Changes in left ventricular volume and decline in ejection fraction after degenerative mitral valve repair: The math makes sense

Structural Heart Interventions During COVID-19

The spread of Coronavirus Disease 2019 (COVID-19) pandemic across the globe and the United States presented unprecedented challenges with dawn of new policies to reserve resources and protect the public. One of the major policies adopted by hospitals across the nations were postponement of non-emergent procedures such as transaortic valve replacement (TAVR), left atrial appendage closure device (LAAC), MitraClip and CardioMEMS. Guidelines were based mainly on the avoidable clinical outcomes occurring during COVID-19 era. As our understanding of the SARS-CoV-2 evolved, advanced cardiac procedures may safely continue through careful advanced coordination. We aim to highlight the new guidelines published by different major cardiovascular societies, and discuss solutions to safely perform procedures to improve outcomes in a patient population with high acuity of illness during the COVID-19 pandemic era.

Mitigating cardiac dysfunction by TOE-guided cardioplegia and mitral valve repair

Based on current guidelines, 15% to 20% of patients undergoing mitral valve repair for regurgitation develop left ventricular dysfunction (ejection fraction < 50%-55%) despite a normal baseline. Two schools of thought have been debated: preexisting myocardial disease or suboptimal intraoperative myocardial protection. In our view, they could be reconciled. It is well recognized that left ventricular ejection fraction with a standard cut off at 50%-55% has limited sensitivity in detecting early systolic impairment in mitral regurgitation patients. Mitral regurgitation also leads to mitochondrial oxidative stress, thus rendering the myocardium more susceptible to ischemia-reperfusion injury and precipitating postoperative cardiac dysfunction. The fall in left ventricular ejection fraction early after mitral valve repair was shown to be caused by the reduction in both myocardial contractility and left ventricular stroke volume. To mitigate the risk to myocardial reperfusion injury, appropriate cardioplegia volume and distribution and well-defined surgical repair processes are equally important. We use transesophageal echocardiography-guided cardioplegia delivery, imaging the intramyocardial flow and ensuring adequate protection of the subendocardium during mitral valve repair. Mild aortic regurgitation on a beating heart often leads to left ventricular dilatation with diminished cardioplegia flow in the myocardium, thus requiring direct ostia cardioplegia. Systematic transesophageal echocardiography assessment before surgery is essential for establishing the mitral regurgitation mechanisms and translating them into precise surgical repair strategies. The benefits of transesophageal echocardiography-guided cardioplegia delivery warrant further clinical trials in order to evolve into part of a high surgical standard.