Ottavio Alfieri

Recovery of myocardial function. The ultimate target of coronary revascularization. Discussion

Recovery of myocardial contraction represents an important target of coronary revascularization and the preoperative recognition of viable akinetic (hibernating) myocardium is a crucial point of the preoperative investigation of patients with chronically depressed left ventricular function. In 14 patients dobutamine infusion during echocardiography was utilized to evoke the contractile reserve retained by viable akinetic segments. Redistribution of thallium(TI)-201 after the rest injection was also used to assess the viability of akinetic areas. The wall motion response to dobutamine infusion predicted immediate postoperative improvement in 85 of 93 segments (sensitivity 91.3%) and identified 25 of the 32 segments which did not exhibit early postoperative improvement (specificity 78.1%). Rest redistribution of TI-201 demonstrated high sensitivity (93.0%) but low specificity (43.7%) for predicting the early recovery of regional wall motion. When late recovery was also considered, the specificity of this method increased to 64.0%. Rest distribution of TI-201 identifies viability which is not necessarily associated with the early recovery of function postoperatively. When the echo-dobutamine test is positive, on the other hand, the recovery of function usually occurs immediately after revascularization and the operative risk is expected to be low even in the presence of severely compromised left ventricular function.

Left ventricular dysfunction due to stunning and hibernation in patients

SummaryLeft ventricular dysfunction is in most cases the consequence of myocardial ischemia. It may occur transiently during an attack of angina and usually it is reversible. It may persist over hours or even days in patients after an episode of ischemia followed by reperfusion, leading to the so-called condition of stunning. In patients with persistent limitation of coronary flow, left ventricular dysfunction may be present over months and years, or indefinitely in subjects with fibrosis, scar formation, and remodeling after myocardial infarction. Bowever, chronic left ventricular dysfunction does not mean permanent or irreversible cell damage. Bypoperfused myocytes can remain viable but akinetic. This type of dysfunction has been calledhibernating myocardium. The dysfunction due to hibernation can be partially or completely restored to normal by reperfusion. It is, therefore, important to clinically recognize a hibernating myocardium. In the present article we evaluate stunning and hibernation with respect to clinical decision making and, when possible, we refer to our ongoing clinical experience.

Surgical management of left ventricular free wall rupture after acute myocardial infarction

Left ventricular rupture after acute myocardial infarction occurs more often than suspected and diagnosis is rarely made before death. Left ventricular rupture has been reported to contribute to the overall in-hospital mortality after acute myocardial infarction in up to 24% of cases and to be present in 40% of patients dying within the first week after infarction. Only prompt diagnosis and aggressive surgical treatment can be lifesaving under these circumstances. Between February 1991 and August 1993 five patients underwent emergency operation for left ventricular rupture after acute myocardial infarction using exclusively transoesophageal echocardiography as a diagnostic tool. All patients had evidence of cardiac tamponade and electrocardiography showed signs of anterolateral acute myocardial infarction in one, inferolateral acute myocardial infarction in three and lateral acute myocardial infarction in one. In two cases the infarcted area was debrided and an interrupted pledgetted 2/0 polypropylene suture was placed from inside of the ventricle outward to the epicardial surface and then through the pericardial patch. In the other three cases an original technique was used: an autologous glutaraldehyde-stiffened pericardial patch was sealed over the infarcted area using fibrin glue and fixed with running suture on the surrounding healthy myocardium. One patient died in the operating room because of low cardiac output syndrome which was possibly the result of an excessively extended area of infarction. Left ventricular rupture is a catastrophic complication of acute myocardial infarction and prompt diagnosis with transoesophageal echocardiography followed by emergency operation can be lifesaving.(ABSTRACT TRUNCATED AT 250 WORDS)

Hibernating myocardium in patients with coronary artery disease: Identification and clinical importance

SummaryThe term hibernating myocardium describes a particular outcome of myocardial ischemia in which myocytes show a chronically depressed contractile ability but remain viable. Revascularization of hibernating tissue causes a recovery of mechanical function that correlates with long-term survival. Therefore it is important clinically to distinguish hibernating from infarcted myocardium, since asynergies due to hibernation will improve on reperfusion, whilst those due to infarct will not. One suggested technique to identify hibernating myocardium is to stimulate the myocytes acutely, but briefly, by administration of inotropic agents while monitoring contractile function by echocardiography. We report our experience on the use of low dosages of dobutamine. Myocardial viability was validated by measuring the recovery in contraction of the akinetic areas after coroanry artery bypass surgery by means of intraoperative epicardial echocardiography. The test has a sensitivity of 93% and a specificity of 78%. It is useful for identification of viable myocardium and also for quantification of intraoperative risk in individual patients. Limitations of this test are related to the presence of downregulation of beta receptors and to the impossibility of differentiating hibernating from stunned myocardium. Another useful technique of identifying hibernating myocardium is the use of radionuclear markers for viability. In our experience the two most important tests are (1) rest-redistribution imaging of thallium 201 (which has a high sensitivity of 93% but a low specificity of 44%) and (2) 99mTe-Sestamibi imaging, which provides information on both perfusion and function with a single injection. This latter technique allows differentiation between stunning and hibernating on the basis of coronary flow, which is preserved in stunning and reduced in hibernation.

Tricuspid Valve Disease: Surgical Techniques

Tricuspid valve disease remains an intricate and debated field in terms of pathophysiology, surgical indications and treatment options. In this chapter, surgical techniques, both for repair and replacement of the tricuspid valve will be described in details. Functional (secondary) and organic (primary) tricuspid regurgitation will be addressed and a challenging scenario, like late tricuspid regurgitation following previous mitral valve surgery, will be emphasized.

Surgical Aspects of Paravalvular Leak

Paravalvular leak (PVL) is a common complication after surgical valve replacement, with reported incidences at follow-up varying from 2% to 17% in both mitral and aortic positions [1–3].

Percutaneous Approaches to Functional Tricuspid Regurgitation

Functional tricuspid regurgitation (TR) is the most frequent etiology of tricuspid valve pathology in Western countries. Surgical avoidance of tricuspid repair has been accepted for years, based on the misleading concept that TR would disappear once the primary left-sided problem is treated. The current prevalence of moderate-to-severe TR is about 1.6 million in the United States, with only a small proportion treated, resulting in a large number of untreated patients with functional TR. Furthermore, significant residual TR has been reported in 10–45 % of patients after tricuspid surgical repair with different techniques. As a result, the pathophysiology and treatment of functional TR has gained significant interest in recent years. Percutaneous procedures may be an attractive alternative to surgery for patients deemed to be high-risk surgical candidates. Some of the concepts that have been developed for the percutaneous treatment of aortic and mitral regurgitation are currently being adapted to percutaneous tricuspid valve procedures.

EFFECT OF TRANSCATHETER MITRAL REPAIR WITH THE CARDIOBAND DEVICE ON 3-DIMENSIONAL GEOMETRY OF THE MITRAL ANNULUS

Several transcathether mitral repair devices are currently undergoing clinical studies. The Cardioband system employs direct anchoring to the mitral annulus from the left atrium. We report the acute intraprocedural effects of this device on three-dimensional anatomy of the mitral annulus. This

Results of the Edge-to-Edge Mitral Valve Repair

After its introduction in the early 90s, the edge-to-edge (EE) technique has been used in patients with mitral regurgitation (MR) due to different etiologies and mechanisms. More than 20 years after its introduction, it is now clear that the best indications for the EE repair are represented by bileaflet prolapse (facing segments), segmental anterior leaflet prolapse/flail and commissural prolapse/flail. In addition this technique does have an important role also in functional mitral regurgitation, and as a “rescue” procedure in case of suboptimal conventional mitral reconstruction (“rescue” EE). Finally it has been used for the prevention/treatment of SAM. In this chapter the results of the EE repair in the most common indications described above will be outlined and discussed.