Anaerobic metabolism in hypertensive patients during exercise stress test.

An impaired maximal vasodilating capacity has been reported in hypertensives. This study aimed to assess whether mild hypertensives depend on anaerobic metabolism more than do normal subjects during the exercise stress test. The oxygen uptake (VO2) and carbon dioxide output (VCO2) were measured at the anaerobic threshold (AT) and at peak exercise (VO2p and VCO2p) during the cardiopulmonary exercise test by breath-by-breath expiratory gas analysis in 21 mild hypertensives and 19 age-matched normotensives. AT was reached earlier in hypertensives than in normotensives, but with similar VO2 uptake, VCO2 output, and VCO2/VO2 ratio. At peak exercise, however, hypertensives showed lower VO2p than controls (29 +/- 5 v 33 +/- 5 mL VO2/kg/min, (P < .03) but similar VCO2p (36 +/- 6 v 39 +/- 6 mL VCO2/kg/min, P = .19). As a result, the slope of carbon dioxide output increase versus oxygen uptake after anaerobic threshold was steeper in hypertensives than in controls (P < .002). The higher CO2 production per unit of O2 in hypertensives as compared with controls seems to reflect a greater involvement of the anaerobic metabolism to supplement energy output.

Early impairment of the cardiopulmonary exercise capacity of hypertensive patients.

A reduction of functional capacity has been reported in severe hypertension. However, the reduced peripheral vasodilation observed in the early stages of hypertension, could also impair the blood supply to exercising muscles in mild hypertensives presenting a normal left ventricular mass. In this paper the cardiopulmonary exercise capacity of early hypertensives has been investigated. Thirty mild hypertensives (9 in stage I and 21 in stage II according to WHO) and 36 normotensives divided into two age and weight-matched groups, were investigated. All subjects underwent a stress test according to the modified Bruce protocol with contemporary assessment of breath-by-breath expiratory gas analysis and measurement of the anaerobic threshold (AT) and of the oxygen consumption at peak exercise (PVO2). Exercise duration and maximal workload, in stage I hypertensives, were similar to controls but the O2 consumption was significantly reduced in comparison to controls (P = 0.043). On the contrary, in stage II patients exercise duration, maximal workload, PVO2 and AT were significantly lower than in normotensives. No relationship between myocardial hypertrophy and ergometric or ventilatory (PVO2, AT, VE) parameters was found. In conclusion an early impairment of the aerobic exercise performance is detectable in uncomplicated (stage I WHO) mild hypertensives.

Automated blood pressure determination during exercise test. Clinical evaluation of a new automated device.

The accuracy and reproducibility of a new automatic device (P) specially designed for noninvasive blood pressure monitoring during the exercise stress test were evaluated in 50 consecutive subjects (34 normotensives and 16 hypertensives). Automatic measurements were compared with those taken by a sphygmomanometer (RR). A good agreement between systolic pressure values obtained by the two methods was found (RR 159 +/- 30 mmHg, P 158 +/- 28 mmHg, mean difference = -1.53 +/- 13 mmHg, p = 0.166, ns). On the contrary the new device significantly underestimated diastolic pressure values (RR 89.3 +/- 13 mmHg; P 84 +/- 13 mmHg, mean difference -5.37 +/- 9.3, p < 0.001). In conclusion the new device seems able to measure systolic but underestimates diastolic blood pressure both in hypertensives and in normotensives during the effort test.

[Changes in the wall motion of left ventricle in dipyridamole-induced ischemic cardiopathy studied by nuclear magnetic resonance. A comparison with myocardial scintigraphy with 99mTc MIBI]. / Alterazioni della motilità parietale del ventricolo sinistro nella cardiopatia ischemica indotte da dipiridamolo studiate con risonanza magnetica nucleare. Confronto con la scintigrafia miocardica mediante 99mTc MIBI.

To investigate whether magnetic resonance imaging (NMR) can detect alterations in LV contractility during myocardial ischemia, ten patients aged 32-72 with coronary artery disease underwent ECG gated NMR performed at 0.5 Tesla after intravenous infusion of high dose dipyridamole (DP) (0.7 mg/Kg) over 5 minutes. LV contraction in planes similar to echo short axis projection was imaged under condition, 3' and 15-20' after infusion of DP by fast multiphasic imaging (FMI), multiple angulated cine-NMR sequence with a temporal resolution of 50 m/sec. Entity and size of perfusion defects after DP were determined by Tc 99m MIBI myocardial scintigraphy. In all patients changes in LV contractility appeared at NMR in the same site of perfusion impairments revealed with MIBI. In 8 patients the alterations lasted even more than 20' after the first NMR scan. NMR provides the opportunity of performing long-lasting assessment of ventricular wall contractility and enables to exactly localize the site and extension of kinetic changes as well as their time of onset and time duration.

Anaerobic threshold in patients with exercise-induced myocardial ischemia.

The aim of the present study was to investigate the ventilatory anaerobic threshold in patients with exercise-induced myocardial ischemia. Ventilatory volumes and gas exchanges were measured during treadmill stress testing in 36 patients (11 with previous myocardial infarction) with electrocardiographic criteria of myocardial ischemia during the test and in 23 healthy, untrained control subjects of equivalent age. The anaerobic threshold was detected in 32 of 36 patients (89%) and in 22 of 23 control subjects (96%). The anaerobic threshold was significantly lower in patients than in control subjects (13.5 +/- 1.9 versus 19.7 +/- 1.7 ml/kg per minute VO2, p less than 0.001). In the 21 patients without previous myocardial infarction, the anaerobic threshold was also significantly lower than in the control subjects (13.9 +/- 1.6 versus 19.7 +/- 1.7 ml/kg per minute VO2, p less than 0.001). Among the 21 patients without previous myocardial infarction, the 12 with a low ischemic threshold, which occurred during the first three steps of the modified Bruce protocol, had an anaerobic threshold significantly lower than the other nine patients (13.1 +/- 1.5 versus 14.9 +/- 1.0 ml/kg per minute VO2, p less than 0.01). However, even in the patients with a moderate to high ischemic threshold, the anaerobic threshold was significantly lower than in the control subjects (p less than 0.001). These data show that the anaerobic threshold can be measured in the great majority of patients with exercise-induced myocardial ischemia. The low anaerobic threshold level indicates a relevant functional impairment in these patients.

[Changed diastolic function at rest in patients with perfusion defects in exertion myocardial scintigraphy with TI-201]. / Alterata funzione diastolica a riposo in pazienti con difetti di perfusione alla scintigrafia miocardica da sforzo con TI-201.

Myocardial perfusion scintigraphy with TI-201 after exercise allows distinction between areas of scar (irreversible defect) and areas of ischemia (reversible defects). Accordingly 4 major groups of patients can be identified: with normal perfusion pattern (Group I); with reversible ischemia (Group II); with scar of previous myocardial infarction (Group III); with both evidence of scar and ischemia (Group IV). Sixty-nine patients (59 m; 10 f; mean age 55.7 +/- 9 years) with suspected or demonstrated ischemic heart disease underwent stress TI-201 myocardial scintigraphy and on the basis of the scintigraphic results were assigned as follows: 11 to group 1, 14 to group II, 31 to group III and 13 to group IV. In order to investigate the behaviour of ventricular diastolic function in these different subsets, all the patients underwent subsequently a radionuclide angiography at rest (both first pass and equilibrium gated blood pool studies), which allowed the assessment of left ventricular ejection fraction (EF), peak filling rate (PFR)--as expression of diastolic function--and regional wall motion pattern. The values of EF and PFR were significantly reduced (p less than 0.05) in the patients with defects of perfusion (Groups II, III and IV) in comparison to the patients with normal perfusion (Group I); abnormal wall motion was found in 0 (I), 8 (II), 22 (III) and 7 (IV) patients. The diastolic function was more frequently altered (PFR less than 2.5 EDV/sec) than the systolic function (EF less than 50%) or regional wall motion, mainly in patients with reversible scintigraphic defects (prevalence of alterations in the groups II and IV: PFR: 78%, EF: 22%, abnormal wall motion: 56%).(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamics in borderline hypertension: acute effect of furosemide.

In order to identify the hemodynamics of borderline essential hypertension, radionuclide angiography was performed before and after bolus injection of furosemide (40 mg i.v.) both at 3 min (i.e. before diuretic effect) and at 30 min (i.e. after diuretic effect) in 16 borderline (B) patients and in 14 age-matched WHO classification I-II essential hypertensives (H) patients. 14 age-matched normotensive (N) subjects were used as controls. B patients were further subdivided into two subgroups according to a cardiac index under or above 3 liter/min/m2 in basal conditions. Baseline hemodynamic characteristics showed higher values of mean arterial pressure (MAP) and systemic vascular resistance index (SVRI) in both H and B patients when compared with N subjects (p less than 0.001). Furthermore, B and H patients exhibited lower values of left ventricular peak filling rate (PFR) than seen in N subjects (p less than 0.01 and p less than 0.05, respectively). H patients demonstrated higher peak systolic blood pressure/endsystolic volume ratio (PSP/ESV) than seen in N subjects (p less than 0.05). PFR positively correlated with peak emptying rate (PER) only in N and B patients (p less than 0.05). After furosemide administration, even though differences were observed in the absolute values, B and H patients showed similar hemodynamic patterns. Only the B subgroup with cardiac index (CI) greater than 3 liter ('volume-dependent' patients) showed a decrease in left ventricular end-diastolic volume index (LVEDVI) at 30 min associated with a lowering of stroke index (SI; p less than 0.005 for both), when compared with pre-drug values. In B patients with CI less than 3 liter ('afterload-dependent' patients) no differences were observed either at 3 min or at 30 min in comparison with values obtained prior to drug administration. Moreover, in this subgroup, like in H patients, there was a negative correlation (p less than 0.01) between 3-min percent change of SVRI and 3-min percent change of SI. Our data suggest that in 'borderline' hypertension: (a) there may be an increase in peripheral resistance, as in established hypertension, especially when age-matched groups are considered; (b) the earliest sign of compromised left ventricular function is the reduction in diastolic PFR but, unlike established hypertension, this index is still correlated with systolic function; (c) cardiac output might be even somewhat reduced and also negatively correlated with vascular resistance ('afterload-dependent' hearts); (d) furosemide (acute administration) might contribute to a better definition of hemodynamic behavior.

Short-term responses to cardiac rehabilitation after acute myocardial infarction. Cardiac function evaluation before and after physical training at rest and during stress test.

Whether physical training, soon after myocardial infarction (MI), has effects upon intrinsic cardiac function at rest and during exertion remains unresolved. We have evaluated ventricular function using radionuclide angiography at rest and during stress testing before and after 3 months' physical training. This has been correlated with the site of MI and with changes in the ST segment during the maximal exercise test performed before the postmyocardial infarction rehabilitation program. We have studied 27 patients, mean age 54 +/- 10 years, in NYHA class I or II. Twelve showed no changes in the ST segment during erogmetric stress test (group 1); seven showed ST segment depression greater than 1 mm in leads different from those of MI (group 2); eight showed ST segment elevation of 2 mm (group 3). Twelve patients had had anterior MI only (AMI group); twelve inferior MI only (IMI group). After rehabilitation, all patients showed an increased work capacity and a decreased double product at the same work load. In the total group, significant increases were found in the left ventricular ejection fraction (LVEF) and in the contractile regional performance (LVwm) at rest, as well as a lesser decrease in the LVEF during handgrip test. Group 1 showed a significant increase in LVEF, associated with a decrease in left ventricular end-diastolic volume (EDV) at rest. Group 2 showed unchanged variables after rehabilitation. Group 3 showed a better LVEF during handgrip with an increase of EDV at rest. The AMI group showed a better LVEF and LVwm at rest and a better LVEF during handgrip. IMI group showed a better right ventricular ejection fraction during handgrip without improvement in LVEF. No patient with IMI had septal asynergy. We conclude that the effects of rehabilitation were linked to the site of MI and to the functional dynamic status of both ventricles.

Haemodynamic effects of carbochromen.

Carbochromen increases coronary flow and cardiac output. A previous study has advanced the hypothesis that the latter may be due to afterload reduction. Fourteen patients with coronary heart disease have now been studied by means of radionuclide angiocardiography. Gated blood pool angiocardiographic data were collected in basal conditions and, without moving the patient, 80 mg of carbochromen were administered i.v. Data were collected again, following infusion, during 3'-6'(1) and 7'-10'(2) periods. Changes in the following parameters have been evaluated: LV ejection fraction (EF), LV ejection rate (ER), system pressure (BP), heart rate (HR), cardiac output index (CO), stroke volume index (SV), LV end-diastolic volume index (EDV), systemic vascular resistance index (SVR), regional LV wall motion. During period 1 a significant decrease was observed in BP and SVR, the other parameters remaining unchanged. During period 2 there was a significant increase in CO, SV, EF, ER and a significant decrease in SVR. BP was unchanged. No changes were ascertained in HR and EDV. Eight patients, in basal conditions, showed asynergy in the LAO projection. Three of these patients showed improved wall motion during period 2. A possible central action of carbochromen should be pointed out. This conclusion can be drawn by observing the increase in the pump indexes, while BP and SVR show a decrease and EDV and HR no change. The left ventricular wall motion improvement observed in some of the cases confirms the possibility that carbochromen is capable of improving cardiac contractility. This effect may follow the regional myocardial perfusion increase.

[Hemodynamic correlation of the systolic movement of the aortic root]. / Correlazioni emodinamiche del movimento sistolico della radice aortica.

Factors influencing the anterior systolic movement of the aortic posterior wall (PAM) are complex and still controversial. Left atrial events seem to be more important that stroke volume or left ventricular function in determining PAM. Even if the reduction of systolic aortic movement is generally associated to a severe impairment of left ventricular function, very few studies correlate the changes in the amplitude of aortic systolic movement to the hemodynamic pattern. In 50 patients posterior aortic wall echocardiograms, right heart catheterization and 99mTc angiocardiography were performed within 24 h. According to hemodynamic and left ventricular wall motion parameters 18 patients resulted to have a normal (1st group) and 32 patients (2nd group) an impaired left ventricular function. In the 2nd group mean values of PAM were significantly lower than in the 1st group (7.4 +/- 2.9 mm vs 10.2 +/- 1.9 mm). A significant correlation was found between PAM and hemodynamic parameters, i.e. CPW (r = 0.58), EF (r = 0.58) and SV (r = 0.40), whereas no significant correlations were found between these parameters and left atrial dimensions and between PAM and left atrial dimensions. A high significant correlation was found between PAM and echocardiographically measured septal wall motion (r = 0.80). All patients with PAM Less Than 6 mm and echo septal wall motion Less Than 5 mm had an akinesis or a dyskinesis of septal wall quantitatively determined with 99mTc angiocardiography. These findings suggest that one of the main determinants of PAM is left ventricular wall motion and in particular left ventricular septal motion.