Relation of Arterial Structure and Function to Left Ventricular Geometric Patterns in Hypertensive Adults

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1 JACC Vol. 28, No. 3 Setember 1996: Relation of Arterial Structure and Function to Left Ventricular Geometric Patterns in Hyertensive Adults MARY J. ROMAN, MD, FACC, THOMAS G. PICKERING, MD, PHD, JOSEPH E. SCHWARTZ, PHD, RICCARDO PINI, MD, RICHARD B. DEVEREUX, MD, FACC New York, New York Objectives. The resent study sought to determine whether conduit artery structure and function vary according to the attern of left ventricular adatation to hyertension. Background. Although left ventricular geometric attern has been shown to redict cardiovascular events in hyertension, the arterial status in atients with the different atterns is unknown. Methods. We evaluated arterial structure and function by carotid ultrasound and alanation tonometry in 271 unmedicated hyertensive atients classified by echocardiograhy as having normal ventricular geometry, concentric remodeling, concentric hyertrohy or eccentric hyertrohy. Results. All grous were similar in age, gender distribution and body size. Patients with concentric and eccentric hyertrohy had similar blood ressures (mean 173/100 and 171/99 mm Hg, resectively) and left ventricular mass, but comared with atients with normal left ventricular geometry and concentric remodeling, only those with concentric hyertrohy had increased arterial wall thickness ( vs mm, < 0.05), end-diastolic diameter ( vs mm, < 0.05), cross-sectional area ( vs mm 2, < 0.05) and elastic modulus ( vs dynes/cm , < 0.05). Patients with concentric remodeling and eccentric hyertrohy had similar values for these measures ( and mm, and mm, and mm 2, and dynes/cm , resectively), desite lower systolic blood ressures in the former grou (156/94 mm Hg, < 0.001). The revalence of laque was comarable in atients with concentric (56%) and eccentric (42%) hyertrohy and significantly greater in those with normal geometry (21%). Conclusions. Among atients with generally mild, uncomlicated systemic hyertension, arterial structure and function are most abnormal when concentric left ventricular hyertrohy is resent and may contribute to the more adverse outcome associated with this geometric attern. (J Am Coll Cardiol 1996;28:751 6) Recent studies have challenged the traditional concet that the heart consistently resonds to systemic hyertension by develoing concentric left ventricular hyertrohy and have demonstrated a wider sectrum of left ventricular geometric atterns in hyertensive atients (1 7). Classification of atients based on whether left ventricular muscle mass and the left ventricular wall thickness/chamber radius ratio ( relative wall thickness [8]) are normal or abnormal yields four grous with different left ventricular geometric atterns: normal geometry (normal mass and relative wall thickness), concentric hyertrohy (an increase in both left ventricular mass with normal relative wall thickness), eccentric hyertrohy (increased left ventricular mass with normal wall thickness) and the recently From the Deartment of Medicine and the Cardiovascular Center, The New York Hosital Cornell Medical Center, New York, New York. This study was suorted in art by Grants HL 18323, and from the National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland. Manuscrit received December 27, 1995; revised manuscrit received Aril 8, 1996, acceted Aril 16, Address for corresondence: Dr. Mary J. Roman, Division of Cardiology, Box 222, The New York Hosital Cornell Medical Center, 525 East 68th Street, New York, New York identified attern of concentric left ventricular remodeling (increased relative wall thickness with normal mass [1]). Studies that have groued hyertensive atients by these geometric atterns have revealed distinctive rofiles of systemic hemodynamics (1,5), ambulatory blood ressure (3), lasma volume (9), myocardial erformance (5) and rognosis (2,7). However, no information is currently available on whether hyertensive atients with different left ventricular geometric atterns also differ with regard to the structure and function of their systemic arterial tree. Indirect suort for this ossibility is rovided by evidence from several laboratories of relations between arterial geometry and function and left ventricular structure, which remain significant after adjustment for the effects of age, gender and arterial ressure (10 14). Accordingly, the resent study was undertaken to examine arterial structure and function by ultrasound and alanation tonometry of the extracranial carotid arteries in unmedicated hyertensive adults with echocardiograhically classified left ventricular geometric atterns. In addition, the relation of left ventricular geometric attern to carotid atherosclerosis was determined in view of the recent observations of increasing risk of stroke with increasing quartile of left ventricular mass (15) 1996 by the American College of Cardiology /96/$15.00 Published by Elsevier Science Inc. PII S (96)

2 752 ROMAN ET AL. JACC Vol. 28, No. 3 ARTERIAL FINDINGS AND VENTRICULAR GEOMETRY IN HYPERTENSION Setember 1996:751 6 and the indeendent association of increased left ventricular mass with the resence of carotid atherosclerosis (14,16). Methods Patients. Hyertensive atients were eligible for the study if they 1) had no clinical evidence of cardiac or cerebrovascular disease; 2) had no evidence of valvular heart disease on imaging and Doler echocardiograhy; 3) were either reviously unmedicated or had been free of antihyertensive medications for at least 3 weeks (with eriods ranging u to 6 years); and 4) had technically satisfactory echocardiograms and carotid ultrasound studies. Hyertension was documented by systolic arterial blood ressure 140 mm Hg ( 160 mm Hg in subjects 65 years old) or diastolic arterial blood ressure 90 mm Hg, or both, on the average of multile determinations by arm-cuff and mercury manometry. Subjects consisted of hyertensive members of a work site based samle of emloyed adults or atients undergoing diagnostic evaluation of their hyertension at The New York Hosital Cornell Medical Center, as reviously described in art (14,17). Echocardiograhic methods. M-mode and two-dimensional echocardiograms were erformed by a skilled research technician using reviously described methods (18). M-mode strichart recordings of the left ventricle on u to six high quality cycles were coded and read blindly by a single investigator (M.J.R.) using a digitizing tablet. Penn convention measurements were used to calculate left ventricular mass (19,20), which was indexed for body surface area. American Society of Echocardiograhy measurements (21) were used for left ventricular chamber diameter, wall thickness and relative wall thickness. When the M-mode beam could not be oriented along the left ventricular minor axis from available chest wall acoustic windows, measurements made by the American Society of Echocardiograhy recommendations for twodimensional echocardiograhy (22) were substituted. Brachial blood ressure was taken at the end of the echocardiograhic examination. Partition values used to classify left ventricular geometric atterns were the same as those reviously used for comarison with ambulatory blood ressures (3). Patients were classified as abnormal if the left ventricular relative wall thickness exceeded 0.41 (1) or if the left ventricular mass index exceeded 108 g/m 2 in women or 118 g/m 2 in men (23). Carotid ultrasound. As reviously described (10,14), a 7.5-MHz dulex transducer was used to scan the common, internal and external carotid arteries for discrete atherosclerotic laques (24). Two-dimensionally guided M-mode recordings of the distal common carotid artery were recorded on videotae and subsequently digitized using a frame grabber and customized software (ARTSS Cornell Research Foundation). Electronic caliers were used to measure the internal diameter (D d ) and far wall intimal-medial thickness (IMT d ) (25) at end-diastole, recognized from the nadir of the simultaneous arterial ressure waveform or the minimal arterial diameter, as well as the diameter at eak systole (D s ). Arterial geometry was further characterized by calculation of the arterial relative wall thickness (RWT art )as RWT art 2 IMT d /D d and of the arterial cross-sectional area (CSA) as CSA IMT d D d /2 2 D d /2 2. Arterial function assessment. A high fidelity arterial ressure waveform was recorded noninvasively by lacing a solidstate Millar transducer over the right common carotid artery while recording M-mode images of the left common carotid artery, as reviously described (26). Orientation and ressure alied to the transducer were adjusted to achieve alanation of the artery between the transducer and the underlying tissue, as has been validated to yield accurate estimates of intraarterial ulse ressure by comarison with simultaneous invasive ressure recordings (27,28). Systolic and diastolic carotid artery ressures were derived by calibrating the electronic mean of the carotid artery ressure waveform using the mean brachial artery ressure derived from the arm-cuff and mercury manometer measurements (26). Arterial strain, the ercent systolic exansion of the arterial lumen, was calculated as Strain D s D d /D d 100. Carotid ressures, D d,d s and IMT d were used to calculate several measures of arterial stiffness. Peterson s elastic modulus (E ) (29) was calculated as E P s P d / D s D d D d, where P s and P d are the carotid systolic and diastolic ressures, resectively. Young s modulus (E) (30) was calculated as E P s P d / D s D d D d D s / IMT d. Carotid artery stiffness was also calculated using a ressureindeendent measure ( ) (31,32): ln P s P d D s D d /D d. These measures rovide indexes of regional arterial stiffness under the vessel s usual loading conditions (E ) or which adjust for the effects of arterial wall thickening (E) and distending ressure ( ). Statistical methods. Statistical analyses were erformed using SPSS, Release 6.1. Data are resented as the mean value SD. Continuous variables were comared by one-way analysis of variance followed by the Scheffé ost hoc test for multile comarisons. The normality of distribution of variables was assessed by the Kolmogorov-Smirnov or Shairo- Wilks test; variables found to deviate from normality were log-transformed before alication of statistical tests. Proortions were comared among grous by the chi-square statistic. The null hyothesis was rejected at Results Patient characteristics (Table 1). The 271 subjects had a mean age of years (range 25 to 88). Patients in the four

3 JACC Vol. 28, No. 3 Setember 1996:751 6 ROMAN ET AL. ARTERIAL FINDINGS AND VENTRICULAR GEOMETRY IN HYPERTENSION 753 Table 1. Demograhic and Clinical s Age (yr) Gender (% male) Race (% white) BSA (m 2 ) BMI (kg/m 2 ) Blood ressure (mm Hg) Systolic * * Diastolic Total cholesterol (mg/dl) HDL cholesterol (mg/dl) Serum creatinine (mg/dl) Smoking (% former or current) * versus normal geometry versus concentric remodeling versus normal geometry. Data are resented as mean value SD or ercent of atients. BSA body surface area; BMI body mass index; HDL high density liorotein. grous characterized by different left ventricular geometric atterns were similar regarding gender distribution, body size, serum liids and smoking history. Although race did not significantly differ among the grous, atients with concentric hyertrohy were redominantly African-American or African-Caribbean. Likewise, there were no differences in serum creatinine in this healthy grou. Patients with either attern of left ventricular hyertrohy had substantially elevated brachial systolic and diastolic ressures. Left ventricular structure (Table 2). By definition, left ventricular mass was increased in the grous with concentric and eccentric hyertrohy, whereas relative wall thickness was increased in the grous with the two concentric atterns. Left ventricular end-diastolic diameter was significantly reduced in the concentric remodeling grou in comarison with the three other grous, whereas left ventricular end-diastolic diameter was significantly increased in the eccentric hyertrohy grou in comarison with all the other grous. Carotid artery structure (Table 3, Fig. 1). Comared with atients with normal left ventricular geometry, only atients with concentric hyertrohy demonstrated significant increases in carotid artery size, as evidenced by end-diastolic diameter, cross-sectional area and intimal-medial thickness. Patients with concentric hyertrohy, likewise, had significant increases in arterial diameter and cross-sectional area comared with those with concentric remodeling. Desite substantially higher systolic and diastolic ressures, arterial structure in atients with eccentric hyertrohy was similar to that in atients with normal geometry and concentric remodeling. The revalence of laque was significantly increased in the two hyertrohy grous. Arterial function (Table 4). Vascular strain was lowest and elastic modulus highest in atients with concentric hyertrohy. However, when structural adatation (wall thickening) and distending ressure were considered by Young s modulus and, resectively, differences between the four grous were no longer statistically significant. Discussion Left ventricular geometry and carotid hyertrohy. Although classification of left ventricular geometric atterns in atients with hyertension strongly redicts the incidence of subsequent vascular events (2,7,33,34), little is known about arterial structure and function in atients with different left ventricular geometric adatations. The rincial new findings Table 2. Left Ventricular Structure and Function End-diastolic diameter (cm) * * * Fractional shortening (%) Setal thickness (cm) * Posterior wall thickness (cm) * Relative wall thickness # # Mass (g) * * Mass index (g/m 2 ) * * * versus concentric remodeling versus normal geometry versus concentric hyertrohy versus normal geometry versus concentric remodeling versus eccentric hyertrohy. # versus eccentric hyertrohy. Data are resented as mean value SD.

4 754 ROMAN ET AL. JACC Vol. 28, No. 3 ARTERIAL FINDINGS AND VENTRICULAR GEOMETRY IN HYPERTENSION Setember 1996:751 6 Table 3. Carotid Artery Structure End-diastolic diameter (mm) * 0.01 Intimal-medial thickness (mm) * Relative wall thickness Cross-sectional area (mm 2 ) * Plaque (%) * 56* * 0.05 versus normal geometry versus concentric remodeling. Data are resented as mean value SD or ercent of atients. in the resent study are that hyertensive atients with concentric left ventricular hyertrohy have a greater increase in arterial wall thickness, cross-sectional area and stiffness at the oerating level of distending ressure than hyertensive atients with other left ventricular geometric atterns, desite similarities between the grous in age, gender distribution and body size. The concentration of arterial abnormalities in atients with Figure 1. Relation of left ventricular geometric attern to common carotid artery structure and revalence of atherosclerosis. concentric left ventricular hyertrohy is articularly notable because our atients with eccentric hyertrohy had equivalent blood ressures. Although there was a trend toward higher mean values of arterial wall thickness, diameter and crosssectional area in the eccentric hyertrohy grou, the values were statistically indistinguishable from those in atients with normal left ventricular geometry and concentric remodeling, desite considerably lower blood ressures in the latter two grous. The revious observation (3) that ambulatory ressures are highest in atients with concentric hyertrohy and are similar in grous with eccentric hyertrohy and concentric

5 JACC Vol. 28, No. 3 Setember 1996:751 6 ROMAN ET AL. ARTERIAL FINDINGS AND VENTRICULAR GEOMETRY IN HYPERTENSION 755 Table 4. Carotid Artery Function Vascular strain (%) * Elastic modulus (dynes/cm ) * Young s modulus (dynes/cm 2 er mm 10 6 ) Stiffness index ( ) * 0.05 versus normal geometry. Data are resented as mean value SD. remodeling may rovide an exlanation for these results. However, among the 173 atients in the current study grou who had ambulatory blood ressure monitoring, awake systolic but not diastolic ressures were significantly increased in both the concentric and eccentric hyertrohy grous versus in those with normal geometry (164/101 and 160/96 mm Hg, resectively, vs. 146/92 mm Hg, 0.05, for systolic ressure). Alternatively, nonhemodynamic stimuli may be imortant. Although it has recently been reorted that the angiotensin I converting enzyme DD genotye is associated with both an increase in common carotid artery intimal-medial thickness (35) and electrocardiograhic evidence of left ventricular hyertrohy (36), it remains to be determined whether there is more likely to be underlying concentric ventricular hyertrohy. The tendency toward a racial difference between the grous also suorts the ossibility of a genetic contribution to the differences in arterial structure. Left ventricular geometry and carotid atherosclerosis. The revalence of laque was highest in the grou with concentric hyertrohy (56%), articularly in comarison with the normal geometry and concentric remodeling grous, desite similarity among grous in age, serum liids and smoking history. In fact, the ercentage of current or former smokers was nearly half as much in the concentric hyertrohy grou, although the difference was not statistically significant by the chi-square test. The higher revalence of laque in both the concentric and eccentric hyertrohy grous is in keeing with our revious observation of an association between carotid atherosclerosis and increasing left ventricular mass index in both normotensive and hyertensive subjects (14). The exlanation for the current finding, and dissociation from the other arterial structural findings, is uncertain but may be at least artially exlained by higher levels of both distending ressure and ulsatile forces resulting in greater suscetibility to endothelial damage. Left ventricular geometry and arterial function. Measures of arterial function generally tended to be more abnormal in hyertensive atients with other geometric adatations than in those with normal left ventricular geometry, but these differences mostly did not attain statistical significance, ossibly because of wide scatter in the data as well as the modest size of some subgrous. The elastic modulus, a measure of vascular stiffness at its oerating level of distending ressure, was significantly elevated in the concentric hyertrohy grou. This finding is comarable to the earlier observation of Boutouyrie et al. (37), that left ventricular mean wall thickness and mass/volume ratio were inversely related to carotid artery distensibility and comliance in a grou of 86 hyertensive atients. Their study did not include measurement of wall thickness or isobaric measures of arterial function; thus, it is uncertain whether their findings are redominantly related to distending ressure, as would aear to be the case in our study grou. Left ventricular geometry and arteriolar disease. Our findings in the carotid artery, reresentative of the large conduit arteries, are comlemented by recent findings in the arteriolar system. In a recent study (38) of 140 Jaanese atients with essential hyertension, 57 (41%) of whom were studied on medications, the atients with concentric hyertrohy (n 20 [14%]) had the highest revalence of grade III or IV retinoathy (53%) comared with those with normal geometry (0%), concentric remodeling (0%) and eccentric hyertrohy (29%, 0.05 for all comarisons). Serum creatinine was likewise highest in the grou with concentric hyertrohy. Left ventricular mass was the strongest multivariate redictor of fundoscoic grade and serum creatinine. These findings are similar to those in our earlier reort of a subgrou of hyertensive atients characterized by increased left ventricular chamber function, more marked concentric left ventricular hyertrohy and greater degrees of fundoscoic abnormalities and roteinuria (39). In the resent study of otherwise healthy hyertensive atients, we detected no differences in serum creatinine among the four grous and did not systematically acquire data on arteriolar disease. Study limitations. The resent study grou consisted overwhelmingly of atients with relatively mild hyertension, reducing the roortion of atients with either concentric or eccentric left ventricular hyertrohy, in contrast to revious studies (1 3,5,6,33). Whether study of hyertensive atients with more ronounced elevations in blood ressure and increases in left ventricular mass or with symtoms of cardiovascular disease would yield similar or even more ronounced results is uncertain. It is also ossible that studying larger oulations would reveal significant abnormalities of arterial geometry and stiffness in atients with eccentric left ventricular hyertrohy. Clinical imlications. Ultrasound imaging of the left ventricle and the extracranial carotid arteries reveals that the sectrum of geometric atterns seen in the heart in hyertension is artially aralleled by structural and functional changes in the arterial tree. In articular, atients with concentric left

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