Surgery Insight: surgical methods to reverse left ventricular remodeling

Temporal pattern of left ventricular structural and functional remodeling following reversal of volume overload heart failure

Current surgical management of volume overload-induced heart failure (HF) leads to variable recovery of left ventricular (LV) function despite a return of LV geometry. The mechanisms that prevent restoration of function are unknown but may be related to the timing of intervention and the degree of LV contractile impairment. This study determined whether reduction of aortocaval fistula (ACF)-induced LV volume overload during the compensatory stage of HF results in beneficial LV structural remodeling and restoration of pump function. Rats were subjected to ACF for 4 wk; a subset then received a load-reversal procedure by closing the shunt using a custom-made stent graft approach. Echocardiography or in vivo pressure-volume analysis was used to assess LV morphology and function in sham rats; rats subjected to 4-, 8-, or 15-wk ACF; and rats subjected to 4-wk ACF followed by 4- or 11-wk reversal. Structural and functional changes were correlated to LV collagen content, extracellular matrix (ECM) proteins, and hypertrophic markers. ACF-induced volume overload led to progressive LV chamber dilation and contractile dysfunction. Rats subjected to short-term reversal (4-wk ACF + 4-wk reversal) exhibited improved chamber dimensions (LV diastolic dimension) and LV compliance that were associated with ECM remodeling and normalization of atrial and brain natriuretic peptides. Load-independent parameters indicated LV systolic (preload recruitable stroke work, Ees) and diastolic dysfunction (tau, arterial elastance). These changes were associated with an altered α/β-myosin heavy chain ratio. However, these changes were normalized to sham levels in long-term reversal rats (4-wk ACF + 11-wk reversal). Acute hemodynamic changes following ACF reversal improve LV geometry, but LV dysfunction persists. Gradual restoration of function was related to normalization of eccentric hypertrophy, LV wall stress, and ECM remodeling. These results suggest that mild to moderate LV systolic dysfunction may be an important indicator of the ability of the myocardium to remodel following the reversal of hemodynamic overload.

Ulcerated calcification of the interventricular septum causing transient ischemic attacks: case report

Background

Calcific deposits are frequently observed at sites of healed myocardial infarcts. Grossly visible calcification of myocardial infarcts and calcified intracavitary cardiac thrombi are less common but recently are becoming more frequent findings during surgical ventricular restoration procedures.

Case Presentation

A 64 years old male diabetic patient experienced two episodes of transient ischemic attacks during the last six months. During the diagnostic work up he was found to have triple vessel coronary artery disease with mild left ventricular dysfunction, akinesia of the anterior-apical wall and hypokinesia of the inferior wall. He was referred to our department for coronary artery bypass grafting. He underwent elective triple coronary artery bypass and a ventricular restoration procedure due to apical wall thinning. The inspection of the left ventricle revealed an ulcerated round shape calcification of the interventricular septum with a crater filled with clot. We resected the above lesion and covered the damaged area with the septal Dacron patch of the modified linear closure. The patient was discharged from the hospital on the 11^th postoperative day and has been doing well 6 months later, with improvement in both ventricular function and clinical status.

Conclusion

The exploration of the left ventricular cavity reveals interesting phases of the post-infarction healing process. The suspicion of left ventricular thrombosis in patients with ventricular asynergy justifies a ventricular exploration during coronary artery bypass surgery.