Exercise intolerance is a common finding in mitochondrial diseases, including Kearns-Sayre syndrome (KSS), characterised by progressive external ophthalmoplegia, cardiac conduction defects and atypical pigmentary degeneration of the retina. Exercise studies were performed in a 32 year old woman with KSS who had received an atrio-ventricular sequential pacemaker because of continuing breathlessness, having presented with complete heart block requiring a fixed rate demand pacemaker 6 years earlier. Minute ventilation, oxygen consumption, and carbon dioxide production were measured at different workloads on 3 consecutive days by collecting expired air. Compared to controls, after exercise at a subanaerobic workload, heart rate and ventilation were exaggerated relative to both oxygen consumption and carbon dioxide production. The findings are consistent with the hypothesis that, in mitochondrial disorders, impaired oxidative phosphorylation leads to uncoupling of cardiac ouput and ventilation relative to muscle metabolic rate. © Pearson Professional 1996.

Item Type:	Refereed Article
Research Division:	Medical and Health Sciences
Research Group:	Clinical Sciences
Research Field:	Medical Genetics (excl. Cancer Genetics)
Objective Division:	Health
Objective Group:	Other Health
Objective Field:	Health not elsewhere classified
Author:	Nicol, SC (Associate Professor Stewart Nicol)
ID Code:	7944
Year Published:	1996
Deposited By:	Anatomy and Physiology
Deposited On:	1996-08-01
Last Modified:	2011-08-19
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