Impact of Renal Congestion in Patients With Secondary Mitral Regurgitation After Mitral Transcatheter Edge-to-Edge Repair.

BACKGROUND: Renal congestion is a potential prognostic factor in patients with heart failure and recently, assessment has become possible with intrarenal Doppler ultrasonography (IRD). The association between renal congestion assessed by IRD and outcomes after mitral transcatheter edge-to-edge repair (TEER) is unknown, so we aimed to clarify renal congestion and its prognostic implications in patients with mitral regurgitation (MR) who underwent TEER using MitraClip system.Methods and Results: Patients with secondary MR who underwent TEER and were assessed for intrarenal venous flow (IRVF) by IRD were classified according to their IRVF pattern as continuous or discontinuous. Of the 105 patients included, 78 patients (74%) formed the continuous group and 27 (26%) were the discontinuous group. Kaplan-Meier analysis revealed significant prognostic power of the IRVF pattern for predicting the composite outcome of all-cause death and heart failure rehospitalization (log-rank P=0.0257). On multivariate Cox regression analysis, the composite endpoint was independently associated with the discontinuous IRVF pattern (hazard ratio, 3.240; 95% confidence interval, 1.300-8.076; P=0.012) adjusted using inverse probability of treatment weighting. CONCLUSIONS: IRVF patterns strongly correlated with clinical outcomes without changes in renal function. Thus, they may be useful for risk stratification after mitral TEER for patients with secondary MR.

Association between intrarenal venous flow from Doppler ultrasonography and acute kidney injury in patients with sepsis in critical care: a prospective, exploratory observational study.

BACKGROUND: Intrarenal venous flow (IRVF) patterns assessed using Doppler renal ultrasonography are real-time bedside visualizations of renal vein hemodynamics. Although this technique has the potential to detect renal congestion during sepsis resuscitation, there have been few studies on this method. We aimed to examine the relationship between IRVF patterns, clinical parameters, and outcomes in critically ill adult patients with sepsis. We hypothesized that discontinuous IRVF was associated with elevated central venous pressure (CVP) and subsequent acute kidney injury (AKI) or death. METHODS: We conducted a prospective observational study in two tertiary-care hospitals, enrolling adult patients with sepsis who stayed in the intensive care unit for at least 24 h, had central venous catheters placed, and received invasive mechanical ventilation. Renal ultrasonography was performed at a single time point at the bedside after sepsis resuscitation, and IRVF patterns (discontinuous vs. continuous) were confirmed by a blinded assessor. The primary outcome was CVP obtained at the time of renal ultrasonography. We also repeatedly assessed a composite of Kidney Disease Improving Global Outcomes of Stage 3 AKI or death over the course of a week as a secondary outcome. The association of IRVF patterns with CVP was examined using Student's t-test (primary analysis) and that with composite outcomes was assessed using a generalized estimating equation analysis, to account for intra-individual correlations. A sample size of 32 was set in order to detect a 5-mmHg difference in CVP between IRVF patterns. RESULTS: Of the 38 patients who met the eligibility criteria, 22 (57.9%) showed discontinuous IRVF patterns that suggested blunted renal venous flow. IRVF patterns were not associated with CVP (discontinuous flow group: mean 9.24 cm H2O [standard deviation: 3.19], continuous flow group: 10.65 cm H2O [standard deviation: 2.53], p = 0.154). By contrast, the composite outcome incidence was significantly higher in the discontinuous IRVF pattern group (odds ratio: 9.67; 95% confidence interval: 2.13-44.03, p = 0.003). CONCLUSIONS: IRVF patterns were not associated with CVP but were associated with subsequent AKI in critically ill adult patients with sepsis. IRVF may be useful for capturing renal congestion at the bedside that is related to clinical patient outcomes.

Kidney vascular congestion exacerbates acute kidney injury in mice.

Heart failure is frequently accompanied by kidney failure and co-incidence of these organ failures worsens the mortality in patients with heart failure. Recent clinical observations revealed that increased kidney venous pressure, rather than decreased cardiac output, causes the deterioration of kidney function in patients with heart failure. However, the underlying pathophysiology is unknown. Here, we found that decreased blood flow velocity in peritubular capillaries by kidney congestion and upregulation of endothelial nuclear factor-κB (NF-κB) signaling synergistically exacerbate kidney injury. We generated a novel mouse model with unilateral kidney congestion by constriction of the inferior vena cava between kidney veins. Intravital imaging highlighted the notable dilatation of peritubular capillaries and decreased kidney blood flow velocity in the congestive kidney. Damage after ischemia reperfusion injury was exacerbated in the congestive kidney and accumulation of polymorphonuclear leukocytes within peritubular capillaries was noted at the acute phase after injury. Similar results were obtained in vitro, in which polymorphonuclear leukocytes adhesion on activated endothelial cells was decreased in flow velocity-dependent manner but cancelled by inhibition of NF-κB signaling. Pharmacological inhibition of NF-κB for the mice subjected by both kidney congestion and ischemia reperfusion injury ameliorated the accumulation of polymorphonuclear leukocytes and subsequent exacerbation of kidney injury. Thus, our study demonstrates the importance of decreased blood flow velocity accompanying activated NF-κB signaling in aggravation of kidney injury. Hence, inhibition of NF-κB signaling may be a therapeutic candidate for the vicious cycle between heart and kidney failure with increased kidney venous pressure.

Sodium Glucose Co-Transporter 2 Inhibitors Improve Renal Congestion and Left Ventricular Fibrosis in Rats With Hypertensive Heart Failure.

BACKGROUND: Elevated central venous pressure (CVP) in heart failure causes renal congestion, which deteriorates prognosis. Sodium glucose co-transporter 2 inhibitor (SGLT2-i) improves kidney function and heart failure prognosis; however, it is unknown whether they affect renal congestion. This study investigated the effect of SGLT2-i on the kidney and left ventricle using model rats with hypertensive heart failure.Methods and Results: Eight rats were fed a 0.3% low-salt diet (n=7), and 24 rats were fed an 8% high-salt diet, and they were divided into 3 groups of untreated (n=6), SGLT2-i (canagliflozin; n=6), and loop diuretic (furosemide; n=5) groups after 11 weeks of age. At 18 weeks of age, CVP and renal intramedullary pressure (RMP) were monitored directly by catheterization. We performed contrast-enhanced ultrasonography to evaluate intrarenal perfusion. In all high-salt fed groups, systolic blood pressure was elevated (P=0.287). The left ventricular ejection fraction did not differ among high-salt groups. Although CVP decreased in both the furosemide (P=0.032) and the canagliflozin groups (P=0.030), RMP reduction (P=0.003) and preserved renal medulla perfusion were only observed in the canagliflozin group (P=0.001). Histological analysis showed less cast formation in the intrarenal tubule (P=0.032), left ventricle fibrosis (P<0.001), and myocyte thickness (P<0.001) in the canagliflozin group than in the control group. CONCLUSIONS: These results suggest that SGLT2-i causes renal decongestion and prevents left ventricular hypertrophy, fibrosis, and dysfunction.

Prognostic Impact of Changes in Intrarenal Venous Flow Pattern in Patients With Heart Failure.

BACKGROUND: It remains unclear whether intrarenal venous flow (IRVF) patterns in patients with heart failure (HF) could change over the clinical course, and whether the changes could have a clinical impact. Thus, this study aimed to clarify these characteristics as well as to identify the relation between changes in the IRVF pattern and renal impairment progression. METHODS AND RESULTS: Patients with HF with repetitive IRVF evaluations were enrolled. Doppler waveforms of IRVF were classified into the following 3 flow patterns: continuous, biphasic discontinuous, and monophasic discontinuous. Primary end points included death from cardiovascular diseases and unplanned hospitalization for HF. Finally, 108 patients with adequate images were enrolled. The IRVF in 35 patients (32.4%) shifted to another pattern at the follow-up examinations. The median brain natriuretic peptide level in the continuous flow pattern at follow-up was significantly decreased (183 to 60 pg/mL, P < .001), whereas that of the discontinuous flow pattern at follow-up was increased (from 339 to 366 pg/mL, P = .042) and the estimated glomerular filtration rate was decreased (from 55 to 50 mL/min/1.73 m2, P = .013). A multivariable Cox proportional hazard model analysis revealed that the discontinuous pattern at follow-up (P < .001) and brain natriuretic peptide (P = .021) were significantly associated with the end points, independent of age, estimated glomerular filtration rate, and serum sodium level. CONCLUSIONS: The IRVF pattern could be changed depending on the status of congestion. Persistent or worsened renal congestion, represented by discontinuous flow patterns, during the clinical courses indicated a poor prognosis accompanied by renal impairment in patients with HF.

A Potential Mechanism of Cardio-Renal Protection with Sodium-Glucose Cotransporter 2 Inhibitors: Amelioration of Renal Congestion.

BACKGROUND: This review considers anew the etiology of the cardio-renal protective effect of sodium-glucose cotransporter 2 (SGLT2) inhibitors by extending the discussion to renal congestion, inherent in diabetic kidney disease (DKD) even at an early stage of nephropathy in which heart failure (HF) or salt and water accumulation is asymptomatic. SUMMARY: The interstitial fluid (IF) space of the kidney space plays a crucial role for tubulointerstitial inflammation, renal hypoxia, and ischemic injury, which often leads to renal progression. In DKD, as a result of hyperglycemic milieu, excessive salt and water can be accumulated in the IF space, creating renal congestion. I hypothesize that SGLT2 inhibitors cause a shift in extracellular water from the IF space to the intravascular space to compensate for the SGLT2 inhibitor-induced hypovolemia. This decrease in IF volume ameliorates the IF space milieu and may reduce inflammation, hypoxia, and ischemic injury. Message: The present review proposes a novel theory; unlike other hypoglycemic agents or diuretics, SGLT2 inhibitor could protect DKD from failing by improving latent renal congestion even without symptomatic HF.

Renal vein dilation predicts poor outcome in patients with refractory cirrhotic ascites.

AIM: Renal venous hypertension is known to be associated with worsening of renal function in patients with decompensated heart failure. Intra-abdominal hypertension including cirrhotic ascites also leads to renal venous hypertension. We aimed to clarify the effect of renal venous hypertension on cirrhotic ascites. METHODS: Two hepatologists measured the left renal vein diameter in 142 consecutive patients with refractory cirrhotic ascites using non-contrast computed tomography. The renal vein diameter was measured at the renal vein main trunk and upstream of the confluence of collateral veins. RESULTS: The inter-observer agreements were high for the measurements of the left renal vein (r = 0.918, P < 0.001). The median overall survival for patients with renal vein diameter ≥11 mm was less than that for patients with renal vein diameter <11 mm (P < 0.001; 2.5 vs. 32.0 months). One-year survival rates were 15.3% versus 66.4%. Multivariate analysis revealed renal vein diameter ≥11 mm (hazard ratio, 2.94; P < 0.001; 95% confidence interval, 1.67-5.20) and a high Model for End-stage Liver Disease score combined with serum sodium level (MELD-Na) (hazard ratio, 3.39; P < 0.001; 95% confidence interval, 2.00-5.74) were significant independent predictors of mortality. CONCLUSIONS: Renal vein dilation is a risk factor of mortality in patients with refractory cirrhotic ascites, independent of the MELD-Na score.

Assessment of renal perfusion impairment in a rat model of acute renal congestion using contrast-enhanced ultrasonography.

Renal congestion is caused by elevated central venous pressure (CVP), and decreases glomerular filtration in patients with congestive heart failure. Since real-time contrast-enhanced ultrasonography (CEUS) using microbubble-based contrast agents can visualize the perfused microvascular bed, we sought to evaluate the impairment of renal perfusion during acute renal congestion with CEUS. In Wister rats, CEUS of kidney was performed with the direct monitoring of CVP and intra-renal pressure (IRP). When CVP was elevated to 10 and 15 mmHg after the bolus injection of normal saline via the femoral vein, peak intensity (PI, dB) and time to PI (TTP) in the renal cortex and medulla were compared with control rats. There was a strong correlation between IRP and CVP (r = 0.95, p < 0.0001). In the congestion model, more time was required for enhancement of the parenchyma, especially in the medulla compared to control; TTP of the medulla and cortex at 15 mmHg CVP (CVP15) was significantly prolonged compared with controls (medulla, 4351 ± 98 vs. 1415 ± 267 ms, p = 0.003; cortex, 3219 ± 106 vs. 1335 ± 264 ms, p = 0.005). In addition, medullary PI at CVP15 decreased, but not significantly, compared to those of controls and at 10 mmHg CVP (20.1 ± 0.9, 22.8 ± 1.6, 21.6 ± 0.2 dB). In contrast, cortical PIs at CVP15 were significantly lower than that of control (24.6 ± 1.0 vs. 31.4 ± 1.0 dB, p = 0.007). CEUS revealed that impaired renal parenchymal flow in an acute congestion model is accompanied with increased renal interstitial pressure.

Diuretic usage for protection against end-organ damage in liver cirrhosis and heart failure.

Volume overload is common in liver cirrhosis, heart failure, and chronic kidney disease, being an independent risk factor for mortality. Loop diuretics have been widely used for treating volume overload in these patients. However, there is a tendency to increase the dose of loop diuretics partly because of diuresis resistance. Neurohormonal factors are also enhanced in these patients, which play a role in volume overload and organ ischemia. Loop diuretics cannot improve neurohormonal factors and could result in end-organ damage. The water diuretic tolvaptan has been approved for use for volume overload in heart failure and liver cirrhosis. Despite causing similar increases in urine volume, its characteristics differ from those of loop diuretics. Renal blood flow is maintained with tolvaptan but decreased with furosemide in heart failure patients. Neurohormonal factors and blood pressure are not markedly altered by tolvaptan administration. It is expected that these mechanisms of tolvaptan can protect against worsening renal function by volume overload diseases compared with loop diuretics. It has also been reported that some patients do not respond well to tolvaptan. Loop diuretics and tolvaptan share the same mechanism with regard to decreasing renal interstitial osmolality, which plays a fundamental role in water diuresis. Thus, a high dose of loop diuretics could result in resistance to tolvaptan, so tolvaptan should be administered before increasing the loop diuretic dose. Therefore, volume control without enhancing end-organ damage can be achieved by adding tolvaptan to a tolerable dose of Na-sparing diuretics.

Fluid overload is an independent risk factor for acute kidney injury in critically Ill patients: results of a cohort study.

BACKGROUND: Acute Kidney injury (AKI) is common and increases mortality in the intensive care unit (ICU). We carried out this study to explore whether fluid overload is an independent risk factor for AKI. METHODS: Single-center prospective, observational study. Consecutively admitted, ICU patients were followed for development of AKI. Intravenous fluid volumes, daily fluid balances were measured, hourly urine volumes, daily creatinine levels were recorded. RESULTS: Three hundred thirty nine patients were included; AKI developed in 141 (41.6%) patients; RISK in 27 (8%) patients; INJURY in 25 (7%); FAILURE in 89 (26%) by the RIFLE criteria. Fluid balance was significantly higher in patients with AKI; 1755 ± 2189 v/s 924 ± 1846 ml, p < 0.001 on ICU day 1. On multivariate regression analysis, a net fluid balance in first 24 h of ICU admission, OR 1.02 (95% CI 1.01,1.03 p = 0.003), percentage of fluid accumulation adjusted for body weight OR1.009 (95% CI 1.001,1.017, p = 0.02), fluid balance in first 24 h of ICU admission with serum creatinine adjusted for fluid balance, OR 1.024 (95% CI 1.012,1,035, p = 0.005), Age, OR 1.02 95% CI 1.01,1.03, p < 0.001, CHF, OR 3.1 (95% CI 1.16,8.32, p = 0.023), vasopressor requirement on ICU day one, OR 1.9 (95% CI 1.13,3.19, p = 0.014) and Colistin OR 2.3 (95% CI 1.3, 4.02, p < 0.001) were significant predictors of AKI. There was no significant association between fluid type; Chloride-liberal, Chloride-restrictive, and AKI. CONCLUSIONS: Fluid overload is an independent risk factor for AKI.

Assessment of renal congestion in a rat model with congestive heart failure using superb microvascular imaging.

PURPOSE: Renal congestion is a therapeutic target in congestive heart failure. However, its detailed evaluation in a clinical setting is challenging. This study sought to assess renal congestion impairment using superb microvascular imaging (SMI), a simple and accessible method. METHODS: Dahl salt-sensitive rats, used as a model for congestive heart failure, underwent central venous pressure (CVP) measurements. Renal congestion was evaluated through measurements of renal medullary pressure (RMP) and assessment of renal perfusion using contrast-enhanced ultrasonography at both the early (control group) and heart failure phases (HF group). All rats were assessed with SMI. The region of interest (ROI) was set in interlobular vessels, interlobar vessels, and a combination of these areas. The area ratio was calculated from the color pixel count in the ROI divided by the total pixel count in the ROI. Intrarenal perfusion index (IRPI) was defined as (maximum area ratio-minimum area ratio) / maximum area ratio. RESULTS: There were no significant differences in renal function and left ventricular ejection fraction between the two groups. CVP, time-to-peak (TTP) in the medulla, and RMP were higher in the HF group than in the control group. In the HF group, IRPI, evaluated in the interlobular vessels, was significantly higher than in the control group. IRPI was positively correlated with TTP in the medulla (p = 0.028, R = 0.60) and RMP (p < 0.001, R = 0.84), indicating that IRPI reflected renal congestion. CONCLUSIONS: IRPI is a useful tool for assessing renal congestion in rats with congestive heart failure.

Intrarenal Venous Flow Pattern Changes Do Relate With Renal Function Alterations in Acute Heart Failure.

BACKGROUND: There is scarce evidence supporting the clinical utility of congestive intrarenal venous flow (IRVF) patterns in patients with acute heart failure. OBJECTIVES: This study aims to: 1) investigate the association between IRVF patterns and the odds of worsening renal function (WRF); 2) track the longitudinal changes of serum creatinine (sCr) across IRVF at predetermined points and its association with decongestion; and 3) explore the relationship between IRVF/WRF categories and patient outcomes. METHODS: IRVF was assessed at baseline (pre-decongestive therapy), 72 hours, and 30 and 90 days postdischarge. Changes in sCr trajectories across dynamic IRVF variations and parameters of decongestion were assessed using linear mixed effect models. The association between IRVF/WRF categories and outcomes was evaluated using univariable/multivariable models. RESULTS: In this prospective, multicenter study with 188 participants, discontinuous IRVF patterns indicated higher odds of WRF (OR: 3.90 [95% CI: 1.24-12.20]; P = 0.020 at 72 hours; and OR: 5.76 [95% CI: 1.67-19.86]; P = 0.006 at 30 days) and an increase in sCr (Δ-72 hours 0.14 mg/dL [95% CI: 0.06-0.22]; P = 0.001; Δ-discharge 0.13 mg/dL [95% CI: 0.03-0.23]; P = 0.007). However, the diuretic response and decongestion significantly influenced the magnitude of these changes. Patients exhibiting both WRF and discontinuous IRVF at 30 days experienced an increased hazard of adverse events (HR: 5.96 [95% CI: 2.63-13.52]; P < 0.001). CONCLUSIONS: Discontinuous IRVF identifies patients with higher odds of WRF during admission and postdischarge periods. Nonetheless, adequate diuretic response and decongestion could modify this association. Patients showing both WRF and discontinuous IRVF at 30 days had increased rates of adverse events.

Sodium glucose cotransporter 2 inhibitor suppresses renal injury in rats with renal congestion.

Renal congestion is an issue of cardiorenal syndrome in patients with heart failure. Recent clinical and basic studies suggest a renoprotective potential of sodium-glucose cotransporter (SGLT) 2 inhibitors. However, the effect on renal congestion and its mechanism is not fully understood. Thus, we aimed to clarify the effect of SGLT inhibition in a renal congestion model. Renal congestion was induced in the left kidney of male Sprague-Dawley rats by ligation of the inferior vena cava between the renal veins. The SGLT2 inhibitor tofogliflozin or vehicle was orally administered daily from the day before IVC ligation until two days after surgery. On the third postoperative day, both the right control kidney and the left congested kidney were harvested and analyzed. Kidney weight and water content was increased, and renal injury and fibrosis were observed in the left congested kidney. Kidney weight gain and hydration were improved with tofogliflozin treatment. Additionally, this treatment effectively reduced renal injury and fibrosis, particularly in the renal cortex. SGLT2 expression was observed in the congested kidney, but suppressed in the damaged tubular cells. Molecules associated with inflammation were increased in the congested kidney and reversed by tofogliflozin treatment. Mitochondrial dysfunction provoked by renal congestion was also improved by tofogliflozin treatment. Tofogliflozin protects against renal damage induced by renal congestion. SGLT2 inhibitors could be a candidate strategy for renal impairment associated with heart failure.

Pericyte detachment and renal congestion involve interstitial injury and fibrosis in Dahl salt-sensitive rats and humans with heart failure.

Congestive heart failure produces fluid volume overload, central and renal venous pressure elevation, and consequently renal congestion, which results in worsening renal function. Pericyte detachment and pericyte-myofibroblast transition (PMT) were linked to renal interstitial fibrosis. Dahl salt-sensitive hypertensive (DahlS) rats are a non-surgical renal congestion model. The relation, however, between renal interstitial damage, pericyte morphology, and PMT in the renal congestion of DahlS rats has not been reported. DahlS rats (8-week-old) were fed normal salt (NS, 0.4% NaCl) or high salt (HS, 4% NaCl), and the left kidney was decapsulated to reduce renal interstitial hydrostatic pressure (RIHP) at 9 weeks old. One week after capsulotomy, both kidneys were analyzed by molecular and histological techniques. Renal pericyte structure was assessed in the body donors with/without venous stasis. Markers of tubulointerstitial damage, interstitial fibrosis, and PMT were upregulated in the right non-decapsulated kidney of DahlS rats fed HS. Renal tubular injury and fibrosis were detected in the HS diet groups in histological analysis. Pericyte detachment was observed in the right non-decapsulated kidney of DahlS rats fed HS by low vacuum-scanning electron microscopy. Decapsulation in DahlS rats fed HS attenuated these findings. Also, renal pericytes detached from the vascular wall in patients with heart failure. These results suggest that pericyte detachment and PMT induced by increased RIHP are responsible for tubulointerstitial injury and fibrosis in DahlS rats and humans with renal congestion. Renal venous congestion and subsequent physiological changes could be therapeutic targets for renal damage in cardiorenal syndrome.

SGLT2 inhibitors in the treatment of type 2 cardiorenal syndrome: Focus on renal tubules.

The pathogenesis of type 2 cardiorenal syndrome (CRS) is mostly associated with reduced cardiac output, increased central venous pressure (CVP), activation of the renin-angiotensin-aldosterone system (RAAS), inflammation, and oxidative stress. As a drug to treat diabetes, sodium-glucose transporter 2 inhibitor (SGLT2i) has been gradually found to have a protective effect on the heart and kidney and has a certain therapeutic effect on CRS. In the process of chronic heart failure (CHF) leading to chronic renal insufficiency, the renal tubular system, as the main functional part of the kidney, is the first to be damaged, but this damage can be reversed. In this review, we focus on the protective mechanisms of SGLT2i targeting renal tubular in the treatment of CRS, including natriuresis and diuresis to relieve renal congestion, attenuate renal tubular fibrosis, improve energy metabolism of renal tubular, and slow tubular inflammation and oxidative stress. This may have beneficial effects on the treatment of CRS and is a direction for future research.

Case report: SGLT2i, transcutaneous vagus nerve stimulation, and their effects on intrarenal venous flow pattern in HFpEF.

Renal congestion in heart failure (HF) is a predictor of the prognosis of cardiovascular disease. The effect of sodium-glucose cotransporter 2 inhibitors (SGLT2i) and vagus nerve stimulation (VNS) on renal congestion has not been reported in HF. A 77-year-old man with HF with preserved ejection fraction (HFpEF) was referred to our hospital because of poor response to loop diuretics. Echocardiography showed severe tricuspid regurgitation with dilation of the right atrium. Three months after adding SGLT2i, body weight was lost without worsening of renal function. Left and right doppler-derived intrarenal venous flow (IRVF) has been changed from a monophasic to a discontinuous pattern with a systolic interruption. One month later, he discontinued SGLT2i administration at his own discretion. In order to stabilizing autonomic balance, transcutaneous VNS (tVNS) was performed via left ear tragus. One hour after transcutaneous tVNS, ipsilateral IRVF has been dramatically improved from a fusional biphasic to a discontinuous pattern with a systolic interruption. SGLT2i and tVNS may be associated with renal decongestion in HFpEF.

Renal vein measurement using ultrasonography in patients with cirrhotic ascites and congestive heart failure.

PURPOSE: Ascites can cause compression of the inferior vena cava (IVC), leading to increased renal venous pressure and renal congestion. Previously, the left renal vein diameter in liver cirrhosis patients with ascites was measured using computed tomography, showing that enlargement of the left renal vein diameter affects the prognosis. Herein, the diameter and flow velocity of the renal veins were measured using ultrasonography. METHODS: Abdominal ultrasonography was performed on 186 patients. The patients were divided into four groups: normal liver (n = 102), liver cirrhosis (LC) without ascites (n = 37), LC with ascites (n = 30), and congestive liver (n = 17). Ultrasonographic measurements for diameter and flow velocity of the IVC, left renal vein main trunk, and segmental renal vein were performed. RESULTS: The left renal vein diameter increased in the following order: normal liver, LC, LC with ascites, and congestive liver groups (P < 0.001). IVC flow velocity was lower and left renal vein diameter was larger in the congestive liver and LC with ascites groups. These results suggest that the two groups have different pathological conditions, but the mechanism of renal congestion is similar. In patients with LC, IVC compression due to ascites might cause blood stagnation and renal congestion. CONCLUSION: The left renal vein and IVC can be measured using ultrasonography. It might help in furthering our understanding of the pathophysiology of renal congestion in these patients.

Disorders in Blood Circulation As a Probable Cause of Death in Dogs Infected with Babesia Canis.

INTRODUCTION: The purpose of the study was to investigate post-mortem changes in dogs infected with Babesia canis and to establish the probable cause of death of the affected animals. MATERIAL AND METHODS: Cadavers of six dogs that did not survive babesiosis were collected. Necropsies were performed and samples of various organs were collected for histological examination. RESULTS: Necropsies and histological examinations revealed congestion and oedemata in various organs. Most of the dogs had ascites, hydrothorax or hydropericardium, pulmonary oedema, pulmonary, renal, hepatic, and cerebral congestion, and necrosis of cardiomyocytes. CONCLUSION: These results suggested disorders in blood circulation as the most probable cause of death. However, the pulmonary inflammatory response and cerebral babesiosis observed in some of these dogs could also be considered possible causes of death. This study also showed a possible role for renal congestion in the development of renal hypoxia and azotaemia in canine babesiosis.

Renoprotective effects of tolvaptan in hypertensive heart failure rats depend on renal decongestion.

The vasopressin type 2 receptor antagonist tolvaptan may have renoprotective effects in patients with heart failure (HF). This study aimed to reveal the renoprotective effect of tolvaptan from the viewpoint of hemodynamic combined with catheter and ultrasound examinations in a hypertensive HF model. Dahl salt-sensitive rats (n = 24) were fed an 8% high-salt diet after the age of 6 weeks and were treated with tolvaptan (n = 16) or vehicle (control group; n = 8). The tolvaptan-treated rats were divided into two groups: a low-dose group (0.01% tolvaptan diet; Low-Tol) and a high-dose group (0.05% tolvaptan diet; High-Tol). At 24 weeks, catheterizations to measure central venous pressure (CVP) and renal medullary pressure (RMP) were performed, followed by intrarenal Doppler (IRD) studies and contrast-enhanced ultrasonography (CEUS) to evaluate renal medullary perfusion. The tolvaptan diet reduced CVP (7.7 ± 1.5, 9.0 ± 1.1, and 12.2 ± 0.8 mmHg in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001) and RMP (7.7 ± 0.8, 9.4 ± 1.3, and 13.7 ± 1.2 mmHg in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001). Tolvaptan also reduced the venous impedance index (VII) in the IRD analysis (0.18 ± 0.03, 0.26 ± 0.04, and 0.40 ± 0.08 in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001), and the time to peak intensity in CEUS (6.0 ± 0.5, 7.3 ± 1.3, 9.8 ± 1.8 s in the High-Tol, Low-Tol, and control groups, respectively; p < 0.001). Creatinine clearance (Ccr) was preserved in both the High-Tol and Low-Tol groups compared to the control group (4.80 ± 1.9, 4.24 ± 0.8, and 1.35 ± 0.3 mg/min, respectively; p = 0.001). Ccr was negatively correlated with RMP (R = -0.76, P < 0.001), the venous impedance index (R = -0.70, p < 0.001), time to peak intensity (R = -0.75, P < 0.001), and renal fibrosis (R = -0.70, p < 0.001). In contrast, Ccr had modest correlations with systolic blood pressure (R = -0.50, P = 0.02) and left ventricular ejection fraction (R = 0.48, P = 0.03). This study revealed that the renoprotective effects of tolvaptan in a hypertensive HF model depended on renal decongestion.