Table 1.
Exercise-induced pulmonary vascular dysfunction in an ISCU mut/mut individual
| Hemodynamic index | Rest | Peak exercise |
|---|---|---|
| RAP (mmHg) | 5 | 12 |
| Mean PAP (mmHg) | 21 | 31 |
| PCWP (mmHg) | 7 | 10 |
| CO (l/min) | 6.5 | 11 |
| PVR (dynes s/cm5) | 160 | 135 (normal < 80 for persons < 50 years) |
| ΔPAP/ΔCO (mmHg/l/min) | 2.2 (normal < 2 for persons < 50 years) | |
| ΔTPG/ΔPCWP | 2.3 (normal < 1) |
Advanced cardiopulmonary exercise testing was performed on a woman with homozygous ISCU mutations. At rest, she displayed normal right atrial pressure (RAP) and pulmonary capillary wedge pressure (PCWP) but a mean pulmonary arterial pressure (PAP) at the upper limit of normal. During exercise, RAP and mean PAP were elevated but with PCWP remaining normal. Most importantly, abnormal indices of pulmonary vascular resistance (PVR) were evident (including lack of an appropriate decrease in PVR during exercise and increased ratios of ΔPAP/ΔCO and ΔTPG/ΔPCWP), thus fulfilling criteria for “exercise-induced PAH” that do not rely solely upon changes in mean PAP alone (Tolle et al, 2008b; Lewis, 2010).