Diuretic Resistance Associated With Heart Failure

A Snake Toxin Derivative for Treatment of Hyponatremia and Polycystic Kidney Diseases

Key Points

MQ232, a disulfide-bond reticulated peptide derived from a natural snake toxin, was optimized as a new aquaretic drug candidate. MQ232 showed very low acute and chronic toxicity in rat and a biodistribution in mice strongly in favor of the kidney organs. MQ232 induced a sole aquaretic effect and demonstrated high in vivo activities on hyponatremia and polycystic kidney disease models.

Background

Vaptans were developed at the end of the previous century as vasopressin type 2 receptor antagonists. Tolvaptan is the most prescribed vaptan for hyponatremia and autosomal dominant polycystic kidney disease (ADPKD). However, its use is not as widespread as it should be due to price issues, a narrow therapeutic window, and some side effects. With the aim of discovering new efficient and safer vasopressin type 2 receptor antagonists, we screened animal venoms and identified several peptide toxins. Among them, mambaquaretin 1 (MQ1) displayed unique biological properties in that regard that it was the starting point for the development of a potential drug candidate.

Methods

Human T-cell assays and bioinformatics were used to mitigate MQ1 immunogenicity risk. MQ232 biodistribution in mice was performed by positron emission tomography. Pharmacodynamics, pharmacokinetics, and acute and chronic toxicity tests were performed on control rats. A rat experimental model of desmopressin-induced hyponatremia, ex vivo mice model of kidney cysts, and mice orthologous model of ADPKD were used to validate MQ232 efficacy in these pathologies.

Results

Three mutations were introduced in MQ1 to mitigate its immunogenicity risk. A fourth gain-of-function mutation was added to generate MQ232. MQ232's safety was demonstrated by a first toxic dose as high as 3000 nmol/kg and a strong kidney organ selectivity by positron emission tomography imaging, while showing almost no interaction with the liver. MQ232's efficacy was first demonstrated with an effective dose of 3 nmol/kg in a hyponatremic model and then in polycystic kidney models, on which MQ232 significantly reduced cyst growth.

Conclusions

We demonstrated, using diverse translational techniques and minimizing animal use, MQ232's safety and efficacy in several rodent models of hyponatremia and ADPKD.

[Effects and Efficacy of Wenyang Huayin Yangxin Prescription on the Traditional Chinese Medicine Syndromes of Patients With Chronic Heart Failure Combined With Diuretic Resistance]

Objective

To study the traditional Chinese medicine (TCM) syndromes of patients with chronic heart failure (CHF) combined with diuretic resistance by using the Wenyang Huayin Yangxin Prescription, and to observe its therapeutic efficacy.

Methods

A total of 68 CHF patients complicated with diuretic resistance and who had Yangqi deficiency and presenting blood stasis syndrome combined with Tanyin were randomly assigned to a control group and an observation group. The control group was given intravenous furosemide (≥ 80 mg/d) via infusion pump in addition to standard Western medical treatment, while the observation group was given intravenous furosemide (< 80 mg/d) via infusion pump along with the Wenyang Huayin Yangxin Prescription (30 g Astragalus, 15 g Poria, 15 g Baizhu, 15 g Chuanxiong, 10 g Danfu tablet, 10 g Cassia, 10 g Alisma, and 10 g Zhimu). The quantitative index of diuretic resistance was used as the primary outcome measure. In addition, the differences between the two groups in TCM syndromes, cardiac function-related indicators, incidence of endpoint events, and readmission rate were compared.

Results

After 2 weeks of treatment, the filtration sodium excretion fraction (FENa) in the observation group was (0.18 ± 0.04)%, while that of the control group was (0.16 ± 0.03)%, showing a statistically significant difference (P = 0.037). The 24-hour urine volume and urine Na+/K+ ratio in the observation group increased significantly from baseline levels and were higher than those in the control group (P < 0.05). The differences in the changes of 24-hour urine volume, urine sodium, FENa, and urine Na+/K+ ratio between the two groups were statistically significant (P < 0.05). The TCM syndrome scores decreased in both groups after 2 weeks of treatment, with the observation group showing a significantly greater reduction compared with the control group (P < 0.001). The differences in the changes of TCM syndrome scores between the two groups were statistically significant (P < 0.001). After 2 weeks of treatment, the observation group showed significant improvements in palpitations, shortness of breath, facial and limb edema, spontaneous sweating, chest tightness (pain), asthma, and oliguria compared with the baseline data (P < 0.05), while the control group showed improvements only in facial and limb edema, asthma, and oliguria (P < 0.05). Except for the asthma syndrome after 2 weeks of treatment, the observation group showed better outcomes in spontaneous sweating, chest tightness (pain), asthma, and oliguria at various time points after treatment compared with the control group (P < 0.05). After 2 weeks of treatment, the observation group had significantly better cardiac output (CO) and stroke volume (SV) compared with those of the control group (P < 0.05). The differences in the changes in N-terminal pro-brain natriuretic peptide (NT-proBNP), left ventricular ejection fraction (LVEF), SV, and CO between the two groups were statistically significant (P < 0.05). After 24 weeks of follow-up, no significant differences in the incidence of end-point events or readmission rates between the two groups were observed.

Conclusion

The Wenyang Huayin Yangxin Prescription, combined with low-dose intravenous furosemide administered through an infusion pump, can improve the TCM syndromes of patients with Yangqi deficiency and blood stasis syndrome combined with Tanyin in addition to CHF complicated by diuretic resistance. This treatment improves the patients' heart function and diuretic resistance, reduces the intravenous dosage of diuretic, and enhances clinical efficacy. This approach should be more widely applied in clinical settings.

Blunted cardiovascular responses to exercise by inhibiting afferent feedback via spinal cord stimulation in heart failure

This case study investigated the impact of SCS on alterations in blood pressure during constant-load exercise in a female patient with heart failure. Three different SCS frequencies [No SCS (~0 Hz), Low SCS (~100 Hz), and High SCS (~1000 Hz)] with and without ischaemic stimulation of the legs (cuffs) were randomly applied during constant-load exercise. To determine cardiovascular and ventilatory responses to exercise following SCS frequencies, BP, heart rate (HR), and respiratory gas exchange were measured. This experiment was duplicated in visit 1 and visit 2 with a random application of SCS frequency order and the data were averaged. There were no significant differences among three frequencies with no leg ischaemia. However, High SCS demonstrated lower BP, HR, and respiratory gas exchange relative to No SCS and Low SCS. SCS may be effective in improving cardiovascular and ventilatory responses in HF and high-frequency stimulation provides more clinical benefit; however, further studies are needed.

Acetazolamide as an Adjunctive Diuretic Therapy for Patients with Acute Decompensated Heart Failure: A Systematic Review and Meta-Analysis

BACKGROUND

Recent evidence suggests that acetazolamide may be beneficial as an adjunctive diuretic therapy in patients with acute decompensated heart failure (HF). We aim to pool all the studies conducted until now and provide updated evidence regarding the role of acetazolamide as adjunctive diuretic in patients with acute decompensated HF.

METHODS

PubMed/Medline, Cochrane Library, and Scopus were searched from inception until July 2023, for randomized and nonrandomized studies evaluating acetazolamide as add-on diuretic in patients with acute decompensated HF. Data about natriuresis, urine output, decongestion, and the clinical signs of congestion were extracted, pooled, and analyzed. Data were pooled using a random effects model. Results were presented as risk ratios (RRs), odds ratios (ORs), or weighted mean differences (WMD) with 95% confidence intervals (95% CIs). Certainty of evidence was assessed using the grading of recommendation, assessment, development, and evaluation (GRADE) approach. A P value of < 0.05 was considered significant in all cases.

RESULTS

A total of 5 studies (n = 684 patients) were included with a median follow-up time of 3 months. Pooled analysis demonstrated significantly increased natriuresis (MD 55.07, 95% CI 35.1-77.04, P < 0.00001; I2 = 54%; moderate certainty), urine output (MD 1.04, 95% CI 0.10-1.97, P = 0.03; I2 = 79%; moderate certainty) and decongestion [odds ratio (OR) 1.62, 95% CI 1.14-2.31, P = 0.007; I2 = 0%; high certainty] in the acetazolamide group, as compared with controls. There was no significant difference in ascites (RR 0.56, 95% CI 0.23-1.36, P = 0.20; I2 = 0%; low certainty), edema (RR 1.02, 95% CI 0.52-2.0, P = 0.95; I2 = 45%; very low certainty), raised jugular venous pressure (JVP) (RR 0.86, 95% CI 0.63-1.17, P = 0.35; I2 = 0%; low certainty), and pulmonary rales (RR 0.82, 95% CI 0.44-1.51, P = 0.52; I2 = 25%; low certainty) between the two groups.

CONCLUSIONS

Acetazolamide as an adjunctive diuretic significantly improves global surrogate endpoints for decongestion therapy but not all individual signs and symptoms of volume overload.

SYSTEMATIC REVIEW REGISTRATION

This systematic review was prospectively registered on the PROSPERO ( https://www.crd.york.ac.uk/PROSPERO/ ), registration number CRD498330.