Richard R. Heuser

Percutaneous Treatment for Mitral Regurgitation: The QuantumCor System

AIMS Percutaneous edge-to-edge techniques and annuloplasty have been used to treat mitral regurgitation (MR). However, neither intervention can be performed reliably a second time and, with annuloplasty, a foreign body is left behind. The mitral and tricuspid annuli are areas of dense collagen (Fig. 1); treatment with radiofrequency (RF) energy in sheep reduces their size, and can be repeated without affecting the coronary sinus. RF energy may also be used in leaflet procedures. Our aim was to improve mitral valve competence using techniques that can be incorporated into a minimally invasive approach. METHODS In open-heart procedures in 16 healthy sheep (6 with naturally occurring MR), we used a malleable probe (QuantumCor, Inc., Lake Forest, CA) that conforms to the annular shape to deliver RF energy via a standard generator to replicate a surgical mitral annular ring. Four segments of the posterior mitral valve annulus were treated while on cardiopulmonary support via a left thoracotomy with access via the atrial appendage. Seven sheep were followed chronically. RESULTS All sheep underwent intracardiac echocardiography (ICE) or direct circumferential measurement of the mitral annulus before and after RF therapy. RF therapy was administered in less than 4 minutes in each case, and the mean anteroposterior (AP) annular distance was reduced by a mean of 5.75 +/- 0.86 mm (23.8% reduction, P< 0.001). In the 6 sheep with nonischemic MR, regurgitation was eliminated. Acute histopathology (HP) demonstrated no damage to the leaflets, coronary sinuses, or coronary arteries. At 30 days, the AP distance continued to be reduced in the 7 surviving sheep (mean 5.0 +/- .6 mm, 21.4% reduction, P< 0.001). CONCLUSIONS In a sheep model, RF energy applied for less than 4 minutes per case at subablative temperatures in four quadrants of the posterior mitral valve annulus reduced the AP and circumferential annular distances significantly, and eliminated nonischemic MR. Results will need to be confirmed in follow-up studies to determine safety and efficacy. RF energy administered as a novel, percutaneous method of mitral valve annuloplasty may have the potential to reduce morbidity and mortality associated with current surgical techniques.

The QuantumCor device for treating mitral regurgitation: an animal study.

Objectives: The mitral annular contraction achieved could help reduce mitral regurgitation (MR), and with appropriate modifications, be applied to human subjects providing a potentially effective percutaneous method of valve repair. Background: MR is an important source of morbidity and is an independent predictor of mortality. A variety of percutaneous approaches are being developed to address this issue. We introduce a novel potential method utilizing radiofrequency (RF) energy to heat and shrink the mitral valve annulus in an animal model. Methods: In open‐heart procedures in 16 healthy sheep (six with naturally occurring MR), we used a malleable probe (QuantumCor, Lake Forest, CA) that conforms to the annular shape to deliver RF energy via a standard generator to replicate a surgical mitral annular ring. Seven sheep were followed chronically and their mitral annulus dimensions measured serially. Results: All sheep underwent intracardiac echocardiography or direct circumferential measurement of the mitral annulus before and after RF therapy. RF therapy was administered in less than 4 min in each case, and the mean anteroposterior (AP) annular distance was reduced by a mean of 23.8% (AP diameter reduction 5.75 ± 0.86 mm, P < 0.001) acutely. In the six sheep with nonischemic MR, regurgitation was eliminated. Acute histopathology (HP) demonstrated no damage to the leaflets, coronary sinuses, or coronary arteries. At the end of the intended 6‐month period of the chronic part of the study, four of the seven animals survived. The four treatment animals showed significant reductions in mitral A‐P dimension, with a percent diameter reduction of 26.4% (AP diameter reduction 7 ± 2.3 mm). Conclusion: The application of RF directly to heat the mitral annulus has resulted in sustained contraction of the annulus in this limited preclinical animal study. With further study and possible modifications, it holds promise for future application in human subjects with MR.

Treatment of lower extremity vascular disease: the Diamondback 360°™ Orbital Atherectomy System

Atherosclerotic disease affecting the arteries of the lower extremities becomes symptomatic with the onset of pain either at rest or with ambulation. The disease, commonly referred to as peripheral arterial disease (PAD), affects nearly 30 million individuals in Europe and North America alone. The predominant factor responsible for the impaired functional capacity and quality of life in the presence of lower-extremity PAD is inadequate blood flow due to atherosclerotic plaque build-up within the arteries. Without successful lifestyle risk modifications or judicious pharmacotherapy, individuals with lower-extremity PAD may develop disabling complications that require endovascular treatment, bypass surgery or amputation of the affected extremity. The Diamondback 360°™ Orbital Atherectomy System is a promising new methodology for treating symptomatic PAD within the major and branch arteries of the leg. The device differs from other atherectomy technologies by its unique orbiting action to remove plaque and the ability to increase lumen diameter by increasing the orbital speed. Applying the principles of centrifugal force, an eccentrically mounted diamond-coated crown rotates at high speed to sand away plaque as the crown is slowly advanced through the narrowed or occluded section of artery. As crown rotation increases, centrifugal force presses the crown against the stenotic lesion to effect plaque removal, while the less diseased, more elastic arterial wall flexes away from the crown, minimizing the risk of vessel trauma. The increasing crown orbit creates a larger lumen and minimizes procedure time and the need for catheter upsizing. This device profile presents an overview of the prevalence and symptoms of PAD, describes the Diamondback 360 Orbital Atherectomy System components and mechanism of action, and closes with a case study review and perspective regarding how lower-extremity PAD will be treated in the next 5 years.

Remodeling of the mitral valve using radiofrequency energy: review of a new treatment modality for mitral regurgitation.

Mitral regurgitation (MR) is a common valvular pathology with significant morbidity and mortality implications. Mechanical treatment of this condition is more effective than medical treatment and surgical correction has traditionally been the mechanical method of choice. Following major advances and wide acceptance of percutaneous interventions for coronary artery diseases, the field of valvular heart disease became an attractive target for transcatheter treatment modalities. Significant steps have been achieved in the field of percutaneous treatment of mitral stenosis as well as aortic stenosis, and lately, mitral regurgitation has been the focus of interest for many investigators looking for transcatheter solutions. Percutaneous edge-to-edge techniques and annuloplasty are innovative but have many disadvantages including the inability to reintervene and leaving a foreign body behind, respectively. Since the mitral and tricuspid annuli have dense collagen, a treatment modality targeting that collagen is logical. Observing the thermal effect on collagen, which causes conformational changes and shrinkage, radiofrequency energy was tested to evaluate its effect on the collagen-rich structure that is the mitral valve annulus. The potential of shrinking the mitral annulus by applying direct thermal source could be a promising modality for the treatment of mitral regurgitation with potential open and percutaneous applications. This paper presents an overview of the recent advances in transcatheter treatment of mitral regurgitation focusing on a new treatment modality that aims at reducing the mitral valve annulus diameter through the direct application of thermal energy using a radiofrequency energy probe.

Chronic total occlusions in peripheral vasculature: techniques and devices.

Peripheral artery disease continues to increase in an ever-aging society and consumes a significant part of health resources. Chronic total occlusions account for a significant portion of the lesions encountered by endovascular interventionalists. Unlike the coronary circulation, these occlusions are often long and associated with other features of complexity. The two primary issues concerning these lesions are the ability to safely achieve intimal angiographic success and the long-term durability of therapy. Traditionally, the use of percutaneous techniques was limited to certain anatomic subsets, such as stenosis or total occlusions. However, recent advances in wire technology, re-entry catheters, alternative crossing tools and atherectomy devices have increased the interventional armamentarium for this challenging disease subset. This article will focus on some of the techniques in crossing chronic total occlusions lesions, as well as the available devices to improve long-term patency.

The Impella ventricular assist device: use in patients at high risk for coronary interventions: successful multivessel percutaneous coronary intervention in a 62-year-old high-risk patient

The Impella Recover LP 2.5 (Abiomed, Danvers, MA, USA) is a ventricular assist device that is easily placed and has low adverse events. It helps unload myocardial demand and enables revascularization in patients who are otherwise at extreme risk for percutaneous coronary intervention (PCI). It breaks the cycle of cardiogenic shock and is indicated in patients with low ejection fraction (EF), acute heart failure, and concurrent high-risk factors for intervention or surgery. Many case reports have been published regarding use of this device in high-risk PCIs, but successful intervention in two high-risk vessels in one setting has rarely been reported. We describe such a case report here where two critical lesions in LAD and circumflex arteries were successfully intervened on with the assistance of this device.

Chronic total occlusions: Successful recanalization of very old lesions

The treatment of chronic total occlusion is thought to be the final frontier in treating coronary artery disease nonsurgically. In the past, an old occlusion was not likely to be treated successfully percutaneous. We have had success in revascularizing some very old 20 plus year old occlusions percutaneously.

Collagen Mechanics: A Rationale for Radiofrequency Energy to Treat Mitral Regurgitaton

Despite a variety of pharmacological interventions to limit the regurgitant fraction, mitral regurgitation requires surgical intervention for definitive treatment. New nonsurgical techniques are being applied to treat mitral regurgitation. The mitral and tricuspid annuli are areas of dense collagen. Application of heat, in the form of radiofrequency energy, can be used to shrink mitral valve annuli and offers a promising approach to the treatment of mitral regurgitation.

The Role for Cardiologists in Stroke Intervention

Even though cardiovascular disease (CVD) is still the leading cause of death in the United States, stroke is the second leading global cause of death behind CVD. In the 21st Century, less than 40% of overall stroke patients are discharged to home and almost 25% of Medicare beneficiaries do not survive 90 days. In spite of the fact that tissue plasminogen activator (TPA) has been approved for stroke care for 20 years, only .75% of annual strokes are actually treated with intravenous (IV) TPA. Similar to how interventional cardiologists evolved from IV to catheter mechanical treatment for acute myocardial infarctions (AMI) over 30 years ago, over the last few years, neurointerventionists now perform endovascular stroke therapy in many of these patients using stent retrievers. However, very few stroke patients are actually getting treatment, and neurointerventionists on an average perform only 8 stroke interventions per year. It has been recently shown that 9 out of 10 strokes can be prevented by controlling CVD risk factors. A principal job for cardiologists is to recognize and manage these CVD risk factors in addition to being involved with performing intervention. Atrial Fibrillation is certainly a common problem in all of our practices and puts people at five-fold higher risk of stroke. Cardiovascular cardiology teams already have 24/7 coverage for acute interventions for AMI in place at their facilities. A number of groups have replicated acute stroke care performed by cardiologists at centers worldwide with outstanding results. It makes sense that we try to build a collaboration among neuroradiologists, interventional cardiologists and perhaps vascular or neurosurgeons with expertise in acute endovascular procedures to develop programs for acute and active 24/7 stroke care similar to systems for primary angioplasty for AMI.

What is a cardiologist to do: And it can only get better

So, what are you going to do? A 68-year old patient presents with a myocardial infarction at an outlying hospital without a cath lab and he receives thrombolytic therapy. He is undergoing continued ischemic pain without resolution of his ST elevation on the ELG. He received the agent 4 h ago and you have achieved arterial access. Your nurse asks you what form of anticoagulation you want the patient to receive. Sardi et al. have given us some direction. In their consecutive series in this exact scenario, 104 patients were treated with either Bivalirudin (BIV) or unfractionated Heparin (UFH). The patients treated with BIV had a significantly lower incidence of the composite endpoint. This difference was primarily driven by a lower incidence of death, major bleeding, and postprocedure reinfarction in the BIV treated patients [1]. We know that BIV has been shown to be at least equivalent to UFH in conjunction with glycoprotein IIb/IIIa inhibitors from a number of studies [2–4]. These studies also highlighted the reduction in bleeding utilizing BIV. Now we know that it appears also to be safe in patients who present with thrombolytics on board. This is not an unlikely scenario for those of us on the front lines in acute cardiovascular care. What is gratifying is that these procedures were done in the “prehistoric era” of femoral access. In fact, the femoral route for interventional access was used in all cases with the predominant sheath size 6 French. A recent retrospective study from the National Cardiovascular Data Registry [5] has given us radialists’ an exciting view of where things are going in the United States. They looked at nearly 3 million procedures from the CathPCI registry and the incidence of radial percutaneous coronary intervention (PCI) has gone from 1.2% in 2007 to 16.1% in 2012. They happily reported that one in six PCIs performed in contemporary clinical practice are done via the radial route. Putting this in perspective, virtually all of the patients described in Sardi’s article would have benefited further from this access, primarily by reducing the incidence of bleeding. We have gained knowledge through this report of a series of patients presenting to a high-volume laboratory after receiving thrombolytic therapy. We are a radial first laboratory, and I have encouraged sites that are becoming radial friendly to completely switch over including using radial access for myocardial infarction. Can you imagine how much safer post-thrombolytic procedures will become when more of us become “radialphiles.”