Systolic time intervals in chronic hypertension: Alterations and response to treatment

Age- and sex-based normal reference ranges of the cardiac time intervals: the Copenhagen City Heart Study

BACKGROUND

Color tissue Doppler imaging (TDI) M-mode can be used to measure the cardiac time intervals including the isovolumic contraction time (IVCT), the left ventricular ejection time (LVET), the isovolumic relaxation time (IVRT), and the combination of all the cardiac time intervals in the myocardial performance index (MPI) defined as [(IVCT + IVRT)/LVET]. The aim of this study was to establish normal age- and sex-based reference ranges for the cardiac time intervals.

METHODS AND RESULTS

A total of 1969 participants free of cardiovascular diseases and risk factors from the general population with limited age range underwent an echocardiographic examination including TDI. The median age was 46 years (25th-75th percentile: 33-58 years), and 61.5% were females. In the entire study population, the IVCT was observed to be 40 ± 10 ms [95% prediction interval (PI) 20-59 ms], the LVET 292 ± 23 ms (95% PI 248-336 ms), the IVRT 96 ± 19 ms (95% PI 59-134 ms) and MPI 0.47 ± 0.09 (95% PI 0.29-0.65). All the cardiac time intervals differed significantly between females and males. With increasing age, the IVCT increased in females, but not in males. The LVET did not change with age in both sexes, while the IVRT increased in both sexes with increasing age. Furthermore, we developed regression equations relating the heart rate to the cardiac time intervals and age- and sex-based normal reference ranges corrected for heart rate.

CONCLUSION

In this study, we established normal age- and sex-based reference ranges for the cardiac time intervals. These normal reference ranges differed significantly with sex.

Changes in cardiac time intervals over a decade and the risk of incident heart failure: The Copenhagen City heart study

BACKGROUND

The cardiac time intervals include the isovolumic contraction time (IVCT), the left ventricular ejection time (LVET), the isovolumic relaxation time (IVRT) and the combination of all the cardiac time intervals in the myocardial performance index (MPI) (defined as [(IVCT+IVRT)/LVET)]. Whether the cardiac time intervals change over time and which clinical factors that accelerate these changes is not well-established. Additionally, whether these changes are associated with subsequent heart failure (HF), remains unknown.

METHODS

We investigated participants from the general population (n = 1064) who had an echocardiographic examination including color tissue Doppler imaging performed in both the 4th and 5th Copenhagen City Heart Study. The examinations were performed 10.5 years apart.

RESULTS

The IVCT, LVET, IVRT and MPI increased significantly over time. None of the investigated clinical factors were associated with increase in IVCT. Systolic blood pressure (standardized β= - 0.09) and male sex (standardized β= - 0.08) were associated with an accelerated decrease in LVET. Age (standardized β=0.26), male sex (standardized β=0.06), diastolic blood pressure (standardized β=0.08), and smoking (standardized β=0.08) were associated with an increase in IVRT, while HbA1c (standardized β= - 0.06) was associated with a decrease in IVRT. Increasing IVRT over a decade was associated with an increased risk of subsequent HF in participants aged <65 years (per 10 ms increase: HR 1.33; 95%CI (1.02-1.72), p = 0.034).

CONCLUSION

The cardiac time increased significantly over time. Several clinical factors accelerated these changes. An increase in IVRT was associated with an increased risk of subsequent HF in participants aged <65 years.

Ventricular Function and Cardio-Ankle Vascular Index in Patients With Pulmonary Artery Hypertension

Aim

This study aims to evaluate the left ventricle (LV) systolic and diastolic function in patients with idiopathic pulmonary arterial hypertension (IPAH) and its correlation with systemic arterial stiffness assessed by cardio-ankle vascular index (CAVI).

Patient and methods

We included 37 patients with IPAH and 20 healthy people matched by age. All patients were assessed: vital signs, 6-minute walk test, NT-proBNP level, the CAVI, the right ventricular (RV) and LV function parameters, including ejection time (ET), tissue speckle-tracking values - global longitudinal strain (GLS) and strain rate (SR).

Results

The groups were matched by age, gender, BMI, office SBP and DBP. Patients with IPAH had higher heart rate, NT-proBNP level and lower ferritin level, GFR (CKD-EPI), SaO₂ than healthy people. The mean CAVI_left was higher in IPAH patients than in the control group- 8.7±1.1 vs 7.5±0.9, P=0.007. Healthy people had significantly less E/e' and lower IVRT. LVET and RVET were shorter in IPAH patients. Patients with IPAH had mean LVGLS -(-17.6±4.8%) and 35.1% of them were with LVGLS ≤16% compared to healthy people -(-21.8±1.4%) and 0%, respectively. LVSR was significant less in IPAH patients, but in the normal range. We found significant correlations of CAVI with age, history of syncope, bilirubin, uric acid, total cholesterol, cardiac output, cardiac index, RVET, LVET and E/A. Multiple linear regression confirmed the independent significance for age (β=0.083±0.023, CI 0.033-0.133) and RVET (β=-0.018±0.005, CI -0.029 to -0.008) only. The risk to have CAVI ≥8 increased in 5.8 times in IPAH patients with RVET <248 ms (P=0.046). CAVI did not correlate with LVGLS and LVSR.

Conclusion

Significant worse systolic and diastolic LV functions were stated in pulmonary hypertensive patients compared to the control group. No LV GLS, no LV SR had significant associations with arterial stiffness evaluated by CAVI.

The significance of left ventricular ejection time in heart failure with reduced ejection fraction

Left ventricular ejection time (LVET) is defined as the time interval from aortic valve opening to aortic valve closure, and is the phase of systole during which the left ventricle ejects blood into the aorta. LVET has been used for several decades to assess left ventricular function and contractility. However, there is a recent interest in LVET as a measure of therapeutic action for novel drugs in patients with heart failure with reduced ejection fraction (HFrEF), since LVET is shortened in these patients. This review provides an overview of the available information on LVET including methods of measuring LVET, mechanistic understanding of LVET, association of LVET with outcomes, mechanisms behind shortened LVET in HFrEF and the potential implications of drugs that affect and normalize LVET.

Investigating the estimation of cardiac time intervals using gyrocardiography

OBJECTIVE

Assessment of cardiac time intervals (CTIs) is essential for monitoring cardiac performance. Recently, gyrocardiography (GCG) has been introduced as a non-invasive technology for cardiac monitoring. GCG measures the chest's angular precordial vibrations caused by myocardium wall motion using a gyroscope sensor attached to the sternum. In this study, we investigated the accuracy and reproducibility of estimating CTIs from the GCG recordings of 50 adults.

APPROACH

We proposed five fiducial points for the GCG waveforms associated with the opening and closure of aortic and mitral valves. Two annotators annotated the suggested points on each cardiac cycle. The points were compared to the corresponding opening and closing of cardiac valves delineated on Tissue Doppler imaging (TDI) recordings. The fiducial points were annotated on seismocardiography (SCG) and impedance cardiography (ICG) signals recorded simultaneously.

MAIN RESULTS

For estimating the timing of mitral valve closure, aortic valve opening, aortic valve closure, and mitral valve opening, 40%, 67%, 75%, and 70% of GCG annotations fell in the corresponding echocardiography ranges, respectively. The results showed moderate-to-excellent (r = 0.4-0.92; p-value < 0.01) correlation between the measured and the reference CTls. A myocardial performance index (Tei index) adapted using joint GCG and SCG resulted in a moderate correlation (r = 0.4; p-value < 0.001).

SIGNIFICANCE

The findings showed that the CTIs can be easily measured using GCG. Also, we found that using SCG and GCG recordings together could provide an opportunity to estimate CTIs more accurately, and make it possible to calculate the Tei index as an indicator of myocardial performance.

Left ventricular ejection time is an independent predictor of incident heart failure in a community-based cohort

AIMS

Systolic time intervals change in the progress of cardiac dysfunction. The usefulness of left ventricular ejection time (LVET) to predict cardiovascular morbidity, however, is unknown.

METHODS AND RESULTS

We studied middle-aged African-Americans from one of four cohorts of the Atherosclerosis Risk in Communities study (Jackson cohort, n=1980) who underwent echocardiography between 1993 and 1995. Left ventricular ejection time was measured by pulsed-wave Doppler of the left ventricular outflow tract and related to outcomes. A shorter LVET was associated with younger age, male sex, higher diastolic blood pressure, higher proportion of diabetes, higher heart rate, higher blood glucose levels and worse fractional shortening. During a median follow-up of 17.6 years, 384 (19%) had incident heart failure (HF), 158 (8%) had a myocardial infarction, and 587 (30%) died. In univariable analysis, a lower LVET was significantly associated with increased risk of all events (P<0.05 for all). However, after multivariable adjustment for age, sex, hypertension, diabetes, body mass index, heart rate, systolic and diastolic blood pressure, fractional shortening and left atrial diameter, LVET remained an independent predictor only of incident HF [hazard ratio 1.07 (1.02-1.14), P=0.010 per 10 ms decrease]. In addition, LVET provided incremental prognostic information to the known risk factors included in the Framingham risk score, in regard to predicting all outcomes except for myocardial infarction.

CONCLUSION

Left ventricular ejection time is an independent predictor of incident HF in a community-based cohort and provides incremental prognostic information on the risk of future HF and death when added to known risk prediction models.

Renal systolic time intervals derived from intra-renal artery Doppler as a novel predictor of adverse cardiac outcomes

The aim of this study was to evaluate the use of renal systolic time intervals measured by electrocardiographic gated Doppler ultrasonography for predicting adverse cardiac events. This longitudinal observation study enrolled 205 patients. Renal systolic time intervals, including pre-ejection period (PEP) and ejection time (ET), and ratio of renal PEP to ET, were measured by electrocardiographic gated Doppler ultrasound. The 14 adverse cardiac events identified in this population included 9 cardiac deaths and 5 hospitalizations for heart failure during an average follow up of 30.9 months (25^th-75^th percentile: 30-33 months). Renal PEP (hazard ratio = 1.023, P = 0.001), renal ET (hazard ratio = 0.975, P = 0.001) and renal PEP/ET (per 0.01 unit increase, hazard ratio = 1.060, P < 0.001) were associated with poor cardiac outcomes. The addition of renal PEP/ET to a Cox model containing important clinical variables and renal resistive index further improved the value in predicting adverse cardiac events (Chi-square increase, 9.996; P = 0.002). This study showed that parameters of intra-renal hemodynamics were potential predictors of adverse cardiac outcomes. However, the generalizability of these indicators need to be investigated in future large-scale studies.

Impaired left ventricular function in the presence of preserved ejection in chronic hypertensive conscious pigs

Systolic function is often evaluated by measuring ejection fraction and its preservation is often assimilated with the lack of impairment of systolic left ventricular (LV) function. Considering the left ventricle as a muscular pump, we explored LV function during chronic hypertension independently of increased afterload conditions. Fourteen conscious and chronically instrumented pigs received continuous infusion of either angiotensin II (n = 8) or saline (n = 6) during 28 days. Hemodynamic recordings were regularly performed in the presence and 1 h after stopping angiotensin II infusion to evaluate intrinsic LV function. Throughout the protocol, the mean arterial pressure steadily increased by 55 ± 4 mmHg in angiotensin II-treated animals. There were no significant changes in stroke volume, LV fractional shortening or LV wall thickening, indicating the lack of alterations in LV ejection. In contrast, we observed maladaptive changes with (1) the lack of reduction in isovolumic contraction and relaxation durations with heart rate increases, (2) abnormally blunted isovolumic contraction and relaxation responses to dobutamine and (3) a linear correlation between isovolumic contraction and relaxation durations. None of these changes were observed in saline-infused animals. In conclusion, we provide evidence of impaired LV function with concomitant isovolumic contraction and relaxation abnormalities during chronic hypertension while ejection remains preserved and no sign of heart failure is present. The evaluation under unloaded conditions shows intrinsic LV abnormalities.

Central versus peripheral cardiovascular risk in metabolic syndrome

Individuals with metabolic syndrome (MetS; i.e., three of five of the following risk factors (RFs): elevated blood pressure, waist circumference, triglycerides, blood glucose, or reduced HDL) are thought to be prone to serious cardiovascular disease and there is debate as to whether the disease begins in the peripheral vasculature or centrally. This study investigates hemodynamics, cardiac function/morphology, and mechanical properties of the central (heart, carotid artery) or peripheral [total peripheral resistance (TPR), forearm vascular bed] vasculature in individuals without (1–2 RFs: n = 28), or with (≥3 RFs: n = 46) MetS. After adjustments for statin and blood pressure medication use, those with MetS had lower mitral valve E/A ratios (<3 RFs: 1.24 ± 0.07; ≥3 RFs: 1.01 ± 0.04; P = 0.025), and higher TPR index (<3 RFs: 48 ± 2 mmHg/L/min/m²; ≥3 RFs: 53 ± 2 mmHg/L/min/m²; P = 0.04). There were no differences in heart size, carotid artery measurements, cardiovagal baroreflex, pulse-wave velocity, stroke volume index, or cardiac output index due to MetS after adjustments for statin and blood pressure medication use. The use of statins was associated with increased inertia in the brachial vascular bed, increased HbA1c and decreased LDL cholesterol. The independent use of anti-hypertensive medication was associated with decreased predicted VO2max, triglycerides, diastolic blood pressure, interventricular septum thickness, calculated left ventricle mass, left ventricle posterior wall thickness, and left ventricle pre-ejection period, but increased carotid stiffness, HDL cholesterol, and heart rate. These data imply that both a central cardiac effect and a peripheral effect of vascular resistance are expressed in MetS. These data also indicate that variance in between-group responses due to pharmacological treatments are important factors to consider in studying cardiovascular changes in these individuals.

Systolic time intervals as simple echocardiographic parameters of left ventricular systolic performance: correlation with ejection fraction and longitudinal two-dimensional strain

AIMS

Conventionally, the evaluation of left ventricular (LV) systolic function is based on ejection fraction assessment, which may be supplemented by other echocardiographic techniques, such as tissue Doppler imaging, 3D evaluation, and speckle tracking strains. However, these imaging modalities have a high technicity and are time-consuming, while being associated with reproducibility limitations. In this context, the usefulness of simpler measurements such as systolic time intervals (STI) by pulsed Doppler echocardiography must be emphasized.

METHODS AND RESULTS

In this multicentre study, left ventricular ejection fraction (LVEF), dP/dt(max), LV stroke volume, myocardial longitudinal deformation, aortic pre-ejectional period (PEP, ms), and left ventricular ejection time (LVET, ms) were prospectively investigated and compared in 134 consecutive heart failure (HF) patients and 43 control subjects. Feasibility of STI measurements was 100%. Intra-observer reproducibility was 98% for PEP, 96% for LVET, 87% for LVEF, and 93% for global longitudinal strain (GLS). By subgroup analyses, with increasingly altered LVEF or GLS, PEP significantly increased, whereas significantly LVET decreased, resulting in a significantly increased PEP/LVET ratio (P < 0.001). In the HF patients group, a correlation between LVEF and PEP/LVET was found, with r = 0.55 (y = -0.0083x + 0.75, P < 0.001). Based on receiver operating curve analyses, the area under the curve was 0.91 for PEP/LVET > 0.43, which allowed us to detect LVEF < 35% with a sensitivity of 87%, and a specificity of 84%.

CONCLUSION

STI can be easily and accurately measured in clinical practice, and may be used for detecting alterations in LV systolic function. Moreover, this method is likely to have potential applications in the management of HF patients.

Mechanism of prolongation of pre-ejection period in the hypertrophied left ventricle with normal systolic function in unanesthetized hypertensive dogs

To determine the mechanism for prolongation of pre-ejection period (PEP) in the hypertensive heart with normal systolic function, cardiac catheterizations, echocardiograms, and electrocardiograms were performed at the baseline period (CS, control stage) and eight weeks (HS, hypertensive stage) after the induction of systemic hypertension by Page's method in unanesthetized dogs. Mean aortic blood pressure increased significantly (96 +/- 12 to 137 +/- 26 mmHg) (p less than 0.05). Diastolic aortic pressure also increased significantly (80 +/- 12 to 118 +/- 24 mmHg) (p less than 0.01). Left ventricular (LV) PEP of HS was significantly prolonged (72 +/- 12 vs. 87 +/- 22 ms, CS vs. HS). The ratio of LV pre-ejection period to ejection time (PEP/ET) also increased significantly (0.33 +/- 0.04 to 0.42 +/- 0.07) (p less than 0.05). LV end-diastolic wall stress as an index of preload decreased significantly (7.7 +/- 2.5 vs. 5.9 +/- 1.8 10(3) dynes/cm2, CS vs. HS). Heart rate, mean velocity of circumferential fiber shortening (VCF) and end-systolic wall stress of HS did not change. That is, myocardial contractility in the hypertensive heart of HS most likely is not depressed. At autopsy, left ventricle to body weight ratio of HS was significantly (p less than 0.01) greater than the sham-operated dogs (5.7 +/- 0.8 vs. 4.3 +/- 0.5 g/kg). From these findings, there are two possible factors responsible for prolongation of PEP of HS. First, elevated diastolic aortic pressure may influence PEP. Second, the prolonged PEP is possibly caused by the decrease of preload.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between systolic time intervals and arterial blood pressure

It has been suggested that systolic time intervals (STI) can be used to monitor the cardiac effects of antihypertensive treatments and also to evaluate hypertensive patients. STI changes observed in hypertensives have been ascribed to myocardial disease, although they could be due to the existence of a relationship between STI and blood pressure. A group of 37 subjects (18 normotensives and 19 hypertensives) with no signs of heart failure and left ventricular dysfunction were studied to examine the relationship of STI to blood pressure. Pacing with an external battery pulse generator was performed at the rate of 95 beats/min in order to eliminate differences in heart rate. STI were measured from good quality high speed (100 mm/s) recordings and the average value of 10 consecutive cardiac cycles was used for statistical analysis. Normal subjects showed significantly lower values of pre-ejection period (PEP), electromechanical systole (QS2), and pre-ejection period/left ventricular ejection time ratio (PEP/LVET). Moreover, a significant inverse relationship between diastolic pressure and LVET and significant direct relationships between diastolic pressure and PEP, systolic pressure and PEP, diastolic pressure and PEP/LVET, and between systolic pressure and PEP/LVET were demonstrated. We suggest to consider the relation of STI to blood pressure to provide regression equations to best appreciate and use STI.

Left ventricular mass and systolic performance in chronic systemic hypertension

This study was undertaken to define the relation between the extent of left ventricular (LV) hypertrophy and ventricular systolic performance in patients with chronic systemic hypertension. Ninety patients with chronic systemic hypertension were compared with 41 normal subjects as determined by angiography. LV mass was estimated from the M-mode echocardiogram. Patients were separated into 3 groups: those with LV mass of less than 2 (group I, n = 58), 2 to 4 (group II, n = 21) and more than 4 (group III, n = 11) standard deviations above mean normal. The ratio of preejection period to LV ejection time (PEP/LVET), percent shortening of the echocardiographic internal diameter (% delta D) and velocity of circumferential shortening (Vcf) were used as indexes of LV systolic performance. The frequency of abnormality, expressed as percent of patients in groups I, II and III, was 33%, 55% and 85% for PEP/LVET, 15%, 35% and 72% for % delta D, and 0%, 15% and 55% for Vcf. For each group PEP/LVET was the most frequently abnormal measure and Vcf was the least frequent abnormality. Calculation of peak and end-systolic wall stress was used as an index of the adequacy of LV hypertrophy. This index was significantly reduced in group I, did not differ from control in group II and was significantly increased in group III, indicating that hypertrophy was appropriate to wall tension in groups I and II. It is concluded that the occurrence of LV dysfunction with increasing LV mass in patients with moderate LV hypertrophy (group I and II) reflects a deficiency in intrinsic contractile performance of the hypertrophied myocardium.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiovascular effects of ketanserin, a new antiserotonergic agent in the treatment of arterial hypertension

Ketanserin, an investigational, antiserotonergic agent, at a dose of 40 mg bid was given to 18 patients with mild to moderate primary hypertension in a randomized, double-blind, crossover study, with 100-mg metoprolol bid for four weeks each. The following parameters were evaluated: blood pressure, heart rate, cardiac workload (product of systolic blood pressure and heart rate during bicycle exercise), systolic time intervals, and peripheral blood flow (by strain-gauge plethysmography). Significant reductions in diastolic and concomitant slight decreases in systolic blood pressure without changes in heart rate were observed during ketanserin treatment; cardiac oxygen demands during exercise test did not change, however. Pre-ejection period and left ventricular ejection time were unchanged, while significant increase in rest flow to the lower limbs and decrease in peripheral resistance were demonstrated by strain-gauge plethysmography. The results indicate that ketanserin has vasodilating properties and hypotensive activity that may be useful in the management of patients with essential hypertension.

Cardiovascular effects of intramuscular or inhaled terbutaline in asthmatics

8 stable asthmatics were at random given placebo, 0.125 mg, 0.25 mg, 0.5 mg and 1 mg terbutaline intramuscularly or 2.5 mg as inhalation. Systolic time intervals, echocardiographic parameters and peak expiratory flow (PEF) were measured. Maximal circulatory and respiratory response was obtained after 0.5 mg and 0.25 mg, respectively. The circulatory effect of 2.5 mg inhaled terbutaline equalled 0.125 mg given intramuscularly, while this dosage elicited maximal bronchodilator effect. Thus, nebulized terbutaline has only a minimal circulatory effect, and even the intramuscular dosages were without dramatic circulatory side effects.

Non-invasive measuring of the circulatory effect of afterload reduction in order to monitor the pharmacodynamic effect of drugs in normal volunteers

In order to measure the effect of a decrease in afterload on systolic time intervals, left ventricular end-systolic diameter, and left ventricular wall stress, eight healthy young persons underwent a randomised placebo controlled trial of terbutaline before and during atenolol treatment. Pre-ejection period index, left ventricular end-systolic diameter, and wall stress all decreased after terbutaline, the decrease being clearly dose dependent. This was identical before and during atenolol administration. Consequently the observed changes were induced by beta-2 elicited vasodilatation, possibly combined with some decrease of parasympathetic tone. A close correlation between changes in pre-ejection period index (PEPI) and changes in left ventricular end-systolic diameter (LVESD) and wall stress was shown both before and during atenolol treatment. When using non-invasive methods in the evaluation of changes in contractility, it is important to correct for changes in preload and afterload. For normal subjects it is suggested that the relation between delta PEPI and delta LVESD as a percentage of the mean values should be used for evaluation of afterload changes. A method is suggested for estimating changes in pre-ejection period index induced by changes in left ventricular end-systolic diameter or wall stress.

Pindolol and systolic time intervals in patients with hypertension

Two studies of systolic time intervals (STIs) in patients with mild to moderate hypertension (HBP) revealed that no mean change in systolic intervals occurred with pindolol therapy, although some patients had significant alterations in their STIs. Pindolol responders with normal pretreatment preejection period to left ventricular ejection time (PEP/LVET) ratios had a significant increase in this ratio following pindolol therapy, whereas those with abnormal pretreatment PEP/LVET ratios had improvement in this ratio on administration of the drug. Patients on propranolol showed no change in PEP/LVET ratio. Propranolol administration slowed heart rate and lengthened Q-S2, S1-S2, and LVET, however, without altering the Q-S2 and LVET index, indicating that the changes were caused by the effect of propranolol on the heart rate alone. Chlorthalidone in high doses significantly reduced the Q-S2 index and the S1-S2 index, indicating that these changes were not caused by alteration of the heart rate. The second study suggests that STIs may provide a predictive clue for clinical response to pindolol. Patients with normal cardiac function (group I) are more likely to respond to pindolol than are those with abnormal cardiac function (group II). Directionally opposite changes in STIs in the two subgroups suggest different mechanisms for changing cardiac function. Pindolol's dual role as a beta-blocking agent with intrinsic sympathomimetic activity is proposed as a possible explanation, beta-blocking effects predominating in group I and sympathomimetic activity balancing the beta effect in group II.

Left ventricular performance in patients with left ventricular hypertrophy caused by systemic arterial hypertension

To assess the adaptation of the left ventricle to a chronic pressure overload we used echocardiography to study 18 patients with left ventricular hypertrophy caused by systemic arterial hypertension. Increased values for either posterior wall or interventricular septal thickness or both confirmed the presence of left ventricular hypertrophy in all patients and an increase in the average wall thickness to radius ratio was consistent with the development of concentric hypertrophy. No patient had clinical evidence of ischaemic heart disease. Ejection phase indices of left ventricular performance (mean Vcf, fractional per cent of shortening, normalised posterior wall velocity, and ejection fraction) were within the normal range in the basal state in 16 of the 18 patients. The hypothesis is advanced that patients with concentric left ventricular hypertrophy resulting from systemic arterial hypertension usually have normal left ventricular performance in the basal state because values for wall stress remain within the normal range. We conclude that the hypertrophic response to a chronic increase in systemic arterial pressure does not per se result in depression of the basal inotropic state of the left ventricle.