Download Spring 2005 - The Scottish Renal Registry

Can the stop dialysate flow method be used to assess adequacy in
patients receiving haemodiafiltration?
JP Traynor1, HA Oun2, P McKenzie3, IR Shilliday2, IG McKay3, A Dunlop3, CC Geddes1, RA
Mactier4
1 Renal Unit, Western Infirmary, Glasgow
2 Renal Unit, Monklands Hospital, Airdrie
3 Renal Unit, Crosshouse Hospital, Kilmarnock
4 Renal Unit, Glasgow Royal Infirmary, Glasgow
Abstract
Background
The stop dialysate flow (SDF) method of post dialysis urea sampling is the most
commonly used method in the UK. It can also be used with a published formula to
predict accurately 30-minute equilibrated urea. The method has not been validated
in patients undergoing haemodiafiltration (HDF). Given the increased use of HDF
across Europe we felt it prudent to assess the utility of the SDF method and
prediction equation in this modality.
Methods
14 patients from 2 renal units were studied. Blood samples were taken at oneminute intervals from the arterial and venous lumens in the first 5 minutes after HDF
had ceased and blood circulation continued. A peripheral sample was taken from the
contralateral arm immediately after HDF had ceased and a 30-minute sample was
taken from the arterial needle. These samples were used to assess the utility of 5minute arterial blood urea and the 30-minute prediction formula respectively.
Results
Blood urea measured from the arterial circuit at 5 minutes correlated closely with the
contralateral sample taken immediately post HDF with no significant difference (6.45
 2.11 vs 6.52  2.19 mmols/litre. p = 0.39). The use of 5-minute arterial blood urea
and prediction formula allowed an accurate prediction of 30-minute urea (R2 = 0.96).
Conclusions
The use of the SDF method with a 5-minute post HDF arterial sample is valid in
patients receiving haemodiafiltration. The previously published prediction formula for
estimating 30-minute urea is also valid using the 5-minute post HDF sample.
Importance of Body Composition and its Relationship to Bone
Mineral Content in Children with Chronic Kidney Disease
Rashid R1, Neill E2, Kirkwood A1, Mak M1, Russell S2, Smith W1, Maxwell H2, Ahmed SF 1
1.
2.
Bone & Endocrine Research Group, Royal Hospital for Sick Children, Glasgow
Renal Unit, Royal Hospital for Sick Children, Glasgow
In a LREC approved observational study, dual energy x-ray absorptiometry (DXA) was used
to assess body composition, defined as lean mass (LM), and fat mass (FM), and to examine its
relationship with bone mineral content (BMC), in 60 children with CKD – 30 children
(22M,8F) with chronic renal insufficiency (CRI) (median age: 11.6 yrs, 10th, 90th centiles: 6.7,
15.8) and 30 children (20M,10F) post-transplantation (Tx) (median age 13.4 yrs (7.8,17.5)).
Median duration post-Tx was 3.4 yrs (1.8,5.4). Body mass index (BMI), LM and FM were
adjusted for height and expressed as BMIHSDS, LM HSDS and FM HSDS. Regional fat
composition was expressed as a percentage of predicted trunk:leg ratio (ppT:L fat ratio).
BMC was measured as total body BMC, adjusted for height age and expressed as percentage
of predicted BMC (ppHBMC). Data were also analysed for differences between sex and
pubertal status.
In the CRI group, median HtSDS was –1.6(-3.1,0.3). Median %calorie and %protein intake
were 95%(84,119) and 100%(93,120). BMI HSDS, LM HSDS and %FM HSDS were 0.9(1.5,2.6), –1.1(-1.8,0.3) and 1.1(0.1,2.4), respectively. ppT:L fat ratio and ppHBMC were
153%(96,186) and 104%(96,114) respectively. There was a significant correlation between
ppHBMC and LM HSDS (r 0.6, p<0.05) but not with %FM HSDS. This correlation was
strongest in boys. Both pre- and post-pubertal children showed an association between
ppHBMC and LMHSDS (r, 0.5, p<0.05).
In the Tx group, median Ht SDS was –1.7 SDS (-3.3,0.1). Median %calorie and %protein
intake were 102% (88,118) and 119% (98,140). BMI HSDS, LMHSDS and %FMHSDS were
1.1(-0.6,2.6), -0.8(-1.8,0.3) and 1.3(0.3,2.5) respectively. The ppT:L fat ratio and ppHBMC
were 158%(103,206) and 92 % (71,108). In boys, there was an association between
ppHtBMC and LMHSDS (r, 0.6, p<0.05) and %FMHSDS (0.6, p<0.05). This was not
observed in girls. The correlation between ppHBMC and LMHSDS was stronger in the
pubertal children than the pre-pubertal group and in both groups, BMI HSDS was
significantly higher than LM HSDS and lower than %FM HSDS (p<0.05). There was no
association between BMC and nutritional intake in either group.
Adjustment for height is crucial when studying body composition and bone health in children
with chronic disease. BMI does not accurately represent body composition in children with
CKD who have relatively high FM and a low LM. FM distribution is centrally located
irrespective of whether these children receive steroids. There is a strong association between
BMC and LM in children with CKD. BMC is significantly lower in the Tx group than in the
CRI group. Interventions that address body composition may prove beneficial for long-term
bone health and cardiovascular health.
Outcomes of a Hepatitis B vaccination audit in the Edinburgh and Borders haemodialysis
population: implications and recommendations for service improvement.
SY Liong, M Ogilvie, J Goddard. Department of Renal Medicine Royal Infirmary of
Edinburgh
Background: The Clinical Standards for Adult Renal Services developed by the Clinical
Standards Board for Scotland and the Scottish Renal Registry recommends that all patients
requiring renal replacement therapy be vaccinated against Hepatitis B as far in advance of
starting RRT as possible. In Lothian and Borders region, vaccination is performed by GPs
after a written request from the renal clinics. Because vaccination is not performed centrally,
the prevalence of hepatitis B immunization within the haemodialysis population and the
adherence to these accepted recommendations are unknown.
Objective: To determine the prevalence of Hepatitis B immunization within the Lothian and
Borders haemodialysis population, to identify barriers and to make recommendations for
service improvement.
Methods: Data collection forms were sent to GPs to obtain information on the vaccination
status, type of vaccine used and dates administered for each of the 221 patients undergoing
haemodialysis in June 2004. The responses were entered into a database and results analysed.
Results: 195 (88.2% response rate) data collection forms were completed. Of these 195
patients, 123 have GP records of vaccination (63.1%) and 66 have no records (33.8%). Of the
remaining six patients, four did not require vaccination and the GPs of the other two patients
were uncertain about their patients’ vaccination status. Only 23 of the 123 patients (18.7%,
and 11.8% of all replies) who have been vaccinated recieved the correct dose (40iu x 3) and
within the correct time frame (at 0,1 and 6 months). However, our results also show that
patients are being vaccinated earlier (in 2002, mean of 1.57 months; 2003, mean of 8 months;
and 2004, mean of 9.5 months prior to commencing haemodialysis).
Conclusions: There is a lack of conformity to the recommended guidelines in respect of the
vaccination of haemodialysis patients against Hepatitis B with the correct doses and within an
acceptable time frame. This audit has resulted in the following internal recommendations.

Currently, GPs are informed by the Renal Unit that their patient is being prepared for
haemodialysis and needs Hepatitis B vaccination. There is no routine follow-up. We
recommend that standard data collection forms indicating administration of vaccination
(with dose and date) be appended to the initial letters to GPs requesting vaccination. The
forms would then be returned to the Renal Unit on completion of the initial course and
entered into the proton database to enable follow-up of patients’ vaccination status.

For patients starting dialysis acutely, we recommend that they receive Hepatitis B
vaccination as soon as possible, administering the first dose at initial presentation to the
Renal Unit with standardized documentation on a similar data collection form, which
would then be sent to their GPs to administer the remaining doses.

Patients identified through the audit who have not received Hepatitis B vaccinations or
have received vaccinations but at the wrong dose or time, should receive proper
vaccination at the right dose and schedule as soon as possible.

Continuing medical education, discussion and dissemination of guidelines, and regular
clinical audit are necessary to improve the prevalence of Hepatitis B immunization in
the haemodialysis population.
For submission to The Scottish Renal Association
Cinacalcet for Hyperparathyroidism in a Renal Transplant Patient
Dr K. Donaldson1, Dr A. Pall1, Prof. S. Fleming2
1. Dept of Renal Medicine, Ninewells Hospital Dundee. 2. Dept of
Pathology, Ninewells Hospital Dundee.
Cinacalcet is a calcimimetic agent that targets the calcium-sensing receptor on the parathyroid
gland. Several studies have established that cinacalcet is effective in reducing parathyroid
hormone levels in dialysis patients who have secondary hyperparathyroidism (SHPT). It also
significantly reduces calcium, phosphate and Ca x P product. Calcimimetics may therefore
provide an alternative to parathyroidectomy in dialysis patients with SHPT especially those
who are unfit for surgery. SHPT may also be seen in patients after renal transplantation.
However clinical experience in the use of cinacalcet in these patients is limited and without
published data.
We present a case report of a renal transplant patient with SHPT treated with cinacalcet.
A 67-year-old woman who developed end stage renal failure in 1996 secondary to
hypertension and renovascular disease received her first renal transplant pre-emptively in
1996. This failed in early 2002 from CAN and she went onto haemodialysis briefly before
undergoing a cadaveric transplant in late 2002. She had a sub-total parathyroidectomy in 1983
for a solitary adenoma. Since 1997 she had been hypercalcaemic and with progressive rise in
PTH levels. In 1999 she was reviewed by the endocrine surgeons and considered not an ideal
candidate for parathyriodectomy due to co-morbidity and previous parathyroid surgery. In
March 2004 the PTH level was 32 pmol/L, serum calcium 2.61 mmol/L, phosphate 0.89
mmol/L and a sestamibi scan revealed an increased uptake in the right upper lobe parathyroid
gland. In September 2004 she underwent transplant biopsy because of a slowly rising serum
creatinine from 150 baseline to 220 umol/L. This revealed calcium deposition in the tubules.
She was therefore started on cinacalcet at 30 mg daily. In the following 4 months the PTH has
fallen from 32 to 16 pmol/L, calcium from 2.86 to 2.16 mmol/L, Ca X PO4 product from 3.36
to 2.46 mmol2/l2. 1-alfacalcidol 0.25mcg daily was started when the serum calcium reached
low reference normal and she continues on cinacalcet at 30 mg daily. Transplant function has
remained stable with serum creatinine at 160 umol/L and we noted no effect on tacrolimus
levels. In this renal transplant with SHPT cinacalcet proved to be effective and safe.
Successful
treatment
of
calciphylaxis
with
cinacalcet:
An
alternative
to
parathyroidectomy?
Velasco N, MacGregor MS, Innes A, Mackay IG
Crosshouse Hospital, Kilmarnock
Abstract
A 49-year-old man with end-stage renal disease developed rapid onset, widespread soft tissue
calcification and typical superficial leg ulcers consistent with calciphylaxis. He had
uncontrolled secondary hyperparathyroidism but was not fit for parathyroidectomy and was
therefore treated with cinacalcet. Rapid biochemical and clinical improvement ensued,
followed by healing of the skin ulcers. The treatment was well tolerated. We speculate that
cinacalcet, in some cases, might replace parathyroidectomy as the first choice therapy for this
serious and frequently lethal condition. We believe this is the first report of treatment of
calciphylaxis with cinacalcet.
Enhanced surveillance of haemolytic uraemic syndrome
microangiopathies (ENSHURE) in Scotland, 2003-2004
and
other
thrombotic
Pollock KGJ, Rae L, Locking ME, Reilly WJ
Health Protection Scotland (HPS), Glasgow, G3 7LN
Haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopaenic purpura (TTP) are
rare disorders characterized by platelet aggregation, micro-thrombi, and resulting tissue
damage. HUS in childhood is one of the most common causes of acute renal failure in
children in the UK. Fatality rates for HUS may be up to 10%. Around 10% of cases
experience chronic renal failure and a further 40% suffer long-term renal impairment,
sometimes many years after illness, and the determinants of long-term outcomes are unclear.
Without current surveillance of HUS and TTP, neither prevalence nor outcomes are well
known in either adults or children.
Co-ordinated by HPS, ENSHURE seeks to identify both health outcomes and existing
management strategies. ENSHURE comprises clinically driven enhanced surveillance of
HUS and TTP and also further investigates the links between these syndromes and factors,
which have been implicated in the etiology of HUS and TTP including infections, vascular
procedures, chemotherapeutic agents and immunosuppressants. Previous surveillance of
childhood HUS in Scotland identified E. coli O157 in over 90% of cases. Enhanced
surveillance is particularly relevant in Scotland, as higher rates of infection with E. coli O157
have consistently been reported, compared with other parts of the UK or Europe, in recent
years. Infection with E. coli O157 is now reported to be one of the major causes of acute
renal failure in children.
ENSHURE seeks to extend current knowledge by monitoring all age groups as well as a
range of clinical presentations of thrombotic microangiopathies. This study provides a range
of data, including epidemiology, demography, clinical details and treatment outcomes (both
short and long term) and explores the familial and social impact of illness. Data for the first
two years of the programme will be presented.
Abstract
Peritoneal Dialysis is commonest method of renal replacement therapy in children
with acute renal failure secondary to Haemolytic Uraemic Syndrome (HUS). In our
institution two methods of peritoneal dialysis catheter insertion are used, operative
surgical insertion under a general anaesthetic and percutaneous insertion under local
anaesthetic at the bedside. The aim of this study was to compare the complication
and survival rates of peritoneal dialysis catheters inserted using the two different
methods, in infants and children with HUS.
A fifteen year retrospective study was undertaken of all patients diagnosed with HUS.
210 cases were identified, of whom 146 required peritoneal dialysis. The initial
catheter was inserted surgically in 36 patients and percutaneously in 110 patients.
Catheter failure occurred in 11/36 (30.6%) surgical catheters and 71/110 (64.5%)
percutaneous catheters (p<0.0005). Duration of use was significantly longer in
surgically placed catheters, 7 days compared to 4 days (p<0.0008).
Surgical insertion of acute peritoneal dialysis catheters results in significantly less
failures and a longer duration of use compared to percutaneously inserted catheters.
We therefore advocate the use of surgically placed catheters for peritoneal dialysis in
children with Haemolytic Uraemic Syndrome requiring dialysis.
Three years experience with a biopsy database
M Andrews, G Stewart, S Fleming, A Petrie
Ninewells Hospital, Dundee
Introduction: A renal biopsy database provides a means of auditing safety, competence,
biopsy practice, clinical presentation and incidence of specific renal diseases. We present data
on all native and transplant biopsies performed in Dundee in the last 3 years.
Methods: All renal biopsies are recorded at the time of the procedure with details on
indication, BP, Immunology, proteinuria, and technical data. Biopsies are reviewed with a
renal pathologist every 2 weeks. At this time pathological and complication data are added to
the paper record of the procedure and the complete data set is then entered on the electronic
database.
Results: 252 biopsies, (188 native, 64 transplant) were performed between January 2002 and
January 2005.
With regard to safety; 8 patients (3.2%) had macroscopic haematuria, 9 (3.6%) had pain
requiring more than paracetamol and 2 (0.8%) required transfusion of packed cells.
Cortical tissue was obtained in 95.6% of biopsy attempts. 80.5% of biopsy cores were
histologicaly adequate, (> 6 glomeruli), and 90.1% were clinically adequate to make a
diagnosis.
Indications for native biopsy were; ARF ?cause 26 (14.2%), CRF ?cause 14 (7.7%), nephrotic
proteinuria 21 (11.5%), non-nephrotic proteinuria, microscopic haematuria and normal
creatinine 56 (30.6%), non-nephrotic proteinuria, microscopic haematuria and raised
creatinine 40(21.9%), isolated non-nephrotic proteinuria 19 (10.4%), isolated microscopic
haematuria 7(3.8%).
Conclusions: This biopsy database provides valuable information on safety of practice and
training, facilitating regular audit. Linkage with a clinical database and other centres would
significantly extend the scope of its use
AL amyloidosis: Glasgow Royal Infirmary Experience
Nicola Joss, Jonathan Fox
Renal Unit, Glasgow Royal Infirmary, Glasgow
AL amyloidosis is a rare disorder associated with a poor outcome. We have analysed data of
all patients diagnosed by renal biopsy over a 15-year period at Glasgow Royal Infirmary.
Twenty-six patients were identified (69% male). At diagnosis, the mean age was 69 years,
median serum creatinine 121 μmol/l, ECC 41 ml/min, albuminuria 3.78 g/24h, mean serum
albumin 26 g/l and BP 121/69 mmHg. The median rate of progression of renal failure of the
19 patients who survived more than 6 months was 1.29 ml/min/month. Fourteen patients had
a serum paraprotein detected, (IgGλ 4, IgAλ 3, IgMλ 1, λ light chains 4, IgM 1, IgG 1). Of
the 12 patients without a paraprotein in their serum, a urine paraprotein was detected in 11
cases, (λ 10,  1). One patient had no paraprotein in either urine or serum. A bone marrow
examination was performed in 23 patients, the proportion of plasma cells was less than 5% in
9, 5-10% in 7, 10-30% in 5 and greater than 30% in 2.
Twenty patients received treatment; 18 had melphalan and prednisolone with a mean number
of cycles of 6 (range 1-14). One patient received idarubicin and dexamethasone and 1 patient
received high dose dexamethasone. The 6 patients who received no treatment were
significantly older but their renal function did not differ to those who received treatment. The
median survival was 8.8 months and there was no difference in survival between those with
myeloma and those without. Five patients (19%) survived more than 5 years (2 had
myeloma). These patients were significantly younger (60 v 71 years) and all received
treatment with melphalan and prednisolone with the number of courses ranging from 7 to 14.
Seven patients commenced renal replacement therapy with a median survival on dialysis of
31 months.
In conclusion, our patients with AL amyloidosis usually present with mild renal impairment
and nephrotic syndrome but renal failure tended to progress quickly. Despite 77% of patients
being deemed suitable to start chemotherapy, survival was poor. The five patients who
survived more than 5 years tended to be younger and had more courses of treatment than
average.
No funding or conflicts of interest
Hyperkalaemia causing profound bradycardia
Keira Noble, Chris Isles
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries, DG1 4AP
Two elderly patients presented with profound bradycardia. Both were taking ACE inhibitors.
One had diarrhoea and the other recently started spironolactone. The first patient’s ECG
showed regular broad QRS complexes with no P waves. She was paced without
improvement. The second patient’s ECG showed irregular broad QRS complexes and absent
atrial activity, consistent with slow atrial fibrillation. Initial treatment was with atropine and
an external pacemaker. Results of emergency biochemistry then showed serum potassium
levels of 9.4 and 7.7 mmol/l respectively. The heart rate in both cases responded to
intravenous calcium chloride. These two ECGs are examples of hyperkalaemia causing
profound bradycardia, mimicking complete heart block. The clue to the correct diagnosis is
the broad complex with absence of P waves. True second and third degree AV block have
been described in hyperkalaemia but are extremely uncommon because the P wave usually
disappears before such advanced AV block occurs.
Post transplant lymphoproliferative disease successfully treated with rituximab: case report and review of literature
Katie Lake, Sue Robertson, Chris Isles
Renal Unit, Dumfries and Galloway Royal Infirmary, Dumfries, DG1 4AP
A thirty eight year old woman noticed a lump below the medial end of her transplant wound,
eighteen months after a second cadaveric graft. Her underlying diagnosis was focal
segmental glomerulosclerosis, early recurrence of which had led to the loss of her first graft.
Her second transplant was perfectly matched, with no rejection episodes. Serum creatinine
was 116 µmol/l while taking tacrolimus 5 mg daily, mycophenolate 1000 mg daily and
prednisolone 5 mg daily. Imaging my ultrasound and CTR showed a 6 cm soft tissue mass
inferior to the transplanted kidney, encircling the femoral vessels. There were no other sites
involved. A diagnosis of monoclonal polymorphic high grade non Hodgkin’s lymphoma was
made by CT guided biopsy. Immunohistochemistry showed cells positive for CD20, CD79a
and CD 30 antigens. An Epstein-Barr early response assay, (EBER), which detects viral RNA
in the infected cells, was strongly positive for Epstein-Barr virus. Withdrawal of tacrolimus
and mycophenolate was not associated with any loss of graft function (serum creatinine 123
µmol 1-1) but led to only a small reduction in tumour size from 6 cm to 5.3 cm. This was
followed by treatment with rituximab, a chimaeric anti CD20 monoclonal antibody, by once
weekly infusion for four weeks. The treatment was well tolerated and led to a significant
further reduction in tumour size to 2 cm. Her subsequent course has been complicated by
recurrence of FSGS but not of her lymphoma. When last seen at the clinic 52 months after
her initial presentation serum creatinine was 102 µmol l1 while taking prednisolone only. The
lymphoma was no longer visible on ultrasound. The literature on the use of rituximab for
PTLD will be reviewed.
Deep seated bony infection related to haemodialysis catheters
Patrick B Mark, Siobhan K McManus, Colin C Geddes, Margaret A McMillan
Renal Unit, Western Infirmary, Dumbarton Road, Glasgow
Catheter related sepsis is a common problem in haemodialysis patients. We present a series of
cases with enduring deep seated infection related to dialysis access catheters, illustrating the
potentially catastrophic nature of this complication. Based on these cases, we emphasize the
need for rigorous investigation and prolonged treatment of patients undergoing haemodialysis
through temporary access who present with sepsis of an unknown aetiology.
A review of the literature, with evidence for best practise where available, for management of
patients with infective complications of haemodialysis access will be presented in our
discussion of these cases.
TRANSPLANT RENAL ARTERY STENOSIS
SK McManus, N Ritchie, S Koteeswaran, G Baxter & C Geddes
Western Infirmary, Glasgow
Transplant renal artery stenosis (TRAS) is a potentially remediable cause of post-transplant
refractory hypertension, graft dysfunction and allograft loss occurring in 1-23% of renal
transplant recipients. Treatment options include angioplasty with or without stent insertion
and surgical revision. These are not without risk. The lack of randomised controlled clinical
trials means that optimal treatment is not yet established.
Method
We carried out a retrospective analysis of the clinical outcomes of forty three patients
diagnosed with transplant renal artery stenosis between 1990-2003 and compared these with a
control group without TRAS (n=23). The diagnosis was based on a transplant renal artery
velocity greater than 2.5ms-1 or arteriography. Thirty four had arteriography; angioplasty +/stenting was performed in twenty seven.
Results
The majority of patients (60.5%) presented within a year of receiving a renal allograft.
Mean systolic BP was improved by intervention (pre-intervention SBP163mmHg vs
145mmHg 3 months post intervention (p=0.001)). This difference was maintained after 5
years (SBP 137mmHg; p=0.017). By comparison, there was no change in the BP in the no
intervention group over the same period. There was no difference in the number of antihypertensive drugs used in these groups.
Comparison of means of estimated creatinine clearance (ECC) before and after intervention
showed no difference. Analysis of time series data using ECC gradients showed an initial
trend towards improvement (ECC gradient in 3 months post intervention +16.72 ml/min/yr)
which was then lost after 3 months (ECC gradient 3 to 12 months -9.14ml/min/yr and 1 to 5
years –2.11 ml/min/yr).
Analysis of slopes from the non-intervention and the control groups showed a trend towards
improvement in the first 12 months followed by gradual deterioration in the control group
over 3 years (-5.5ml/min/yr) and maintenance of renal function in the TRAS no intervention
group (+0.17ml/min/yr), P=0.016. Thus the patients with conservatively treated TRAS did
slightly better than those in our control group.
Doppler ultrasound parameters (transplant renal artery velocity , peak systolic velocity, end
diastolic velocity, resistive index & pulsatility index) were not statistically significantly
different in the intervention and no intervention groups (all p>0.3) and did not correlate with
clinical outcome.
Conclusions
Angioplasty +/- stenting improved blood pressure control up to 5 years after intervention.
Contrary to suggestions in published literature, our data would suggest that conservative
management of some patients with TRAS and stable renal function and blood pressure is
appropriate.
TITLE:
Non-invasive assessments of aortic structure and function in End Stage Renal
Disease
AUTHORS' NAMES:
Arthur Doyle , Nicola Johnston, John, Patrick Mark, John MC Connell, Henry Dargie,
Alan Jardine, Neal Padmanabhan
Abstract
Background
Arterial stiffness is associated with adverse cardiovascular outcomes, particularly in
end -stage renal disease. One mechanism linking arterial stiffness with
cardiovascular events may be the effect of changes in pressure wave reflection on
ventricular ejection and coronary perfusion during diastole. We report a comparison
between established pulse wave analysis techniques along with novel MRI studies to
describe aortic elastic properties and blood flow.
Methods and Results
10 Patients with End Stage Renal Disease(ESRD) and 10 control subjects were
studied. Transverse Images and velocity maps of the ascending aorta were obtained
by MRI along with assessments of brachial blood pressure and estimated central and
measured carotid pressure waveforms by sphygmocor. Aortic Distensibility(D) was
calculated from both peripheral and estimated central pulse pressure(PP).
Using brachial PP, ESRD patients had reduced D (0.001965mmHg-1) compared to
the control (0.004381mmHg-1). p = 0.0088. Observations of aortic blood velocity
revealed an early drop in systolic blood velocity coinciding with the reflected arterial
pressure wave in patients with ESRF.
Conclusions
CMRI is a sensitive method of estimating aortic distensibility directly. CMRI also
demonstrates the functional effect of reduced D on flow in the aorta, providing
insight into the pathophysiology of ventriculo-vascular interaction. Pressure
waveforms obtained by applanation tonometry and mathematical transfer function
appeared to correlate with observed changes in aortic blood flow measured by MRI.
Using non-invasive methods we have demonstrated a marked reduction in D and,
simultaneously, the extent of reduction in aortic blood flow caused by pressure wave
reflection in patients with ESRD.