Hi. Thank you for sharing your experience with the community. It’s great that your lungs are in good condition following your pulmonary workup. What you're describing—oxygen levels dropping and your pulse increasing after relaxing or standing—could indeed be related to your heart, especially with a history of heart failure. When you stand, your body has to adjust to the change in position, and your heart may be working harder to pump blood effectively. This can sometimes lead to symptoms like shortness of breath and anxiety. Have you had a chance to discuss this pattern with your cardiologist? John. community moderator.