Your heart may be at risk from standard hemodialysis (HD)—three times a week for 3–4 hours at a time—even if you never had a heart problem before. But, the risk you may face is not just the run-of-the-mill one most Americans have (plaque in the arteries). Instead, standard HD can starve your heart of oxygen. In time, this problem, called myocardial stunning, can lead to heart failure. Take steps to protect your heart!

How standard HD can starve your heart

While you go about your day, your heart pumps blood through your 60,000 miles or so of blood vessels. During an HD treatment, a blood pump on the dialysis machine also pushes your blood through the tubing and dialyzer. But, your blood may pass through the tubing as fast as half a liter per minute.* Echocardiograms¹ and PET scans² show that blood flow to the heart drops during HD. And, with less blood, less oxygen can reach your heart.

^* This fast blood flow is why it’s vital to never cover your access during a treatment. If the venous needle came out or the tubing pulled apart at standard HD, you could lose all of your blood in 6 minutes!

You may think that less blood reaches your heart because it is going through the machine instead. This is only partly true. What matters more is that dialysis removes excess fluid that has built up in your blood since your last treatment. The more you gain, the more the dialysis must remove.

What’s UFR got to do with it?

Fluid removal at dialysis is called ultrafiltration, or UF. The ultrafiltration rate, or UFR, in mLs per hour per kilo of body weight is key. A 7-year study at Harvard of 1,846 people on dialysis found that:³

• Those with UFRs greater than 13 mL/h/Kg were the most likely to die.
• Those with UFRs between 10 and 13 mL/h/Kg had higher rates of heart failure.
• Those who lived the longest had UFRs less than 10 mL/h/Kg.

If your dialysis time is short (and you have just three treatments a week), a lot of fluid will be removed. Your UFR may need to be higher than 10. This will cause a sharp drop in your blood volume—and in your blood pressure and blood flow. With less blood pressure and flow, less blood will reach the coronary arteries that bring blood to your heart.

Your heart muscle needs oxygen to work. The blood flow through your coronary arteries brings this oxygen to your heart muscle. If your heart muscle has less blood flow, it has less oxygen. This fall in blood flow and oxygen ‘shocks’ (or stuns) the heart muscle. If this were to happen just once, your heart would recover. But, since the damage occurs over and over, it adds up. The heart’s largest pumping chamber (the left ventricle) is stressed—and may fail.¹ This process even happens in children.⁴ In one study, 64% of people on dialysis had a lot of cardiac stunning.5

You can protect your heart

It’s scary to know that your heart muscle may be ‘zapped’ while you dialyze. But, the good news is that there is a lot you can do to protect yourself—even on standard in-center HD:

• Gain less fluid. If you don’t gain as much, there is less to remove and the UFR can be lower. Eating less salt and sugar can help reduce thirst. Talk to others on dialysis or your dietitian for tips about reducing thirst.
• Do longer treatments. If you gain a lot of fluid, adding more treatment time means that you can remove it without raising your UFR to a high rate. Some clinics will let you come in for an extra treatment. Or, talk to your doctor about running longer.
• Ask your doctor about cooler dialysate. Cold dialysate (less than 35.5°C) has been linked with longer life and less heart damage.⁶ Most people can’t stand being that cold during a treatment. But, every little bit counts. One small study found that having the dialysate as cool as patients could handle below 37°C helped the heart.⁷
• Use ultrapure water. You don’t have much control over the quality of the water used to make HD dialysate in a clinic. But some clinics do use “ultrapure” water. This matters, because the purer the water, the fewer the germs and toxic cell walls (endotoxin) in the dialysate that can get into your blood. One study found a link between higher levels of endotoxin and more heart damage.⁸
• Get the best access you can. A fistula that can handle a lot of blood flow can help ensure that your heart gets enough blood, even during a treatment. In a study, fistulas that had flows of over 1 liter per minute were best.⁹
• Switch to peritoneal dialysis (PD). PD does not speed your blood through a filter at half a liter per minute. In a small study (just 10 patients), PD was not found to cause cardiac stunning.¹⁰
• Switch to short daily or nocturnal HD. A study looked at 46 people who did standard in-center HD, short daily HD in a clinic or at home, and nocturnal HD at home. The longer and/or more often HD was done—the less it harmed the heart. Nocturnal HD can be done in-center or at home.¹¹

Conclusion

Be gentle to your heart when you are on dialysis! Gain less fluid or remove it more slowly to avoid the myocardial stunning that can lead to heart failure.

References

1. McIntyre CW, Burton JO, Selby NM, Leccisotti L, Korsheed S, Baker CS, Camici PG. Hemodialysis-induced cardiac dysfunction is associated with an acute reduction in global and segmental myocardial blood flow. Clin J Am Soc Nephrol. 2008 Jan;3(1):19–26. Epub 2007 Nov 14.
2. Dasselaar JJ, Slart RH, Knip M, Pruim J, Tio RA, McIntyre CW, de Jong PE, Franssen CF. Haemodialysis is associated with a pronounced fall in myocardial perfusion. Nephrol Dial Transplant. 2009 Feb;24(2):604–10. Epub 2008 Sep 4.
3. Flythe JE, Kimmel SE, Brunelli SM. Rapid fluid removal during dialysis is associated with cardiovascular morbidity and mortality. Kidney International. 2011; 79, 250–257; doi:10.1038/ki.2010.383; published online 6 October 2010.
4. Hothi DK, Rees L, Marek J, Burton J, McIntyre CW. Pediatric myocardial stunning underscores the cardiac toxicity of conventional hemodialysis treatments. Clin J Am Soc Nephrol. 2009 Apr;4(4):790–7. Epub 2009 Apr 1.
5. Burton JO, Jefferies HJ, Selby NM, McIntyre CW. Hemodialysis-induced cardiac injury: determinants and associated outcomes. Clin J Am Soc Nephrol. 2009 May;4(5):914–20. Epub 2009 Apr 8.
6. Heng-Jung Hsu, Chiung-Hui Yen, Kuang-Hung Hsu, Chin-Chan Lee, Shu-Ju Chang, I-Wen Wu, Chiao-Yin Sun, Chia-Chi Chou, Chen-Chao Yu, Ming-Fang Hsieh, Chun-Yu Chen, Chiao-Ying Hsu, Cheng-Hao Weng, Chi-Jen Tsai and Mai-Szu Wu. Association between cold dialysis and cardiovascular survival in hemodialysis patients. Nephrol Dial Transplant. 2012 Jun;27(6):2457–64. Epub 2011 Nov 5.
7. Jefferies HJ, Burton JO, McIntyre CW. Individualised dialysate temperature improves intradialytic haemodynamics and abrogates haemodialysis-induced myocardial stunning, without compromising tolerability. Blood Purif. 2011;32(1):63–8. Epub 2011 Feb 24.
8. McIntyre CW, Harrison LE, Eldehni MT, Jefferies HJ, Szeto CC, John SG, Sigrist MK, Burton JO, Hothi D, Korsheed S, Owen PJ, Lai KB, Li PK. Circulating endotoxemia: a novel factor in systemic inflammation and cardiovascular disease in chronic kidney disease. Clin J Am Soc Nephrol. 2011 Jan;6(1):133–41. Epub 2010 Sep 28.
9. Korsheed S, Burton JO, McIntyre CW. Higher arteriovenous fistulae blood flows are associated with a lower level of dialysis-induced cardiac injury. Hemodial Int. 2009 Oct;13(4):505–11. Epub 2009 Sep 16.
10. Selby NM, McIntyre CW. Peritoneal dialysis is not associated with myocardial stunning. Perit Dial Int. 2011 Jan-Feb;31(1):27–33. Epub 2010 Jun 3.
11. Jefferies HJ, Virk B, Schiller B, Moran J, McIntyre CW. Frequent hemodialysis schedules are associated with reduced levels of dialysis-induced cardiac injury (myocardial stunning). Clin J Am Soc Nephrol. 2011 Jun;6(6):1326–32. Epub 2011 May 19.

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