Global Cardiology Science and Practice - Current Issue

Marfan syndrome is a genetic disease with variable clinical presentation. This case describes a 36-year-old lady who was diagnosed with Marfan syndrome based on revised Ghent criteria. She was found to have bicuspid aortic valve and sensorineural hearing loss. Inferior vena cava stenosis was suspected on echocardiography due to high velocity flow and visualization of a focal narrowing in the inferior vena cava proximal to hepatic vein entry. Inferior vena cava stenosis was confirmed by computed tomography. Echocardiographic features suggestive of inferior vena cava stenosis include detection of a focal narrowing and high turbulent flow, peak velocity > 1.5 m/s and S/D wave fusion on spectral Doppler.

While cardiac involvement is not a common presentation in human echinococcosis, it may lead to life-threatening complications including cyst rupture; anaphylactic shock; tamponade; pulmonary, cerebral or peripheral arterial embolism; acute coronary syndrome; dysrhythmias; infection; ventricular or valvular dysfunction, as well as sudden death. Here we report a 9-year old girl who was diagnosed to have hydatid cyst of the interventricular septum four years after diagnosis and medical treatment of pulmonary hydatidosis. Presentation, management and follow-up of the patient is discussed.

A large number of clinical trials over the last 30 years have firmly consolidated the importance of lowering low density lipoprotein cholesterol (LDLc) in the prevention of cardiovascular diseases (CVD) and its associated devastating sequelae.¹ While healthy diets and exercise are highly recommended to lower LDLc levels, in many individuals with high baseline levels of LDLc, this is not sufficient to bring levels down to recommended target values in order to prevent recurrent coronary heart disease and cardiovascular complications. This is especially true for patients at high risk of premature cardiovascular death and disability, including those with familial hypercholesterolaemia (FH). FH is a very common inherited disease – affecting at least 30 million people worldwide, with an overall incidence of 1:200 globally² – of whom ≤  1% have been diagnosed. The advent of HMG-CoA reductase inhibitors, also known as “statins”, and their first application to hypercholesterolemic patients over 30 years ago, has revolutionized the treatment of FH patients and resulted in substantial lowering of LDLc. In addition, cholesterol–lowering drugs, such as “ezetimibe” that blocks cholesterol absorption from the gut by inhibiting the Niemann-Pick C1-like 1 (NPC1L1) transporter, have also been successful and a 7-year IMPROVE-IT trial revealed that a “simvastatin-ezetimibe” combination resulted in an incremental lowering of LDLc levels and a modest 2% improved cardiovascular outcomes.³ Therefore, it became clear that additional treatments are needed to substantially decrease LDLc and efficiently protect against CVD.

Bioresorbable polymers and biocorrodible metals are the latest developments in biodegradable materials used in interventional cardiology for the mechanical treatment of coronary atherosclerosis. Poly-L-lactic acid is the most frequently used bioresorbable polymer and initial evidence of feasibility, efficacy and clinical safety following deployment of polymer-based platforms was gained after completion of the first-in-man longitudinal ABSORB registries, Cohorts A and B and ABSORB Extend.

In these studies, the biologic interaction of the first-generation Absorb Bioresorbable Vascular Scaffold (BVS) (Abbott Vascular, SC, Calif., US) with the underlying vascular tissue was evaluated in vivo with multiple imaging modalities such as intravascular ultrasound (IVUS), virtual histology-IVUS, IVUS-palpography, optical coherence tomography as well as ex vivo with coronary computed tomography. Efficacy measures following this in vivo multi-imaging assessment as well as clinical safety were comparable with current generation drug-eluting stents (DES) (Abbott Vascular, SC, Calif., US) in non-complex lesions over a 3-year follow-up. Furthermore, novel properties of functional and anatomic restoration of the vessel wall during the late phases of resorption and vascular healing were observed transforming the field of mechanical treatment of atherosclerosis from delivering only acute revascularization to additionally enable late repair and subsequent restoration of a more physiologic underlying vascular tissue.

Despite the sufficient evidence and the subsequent Conformité Européenne mark approval of the first fully biodegradable scaffold (Absorb BVS) in 2012 for revascularizing non-complex lesions, the paucity of randomized comparisons of fully bioresorbable scaffolds (BRS) with metallic DES in a “real-world” clinical setting raised controversies among the interventional community for the merit of these technologies. Only recently, results from international large-scale randomized trials from the United States (U.S.), China and Japan were revealed.

Herein we provide a comprehensive overview of the ABSORB III, ABSORB China and ABSORB Japan studies demonstrating the consistent non-inferiority in clinical safety and efficacy measures of the Absorb BVS vs. current generation DES.

The impetus for developing drug-eluting bioresorbable scaffolds (BRS) has been driven by the need for elastic and transient platforms instead of stiff and permanent metallic implants in diseased coronary anatomies. This endeavor would prevent acute recoil or occlusion, allow sealing of post-procedural dissections following acute barotrauma, provide inhibition of in-segment restenosis through efficient drug-elution and would further prepare the vessel to enter a reparative phase following scaffold resorption. Biocorrodible metallic platforms have been introduced as alternatives to bioresorbable polymeric scaffolds for the treatment of significant atherosclerosis and in view of the body of evidence derived from recent clinical trials we elaborate on the clinical safety and efficacy of these devices in interventional cardiology.

Wave intensity analysis (WIA) is a technique developed from the field of gas dynamics that is now being applied to assess cardiovascular physiology. It allows quantification of the forces acting to alter flow and pressure within a fluid system, and as such it is highly insightful in ascribing cause to dynamic blood pressure or velocity changes.

When co-incident waves arrive at the same spatial location they exert either counteracting or summative effects on flow and pressure. WIA however allows waves of different origins to be measured uninfluenced by other simultaneously arriving waves. It therefore has found particular applicability within the coronary circulation where both proximal (aortic) and distal (myocardial) ends of the coronary artery can markedly influence blood flow. Using these concepts, a repeating pattern of 6 waves has been consistently identified within the coronary arteries, 3 originating proximally and 3 distally. Each has been associated with a particular part of the cardiac cycle.

The most clinically relevant wave to date is the backward decompression wave, which causes the marked increase in coronary flow velocity observed at the start of the diastole. It has been proposed that this wave is generated by the elastic re-expansion of the intra-myocardial blood vessels that are compressed during systolic contraction. Particularly by quantifying this wave, WIA has been used to provide mechanistic and prognostic insight into a number of conditions including aortic stenosis, left ventricular hypertrophy, coronary artery disease and heart failure. It has proven itself to be highly sensitive and as such a number of novel research directions are encouraged where further insights would be beneficial.

Angiopoietin-like proteins (ANGPTLs) have emerged as an important regulator of lipid and glucose metabolism, as well as insulin sensitivity. ANGPTL3 plays a key role in regulating circulating triglycerides (TG) and cholesterol levels through reversible inhibition of lipoprotein lipase (LPL) and endothelial lipase enzymes activity. Loss of function mutation of ANGPTL3 gene has been identified in many subjects with familial combined hypolipidemia. ANGPTL4 produces irreversible inhibition of LPL activity, while ANGPTL8 enhances the activity of ANGPTL3, which highlight the interplay between the different ANGPTLs in a coordinated manner to regulate lipid metabolism during different nutritional states. This new class of lipid modulators may serve as potential novel therapeutic target for reducing plasma lipoprotein and treatment of metabolic syndrome.

“… it is better to dissect nature, than to reduce her to abstraction”

Francis Bacon, Novum oragnum scientiarum, 1620

The mechanisms responsible for sustaining atrial fibrillation are a key debate in cardiovascular pathophysiology, and directly influence the approach to therapy including ablation. Clinical and basic studies have split AF mechanisms into two basic camps: ‘spatially distributed disorganization’ and ‘localized sources’. Recent data suggest that these mechanisms can also be separated by the method for mapping – with nearly all traditional electrogram analyses showing spatially distributed disorganization, and nearly all optical mapping studies showing localized sources. We will review this dichotomy in light of these recently identified differences in mapping, and in the context of recent clinical studies in which localized ablation has been shown to impact AF, also lending support to the localized source hypothesis. We will conclude with other concepts on mechanism-based ablation and areas of ongoing research that must be addressed to continue improving our knowledge and treatment of AF.