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Hemodialysis Induced Cardiac Injury in Chronic Renal Dysfunction. Reference: McIntyre CW. Haemodialysis -induced myocardial stunning in chronic kidney disease – A new aspect of cardiovascular disease. Blood Purif . 2010;29:105–110.
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Hemodialysis Induced Cardiac Injury in Chronic Renal Dysfunction Reference: McIntyre CW. Haemodialysis-induced myocardial stunning in chronic kidney disease – A new aspect of cardiovascular disease. Blood Purif. 2010;29:105–110.
Cardiovascular disease in the hemodialysis population continues to contribute to morbidity and mortality. • A transient myocardial ischemia may lead to left ventricular dysfunction (LVD). • As a result, hemodialytic insult may lead to altered functions in organ systems driving an even wider range of pathophysiological processes. • Hardening of the arteries is the most frequent cause of heart disease in dialysis patients. • This results in sudden cardiac arrest and heart failure. • Prolonged dysfunction leads to a condition called as myocardial stunning.
Myocardial Ischemic Potential in Hemodialytic Patients • Hemodialytic (HD) patients are prone to myocardial ischemia. • Myocardial stunning results from markedly reduced coronary fl ow in the heart tissues. • Hence, there is a demand to increased blood fl ow to the myocardium. • Hardening of the arterial walls and narrowing of the inner channel of the artery have an adverse effect on myocardial perfusion and reduces the ischemic threshold. • Blood pressure frequently remains inadequately controlled in a high proportion of HD patients because of their fluctuating fluid status.
Dialysis-Induced Ischemia and Myocardial Stunning • For dialysis-induced ischemia, results were drawn by using the data from ECG-based studies. In a study of 70 cohorts, myocardial stunning was assessed to evaluate extent of HD- induced cardiac injury. • It was manifested by development and recovery of regional wall motion abnormality (RWMA). • A HD-induced myocardial stunning occurred in two-thirds of patients. • Cardiac troponins (cTnT) are often elevated in dialysis patients. • This leads to reduced myocardial perfusion and increase in microcirculatory stress.
Hemodynamic Stability • There is a greater risk of hemodynamic instability in HD patients. • In one of the studies, the dialysate temperature was reduced from 37°C to 35°C. • The trials consisting of small number of patients were relatively short-term. • There was a signifi cant number of new RWMAs occurring during standard dialysis. • By improving mean blood pressure and reducing intradialytic hypotension (IDH) episodes with either biofeedback dialysis (BFD) or reduced-temperature dialysis, a signifi cant reduction in the number of new • RWMAs was observed.
Role of Large-Vessel Coronary Artery Disease in Dialysis-Induced Myocardial Stunning • Myocardial blood fl ow was studied in patients with coronary angiography. • These patients still exhibited myocardial ischemic response to HD. • Secondly, patients with uremic cardiovascular disturbances were assessed. • The dialysis treatments were characterized by particularly large ultrafi ltration requirements and signifi cant relative dialysis-induced hypotension.
Long-Term Consequences of Recurrent HD-Induced Ischemic Injury • Long-term follow-up of HD patients with dialysis based echocardiography to identify those suffering from HD- induced cardiac injury revealed signifi cant effects on cardiac structure, function and patient survival. • Those patients who did not develop HD-induced myocardial stunning cardiac injury, by 1-year follow-up no reduction in overall LV ejection and 100% survival was observed. • Another group who developed HD induced myocardial stunning, 28% patients died. After 1 year follow-up of patients who survived, showed reduction in overall LV ejection by around 10%. • Increased left atrial volume (LAV), which is an indicator of chronic diastolic dysfunction, is independent marker of cardiovascular risk. • Left atrial volume indexed to height (LAVI) was a better predictor of mortality than LV mass index, but both were displaced as independent determinants of mortality with the addition of myocardial stunning. • The LAVI significantly correlated with number of RWMAs and chronological age.
Potential Effects of HemodynamicPerturbation on Other Vascular Beds • There are several pathologies described in dialysis patients including silent cerebral infarct, cerebral atrophy and leukoaraiosis. • The gut is another potential aspect other than brain. • Translocation of endotoxin across gut wall is associated with proinflammatory stimulus. • The elevated endotoxin level correlate with intradialytic instability, systemic inflammation and cTnT levels in patients with dialysis-induced myocardial stunning.
Conclusion • The procedure of HD exerts a signifi cant acute stress upon the cardiovascular system. • Cardiovascular disease remains the primary risk for poor health outcomes and high mortality in patients undergoing maintenance dialysis. • Enhanced understanding of dialysis-induced cardiac injury may provide novel therapeutic targets to reduce currently excessive rates of cardiovascular morbidity and mortality. • Episodes of ischemia may potentially have a role in the development of cardiac failure and as a trigger for • arrhythmias.
