Cardiology Online Case-discussion Chapter – Idiopathic Dilated Cardiomyopathy and role of defibrillator biventricular pacemaker
Case Scenario: Sixty-seven year- old female who presented to the outpatient department with a several week history of exertional shortness of breath, more so when she takes the stairs or goes up a hill. She had undergone a nuclear cardiac stress test 1 year previously and this was normal. ECG was done and presented below. She has otherwise no cardiac history and has continued to remain healthy with a reasonably active life style.
Examination and Investigations – Patient was resting comfortably speaking in full sentences. Blood pressure 110/72mmHg and pulse 74/min. estimated jugular venous pressure was felt to be normal. Cardiac examination was normal with the exception of a pradoxically split second heart sound. Her lungs sere clear. Her extremities demonstrated no edema. – A transthoracic echocardiogram was performed and this confirmed a mildly dilated left ventricle with a global reducation in left ventricular systolic function with an estimated left ventrcular ejection fraction of 25%. The left atrium was moderately enlarged. The right atrium was normal. The mitral valve demonstrated mild to moderate central mitral regurgitation. No other findings of abnormal significance were seen.
A 12-lead ECG was performed and this demonstrated a normal sinus rhythm rate of 74/min. A widened QRS complex is demonstrated greater than 120 msec in duration. There is complete LBBB pattern. Additionally, a terminally negative P wave is seen in lead V1 supporting left atrial abnormality.
The patient subsequently underwent a left heart catheterization confirming a global moderately severe reduction of left ventricular systolic function and normal epicardial coronary arteries.
The Patient presented with subacute shortness of breath in the setting of unexplained left ventricular systolic dysfunction and an antecedent history of complete LBBB. She was deemed to have non-ischemic left ventricular systolic dysfunction base on her diagnostic left heart catheterization. Treatment with oral beta blockade, an ACE inhibitor, and a low dose diuretic was instituted with prompt improvement of her symptomatology.
After an appropriate interval, follow-up transthoracic echocardiography was performed, which failed to demonstrate improved left ventricular systolic function. She next underwent placement of a biventricular pacemaker defibrillator. Follow-up transthoracic echocardiography at 3 months post defibrillator placement demonstrated near normalization of her left ventricular systolic function that has persisted since her defibrillator biventricular pacemaker placement over the past 2 years.
In the interim, the patient did present with several defibrillator shocks, and upon device interrogation she was noted to be in paroxysmal atrial fibrillation with a rapid ventricular response. She was started on an anti-arrhythmic medication and has done well since without further episodes of atrial fibrillation or defibrillator discharge. She remains in a functional class I performance status.
Why was the case Chosen?
Patients with a complete LBBB and symptomatic CHF can benefit from Biventricular cardiac pacing with a significant improvement in left ventricular systolic function. Generally, the wider the QRS complex with a left bundle branch QRS complex morphology, the greater the likelihood of being a positive responder to biventricular pacing.
Learning points from the case/how the case altered the treatment pattern
This patient with a functional class II performance status in the setting of a complete left bundle branch block of uncertain etiology. After further evaluation, non-ischemic left ventricular systolic dysfunction was highly suspected. After appropriate placement on oral medications, a follow-up of her left ventricular systolic function failed to demonstrate an improvement, and thus she was deemed to be an excellent candidate for an implantable biventricular pacemaker defibrillator. While not all patients respond favorably to biventricular pacing, she has demonstrated a remarkable response not only in the objective improvement with regard to her left ventricular ejection fraction, but also her complete resolution of any cardiovascular symptomatology. A complete LBBB is not a normal finding a merits further investigation. Often times , it can precede the development of subsequent left ventricular systolic dysfunction and if upon initial evaluation the left ventricular systolic function is deemed to be normal , follow-up evaluation both clinically and with cardiac imaging is suggested to ensure that left ventricular systolic dysfunction has not transpired . A additionally , depending on the patient’s function status and symptom , an evaluation of the patient’s coronary artery status is often indicated either in the form of cardiac stress imaging or a diagnostic left heart catheterization depending on the clinical situation .
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