Ventricular size and function assessed by cardiac MRI predict major adverse clinical outcomes late after tetralogy of Fallot repair

BACKGROUND

Factors associated with impaired clinical status in a cross-sectional study of patients with repaired tetralogy of Fallot (TOF) have been reported previously.

OBJECTIVES

To determine independent predictors of major adverse clinical outcomes late after TOF repair in the same cohort during follow-up evaluated by cardiac magnetic resonance (CMR).

METHODS

Clinical status at latest follow-up was ascertained in 88 patients (median time from TOF repair to baseline evaluation 20.7 years; median follow-up from baseline evaluation to most recent follow-up 4.2 years). Major adverse outcomes included (a) death; (b) sustained ventricular tachycardia; and (c) increase in NYHA class to grade III or IV.

RESULTS

22 major adverse outcomes occurred in 18 patients (20.5%): death in 4, sustained ventricular tachycardia in 8, and increase in NYHA class in 10. Multivariate analysis identified right ventricular (RV) end-diastolic volume Z >or=7 (odds ratio (OR) = 4.55, 95% confidence interval (CI) 1.10 to 18.8, p = 0.037) and left ventricular (LV) ejection fraction <55% (OR = 8.05, 95% CI 2.14 to 30.2, p = 0.002) as independent predictors of outcome with an area under the receiver operator characteristic curve of 0.850. LV ejection fraction could be replaced by RV ejection fraction <45% in the multivariate model. QRS duration >or=180 ms also predicted major adverse events but correlated with RV size.

CONCLUSIONS

In this cohort, severe RV dilatation and either LV or RV dysfunction assessed by CMR predicted major adverse clinical events. This information may guide risk stratification and therapeutic interventions.

Magnetic Resonance Imaging Analysis of Right Ventricular Pressure-Volume Loops

Background— The aims of this study were to validate MRI-derived right ventricular (RV) pressure-volume loops for assessment of RV myocardial contractility and then to apply this technique in patients with chronic RV pressure overload for assessment of myocardial contractility, ventricular pump function, and VA coupling.

Methods and Results— Flow-directed catheters were guided under MR fluoroscopy (1.5 T) into the RV for invasive pressure measurements. Simultaneously, ventricular volumes and myocardial mass were assessed from cine MRI. From sampled data, RV pressure-volume loops were constructed, and maximal ventricular elastance indexed to myocardial mass (E max_i ) was derived by use of a single-beat estimation method. This MRI method was first validated in vivo (6 swine), with conductance techniques used as reference. Bland-Altman test showed good agreement between methods (E max_i =5.1±0.5 versus 5.8±0.7 mm Hg · mL −1 · 100 g −1 , respectively; P =0.08). Subsequently, the MRI method was applied in 12 subjects: 6 control subjects and 6 patients with chronic RV pressure overload from pulmonary hypertension. In these patients, indexes of RV pump function (cardiac index), E max_i , and VA coupling (E max /E a ) were assessed. In patients with pulmonary hypertension, RV pump function was decreased (cardiac index, 2.2±0.5 versus 2.9±0.4 L · min −1 · m −2 ; P <0.01), myocardial contractility was enhanced (E max_I , 9.2±1.1 versus 5.0±0.9 mm Hg · mL −1 · 100 g −1 ; P <0.01), and VA coupling was inefficient (E max /E a , 1.1±0.3 versus 1.9±0.4; P <0.01) compared with control subjects.

Conclusions— RV myocardial contractility can be determined from MRI-derived pressure-volume loops. Chronic RV pressure overload was associated with reduced RV pump function despite enhanced RV myocardial contractility. The proposed MRI approach is a promising tool to assess RV contractility in the clinical setting.

Attenuation of acute hypoxic pulmonary vasoconstriction and hypoxic pulmonary hypertension in mice by inhibition of Rho-kinase

RhoA GTPase mediates a variety of cellular responses, including activation of the contractile apparatus, growth, and gene expression. Acute hypoxia activates RhoA and, in turn, its downstream effector, Rho-kinase, and previous studies in rats have suggested a role for Rho/Rho-kinase signaling in both acute and chronically hypoxic pulmonary vasoconstriction. We therefore hypothesized that activation of Rho/Rho-kinase in the pulmonary circulation of mice contributes to acute hypoxic pulmonary vasoconstriction and chronic hypoxia-induced pulmonary hypertension and vascular remodeling. In isolated, salt solution-perfused mouse lungs, acute administration of the Rho-kinase inhibitor Y-27632 (1 × 10−5 M) attenuated hypoxic vasoconstriction as well as that due to angiotensin II and KCl. Chronic treatment with Y-27632 (30 mg·kg−1·day−1) via subcutaneous osmotic pump decreased right ventricular systolic pressure, right ventricular hypertrophy, and neomuscularization of the distal pulmonary vasculature in mice exposed to hypobaric hypoxia for 14 days. Analysis of a small number of proximal pulmonary arteries suggested that Y-27632 treatment reduced the level of phospho-CPI-17, a Rho-kinase target, in hypoxic lungs. We also found that endothelial nitric oxide synthase protein in hypoxic lungs was augmented by Y-27632, suggesting that enhanced nitric oxide production might have played a role in the Y-27632-induced attenuation of chronically hypoxic pulmonary hypertension. In conclusion, Rho/Rho-kinase activation is important in the effects of both acute and chronic hypoxia on the pulmonary circulation of mice, possibly by contributing to both vasoconstriction and vascular remodeling.

Caveolin-1 null mice develop cardiac hypertrophy with hyperactivation of p42/44 MAP kinase in cardiac fibroblasts

Recently, development of a caveolin-1-deficient (Cav-1 null) mouse model has allowed the detailed analysis of caveolin-1's function in the context of a whole animal. Interestingly, we now report that the hearts of Cav-1 null mice are markedly abnormal, despite the fact that caveolin-1 is not expressed in cardiac myocytes. However, caveolin-1 is abundantly expressed in the nonmyocytic cells of the heart, i.e., cardiac fibroblasts and endothelia. Quantitative imaging studies of Cav-1 null hearts demonstrate a significantly enlarged right ventricular cavity and a thickened left ventricular wall with decreased systolic function. Histological analysis reveals myocyte hypertrophy with interstitial/perivascular fibrosis. Because caveolin-1 is thought to act as a negative regulator of the p42/44 MAP kinase cascade, we performed Western blot analysis with phospho-specific antibodies that only recognize activated ERK1/2. As predicted, the p42/44 MAP kinase cascade is hyperactivated in Cav-1 null heart tissue (i.e., interstitial fibrotic lesions) and isolated cardiac fibroblasts. In addition, endothelial and inducible nitric oxide synthase levels are dramatically upregulated. Thus loss of caveolin-1 expression drives p42/44 MAP kinase activation and cardiac hypertrophy.

Late Gadolinium Enhancement Cardiovascular Magnetic Resonance of the Systemic Right Ventricle in Adults With Previous Atrial Redirection Surgery for Transposition of the Great Arteries

Background— Patients treated for transposition of the great arteries by atrial redirection surgery have a right ventricle (RV) that sustains systemic pressures long term. Late RV dysfunction occurs in these patients; the reasons for this are unclear, but myocardial fibrosis may be important. Myocardial fibrosis can be visualized by late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR). We hypothesized that LGE would be present in the systemic RV and relate to adverse clinical features.

Methods and Results— We performed CMR on 36 consecutive adult patients (mean age, 27 years) after atrial redirection surgery for transposition of the great arteries. Late gadolinium RV enhancement was seen in 22 patients (61%) with various patterns. Patients with RV LGE were older (30 versus 22 years; P <0.001) and had increased RV end-systolic volume index (43 versus 35 mL/m 2 ; P =0.03), decreased RV ejection fraction (57% versus 62%; P =0.02), increased QRS duration (108 versus 97 ms; P =0.01), and increased QT dispersion (93 versus 71 ms; P =0.002). The extent of LGE correlated with age ( r =0.59, P <0.001) and QRS duration ( r =0.67, P <0.001) and inversely with RV ejection fraction ( r =−0.76, P <0.001). The incidence of documented arrhythmia and/or syncope (10 of 36) was significantly higher in the late gadolinium-positive group (9/22 versus 1/14; P =0.03).

Conclusions— LGE CMR suggestive of myocardial fibrosis occurs in the systemic RV of patients after atrial redirection surgery. The extent of LGE correlates with age, ventricular dysfunction, electrophysiological parameters, and clinical events, suggesting prognostic importance that merits further investigation.

The right ventricle in congenital heart disease

In patients with congenital heart disease the right ventricle (RV) may support the pulmonary (subpulmonary RV) or the systemic circulation (systemic RV). During the last 50 years evidence is accumulating that RV dysfunction develops in many of these patients and leads to considerable morbidity and mortality. Therefore RV function in certain groups of congenital heart disease patients needs close surveillance and timely and appropriate intervention to optimise outcomes. Despite major progress being made, assessing the RV either in the subpulmonary or the systemic circulation remains challenging, often requiring a multi-imaging approach and expertise (echocardiography, magnetic resonance imaging, nuclear and occasionally invasive assessment with angiography). This review discusses the implications of volume and pressure loading of the RV in the context of congenital heart disease and describes the most relevant imaging modalities for monitoring RV function.

Right-ventricular failure is associated with increased mitochondrial complex II activity and production of reactive oxygen species

OBJECTIVE

Reactive oxygen species (ROS) have been implicated in the progression of ventricular hypertrophy to congestive heart failure. However, the source of increased oxidative stress in cardiomyocytes remains unclear.

METHODS

Here we examined NADPH oxidase and mitochondria as sources of ventricular ROS production in a rat model of right-ventricular (RV) failure (CHF) induced by pulmonary arterial hypertension (PAH).

RESULTS

Western analysis showed increased expression of the catalytic subunit gp91(phox) of NADPH oxidase as well as its activator Rac1 in RV in CHF compared to non-failing myocardium (CON). In addition, analysis of mitochondrial respiratory chain complexes showed a selective increase in the expression of Complex II subunit B. Using lucigenin chemiluminescence, tissue homogenates showed increased NADPH oxidase and Complex II-dependent ROS production in failing RV, with no increase in the left ventricle. Functional analyses of isolated RV mitochondria showed an increase in Complex II activity as well as Complex II-associated ROS production in CHF vs CON. An increase in the reduction state of the mitochondrial Coenzyme Q in failing RV, together with increased expression of hypoxia-inducible factor 1 alpha, indicated conditions in CHF that strongly favor ROS production by mitochondria. Reduced ROS-scavenging capacity was indicated by decreased mRNA levels of superoxide dismutases. Oxidative stress in failing RV was indicated by a two-fold increase in the level of phospho-p38 mitogen-activated protein kinase and by immunohistochemical evidence of extensive protein nitration.

CONCLUSIONS

These data show that the development of PAH-induced RV heart failure is associated with an increased capacity for ROS production by NADPH oxidase as well as mitochondria. The selective increase in expression and activity of mitochondrial Complex II may be particularly important for ventricular ROS production in heart failure.

Thrombolysis or heparin therapy in massive pulmonary embolism with right ventricular dilation: results from a 128-patient monocenter registry

STUDY OBJECTIVES

To assess the potential benefit of thrombolysis in patients with massive pulmonary embolism (PE) with stable hemodynamics and right ventricular dysfunction.

DESIGN

Retrospective, cohort study.

SETTING

University-based, tertiary referral medical center.

PATIENTS

One hundred fifty-three consecutive patients with massive PE from January 1992 to December 1997 treated with heparin or thrombolysis.

MEASUREMENTS AND RESULTS

Massive PE was confirmed by perfusion lung scan or pulmonary angiography. Right ventricular dysfunction was assessed by echocardiography (right ventricular/left ventricular [RV/LV] diastolic diameter ratio > 0.6) in all patients. In order to study a homogeneous population, 64 patients treated with thrombolysis (group 1) were matched on baseline RV/LV diameter ratio to 64 patients treated with heparin (group 2). Perfusion lung scan was repeated at day 7 to day 10. Mean relative improvement in perfusion lung scans was higher in group 1 than group 2 (54% vs 42%, respectively). PE recurrences were the same in both groups (4.7%; n = 3). There were no bleeding complications and no deaths in group 2. Conversely, in group 1, 15.6% (n = 10) of patients suffered from bleeding (4.7%; n = 3 with intracranial bleeding) and 6.25% (n = 4) of them died.

CONCLUSIONS

The results of this monocenter registry do not support the indication for thrombolysis in patients suffering from massive PE with stable hemodynamics and right ventricular dysfunction. Appropriate therapy in such patients still remains unknown. Further prospective randomized trials should be performed.

Gender differences in cardiac remodeling secondary to chronic volume overload

BACKGROUND

Gender differences in the prevalence of cardiovascular disease, both clinical and experimental, led us to evaluate the influence of gender on ventricular remodeling induced by chronic volume overload.

METHODS AND RESULTS

Chronic volume overload was induced in male and female rats via infrarenal aortocaval fistula. Ventricular function was assessed 8 weeks after fistula surgery in surviving rats. Left ventricular, right ventricular, and lung weights were measured. Mortality in female rats was 10-fold less than in male rats after 8 weeks of volume overload. Both sexes had significant increases in left ventricular weights relative to controls (77% increase for female v 114% for male rats; P <.05). Corresponding increases were also observed in right ventricular weight (134% for female v 161% for male rats; P <.05). However, lung weight was significantly increased only in males. In contrast to males, female rats had no indications of congestive heart failure. Male rats had marked dilatation and increased compliance, whereas female rats had no significant change in left ventricular dilatation or compliance.

CONCLUSIONS

There are clear gender-specific differences in ventricular function, structural remodeling, and mortality induced by chronic volume overload in this model of heart failure.

Ionic current abnormalities associated with prolonged action potentials in cardiomyocytes from diseased human right ventricles

OBJECTIVES

This study was designed to determine whether ionic currents in right ventricular myocytes from explanted human transplant recipient hearts are related to right ventricular histopathology and function.

BACKGROUND

Cardiac action potential duration (APD) is prolonged in ventricular tissues/cells from patients with heart failure, but the ionic mechanisms are not well documented.

METHODS

Membrane currents and transmembrane action potentials in myocytes from right ventricular epicardium of explanted human hearts were recorded using whole-cell patch clamp technique. Data from cells from right ventricles with severe histologic and functional abnormalities (abnormal histology group [AH]) and from right ventricles with preserved histology and function (relatively normal histology group [RNH]) were compared.

RESULTS

We found that APD at 50% (APD(50)) and 90% repolarization (APD(90)) were significantly longer in AH cells than in RNH cells. Early afterdepolarizations (EADs) were observed in 20% of AH cells and none of the RNH cells. Inwardly rectifying K(+) current (I(K1)) was decreased (both inward and outward components). Both transient outward K(+) current (I(to1)) and slowly delayed rectifier K(+) current (I(Ks)) were down-regulated in AH cells. L-type Ca(2+) (I(Ca.L)) was not altered in AH cells.

CONCLUSIONS

I(K1), I(to1), and I(Ks) are down-regulated in AH cells of human heart failure. This down-regulation contributes to APD prolongation that favors the occurrence of arrhythmogenic EADs and suggests a link between human cardiac histopathologic/functional abnormalities and arrhythmogenic ionic remodeling.

Histopathology of the right ventricular outflow tract and its relationship to clinical outcomes and arrhythmias in patients with tetralogy of Fallot

OBJECTIVES

The purposes of this study were to evaluate the myocardial histopathology and ultrastructure in patients with tetralogy of Fallot and to identify the histopathologic characteristics that may predispose patients to postoperative myocardial dysfunction and arrhythmias.

PATIENTS AND METHODS

Operatively resected crista supraventricularis muscle from 183 patients undergoing intracardiac repair of tetralogy of Fallot aged 12 months to 42 years (mean, 106.84 +/- 79.35 months) were studied by light and electron microscopy. Biventricular function and cardiac rhythm were assessed by 2-dimensional echocardiography and electrocardiography.

RESULTS

The incidence of moderate or severe cellular hypertrophy, endocardial thickening, and interstitial fibrosis was 36%, 68.3%, and 65%, respectively. Logistic regression analysis demonstrated age greater than 4 years, systemic arterial desaturation, higher hematocrit values, and elevated ventricular end-diastolic pressures as the major predisposing risk factors for pathologic changes. Twenty-seven (81.8%) patients more than 15 years of age and 29 (29.3%) patients between 4 and 15 years of age had predominant right ventricular dysfunction and low cardiac output (chi(2) [1 degree of freedom (df)] = 27.95; P < .001; odds ratio [OR] = 10.86 [3.75-33.10]). Ventricular arrhythmia was detected in 11 patients in whom repair was performed between 4 and 15 years of age and in 13 patients whose age at operation was 15 years or older. According to an additive logistic model, the effect of age at repair on the influence of ventricular arrhythmia was significant (chi(2) [1 df] = 24.4; P < .001; OR = 8.21 (2.96-23.11]).

CONCLUSIONS

The great majority of myocardial tissues in cyanotic tetralogy of Fallot indicates pre-existing ultrastructural hypertrophic and degenerative changes. The changes are more pronounced in older patients subjected to long-standing cyanosis and pressure overload and may account for or may coexist with the higher incidence of myocardial dysfunction and ventricular arrhythmia.

Arrhythmogenic right ventricular cardiomyopathy in young versus adult patients: similarities and differences

OBJECTIVES

This study was designed to evaluate and compare the patterns of arrhythmogenic right ventricular cardiomyopathy in young people and adults.

BACKGROUND

Few data are available on this cardiomyopathy in young people because clinical and morphologic findings considered pathognomonic are normally based on observations in adults. However, a familial occurrence with a probable genetic transmission led to the study of children and to early detection of this disease, in which sudden death has been reported even in young people.

METHODS

Seventeen young patients with arrhythmogenic right ventricular cardiomyopathy diagnosed at a mean age +/- SD of 14.9 +/- 4.9 years were studied. Clinical, electrocardiographic, echocardiographic, cineangiographic and biopsy findings were compared with those of 19 adult patients whose condition was diagnosed at a mean age of 38.1 +/- 13.4 years.

RESULTS

Syncope occurred in 23.5% of the young patients but in none of the adults (odds ratio of familial sudden death 5.54, p = 0.1). Ventricular couplets (odds ratio 16.0, p = 0.004) and subtricuspid bulging on echocardiography (odds ratio 5.95, p = 0.036) were prevalent in the young group. Cineangiographic data in the two groups were similar, except that more hypokinetic areas were found in adults (odds ratio 4.44, p = 0.05). Morphometric analysis of biopsy sections showed a greater amount of fibrous tissue in the young patients (p = 0.04) and a prevalence of fatty tissue in the adults (odds ratio 12, p = 0.005). During an equivalent follow-up time (mean 7 years), two young patients died suddenly, and two had ventricular fibrillation in the absence of antiarrhythmic therapy.

CONCLUSIONS

The pathognomonic criteria for the diagnosis of arrhythmogenic right ventricular cardiomyopathy in adults are also valid for young people. Sudden or aborted death occurred frequently in young untreated patients.

Cardiac inflammation contributes to right ventricular dysfunction following experimental pulmonary embolism in rats

Acute right ventricular (RV) failure following pulmonary embolism (PE) is a strong predictor of poor clinical outcome. Present studies test for an association between RV failure from experimental PE, inflammation, and upregulated chemokine expression. Additional experiments test if neutrophil influx contributes to RV dysfunction. PE was induced in male rats by infusing 24 microm microspheres (right jugular vein) producing mild hypertension (1.3 million beads/100 g, PE1.3), or moderately severe hypertension (2.0 million beads/100 g, PE2.0). Additional rats served as vehicle sham (0.01% Tween 20, Veh). In vivo RV peak systolic pressures (RVPSP) increased significantly, and then declined following PE2.0 (51 +/- 1 mm Hg 2 h; 49 +/- 1, 6 h; 44 +/- 1, 18 h). RV generated pressure of isolated, perfused hearts was significantly reduced in PE2.0 compared with PE1.3 or Veh. MCP-1 protein (ELISA) was elevated 21-fold and myeloperoxidase activity 95-fold in RV of PE2.0 compared with Veh or PE1.3. CINC-1, CINC-2, MIP-2, MCP-1, and MIP-1alpha mRNA also increased in RV of PE2.0. Histological analysis revealed massive accumulation of neutrophils (selective esterase stain) and monocyte/macrophages (CD68, ED-1) in RV of PE2.0 hearts in regions of myocyte damage. Electron microscopy showed myocyte necrosis and phagocytosis by inflammatory cells. LV function was normal and did not show increased inflammation after PE2.0. Treatment with anti-PMN antibody reduced RV MPO activity and prevented RV dysfunction. Conclusions-PE with moderately severe pulmonary hypertension (PE2.0) resulted in selective RV dysfunction, which was associated with increased chemokine expression, and infiltration of both neutrophils and monocyte/macrophages, indicating that a robust immune response occurred with RV damage following experimental PE. Experimental agranulocytosis reduced RV, suggesting that neutrophil influx contributed to RV damage.

The septal motor of biventricular function

This paper describes the anatomic spiral arrangement of the cardiac interventricular septum that results in a twisting action that contributes to the forceful ejection of blood from both ventricles during systole. Right ventricular (RV) dysfunction seen in various clinical settings is discussed with reference to the septum and its mechanism of function. The role of the septum in the interdependence of ventricular function is described. The structure/function relationships of the septum are related to maintenance of its oblique fiber orientation and midline configuration; disruption of this spatial relationship is the lynchpin of the concept that 'left heart failure begets right heart failure.' The importance of recognizing how alterations in septal anatomy affect biventricular performance is related to improved understanding of the clinical manifestations of septal dysfunction, designing a management scheme, and determining how to prevent septal injury.

Diverse Contribution of Bone Marrow–Derived Cells to Vascular Remodeling Associated With Pulmonary Arterial Hypertension and Arterial Neointimal Formation

Background— Recent evidence suggests that bone marrow (BM)–derived cells may differentiate into vascular cells that participate in arterial repair and/or lesion formation. However, it remains uncertain whether BM-derived cells also can participate in vascular remodeling associated with pulmonary arterial hypertension.

Methods and Results— The BM of Sprague-Dawley rats was reconstituted with that of green fluorescent protein–transgenic rats. The BM-chimeric rats were injected intraperitoneally with 60 mg/kg monocrotaline after unilateral subpneumonectomy, and they concurrently underwent wire-mediated endovascular injury in femoral artery. After 28 days, they had elevated right ventricular systolic pressure (58.8±5.4 versus 20.4±2.4 mm Hg in sham-control; P <0.01). The pulmonary arterioles were markedly thickened, with an infiltration of green fluorescent protein–positive macrophages into the perivascular areas. The endothelium of pulmonary arterioles contained only a few green fluorescent protein–positive cells, and green fluorescent protein–positive cells were seldom detected as smooth muscle cells in the lesions of thickened pulmonary arterioles. In contrast, BM-derived smooth muscle–like cells could be readily detected in the thickened neointima and media of the wire-injured femoral artery. Moreover, intravenous injection of 1×10 8 BM cells from young rats had no beneficial effects on pulmonary hypertension, pulmonary arterial remodeling, or survival in the aged rats treated with monocrotaline plus unilateral subpneumonectomy. No injected BM cell was identified as an endothelial cell or a smooth muscle cell.

Conclusions— These results suggest that BM-derived cells can participate in arterial neointimal formation after mechanical injury, whereas they do not contribute substantially to pulmonary arterial remodeling associated with monocrotaline-induced pulmonary arterial hypertension in the pneumonectomized rats.

Localized right ventricular morphological abnormalities detected by electron-beam computed tomography represent arrhythmogenic substrates in patients with the Brugada syndrome

AIMS

This study was designed to determine, using electron-beam CT, whether there are morphological abnormalities in patients with the Brugada syndrome and to elucidate the relationship between those abnormalities and arrhythmogenesis.

METHODS AND RESULTS

Twenty-six consecutive patients with the Brugada syndrome and 23 age- and gender-matched control subjects (controls) were evaluated for morphological abnormalities using electron beam CT. Electron beam CT demonstrated morphological abnormalities of the right ventricle in 21 (81%) of 26 patients, but in only two (9%) of 23 controls. The sites of morphological abnormalities were the right ventricular outflow tract area in 17 patients and the inferior wall of the right ventricle in four patients. Of the seven patients with monoform premature ventricular contractions recorded only in the acute phase, four of the five patients with premature ventricular contractions from the right ventricular outflow tract area had morphological abnormalities in the right ventricular outflow tract area, and the other two patients with premature ventricular contractions from the inferior wall of the right ventricle had morphological abnormalities in the inferior wall of the right ventricle.

CONCLUSION

The sites of morphological abnormalities detected by electron beam CT in patients with the Brugada syndrome were related to the origins of premature ventricular contractions recorded only in the acute phase, which may trigger ventricular fibrillation. These morphological abnormalities may be related to arrhythmogenic substrates in patients with the Brugada syndrome.

Reduction of QRS duration after pulmonary valve replacement in adult Fallot patients is related to reduction of right ventricular volume

AIMS

Late after total correction, Fallot patients with a long QRS duration are prone to serious arrhythmias and sudden cardiac death. Pulmonary regurgitation is a common cause of right ventricular (RV) failure and QRS lengthening. We studied the effects of pulmonary valve replacement (PVR) on QRS duration and RV volume.

METHODS AND RESULTS

Twenty-six consecutive Fallot patients were evaluated both pre-operatively and 6-12 months post-operatively by cardiac magnetic resonance (CMR). In this study, we present the computer-assisted analysis of the standard 12-lead electrocardiograms closest in time to the CMR studies. For the whole group, QRS duration shortened by 6+/-8 ms, from 151+/-30 to 144+/-29 ms (P=0.002). QRS duration decreased in 18 of 26 patients by 10+/-6 ms, from 152+/-32 to 142+/-31 ms. QRS duration remained constant or increased slightly in eight of 26 patients by 3+/-3 ms, from 148+/-27 to 151+/-25 ms. CMR showed a decrease in RV end-diastolic volume from 305+/-87 to 210+/-62 mL (P=0.000004). QRS duration changes correlated with RV end-diastolic volume changes (r=0.54, P=0.01).

CONCLUSION

Our study shows that PVR reduces QRS duration. The amount of QRS reduction is related to the success of the operation, as expressed by the reduction in RV end-diastolic volume.

Strain imaging in morbid obesity: insights into subclinical ventricular dysfunction

BACKGROUND

Obesity has become an important health problem throughout the world. Early detection of cardiovascular abnormalities may be useful in the future for patient management. This study aimed to identify subclinical ventricular dysfunction in obese patients.

HYPOTHESIS

Morbid obesity is associated with ventricular dysfunction.

METHODS

Doppler echocardiogram was performed in 92 morbidly obese and in 31 healthy controls. Conventional echocardiography and tissue Doppler-based strain imaging were used to analyze ventricular function. Intra- and interobserver strain imaging variabilities were tested on 15 randomly selected cases.

RESULTS

Left ventricular (LV) global strain (22.5% ± 3.5 vs 24.4% ± 2.5, P<0.005) and right ventricular (RV) strain (25.8% ± 5.2 vs 28.2% ± 5.2, P<0.029) were lower in obese patients when compared with healthy controls. Echocardiographic parameters of diastolic function were also different from controls. LV strain correlated with LV mass, E/e' ratio, left atrial volume, and RV strain. At multivariate analysis, morbid obesity remained a significant determinant of global LV strain, independently of associated comorbidities.

CONCLUSIONS

These findings suggest that incipient biventricular dysfunction is present in morbidly obese patients when new echocardiographic indices are used to investigate ventricular function. In addition, strain imaging may provide a more accurate assessment of the ventricular function in obese patients.

Arrhythmogenic right ventricular dysplasia: MR features

Arrhythmogenic right ventricular dysplasia (ARVD) is a heart disease characterized by a total or partial fat replacement of the myocardium. A total of 30 patients were studied with a suspected diagnosis of ARVD. Clinical criteria used for evaluation of ARVD were: (a) ventricular origin arrhythmias with a left bundle branch block configuration, (b) T-wave inversion in the anterior precordial leads, (c) ventricular kinetic alterations observed using echocardiography and angiography and (d) cardiac failure when there are no pathologies attributable to other heart diseases. All patients had serial EKG and echocardiography tests. One third of patients underwent angiocardiography; 7 of 30 had Holter; 7 of 30 had exercise test just to evaluate the effectiveness of the anti-arrhythmic therapy. All patients underwent MRI examination. The following MRI criteria were used: (a) high-intensity areas indicating the fatty substitution of the myocardium, (b) ectasia of the right ventricular outflow tract, (c) dyskinetic bulges, (d) dilation of the right ventricle and (e) enlargement of the right atrium. The diagnosis of ARVD was classified as highly probable for patients manifesting at least three positive criteria, probable with two positive criteria, dubious with one and negative in the absence of all criteria. Highly probable diagnosis of ARVD was made in 8 patients, probable in 4, dubious in 7 and negative in 11. The MRI technique is very effective in the assessment of ARVD. The MRI criteria may be helpful in the diagnosis of this condition.

Right ventricular regional function using MR tagging: normals versus chronic pulmonary hypertension

Right ventricular (RV) regional function, in both normal and diseased states, is not well characterized. Using 1D MR myocardial tagging, RV and septal intramyocardial segmental shortening was noninvasively measured in ten healthy subjects and in seven patients with chronic pulmonary hypertension. The normal RV free wall regional shortening was not uniform. A pattern of increasing RV free wall short-axis shortening was found from the RV outflow tract to the RV apex, and a more complex pattern of RV free wall long-axis shortening was observed. Both regional short- and long-axis shortening were globally reduced in pulmonary hypertension patients, with the greatest decreases in the RV outflow tract and in the basal septal wall region. Regional RV function can be quantitatively evaluated using MR tagging to determine the impact of chronic pulmonary hypertension on RV performance.

ECG predictors of ventricular arrhythmias and biventricular size and wall mass in tetralogy of Fallot with pulmonary regurgitation

BACKGROUND

In patients with the tetralogy of Fallot, QRS prolongation predicts malignant ventricular arrhythmias. QRS prolongation may result from right ventricular dilatation. The relation of ECG markers to biventricular wall mass and volumes has not been assessed.

OBJECTIVE

To investigate the relations of surface ECG markers of depolarisation and repolarisation to right and left ventricular volume and biventricular wall mass.

METHODS

37 Fallot patients (mean (SD) age 17 (9) years) were studied 14 (8) years after surgical repair; 34 had important pulmonary regurgitation. Left and right ventricular size was assessed from tomographic magnetic resonance imaging (MRI), and the amount of pulmonary regurgitation by velocity mapping MRI. QT, QRS, and JT duration and interlead dispersion markers were derived from a standard 12 lead ECG.

RESULTS

Mean QRS duration was significantly prolonged (133 (31) v 91 (11) ms in controls), as were dispersion of QRS (36 (17) v 20 (6) ms), QT interval (87 (48) v 42 (20) ms), and JT interval (93 (48) v 42 (19) ms). Biventricular volumes were increased (right ventricular end diastolic volume, 129 (41) v 70 (9) ml/m(2); left ventricular end diastolic volume, 83 (16) v 69 (10) ml/m(2)), as was right ventricular wall mass (24 (7) v 17 (2) g/m(2)). QRS duration correlated best with right ventricular mass (r = 0.55, p < 0.01).

CONCLUSIONS

In patients operated on for tetralogy of Fallot and with pulmonary regurgitation, ECG predictors of ventricular arrhythmias are influenced by several mechanical factors that may occur simultaneously. These include increased right ventricular volume, but also increases in left ventricular volume and in right and left ventricular wall mass.

Borderline left ventricle

The first problem to solve when dealing with the topic 'borderline left ventricle' is to find the appropriate definition. Several parameters have been taken into consideration, either morphometric (diameter of the mitral valve, indexed mitral valve area, left ventricular inflow dimension, left ventricular cross-sectional area, ratio between the apex-to-base left ventricular dimension and right ventricular dimension, left ventricular long axis to heart long axis ratio, left ventricular end diastolic volume, left ventricular mass index, ratio of the right/left ventricular wall thickness, presence of endocardial fibroelastosis, cardiac apex not formed by the left ventricle, diameter of the ventriculo-aortic junction, diameter of the aortic valve annulus and indexed aortic root diameter) as well as functional (left ventricular ejection fraction, left ventricular end diastolic pressure, mean pulmonary artery pressure, direction of the blood flow in the ascending aorta and at the level of the patent ductus arteriosus). Pre-operative determination whether the left ventricle is adequate to sustain the systemic circulation, or it may became adequate with the available surgical approaches, and therefore a bi-ventricular type of repair is feasible, can be extremely difficult, particularly in the presence of a 'borderline left ventricle'. In the clinical practice pediatric cardiologists and cardiac surgeons are faced with the problem of the 'borderline left ventricle' in four different groups of congenital heart defects: (a) aortic valve stenosis, (b) aortic coarctation, with or without hypoplastic aortic arch, (c) hypoplastic left heart complex, (d) right ventricular pressure and/or volume overload. In all the above situations in the presence of a left ventricle smaller than normal a very exhaustive approach has been reviewed in the decision making process, taking in account the literature reports as well as the personal experience. In each patient with 'borderline left ventricle' the elements to be considered for the decision making process between uni- and bi-ventricular type of repair, or for less ideal options of management, are the following: morphometric and functional parameters, hemodynamic data, available surgical options, results of the personal and institutional experience.

A statistical model for quantification and prediction of cardiac remodelling: application to tetralogy of Fallot

Cardiac remodelling plays a crucial role in heart diseases. Analyzing how the heart grows and remodels over time can provide precious insights into pathological mechanisms, eventually resulting in quantitative metrics for disease evaluation and therapy planning. This study aims to quantify the regional impacts of valve regurgitation and heart growth upon the end-diastolic right ventricle (RV) in patients with tetralogy of Fallot, a severe congenital heart defect. The ultimate goal is to determine, among clinical variables, predictors for the RV shape from which a statistical model that predicts RV remodelling is built. Our approach relies on a forward model based on currents and a diffeomorphic surface registration algorithm to estimate an unbiased template. Local effects of RV regurgitation upon the RV shape were assessed with Principal Component Analysis (PCA) and cross-sectional multivariate design. A generative 3-D model of RV growth was then estimated using partial least squares (PLS) and canonical correlation analysis (CCA). Applied on a retrospective population of 49 patients, cross-effects between growth and pathology could be identified. Qualitatively, the statistical findings were found realistic by cardiologists. 10-fold cross-validation demonstrated a promising generalization and stability of the growth model. Compared to PCA regression, PLS was more compact, more precise and provided better predictions.