Aortic reservoir function after arterial switch operation in elementary school-aged children

Increased aortic pressures and pulsatile afterload components promote concentric left ventricular remodeling in adults with transposition of the great arteries and arterial switch operation

BACKGROUND

Functional abnormalities of the ascending aorta (AA) have been mainly reported in young patients who underwent arterial switch operation (ASO) for transposition of the great arteries (TGA).

OBJECTIVES

To compare systolic, diastolic brachial and central blood pressures (bSBP, bDBP, cSBP, cDBP), aortic biomechanical parameters, and left ventricular (LV) afterload criteria in adult ASO patients with healthy controls and to assess their relationships with LV remodeling and aortic size.

MATERIALS AND METHODS

Forty-one prospectively enrolled patients (16.8 to 35.8 years) and 41 age- and sex-matched healthy volunteers underwent cardiac MRI to assess LV remodeling with simultaneous brachial BP estimation. After MRI, carotid-femoral tonometry was performed to measure pulse wave velocity (cfPWV), cSBP and cDBP for further calculation of pulse pressure (cPP), AA distensibility (AAD), and AA and LV elastance (AAE, LVE).

RESULTS

bSBP, bDBP, cSBP,cDBP and cPP were all significantly higher in ASO group than in controls: cSBP (116.5 ± 13.8 vs 106.1 ± 12.0, p < 0.001), cDBP (72.5 ± 6.9 vs 67.1 ± 9.4, p = 0.002), cPP (44.0 ± 12.1 vs 39.1 ± 8.9, p = 0.003) and not related to aortic size. AAD were decreased in ASO patients vs controls (4.70 ± 2.72 vs 6.69 ± 2.16, p < 0.001). LV mass was correlated with bSBP, cSBP, cPP (ρ = 0.48; p < 0.001), while concentric LV remodeling was correlated with AAE (ρ = 0.60, p < 0.001) and LVE (ρ = 0.32, p = 0.04), but not with distensibility.

CONCLUSION

Even without reaching arterial hypertension, aortic sBP and PP are increased in the adult TGA population after ASO, altering the pulsatile components of afterload and contributing to LV concentric remodeling.

Vascular aging in adult congenital heart disease-a narrative review

Background and Objective

Many studies about the high prevalence of cardiovascular disease in adults with congenital heart disease (CHD) have been published in response to the growing number of adult patients with CHD. The aging process leads to hypertension and cardiovascular disease, which is caused by a degenerative change in the systemic arterial system characterized by the stiffening of elastic arteries (known as arteriosclerosis) and the enlargement of aorta. In patients with CHD, aortic dilatation (so-called aortopathy) is one of the most frequent complications. It is well known the anatomical and histological changes in aortopathy are similar to those in aging process. The increase of pulse wave velocity (PWV) enhances pressure wave reflection, and it augments left ventricular afterload and impairs the coronary supply-workload balance in aging. This article reviews the aortic function in patients with CHD, aiming to provide a new direction for the management of their cardiovascular aging process.

Methods

Papers on vascular physiology in CHD were retrieved. I searched all original papers and reviews about the vascular physiology in CHD using PubMed, published from January 1, 1973 to June 30, 2022, in English.

Key Content and Findings

Enhancement of pressure wave reflection has been reported in many CHDs. Although PWV in whole aorta is not necessarily elevated, the abnormal arterial stiffness gradient is common in patients with CHD.

Conclusions

Many reports concerning functional abnormalities of the aorta have been reported. The abnormalities can result in cardiovascular disease and organ damage. The practitioners should carefully treat patients with CHD while paying attention to their aging process.

Anatomical reconstruction of proximal coronary artery stenosis in children

OBJECTIVES

Timing and method of surgical reconstruction for non-sclerotic proximal coronary artery stenosis, occuring de-novo or post coronary artery transfer, are evolving. We have pursued a technique of anatomical reconstruction of ostial and short segment proximal coronary artery stenosis and atresia in children, using patch plasty or interposition vein graft. Herein, we discuss the medium- to long-term outcome.

METHODS

Nine consecutive children undergoing ten left main coronary artery reconstructions using autologous great saphenous vein patch (n = 4), autologous pericardium (n = 4), xenopericardium (n = 1) or great saphenous vein interposition graft (n = 1) were retrospectively analysed. Complementary wedge resection of the stenotic coronary ostium was performed in chronic cases.

RESULTS

The aetiology of coronary artery stenosis was post arterial switch operation (n = 6), Takayasu`s arteritis (n = 1), idiopathic left main coronary artery atresia (n = 1) and anomalous origin of the left coronary artery from the pulmonary artery (n = 1). Median age and weight at operation were 0.15 (range 0.01-13.1) years and 4.4 (range 3 -13.1) kilograms, respectively. Survival was 100% at median follow-up of 12.6 (range 1-19.2) years. All patients showed normal left ventricular ejection fraction on transthoracic echocardiogram. In one patient, kinking of the proximal left circumflex artery resulted in non-significant obstruction. In all other cases, follow-up catheter angiography revealed unobstructed coronary arteries. Cardiac magnetic resonance tomography showed no significant perfusion deficit in any child.

CONCLUSIONS

Anatomical reconstruction of the proximal left coronary artery using autologous saphenous vein may allow optimal restoration of physiological coronary blood flow, keeping the option of future coronary bypass operation open.

Similar Myocardial Perfusion and Vascular Stiffness in Children and Adolescents with High Lipoprotein (a) Levels, in Comparison with Healthy Controls

Background and Aims

This study investigated the possible correlation between elevated lipoprotein (a) (Lp(a)) levels and early vascular aging biomarkers in healthy children and adolescents.

Methods

Twenty-seven healthy children/adolescents, mean age 9.9 ± 3.7 years, with high Lp(a) levels without other lipid abnormalities and 27 age- and sex-matched controls with normal Lp(a) levels, were included in the study. The investigation of possible early vascular aging was assessed by measuring vascular function indices: carotid intima-media thickness (c-IMT), pulse wave velocity (PWV), augmentation index (AIx), and subendocardial viability ratio (SEVR).

Results

Although serum lipid values were within normal levels, mean values of total cholesterol and apolipoprotein B were higher in the group of children with high Lp(a) levels than controls (p = 0.006 and p < 0.001, respectively). Vascular function indices did not show significant differences, neither between the 2 groups nor in the subgroups of children with increased Lp(a) levels. These subgroups were defined by the presence or absence of family history of premature coronary artery disease. Lp(a) levels did not show a significant correlation with the other parameters studied, both regarding the whole sample (patients and controls), as well as in the subgroups of elevated Lp(a) levels. However, in the group of children with high Lp(a) levels, c-IMT and PWV were positively correlated with diastolic blood pressure (r = 0.427, p = 0.026 and r = 0.425, p = 0.030, respectively), while SEVR was negatively correlated with AIx (r = -0.455, p = 0.017).

Conclusions

Healthy children and adolescents with high Lp(a) levels do not yet have impaired vascular indices, compared to controls. However, in order to prevent early atherosclerosis, it is crucial to early identify and follow up children with high Lp(a) levels and positive family history of premature coronary disease or other cardiovascular risk factors.

Implication of Aortic Root Dilation and Stiffening in Patients with Tetralogy of Fallot

Progressive aortic root dilation and stiffening have been reported in patients with tetralogy of Fallot (TOF), even after repair. However, the implications of such aortic dilation and stiffening have not been fully assessed. A stiff aorta has a negative effect on the coronary circulation. 15 patients with TOF after repair were enrolled in this study. Using a left ventriculogram and pressure waveform recorded by a pressure sensor-mounted catheter, we analyzed the diameter and distensibility of the ascending and descending aorta. We also calculated the subendocardial viability ratio (SEVR), which measures the cardiac blood supply-workload balance. These values were compared with those in one-to-one age-matched controls. Moreover, the correlation between the diameter ratio (aortic diameter of the patient/aortic diameter of the matched control subject) and the distensibility ratio (distensibility of the patient/distensibility of the matched control subject) was analyzed. The mean age of patients was 3.9 ± 1.6 years. In patients with TOF, the indexed diameter was larger (0.20 ± 0.02 vs. 0.15 ± 0.02 mm/cm, p < 0.0001) and the distensibility was lower (5.1 ± 2.2 vs. 7.7 ± 2.0 cm² dynes^-1 10^-6, p = 0.0009) in the ascending aorta than in control subjects. There was no difference in the SEVR between patients and control subjects. The distensibility ratio was significantly negatively correlated with the indexed diameter ratio in the ascending aorta (r² = 0.35, p = 0.019). Regardless of the aortic stiffening, the cardiac blood supply-workload balance was maintained. We speculate that the aortic root dilation might be a mechanism to functionally complement aortic stiffness in patients with TOF.

Central diastolic pressure decay mediates the relationship between aortic stiffness and myocardial viability: potential implications for aortosclerosis-induced myocardial ischemia

OBJECTIVE

Stiffening of the aorta often precedes coronary events, but little is known about the aetiological mechanism. We hypothesized that the predisposition to myocardial ischemia could be attributable to aortosclerosis-induced alterations in the central haemodynamics during diastole.

METHODS

Using noninvasive tonometry and ultrasonography, we investigated the arterial pressure pulse waveforms, pulse wave velocities (PWVs) and compliance in 222 patients with hypertension. The diastolic pressure decay was quantified by fitting a mono-exponential curve as P(t) =  P0e [λ: decay index; P0: end-systolic pressure; t: time from end-systole]. The myocardial oxygen supply/demand balance was estimated from the subendocardial viability index (SVI).

RESULTS

The aortic pressure decay fit to an exponential curve significantly (R = 0.98 ± 0.02) and more closely than the radial pressure decay (P < 0.001). The aortic decay index (median, 0.59 s) was associated with the aortic PWV and compliance (but not with the peripheral PWV or resistance), even after controlling for age, sex, renal function, diabetes and hypercholesterolemia (P < 0.001). Also, both the aortic PWV and compliance (together with the augmentation index) were related to the SVI, although these relationships were no longer significant after accounting for the decay index. Mediation analysis revealed substantial mediating effects of the decay index on the relationship between aortic PWV or compliance and SVI (75-100%), despite the lack of similar effects of the augmentation index.

CONCLUSION

Aortic stiffening with reduced compliance potentially impairs myocardial viability by accelerating the diastolic exponential decay (rather than through enhancing late-systolic augmentation) of the central blood pressure, thus predisposing hypertensive patients to ischemic heart disease.

Preserved Cardiac Blood Supply-Workload Balance in Pediatric Patients After Aortic Arch Repair

One of the most important problems in patients with aortic coarctation after aortic arch repair is future cardiovascular disease. We have previously reported that the enhancement of aortic pressure wave reflection in patients could be one of the causes of future cardiovascular diseases, because it results in an increase of the left ventricular workload and is disadvantageous for coronary circulation. Seventeen patients who had undergone aortic arch repair without pressure gradient in their aortic arch were enrolled. An ascending aortic pressure waveform was recorded by a pressure-sensor-mounted catheter, and a subendocardial viability ratio, which measures cardiac blood supply-workload balance, was calculated. The values were compared with those in age-matched controls. The patients' mean age was 6.8 ± 2.8 years. The mean ascending aortic systolic pressure was higher (100.4 ± 12.9 vs. 90.2 ± 8.9 mmHg, p = 0.0011) and the pulse pressure was wider (38.1 ± 7.1 vs. 32.5 ± 5.4 mmHg, p = 0.0072) in patients than in control subjects. There was no difference in the mean subendocardial viability ratio (1.01 ± 0.25 vs. 1.01 ± 0.24, ns), while the mean tension time index (27.4 ± 5.6 vs. 23.0 ± 3.3, p = 0.0001) and diastolic pressure time index (28.4 ± 11.1 vs. 23.6 ± 8.0, p = 0.0082) were higher in patients than in controls. The cardiac blood supply-workload balance was preserved in patients after aortic arch repair, despite an increase in their cardiac workload.

Ventricular-vascular dynamics in pediatric patients with heart failure and preserved ejection fraction

OBJECTIVE

The details of the ventricular-vascular dynamics of heart failure with preserved ejection fraction (HFpEF) in children remain poorly understood. We tested the hypothesis that pediatric HFpEF patients have ventricular systolic, diastolic, and arterial stiffening at rest as well as impaired reserve function associated with coronary supply/demand imbalance.

METHODS

We studied the ventricular pressure-area relationship in 22 pediatric HFpEF patients and 22 control subjects before and after dobutamine infusion and during abdominal compression. Coronary supply/demand balance was assessed by subendocardial viability ratio (SEVR) calculated from the aortic pressure waveform.

RESULTS

Compared with controls, the HFpEF patients had significantly higher end-systolic (Ees) and arterial (Ea) elastance. Increased ventricular diastolic stiffness also occurred in the HFpEF patients, resulting in modest elevation of end-diastolic pressure (EDP) at rest (13.6±4.3 vs. 7.3±2.3mmHg, P<0.0001). The difference in EDP became more evident with a preload increase through abdominal compression, indicating a limited diastolic reserve in HFpEF patients (EDP changes; 11.3±6.2 for HFpEF vs. 3.4±0.6mmHg for controls, P=0.016). The HFpEF patients exhibited impaired beta-adrenergic reserve in ventricular contractility and ventricular-arterial coupling in response to dobutamine infusion. SEVR was significantly lower in the HFpEF (0.64±0.11) than in the control (0.79±0.07, P<0.0001) and was significantly correlated with LV diastolic stiffness and dobutamine-induced changes in ventricular contractility.

CONCLUSIONS

HFpEF in children involves higher ventricular-arterial stiffness at rest as well as impaired systolic and diastolic reserve, which closely correlate with impaired coronary supply/demand balance.

Ventricular sympathetic innervation in patients with transposition of the great arteries after arterial switch operation and Rastelli procedure: impact of arterial dissection and coronary reimplantation

BACKGROUND

Coronary flow reserve (CFR) is reduced in patients with transposition of the great arteries (TGA) after the arterial switch operation (ASO). Dissection of the great arteries and coronary reimplantation may result in sympathetic denervation, with a negative effect on myocardial perfusion.

METHODS AND RESULTS

18 patients with TGA participated in the study; 9 had ASO (20.8±5.8 years). Controls were 9 patients after Rastelli procedure (22.1±6.8 years). Sympathetic innervation was measured by positron emission tomography using(11)C epinephrine (EPI). Left ventricular EPI-retention ranged from 6.1% to 15.9%/min. Patients undergoing more than 1 operation had significantly reduced EPI-retention (P<0.001). EPI-retention and time interval after surgery correlated significantly (r=0.81, P<0.001) and was higher in patients undergoing surgery at an earlier age (P<0.001). No significant difference could be found between patients after ASO or Rastelli repair. Aortic cross-clamp time inversely correlated with EPI-retention (r=-0.72; P<0.001).

CONCLUSIONS

The ASO procedure had a negative effect on sympathetic innervation of the myocardium, but because of reinnervation myocardial perfusion is not essentially altered by this mechanism. Heart surgery and prolonged aortic cross-clamp time have a negative effect on the norepinephrine content of cardiac sympathetic nerve terminals. Parameters such as ventricular performance and cardiopulmonary exercise capacity were unaffected by the degree of EPI-retention.