Systemic ventricular morphology-associated increased QRS duration compromises the ventricular mechano-electrical and energetic properties long-term after the Fontan operation

Impact and Modifiers of Ventricular Pacing in Patients With Single Ventricle Circulation

BACKGROUND

Palliation of the single ventricle (SV) circulation is associated with a burden of lifelong complications. Previous studies have identified that the need for a permanent ventricular pacing system (PPM_v) may be associated with additional adverse long-term outcomes.

OBJECTIVES

The goal of this study was to quantify the attributable risk of PPM_v in patients with SV, and to identify modifiable risk factors.

METHODS

This international study was sponsored by the Pediatric and Congenital Electrophysiology Society. Centers contributed baseline and longitudinal data for functionally SV patients with PPM_v. Enrollment was at implantation. Controls were matched 1:1 to PPM_v subjects by ventricular morphology and sex, identified within center, and enrolled at matched age. Primary outcome was transplantation or death.

RESULTS

In total, 236 PPM_v subjects and 213 matched controls were identified (22 centers, 9 countries). Median age at enrollment was 5.3 years (quartiles: 1.5-13.2 years), follow-up 6.9 years (3.4-11.6 years). Median percent ventricular pacing (Vp) was 90.8% (25th-75th percentile: 4.3%-100%) in the PPM_v cohort. Across 213 matched pairs, multivariable HR for death/transplant associated with PPM_v was 3.8 (95% CI 1.9-7.6; P < 0.001). Within the PPM_v population, higher Vp (HR: 1.009 per %; P = 0.009), higher QRS z-score (HR: 1.19; P = 0.009) and nonapical lead position (HR: 2.17; P = 0.042) were all associated with death/transplantation.

CONCLUSIONS

PPM_v in patients with SV is associated with increased risk of heart transplantation and death, despite controlling for increased associated morbidity of the PPM_v cohort. Increased Vp, higher QRS z-score, and nonapical ventricular lead position are all associated with higher risk of adverse outcome and may be modifiable risk factors.

QRS fragmentation and prolongation as predictors of exercise capacity in patients after Fontan palliation

INTRODUCTION

Patients with Fontan anatomy are at increased risk for exercise intolerance and early morbidity and mortality. QRS complex fragmentation (fQRS) and prolongation have been studied in multiple heart diseases, but their clinical importance is unknown in the Fontan population.

METHODS

A retrospective cross-sectional study was performed. ECGs were evaluated for QRS prolongation (>98 %ile for age) and fQRS [ ≥3 R-waves/ notches in the R/S complex (more than 2 in RBBB) in ≥2 contiguous leads]. The primary outcome measures was CPET performance.

RESULTS

Ninety patients (median age 18 years, 57% male, 59% RV dominant) were included; 13% had fQRS and 31% had prolonged QRS. Demographically, patients with fQRS or prolonged QRS were like those without. Peak VO2 (64% vs 63%, p 0.45), VE/VCO2 slope (85% vs 88%, p = 0.74), and O2 pulse (149% vs 129%, p = 0.83) were similar in the fQRS group versus those without. Upon multi-variable regression, body mass index (β = -0.38, p < 0.01) and QRS duration (β = -0.29, p < 0.01) were independently associated with % predicted VO2; fQRS was not. Lower cardiac index (2.2 vs 2.8 L/min/m2, p = 0.03) and higher ventricular end-diastolic pressure (13 vs 10 mmHg, p = 0.02) was seen with fQRS.

CONCLUSIONS

QRS fragmentation is present in patients with Fontan physiology. fQRS showed no association with CPET performance but was related to invasive hemodynamic markers of ventricular performance. QRS duration may be a better predictor of exercise function following Fontan. This article is protected by copyright. All rights reserved.

Effect of Stiffened and Dilated Ascending Aorta on Aerobic Exercise Capacity in Repaired Patients With Complex Congenital Heart Disease

Several studies have reported aortic dilation and increased stiffness of the ascending aorta in patients after repair of congenital heart disease (CHD), which may be a predominant cardiovascular risk. However, the clinical significance has not been described in detail. In this retrospective study, 175 repaired patients with complex CHD achieving biventricular circulation and age-matched 39 control subjects were reviewed (median age: 14.9 and 15.7 years, respectively). We measured the diameters of the ascending aorta and descending aorta from catheterization angiograms to yield Z-scores and stiffness indexes (β) using diameter fluctuations corresponding to pulsatile pressures. Clinical profile, peak oxygen uptake during the cardiopulmonary exercise test, and incidence of unscheduled hospitalization during follow-up was also reviewed. Compared with controls, patients with complex CHD, except for those with aortic coarctation, exhibited significant dilation and increased stiffness of the aortic root and ascending aorta, but not of the descending aorta. In this CHD population (n = 147, including 112 conotruncal anomalies), exercise capacities correlated independently with the diameter Z-score and stiffness index of the ascending aorta along with the history of repetitive thoracotomies, reduced forced vital capacity, and right ventricular hypertension. During a follow-up period (median 15.6 years), either dilation (Z-score >3.5) or increased stiffness (β >6.0) of the ascending aorta stratified morbidity, but no synergistic impact was detected. In conclusion, in repaired patients with complex CHD, a stiffened and dilated ascending aorta was frequently found, exerting significant adverse impacts on diminished exercise capacity and morbidity.

Impact of delayed ventricular wall area ratio on pathophysiology of mechanical dyssynchrony: implication from single-ventricle physiology and 0D modeling

Electrical disparity can induce inefficient cardiac performance, representing an uncoordinated wall motion at an earlier activated ventricular wall: an early shortening followed by a systolic rebound stretch. Although regional contractility and distensibility modulate this pathological motion, the effect of a morphological factor has not been emphasized. Our strain analysis in 62 patients with single ventricle revealed that those with an activation delay in 60-70% of ventricular wall area suffered from cardiac dysfunction and mechanical discoordination along with prolonged QRS duration. A computational simulation with a two-compartment ventricular model also suggested that the ventricle with an activation delay in 70% of the total volume was most vulnerable to a large activation delay, accompanied by an uncoordinated motion at an earlier activated wall. Taken together, the ratio of the delayed ventricular wall has a significant impact on the pathophysiology due to an activation delay, potentially highlighting an indicator of cardiac dysfunction.

Septal Flash-like Motion of the Earlier Activated Ventricular Wall Represents the Pathophysiology of Mechanical Dyssynchrony in Single-Ventricle Anatomy

BACKGROUND

In biventricular physiology, abnormal septal motion is a hallmark of mechanical dyssynchrony in the left bundle branch block. However, in single-ventricle (SV) physiology, morphologic variations in systemic ventricles pose a challenge in evaluating the negative impact of mechanical dyssynchrony. The present study aimed to characterize the pathologic dyssynchronous contraction patterns in patients with SV.

METHODS

In this retrospective study, 70 consecutive postoperative patients with SV anatomy with prolonged QRS duration (25 female patients; median age, 14 years) were enrolled. We divided each SV into two regions and analyzed independent strains using two-dimensional speckle-tracking echocardiography. From an earlier activated ventricular wall, we calculated the strain ratio (R_strains) of two values (%) during the QRS period and the ejection period: (100 + Strain_ejection)/(100 + Strain_QRS). We reviewed the clinical profiles, B-type natriuretic peptide plasma levels, exercise capacity, and morbidity. Six patients who underwent cardiac resynchronization therapy (CRT) were analyzed regarding changes in strain patterns and ventricular volume.

RESULTS

Higher R_strains, indicating a preceding contraction and subsequent dyskinetic dilation of the earlier activated ventricular wall, was associated with increased B-type natriuretic peptide, reduced exercise capacity, and poor outcome. However, delayed contraction of the later activated ventricular wall was not associated with the effects. Decreases in R_strains and ventricular volume reductions were observed in all patients after CRT.

CONCLUSIONS

A specific strain pattern in an earlier activated ventricular wall indicates mechanical dyssynchrony in patients with SV. This pattern is very similar to the septal flash in adult patients with left bundle branch block. This strategy might be a promising approach for selecting appropriate candidates for CRT in patients with SV.

The Progress and Significance of QRS Duration by Electrocardiography in Hypoplastic Left Heart Syndrome

Patients with hypoplastic left heart syndrome (HLHS) are now surviving through to Fontan palliation and beyond, however, with increased morbidity and mortality. Prolonged QRSd has become one of the predictors of morbidity and mortality in certain congenital heart diseases. There is limited data characterizing the QRSd in patients with HLHS. We aimed to describe the changes in QRSd at various times during the lifetime and to evaluate whether QRSd correlates with a higher risk of developing a composite endpoint of heart failure, heart transplant, or death. We conducted a retrospective chart review of patients with HLHS who survived Fontan palliation. QRSd was measured on ECGs at various stages pre- and postsurgical palliations and subsequently at 5 year intervals. Patients with a composite endpoint were compared to those without. A total of 89 patients were included in the final analysis. The QRSd increased significantly with time from 68.7 ± 9.0 ms prior to Norwood to 91.0 ± 14.0 ms immediately following Fontan and 104.7 ± 13.6 ms 15 years after Fontan (p < 0.001). The composite endpoint was observed in 28 patients (31.4%). The time trends of QRSd differ so that the patients having the composite endpoint experienced a greater increase in QRSd over time (p = 0.009). Ever having a QRSd of 120 ms or more predicted the composite endpoint with 93% specificity. The area under the curve of the receiver operator curve analysis was 0.596. A Cox regression analysis demonstrated that QRS duration > 120 ms was independently related to a greater frequency of composite endpoint and this was confirmed by a Kaplan-Meier analysis (p = 0.011). This study unveils a novel relationship between QRSd of 120 ms or more with the composite endpoint. Despite the low sensitivity, this finding on a routine surveillance ECG could help identify HLHS Fontan patients at risk for heart failure, heart transplant, or death.

Pacemakers are associated with a higher risk of late death and transplantation in the Fontan population

BACKGROUND

The need for permanent pacing has been identified as a predictor of poor outcomes in the late survivors of Fontan surgery. However, it is not clear if the need for a pacemaker is a surrogate marker of a declining Fontan state, or if pacing is deleterious to the Fontan circulation.

OBJECTIVES

We sought to compare the long-term outcomes of propensity-matched Fontan patients with and without a permanent pacemaker.

METHODS

Patients who have survived Fontan completion with a documented history of cardiac arrhythmia were identified from the Australia and New Zealand Fontan Registry. Pacemaker insertion details, cardiac function and electrophysiological data were obtained for the patients with a permanent pacemaker. Survival analysis was performed with propensity score matching to compare late survival and outcomes in patients with versus without a pacemaker.

RESULTS

There was a total of 310 patients with a history of cardiac arrhythmia, of which 126 (41%) had a permanent pacemaker. After propensity-score matching, 99 pairs were generated (n = 198). Patients with a permanent pacemaker had a higher risk of death (HR 3.32 95% CI 1.60-6.90, p = 0.001) and death or transplantation (HR 3.55 95% CI 1.87-6.73, p < 0.001). Patients who were only paced atrially were not at a significantly increased risk of death or transplantation. However, patients who were ventricular paced >50% of the time were much more likely to encounter late death or transplantation (HR 3.82 95% CI 1.64-8.95, p = 0.002).

CONCLUSIONS

Having a permanent pacemaker and needing ventricular pacing is likely associated with an increased risk of death and transplantation in patients with a Fontan circulation.

Clinical-Physiological Considerations in Patients Undergoing Staged Palliation for a Functionally Single Ventricle

OBJECTIVES

The objectives of this review are to discuss the pathophysiology of the circulation with a functionally univentricular heart, with a focus on the unique physiologic characteristics, which provide the underpinnings for the management of these complex patients.

DATA SOURCE

MEDLINE and PubMed.

CONCLUSIONS

The circulation of the patient with a functionally univentricular heart displays unique physiologic characteristics, which are quite different from those of the normal biventricular circulation. There are profound differences within the heart itself in terms of ventricular function, interventricular interactions, and myocardial architecture, which are likely to have significant implications for the efficiency of ventricular ejection and metabolism. The coupling between the systemic ventricle and the aorta also displays unique features. The 3D orientation of the Fontan anastomosis itself can profoundly impact cardiac output, although the "portal" pulmonary arterial bed is a crucial determinant of overall cardiovascular function. As a result, disease-specific approaches to improve cardiovascular function are required at all stages during the care of these complex patients.

Adult patients with Fontan circulation: What we know and how to manage adults with Fontan circulation?

Most of patients after the Fontan operation can reach their adulthood, however, the management strategy for this complex pathophysiology has not been yet established. In general, elevated central venous pressure (CVP) and low cardiac output (CO) due to impaired ventricular preload characterize the Fontan circulation and the ideal hemodynamics could be a combination of a lower CVP with a higher CO. Thus, preserved functional systemic ventricle with low pulmonary artery resistance is thought to be crucial for better long-term outcome. However, on the other hand, because of the unique hemodynamics, these patients have significantly higher incidence of complications, sequelae, and even mortality. The major complications are supraventricular arrhythmias, heart failure, and Fontan-related problems, including protein-losing enteropathy and pulmonary arteriovenous fistulae, both of which are refractory to the treatments, and most of these "Fontan inconveniences" increase as patients age. In addition, one of the recent emerging problems is Fontan-associated liver disease that includes liver cirrhosis and hepatocellular carcinoma. Furthermore, women with Fontan circulation also reach childbearing age and there have been increasing numbers of reports showing a high incidence of pregnancy-associated complications. All these problems may be a part of "Fontan inconveniences" because most of the current Fontan patients are still "young" i.e. in their twenties or thirties and it may be not surprising that more new Fontan-associated pathophysiology emerges as patients age. Recent evidence reminds us of the concept that adult Fontan pathophysiology is not just a cardiovascular disease, rather, a multiorgan disease with many interactions between cardiovascular and non-cardiovascular organs. Therefore, a multidisciplinary approach is mandatory to take care of and anticipate the better long-term outcome.

QRS Duration Changes in Patients with Single Ventricle Physiology: Birth to 10 Years

BACKGROUND

QRS prolongation may be a predictor of mortality in certain forms of congenital heart disease. Minimal data exist describing changes in QRS duration in patients with single ventricles (SVs). The goal was to describe changes in QRS duration in patients with SV and to determine if differences existed between single right ventricle (sRV) versus single left ventricle (sLV) patients.

METHODS

Chart review was performed on patients with SV physiology. Patients were divided into sRV and sLV groups. QRS durations were measured monthly for the first 6 months, at 1 year, and then yearly until 10 years. t-tests were used for analysis.

RESULTS

One hundred sixty patients were evaluated (95 sRV, 65 sLV). The greatest change in QRS duration for the entire cohort occurred in the first 6 months of life versus 6 months to 10 years of age (1.81 ms/month vs 0.20 ms/month). sRV QRS durations were significantly longer than sLV QRS durations at 1 year (78.9 ± 12.6 ms vs 73.2 ± 11.9 ms), 2 year (81.7 ± 14.7 ms vs 73.4 ± 12.5 ms), 4 year (84.2 ± 12.1 ms vs 77.9 ± 16.4 ms), 6 year (90.8 ± 12.7 ms vs 83.4 ± 13.4 ms), 7 year (90.8 ± 16.5 ms vs 81.2 ± 16.6 ms), and 8 year (96.7 ± 13.6 ms vs 84.8 ± 13.9 ms) time points.

CONCLUSION

The greatest change in QRS duration in SV patients occurred in the first 6 months of life when these patients' ventricles were volume loaded. Differences in QRS duration between sRV and sLV patients occurred early in life. Further studies are needed to determine if minimizing volume load early in life decreases the rate of change in QRS duration.

Haemodynamic characteristics before and after the onset of protein losing enteropathy in patients after the Fontan operation

OBJECTIVES

Determinant risk factors for developing protein losing enteropathy (PLE), including haemodynamics, remain unclear in patients after the Fontan operation.

METHODS

Our purpose was to characterize the serial PLE haemodynamics before and after the onset and to determine the risk factors based on the cardiac catheterization-based analysis.

RESULTS

Of 354 Fontan survivors who had undergone postoperative cardiac catheterizations, we experienced 26 PLE patients during the follow-up. Non-left ventricular morphology systemic ventricle, functional one-lung pulmonary circulation and an early postoperative high central venous pressure (CVP) were associated with the PLE onset and the high CVP (odds ratio (OR) = 1.19 per 1 mmHg, 95% confidence interval (CI) 1.04-1.37, especially ≥12 mmHg, OR = 3.09, 95% CI 1.25-7.64, P < 0.05 for both) and one-lung pulmonary circulation (OR = 10.0-10.5, P < 0.001) independently predicted the onset. At the time of the PLE onset, a Fontan route stenosis/obstruction, arrhythmias, ventricular dysfunction/heart failure and pulmonary arterio-venous fistulae were demonstrated in 10 (38%), 8 (31%), 4 (15%) and 3 (12%) patients, respectively. When compared with 56 excellent Fontan survivors, the high CVP, ventricular end-diastolic pressure, and pulmonary artery resistance, and the low arterial oxygen saturation, systemic artery pressure, and ventricular ejection fraction characterized the pre-PLE Fontan haemodynamics (P < 0.05-0.0001). However, the following intensive treatments reduced the CVP, systemic artery pressure and cardiac output (P < 0.05-0.01), resulting in haemodynamics no different from those of the excellent survivors, except for the low systemic pressure (P < 0.0001).

CONCLUSIONS

The pre-PLE haemodynamics was characterized by several impaired haemodynamics, while those after PLE only by a low systemic pressure. A high early postoperative CVP was the only haemodynamic predictor for a new onset of PLE. Strict selective criteria for the operation and strategies to eliminate CVP-raising factors are mandatory to prevent a new onset of PLE.

QRS duration changes in patients with hypoplastic left heart syndrome undergoing hybrid palliation: prehybrid to post-Fontan

BACKGROUND

QRS prolongation has been shown to be a predictor of mortality in patients with certain forms of congenital heart disease. QRS changes have not been well described in patients with single ventricle physiology, particularly in those undergoing the hybrid procedure.

OBJECTIVE

To describe QRS changes in a cohort of patients with hypoplastic left heart syndrome (HLHS) who underwent hybrid palliation and to evaluate if QRS duration is associated with mortality.

METHODS

Chart review of 54 patients with HLHS who underwent hybrid procedure between 2002 and 2009 was performed. Patients awaiting surgical palliation were excluded. Patients who survived Fontan completion (HLHS-S, n = 30) were compared to non-survivor (HLHS-NS, n = 24). Electrocardiograms were reviewed for maximal QRS duration (ms) at three pre- and postsurgical stages: (1) hybrid procedure, (2) comprehensive stage 2 procedure, and (3) Fontan procedure.

RESULTS

In HLHS-S, there was a significant increase in QRS from birth to Fontan completion (15.6 ± 9.3 ms). QRS duration increased 8.5 ± 8.9 ms between posthybrid to precomprehensive stage 2, and 5.4 ± 9.7 ms between postcomprehensive stage 2 to Fontan. Following Fontan procedure, mean QRS decreased 4.3 ± 8.5 ms. There was no significant mean difference in QRS change between HLHS-S and HLHS-NS following hybrid procedure. Pre- and posthybrid and pre- and postcomprehensive stage 2 QRS durations were not different between HLHS-S and HLHS-NS who underwent a comprehensive stage 2 procedure. There was a significant difference in QRS difference following comprehensive stage 2 in HLHS-S (0.9 ± 7.1 ms) compared to HLHS-NS (-7.1 ± 10.0 ms).

CONCLUSIONS

QRS duration significantly increased from hybrid to Fontan completion in HLHS-S. There was a significant decrease in QRS duration in patients who died following comprehensive stage 2 procedure. Larger studies are needed to assess the significance of these QRS changes.

Long-term serial aerobic exercise capacity and hemodynamic properties in clinically and hemodynamically good, "excellent", Fontan survivors

BACKGROUND

The serial hemodynamics and predictors of long-term, good Fontan survivors remain unknown.

METHODS AND RESULTS

Two hundred one patients who had undergone a Fontan operation before September 1998 were reviewed to compare their long-term clinical status with serial hemodynamics. During a mean follow-up of 18.7 years, 47 (30.1%) of the 156 survivors had no clinical events that required an unscheduled hospitalization. Of those, 18 survivors exhibited good serial hemodynamics and the respective mean values of central venous pressure (CVP, mmHg), cardiac index (CI, L·min(-1)·m(2)), and ventricular ejection fraction (EF, %) before and 1, 5, 10, and 15 years after the operation were as follows: 3.8, 9.0, 11.3, 10.6, and 10.1 (CVP); 3.6, 3.1, 2.8, 2.6, and 2.6, and 69 (CI); 57, 56, 58, 54, and 53 (EF). Serial values of CVP, ventricular end-diastolic pressure (EDP) and the grade of atrioventricular valve regurgitation (AVVR) were lower and the peak oxygen uptake was greater in the good patients (P<0.05 for all). A 1-year postoperative lower CVP and no history of AVVR repair during the Fontan operation independently predicted the good patients (P<0.05).

CONCLUSIONS

A lower CVP and EDP, better atrioventricular valvular function, and greater exercise capacity characterize good Fontan survivors and an early postoperative low CVP without an AVVR repair predicts good survivors.

Effect of ventricular volume before unloading in a systemic ventricle supporting the Fontan circulation

The influence of volume overload on ventricular performance has been previously investigated but primarily with respect to the duration of overload. The aim of the present study was to elucidate whether the magnitude of the preoperative volume overload, represented by the ventricular volume, has any effect on ventricular performance long after the Fontan operation in patients with tricuspid atresia. We evaluated consecutive changes in hemodynamic catheterization data obtained at 1, 5, and 10 years after primary Fontan repair. The variables were compared between patients with larger (n = 20) and smaller (n = 21) ventricles (preoperative end-diastolic volume [percentage of predicted] 262 ± 33%, maximum 320% vs 182 ± 22%, minimum 133%, respectively). In a subgroup of patients (n = 33) who underwent symptom-limited exercise at 10.7 ± 3.0 postoperative years, the peak oxygen uptake was measured, and the potential predictors were interrogated. The difference in ventricular contractility between the groups tended to increase with time, with those with a larger ventricle showing poorer contraction, irrespective of whether it was assessed in a load-dependent (ejection fraction) or load-independent (end-systolic elastance) manner. The differences in these variables reached statistical significance at 10 years (p = 0.028 and p = 0.032). Multivariate analysis indicated a larger ventricle was an independent risk factor of poorer aerobic capacity (p = 0.047). In conclusion, ventricular performance was less preserved in those with a larger ventricle, which might result in suboptimal aerobic capacity. Our findings suggest not only early unloading, but also avoidance of excessive volume overload is of importance to minimize the deleterious effect of volume overload on an inherently susceptible ventricle.