Arterial hemodynamic indexes in Marfan's syndrome

Nitric oxide in the Marfan vasculature: Friend or foe?

Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the FBN1 gene, which encodes fibrillin-1, a protein essential for the formation and stabilization of elastic fibers as well as signaling homeostasis. Progressive aortic root widening is the most serious manifestation of MFS as it can lead to aortic dissection, aneurysm formation and rupture. However, despite their ability to decrease the hemodynamic stress the aorta is subjected to, anti-hypertensive medications often lead to underwhelming reductions in the rate of aortic root dilation, which illustrates how fragmental our understanding of MFS-associated aortic remodeling is. This manuscript summarizes recent evidence that document nitric oxide (NO) synthase (NOS)-related changes to the vasculature during the pathogenesis of MFS and how they result in a unique state of vascular dysfunction that likely plays a causal role in the aortic root widening process. We also review how clinic-approved and experimental therapies as well lifestyle approaches may promote aortic root stability by correcting NO homeostasis, which if properly optimized may improve outcomes in this population afflicted by a notoriously refractory type of aortopathy.

Aortic Regurgitation Is Associated With Ascending Aortic Remodeling in the Nondilated Aorta

OBJECTIVE

The probability of aortic complications in patients with bicuspid aortic valve is higher in association with aortic regurgitation (AR) compared with aortic stenosis (AS) or normally functioning valves. The objective of this study was to determine whether this is related to the specific characteristics of aneurysmatic dilatation that includes AR or whether AR itself has a negative impact on the aortic wall, independent of aneurysmatic dilatation. Approach and Results: Nondilated aortic specimens were harvested intraoperatively from individuals with tricuspid aortic valves and either AS (n=10) or AR (n=16). For controls, nondilated aortas were harvested during autopsies from individuals with tricuspid aortic valves and no evidence of aortic valve disease (n=10). Histological and immunohistochemical analyses revealed that compared with control aortas, overall medial degeneration was more severe in AR-aortas (P=0.005) but not AS-aortas (P=0.23). This pathological remodeling included mucoid extracellular matrix accumulation (P=0.005), elastin loss (P=0.003), elastin fragmentation (P=0.008), and decreased expression of fibrillin (P=0.003) and collagen (P=0.008). Furthermore, eNOS (endothelial nitric oxide synthase) expression was decreased in the intima (P=0.0008) and in vasa vasorum (P=0.004) of AR-aortas but not AS-aortas (all P>0.05). Likewise, subendothelial apoptosis was increased in AR-aortas (P=0.03) but not AS-aortas (P=0.50).

CONCLUSIONS

AR has a negative effect on the nondilated ascending aortic wall. Accordingly, our results support the need for more detailed studies of the aortic wall in relation to aortic valve disease and may ultimately lead to more aggressive clinical monitoring and/or surgical criteria for patients with relevant AR. Graphic Abstract: A graphic abstract is available for this article.

Myocardial Function, Heart Failure and Arrhythmia in Marfan Syndrome: A Systematic Literature Review

Marfan syndrome (MFS) is a heritable systemic connective tissue disease with important cardiovascular involvement, including aortic root dilatation and mitral valve prolapse. Life expectancy in patients with MFS is mainly determined by cardiovascular complications, among which aortic dissection or rupture are most dreaded. In recent years, heart failure and ventricular arrhythmia have drawn attention as extra-aortic cardiovascular manifestations and as additional reported causes of death. Imaging studies have provided data supporting a primary myocardial impairment in the absence of valvular disease or cardiovascular surgery, while studies using ambulatory ECG have demonstrated an increased susceptibility to ventricular arrhythmia. In this paper, current literature was reviewed in order to provide insights in characteristics, pathophysiology and evolution of myocardial function, heart failure and ventricular arrhythmia in MFS.

Central artery stiffness and thoracic aortopathy

Thoracic aortopathy, especially aneurysm, dissection, and rupture, is responsible for significant morbidity and mortality. Uncontrolled hypertension and aging are primary risk factors for such conditions, and they contribute to an increase in the mechanical stress on the wall and an increase in its structural vulnerability, respectively. Select genetic mutations also predispose to these lethal conditions, and the collection of known mutations suggests that dysfunctional mechanosensing and mechanoregulation of the extracellular matrix may contribute to pathogenesis and disease progression. In the absence of a well-accepted pharmacotherapy, nonsurgical treatments tend to focus on reducing the mechanical loading on the aorta, particularly via the use of antihypertensive medications and recommendations to avoid strenuous exercises such as weight lifting. In this brief review, we discuss the important effects of central artery stiffening on global hemodynamics and, in particular, on the increase in pulse pressure that acts on the proximal thoracic aorta. We consider Marfan syndrome as an illustrative aortopathy but discuss other conditions leading to thoracic aortic aneurysm and dissection. We highlight the importance of phenotyping the aorta biomechanically, not just clinically, and emphasize the utility of mouse models in elucidating molecular and mechanical mechanisms of disease. Notwithstanding the widely recognized role of central artery stiffening in driving end-organ disease, we suggest that there is similarly a need to consider its key role in thoracic aortopathy.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.

Ambulatory (24 h) blood pressure and arterial stiffness measurement in Marfan syndrome patients: a case control feasibility and pilot study

BACKGROUND

The aim of this work is the investigation of measures of ambulatory brachial and aortic blood pressure and indices of arterial stiffness and aortic wave reflection in Marfan patients.

METHODS

A case-control study was conducted including patients with diagnosed Marfan syndrome following Ghent2 nosology and healthy controls matched for sex, age and daytime brachial systolic blood pressure. For each subject a 24 h ambulatory blood pressure and 24 h pulse wave analysis measurement was performed.

RESULTS

All parameters showed a circadian pattern whereby pressure dipping was more pronounced in Marfan patients. During daytime only Marfan patients with aortic root surgery showed increased pulse wave velocity. In contrast, various nighttime measurements, wave reflection determinants and circadian patterns showed a significant difference.

CONCLUSIONS

The findings of our study provide evidence that ambulatory measurement of arterial stiffness parameters is feasible and that these determinants are significantly different in Marfan syndrome patients compared to controls in particular at nighttime. Further investigation is therefore indicated.

Perturbations of mechanotransduction and aneurysm formation in heritable aortopathies

Thoracic aortic aneurysm and dissection in young and middle aged patients is increasingly recognised as due to genetic aortopathy. Mutations in multiple genes affecting proteins in the extracellular matrix, microfibrillar structure, the endothelium and cell signalling pathways have been associated with thoracic aortic disease. The TGFß signalling pathway appears to play a key role in mediating abnormal aortic growth and aneurysm formation. A challenge remains in understanding how the many different gene mutations can result in deranged TGFß signalling. This review examines the functional relationships between key structural and signalling proteins, with reference to the need for maintenance of homeostasis in mechanotransduction within the aortic wall. A mechanism, through which perturbations in mechanotransduction, arising from different gene mutations, results in altered TGFß signalling is described.

Losartan added to β-blockade therapy for aortic root dilation in Marfan syndrome: a randomized, open-label pilot study

OBJECTIVE

To assess the tolerability and efficacy of the investigational use of the angiotensin II receptor blocker losartan added to β-blockade (BB) to prevent progressive aortic root dilation in patients with Marfan syndrome (MFS).

PATIENTS AND METHODS

Between May 1, 2007, and September 31, 2011, 28 patients with MFS (11 males [39%]; mean ± SD age, 13.1±6.3 years) with recognized aortic root dilation (z score >2.0) and receiving BB (atenolol or propranolol) treatment were enrolled. They were randomized to receive BB (BB: 13 patients) or β-blockade and losartan (BB-L: 15 patients) for 35 months.

RESULTS

In the BB-L group, aortic root dilation was reduced with treatment, and the annual dilation rate of the aortic root was significantly lower than that of the BB group (0.10 mm/yr vs 0.89 mm/yr; P=.02). The absolute aortic diameters at the sinus of Valsalva, annulus, and sinotubular junction showed similar trends, with a reduced rate of dilation in the BB-L group (P=.02, P=.03, and P=.03, respectively). Five patients (33%) treated with BB-L were noted to have a reduced aortic root diameter. However, the differences between the groups regarding changes in aortic stiffness and cross-sectional compliance were not statistically significant.

CONCLUSION

This randomized, open-label, active controlled trial mostly based on a pediatric population demonstrated for the first time that losartan add-on BB therapy is safe and provides more effective protection to slow the progression of aortic root dilation than does BB treatment alone in patients with MFS.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00651235.

Effects of atenolol, perindopril and verapamil on haemodynamic and vascular function in Marfan syndrome - a randomised, double-blind, crossover trial

BACKGROUND

Aortic dilatation is the main therapeutic target in patients with Marfan syndrome. Standard treatment with a β-blocker may not lower central pulse pressure - the major objective - because it does not do so in hypertension, unlike angiotensin-converting enzyme inhibitors and calcium-channel blockers. We therefore performed a prospective, randomised, double-blind, crossover trial to compare the effects of these three agents on large artery function and central aortic pressure in patients with Marfan syndrome.

METHODS AND RESULTS

Eighteen patients had applanation tonometry, pulse wave analysis and echocardiography, before and after atenolol 75 mg, perindopril 4 mg and verapamil 240 mg, each given for 4 weeks, in a random order, with 2 weeks between medications. Fourteen patients completed the study. Within-drug comparisons demonstrated that perindopril (-10·3 mmHg, P = 0·002), verapamil (-9·2 mmHg, P = 0·003) and atenolol (-7·1 mmHg, P = 0·01) all reduced central systolic pressure and brachial pressure; central changes were least, and peripheral changes greatest with atenolol but between-drug comparisons (analysis of covariance) were not significant. There was a trend for augmentation to be reduced by perindopril (-6·3%, P = 0·05), verapamil (-5·5%, P = 0·07) and atenolol (-3·2%, P = 0·09). Only atenolol reduced heart rate (by 16%) and delayed expansion in the arch and abdominal aorta (by 8% and 11%) (P < 0·001, P < 0·01 and P < 0·05, respectively, for between-drug comparisons).

CONCLUSIONS

Perindopril, verapamil and atenolol all reduced peripheral and central systolic pressure. As atenolol slowed heart rate and delayed aortic wave travel, β-blockade may have a continuing role in the treatment of patients with Marfan syndrome.

Current and future pharmacological treatment strategies with regard to aortic disease in Marfan syndrome

INTRODUCTION

Marfan syndrome is a multisystemic connective tissue disorder caused mainly by mutations in the fibrillin-1 gene. The entire cardiovascular system is affected in patients with Marfan syndrome. Aortic root dilatation, aortic valve regurgitation or - the most feared and life-threatening symptom - aortic root dissection are the most common manifestations. Therapeutic strategies, such as prophylactic aortic root surgery and pharmacological therapy, focus on the prevention of aortic dissection. Currently, the standard medicinal treatments targeting aortic dilatation and dissection consist of agents generally used to lower blood pressure and/or the inotropic state of the heart. By these means, the cyclic repetitive forces exerted on the aortic wall are diminished and thus the onset of aortic dilatation is potentially prevented. Although these pharmacological agents may offer some benefit in reduction of aortic aneurysm expansion rate, they do not target the underlying cause of the progressive aortic degradation.

AREAS COVERED

This review discusses the effectiveness of frequently prescribed medications used to prevent and delay aortic complications in Marfan syndrome. New insights on the biochemical pathways leading to aortic disease are also discussed to highlight new targets for pharmacological therapy.

EXPERT OPINION

Recent insights in the transforming growth factor beta signaling pathway and inflammatory mechanisms in a well-established mouse model of Marfan syndrome, have led to studies exploring new pharmacological treatment strategies with doxycycline, statins and angiotensin II receptor blockers. Pharmacological therapy is focused more on prevention than on delay of aortic wall pathology in Marfan syndrome. Of the new pharmacological treatment strategies targeting aortic pathology in Marfan syndrome, angiotensin receptor type 1 blockers are promising candidates, with several clinical trials currently ongoing.

Elastic properties of aortic wall in patients with bicuspid aortic valve by magnetic resonance imaging

Bicuspid aortic valve (BAV) is frequently associated with aortic wall abnormalities, including dilation of the ascending aorta and even dissection. We propose 2 new indexes of aortic wall biophysical properties, the maximum rates of systolic distension and diastolic recoil (MRSD and MRDR, respectively), in patients with BAV and matched control subjects. We evaluated 53 consecutive young patients with BAV (36 males, mean age 16 ± 4 years) with mild aortic valve disease and a control group of 22 age- and gender-matched healthy volunteers. All subjects underwent a cardiac magnetic resonance imaging study that included phase velocity mapping and cine acquisition at several aortic levels. The MRSD and MRDR were measured in the ascending aorta in both patients with BAV and controls. Of the 53 patients with BAV, 26 had enlarged ascending aortas (dilated BAV), and 27 had a normal aortic diameter (nondilated BAV). Compared to controls, the MRSD was significantly lower in the whole BAV group (4.37 ± 1.1 vs 9.1 ± 2.1), in patients with dilated BAV (4.5 ± 1.1 p <0.0001), and in those with nondilated BAV (4.3 ± 1.0, p <0.0001). The MRDR was greater in the whole BAV group (-4 ± 1.2 vs -7.6 ± 2.7, p <0.0001), in the dilated BAV group (-3.9 ± 1.3, p <0.0001), and in the nondilated BAV group (-4.1 ± 1.2, p <0.0001). A receiver operating characteristic curve analysis of MRSD distinguished BAV from controls with 100% sensitivity and 95% specificity. In conclusion, MRSD and MRDR were slower in the patients with BAV than in the controls, regardless of the dimensions of the ascending aorta.

Factors influencing prognosis in patients with marfan syndrome after aortic surgery

OBJECTIVE

Aortic aneurysm formation leading eventually to aortic rupture or dissection in early adult life is a fatal outcome of Marfan syndrome (MFS). Advances in the treatment of the syndrome have improved prognosis, but the long-term reoperation rate is still high. It remains unknown which factors influence the long-term prognosis, including the reoperation and mortality rates, in surgically treated Chinese patients with MFS. The authors studied 125 such patients to investigate factors influencing prognosis after aortic surgery.

DESIGN

A retrospective clinical investigation.

SETTING

An academic medical center.

SUBJECTS

One hundred twenty-five Marfan patients who had undergone aortic surgery.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The indications for aortic surgery were aortic aneurysm and/or dissection in the 125 Marfan patients. The most commonly performed procedure was the Bentall in 92 patients. Sixteen patients underwent total arch replacement combined with stented elephant trunk implantation. Ten patients underwent the David procedure. Overall in-hospital and 30-day mortality rate was 1.6%. The survival rate was 97.5%, 91.4%, and 74.2% at 1, 5, and 10 years after surgery, respectively. The reoperation rate was 2.5%, 12.9%, and 32.9% at 1, 5, and 10 years after surgery, respectively. Multivariate analysis revealed that increased systolic blood pressure (Sys BP) was the predictor of death (p < 0.05), and body mass index and smoking were significant predictors of reoperation (p < 0.05).

CONCLUSIONS

The present findings report the factors influencing the prognosis of Chinese patients with MFS after aortic surgical procedures. Managing these risk factors may enable health care professionals to improve the prognosis of MFS patients after aortic surgical procedures.

Arterial stiffness in the young: assessment, determinants, and implications

Arterial stiffness describes the rigidity of the arterial wall. Its significance owes to its relationship with the pulsatile afterload presented to the left ventricle and its implications on ventricular-arterial coupling. In adults, the contention that arterial stiffness as a marker and risk factor for cardiovascular morbidity and mortality is gaining support. Noninvasive methods have increasingly been adopted in both the research and clinical arena to determine local, segmental, and systemic arterial stiffness in the young. With adoption of these noninvasive techniques for use in children and adolescents, the phenomenon and significance of arterial stiffening in the young is beginning to be unveiled. The list of childhood factors and conditions found to be associated with arterial stiffening has expanded rapidly over the last decade; these include traditional cardiovascular risk factors, prenatal growth restriction, vasculitides, vasculopathies associated with various syndromes, congenital heart disease, and several systemic diseases. The findings of arterial stiffening have functional implications on energetic efficiency, structure, and function of the left ventricle. Early identification of arterial dysfunction in childhood may provide a window for early intervention, although longitudinal studies are required to determine whether improvement of arterial function in normal and at-risk paediatric populations will be translated into clinical benefits.

Long-term effects of losartan on structure and function of the thoracic aorta in a mouse model of Marfan syndrome

BACKGROUND AND PURPOSE

During development of thoracic aortic aneurysms in a mouse model of Marfan syndrome, upregulation of matrix metalloproteinase (MMP)-2 and -9 was accompanied by compromised aortic constriction and endothelium-dependent relaxation. Losartan has been proposed for the prevention of thoracic aortic aneurysm. We hypothesized that losartan would suppress MMP-2/-9 activation and improve aortic vasomotor function in this model.

EXPERIMENTAL APPROACH

A well-characterized mouse model of Marfan syndrome (Fbn1(C1039G/+)) was used. Starting at 6 weeks old, Marfan mice were untreated or given losartan (0.6 g.L(-1) in drinking water, n= 30). The littermate Fbn1(+/+) mice served as control. Thoracic aortas were studied at 3, 6 and 9 months by histology and by contractility assays in isolated segments in vitro.

KEY RESULTS

Losartan improved elastic fibre organization and increased aortic breaking stress. Losartan reduced the activity and protein expression of MMP-2 and MMP-9 at all ages. Aortic constriction in response to membrane depolarization or phenylephrine was increased by losartan at 3 and 9 months by 100-200%. Active force of aortic smooth muscle was also increased at 6 and 9 months. Acetylcholine-induced endothelium-dependent relaxation was improved by 30% after 3 months of losartan treatment, but such improvement disappeared with longer duration of treatment, accompanied by reduced phosphorylation of endothelial nitric oxide (NO) synthase(Ser1177), Akt(Thr308) and Akt(Ser473), compared with the control.

CONCLUSIONS AND IMPLICATIONS

Losartan improved the contractile function of aorta and reduced MMP activation. However, the endothelial NO pathway remained suppressed in the thoracic aorta during losartan treatment, which might limit its long-term benefits in Marfan syndrome.

GENETIC INFLUENCES ON THE ARTERIAL WALL

1. Arterial stiffness, which has independent predictive value for cardiovascular events, seems to have a genetic component, largely independent of the influence of blood pressure and other cardiovascular risk factors. 2. In animal models of essential hypertension (stroke-prone spontaneously hypertensive rats and spontaneously hypertensive rats), structural modifications of the arterial wall include an increase in the number of elastin-smooth muscle cell connections and smaller fenestrations of the internal elastic lamina, possibility leading to redistribution of the mechanical load towards elastic materials. These modifications may give rise to mechanisms explaining why changes in arterial wall material accompanying wall hypertrophy in these animals are not associated with an increase in arterial stiffness. 3. In monogenic connective tissue diseases (Marfan, Williams and Ehlers-Danlos syndromes) and the corresponding animal models, precise characterization of the arterial phenotype makes it possible to determine the influence of abnormal, genetically determined, wall components on arterial stiffness. 4. Such studies have highlighted the role of extracellular matrix signalling in the vascular wall and have shown that elastin and collagen not only display elasticity or rigidity, but are also involved in the control of smooth muscle cell function. 5. These data provide strong evidence that arterial stiffness is affected by the amount and density of stiff wall material and the spatial organization of that material.

Endothelial dysfunction and compromised eNOS/Akt signaling in the thoracic aorta during the progression of Marfan syndrome

BACKGROUND AND PURPOSE

Aortic complications account for the major mortality in Marfan syndrome (MFS), a connective tissue disorder caused by mutations in FBN1 encoding fibrillin-1. We hypothesized that MFS impaired endothelial function and nitric oxide (NO) production in the aorta.

EXPERIMENTAL APPROACH

Mice (at 3, 6, 9 and 12 months of age) heterozygous for the Fbn1 allele encoding a cysteine substitution (Fbn1 (C1039G/+), Marfan mice, n=75), the most common class of mutation in MFS, were compared with age-matched control littermates (n=75). Thoracic and abdominal aortas from the two groups were studied.

KEY RESULTS

Isometric force measurements revealed that relaxation to ACh (but not to sodium nitroprusside) was diminished in the phenylephrine-precontracted Marfan thoracic aorta at 6 months of age (pEC(50)=6.12+/-0.22; maximal response, E(max)=52.7+/-6.8%; control: pEC(50)=7.34+/-0.19; E(max)=84.8+/-2.2%). At one year, both inhibition of NO production with N(omega)-nitro-L-arginine methyl ester, or denudation of endothelium increased the phenylephrine-stimulated contraction in the control thoracic aorta by 35%, but had no effect in the Marfan aorta, indicating a loss of basal NO production in the Marfan vessel. From 6 months, a reduced phosphorylation of endothelial NOS (eNOS)(Ser1177) and Akt(Thr308) detected by Western blotting was observed in the Marfan thoracic aorta, which was accompanied by decreased levels of cGMP. Expressions of Akt and eNOS in the abdominal aorta were not different between the two groups.

CONCLUSIONS AND IMPLICATIONS

MFS impairs endothelial function and signaling of NO production in the thoracic aorta, suggesting the importance of NO in the age-related progression of thoracic aortic manifestations.

Effect of beta-blockade on ascending aortic dilatation in children with the Marfan syndrome

Aortic root dilatation is the principal life-threatening complication in Marfan syndrome, leading to aortic regurgitation, dissection, and rupture. Beta blockade slows aortic dilatation in adults, but there has been no definitive evidence in children. Therefore, the evolution of aortic diameter at the level of the sinuses of Valsalva in 155 children (82 males, 73 females) aged <12 years who had been diagnosed with Marfan syndrome according to international criteria was retrospectively studied. Affected children treated by beta blockade >or=1 time during their lives (n = 77, mean age at diagnosis 6.1 +/- 3.2 years) were compared with affected children who had never received beta blockers (n = 78; 42 males, mean age 7.4 +/- 5.2 years). A mean delay of 1.3 years was observed between diagnosis and the initiation of beta blockade in the treated group (mean age at initiation 7.5 years). At the time of diagnosis, aortic diameters were similar in the 2 groups, but after 1.3 years, aortic diameters were greater in the group of children in whom beta blockers had been initiated. On univariate analysis, aortic diameter was related to age and height, but not gender or familial history of aortic dissection. On multivariate analysis, treatment and age remained significant determinants of aortic diameter. Beta blockade significantly decreased the rate of aortic dilatation at the level of the sinuses of Valsalva by a mean of 0.16 mm/year (p <0.05), an effect that increased with treatment duration. A trend toward lower cardiac mortality, decreased need for preventive aortic surgery, and less dissection was observed. In conclusion, beta blockade appears to limit aortic dilatation during childhood in patients affected by Marfan syndrome. Therefore, this treatment should be recommended as soon as the diagnosis is made.

Beta-blocker therapy does not alter the rate of aortic root dilation in pediatric patients with Marfan syndrome

OBJECTIVE

To test the hypothesis that chronic beta-blocker therapy in pediatric patients with Marfan syndrome alters the rate of aortic root dilation. Beta-blockade has been advocated as preventive therapy for Marfan syndrome based on reports indicating a decreased rate of aortic root dilation in treated patients.

STUDY DESIGN

Patients with Marfan syndrome (n = 63) followed at Children's Hospital of Pittsburgh or Children's Hospital of New York-Presbyterian who had > or =18 months of echocardiographic follow-up were studied. All clinical data and 213 serial echocardiograms were reviewed, and aortic root dimensions were measured. Patients were divided into 2 groups for comparison: untreated (n = 34) and treated (n = 29).

RESULTS

At study entry, the 2 study groups were comparable in terms of age, sex, body surface area (BSA), aortic root measurements, heart rate, and corresponding z scores. Follow-up duration in each group was similar. At last follow-up, heart rates and heart rate z scores were lower in the treated group. Rates of change of aortic root measurements (P = .52) and the corresponding z scores were not statistically different between the 2 group at the study's end.

CONCLUSIONS

This study suggests that that beta-blocker therapy does not significantly alter the rate of aortic root dilation in children with Marfan syndrome. Based on these data, the recommendation of lifetime beta-blocker therapy instituted during childhood should be reassessed.

Different patterns of aortic wall elasticity in patients with Marfan syndrome: A noninvasive follow-up study

OBJECTIVE

Aortic complications determine the life expectancy of most patients with Marfan syndrome. To find out whether there is heterogenous aortic involvement among patients and, if there is, to characterize aortic patterns and response to long-term beta-blocker therapy, we investigated aortic elastic properties before and during beta-blocker treatment.

METHODS

In 46 patients with Marfan syndrome (age, 17.4 +/- 11.1 years) and 46 healthy control subjects, ascending and descending aortic elastic parameters were determined noninvasively before and after 39 +/- 16 months of beta-blocker treatment with atenolol.

RESULTS

Aortic diameters and distensibility distinguished Marfan patients and controls with a sensitivity of 85% and a specificity of 87%. Cluster analysis revealed 4 patterns of aortic phenotypic expression: (1) reduced ascending aortic elasticity (46% of patients), (2) diminished ascending and descending aortic elasticity (17%), (3) minimal alterations of ascending and descending aortic elasticity (20%), and (4) reduced descending aortic elasticity (17%). During follow-up, aortic elastic properties improved in 21 (70%) of 30 patients and deteriorated in 9 (30%) irrespective of beta-blocker dosage. Improvement was observed in 100% of patients (n = 7; age, 5.3 +/- 4.2 years) with end-diastolic aortic root diameters between 20 and 30 mm and in 61% of patients (14/23; age, 20.5 +/- 10.0 years) with root diameters between 30 and 52 mm.

CONCLUSIONS

Aortic elastic parameters distinguish between patients with Marfan syndrome and healthy controls and show the pattern of regional aortic involvement. Improvement or deterioration during follow-up can influence therapeutic decisions to prevent aortic dissection and rupture. Young age, small root diameter, and high distensibility are favorable prognostic factors.

Marfan syndrome: what internists and pediatric or adult cardiologists need to know

Marfan syndrome (MFS) is one of the most frequent connective tissue disorders, showing striking pleiotropism and clinical variability. There is autosomal dominant inheritance with complete penetrance but variable expression. Approximately 25% of MFS patients have no family history of the syndrome and represent sporadic cases due to new mutations. This hazardous condition is often associated with premature cardiovascular death unless surveillance and management are optimized. The fibrillin gene (FBN1) encodes the structure of the connective tissue protein fibrillin. MFS is caused by mutations in the fibrillin gene, located on chromosome 15 at locus 15q21. Fibrillin abnormalities reduce the structural integrity of different body systems, primarily involving the heart valves, blood vessels, lungs, bones, tendons, ligaments, cartilages, eyes, skin, spinal dura and the CNS. Patients with MFS are likely to have too little fibrillin within these structures, resulting in clinically relevant problems. For example, in the aortic wall, deficient fibrillin may trigger progressive aortic ectasia and may result in aortic dissection.

Aortic reflection coefficients and their association with global indexes of wave reflection in healthy controls and patients with Marfan's syndrome

Early return of reflected pressure waves increases the load on central arteries and may increase the risk of aortic rupture in patients with Marfan's syndrome (MFS). To assess whether wave reflection is elevated in MFS, we used ultrasound and MRI to measure central pressure and flow waveforms in 26 patients (13-54 yr of age) and 26 age- and gender-matched controls. Aortic systolic and diastolic cross-sectional areas were measured at the ascending and descending aorta (AA and DA), diaphragm (DIA), and lower abdominal aorta (AB). From these measurements, local characteristic impedance (Z(0-xx)) and local reflection coefficients (Gamma(xx-yy)) were calculated. Calculated global wave reflection indexes were the augmentation index (AIx) and the ratio of backward to forward pressure wave (P(b)/P(f)). The aorta was wider in MFS patients at AA (P < 0.01) and DA (P < 0.01). Aortic pulse wave velocity was 42 cm/s higher in MFS patients (P < 0.05). Z(0-xx) was not different between groups, except at DA, where it was lower in MFS patients. In controls, Gamma(AA-DA) was 0.31 +/- 0.08, Gamma(DA-DIA) was 0.00 +/- 0.11, and Gamma(DIA-AB) was 0.31 +/- 0.16. Mean values of Gamma(xx-yy) were not different between MFS patients and controls. In controls, aging diminished Gamma(AA-DA) but increased Gamma(DIA-AB). Clear age-related patterns were absent in MFS patients. AIx or P(b)/P(f) was not higher in MFS patients than in controls. There were indications for enhanced wave reflection in young MFS patients. Our data demonstrated that the major determinants of AIx were pulse wave velocity and the effective length of the arterial system and, to a lesser degree, HR and P(b)/P(f).

Echocardiographic Doppler assessment of the biophysical properties of the aorta in pediatric patients with the Marfan syndrome

In the Marfan syndrome (MS), aortic root involvement is usually clinically monitored according to the aortic sinus of Valsalva dilation. Using an echocardiographic Doppler method in this cross-sectional study, abnormal biophysical properties of the ascending aorta were found in pediatric patients with MS compared with healthy controls but not consistently in association with the aortic sinus of Valsalva dilation.

Diagnostic power of aortic elastic properties in young patients with Marfan syndrome

BACKGROUND

In patients with Marfan syndrome, progressive aortic dilation implicates a still-unpredictable risk of life-threatening aortic dissection and rupture. We sought to quantify aortic wall dysfunction noninvasively, determine the diagnostic power of various aortic parameters, and establish a diagnostic model for the early detection of aortic abnormalities associated with Marfan syndrome.

METHODS

In 19 patients with Marfan syndrome (age, 17.7 +/- 9.5 years) and 19 age- and sex-matched healthy control subjects, computerized ascending and abdominal aortic wall contour analysis with continuous determination of aortic diameters was performed out of transthoracic M-mode echocardiographic tracings. After simultaneous oscillometric blood pressure measurement, aortic elastic properties were determined automatically.

RESULTS

The following ascending aortic elastic parameters showed statistically significant differences between the Marfan group and the control group: (1) decreased aortic distensibility ( P < .001), (2) increased wall stiffness index ( P < .01), (3) decreased systolic diameter increase ( P < .01), and (4) decreased maximum systolic area increase ( P < .001). The diagnostic power of all investigated parameters was tested by single logistic regression models. A multiple logistic regression model including solely aortic parameters yielded a sensitivity of 95% and a specificity of 100%.

CONCLUSIONS

In young patients with Marfan syndrome, a computerized image-analyzing technique revealed decreased aortic elastic properties expressed by parameters showing high diagnostic power. A multiple logistic regression model including merely aortic parameters can serve as useful predictor for Marfan syndrome.

Aortic pressure-area relation in Marfan patients with and without beta blocking agents: a new non-invasive approach

OBJECTIVE

To investigate the heterogeneous response to beta blockade in patients with Marfan syndrome by non-invasive assessment of the aortic pressure-area curve.

DESIGN AND PATIENTS

25 patients with the Marfan syndrome who used beta blocking agents (mean (SD) age, 29 (10) years; 20 men, five women), seven without beta blockade (34 (14) years; five men, two women), and 10 controls (29 (5) years; seven men, three women) underwent magnetic resonance imaging and non-invasive continuous blood pressure measurement. Pressure-area curves were constructed at the level of the descending thoracic aorta. A transition point was defined as the pressure at which the pressure-area relation deviated from its elastic (linear) to the collagen (exponential) course.

SETTING

Tertiary referral centre for adult congenital heart disease.

RESULTS

In six patients (five with and one without beta blockade), a transition point in the pressure-area curve was observed, indicating that the load bearing component was not only elastin but also collagen. In the remaining 26 Marfan patients and in the control subjects a linear pressure-area relation was observed.

CONCLUSIONS

This new non-invasive method to derive aortic pressure-area curves showed that most patients with Marfan syndrome have a similar pressure-area curve to controls with similar blood pressures. Five patients on beta blockade showed a transition point in the pressure-area curve which could play a crucial role in the heterogeneous response to beta blocker treatment in Marfan patients. Patients with a transition at low blood pressures may not benefit from beta blocking agents.

Biophysical properties of the normal-sized aorta in patients with Marfan syndrome: evaluation with MR flow mapping

PURPOSE

To investigate the feasibility of magnetic resonance (MR) flow mapping in the assessment of aortic biophysical properties in patients with Marfan syndrome and to detect differences in biophysical properties in the normal-sized aorta distal to the aortic root between these patients and matched control subjects.

MATERIALS AND METHODS

Seventy-eight patients with Marfan syndrome with aortic root dilatation and 23 matched control subjects underwent MR flow mapping in four locations in the normal-sized aorta (1, ascending aorta; 2, thoracic descending aorta; 3, descending aorta at the level of the diaphragm; and 4, abdominal descending aorta). Distensibility at each location and flow wave velocity between locations were calculated.

RESULTS

Compared with the control subjects, patients with Marfan syndrome had decreased aortic distensibility at three of the four locations (levels 1, 2, and 4; P <.05) and increased flow wave velocity between all locations (P <.05) in the aorta. In patients with Marfan syndrome, flow wave velocity was also significantly increased along the entire aortic tract beyond the aortic root (from level 1 to level 4).

CONCLUSION

MR imaging reveals abnormal biophysical properties of the normal-sized aorta in patients with Marfan syndrome. Monitoring of these properties is relevant for evaluating disease progression and treatment options.

Sports and marfan syndrome: awareness and early diagnosis can prevent sudden death

Marfan syndrome is an autosomal dominant disorder of the connective tissues. Its major manifestations are in the cardiovascular, musculoskeletal, and ocular systems. Recognizing the phenotypic presentation of tall stature, long limbs and fingers, chest deformity, myopia, midsystolic click, and systolic or diastolic murmur can lead to early diagnosis. Morbidity and mortality are primarily caused by cardiovascular involvement. The goal of medical therapy is to retard the aortic root dilation that leads to sudden death from dissection or rupture. Surgical interventions for mitral valve regurgitation and resection of aortic aneurysms are highly effective. In addition, individuals with Marfan syndrome should be restricted from participation in certain sports.

Chronic beta-blocker therapy improves outcome and reduces treatment costs in chronic type B aortic dissection

OBJECTIVES

To compare the medical treatment of chronic type B aortic dissection with beta-blockers versus other antihypertensive treatments in terms of their requirement for surgical intervention and treatment costs.

METHODS

Case records of the 130 patients treated for aortic dissection type B in this unit between 1988 and 1997 were reviewed. Seventy-eight of 130 patients with chronic dissection have received isolated medical treatment. Seventy-one of 78 patients were discharged alive. Fifty-one of 71 received beta-blocker treatment, 20/71 were treated with other antihypertensive drugs.

RESULTS

Surgery for aortic dissection became necessary in 20/71 patients (28%) during follow-up (mean, 4.2 years): 10/51 in the beta-blocker group and 9/20 in the other antihypertensive drug group. The freedom from subsequent aortic operation was 80 and 47%, respectively (P=0.001). Indications for emergency surgery were increased aortic diameter (79%), symptomatic aortic aneurysm (11%), and renal artery hypoperfusion (5%). The median hospitalization time during follow-up (dissection-related) was 2 days for patients who received beta-blockers and 16 days for patients who received other antihypertensive drug treatments (P=0.001). The cost of treatment/patient per year amounted to 644 and 12748 euros, respectively.

CONCLUSIONS

A substantial proportion of patients with chronic type B dissection who receive initial medical management will later need surgery. Long-term treatment with beta-blockers reduces the progression of aortic dilatation, the incidence of subsequent hospital admissions, as well as the incidence of late dissection-related aortic procedures and the cost of treatment. Patients with chronic type B dissection need, in addition to frequent follow-up of aortic diameter, continuous treatment with beta-blocking agents.

The Marfan syndrome

The Marfan syndrome (MFS), initially described just over 100 years ago, was among the first conditions classified as a heritable disorder of connective tissue. MFS lies at one end of a phenotypic continuum, with people in the general population who have one or another of the features of MFS at the other end, and those with a variety of other conditions in between. Diagnosis of MFS and these other conditions remains based on clinical features. Mutations in FBN1, the gene that encodes fibrillin-1, are responsible for MFS and (in a few patients) other disorders in the continuum. In addition to skeletal, ocular, and cardiovascular features, patients with MFS have involvement of the skin, integument, lungs, and muscle tissue. Over the past 30 years, evolution of aggressive medical and surgical management of the cardiovascular problems, especially mitral valve prolapse, aortic dilatation, and aortic dissection, has resulted in considerable improvement in life expectancy.

Peripheral resistance vessel dysfunction in Marfan syndrome

BACKGROUND

Patients with Marfan syndrome show a hereditary abnormality of elastin metabolism that may cause aortic enlargement and dissection. We have hypothesized that abnormal elastin may alter peripheral vascular structure and function.

METHODS

Forearm blood flow (FBF) (in milliliters per minute per 100 mL) response to the endothelium-dependent dilator acetylcholine (0.75 to 4.5 microg/min per 100 mL), the endothelium-independent dilator sodium nitroprusside (0.05 to 0.3 microg/min per 100 mL), and structure-related maximum dilator response (10-minute occlusion-induced reactive hyperemia) were measured by plethysmograph in 10 patients with Marfan syndrome (mean age 44 years) and 10 healthy age- and sex-matched controls. Patients with the complications of hypercholesterolemia, diabetes mellitus, or heart failure were excluded from the study.

RESULTS

Basal FBF (mean +/- SE) did not differ between the 2 groups (2.7 +/- 0.3 vs 2.3 +/- 0.4). Maximum FBF response to acetylcholine in patients with Marfan syndrome was significantly lower than that of healthy controls (8.5 +/- 2.1 vs 15.4 +/- 1.7 mL/min per 100 mL; P <.05). Reactive hyperemia was also lower in patients with Marfan syndrome (at peak 23.0 +/- 2.5 vs 29.5 +/- 2.3 mL/min per 100 mL; P <.05), but sodium nitroprusside-induced FBF changes did not differ between the 2 groups (10.3 +/- 1.1 vs 10.2 +/- 1.5 mL/min per 100 mL; P = not significant).

CONCLUSION

These observations suggest that endothelium-dependent dilation and maximum dilator reserve capacity are both abnormal in peripheral resistance vessels of patients with Marfan syndrome. These peripheral vasomotion abnormalities may have a detrimental impact on the cardiovascular system in this disorder.

The genetic basis of aortic disease. Marfan syndrome and beyond

The Marfan syndrome and related disorders are systemic disorders of connective tissue. Proximal aorta is usually dilated. The molecular basis of Marfan syndrome has been elucidated, thus allowing prenatal diagnosis. Life expectancy has markedly improved due to the widespread use of beta-adrenergic receptor inhibitors and improved surgical management of the aortic disease.

Medical treatment of the aorta. I

Diseases of the thoracic aorta are serious conditions that require close observations. Impressive advances in imaging modalities such as magnetic resonance imaging, computed tomography sacs, and transesophageal echocardiography have aided diagnosis and provided insights into the pathogenesis and natural history of thoracic aortic aneurysms, dissection, and atherosclerosis. The current review highlights the etiology, epidemiology, and pathophysiology of these disorders and focuses on the diagnostic approach and suggested medical therapies in the current era.

Effect of long-term beta-blockade on aortic root compliance in patients with Marfan syndrome

BACKGROUND

This study was undertaken to assess the effect of long-term beta-blockade on the aortic root stiffness index and distensibility in patients with Marfan syndrome.

METHODS

Aortic root stiffness index and distensibility were calculated according to the formulas of Stefanadis and Hirai, respectively, with 2-dimensional guided M-mode echocardiogram before and after an average of 26 months of atenolol administration.

RESULTS

Twenty-three asymptomatic patients were studied (11 men and 12 women, aged 31 +/- 14.2 years). The follow-up was 4 +/- 2.2 years. The dose of atenolol was individualized (mean 43.5 +/- 21.6 mg/d). Heart rate decreased from 79 +/- 9 beats/min to 64 +/- 9 beats/min (P =. 01), and systolic blood pressure decreased from 124 +/- 13 mm Hg to 114 +/- 2 mm Hg (P =.01). Distensibility increased from 1.85 +/- 0. 70 x 10(-6) cm2/dynes-1 to 2.21 +/- 0.76 x 10-6 cm2/dynes-1 (P =.02), and the stiffness index decreased from 9.68 +/- 3.78 to 8.85 +/- 3. 15 ( P =.2). Two groups of responses to treatment were identified. Compared with baseline values 15 (65%) patients who responded to treatment had increased distensibility and decreased stiffness index of the aortic root (P =.05). Eight patients (35%) who did not respond to treatment had no significant change. Body weight >91 kg and baseline end-diastolic aortic root diameter >40 mm were significantly associated with no response (P =.05). Two patients in the nonresponding group had echocardiographic progression of aortic insufficiency.

CONCLUSIONS

There was a heterogeneous response in the aortic root elastic properties after long-term treatment with atenolol in asymptomatic patients with Marfan syndrome. Stiffness index and distensibility are more likely to respond when the baseline end-diastolic aortic root diameter is <40 mm.

Phenotypic features and impact of beta blocker or calcium antagonist therapy on aortic lumen size in the Marfan syndrome

Systematic, prospective data regarding phenotypic features, including echocardiographic findings, in pediatric patients with the Marfan syndrome are lacking. In addition, limited and conflicting information exists regarding the impact of pharmacologic therapy on aortic growth rate in children. Fifty-three children and adolescents with the Marfan syndrome underwent physical examination, anthropometric evaluation, and echocardiography. The relation of pharmacologic therapy to aortic growth rate was examined in the 44 subjects in whom serial echocardiograms were recorded. Although boys and girls did not differ in ocular, skeletal, or cardiovascular manifestations, aortic dilatation tended to be more common in boys (86% vs 72%). Children with aortic dilatation at baseline (42 of 53 or 79%) were more likely to also have scoliosis and mitral prolapse (both p <0.005). The medicated patients had slower aortic growth than the unmedicated patients with regard to both absolute aortic growth rate (p <0.01) and aortic growth rate adjusted for age and body size (p <0.005). Nevertheless, major cardiovascular complications developed in 5 patients despite long-term pharmacologic therapy. In conclusion, beta-blocker and calcium antagonist therapy retards aortic growth rate in children and adolescents with the Marfan syndrome.

Changes in aortic distensibility and pulse wave velocity assessed with magnetic resonance imaging following beta-blocker therapy in the Marfan syndrome

It has been shown that beta-adrenergic blocking agents may reduce the rate of aortic root dilation and the development of aortic complications in patients with the Marfan syndrome. This may be due to beta-blocker-induced changes in aortic stiffness, of which distensibility and pulse wave velocity are in vivo measurable derivatives. We studied changes in distensibility at 4 levels of the aorta and pulse wave velocity along the entire aorta after 2 weeks of beta-blocker therapy in 6 Marfan syndrome patients and in 6 healthy volunteers, using magnetic resonance imaging (MRI) combined with brachial artery blood pressure measurements. In both groups, mean blood pressure decreased significantly (Marfan: 86 +/- 6 vs 78 +/- 5 mm Hg, p <0.05; control: 80 +/- 8 vs 73 +/- 3 mm Hg, p <0.05) (all data expressed as mean +/- 1 SD). At baseline, the Marfan syndrome patients exhibited decreased distensibility at the level of the ascending aorta (2 +/- 1 vs 6 +/- 2 10(-3)mm Hg(-1), p <0.01) and increased pulse wave velocity (6.2 +/- 0.4 vs 3.9 +/- 0.4 ms(-1), p <0.01) compared with control subjects. Only the Marfan syndrome patients had a significant increase in aortic distensibility at multiple levels and a significant decrease in pulse wave velocity after beta-blocker therapy (ascending aorta distensibility: 2 +/- 1 vs 4 +/- 1 10(-3)mm Hg(-1), p <0.05; abdominal aorta distensibility: 5 +/- 2 vs 8 +/- 3 10(-3)mm Hg(-1), p <0.05; pulse wave velocity: 6.2 +/- 0.4 vs 5.0 +/- 1.0 ms(-1), p <0.05). Thus, aortic stiffness in Marfan syndrome, together with mean blood pressure, is reduced by beta-blocker therapy, and MRI is well suited to detect these changes by measuring distensibility and pulse wave velocity.

Heterogeneous aortic response to acute beta-adrenergic blockade in Marfan syndrome

Although prophylactic treatment with beta-blockers is used to retard aortic root dilatation in Marfan syndrome, it is not effective in all patients. To assess the effects of beta-adrenergic blockade on the aorta's elastic properties, aortic stiffness index and distensibility were calculated in 13 patients with Marfan syndrome and 10 control subjects before and after beta-adrenergic blockade. At baseline, patients with Marfan syndrome had a significantly increased stiffness index and decreased distensibility. After beta-adrenergic blockade, 8 patients with Marfan syndrome developed stiffness indexes and distensibility values that were closer to normal, whereas these variables deteriorated in 5 patients. Thus the benefit of beta-adrenergic blockade in Marfan syndrome may be the reduction in pulse pressure and myocardial contractility and also promotion of the elastic properties of the aorta. Moreover, the differential responses of aortic mechanics (normalizing or worsening) to beta-adrenergic blockade may possibly have implications for the prognosis in these patients.

Aortic dissection: a medical perspective

Over the past 3 years, a greater understanding of predisposing factors and the pathology of the aortic wall has yielded more insights into the pathogenesis, as well as into more accurate diagnostic and preventive methods. This update will discuss: (1) the incidence, definition, and recent classification of aortic dissection; (2) epidemiology, medical, and recent surgical series; (3) the pathogenesis and risk factors; (4) clinical features and evolving noninvasive imaging approaches to diagnosis; and (5) management from a medical perspective.

Abnormal mechanical properties of the aorta in Marfan's syndrome

OBJECTIVES

Aortic dilatation, dissection and rupture are among the major causes of death in subjects with Marfan's syndrome. The aim of the study was to investigate the mechanical properties or compliance of the aorta in these subjects and compare them with a healthy age- and sex-matched reference population.

MATERIALS AND METHODS

An ultrasound phase-locked echo-tracking system was used to determine diameter and pulsatile diameter change of the infrarenal aorta in nine subjects with Marfan's syndrome which were then compared with the values for 165 healthy individuals. Compliance, defined as the inverse of Ep (pressure strain elastic modulus) or stiffness (beta), was calculated from pulsatile diameter change and blood pressure obtained by the auscultatory method with a sphygmomanometer. For statistical analysis confidence intervals (95%) obtained from the healthy controls were used for comparison. Analysis of covariance (ANCOVA) was performed for the female patients. The sample size for males (n = 2) was too small for the latter analysis.

RESULTS

Compared with normal subjects and their confidence intervals, subjects with Marfan's syndrome had an increased Ep and stiffness (beta) and decreased strain (fractional diameter change) in the infrarenal aorta. Furthermore, ANCOVA in the female patients showed increased beta (p < 0.01) and Ep (p < 0.01) and a decreased strain (p < 0.001). Aortic diameters, MAP, as well as the pulse pressure, were similar in the two groups.

CONCLUSION

This investigation demonstrates alterations in the mechanical properties of the aorta in Marfan's syndrome in the form of increased stiffness of the aortic wall. This may be of importance in the pathogenesis of aortic dissection and rupture.

Relation between age, arterial distensibility, and aortic dilatation in the Marfan syndrome

This study examined the relations between age, arterial distensibility, and systemic hemodynamics in patients with the Marfan syndrome. The study group included 170 patients referred to a specialist clinic, of whom 55 (age 26 +/- 12 years) were diagnosed as having Marfan syndrome. The remaining 115 patients (age 25 +/- 14 years) formed a control group. Each patient underwent echocardiographic examination, with measurement of ascending aorta diameter at end-diastole and end-systole, and aortic flow velocities. The elastic properties of the aorta were indexed by calculation of aortic distensibility, wall stiffness, and systemic pulse wave velocity. Mean end-diastolic aortic diameter in the Marfan group (38 +/- 9 mm) was greater than that in the controls (26 +/- 4 mm, p < 0.01). Resting heart rate and aortic flow velocities were similar in the 2 groups, but systemic arterial pulse pressure was greater in the Marfan group (50 +/- 12 mm Hg) than in the controls (41 +/- 8 mm Hg, p < 0.01). Aortic diameter increased with age in both groups, but at all ages the Marfan group exhibited greater aortic diameters (p < 0.05). Aortic distensibility was less in the Marfan group (2.6 +/- 1.3 cm2.dynes-1 x10(-6)) than in the controls (6.2 +/- 2.1 cm2.dynes-1 x 10(-6), p < 0.01), and the aortic wall stiffness index was greater in the Marfan group (7.9 +/- 3.4) than in the controls (2.8 +/- 0.6, p < 0.01). Aortic wall stiffness increased with age and aortic diameter, but at all ages the Marfan group exhibited a stiffer aorta for a given diameter than did the controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Progression of aortic dilatation and the benefit of long-term beta-adrenergic blockade in Marfan's syndrome

BACKGROUND

The aortic root enlarges progressively in Marfan's syndrome, and this enlargement is associated with aortic regurgitation and dissection. Long-term treatment with beta-adrenergic blockade, by reducing the impulse (i.e., the rate of pressure change in the aortic root) of left ventricular ejection and the heart rate, may protect the aortic root.

METHODS

We conducted an open-label, randomized trial of propranolol in adolescent and adult patients with classic Marfan's syndrome (32 treated and 38 untreated [control] patients). Aortic-root dimensions and clinical end points (aortic regurgitation, aortic dissection, cardiovascular surgery, congestive heart failure, and death) were monitored for an average of 9.3 years in the control group and 10.7 years in the treatment group. All 70 patients were included in the analysis according to the intention-to-treat principle.

RESULTS

The dose of propranolol was individualized; the mean (+/- SE) dose was 212 +/- 68 mg per day. The mean slope of the regression line for the aortic-root dimensions, which reflect the rate of dilatation, was significantly lower in the treatment group than in the control group (0.023 vs. 0.084 per year, P < 0.001). Clinical end points were reached in five patients in the treatment group and nine in the control group. The Kaplan-Meier survival curve for the treatment group differed significantly from that for the control group during the middle years of the trial and remained better for the treatment group throughout the study.

CONCLUSIONS

Prophylactic beta-adrenergic blockade is effective in slowing the rate of aortic dilatation and reducing the development of aortic complications in some patients with Marfan's syndrome.

The natural history of aortic dilatation in Marfan syndrome

OBJECTIVES

To determine the relationship between age and aortic dilatation in patients with Marfan syndrome and to define the rate of progression of aortic dilatation in these patients.

DESIGN

All patients were evaluated in a multidisciplinary clinic to establish a firm diagnosis of Marfan syndrome. Aortic dimensions were measured by echocardiography and patients with Marfan syndrome were followed up with annual physical and echocardiographic examinations to detect any change in aortic diameter over the subsequent four years.

PATIENTS

One hundred and fifty-seven patients were referred to the clinic for assessment, of whom 40 exhibited diagnostic features of Marfan syndrome. Only 24 of these patients had previously been diagnosed with Marfan syndrome, while 17 other patients, previously diagnosed with Marfan syndrome, had insufficient clinical features to justify the diagnosis.

RESULTS

Among the 40 patients (19 male, 21 female) with Marfan syndrome (mean age, 28 +/- 15 years), the prevalence of cardiovascular abnormalities was 90%. Aortic root dilatation was present in 78% of patients, aortic regurgitation in 28%, mitral valve prolapse in 65% and mitral regurgitation in 35%. Mean aortic root diameter in the Marfan patients (21.4 +/- 4.0 mm/m2 body surface area) markedly exceeded that of age and sex matched controls without Marfan syndrome (14.9 +/- 2.2 mm/m2) and that of first-degree relatives without Marfan syndrome (15.3 +/- 2.9 mm/m2). The occurrence of aortic dilatation in Marfan syndrome was variable, with patients as young as 20 years exhibiting severe dilatation. All patients with Marfan syndrome exhibiting aortic dilatation were advised to take beta-adrenergic blocking drugs, unless contraindicated, in an effort to retard the rate of aortic dilatation. Among 33 patients followed up for at least one year, 14 (42%) exhibited an increase in aortic diameter of at least 2 mm, while 16 of 23 patients (70%) followed up for at least three years exhibited similar progression of aortic dilatation. The overall mean rate of dilatation in the Marfan patients was 1.9 mm per year. Nine patients developed aortic dilatation of more than 50 mm diameter during four years' follow-up and required surgical repair of the aorta. Each of these patients is well at between three months' and four years' follow-up.

CONCLUSIONS

Aneurysmal dilatation of the aorta is a common complication of Marfan syndrome and may become manifest at an early age. Furthermore, aortic dilatation can progress rapidly, even in the absence of symptoms. Individuals with Marfan syndrome should have annual echocardiographic examinations to monitor aortic root dimensions, and those exhibiting rapid progression of aortic dilatation or an aortic root diameter in excess of 50 mm, should be considered for elective composite graft repair of the aorta.