Left Ventricular Function in Chronic Aortic Regurgitation

Transcription

1 1374 J AM COLL CARDIOL 1983:1(6): Left Ventricular Functin in Chrnic Artic Regurgitatin ABDULMASSIH S. ISKANDRIAN, MD, FACC, A-HAMID HAKKI, MD, FAce, BRUNO MANNO, MD, ANGELO AMENTA, NMT, SALLY A. KANE, RN Philadelphia, Pennsyl vania Left ventricular perfrmance was determined in 42 patients with mderate r severe artic regurgitatin during upright exercise by measuring left ventricular ejectin fractin and vlume with radinuclide ventriculgraphy. Classificatin f the patientsaccrding t exercise tlerance shwed that patients with nrmal exercise tlerance ( ~ 7.0 minutes) had a significantly higher ejectin fractin at rest (prbability [p] = 0.02) and during exercise (p = ), higher cardiac index at exercise (p = ) and lwer exercise end-systlic vlume (p = 0.01 ) than did patients with limited exercise tlerance. Similar significant differences were nted in yunger patients cmpared with lder patients in ejectin fractin at rest and exercise (bth p = 0.001) and cardiac index at rest (p = 0.03) and exercise (p = ). The end-diastlic vlume decreased during exercise in 60% f the patients. The patients with a decrease in vlume were significantly yunger and had better exercise tlerance and a larger end-diastlic vlume at rest than did patients wh shwed an increase in vlume. The mean crrected left ventricular end-diastlic radius/ wall thickness rati was significantly greater in patients with abnrmal than in thse with nrmal exercise reserve (mean ± standard deviatin 476 ± 146 versus 377 ± 92 mm Hg, p < 0.05). Thus, in patients with chrnic artic regurgitatin: 1) left ventricular systlic functin during exercise was related t age, exercise tlerance and crrected left ventricular end-diastlic radius/wall thickness rati, and 2) the end-diastlic vlume decreased during exercise, especially in yunger patients and patients with nrmal exercise tlerance r a large vlume at rest. In 1978, Brer et al. (I) reprted n 43 patients with artic regurgitatin wh were studied at rest and during supine exerci se by means f gated (equilibrium) radinuclide ventriculgraphy. The rest ejectin fract in was nrmal in 21 f 22 asymptmatic patients and in 14 f 21 symptmatic patients. Hwever, the exercise ejectin fractin was nrmal in nly I symptmatic.patient and in nly 13 asymptmatic patients. Dehmer et al. (2) studied 17 patients with artic regurgitatin at rest and durin g supine exercise by means f gated radinucl ide ventriculgraphy. The asymptmatic patient s shwed n significant change in ejectin fractin durin g exercise, whereas the symptmatic patients shwed a significant decrease. Sub sequ ent studies (3,4) shwed that symptmatic patients with artic regurgitatin may have a nrmal ejectin fractin at rest and a nrmal respnse t exerci se. The purpse f this study was t define the factrs Frm the Likff Cardivascular Institute f Hahnemann University and Hspital, Philadelphia, Penn sylvania. Manuscript receiv ed Octber revised manuscript received January , accepted Janua ry Add ress fr reprints: Abdulmassih S. Iskandr ian, MD, Likff Cardivascular Institute, Hahnemann University, 230 Nrth Brad Street, Philadelphi a, Pennsylvania by the Amencan Cllege f Cardilgy that affect left ventricul ar functin and vlume during upright exercise in 42 patients with artic regurgitatin. Methds Study patients. The study grup cn sisted f 42 cnsecutive patients with chrnic artic regurgitatin wh underwent exercise testing in ur labratry. There were 34 men and 8 wmen between the ages f 14 and 69 years (42 ± 16, mean ± standard deviatin). Diagnsis was cnfirmed by cardiac catheterizatin and angigraphy in 33 patient s. The degree f artic regurgitatin was assessed qualitativel y by artgraphy (5) and was fund t be eith er mderate r severe. Crnary arterigraphy was perfrmed in the patients lder than 30 years fage and shwed nrmal results in all. Fur add itinal patients wh had crnary artery disease by crnary arter igraphy were excluded frm this study. One f the 33 patients had assciated mild artic stensis and I had assciated mild mitral regurgitatin. Nrmal sinus rhythm was present in all patients. Artic regurgitatin was presumed t be f cngenital r rheumatic rigin in 32 patients; in I patient it was due t paravalvular leak. In the remaining nine patients, the diagnsis f artic /83/ $03 00

2 LEFT VENTRICULAR FUNCTION IN AORTIC REGURGITATION J AM COLL CARDIOL (6) regurgitatin was made by clinical and echcardigraphic examinatin (6). These patients were asymptmatic. Exercise test prtcl. On the day f exercise testing, a 12 lead electrcardigram was btained and the patient then underwent symptm-limited upright exercise n a bicycle ergmeter (Quintn Instruments). The starting wrk lad was 200 kp-rn/min. The wrk lad was increased gradually until the end pint f exercise (extreme fatigue, leg weakness r dyspnea, r a cmbinatin f these indicatins). During exercise, the patient was seated n a bicycle in frnt f a multicrystal gamma camera (Baird-Atmic System-77). Tw electrcardigraphic leads (CMs and avf) were cntinuusly mnitred during the exercise and recvery perids. Bld pressure was measured by the cuff methd every 2 minutes during the exercise and recvery perids. Radinuclide ventriculgraphy. Befre exercise, a rest first pass radinuclide ventriculgram was perfrmed with a blus injectin f 15 mci f technetium-99m pertechnetate. This was repeated at peak exercise. Data during exercise were btained while the patient cntinued t pedal. The patient's chest was stabilized against a cllimatr as he r she held rails at the sides f the camera's head. Radinuclide ventriculgrams were prcessed with the cmputer sftware incrprated int the Baird-Atmic system (6,7). The validatin f radinuclide-derived measurements has been previusly reprted (3). The lwer limit f a nrmal rest ejectin fractin in ur labratry is 50%. Change in nrmal ejectin fractin respnse t exercise is defined as a 0.05 r greater increase in ejectin fractin frm rest t exercise. Nrmal cntrl subjects. The changes in left ventricular vlume and ejectin fractin in patients with artic regurgitatin during exercise were cmpared with thse seen in 15 nrmal subjects (12 men and 3 wmen) aged 25 t 62 years (mean age 41). These subjects were studied because f atypical angina, but at cardiac catheterizatin their left ventriculgram and crnary angigram were fund t be nrmal. Echcardigraphy. We btained M-mde echcardigrams with the patient in the supine r left lateral decubitus psitin, using an ultrasnscpe with a 2.25 MHz medium (7.5 em) internally fcused transducer. The echcardigrams were recrded n a strip chart. Measurements f the left ventricular psterir wall, septum and cavity dimensin were made at the level f the chrdae tendineae at the nset f the QRS cmplexes (8). The left ventricular radius/wall thickness rati was crrected fr systlic bld pressure by the fllwing: (LVEDD/2 PWTh) X SBP, where LVEDD = left ventricular end-diastlic internal dimensin, PWTh = psterir wall thickness at end-diastle and SBP = systlic bld pressure (4). Statistical analysis. Differences between rest and exercise results were analyzed by means f the paired t test. Differences between grups were analyzed by the analysis f variance r the chi-square test. Results were expressed as the mean ± standard deviatin (SD) when apprpriate. A prbability (p) value f 0.05 r less was cnsidered significant. Results Ejectin fractin. The left ventricular ejectin fractin was nrmal at rest in 20 patients and abnrmal «50%) in the remaining patients. A nrmal rest ejectin fractin with a nrmal respnse t exercise (2: 0.05 increase) was bserved in 10 patients. A nrmal ejectin fractin respnse t exercise (2: 0.05 increase) was seen in eight patients with an abnrmal rest ejectin fractin. Exercise tlerance. With the exercise tlerance f ur nrmal subjects as a base (minimal exercise duratin 7.0 minutes), patients with artic regurgitatin were classified int thse with nrmal exercise tlerance (2: 7.0 minutes) and thse with abnrmal exercise tlerance (exercise duratin < 7.0 minutes). Imprtant differences were nted amng patients with artic regurgitatin when they were gruped accrding t nrmal r abnrmal exercise tlerance (Table 1). Patients with nrmal exercise tlerance were significantly yunger (p = ) and had a higher ejectin fractin at rest (p = 0.02) and during exercise (p = ) (Fig. 1), higher exercise cardiac index (p = ) and lwer exercise end-systlic vlume (p = 0.01) than did patients wh had limited exercise tlerance. Other imprtant differences were nted when the patients were gruped accrding t age (Table 2). Yunger patients had a significantly higher ejectin fractin at rest (p = 0.001) and during exercise (p = 0.001), higher cardiac index at rest (p = 0.03) and during exercise (p = ), lwer bld pressure and better exercise tlerance (p = ) than did lder patients. Left ventricular dimensins. The incidence f left ventricular hypertrphy by electrcardigram was nt significantly different in patients gruped accrding t symptms, age r exercise tlerance. The mean f the crrected left ventricular end-diastlic radius/wall thickness rati was significantly greater in patients wh had an abnrmal ejectin fractin respnse t exercise than in thse wh had a nrmal respnse (476 ± 146 vs. 377 ± 92 mm Hg, p < 0.05). The echcardigraphic measurements f the psterir wall thickness, end-diastlic and end-systlic dimensin are prvided in Table 2. End-diastlic vlume (Table 3). Left ventricular vlume measurements were available in 40 f the 42 patients at rest and during exercise (Fig. 1, Table 3). In cntrast t the nrmal subjects wh shwed either n change r an increase in end-diastlic vlume during exercise (Table 4),

3 1376 J AM COLL CARDIOL 1983; 1(6): ISKANDRIAN ET AL Table 1. Data in Relatin t Exercise Duratin in Patients With Artic Regurgitatin Age(yr) R-EF(%) Ex-EF (0/0) R-EDV (ml) Ex-EDV (ml) R-ESV (ml) EK-ESV (ml) R-CI (liters/min per rrr') Ex-CI (hters/min per m 1 ) R-HR (beats/min) Ex-HR (beats/min) R-SBP (mm Hg) Ex-SBP (mm Hg) R-DBP (mm Hg) Ex-DBP (mm Hg) Ex duratin (min) L. EF (0/0) L. EDV (ml) LV PWTh (mm) LV EDD (mm) LV ESD (mm) < 7.0 min (n = 17) 53 ± ± ± ± ± ± ± 135 *{5.0 ± ± ± 19 *{ 143 ± 39 _{141 ± ± 24 t{ 66 ± ± ± ± ± ± ± ± 1.4 Exercise Duratin (mean ± SD) 2: 7.0 min (n = 25) 35 ± ± ± 14 *{293 ± ± ± ± 67 _{ 5 9 ± ± ± 14 -{ 151 ± 15 _{I27 ± ± ± ± ± ± ± ± ± ± 0.8 p Value (R vs. Ex) *Prbability (p) < t P < t p < CI = cardiac index: DBP = diastlic bld pressure; L. = change; EDD = end-diastlic dimensin: EDV = end-diastlic vlume, EF = ejectin fractin; ESD = end-systlic dimensin; ESV = end-systlic vlume; Ex = exercise; HR = heart rate, LV = left ventricular; n = number f patients, = nt significant; PWTh = psterir wall thickness: R = rest; SBP = systlic bld pressure; SD = standard deviatin. patients with artic regurgitatin shwed a mean decrease in end-diastlic vlume with exercise. The end-diastlic vlume decreased in 24 (60%) f the 40 patients. Patients wh shwed a dectease in end-diastlic vlume were yunger (p < 0.05), had better exercise tlerance (p = 0.04) and had a larger rest vlume (p ;= 0.009) (Table 3). The magnitude f decrease in end-diastlic vlume was significantly greater (p = 0.04) in patients with nrmal exercise tlerance than in patients with reduced exercise tlerance. The change in ejectin fractin during exercise did nt crrelate with the change in end-diastlic vlume (r = 0.44) (Fig. 2). Discussin First pass radinuclide ventriculgraphy with a multicrystal gamma camera has several advantages in evaluating patients with artic regurgitatin. First, it can be easily perfrmed with the patient in the upright psitin. Secnd, data acquisitin time is shrt, and therefre the exercise measurements represent the hemdynamic abnrmalities that ccur at peak exercise, Finally, this methd (as well as gated radinuclide ventriculgraphy) is nninvasive; it has n direct negative intrpic effect n ventricular functin (such as might ccur with cntrast angigraphy), and therefre is useful fr serial measurements. Changes in end-diastlic vlume during exercise. In 1832, Crrigan (9) made the fllwing bservatins: The danger f the disease [artic regurgitatin] is in prprtin t the quantity f bld that regurgitates and the quantity that regurgitates will be large in prprtin t the degree f inadequacy f the valves and t the length f pause between the cntractins f the ventricle during which the bld can be puring back. If the actin f the heart be rendered very slw, the pause after each cntractin will be lng and, cnsequently, the regurgitatin f bld must be cnsiderable. Frequent actin f the heart, n the cntrary, makes the pause after each cntractin shrt, and in prprtin as the pauses are shrtened, the regurgitatin must be lessened. The studies f Judge et al. (10) and Firth et al. (11) cnfirmed Crrigan's hypthesis using atrial pacing. These studies shwed a decrease in left ventricular end-diastlic vlume, but n change in regurgitant fractin. Changes in regurgitant fractin during exercise, hwever, are unknwn. We bserved a decrease in end-diastlic vlume during upright exercise in 60% f ur patients with artic regurgitatin. Patients wh had a decrease in end-diastlic vlume tended t be yunger and t have nrmal execise tlerance and a larger rest vlume. Dehmer et al. (2) bserved that symptmatic patients with artic regurgitatin had an increase in end-diastlic vlume during exercise whereas the asymptmatic patients had variable changes. Hwever, their patients were exercised in the supine psitin. Peter and Jnes (3) bserved that patients with artic regurgitatin and angina had a smaller end-diastlic vlume at rest that

4 "EFf VENTRICULARFUNCTION IN AORTIC REGURGITATION JAM COLL CARDIOL 1983,1(6); ~ - e.-...!-e.-... U Q) '-W 70 -I :E- 60 Q) m (Q 30 E ~ > U 'a 300 I 'a C W ~. 10 L...J L...I 100 '-' '--' Rest Exercise Rest Exercise 600 Figure 1. Changes in ejectin fractin, end-diastlic vlume and end-systlic vlume during exercise in patients with artic regurgitatin. Open circles dente patients with nrmal exercise tlerance and clsed circles dente patients with abnrmal exercise tlerance I :E 400 -Q) E ~ > U ṁ 200 >0- mi 'a CW ~ L..-...I Rest 000 L-..." Exercise did nt change during exercise, but in patients withut angina, the end-diastlic vlume was higher at rest and decreased during exercise. Thus, age, symptms, exercise tlerance, left ventricular size and bdy psitin during exercise may effect marked changes in ventricular vlume during exercise. These results als indicate that changes in left ventricular vlume during exercise are different frm thse during pacing. Exercise-induced changes in left ventricular ejectin fractin. The natural histry f patients with artic regurgitatin is marked by a fairly lng perid during which the patient remains asymptmatic (12-15). During this perid, a gradual increase in left ventricular end-diastlic vlume and left ventricular cmpliance can be seen, with little r n elevatin in left ventricular end-diastlic pressure. Hwever, nce symptms f heart failure appear, there is usually rapid deteriratin in the cnditin f the patient. It has been suggested that since exercise-induced abnrmalities in left ventricular functin precede the abnrmalities at rest, serial studies might be used t indicate the best time fr surgery. Our results, hwever, differ frm thse

5 1378 J AM COLL CARDIOL 1983,1(6)' ISKANDRIAN ET AL Table 2. Data in Relatin t Age in Patients With Artic Regurgitatin s 40 years (n = 19) > 40 years (n = 23) p Value Age (yr) R-EF (%) Ex-EF (%) R-EDV (m!) Ex-EDV(ml) R-ESV (ml) Ex-ESV (ml) R-C! (liters/rmn per rrr') Ex-C) (liters/min per rrr' ) Ex-HR (beats/min) R-SBP (mm Hg) Ex-SBP (mm Hg) R-DBP (mm Hg) Ex-DBP (mm Hg) Ex duratin (min) LV PWTh (mm) LV EDD (mm) LV ESD (mm) 28 :!: 8 57 :!: :!: 12 t{300 :!: :!: :!: :!: :!: 2.3 { 11.2 :!: :!: :!: 20 { 173:!: :!: :!: :!: 3.5 I I :!: :!: :!: :!: 9 45 :!: :!: :!: :!: :!: :!: 123. { 4.9 :!: :!: :!: 33.{141 :!: :!: 21.{ 70 :!: :!: :!: :!: :!: :!: *p < 0.00 I. t p < Abbreviatin s as in Table I. f Brer et al. (1) and Dehmer et al. (2). In ur study, nrmal left ventricular respnses during exercise were seen in the presence f abnrmal functin at rest in bth symptmatic and asymptmatic patients. Similar results have been reprted by thers (3,4). The difference between ur results and thse f Brer et al. (1) and Dehmer et al. (2) may be related t the type f exercise, which was upright in ur study (as well as in the studies f Lewis et a1. [4] and Peter and Jnes [3]) and supine in the ther studies. Previus studies (16-18) shwed imprtant hemdynamic differences between supine and upright exercise. Furthermre, it is pssible that the symptms in sme patients might have been exaggerated by fear r anxiety, as well as by the uncertainty f the treating physician in many circumstances. It may be equally true that denial f symptms because f fear f surgery r change in life style may have affected ur classificatin f patients. Therefre, ne imprtant implicatin f exercise testing may be t stratify patients by bjective data based n their exercise tlerance. Thus, patients with nrmal exercise tlerance had a higher rest and exercise ejectin fractin, lwer exercise end-systlic vlume and higher exercise cardiac index than did patients with reduced exercise tlerance (Table 1). Left ventricular dilatin at rest was similar in patients with nrmal r abnrmal exercise tlerance. Hwever, the end-diastlic vlume decreased during exercise in patients with nrmal exercise tlerance and remained unchanged in the remaining patients. Accrding t the pressure-vlume relatin, it is pssible that the decrease in vlume acts as a prtective mechanism by limiting the increase in left ventricular filling pressure and thus imprving exercise capacity. Age, and hence duratin f disease, als had an imprtant effect n left ventricular functin; yunger patients had higher rest and exercise ejectin fractin s and cardiac index, better Table 3. Cmparisn Between Patients With a Decrease and Thse With an Increase in End-Diastlic Vlume During Exercise Decrease (n = 24) Increase (n = 16) P Value Age (yr) Ex duratin (min) R-HR (beats/min) Ex-HR (beats/min) R-EF (%) Ex-EF (%) R-EDV (ml) Ex-EDV (ml) R-ESV (ml) Ex-ESV (m!) 38 :!: :!: :!: 1O { 148 :!: :!: :!: :!: :!: :!: :!: :!: :!: :!: 23 *{ 146:!: :!: 9 50:!: :!: :!: :!: :!: 60 < *p < Abbreviatins as in Table I.

6 LEFr VENTRICULAR FUNCTION IN AORTIC REGURGITATION J AMCOLL CARDIOL 1983:1(6): Table 4. Hemdynamic Measurements at Rest and During Exercise in 15 Nrmal Subject s Measurement Rest Exercise p Value HR (beats/min) 79 ± II 157 ± 14 < SBP (mm Hg) 122 ± ± 25 < DBP (mm Hg) 82 ± ± 12 < 0.02 EF (%) 61 ± 6 73 ± 5 < EDVI (ml/m-) 78 ± ± 14 ESVI (mllm 2 ) 3 1 ± 9 25 ± 10 CI (Iiters/mm per m 2 ) 3.0 ± ± 1.8 < Ex duratin (min) 9. 9 ± 2.6 EDVI = end-diastlic vlume index ; ESVI = end-systlic vlume index; ther abbreviatins as in Table I exercise tlerance and lwer bld pressure than did lder subjects (Table 2). Rle f left ventricular hypertrphy and wall stress. Studies in patients with cngestive cardimypathy have demnstrated that the extent f left ventricular hypertrphy rather than ventricular dilatin is linked t survival (19 21). Benjamin et al. (19) suggested a mre favrable prgnsis in patient s in whm there is evidence f left ventricular hypertrphy. They prp sed a left ventricular hypertrph y dilatin index (average left ventricular wall thickness/maximalleft ventricular cavity diameter) t differentiate patients with cngestive cardimypathy and shrt-term survival frm patients with lng-term survival. Electrcardigraphic evidence f left ventricular hypertrph y, hwever, was f limited value in making a prgnsis. Our data demnstrate that in patients with chrnic artic regurgitatin, the crrected left ventricular radius/wall thickness rati was significantly greater in patients wh had an abnrmal ejectin fractin respnse t exercise than in patients wh had a nrmal respnse. This finding is in agreement with the results f Lewis et al. (4). This rati represents vlume/mass rati and, accrd ing t the Laplace relatin, the wall stress remains nrmal as lng as the hypertrph y is prprtinal t dilatin (22). Clinical implicatins. Exercise testing is useful in patients with artic regurgitatin t categrize them accrdin g t their exercise tleranc e, which can be used t predict left ventricular perfrmance bth at rest and during exercise. The presence f depressed ventricular functin at rest des nt preclude a nrmal ejectin fractin respnse t exercise. Figure 2. Crrelatin between changes in ejectin fractin ( ~EF) and percents f change in end-dia stlic vlume (~EDV) in patients with artic regurgitatin. Opencircles dente patients with nrmal exercise tlerance and clsed circles dente patients with abnrmal exercise tlerance. l u w 5 <l r = \-f e-----i&-t~---:::-:---- ee -5 I -30 I I Ll EDV (%) 0 1' I 30 References I. Brer JS, Bacharach SL, Green MV, et al. Exercise-induced left ventricular dysfunctin in symptmatic and asymptmatic patients with artic regurgitatin: assessment with radinuclide cineangigraphy. Am J Cardil 1978;42: Dehmer GJ, Firth BG, Hil1is LD, et al. Alteratins in left ventricular vlumes and ejectin fractin at rest and during exercise in patients with artic regurgitati n. Am J Cardil 1981;48: Peter CA, Jnes RH. Cardiac respnse t exercise in patients with chrnic artic regurgitatin. Am Heart J 1982; I04: Lewis SM, Riba AL, Berger HJ, et al. Radinuclide angigraphic exercise left ventricular perfrmance in chrnic artic regurgitatin: relatinship t resting echgraphic ventricular dimensins and systlic wall stress index. Am Heart J 1982;103: Lehman JS, Byle 11, Debbas IN. Quantitatin f artic valvular insufficiency by catheter thracic artgraphy. Radilgy 1962;79: Iskandrian AS, Hakki A-H, Kane S, Segal BL. Quantitative radinuclide angigraphy in assessment f hemdynamic changes during upnght exercise: bservatins in nrmal subjects, patients with crnary artery disease, and patients with artic regurgitatin. Am J Cardil 1981;48: Rerych SK, Schlz PM, Newman GE, Sabistn DE Jr. Jnes RH. Cardiac functin at rest and during exercise in nrmals and in patients with crnary heart disease: evaluatin by radinuclide angicardigraphy. Ann Surg 1978;187: Sahn OJ, DeMaria A, Kissl J, Weyman A. The Cmmittee n M Mde Standardizatin f the American Sciety f Echcardigraphy. Recmmendatins regardin g quantitatin in M-mde echcardi gra-

7 1380 J AM cu, CARDIOl 1983;1(6): ISKANDRIAN ET AL phy: results f a survey f echcardigraphic measurements. Circulatin 1978:58: COrrigan OJ. On permanent patency f the muth f the arta r inadequacy f the artic valves. Edinburgh Med Surg J 1832: Judge TP, Kennedy JW, Bennett LJ, Wils RE. Murray JA, Blackmn JR. Quantitative hemdynamic effects f heart In artic regurgitatin Circulatin 1971;44: II. Firth BG, Dehmer GJ, Nicd P, Willersn JT, Hillis LD. Effect f increasing heart rate in patients with artic regurgitatin' effect f incremental atrial pacing n scintigraphic, hemdynamic and thermdilutin measurements. Am J Cardil 1982;49: Segal J, Harvey WP, Hufnagel C. A clinical study f 100 cases f severe artic insufficiency. Am J Med 1956,21: Spagnul M, Klth H, Taranta A, Dyle E, Pasternack B. Natural histry f rheumatic artic regurgitatin: criteria predictive f death, cngestive heart failure and angina in yung patients. Circulatin 1971;44: Gldschlager N, Pfeifer J, Chn K, Ppper R, Selzer A. Natural histry f artic regurgitatin: a clinical and hemdynamic study. Am J Med 1973;54: Bnw RD, Rsing DR, Kent KM, Epstein SE. Timing f peratin fr chrnic artic regurgitatin. Am J Cardil 1982:50: Berergard S, Hlmgren A, Jnssn B The effect f bdy psinn n circulatin at rest and during exercise with special reference t the influence n the strke vlume. Acta Physil Scand 1960;49: Thadani V, Parker J. Hemdynamics at rest and during supine and sitting bicycle exercise in nrmal subjects. Am J Cardl1 1978;41: Plmer LR, Dehmer GJ, Lewis SE, Parkey RW, Blmquist CG, Willersn JT. Left ventricular perfrmance In nrmal subjects: a cmparisn f the respnses t exercise 10 the upright and supine psitrns Circulatin 1980;62: Benjamin IJ, Schuster EH, Bulkley BH Cardiac hypertrphy in idipathic dilated cngestive cardimypathy. a clinicpathlgic study. Circulatin 1981;64: Feild BJ, Baxley WA, Russel RO, et al. Left ventricular functin and hypertrphy in cardimypathy with depressed ejectin fracnn. Circulatin 1973; Halle L, Orjavik 0, Strstein O. Chrnic mycardial disease. I. Clinical picture related t lng-term prgnsis. II. Hemdynamic findings related t lng-term prgnsis. Acta Med Scand 1976;199: Gaasch WH Left ventncular radius t wall thickness rati. Am J Cardil 1979;63: