10.8 Chronic Kidney Disease and the Dialysis-Dependent Cardiac Patient

Staging and the Central Epidemiologic Fact

Test-plan item II.E.2 rests on one statistic that reframes everything: a patient with stage G3–G4 chronic kidney disease (CKD) is far more likely to die of cardiovascular disease than to reach dialysis. Cardiovascular mortality is roughly 10–30 times higher in dialysis patients than in the age-matched general population, and about half of all deaths on dialysis are cardiovascular. CKD is not a renal comorbidity in a cardiac patient — it is a coronary risk equivalent that also changes every drug dose you give.

CKD is defined as abnormalities of kidney structure or function present for more than 3 months, and is staged in two dimensions.

Both axes carry independent cardiovascular risk: a G3a/A3 patient is at higher risk than a G3b/A1 patient. Albuminuria is a marker of systemic endothelial dysfunction, which is why it tracks with cardiovascular events rather than just renal ones.

Uremic Cardiovascular Disease

• Accelerated atherosclerosis driven by inflammation, oxidative stress, hyperphosphatemia, dyslipidemia and uremic toxins. Presentations are more often silent or atypical because of diabetic neuropathy and blunted symptom reporting.
• Vascular and valvular calcification. CKD produces medial calcification (Monckeberg sclerosis) in addition to intimal plaque, producing stiff, non-compressible vessels, a wide pulse pressure, falsely elevated ankle-brachial indices, and accelerated calcific aortic stenosis — dialysis patients develop severe AS roughly a decade earlier than the general population.
• Left ventricular hypertrophy from pressure load (hypertension, aortic stenosis, arterial stiffness) and volume load (anemia, arteriovenous fistula flow, salt and water retention). LVH plus small-vessel disease produces diastolic dysfunction, subendocardial ischemia with normal coronaries, and a heart that tolerates neither volume excess nor rapid volume removal.
• Uremic pericarditis. A pericardial friction rub in a patient with a BUN typically above 60 mg/dL. Its ECG is characteristically atypical — often without the diffuse concave ST elevation and PR depression of viral pericarditis — because the uremic inflammatory process is confined to the pericardium and does not involve the epicardial myocardium. It is a distinct indication for urgent, intensified (often daily, heparin-free) dialysis, and it can progress to tamponade. Dialysis-associated pericarditis in an already-dialyzed patient signals inadequate dialysis dose.
• CKD–mineral and bone disorder (CKD-MBD): phosphate retention, low calcitriol, secondary hyperparathyroidism, and in severe cases calciphylaxis — painful violaceous necrotic skin lesions with very high mortality.
• Uremic platelet dysfunction producing a bleeding tendency at the access site, GI tract and pericardium despite a normal platelet count and INR; desmopressin, cryoprecipitate, conjugated estrogens and dialysis are the interventions.

Running a Dialysis Patient on a Cardiac Unit

Intradialytic hypotension complicates 20–30% of hemodialysis sessions and repeatedly produces myocardial stunning — transient regional wall motion abnormalities that, over months, become fixed and drive the cardiomyopathy of dialysis. Ultrafiltration rates above roughly 13 mL/kg/h are associated with excess mortality. The nurse's contributions are concrete: hold antihypertensives before dialysis when ordered, do not schedule an unnecessary sedating medication before a session, report symptomatic hypotension and cramping, and question a dry weight that the patient cannot tolerate.

Dry weight and interdialytic weight gain. Dry weight is the post-dialysis weight at which the patient is euvolemic without hypotension. Interdialytic weight gain is targeted below roughly 4–4.5% of body weight (about 2–3 kg over a two-day interval). Weigh the patient before and after every session on the same scale and report gains outside that range — they predict pulmonary edema, hypertension and LVH.

Potassium timing. Serum potassium is at its lowest immediately after a session and climbs across the interdialytic interval, peaking before the next one. The Monday morning arrest after a long weekend interval is the classic pattern. Draw potassium and check the ECG when a dialysis patient arrives, and interpret any level in relation to the last session.

Access rules — non-negotiable nursing content:

• On the fistula or graft arm: no blood pressure cuff, no venipuncture, no IV catheter, no PICC, no tourniquet, no restraints, no lying on the arm, no constricting clothing. Post it at the bedside.
• Assess thrill by palpation and bruit by auscultation at least every shift and after any hypotensive episode. A newly absent thrill is an emergency — the access has clotted and needs immediate intervention.
• Watch for steal syndrome (cold, pale, painful, numb hand distal to the access) and for high-output heart failure from a very high-flow fistula.
• Post-dialysis needle sites bleed; hold pressure without occluding the access, and remember uremic platelet dysfunction plus the heparin used during the session.
• Tunneled dialysis catheters are accessed only by trained staff using strict aseptic technique, are locked with heparin or citrate, and are not used for routine blood draws or infusions without a specific order.
• Vein preservation: in any patient with advanced CKD who is not yet on dialysis, avoid subclavian lines (central venous stenosis destroys future access options) and avoid PICCs entirely. Use the back of the hand for peripheral IVs and protect the non-dominant forearm.

Dialysis and drug levels. Many cardiac drugs are removed by dialysis and should be given after the session — a chronically under-recognized nursing failure. Water-soluble, low-protein-bound, low-volume-of-distribution drugs are dialyzed. Atenolol, sotalol, metoprolol (partially), lisinopril, enalapril, gabapentin, and many antibiotics are removed; carvedilol, amiodarone, digoxin (large volume of distribution — dialysis does not meaningfully remove it) and warfarin are not.

Renal Dose Adjustment of Cardiac Drugs

This table is high-yield because the nurse is the last checkpoint before the drug is given.

Contrast in the CKD patient versus the dialysis patient. In a patient with advanced CKD not yet on dialysis, residual renal function is precious and every contrast exposure risks pushing them onto dialysis permanently — this is where hydration, contrast minimization and staged procedures matter most. In a patient already anuric and dialysis-dependent, there is no residual function to lose, so contrast can be given when clinically indicated; a dialysis session is scheduled for convenience and volume management, not as urgent prophylaxis, because prophylactic dialysis does not prevent contrast injury.

Anemia, Mineral Metabolism and the Binder Trap

Anemia of CKD results from erythropoietin deficiency, functional iron deficiency, uremic marrow suppression and blood loss in the dialysis circuit. It aggravates angina, LVH and heart failure. Iron is repleted when transferrin saturation is under 30% and ferritin is under 500 ng/mL, usually with IV iron in dialysis patients. Erythropoiesis-stimulating agents (ESAs) are targeted to a hemoglobin of roughly 10–11 g/dL and never normalized — trials that pushed hemoglobin toward 13–13.5 g/dL showed increased stroke, thrombosis, access loss and death. Transfusion is minimized in transplant candidates to avoid HLA sensitization.

Phosphate binders — calcium acetate, sevelamer, lanthanum, ferric citrate, sucroferric oxyhydroxide — must be given with meals to bind dietary phosphate; a binder given between meals does nothing. The nursing trap is the drug-drug interaction: binders chelate other oral agents. Separate levothyroxine by at least 4 hours; sevelamer reduces absorption of ciprofloxacin and can affect mycophenolate; calcium-containing binders bind tetracyclines and quinolones; binders can reduce digoxin and warfarin absorption. Administration timing is a nursing decision that determines whether the cardiac drug works.

Cardiorenal Drug Initiation: The Expected Creatinine Rise

When an ACE inhibitor, ARB, sacubitril-valsartan, mineralocorticoid receptor antagonist, or SGLT2 inhibitor is started or up-titrated in a cardiac patient, creatinine rises and eGFR dips. This is hemodynamic — efferent arteriolar dilation for RAAS inhibitors, restored tubuloglomerular feedback for SGLT2 inhibitors — and it is the fingerprint of the drug working, not of kidney injury. Long-term renal and cardiovascular outcomes are better in patients who tolerate the dip.

The rules:

• A creatinine rise up to 30% (or an eGFR fall up to about 30%) that stabilizes within 2–4 weeks is expected and should not trigger discontinuation.
• A rise above 30%, a rise that keeps climbing, or hyperkalemia above 5.5 mEq/L that does not respond to dietary change, a potassium binder, or diuretic adjustment prompts dose reduction and a search for volume depletion, NSAIDs, or renal artery stenosis.
• SGLT2 inhibitors are initiated down to an eGFR of about 20 mL/min/1.73 m2 and continued until dialysis; the initial "eGFR dip" is expected and reverses on withdrawal.
• Overdiuresis is the most common reversible cause of a rise beyond expectation — reassess volume status before blaming the drug.

Transplant and access planning belong in the nursing conversation early. Cardiac evaluation is a gatekeeper for kidney transplant listing, and an arteriovenous fistula needs to be created months before it is needed, which is why vein preservation on the day of a cardiac admission has consequences years later.