preload reduction raises the question whether, still, an optimal volume level might be required for suction to be seen. 1. ‘Mitral annulus velocity at onset of filling a marker of diastolic suction’ Opdahl A, Remme EW, Helle-valle T, Edvardsen T, Vartdal T, Pettersen E, Ihlen H, Smiseth OA (e-poster at the ESC, 2006).

Echocardiographic Predictors of Outcome in Fetuses with Pulmonary Atresia with Intact Ventricular Septum

We sought to identify in utero predictors of postnatal outcomes in fetal patients with pulmonary atresia with intact ventricular septum (PAIVS) or critical pulmonary stenosis. Although PAIVS or critical pulmonary stenosis can be diagnosed in utero by echocardiography, our ability to predict outcomes is limited. Fetal echocardiograms from 28 patients with PAIVS/critical pulmonary stenosis were retrospectively reviewed. Tricuspid valve (TV) annulus, right and left ventricular internal dimensions, and degree of tricuspid regurgitation were recorded. To establish normal fetal values, echocardiograms from healthy patients were analyzed in an identical fashion. Both a fetal TV z score of -4 or less beyond 23 weeks of gestation and a fetal TV annulus of 5 mm or less beyond 30 weeks of gestation were predictive of poor postnatal outcomes. In addition, right:left ventricular length or width less than 0.5 and/or the absence of tricuspid regurgitation were predictive of poor outcome. TV annulus size, right:left ventricular ratios, and presence of tricuspid regurgitation on fetal echocardiograms may aid in guiding prenatal counseling regarding postnatal outcome in PAIVS.

Impact of Blockade of Histamine H2Receptors on Chronic Heart Failure Revealed by Retrospective and Prospective Randomized Studies

The goal of this work was to determine whether the blockade of histamine H2 receptors is beneficial for the pathophysiology of chronic heart failure (CHF). Because CHF is one of the major life-threatening diseases, we need to find a novel effective therapy. Intriguingly, our previous study, which predicts the involvement of histamine in CHF, suggests that we should test this hypothesis in patients with CHF. We selected 159 patients who received famotidine among symptomatic CHF patients for the retrospective study. We blindly selected age- and gender-matched CHF patients receiving drugs for gastritis other than histamine H2 receptor blockers as a control group. For the prospective study, 50 symptomatic CHF patients were randomly divided into 2 groups. One group received famotidine of 30 mg/day for 6 months, and the other group received teprenone. In the retrospective study, famotidine of 20 to 40 mg decreased both left ventricular end-diastolic and end-systolic lengths (LVDd and LVDs, respectively) and the plasma B-type natriuretic peptide (BNP) levels (182 +/- 21 vs. 259 +/- 25 pg/ml, p < 0.05) with unaltered fractional shortening (FS). In a randomized, open-label study, compared with teprenone, famotidine of 30 mg prospectively decreased both New York Heart Association functional class (p < 0.05) and plasma BNP levels (183 +/- 26 pg/ml vs. 285 +/- 41 pg/ml, p < 0.05); this corresponded to decreasing both LVDd (57 +/- 2 mm vs. 64 +/- 2 mm, p < 0.05) and LVDs (47 +/- 2 mm vs. 55 +/- 2 mm, p < 0.05) with unaltered FS (15 +/- 1% vs. 17 +/- 1%). The frequency of readmission because of worsening of CHF was lower in the famotidine group (4% and 24%, p < 0.05). On the other hand, teprenone had no effects on CHF. Famotidine improved both cardiac symptoms and ventricular remodeling associated with CHF. Histamine H2 receptor blockers may have therapeutic benefits for CHF.

Maturational and Adaptive Modulation of Left Ventricular Torsional Biomechanics

Left ventricular (LV) torsional deformation, based in part on the helical myocardial fiber architecture, is an important component of LV systolic and diastolic performance. However, there is no comprehensive study describing its normal development during childhood and adult life. Forty-five normal subjects (25 children and 20 adults; aged 9 days to 49 years; divided into 5 groups: infants, children, adolescents, and young and middle-age adults) underwent assessment of LV torsion and untwisting rate by Doppler tissue imaging. LV torsion increased with age, primarily owing to augmentation in basal clockwise rotation during childhood and apical counterclockwise rotation during adulthood. Although LV torsion and untwisting overall showed age-related increases, when normalized by LV length, they showed higher values in infancy and middle age. The proportion of untwisting during isovolumic relaxation was lowest in infancy, increased during childhood, and leveled off thereafter, whereas peak untwisting performance (peak untwisting velocity normalized by peak LV torsion) showed a decrease during adulthood. We have shown the maturational process of LV torsion in normal subjects. Net LV torsion increases gradually from infancy to adulthood, but the determinants of this were different in the 2 age groups. The smaller LV isovolumic untwisting recoil during infancy and its decline in adulthood may suggest mechanisms for alterations in diastolic function.

Differential effects of postconditioning on myocardial stunning and infarction: a study in conscious dogs and anesthetized rabbits

Postconditioning, i.e., brief intermittent episodes of myocardial ischemia-reperfusion performed at the onset of reperfusion, reduces infarct size after prolonged ischemia. Our goal was to determine whether postconditioning is protective against myocardial stunning. Accordingly, conscious chronically instrumented dogs (sonomicrometry, coronary balloon occluder) were subjected to a control sequence (10 min coronary artery occlusion, CAO, followed by coronary artery reperfusion, CAR) and a week apart to postconditioning with four cycles of brief CAR and CAO performed at completion of the 10 min CAO. Three postconditioning protocols were investigated, i.e., 15 s CAR/15 s CAO (n=5), 30 s CAR/30 s CAO (n=7), and 1 min CAR/1 min CAO (n=6). Left ventricular wall thickening was abolished during CAO and similarly reduced during subsequent stunning in control and postconditioning sequences (e.g., at 1 h CAR, 33+/-4 vs. 34+/-4%, 30+/-4 vs. 30+/-4%, and 33+/-4 vs. 32+/-4% for 15 s postconditioning, 30 s postconditioning, and 1 min postconditioning vs. corresponding control, respectively). We confirmed this result in anesthetized rabbits by demonstrating that shortening of left ventricular segment length was similarly depressed after 10 min CAO in control and postconditioning sequences (4 cycles of 30 s CAR/30 s CAO). In additional rabbits, the same postconditioning protocol significantly reduced infarct size after 30 min CAO and 3 h CAR (39+/-7%, n=6 vs. 56+/-4%, n=7 of the area at risk in postconditioning vs. control, respectively). Thus, contrasting to its beneficial effects on myocardial infarction, postconditioning does not protect against myocardial stunning in dogs and rabbits. Conversely, additional episodes of ischemia-reperfusion with postconditioning do not worsen myocardial stunning.

Fetal Aortic Valve Stenosis and the Evolution of Hypoplastic Left Heart Syndrome

Fetal aortic valvuloplasty may prevent progression of aortic stenosis (AS) to hypoplastic left heart syndrome (HLHS). Predicting which fetuses with AS will develop HLHS is essential to optimize patient selection for fetal intervention. The aim of this study was to define echocardiographic features associated with progression of midgestation fetal AS to HLHS. Fetal echocardiograms were reviewed from 43 fetuses diagnosed with AS and normal left ventricular (LV) length at < or =30 weeks' gestation. Of 23 live-born patients with available follow-up data, 17 had HLHS and 6 had a biventricular circulation. At the time of diagnosis, LV length, mitral valve, aortic valve, and ascending aortic diameter Z-scores did not differ between fetuses that ultimately developed HLHS and those that maintained a biventricular circulation postnatally. However, all of the fetuses that progressed to HLHS had retrograde flow in the transverse aortic arch (TAA), 88% had left-to-right flow across the foramen ovale, 91% had monophasic mitral inflow, and 94% had significant LV dysfunction. In contrast, all 6 fetuses with a biventricular circulation postnatally had antegrade flow in the TAA, biphasic mitral inflow, and normal LV function. With advancing gestation, growth arrest of left heart structures became evident in fetuses developing HLHS. In midgestation fetuses with AS and normal LV length, reversed flow in the TAA and foramen ovale, monophasic mitral inflow, and LV dysfunction are predictive of progression to HLHS. These physiological features may help refine patient selection for fetal intervention to prevent the progression of AS to HLHS.

Stress echocardiography in horses - a review

Summary The increasing number of publications in the field of equine stress echocardiography demonstrates the growing interest in this area. Stress echocardiography consists of B- and/or M-mode echocardiography under active or passive stimulation of the heart, where the pre-stimulation images are compared to those obtained during or immediately after stimulation. In human medicine, stress echocardiography is mainly used as a routine tool in diagnosis and prognosis of coronary artery disease, but also in the evaluation of hypertrophied and dilated cardiomyopathy and valvular diseases. In horses, the principal indications include the detection of exercised-induced myocardial insufficiency and refining the prognosis of low- and mid-grade valvular diseases. The two major cardiac stressors that can be used in horses are (1) physical exercise, which has the major disadvantage of a rapid decline in heart rate in the immediate post-exercise period and (2) pharmacological stimulation, which ideally consists of dobutamine infusion in combination of a parasympatholytic drug, in order to overcome the strong dobutamine-induced baroreceptor reflex in horses. Most stress echocardiographic studies performed in horses demonstrated a significant decrease of left ventricular length, diameter, area and volume in response to stimulation. Other studies also revealed a stimulation-induced increase in the interventricular septum, left ventricular free wall thickness, and left ventricular fractional shortening. Some of these changes seemed to be more pronounced during pharmacological stimulation than after exercise. One study described the application of a semi-quantitative wall motion scoring system in horses. Exercise as well as pharmacological stress echocardiography enhances the diagnostic possibilities in equine medicine, because it increases the chance to detect a problem that is not present at rest. Furthermore, this technique could help to investigate the relationship between valvular insufficiencies and ventricular dysfunction.

Biventricular repair in children with atrioventricular septal defects and a small right ventricle: Anatomic and surgical considerations

We sought to characterize morphology and to evaluate a strategy of using biventricular repair in patients with a small right ventricle and an unbalanced atrioventricular septal defect. Thirty-eight children with a small right ventricle and an atrioventricular septal defect underwent operative therapy. Thirty-two had biventricular repair, and 6 had single-ventricle palliation. A small right ventricle was defined on the basis of echocardiographic measurements expressed as the atrioventricular valve index (ie, right atrioventricular valve/left atrioventricular valve area) and as the ratio of right ventricular to left ventricular length. Validation of measurements in patients with a small right ventricle and an atrioventricular septal defect was achieved by comparison with balanced case-matched control subjects with atrioventricular septal defects. Children with a small right ventricle and an atrioventricular septal defect had a lower atrioventricular valve index (mean, 0.41 +/- 0.1 vs 0.52 +/- 0.1 [control], P < .0001) and lower right ventricular/left ventricular length ratio (0.78 +/- 0.1 vs 0.99 +/- 0.17 [control], P < .0001). Children with a small right ventricle undergoing single-ventricle palliation had the smallest right ventricular dimensions. There were 4 operative deaths. Three patients with a small right ventricle and an atrioventricular septal defect who underwent biventricular repair and had an atrioventricular valve index of less than 0.50 required early reoperation for right ventricular inadequacy. A restrictive atrial fenestration was created in 11 infants. Survival at 10 years was 87% for patients undergoing biventricular repair versus 100% for control subjects (P = .042). Extending the use of biventricular repair in properly selected patients with a small right ventricle and an atrioventricular septal defect is feasible. An atrial fenestration improves the physiologic tolerance to repair in selected patients. The use of biventricular repair in children with atrioventricular valve indexes of less than 0.50 requires caution.