Role of PCI in CAD associated with severe aortic stenosis

Posted on January 27, 2012 by Johnson Francis | Permalink Comments Off

Conventionally CAD (coronary artery disease) associated with severe aortic stenosis is an indication for coronary artery bypass grafting along with surgical aortic valve replacement. But in this era of transcatheter aortic valve replacement (TAVR; also known as transcatheter aortic valve implantation or TAVI), is there a role of PCI (percutaneous coronary intervention) in those awaiting TAVR? Goel SS and colleagues evaluated this aspect in a retrospective analysis of their PCI database. They could identify over two hundred and fifty patients with severe aortic stenosis who had undergone PCI for their associated CAD. They also identified over five hundred patients without aortic stenosis who had undergone PCI using propensity matching. The investigators concluded that percutaneous coronary intervention could be performed in those with severe symptomatic aortic stenosis and CAD with no significant increased risk of short term mortality compared to propensity matched patients without significant aortic stenosis. They also observed that patients with severe left ventricular dysfunction (ejection fraction thirty percent or less) and those with STS (Society of Thoracic Surgeons) score of 10 percent or more are at a highest risk of 30 day mortality after PCI. Online STS risk calculator is available at: http://riskcalc.sts.org/STSWebRiskCalc273/

Angiography and Interventions

AV interval optimization in CRT

Posted on January 27, 2012 by Johnson Francis | Permalink Comments Off

The aim of AV (atrioventricular) interval optimization in CRT (cardiac resynchronization therapy or biventricular pacing) is to prevent too early or too late atrial contraction. Too late an atrial contraction will cause it to overlap with ventricular systole so that atrial contraction will occur against a closed AV valve. This will lead to a sudden elevation of atrial and pulmonary as well as systemic venous pressure. Echocardiographic methods to optimize AV delay are Ritter’s method and Ishikawa’s method. In Ritter’s method, long AV delay is calculated when there is partial fusion of E and A waves on mitral Doppler and short AV delay is calculated when A wave truncation occurs due to ventricular contraction before completion of A wave. From these two values, the optimal AV delay is calculated using the Ritter’s formula.

Ishikawa’s method is used when there is significant diastolic mitral regurgitation. Long AV delay is chosen so that it results in diastolic mitral regurgitation or diastasis until isovolumetric contraction, which is the time at which systolic mitral regurgitation starts. It may be noted that there is no true isovolumetric phase when there is systolic mitral regurgitation as mitral valve starts leaking in the potential isovolumetric phase and reduces the ventricular volume. The duration of diastolic mitral regurgitation is subtracted from the long AV delay to get the optimal AV delay.

Echocardiography, Electrophysiology

AF ablation during therapeutic warfarin levels

Posted on January 25, 2012 by Johnson Francis | Permalink Comments Off

Conventionally, invasive procedures are undertaken by switching over from warfarin to unfractionated heparin to have a better control over bleeding. Santangeli P and associates [Ablation of Atrial Fibrillation under Therapeutic Warfarin Reduces Periprocedural Complications: Evidence from a Meta-Analysis. CIRCEP.111.964916 Published online before print January 23, 2012, doi: 10.1161/?CIRCEP.111.964916] have conducted a meta analysis of published data on the utility of proceeding with atrial fibrillation (AF) ablation while on therapeutic anticoagulation with warfarin. This was prompted by data from observational studies which had suggested that procedures under continuous warfarin usage may reduce the risk of periprocedural complications like thromboembolic events compared to the discontinuation of warfarin and bridging with heparin. They could identify nine studies with a total of over twenty seven thousand patients in which six thousand and four hundred had undergone AF ablation with continuous warfarin regimen. Continuous warfarin usage was associated with a significant decrease in thromboembolic complications (odds ratio = 0.10, P < 0.001) and minor bleeding complications (odds ratio = 0.38, P = 0.002) as compared to discontinuation of warfarin and bridging with heparin. This would call for a large randomized controlled trial to evaluate this concept further.

Cardiology Journal Scan, Electrophysiology

Optical coherence tomography (OCT)

Posted on January 21, 2012 by Johnson Francis | Permalink Comments Off

Optical coherence tomography (OCT) has much higher resolution compared to intravascular ultrasound. It has the resolution of the range of 10 20 microns, which is an order of magnitude better than that of intravascular ultrasound. But the limitation is the lower depth of tissue penetration which is only 2 to 3 millimeters, compared to the 10 millimeter tissue penetration of current intravascular ultrasound probes. Hence it has limitations while imaging large vessels like left main coronary artery and proximal left anterior descending coronary artery. The excellent resolution of optical coherence tomography is very useful in examining the coronary lesion characteristics like plaque rupture and also for monitoring the results of percutaneous interventions with stent deployment. OCT uses light waves instead of ultrasound for imaging. A light emitting source and system to collect the reflected light which checks the intensity of back scatter from internal microstructures with varying optical properties and the time delay of receiving the return signal are part of the OCT device. Since the speed of light is very much faster than that of sound, it is practically impossible to detect time delay of reflected waves electronically. A special device known as time domain OCT interferometer is used for this purpose. OCT is useful in plaque characterisatiion including the measurement of thickness of the fibrous cap which is an important determinant of plaque stability. The macrophage content of the plaque can also be estimated as the macrophages are of relatively large size (20 to 50 microns) and have a high degree of optical contrast. Hence plaques rich in macrophages have a high OCT signal variance. An excellent review on OCT is available at: Cardiac optical coherence tomography. Heart 2008;94:1200-1210, written by Raffel OC and colleagues, in the technology and guidelines section.

Angiography and Interventions

Ultrasonography for detecting radial access site complications

Posted on January 18, 2012 by Johnson Francis | Permalink Comments Off

Uhlemann M et al have reported radial access site complications in their prospective vascular ultrasound registry [The Leipzig Prospective Vascular Ultrasound Registry in Radial Artery Catheterization. Impact of Sheath Size on Vascular Complications. J Am Coll Cardiol Intv, 2012; 5:36-43]. The primary objective of the study was to find the impact of sheath size on the chance of radial artery occlusion. They evaluated over four hundred and fifty patients between 2009 and 2010. Duplex ultrasound studies were done in all patients before discharge. Symptomatic radial artery occlusions were treated with low molecular weight heparin. Total access site vascular complication rate was 14.4 percent with a 5 F sheath and 33.1 percent with a 6 F sheath. Occlusion of the radial artery occurred in 13.7 percent with 5F sheaths and 30.5 percent with 6 F sheath. Other access site complications assessed in the study were hemorrhage, pseudoaneurysm, arteriovenous fistula. 42.5 percent of the radial artery occlusions were immediately symptomatic while seven percent became symptomatic within a mean of four days. Recanalization rates were higher in those who received low molecular weight heparin (55.6% vs. 13.5%, p < 0.001) after a mean period of 14 days. The incidence of radial artery occlusions noted by ultra sound evaluation in this study was surprisingly high, more so in those whom a larger sheath had been deployed.

Angiography and Interventions, Cardiology Journal Scan