Hello and thank you for using HCM.I carefully read your question and I understand your concern. I will try to explain you something and give you my opinion. Sob, difficulties in breathing deeply might have different causes like pulmonar, cardiac ect. Asthma is a strong cause of dispnea.Lungs might be clear but the person might experience bronchial spasm that lead to asthmatic crises. Another reason might be cardiac.Carsiac insuficiensy, meaning a reduced heart function might lead to sob.if your wife has replaced a valve, than valvar situation should be ok.Pacemaker is like a battery and it improves heart function, so it doesn t lead to dispnea. Even though, as we are dealing whith a person whith replased valve the situation should be reevaluated. If I was the treating doctor I would recommend some examination like a cardiac echo to evaluate heart function and valves, a full blood analyze to exclude anemia,electrolyte imbalances and d-dimer to exclude any pulmonar thromboembolism. After this we can better understand what we are dealling whith and if it is necesary to add another treatment or rise diuretic dosage. Hope I was helpfull. Best regards,Dr.Ervina