Biatrial arrhythmogenic substrate in patients with hypertrophic obstructive cardiomyopathy

BACKGROUND

Atrial fibrillation (AF) in patients with hypertrophic obstructive cardiomyopathy (HOCM) may be caused by a primary atrial myopathy. Whether HOCM-related atrial myopathy affects mainly electrophysiological properties of the left atrium (LA) or also the right atrium (RA) has never been investigated.

OBJECTIVE

The purpose of this study was to characterize atrial conduction and explore differences in the prevalence of conduction disorders, potential fractionation, and low-voltage areas (LVAs) between the RA and LA during sinus rhythm (SR) as indicators of potential arrhythmogenic areas.

METHODS

Intraoperative epicardial mapping of both atria during SR was performed in 15 HOCM patients (age 50 ± 12 years). Conduction delay (CD) and conductin block (CB), unipolar potential characteristics (voltages, fractionation), and LVA were quantified.

RESULTS

Conduction disorders and LVA were found scattered throughout both atria in all patients and did not differ between the RA and LA (CD: 2.9% [1.9%-3.6%] vs 2.6% [2.1%-6.4%], P = .541; CB: 1.7% [0.9%-3.1%] vs 1.5% [0.5%-2.8%], P = .600; LVA: 4.7% [1.6%-7.7%] vs 2.9% [2.1%-7.1%], P = .793). Compared to the RA, unipolar voltages of single potentials (SPs) and fractionated potentials (FPs) were higher in the LA (SP: P75 7.3 mV vs 10.9 mV; FP: P75 2.0 mV vs 3.7 mV). FP contained low-voltage components in only 18% of all LA sites compared to 36% of all RA sites.

CONCLUSION

In patients with HOCM, conduction disorders, LVA, and FP are equally present in both atria, supporting the hypothesis of a primary atrial myopathy. Conceptually, the presence of a biatrial substrate and high-voltage FP may contribute to failure of ablative therapy of atrial tachyarrhythmias in this population.

Biomechanical response of ultrathin slices of hypertrophic cardiomyopathy tissue to myosin modulator mavacamten

Hypertrophic cardiomyopathy (HCM) is the most common inherited myocardial disorder of the heart, but effective treatment options remain limited. Mavacamten, a direct myosin modulator, has been presented as novel pharmacological therapy for HCM. The aim of this study was to analyze the biomechanical response of HCM tissue to Mavacamten using living myocardial slices (LMS). LMS (n = 58) from patients with HCM (n = 10) were cultured under electromechanical stimulation, and Verapamil and Mavacamten were administered on consecutive days to evaluate their effects on cardiac biomechanics. Mavacamten and Verapamil reduced contractile force and dF/dt and increased time-to-relaxation in a similar manner. Yet, the time-to-peak of the cardiac contraction was prolonged after administration of Mavacamten (221.0 ms (208.8 - 236.3) vs. 237.7 (221.0 - 254.7), p = 0.004). In addition, Mavacamten prolonged the functional refractory period (FRP) (330 ms (304 - 351) vs. 355 ms (313 - 370), p = 0.023) and better preserved twitch force with increasing stimulation frequencies, compared to Verapamil. As such, Mavacamten reduced (hyper-)contractility and prolonged contraction duration of HCM LMS, suggesting a reduction in cardiac wall stress. Also, Mavacamten might protect against the development of ventricular tachyarrhythmias due to prolongation of the FRP, and improve toleration of tachycardia due to better preservation of twitch force at tachycardiac stimulation frequencies.

In-vivo Sino-Atrial Node Mapping in Children and Adults With Congenital Heart Disease

BACKGROUND

Sinus node dysfunction (SND) and atrial tachyarrhythmias frequently co-exist in the aging patient with congenital heart disease (CHD), even after surgical correction early in life. We examined differences in electrophysiological properties of the sino-atrial node (SAN) area between pediatric and adult patients with CHD.

METHODS

Epicardial mapping of the SAN was performed during sinus rhythm in 12 pediatric (0.6 [0.4-2.4] years) and 15 adult (47 [40-55] years) patients. Unipolar potentials were classified as single-, short or long double- and fractionated potentials. Unipolar voltage, relative R-to-S-amplitude ratio and duration of all potentials was calculated. Conduction velocity (CV) and the amount of conduction block (CB) was calculated.

RESULTS

SAN activity in pediatric patients was solely observed near the junction of the superior caval vein and the right atrium, while in adults SAN activity was observed even up to the middle part of the right atrium. Compared to pediatric patients, the SAN region of adults was characterized by lower CV, lower voltages, more CB and a higher degree of fractionation. At the earliest site of activation, single potentials from pediatrics consisted of broad monophasic S-waves with high amplitudes, while adults had smaller rS-potentials with longer duration which were more often fractionated.

CONCLUSIONS

Compared to pediatric patients, adults with uncorrected CHD have more inhomogeneous conduction and variations in preferential SAN exit site, which are presumable caused by aging related remodeling. Long-term follow-up of these patients is essential to demonstrate whether these changes are related to development of SND and also atrial tachyarrhythmias early in life.

Impact of sex on timing and clinical outcome of septal myectomy for obstructive hypertrophic cardiomyopathy

BACKGROUND

Sex disparities are common in hypertrophic cardiomyopathy (HCM). Previous research has shown that at time of myectomy, women are older, have greater impairment of diastolic function and more advanced cardiac remodeling. The clinical impact of these differences is unknown.

METHOD

This study included 162 HCM patients (61% men) who underwent septal myectomy. Time to treatment was calculated in relation to symptom onset and diagnosis. Pre- and post-operative echocardiographic data were collected. Sex differences were assessed at baseline and in time-to-event survival analyses for the composite endpoint of all-cause mortality, cardiac transplantation, re-intervention and aborted sudden cardiac death.

RESULTS

Women were generally older at time of myectomy (57 vs. 49 years, p < 0.01), with similar time to treatment as measured from symptom onset (2.3 [1.3-6.0] vs. 2.8 [1.1-5.3] years, p > 0.05), but a shorter time since diagnosis compared to men (2.6 [1.2-7.0] vs. 4.3 [2.4-8.3] years, p = 0.02). Mean wall thickness and left atrial diameter were the same for men and women, but were higher in women when correcting for body surface area (absolute: 20 vs. 19 mm, 48 vs 46 mm, p ≥ 0.05; corrected: 9.7 vs. 11.2 mm/m², 23.4 vs. 26.3 mm/m², p < 0.01). After 5.9 [3.0-9.1] years, 15% of men and 8% of women had reached the composite endpoint (p > 0.05).

CONCLUSION

In conclusion, although women present later in life and seem to have more advanced disease on echocardiography, time until myectomy was similar and clinical outcomes after myectomy are favourable for both men and women.

Protein Quality Control Activation and Microtubule Remodeling in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disorder. It is mainly caused by mutations in genes encoding sarcomere proteins. Mutant forms of these highly abundant proteins likely stress the protein quality control (PQC) system of cardiomyocytes. The PQC system, together with a functional microtubule network, maintains proteostasis. We compared left ventricular (LV) tissue of nine donors (controls) with 38 sarcomere mutation-positive (HCMSMP) and 14 sarcomere mutation-negative (HCMSMN) patients to define HCM and mutation-specific changes in PQC. Mutations in HCMSMP result in poison polypeptides or reduced protein levels (haploinsufficiency, HI). The main findings were 1) several key PQC players were more abundant in HCM compared to controls, 2) after correction for sex and age, stabilizing heat shock protein (HSP)B1, and refolding, HSPD1 and HSPA2 were increased in HCMSMP compared to controls, 3) α-tubulin and acetylated α-tubulin levels were higher in HCM compared to controls, especially in HCMHI, 4) myosin-binding protein-C (cMyBP-C) levels were inversely correlated with α-tubulin, and 5) α-tubulin levels correlated with acetylated α-tubulin and HSPs. Overall, carrying a mutation affects PQC and α-tubulin acetylation. The haploinsufficiency of cMyBP-C may trigger HSPs and α-tubulin acetylation. Our study indicates that proliferation of the microtubular network may represent a novel pathomechanism in cMyBP-C haploinsufficiency-mediated HCM.

Tetralogy of Fallot in the Current Era

Only few studies have reported long-term outcome of the transatrial-transpulmonary approach in the current era of management of tetralogy of Fallot (ToF). We investigated 15-year outcome of correction via a transatrial-transpulmonary approach in a large cohort of successive patients operated in the 21st century. All infant ToF patients undergoing transatrial-transpulmonary ToF correction between 2000 and 2015 were included (N = 177, 106 male, median follow-up 7.1 (interquartile range 3.0-10.9) years. Data regarding postoperative complications, reinterventions, development of atrial and ventricular arrhythmia, cardiac function, and survival were evaluated. Prior shunting was performed in 10 patients (6%). The transatrial-transpulmonary approach resulted in valve-sparing surgery in 57 patients (32%). Postoperative surgical complications included junctional ectopic tachycardia (N = 12, 7%), pericardial (N = 10, 6%) or pleural effusion (N = 7, 3%), chylothorax (N = 7, 4%), bleeding requiring reoperation (N = 4, 3%), and superficial wound infection (N = 1). Fifty-one patients underwent 68 reinterventions, mainly due to pulmonary restenosis (PS) (N = 57). ToF correction at age <2 months and double outlet or double-chambered right ventricle variants of the ToF spectrum were independent predictors for reintervention. Patients undergoing valve-sparing ToF correction had a significant longer PR-free survival than those with a transannular patch (8.5 [95% confidence interval 6.8-10.3] years vs 1.1 [95% confidence interval 0.8-1.5] years; P < 0.001). Overall mortality was 2.8%; mortality rates were higher in premature/dysmature newborns (0.7% vs 9.5%; P < 0.001). Although the 15-year outcome of the transatrial-transpulmonary approach in terms of postoperative complications and mortality rates is excellent, the high incidence of moderate and severe PR is worrisome. Valve-sparing surgery was associated with a substantially lower incidence of PR, yet was surgically not possible in the majority of patients.

Surgical correction of a coronary fistula between the left main coronary artery and the coronary sinus in a neonate

We present a rare case of a 6-day old female neonate with a particularly exceptional coronary anatomy encompassing a fistula between the left main coronary artery and the coronary sinus with steal phenomenon, mandating surgical correction. The condition is extremely rare with an estimated incidence of about 0.1-0.2%. We operated this girl early on to prevent ischaemic events and pulmonary overflow with future heart failure. Further, we discuss possible aetiology and pathophysiological mechanisms of coronary artery fistulae and steal phenomena. Depending on specific anatomic characteristics, an interventional approach may be an alternative for surgical closure; however, this was not possible in our case.

Long-term benefit of myectomy and anterior mitral leaflet extension in obstructive hypertrophic cardiomyopathy

Severely symptomatic patients with obstructive hypertrophic cardiomyopathy (HC) may benefit from surgical myectomy. In patients with enlarged mitral leaflets and mitral regurgitation, myectomy can be combined with anterior mitral leaflet extension (AMLE) to stiffen the midsegment of the leaflet. The aim of this study was to evaluate the long-term results of myectomy combined with AMLE in patients with obstructive HC. This prospective, observational, single-center cohort study included 98 patients (49 ± 14 years, 37% female) who underwent myectomy combined with AMLE from 1991 to 2012. End points included all-cause mortality and change in clinical and echocardiographic characteristics. Mortality was compared with age- and gender-matched patients with nonobstructive HC and subjects from the general population. Long-term follow-up was 8.3 ± 6.1 years. There was no operative mortality, and New York Heart Association class was reduced from 2.8 ± 0.5 to 1.3 ± 0.5 (p <0.001), left ventricular outflow tract gradient from 93 ± 25 to 9 ± 8 mm Hg (p <0.001), mitral valve regurgitation from grade 2.0 ± 0.9 to 0.5 ± 0.8 (p <0.001), and systolic anterior motion of the mitral valve from grade 2.4 ± 0.9 to 0.1 ± 0.3 (p <0.001). The 1-, 5-, 10-, and 15-year cumulative survival rates were 98%, 92%, 86%, and 83%, respectively, and did not differ from the general population (99%, 97%, 92%, and 85%, respectively, p = 0.3) or patients with nonobstructive HC (98%, 97%, 88%, and 83%, respectively, p = 0.8). In conclusion, in selected patients with obstructive HC, myectomy combined with AMLE is a low-risk surgical procedure. It results in long-term symptom relief and survival similar to the general population.

Clinical outcome and health-related quality of life after right-ventricular-outflow-tract reconstruction with an allograft conduit

OBJECTIVE

Allograft conduits are used for reconstruction of the right ventricular outflow tract in congenital heart malformations (biventricular repair) and autograft procedures. A retrospective evaluation of allograft reconstruction of the right-ventricular-outflow-tract reconstruction was conducted and a cross-sectional quality of life study was performed.

METHODS

Between August 1986 and March 2009, 509 allografts (435 pulmonary and 74 aortic) were implanted in 463 pediatric and adult patients (308 right-sided congenital heart malformations and 155 autograft procedures). Perioperative and follow-up data were collected and analyzed. Kaplan-Meier analyses were done for survival, valve-related re-operation, and valve-related events. Cox regression analysis was used for evaluation of potential risk factors. In addition, the Short Form-36 was presented to patients to assess the perceived quality of life. The results of the Short Form-36 were compared to age-adjusted Dutch population norms.

RESULTS

The mean age at allograft implantation was 19 years (1 week-66 years). Mean follow-up was 9 years (2 days-22 years). Forty-eight patients died during follow-up. Patient survival was 93% at 10 years and 88% at 15 years. A total of 63 re-operations were required for allograft dysfunction in 58 patients. Freedom from valve-related re-operation was 89% at 10 years and 81% at 15 years. Freedom from valve-related events was 86% at 10 years and 74% at 15 years. Younger patient age (p=0.007) and the use of an aortic allograft (p<0.001) were identified as independent risk factors for allograft re-operation. Patients between 14 and 40 years scored significantly lower on 'physical functioning' and 'general health' subscales than the general Dutch population, but scored better on the subscales 'emotional role functioning' and 'bodily pain'. Except for the subscale 'general health', on which patients within our study population scored lower, patients between 41 and 60 years had comparable average scores as the general Dutch population. The older patient group (61 years or older) had a better average score on the subscale 'bodily pain' and similar scores on other subscales with respect to the general Dutch population.

CONCLUSIONS

Right-ventricular-outflow-tract reconstruction with an allograft conduit can be performed with good patient survival, acceptable long-term allograft durability, and good perceived quality of life.

Relevance of colloid oncotic pressure regulation during neonatal and infant cardiopulmonary bypass: a prospective randomized study

OBJECTIVE

In neonatal and infant cardiac surgery with cardiopulmonary bypass (CPB), hemodilution with reduction of plasma albumin concentration and low colloid oncotic pressure (COP) are the main factors associated with tissue edema and postoperative weight gain. The aim of our study was to evaluate the influence of two different COP regulatory strategies on post-bypass body weight gain, fluid balance, and clinical outcomes.

METHODS

Seventy elective patients with body weight<10 kg underwent first-time cardiac surgery with CPB and were randomized into two groups. The standard COP group received 0.5 g kg(-1) of human albumin in the priming and, during CPB, albumin was added to maintain the COP>15 mmHg. In the high COP group, albumin concentration in the priming was 5% and, during CPB, the COP was maintained above 18 mmHg. All patients were monitored before, during and until 24h postoperatively. Data were collected on body weight gain, COP, albumin concentration, fluids transfusion, blood loss, urine production and laboratory results.

RESULTS

Patients' demographics and operative data were comparable. Although the high COP group had perioperatively significantly higher COP and albumin concentration than the standard COP group, no significant difference was found in the body weight gain. There were also no significant differences between the groups with respect to fluid balance, urine output and blood loss. However, the high COP group had significantly shorter postoperative duration of mechanical ventilation (10h vs 14 h, p=0.02) and lower plasma lactate concentration post operation (1.1 mmoll(-1) vs 1.4 mmoll(-1), p=0.046).

CONCLUSIONS

The COP regulatory strategy for neonatal and infant CPB, based upon the 5% concentration of albumin in the priming and a COP target of 18 mmHg during bypass, better preserves the plasma albumin concentration within the physiological range and stabilizes the colloid pressure than the standard strategy (0.5 gkg(-1) albumin in the priming and bypass COP target at 15 mmHg). Nevertheless, only the lower postoperative plasma lactate concentration and the shorter duration of mechanical ventilation in the high COP group indicated the potential clinical benefit of this new strategy.

Long term follow up after surgery in congenitally corrected transposition of the great arteries with a right ventricle in the systemic circulation

Aim of the study

To investigate the long-term outcome of surgical treatment for congenitally corrected transposition of the great arteries (CCTGA), in patients with biventricular repair with the right ventricle as systemic ventricle.

Methods

A total of 32 patients with CCTGA were operated between January 1972 and October 2008. These operations comprised 18 patients with a repair with a normal left ventricular outflow tract, 11 patients with a Rastelli repair of the left ventricle to the pulmonary artery and 3 patients with a cardiac transplantation.

Results

Excluding the cardiac transplantation patients, mean age at operation was 16 years (sd 15 years, range 1 week - 49 years). Median follow-up was 12 years (sd 10 years, range 7 days - 32 years). Survival obtained from Kaplan-Meier analysis at 20 years after surgery was 63% (CI 53-73%). For the non-Rastelli group these data at 20 years were 62% (CI 48-76%) and for the Rastelli group 67% (CI 51-83%). Freedom of reoperation at 20 years was 32% (CI 19-45%) in the overall group. In the non-Rastelli group the data at 20 years were 47% (CI 11-83%) and for the Rastelli group 21% (CI 0-54%) after almost 19 years.

Conclusions

Long term follow up confirms that surgery in CCTGA with the right ventricle as systemic ventricle has a suboptimal survival and limited freedom of reoperation. Death occurred mostly as a result of cardiac failure.

Alveolar recruitment strategy and PEEP improve oxygenation, dynamic compliance of respiratory system and end-expiratory lung volume in pediatric patients undergoing cardiac surgery for congenital heart disease

OBJECTIVE

Optimizing alveolar recruitment by alveolar recruitment strategy (ARS) and maintaining lung volume with adequate positive end-expiratory pressure (PEEP) allow preventing ventilator-induced lung injury (VILI). Knowing that PEEP has its most beneficial effects when dynamic compliance of respiratory system (Crs) is maximized, we hypothesize that the use of 8 cm H(2)O PEEP with ARS results in an increase in Crs and end-expiratory lung volume (EELV) compared to 8 cm H(2)O PEEP without ARS and to zero PEEP in pediatric patients undergoing cardiac surgery for congenital heart disease.

METHODS

Twenty consecutive children were studied. Three different ventilation strategies were applied to each patient in the following order: 0 cm H(2)O PEEP, 8 cm H(2)O PEEP without an ARS, and 8 cm H(2)O PEEP with a standardized ARS. At the end of each ventilation strategy, Crs, EELV, and arterial blood gases were measured.

RESULTS

EELV, Crs, and P(a)O(2)/FiO(2) ratio changed significantly (P < 0.001) with the application of 8 cm H2O + ARS. Mean P(a)CO(2)- PETCO(2) difference between 0 PEEP and 8 cm H2O PEEP + ARS was also significant (P < 0.05).

CONCLUSION

An alveolar recruitment strategy with relative high PEEP significantly improves Crs, oxygenation, P(a)CO(2)- PETCO(2) difference, and EELV in pediatric patients undergoing cardiac surgery for congenital heart disease.

Outcome after reoperation for atrioventricular septal defect repair

Results of surgical repair of atrioventricular septal defect (AVSD), both partial (PAVSD) and complete (CAVSD), have improved. However, reoperation is not uncommon. This report describes our experience in 59 patients who underwent reoperation after AVSD repair, between 1977 and 2008. Thirty-one patients had a PAVSD, 28 had a CAVSD. Mean interval between initial repair and reoperation was 10+/-11 years (PAVSD vs. CAVSD: 13+/-12 vs. 6+/-9 years, P=0.063). Reoperations were required for left atrioventricular valve regurgitation (LAVVR) in 53 patients (combined with right atrioventricular valve regurgitation in 10, atrial septal defect (ASD) in 11, ventricular septal defect (VSD) in 7, left ventricular outflow tract (LVOT) obstruction in 1, and aortic valve stenosis in 1), ASD in 3, and LVOT obstruction in 3. Valve repair was performed in 45 patients and replacement in 8. Repair techniques of the left-sided atrioventricular valve (LAVV) included cleft closure in 44 patients, commissuroplasty in 19, and annuloplasty in 1. Freedom from additional reoperation was 85%, and 80% at 5 and 15 years. Hospital mortality was 3%. Overall survival was 91%, and 86% after 5 and 15 years. The most common indication to undergo reoperation is LAVVR. Reoperation is safe and in the majority of cases, a durable repair of the LAVV can still be achieved.

Effects of cardiopulmonary bypass circuit reduction and residual volume salvage on allogeneic transfusion requirements in infants undergoing cardiac surgery

Cardiopulmonary bypass in children may cause severe hemodilution and can lead to excessive perioperative blood loss and high transfusion requirements. Minimization of cardiopulmonary bypass circuit and salvage of red blood cells from the residual volume after the procedure are widely utilized to reduce allogeneic transfusion. We evaluated the effectiveness of those measures introduced in infant cardiac surgery in our institution. This retrospective observational study included 148 consecutive infants between 1 and 12 months of age, with a body weight <10 kg, who underwent an elective cardiac operation between 1997 and 2005. Patients were divided into three groups defined by the circuit prime volume; 700 ml (Group 1), 450 ml (Group 2) and 330 ml (Group 3). In Group 1 residual volume after perfusion was discarded and in Groups 2 and 3 was processed in a cell saving device. Analyzed variables were: perioperative blood loss, transfusion of homologous blood products and cell salvage product, and hematology data. Reduction of the circuit volume significantly diminished use of red blood cell concentrates from 1.6 units to 0.8 units (P<0.0001), and fresh frozen plasma from 1.3 units to 0.4 units (P<0.0001). Utilization of the cell salvage product reduced significantly (P=0.023) the postoperative need for homologous blood transfusion. Therefore, both measures proved to be effective in reducing homologous blood transfusion in infant cardiac surgery.

Massive haemorrhage at resternotomy after stent implantation in ventriculo-pulmonary shunt after Norwood procedure

The ventriculo-pulmonary shunt in hypoplastic left heart syndrome has become an alternative to the arterio-pulmonary shunt. We present a patient with a severe stenosis in the ventriculo-pulmonary shunt at the proximal anastomosis, for which emergency balloon dilatation and stent implantation was performed. The location of the stent in the shunt, leaving only a thin compressed infundibular myocardium directly beneath the sternum, predisposed to massive haemorrhage at resternotomy for bidirectional Glenn procedure.

Emergency surgery due to haematoma in a case of left atrial myxoma

Atrial myxomas generally do not require urgent surgery. We report on a 78-year-old woman in whom transesophageal echography revealed a large left atrial myxoma. She acutely developed dyspnoea, tachypnoea, and forward failure necessating urgent surgery. The myxoma was surgically removed and showed a haematoma. The most likely reason for the deteriorating condition was acute enlargement of the myxoma due to intramyxomal haemorrhage. This case illustrates that the clinical condition of patients with symptomatic myxoma can deteriorate suddenly and require urgent surgical treatment.

Efficacy of an implantable cardioverter-defibrillator in a neonate with LQT3 associated arrhythmias

We present a case in which LQTS induced severe prenatal and neonatal arrhythmias. LQT3 was diagnosed (mutation R1623Q). Short-acting beta-blockers were ineffective as well as sotalol and mexiletine in preventing recurrent ventricular arrhythmias. An ICD was implanted at the age of 7 months (weight and length of the infant at implantation 6 kg and 60 cm respectively). Flecainide was prescribed in addition to the ICD implantation. After an appropriate shock the flecainide plasma levels were shown to be subtherapeutic. Readjustment of the flecainide dose resulted in adequate plasma levels. No further shocks occurred during a further 17 months follow-up period. The combination of an active can with a subcutaneous patch proved feasible, and lifesaving shocks occurred at 7 months after implantation.

Assessment of right ventricular fibrosis in different forms of pulmonary atresia with ventricular septal defect

BACKGROUND

In pulmonary atresia with ventricular septal defect (PA-VSD), the corrective surgical strategy aims to reduce the right ventricular (RV) overload and restore physiological pulmonary perfusion before the characteristic RV hypertrophy and fibrosis become irreversible.

OBJECTIVE

To assess RV fibrosis in different forms of PA-VSD.

METHODS

RV biopsies were obtained at corrective surgery from PA-VSD patients (n=14, mean age 2.5+/-1.2 years) with patent arterial duct (PAD group, n=6; mean age 1.7+/-0.5 years) or systemic-pulmonary collateral arteries (SPCA group, n=8; mean age 3.2+/-1.2 years) and from age-matched controls (control group, n=6; mean age 2.5+/-1.8 years). Myocardial expression patterns (messenger RNA [mRNA] and protein levels) of the extracellular matrix proteins (eg, fibronectin and collagens [subtype I alpha and III) were quantitatively analyzed in relation to myocardial cell hypertrophy.

RESULTS

Comparing the age of PA-VSD patients at surgery, the SPCA group was older than the PAD group (P=0.01). Expression analysis by reverse transcriptase polymerase chain reaction showed significantly higher mRNA levels in patients with PA-VSD for collagen III (PA-VSD versus controls; 0.9+/-0.2 versus 0.6+/-0.1, P=0.03) than in controls, whereas collagen I alpha and fibronectin mRNA levels did not differ. No differences were found between the PAD and SPCA groups. The myocyte cross sectional surface area showed enhanced myocyte hypertrophy in patients with PA-VSD compared with the control group (P=0.015), with no significant difference between the PAD and SPCA groups. Video image analysis of immunohistochemical staining corrected for hypertrophy revealed unchanged interstitial collagens and fibronectin levels in all groups. However, perivascular staining corrected for the vessel lumen area showed significantly lower total collagen levels in patients with PA-VSD than in the control group (3.2+/-1.2 versus 7.2+/-2.8, respectively; P=0.004).

CONCLUSIONS

The results indicate that the extracellular matrix support for the coronary blood vessels appears to be suboptimal in patients with PA-VSD. The staged surgical approach in the SPCA group (with a higher age at correction) did not result in an excessive accumulation of fibrosis markers in the RV myocardium.

Right ventricular collagen and fibronectin levels in patients with pulmonary atresia and ventricular septal defect

Pulmonary atresia (PA) with ventricular septal defect (VSD) is an extreme form of tetralogy of Fallot with characteristic right ventricular hypertrophy. To reduce the right ventricular overload, these children have to undergo staged corrective surgery to restore physiological pulmonary perfusion. We studied the degree of fibrosis by analysing the myocardial expression pattern (at mRNA and protein level) of the extracellular matrix proteins, collagen and fibronectin in biopsies taken at corrective surgery from 14 patients affected by PA,VSD. Expression analysis by RT-PCR showed significantly higher levels for collagen III (p = 0.03), whereas collagen Ialpha (p = 0.31) and fibronectin (p = 0.47) mRNA levels remained unaltered in PA, VSD patients as compared to age matched controls. Video image analysis of immunohistochemical staining showed unchanged interstitial levels for total collagen (p = 0.17) as well as for fibronectin (p = 0.13) in the patients with PA, VSD. However, peri-vascular staining for collagen (p < 0.01) and fibronectin (p = 0.02) represented as the peri-vascular stained area corrected for the vessel lumen area showed significantly decreased levels in the PA, VSD group as compared to controls. Our results indicate that the patients with PA, VSD have inadequate extracellular matrix support for their coronary blood vessels and perhaps due to an altered biosynthesis of collagen and fibronectin network.