Hemodynamic, humoral and volume findings in systemic hypertension with isolated ventricular septal hypertrophy

Effect of erythropoietin on cardiovascular prognosis parameters in hemodialysis patients

BACKGROUND

Renal anemia is an important determinant for left ventricular hypertrophy in dialysis patients and an independent prognosis parameter for the cardiovascular survival in dialysis patients. In addition, an autonomic dysfunction is associated with the uremic state and influences the cardiovascular risk in patients with end-stage renal disease (ESRD).

METHODS

We investigated in this prospective longitudinal study the effect of hemoglobin normalization by a chronic treatment with recombinant human erythropoietin (rhEPO) on cardiovascular prognosis parameters in 23 patients on chronic hemodialysis with renal anemia (hemoglobin concentration < or =10.5 g/dL) and echocardiographically proven left ventricular hypertrophy. We studied muscle sympathetic nerve activity measured by microneurography; cardiopulmonary baroreflex activity by lower-body negative pressure (LBNP-) testing; left ventricular structure and mass index (LVMI) by echocardiography; blood pressure by 24-hour readings; peripheral blood flow and vascular resistance by plethysmography before (U1) and after 7 months of chronic rhEPO treatment (U2).

RESULTS

In the anemic state, mean (+/- SD) muscle sympathetic nerve activity in ESRD was elevated (U1 rest, 34 +/- 13 bursts per minute) and cardiopulmonary baroreflex response during LBNP markedly lacking (U1 -15 mm Hg, 34 +/- 13 bursts per minute) reflecting a severely impaired autonomic function. Normalization of the hemoglobin concentration by chronic rhEPO treatment (U1, 10.5 +/- 0.9 g/dL versus U2, 13.4 +/- 3.1 g/dL, P <0.001) did not influence sympathetic nerve activity (U2, 34 +/- 15 bursts per minute, NS) and cardiopulmonary baroreflex sensitivity did not change (U2 -15 mm Hg, 37 +/- 16 bursts per minute, NS). LVMI decreased significantly after chronic treatment with rhEPO (U1, 134 +/- 26 g/m2 versus U2, 97 +/- 25 g/m2, P < 0.001) and left ventricular geometry developed from an asymmetric to a symmetric configuration (U1, relative wall thickness 0.58 versus U2, 0.43, P < 0.001). Under treatment with rhEPO, 24-hour systolic and diastolic blood pressure did not increase (systolic U1, 132 +/- 4 mm Hg versus U2, 128 +/- 3 mm Hg, NS, and diastolic U1, 76 +/- 2 mm Hg versus U2, 73 +/- 2 mm Hg, NS). Peripheral blood flow (U1, 6.1 +/- 3.3 mL/100 mL/min versus U2, 6.2 +/- 0.6 mL/100 mL/min, NS) as well as forearm vascular resistance (U1, 15.7 +/- 3.3 mm Hg/mL/100 mL versus U2, 14.9 +/- 3.1 mm Hg/mL/100 mL, NS) did not change by chronic rhEPO treatment.

CONCLUSION

Normalization of hemoglobin by chronic rhEPO treatment in dialysis patients has beneficial cardiovascular effects with regression of left ventricular hypertrophy and improvement of left ventricular geometry. However, a reduction of sympathetic overactivity or a resetting of baroreceptor sensitivity by a rhEPO treatment in dialysis patients in the medium-term could not be demonstrated. The reason for this may be the complex and multifactorial pathomechanism of autonomic dysfunction and cardiovascular disease in ESRD.

Impairment of vascular endothelial function and left ventricular filling : association with the severity of apnea-induced hypoxemia during sleep

STUDY OBJECTIVE

To investigate whether a dose-effect relationship exists between the severity of obstructive sleep apnea (OSA) and subclinical indicators of myocardial or vascular dysfunction.

DESIGN

Cross-sectional study using correlation analysis.

PARTICIPANTS

Twenty subjects referred to our sleep laboratory for screening or therapy of OSA but without regular medication and without known cardiovascular disease.

MEASUREMENTS

Severity of OSA was quantified by polysomnography. Moreover, nocturnal excretion of norepinephrine was determined. Left ventricular (LV) myocardial function was assessed with Doppler echocardiography. Using ultrasonographic measurements, endothelium-dependent and endothelium-independent conduit artery dilation were measured as flow-mediated and glyceryltrinitrate-induced changes in brachial artery diameter.

RESULTS

Worsening nocturnal hypoxemia, measured as nocturnal oxygen saturation nadir or percentage of sleep time spent in hypoxemia (< 90% hemoglobin oxygen saturation), predicted increased interventricular septum thickness (corrected for age and body mass index), prolonged isovolumetric relaxation time, decreased ratio between peak early and late mitral flow velocities, as well as reduced endothelium-dependent dilatory capacity of the brachial artery (all relationships corrected for cofactor age and with p < 0.05) were observed. Associations between these cardiovascular function markers and nocturnal excretion of norepinephrine followed the same trend, but relations with interventricular septum thickness and flow-mediated artery dilation missed significance (p = 0.064 and p = 0.061, respectively). LV posterior wall thickness, measures of LV systolic function, early mitral flow deceleration time, and endothelium-independent artery dilation were not significantly related to the degree of nocturnal hypoxemia or norepinephrine excretion. None of the correlations with apnea-hypopnea index were statistically significant.

CONCLUSIONS

The severity of apnea-related hypoxemia is associated with a gradual deterioration of LV diastolic function as well as large-artery endothelial function.

Ventricular tachyarrhythmias, myocardial ischemia, and sudden cardiac death in patients with hypertensive heart disease

Hypertensive heart disease is increasingly considered to be a strong and independent risk factor for sudden cardiac death. Ventricular tachyarrhythmias in these patients are common and mainly the result of electrophysiologic abnormalities and increased electrical vulnerability of the hypertrophic myocardium. However, proarrhythmia in the hypertrophic heart often is facilitated and aggravated by electrolyte disturbances, the sympathoadrenergic tone, transient blood pressure crisis, and especially by the occurrence of myocardial ischemia. Myocardial ischemia in the setting of hypertensive heart disease may result from stenotic lesions in large and/or small coronary artery vessels and, in the absence of both, will result from the altered cellular oxygen supply and consumption in the hypertrophic myocardium. Recent studies have shown that acute and transient myocardial ischemia are common in many hypertensives, often fail to be symptomatic, and that the dynamic interaction of left ventricular hypertrophy, transient myocardial ischemia, and ventricular tachyarrhythmias may provide a crucial link for the high incidence of sudden cardiac death in patients with hypertensive heart disease.

Comparison of diastolic left ventricular filling and cardiac dysrhythmias in hypertensive patients with and without isolated septal hypertrophy

Although many patients with hypertension develop isolated septal hypertrophy (ISH) rather than concentric or eccentric left ventricular (LV) hypertrophy, limited data are available on cardiac structure, function, and arrhythmias in hypertensive patients with ISH. Clinical features, hemodynamics, M-mode echocardiograms, and 24-hour electrocardiographic recordings were evaluated in 21 healthy normotensive subjects, 23 hypertensive patients without LV hypertrophy, 31 hypertensive patients with concentric LV hypertrophy, and 23 hypertensive patients with ISH to determine the prevalence and complexity of cardiac arrhythmias and diastolic LV filling abnormalities. Age, sex, race, obesity indexes, preload, ejection fraction, and LV contractility were similar in all 4 groups, and arterial pressure and afterload were statistically similar in the 3 hypertensive groups. Left atrial emptying index (p < 0.01) and peak LV filling rate (p < 0.01), 2 indexes of diastolic LV filling, were significantly reduced in the 3 hypertensive groups compared with the normotensive group. The duration of rapid LV filling, however, was significantly prolonged only in hypertensive patients with concentric LV hypertrophy and ISH (p < 0.05) but not in hypertensive patients without LV hypertrophy. The prevalence (p < 0.001) and complexity (p < 0.001) of ventricular ectopic activity was also significantly increased to a similar degree in hypertensive patients with concentric LV hypertrophy and in those with ISH compared with normotensive subjects or hypertensive patients without LV hypertrophy. The prevalence and complexity of atrial ectopic activity was only increased significantly (p < 0.001) in those with ISH.

Hemodynamic differences between black patients and white patients with essential hypertension. State of the art lecture

Physiological studies reported from our laboratory over the past several years have been reviewed and support epidemiological reports indicating that hypertensive cardiac and vascular disease runs a more severe course in the black patient. Although comparison of systemic hemodynamics failed to demonstrate that, for any level of arterial pressure, the magnitude of total peripheral resistance (which is the hemodynamic hallmark of hypertensive disease) differed between black patients and white patients, there are more subtle differences that were ascertained. Thus, although intravascular (plasma) volume contracts as arterial pressure and total peripheral resistance increase in both racial groups, this relation may differ quantitatively. At least in some black patients (43%), intravascular volume may be more expanded; in these patients, this relation is less closely correlated with the renopressor system (i.e., plasma renin activity). Moreover, these studies indicated that, at any level of arterial pressure, cardiac (left ventricular mass and posterior wall thickness) and renal hemodynamic involvement is more severe in the black patient. These findings point to important differences that operate in black patients and white patients with essential hypertension. With further study, these findings may be translated into more specific antihypertensive therapeutic implications for patients of both racial groups with essential hypertension.

Cardiac structure and function in continuous ambulatory peritoneal dialysis: influence of blood purification and hypercirculation

Continuous ambulatory peritoneal dialysis (CAPD) is associated with obvious hemodynamic and blood purification advantages over intermittent hemodialysis. To determine whether this is reflected in favorable left ventricular (LV) structure and function, a group of 55 normotensive patients (aged 58.4 +/- 11.0 years) undergoing CAPD was analyzed by means of echocardiography. Characteristic findings were LV hypertrophy (158 +/- 50 gm/m2), mainly the result of septal thickening (13.3 +/- 2.8 mm), and left atrial dilatation (40.9 +/- 7.4 mm). Mean LV diameter in end diastole and end systole and posterior wall thickness were normal. Parameters of LV systolic function (ejection fraction [EF]: 62.0 +/- 13.0%; velocity of circumferential fiber shortening [Vcf]: 1.58 +/- 0.46 circ/sec) were in the upper normal range at a hyperdynamic circulatory state (cardiac index [CI] 4.67 +/- 1.82 L/min/m2. The amount of LV hypertrophy was related to the amount of hypercirculation (CI: p less than 0.001; hemoglobin: p less than 0.025) and quality of blood purification (creatinine, urea: p less than 0.02) but not to blood pressure, age, or duration of dialysis. Left atrial dilatation was inversely related to LV systolic function (EF, Vcf: p less than 0.001) and directly related to LV muscle mass (p less than 0.02). A low prevalence (13%) of pericardial effusion was independent of blood purification. We conclude that in normotensive patients receiving CAPD, a high prevalence of left atrial dilatation and asymmetric septal hypertrophy is found, the latter being related both to the amount of hypercirculation and the quality of blood purification.