Basic science investigations span an array of inquiries, such as understanding the basic mechanisms underlying cardiac dyssynchrony and resynchronization in the failing heart, and beneficial influences of nitric oxide/cGMP/protein kinase G and cGMP-targeted phosphdiesterase signaling cascades on cardiac maladaptive stress remodeling. Recently, the latter has particularly focused on the role of phosphodiesterase type 5 and its pharmacologic inhibitors (e.g. sildenafi, Viagra®), on myocyte signaling cascades modulated by protein kinase G, and on the nitric oxide synthase dysregulation coupled with oxidant stress. The lab also conducts clinical research and is presently exploring new treatments for heart failure with a preserved ejection fraction, studying ventricular-arterial interaction and its role in adverse heart-vessel coupling in left heart failure and pulmonary hypertension, and testing new drug, device, and cell therapies for heart disease. A major theme has been with the use of advanced non-invasive and invasive catheterization-based methods to assess cardiac mechanics in patients.asive and invasive catheterization-based methods to assess cardiac mechanics in patients. David Kass, MD, is currently the Director at the Johns Hopkins Center for Molecular Cardiobiology and a professor in cellular and molecular medicine.

The Cardiology Bioengineering Laboratory, located in the Johns Hopkins Hospital, focuses on the applications of advanced imaging techniques for arrhythmia management. The primary limitation of current fluoroscopy-guided techniques for ablation of cardiac arrhythmia is the inability to visualize soft tissues and 3-dimensional anatomic relationships. Implementation of alternative advanced modalities has the potential to improve complex ablation procedures by guiding catheter placement, visualizing abnormal scar tissue, reducing procedural time devoted to mapping, and eliminating patient and operator exposure to radiation. Active projects include • Physiological differences between isolated hearts in ventricular fibrillation and pulseless electrical activity • Successful ablation sites in ischemic ventricular tachycardia in a porcine model and the correlation to magnetic resonance imaging (MRI) • MRI-guided radiofrequency ablation of canine atrial fibrillation, and diagnosis and intervention for arrhythmias • Physiological and metabolic effects of interruptions in chest compressions during cardiopulmonary resuscitation Henry Halperin, MD, is co-director of the Johns Hopkins Imaging Institute of Excellence and a professor of medicine, radiology and biomedical engineering. Menekhem M. Zviman, PhD is the laboratory manager.