Is This Sinus?

HPI: 50 y/o male with hx of COPD, heroin use, and recently diagnosed cor pulmonale presents with 3 weeks of lower extremity edema. No chest pain, shortness of breath, or palpitations. An EKG is obtained in the emergency department.

Question: 

• What does this EKG tell you about the etiology of this patient’s lower extremity edema?
  
• Is this EKG in sinus rhythm?