Continuous Pulse Wave Analysis Research Articles

Hemodynamic response to non-pneumatic anti-shock compression garments in patients with renal dysfunction

BackgroundPatients with chronic kidney disease are at higher risk of developing cardiovascular disease. Chronic exposure to intermittent hemodialysis may be a source of added stress to the cardiovascular system; intradialytic hypotension is a common complication of hemodialysis, and repeated events may lead to hemodynamic stress and ischemic injuries. Administration of non-pneumatic compression stockings to the lower limbs has demonstrated hemodynamic stabilizing effects in other settings and may provide similar benefits in the kidney disease population. Therefore, we conducted this pilot study assessing the feasibility and tolerability of the application of non-pneumatic compression stockings to patients with kidney disease. We also assessed the changes in hemodynamic measurements following the application of the compression stockings to explore the biological feasibility of this being an effective intervention for intradialytic hypotension.MethodsFifteen individuals were enrolled in the study (5 healthy, 5 chronic kidney disease patients, and 5 dialysis patients). Outcomes including hemodynamic parameters such as cardiac output, peripheral vascular resistance, and blood pressure were measured using continuous pulse wave analysis. Changes in global longitudinal strain were measured via echocardiography. These outcome measurements were made before and after the application of compression stockings.ResultsAll study participants tolerated the compression garments well and without complication. Hemodynamic response to lower body compression caused varying effects on cardiac output, mean arterial pressure and global longitudinal strain. Some individuals saw large improvements in hemodynamic parameters while in others the opposite effect was observed. No consistent response was elicited.ConclusionsApplication of compression stockings to patients with renal dysfunction is well-tolerated. However, significant variations in hemodynamic outcomes exist, and may be a barrier for larger scale trials without prior identification of specific patient characteristics indicating likely benefit from the application of external compression.Trial registrationClinicalTrials.gov, Identifier: NCT02915627, Registration Date: Sept 27, 2016.

Individualised Dialysate Temperature Improves Intradialytic Haemodynamics and Abrogates Haemodialysis-Induced Myocardial Stunning, without Compromising Tolerability

Background/Aims: Haemodialysis-induced myocardial stunning is associated with intradialytic hypotension, increased likelihood of cardiovascular events and death. Dialysis at 35°C reduces stunning, but adverse thermal symptoms limit technique adoption. This study investigated whether individualised body temperature dialysis improves haemodynamic stability and abrogates stunning. Methods: Randomised crossover study of 11 patients compared LV regional wall motion abnormalities (RWMAs) at 37°C (HD₃₇) and body temperature (‘individualised’, HD_ind). Regional systolic function was quantitatively assessed by echocardiography. Haemodynamics were assessed using continuous pulse wave analysis. Thermal symptoms were scored by questionnaire. Results: Mean predialysis body temperature was 36.0 ± 0.1°C. Mean number of peak stress RWMAs per patient was lower with HD_ind (3.9 ± 1.4 vs. 5.3 ± 1.5, p = 0.03). Intradialytic systolic BP was higher during HD_ind versus HD₃₇ (p < 0.001). Individualised body temperature dialysis demonstrated symptomatic tolerability comparable to HD₃₇. Conclusions: Individualised-temperature haemodialysis abrogates stunning, providing effective haemodynamic stabilisation at no additional therapy cost.

Peritoneal Dialysis is not Associated with Myocardial Stunning

Hemodynamic changes during hemodialysis can precipitate subclinical myocardial ischemia, which over time contributes to the development of cardiac failure and is associated with a poor prognosis. Peritoneal dialysis (PD) is also associated with acute changes in systemic hemodynamics and a similarly high incidence of cardiovascular disease; we therefore sought to examine whether the hemodynamic effects of a PD exchange would be sufficient to induce subclinical myocardial ischemia. 10 patients on PD entered a prospective observational study to determine whether left ventricular (LV) regional wall motion abnormalities (RWMAs) developed following a dialysate exchange. Serial echocardiography with quantitative analysis was used to assess ejection fraction and regional systolic LV function (shortening fraction). Blood pressure (BP) and hemodynamic variables were measured using continuous pulse wave analysis. We observed a very low frequency of RWMA development (5/100 regions). Only 1 patient had more than 1 RWMA and 6 patients were entirely unaffected. Overall mean shortening fraction increased when comparing pre and post values for both 2-chamber (from 3.06% ± 1.5% to 4.26% ± 1.3%, p = 0.001) and 4-chamber (from 3.00% ± 0.7% to 3.67% ± 0.9%, p = 0.021) analyses. Mean arterial pressure fell by a small degree during drainage of dialysate, with a larger rise in BP observed during instillation. These changes were driven by changes in peripheral resistance that fell during drainage and rose during instillation. In contrast to hemodialysis, the acute effects of PD do not result in subclinical myocardial ischemia.

Analysis of cardiovascular responses to passive head‐up tilt using continuous pulse wave analysis and impedance cardiography

Objective. To non‐invasively measure central haemodynamics, arterial stiffness, cardiac function and vascular resistance, with the subject in the supine position and during head‐up tilt, in order to examine the haemodynamic changes associated with alterations in the augmentation index, and to investigate repeatability and reproducibility of the measurement protocol. Material and methods. Thirty‐three healthy volunteers (21–51 years) were investigated using continuous pulse wave analysis from the radial artery with a tonometric sensor, whole‐body impedance cardiography and plethysmographic blood pressure (BP) recordings from the fingers. The measurements were performed with the subject supine and during passive head‐up tilt, and repeated during the same session and on four separate days. Results. During the head‐up tilt, diastolic BP (5.2±0.6 %), heart rate (27.6±1.9 %) and vascular resistance (12.5±1.7 %) increased (all p<0.05), while systolic BP (−3.2±0.6 %), aortic pulse pressure (−23.3±1.4 %), augmentation index (−11.6±0.7 %), aortic reflection time (−7.0±1.0 %), ejection duration (−21.4±0.7 %), stroke volume (−26.1±1.2 %) and cardiac output (−5.0±1.5 %) decreased (all p<0.05). Augmentation index at rest correlated with aortic systolic BP (r = 0.423), aortic reflection time (r = −0.647), pulse wave velocity (r = 0.287) and age (r = 0.480). The change in augmentation index during head‐up tilt correlated with the change in aortic systolic BP (r = 0.469), aortic pulse pressure (r = 0.606), ejection duration (r = 0.374) and heart rate (r = −0.445). According to Bland‐Altman and repeatability index analyses, repeatability and reproducibility of the measurements were good during the same session and on separate days. Conclusions. Combined pulse wave analysis and impedance cardiography with the subject in the supine position and during head‐up tilt is a repeatable and reproducible method for comprehensive investigation of the cardiovascular function.

Abstract 3357: Haemodialysis Induced Contractile Dysfunction is Associated with Acute and Reversible Reduction in Global and Segmental Myocardial Blood Flow

Hemodialysis (HD) is associated with acute cardiac ischemia, as evidenced by the development of regional wall motion abnormalities (RWMAs). Repetitive acute myocardial ischemia may lead to the development of chronic left ventricular (LV) dysfunction. This study utilised serial H 2 15 O PET scans to confirm that the development of HD-induced RWMAs was associated with reduction in myocardial blood flow (MBF). Four prevalent HD patients without angiographically significant coronary artery disease (CAD) had measurements of MBF during standard HD and biofeedback dialysis (BFD). All patients underwent serial measurements of MBF using PET. Echocardiography was used concurrently to assess LV function. Hemodynamic variables were measured using continuous pulse wave analysis. Mean pre-HD MBF was within the normal range. Global MBF was acutely reduced during HD (see figure ) (P&lt;0.002). Segmental MBF was significantly reduced in areas that developed RWMAs compared to those that did not (P&lt;0.001). Not all regions with reduced MBF were functionally affected but a reduction in MBF of &gt;30% from baseline was associated with the development of RWMAs (P&lt;0.01). No significant differences in haemodynamic tolerability, RWMA development or MBF between dialysis modality were observed. HD is associated with repetitive myocardial ischemia which in absence of significant CAD may be due to coronary microvascular dysfunction. Stress induced, segmental LV dysfunction correlates with a matched reduction in MBF. Functional post-stress recovery is consistent with myocardial stunning induced by HD. This process may be an important component in the development of heart failure in chronic HD patients.

Dialysis-Induced Regional Left Ventricular Dysfunction Is Ameliorated by Cooling the Dialysate

Dialysis patients who develop cardiac failure have a poor prognosis. Recurrent subclinical myocardial ischemia is important in the genesis of heart failure in nondialysis patients. It has previously been demonstrated that subclinical ischemia occurs during hemodialysis; therefore, this study examined whether the improved stability of cool-temperature dialysis lessens this phenomenon. Ten patients who were prone to intradialytic hypotension entered a randomized, crossover study to compare the development of dialysis-induced left ventricular (LV) regional wall motion abnormalities (RWMA) at dialysate temperatures of 37 and 35 degrees C. Serial echocardiography with quantitative analysis was used to assess ejection fraction and regional systolic LV function. BP and hemodynamic variables were measured using continuous pulse wave analysis. The severity of thermal symptoms was scored using a simple questionnaire. Forty-nine new RWMA developed in nine patients during hemodialysis with dialysate at 37 degrees C (HD(37)), compared with thirteen RWMA that developed in four patients during HD(35) (odds ratio 3.8; 95% confidence interval 2.1 to 6.9). The majority of RWMA displayed improved function by 30 min after dialysis. Overall, regional systolic LV function was significantly more impaired during HD(37) (P < 0.001). BP was higher during HD(35), with fewer episodes of hypotension as a result of a higher peripheral resistance and no difference in stroke volume. The development of thermal symptoms was heterogeneous, with most patients tolerating HD(35) well. This study confirms previous findings of reversible LV RWMA that develop during hemodialysis. It also shows that this phenomenon can be ameliorated by reducing dialysate temperature, a simple intervention with no cost implications.

Occurrence of Regional Left Ventricular Dysfunction in Patients Undergoing Standard and Biofeedback Dialysis

Cardiac failure and cardiovascular death are extremely prevalent in dialysis patients. Recurrent subclinical myocardial ischemia is important in the genesis of heart failure in nondialysis patients. We examined whether this phenomenon occurs in response to the stress of hemodialysis (HD). Eight patients prone to intradialytic hypotension were recruited for a randomized crossover study to compare the development of left ventricular regional wall motion abnormalities during standard (HD) and biofeedback dialysis. Patients underwent serial echocardiography with quantitative analysis to assess ejection fraction and regional left ventricular systolic function during both types of dialysis. Blood pressure and hemodynamic variables also were measured by using continuous pulse wave analysis. Forty-two new regional wall motion abnormalities developed in all 8 patients during HD compared with 23 regional wall motion abnormalities that developed in 7 patients during biofeedback dialysis (odds ratio, 1.8; 95% confidence interval, 1.1 to 3.0). The majority of regional wall motion abnormalities showed improvement in function by 30 minutes postdialysis. Overall mean regional function was significantly more impaired during HD (P = 0.022). At peak stress, ejection fraction (measured by percentage of change from baseline) was significantly lower during HD (P = 0.043). Blood pressure was higher during biofeedback dialysis, with significantly fewer episodes of hypotension (odds ratio, 2.0; 95% confidence interval, 1.01 to 4.4). Significantly smaller decreases in stroke volume and cardiac output and a greater increment in pulse rate were observed during biofeedback dialysis. This study shows that reversible left ventricular wall motion abnormalities develop during dialysis with ultrafiltration. We also show that this phenomenon can be ameliorated by the improved hemodynamic stability of biofeedback dialysis and therefore is a potential target for intervention.

Effects of Acetate-Free Double-Chamber Hemodiafiltration and Standard Dialysis on Systemic Hemodynamics and Troponin T Levels

Using acetate as a buffer during hemodialysis is recognized to predispose to intradialytic hypotension; however, bicarbonate-based dialysis is not acetate free. Paired hemodiafiltration (PHF) is a novel online acetate-free technique. We investigated whether PHF is capable of abrogating the changes in systemic hemodynamics and troponin T (cTnT) seen with conventional hemodialysis. Twelve patients entered a randomized crossover study. Blood pressure (BP) and a full range of hemodynamic variables were measured throughout PHF and standard dialysis using continuous pulse wave analysis. We also measured predialysis cTnT in 54 stable and unstable dialysis patients. BP was lower during PHF but without increased instability. Stoke volume and cardiac output declined progressively during both treatments but to a much lesser extent during PHF (p = 0.003, p < 0.0001 respectively), whereas peripheral resistance rose to a larger degree during hemodialysis (p < 0.0001). cTnT levels were lower before PHF as compared with hemodialysis (p = 0.023), with levels falling after PHF and rising after hemodialysis (p < 0.0001). In the supplementary patient group, predialysis median serum cTnT was higher in the unstable patients (p = 0.0001). This study demonstrates that PHF (without exposure to acetate) is associated with less deterioration in systemic hemodynamics, maintenance of BP, and less suppression of myocardial contractility as compared with bicarbonate dialysis.