Blood pressure and endocrine responses to changes in dietary sodium intake in cardiac transplant recipients. Implications for the control of sodium balance

Seven-Day Salt Loading Impairs Microvascular Endothelium-Dependent Vasodilation without Changes in Blood Pressure, Body Composition and Fluid Status in Healthy Young Humans

OBJECTIVES

We aimed to assess whether a 7-day high-salt (HS) diet affects endothelium-dependent and/or endothelium-independent microvascular function in the absence of changes in arterial blood pressure (BP), and to determine whether such microvascular changes are associated with changes in body composition and fluid status in healthy young humans.

MATERIALS AND METHODS

Fifty-three young healthy individuals (28 women and 25 men) were assigned to a 7-day low-salt diet (<3.5 g salt/day) followed by a 7-day HS diet (∼14 g salt/day). Skin microvascular blood flow in response to iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP) was assessed by laser Doppler flowmetry, and BP, heart rate (HR), plasma renin activity (PRA), serum aldosterone, serum and 24 h-urine sodium, potassium, urea and creatinine levels, together with body composition and fluid status measurement with a 4-terminal portable impedance analyzer were measured before and after diet protocols.

RESULTS

BP, HR, body composition and fluid status were unchanged, and PRA and serum aldosterone level were significantly suppressed after HS diet. ACh-induced dilation (AChID) was significantly impaired, while SNP-induced dilation was not affected by HS diet. Impaired AChID and increased salt intake, as well as impaired AChID and suppressed renin-angiotensin system were significantly positively correlated. Changes in body composition and fluid status parameters were not associated with impaired AChID.

CONCLUSION

7-day HS diet impairs microvascular reactivity by affecting its endothelium-dependent vasodilation in young healthy individuals. Changes are independent of BP, body composition changes or fluid retention, but are the consequences of the unique effect of HS on endothelial function.

Effect of longer-term modest salt reduction on blood pressure

BACKGROUND

A reduction in salt intake lowers blood pressure (BP) and, thereby, reduces cardiovascular risk. A recent meta-analysis by Graudal implied that salt reduction had adverse effects on hormones and lipids which might mitigate any benefit that occurs with BP reduction. However, Graudal's meta-analysis included a large number of very short-term trials with a large change in salt intake, and such studies are irrelevant to the public health recommendations for a longer-term modest reduction in salt intake. We have updated our Cochrane meta-analysis.

OBJECTIVES

To assess (1) the effect of a longer-term modest reduction in salt intake (i.e. of public health relevance) on BP and whether there was a dose-response relationship; (2) the effect on BP by sex and ethnic group; (3) the effect on plasma renin activity, aldosterone, noradrenaline, adrenaline, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides.

SEARCH METHODS

We searched MEDLINE, EMBASE, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles.

SELECTION CRITERIA

We included randomised trials with a modest reduction in salt intake and duration of at least 4 weeks.

DATA COLLECTION AND ANALYSIS

Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regression were performed.

MAIN RESULTS

Thirty-four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt vs usual salt) was -75 mmol/24-h (equivalent to a reduction of 4.4 g/d salt), the mean change in BP was -4.18 mmHg (95% CI: -5.18 to -3.18, I (2)=75%) for systolic and -2.06 mmHg (95% CI: -2.67 to -1.45, I (2)=68%) for diastolic BP. Meta-regression showed that age, ethnic group, BP status (hypertensive or normotensive) and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic BP of 5.8 mmHg (95%CI: 2.5 to 9.2, P=0.001) after adjusting for age, ethnic group and BP status. For diastolic BP, age, ethnic group, BP status and the change in 24-h urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that, in hypertensives, the mean effect was -5.39 mmHg (95% CI: -6.62 to -4.15, I (2)=61%) for systolic and -2.82 mmHg (95% CI: -3.54 to -2.11, I (2)=52%) for diastolic BP. In normotensives, the mean effect was -2.42 mmHg (95% CI: -3.56 to -1.29, I (2)=66%) for systolic and -1.00 mmHg (95% CI: -1.85 to -0.15, I (2)=66%) for diastolic BP. Further subgroup analysis showed that the decrease in systolic BP was significant in both whites and blacks, men and women. Meta-analysis of hormone and lipid data showed that the mean effect was 0.26 ng/ml/hr (95% CI: 0.17 to 0.36, I (2)=70%) for plasma renin activity, 73.20 pmol/l (95% CI: 44.92 to 101.48, I (2)=62%) for aldosterone, 31.67 pg/ml (95% CI: 6.57 to 56.77, I (2)=5%) for noradrenaline, 6.70 pg/ml (95% CI: -0.25 to 13.64, I (2)=12%) for adrenaline, 0.05 mmol/l (95% CI: -0.02 to 0.11, I (2)=0%) for cholesterol, 0.05 mmol/l (95% CI: -0.01 to 0.12, I (2)=0%) for LDL, -0.02 mmol/l (95% CI: -0.06 to 0.01, I (2)=16%) for HDL, and 0.04 mmol/l (95% CI: -0.02 to 0.09, I (2)=0%) for triglycerides.

AUTHORS' CONCLUSIONS

A modest reduction in salt intake for 4 or more weeks causes significant and, from a population viewpoint, important falls in BP in both hypertensive and normotensive individuals, irrespective of sex and ethnic group. With salt reduction, there is a small physiological increase in plasma renin activity, aldosterone and noradrenaline. There is no significant change in lipid levels. These results provide further strong support for a reduction in population salt intake. This will likely lower population BP and, thereby, reduce cardiovascular disease. Additionally, our analysis demonstrates a significant association between the reduction in 24-h urinary sodium and the fall in systolic BP, indicating the greater the reduction in salt intake, the greater the fall in systolic BP. The current recommendations to reduce salt intake from 9-12 to 5-6 g/d will have a major effect on BP, but are not ideal. A further reduction to 3 g/d will have a greater effect and should become the long term target for population salt intake.

Effects of subacute dietary salt intake and acute volume expansion on diastolic function in young normotensive individuals

AIMS

Chronic excess salt intake may have blood pressure-independent adverse effects on the heart such as myocardial hypertrophy and fibrosis. Effects of subacute sodium loading with excess dietary salt on diastolic function in normotensive individuals have been conflicting and the mechanisms are poorly understood.

METHODS AND RESULTS

Thirteen healthy normotensive subjects (age 24 ± 4 years) entered a 2-week crossover study with 1 week of a low-salt diet <10 mEq/day and 1 week of a high-salt diet >200 mEq/day. At the end of each study week, left ventricular dimensions, systolic, and diastolic function were assessed with echocardiography before and after 2 L of normal saline infusion. One week of high-salt and low-salt diets did not lead to differences in echocardiographic parameters of systolic or diastolic function, even after rapid volume expansion with saline infusion. The peak early diastolic strain rate (SR) increased after volume loading both after completion of low-salt (1.62 ± 0.23/s vs. 1.82 ± 0.14/s, P < 0.05) and high-salt diets (1.67 ± 0.16/s vs. 1.86 ± 0.22/s, P < 0.05). There was a positive correlation between the peak early diastolic SR and the cardiac index (r = 0.52, P = 0.017).

CONCLUSION

In healthy normotensive individuals, subacute excess dietary sodium intake does not affect diastolic function. The peak early diastolic SR, similar to other mitral Doppler and tissue Doppler parameters of diastolic function, appears to be strongly dependent on pre-load.

Hypertension after pediatric cardiac transplantation: detection, etiology, implications and management

While it may rescue children with end-stage heart failure from impending catastrophe, cardiac transplantation leaves 50-70% of pediatric recipients with new-onset hypertension. Given the unique vulnerability of the heart and kidneys in these children, we can expect long-term uncontrolled hypertension to shorten both graft and patient survival. In this review we discuss the multi-factorial etiology of post-transplant hypertension, highlighting current uncertainties and emphasizing mechanisms specific to cardiac recipients. We consider the optimal means of monitoring BP and in particular, the advantages of 24 h-ABP over intermittent clinic measurements. We also review BP treatment after cardiac transplantation, drawing attention to specific cautions appropriate when prescribing antihypertensive agents in these circumstances.

Increasing sodium intake from a previous low or high intake affects water, electrolyte and acid-base balance differently

Contrasting data are published on the effects of high salt intake (between 300 and 660 mmol/d) on Na balance and fluid retention. In some studies high levels of NaCl intake (400, 440, 550 and 660 mmol/d) led to positive Na balances without fluid retention. To test the relevance of different baseline NaCl intake levels on changes in metabolic water, Na, K, chloride and acid-base balance, a 28 d clinical trial ('Salty Life 6') was carried out in a metabolic ward. Nine healthy male volunteers (aged 25.7 (SD 3.1) years; body mass (BM) 71.4 (SD 4.0) kg) participated in the present study. Four consecutive levels of NaCl intake: low (6 d, 0.7 mmol NaCl/kg BM per d), average normal (6 d, 2.8 mmol NaCl/kg BM per d), high (10 d, 7.7 mmol NaCl/kg BM per d), and low again (6 d, 0.7 mmol NaCl/kg BM per d) were tested. Urine osmolality, extracellular volume (ECV) and plasma volume (PV), cumulative metabolic Na, K, chloride and fluid balances, mRNA expression of two glycosaminoglycan (GAG) polymerisation genes, capillary blood pH, bicarbonate and base excess were measured. During average normal NaCl intake, 193 (SEM 19) mmol Na were retained and ECV (+2.02 (SEM 0.31) litres; P<0.001) and PV (+0.57 (SEM 0.13) litres; P<0.001) increased. During high NaCl intake, 244 (SEM 77) mmol Na were retained but ECV did not increase (ECV -0.54 (SEM 0.30) litres, P=0.+89; PV +0.27 (SEM 0.25) litres, P=0.283). mRNA expression of GAG polymerisation genes increased with rise in NaCl intake, while pH (P<0.01) and bicarbonate (P<0.001) levels decreased. We conclude that a high NaCl intake may increase GAG synthesis; this might play a role in osmotically inactive Na retention in humans.

Decreased effective blood volume in edematous disorders: what does this mean?

Edematous patients with renal sodium and water retention, particularly cardiac failure and cirrhosis, have been suggested to have a decreased "effective blood volume." This enigmatic and undefined term was coined because edematous patients were found to have increased, rather than the earlier proposed decreased, blood volumes. This article discusses the advances that have occurred in understanding the pathophysiology of edema as occurs in conditions such as cardiac failure, cirrhosis, and pregnancy. The regulatory mechanisms that lead to increased sodium and water retention by the normal kidney are related to arterial underfilling, as a result of a decrease in cardiac output, arterial vasodilation, or both.

The role of dietary cations in the blood pressure of renal transplant recipients

BACKGROUND

The role of dietary cations in hypertension has been evaluated in the general population and selected subgroups, but its contribution to blood pressure (BP) elevations in patients with functional renal allografts has not been critically examined.

METHODS

After counseling based on Dietary Approaches to Stop Hypertension (DASH) guidelines, we measured timed 24-h urine excretion rates of sodium, potassium, calcium, and magnesium as a surrogate for their dietary intake, in 244 stable adult single-organ renal transplant recipients, correlating these with averaged blinded clinic-measured BP values. Multiple linear regression analysis adjusting for factors affecting BP in transplant recipients was performed.

RESULTS

There was no correlation between systolic (SBP) or diastolic pressure (DBP) and 24-h urine excretion rates of each cation. There was no BP difference between patients receiving cyclosporine and tacrolimus (127/77 vs. 129/78 mmHg, p = 0.38), or in cation excretion except for calcium (2.85 +/- 2.0 vs. 2.90 +/- 2.8, p = 0.002). Protein excretion (p < 0.0001), age (p = 0.002), and weight (p = 0.04) were positively associated with SBP, while only weight (p = 0.01) was associated with DBP by multivariate analysis.

CONCLUSION

Dietary cation intake is not significantly associated with BP in renal transplant recipients. These data do not support recommendations to alter dietary cation intake as part of the management of post-transplantation hypertension.

Role of Dietary Salt Intake in Posttransplant Hypertension With Tacrolimus-Based Immunosuppression

Dietary salt is an important contributor to hypertension in the general population. While its role in cyclosporine-induced hypertension is minimal, its role in tacrolimus-based immunosuppression has not been defined. We measured the 24-hour urine sodium excretion as an estimate of intake in a group of stable renal transplant recipients on tacrolimus (N = 143) who had serum creatinine fluctuations <20% during the preceding 3 months. Average clinic-measured blood pressure (BP) from before and after the 24-hour urine collection was computed. Patients with recent changes in antihypertensive medications were excluded. Average systolic BP was 126 +/- 14 and diastolic BP 76 +/- 7 mm Hg. Urine sodium was 162.6 +/- 70 mmol/d (range 50 to 351), and the sodium/creatinine ratio was 15.4 +/- 6.4. There was no correlation between urine sodium excretion and either systolic or diastolic BP (R = 0.07 and R = 0.05, P = NS) or the sodium/creatinine and systolic/diastolic BP (R = 0.13, R = 0.11, P = NS). By multiple linear regression only weight and urine protein were independently associated with both systolic BP (P < .0001 for each) and diastolic BP (P < .05 for each). In conclusion, there is no appreciable influence of dietary salt intake on BP under tacrolimus-based immunosuppression. Restricting dietary salt intake in these patients cannot be recommended at the current time.

Cyclosporine A and adverse effects on organs: histochemical studies

The discovery that cyclosporine A (CsA) was a powerful immunosuppressant had a significant impact on transplant medicine. Its molecular mechanism of action has been well defined in T cells and involved inhibition of critical signalling pathways that regulated T-cell activation. In fact, CsA inhibited calcineurin phosphatase activity and thereby activation of the transcription factor nuclear factor of activated T cells. Over 10 years, its use is limited by side effects, determining nephro- and hepatotoxicity, gingival hypertrophy, tremor and increased blood pressure. These negative effects have been identified through morphological alterations and/or clinical parameters, i.e. variation in glomerular filtration rate for nephrotoxicity. Nevertheless, CsA remains a therapeutic valuable agent and it is normally utilized into clinical practice even if different dose adjustments or discontinuations in a significant percentage of patients must be used. This review focuses on the following topics: mechanisms of action and drug metabolism, interactions with other drugs, clinical and morphological evaluation of toxic effects on target organs. In particular, the morphological evaluation of negative effects has been considered reporting light and ultrastructural studies on target organs both in normal and immunosuppressive conditions. Moreover, the histochemical and immunohistochemical variations in cellular metabolism and antigenic properties of cells present in the parenchyma of these organs are discussed.

Hormonal, renal, hemodynamic responses to acute neutral endopeptidase inhibition in heart transplant patients

We investigated the hemodynamic, renal, and hormonal responses to neutral endopeptidase (NEP) inhibition during a 6-h, double-blind, randomized, placebo-controlled study in seven chronic, stable heart transplant patients. Baseline characteristics were similar during both experiments, and no significant changes were observed after placebo. NEP inhibition increased circulating endothelin-1 (from 2.01 +/- 0.1 to 2.90 +/- 0.2 pmol/l; P < 0.01), atrial natriuretic peptide (ANP; from 21.5 +/- 2.7 to 29.6 +/- 3.7 pmol/l; P < 0.01), and the ANP second messenger cGMP. Noteworthy, systemic blood pressure did not increase. Renal plasma flow and glomerular filtration rate remained unmodified after NEP inhibition. Filtration fraction (33 +/- 13%), diuresis (196 +/- 62%), and natriuresis (315 +/- 105%) increased significantly in relation to ANP and cGMP. A strong inverse relationship was observed between excreted cGMP and sodium reabsorption (r = -0.71, P < 0.0001). Thus, despite significantly increasing endothelin-1, NEP inhibition did not adversely influence systemic or renal hemodynamics in transplant patients. ANP, possibly through a tubular action, enhances the natriuresis observed after NEP inhibition.

Blood pressure, endothelial function and circulating endothelin concentrations in liver transplant recipients

OBJECTIVES

To study candidates for liver transplant before and 6 weeks after transplant, and to elucidate the role of endothelial dysfunction and plasma endothelin concentrations in the development of hypertension. DESIGN PROSPECTIVE: follow-up study.

SETTING

Institutional, outpatient.

PATIENTS

and controls Fifteen patients (11 men, four women, mean age 46.7+/-13.2 years) with end-stage liver disease (ESLD) and healthy volunteers of comparable age and sex.

METHODS

We performed office blood pressure readings and 24 h ambulatory blood pressure monitoring (ABPM), measurements of endothelial-dependent vasodilatation using high-resolution ultrasound in the brachial artery at rest and during reactive hyperemia, and plasma endothelin-1 assays 3 months before and 6 weeks after the transplant.

RESULTS

Office systolic and diastolic blood pressures increased significantly 6 weeks after liver transplantation (from 116.6+/-14.1 to 139.9+/-19.5 mmHg and from 68.6+/-9.5 to 84.1+/-9.8 mmHg, respectively; both P < 0.001). Hypertension based on office blood pressure readings increased from 6.7 to 40% (P < 0.05). Mean 24 h systolic blood pressure increased from 118.7+/-10.3 to 140.0+/-19.0 mmHg (P < 0.001), mean 24 h diastolic blood pressure increased from 86.0+/-7.7 to 104.8+/-13.9 mmHg (P < 0.001) and heart rate increased from 74.8+/-10.2 to 80.2+/-8.2 beats/min (P < 0.05). Brachial artery flow-mediated dilatation did not change throughout the study (before transplant: 4.2+/-4.0%; after transplant: 6.3+/-5.4%; NS) and did not differ from that in controls (5.2+/-3.8%). Plasma endothelin-1 was increased in patients with ESLD (15.3+/-2.6 pg/ml) compared with controls (5.6+/-0.4 pg/ ml; P < 0.001) and remained unchanged 6 weeks after liver transplantation (14.1+/-3.7 pg/ml).

CONCLUSION

Our results show increased blood pressure with suppressed circadian blood pressure variability in liver graft recipients 6 weeks after transplant and no change in endothelial function and plasma endothelin concentrations. Therefore, the blood pressure increase documented in our study cannot be explained by endothelial dysfunction. Twenty-four hour ABPM should be performed routinely in patients who have undergone liver transplant.

High dietary sodium chloride consumption may not induce body fluid retention in humans

A commonly accepted hypothesis is that a chronically high-sodium diet expands extracellular volume and finally reaches a steady state where sodium intake and output are balanced whereas extracellular volume is expanded. However, in a recent study where the main purpose was to investigate the role of natriuretic peptides under day-to-day sodium intake conditions (Heer M, Drummer C, Baisch F, and Gerzer R. Pflügers Arch 425: 390-394, 1993), our laboratory observed increases in plasma volume without any rise in extracellular volume. To scrutinize these results that were observed as a side effect, we performed a controlled, randomized study including 32 healthy male test subjects in a metabolic ward. The NaCl intake ranged from a low level of 50 meq NaCl/day to 200, 400, and 550 meq/day, respectively. Plasma volume dose dependently increased (P < 0.01), being elevated by 315 +/- 37 ml in the 550-meq-NaCl-intake group. However, in contrast to the increased plasma volume, comparable to study I, total body water did not increase. In parallel, body mass also did not increase. Mean corpuscular volume of erythrocytes, as an index for intracellular volume, was also unchanged. We conclude from the results of these two independently conducted studies that under the chosen study conditions, in contrast to present opinions, high sodium intake does not induce total body water storage but induces a relative fluid shift from the interstitial into the intravascular space.

Regulation of natriuretic peptide secretion by the heart

Secreted by the heart, more specifically by atrial cardiomyocytes under normal conditions but also by ventricular myocytes during cardiac hypertrophy, natriuretic peptides are now considered important hormones in the control of blood pressure and salt and water excretion. Studies on natriuretic peptide secretagogues and their mechanisms of action have been complicated by hemodynamic changes and contractions to which the atria are constantly subjected. It now appears that atrial stretch through mechano-sensitive ion channels, adrenergic stimulation via alpha 1A-adrenergic receptors, and endothelin via its ETA receptor subtype are major triggering agents of natriuretic peptide release. With several other stimuli, such as angiotensin II and beta-adrenergic agents, modulation of natriuretic peptide release appears to be linked to local generation of prostaglandins. In all cases, intracellular calcium homeostasis, controlled by several ion channels, is considered a key element in the regulation of natriuretic peptide secretion.

Effect of standing on neurohumoral responses and plasma volume in healthy subjects

Upright posture leads to rapid pooling of blood in the lower extremities and shifts plasma fluid into surrounding tissues. This results in a decrease in plasma volume (PV) and in hemoconcentration. There has been no integrative evaluation of concomitant neurohumoral and PV shifts with upright posture in normal subjects. We studied 10 healthy subjects after 3 days of stable Na+ and K+ intake. PV was assessed by the Evans blue dye method and by changes in hematocrit. Norepinephrine (NE), NE spillover, epinephrine (Epi), vasopressin, plasma renin activity, aldosterone, osmolarity, and kidney response expressed by urine osmolality and by Na+ and K+ excretion of the subjects in the supine and standing postures were all measured. We found that PV fell by 13% (375 +/- 35 ml plasma) over approximately 14 min, after which time it remained relatively stable. There was a concomitant decrease in systolic blood pressure and an increase in heart rate that peaked at the time of maximal decrease in PV. Plasma Epi and NE increased rapidly to this point. Epi approached baseline by 20 min of standing. NE spillover increased 80% and clearance decreased 30% with 30 min of standing. The increase in plasma renin activity correlated with an increase in aldosterone. Vasopressin increased progressively, but there was no change in plasma osmolarity. The kidney response showed a significant decrease in Na+ and an increase in K+ excretion with upright posture. We conclude that a cascade of neurohumoral events occurs with upright posture, some of which particularly coincide with the decrease in PV. Plasma Epi levels may contribute to the increment in heart rate with maintained upright posture.

Management of the cardiac transplant recipient: roles of the transplant cardiologist and primary care physician

Cardiac transplantation has become an accepted treatment for selected patients with end-stage heart failure. Despite a successful transplant, denervated transplanted hearts respond differently to cardiac drugs than nontransplanted hearts. The treatments for bradycardia, tachycardia, and hypotension are different than for nontransplanted hearts. Despite the improvement in long-term survival, a number of complications may occur posttransplantation. These complications include, allograft rejection, infection, allograft coronary artery disease, and malignancy. Additionally, posttransplant patients may have complications from the immunosuppressive agents cyclosporine, prednisione, and azathioprine. Such complications include drug interactions with commonly prescribed medications, hypertension, hyperlipidemia, osteoporosis, and gastrointestinal complications. The purpose of this article is to discuss the management of the cardiac transplant recipient as it relates to the aforementioned complications. Management of the cardiac transplantation patient by the primary care physician will also be discussed, including indications for consultation by the primary care physician with the transplant center.

Effectiveness and safety of diltiazem or lisinopril in treatment of hypertension after heart transplantation. Results of a prospective, randomized multicenter trail

OBJECTIVES

The purpose of this study was to determine the effectiveness and safety of diltiazem or lisinopril for treatment of hypertension after heart transplantation.

BACKGROUND

Systemic hypertension is common after heart transplantation, and to date there are no randomized, prospective multicenter treatment trials.

METHODS

Members of the Cardiac Transplant Research Database Group developed and implemented a prospective, randomized multicenter trial of the effectiveness and safety of diltiazem or lisinopril in the treatment of hypertension in cyclosporine-treated patients after heart transplantation.

RESULTS

One hundred sixteen patients with hypertension (blood pressure > or = 140/90 mm Hg) after heart transplantation were randomized for > or = 3 months of treatment. Of 55 diltiazem-treated patients, 21 (38%) were responders (diastolic blood pressure < 90 mm Hg), 23 (42%) were nonresponders (diastolic blood pressure > or = 90 mm Hg), and 11 (20%) were withdrawn from the study. Of 61 lisinopril-treated patients, 28 (46%) were responders, 22 (36%) were nonresponders, and 11 (18%) were withdrawn. There was no difference in baseline characteristics or percent responders between the two groups. Systolic pressure decreased from 157 +/- 2.3 to 130 +/- 2.0 mm Hg (mean +/- 1 SEM) in the diltiazem-treated responders and from 153 +/- 2.1 to 127 +/- 2.7 mm Hg in the lisinopril-treated responders (p < 0.0001). Diastolic pressure decreased from 100 +/- 0.9 to 85 +/- 1.6 mm Hg in the diltiazem-treated responders and from 100 +/- 1.0 to 84 +/- 2.0 mm Hg in the lisinopril-treated responders (p < 0.0001). There were a total of 35 reported adverse events, 22 of which led to withdrawal of the patient from the study. All drug-related side effects were considered minor and resolved with discontinuation of the drug.

CONCLUSIONS

These results indicate that both diltiazem and lisinopril are safe for treatment of hypertension after heart transplantation, although titrated monotherapy with either drug controlled the condition in < 50% of patients.

Breakdown of blood pressure and body fluid homeostasis in heart transplant recipients

OBJECTIVES

This study was designed to investigate disturbances in arterial blood pressure and body fluid homeostasis in stable heart transplant recipients.

BACKGROUND

Hypertension and fluid retention frequently complicate heart transplantation.

METHODS

Blood pressure, renal and endocrine responses to acute volume expansion were compared in 10 heart transplant recipients (57 +/- 9 years old [mean +/- SD]) 20 +/- 5 months after transplantation, 6 liver transplant recipients receiving similar doses of cyclosporine (cyclosporine control group) and 7 normal volunteers (normal control subjects). After 3 days of a constant diet containing 87 mEq/24 h of sodium, 0.154 mol/liter saline was infused at 8 ml/kg per h for 4 h. Blood pressure and plasma vasopressin, angiotensin II, aldosterone, atrial natiuretic peptide and renin activity levels were determined before and at 30, 60, 120 and 240 min during the infusion. Urine was collected at 2 and 4 h. Blood pressure, fluid balance hormones and renal function were monitored for 48 h after the infusion.

RESULTS

Blood pressure did not change in the two control groups but increased in the heart transplant recipients (+15 +/- 8/8 +/- 5 mm Hg) and remained elevated for 48 h (p < or = 0.05). Urine flow and urinary sodium excretion increased abruptly in the control groups sufficient to account for elimination of 86 +/- 9% of the sodium load by 48 h; the increases were blunted (p < or = 0.05) and delayed in the heart transplant recipients, resulting in elimination of only 51 +/- 13% of the sodium load. Saline infusion suppressed vasopressin, renin activity, angiotensin II and aldosterone in the two control groups (p < or = 0.05) but not in the heart transplant recipients. Heart transplant recipients had elevated atrial natriuretic peptide levels at baseline (p < or = 0.05), but relative increases during the infusion were similar to those in both control groups.

CONCLUSIONS

Blood pressure in heart transplant recipients is salt sensitive. These patients have a blunted diuretic and natriuretic response to volume expansion that may be mediated by a failure to reflexly suppress fluid regulatory hormones. These defects in blood pressure and fluid homeostasis were not seen in liver transplant recipients receiving cyclosporine and therefore cannot be attributed to cyclosporine alone. Abnormal cardiorenal neuroendocrine reflexes, secondary to cardiac denervation, may contribute to salt-sensitive hypertension and fluid retention in heart transplant recipients.

Cardiac transplantation for the cardiologist not trained in transplantation

This review focuses on selected aspects of the treatment of patients being evaluated for and undergoing cardiac transplantation. Cardiac transplantation is a potential therapeutic option for a variety of irreversible cardiac disorders when the symptomatic status and anticipated survival after transplantation exceeds that of the patient's condition. The timing of cardiac transplantation with respect to prognosis is aided by the measurement of baseline hemodynamics and maximal aerobic capacity. Major cardiac problems that occur after transplantation include an increased early risk of acute allograft rejection and, later, the occurrence of allograft coronary artery disease. Furthermore, cardiac transplant recipients have unique "normal" physiologic alterations with respect to intracardiac hemodynamics, exercise capacity, the effects of denervation, and expected electrocardiographic and echocardiographic findings.