Cardiophile » Angiography

Hybrid operating rooms for cardiac procedures

Johnson Francis — Tue, 09 Aug 2011 00:43:05 +0000

A common worry of cardiologists as well as their patients undergoing major catheter interventional procedures is regarding the urgent need for surgical intervention. Usually interventional procedures like balloon angioplasty (fixing up blocks in blood vessels with small catheters or tubes introduced into the blood vessels) are done in the cardiac catheterisation laboratory. If the procedure is not successful or when there is a complication requiring urgent surgical correction, the person has to be shifted to the cardiac surgery theater quickly. Very often there can be logistic issues in shifting a critically ill person, though with advanced interventional technologies which are available now, this is quite a rare occurrence. It is to counter this problem that hybrid operating rooms are being designed. This enables quick switching over from an interventional cardiology approach to a surgical approach without moving the subject from the operating table (or the cath lab table to be precise). Usually cath lab tables are not suited for surgeries and operating tables are not suitable for cath lab procedures as they are not meant for x-ray fluroscopy. Design of a hybrid suite is in such a way that both cardiac catheterisation and angiography with fluroscopy as well as surgical intervention is easily performed. Moreover an increasing number of procedures are being electively designed for hybrid suites. Examples include perventricular closure of ventricular septal defect, percutaneous aortic valve replacement and endovascular repair of aortic aneurysm. In perventricular closure of ventricular septal defect, right ventricle (lower chamber of the heart) is exposed surgically and a catheter based device is used during the operation to close the defect in the septum (separating wall between left and right ventricles). In percutaneous aortic valve replacement, it could be either a femoral or trans apical approach. In femoral approach, the artery (blood vessel carrying oxygenated blood) in the thigh is surgically exposed and further procedure of valve replacement is done using a catheter based device. Trans apical approach involves making a small operation in the lower left portion of the chest where the heart beat is felt and then introducing the device directly to the left ventricle by a catheter based approach. Endovascular repair of aortic aneurysm (enlargement of the main blood vessel of the body carrying oxygenated blood) also involves opening up of the femoral artery in the thigh surgically and further procedure is by catheter based technique. The latter two procedures – endovascular repair of aortic aneurysm and percutaneous aortic valve replacement by the femoral approach can be done in the conventional cardiac catheterisation laboratory as well, without going for a hybrid suite because the surgical exposure is only minimal in these cases.

Concerns about radiation exposure in cardiac CT angiography

Johnson Francis — Sun, 30 Aug 2009 01:44:18 +0000

Cardiac CT angiography is new and popular field for non-invasive evaluation of coronary artery disease or blocks in the blood vessels supplying oxygenated blood to the heart. With the introduction of 64 slice CT (computed tomography), the number of CT scanners in the cardiology sections of United State has increased three fold in the past two years. The high negative predictive value in those with low to intermediate risk of coronary artery disease has made this test very popular, but the risk of radiation and the potential risk of cancer may come up in the future years.

A recent study published in the Journal of American Medical Association by Jörg Hausleiter and associates and an accompanying editorial discusses this issue. They found that the radiation dose varied widely between different systems and centres. Modalities to reduce radiation dosasge did not significantly reduce the image quality. Hence they recommend the use of effective strategies to reduce the radiation dose in order to bring down any potential future risks.

64 slice CT accurately predicts presence and severity of coronary artery disease

Johnson Francis — Mon, 01 Dec 2008 17:17:00 +0000

64 slice CT angiography accurately predicts presence and severity of coronary artery disease, says a recent study published in the New England Journal of Medicine. The study by Julie M. Miller and colleagues from Johns Hopkins University School of Medicine and 8 other centres spread over 7 countries concluded that CT angiography accurately identifies the presence and severity of significant coronary artery disease (more than 50% narrowing) and subsequent revascularization (angioplasty or bypass operation) in symptomatic patients. The sensitivity of the test was 85% while specificity was 90%. The positive predictive value was 91% while the negative predictive value was lower at 83%. These values indicate that CT angiography cannot replace conventional coronary angiography at present. It is noteworthy that two patients had significant reactions to contrast medium used for CT angiography. The study involved direct comparison of 64 row, 0.5 mm CT angiography with conventional coronary angiography in 291 patients with calcium scores of 600 or less.

How is embolisation of an artery done?

Johnson Francis — Sun, 16 Nov 2008 05:53:54 +0000

First an angiogram is done by injecting the main artery with iodinated contrast to visualise the origin of the target vessel from the main vessel. The arteries can be approached either through the groin or wrist by introducing small tubes known as catheters under local anaesthesia. Once the origin and distribution of the target vessel to be embolised is found out by angiography, a guide catheter is introduced and parked in the target branch. If the target vessel is quite small, a micro catheter can be introduced through the guide catheter and tip localised at the region of interest. Once it is in position, either gel foam or coils can be delivered to produce embolisation and vessel closure. If liquid material is being introduced, as in case of alcohol septal embolisation in hypertrophic cardiomypothy, it is necessary to occlude the parent artery (left anterior descending coronary artery in this case) prior to delivery of the agent to prevent it from spilling over to the parent artery and causing extensive damage. Bronchial arteries are embolised to prevent severe and recurrent hemoptyis (spitting of blood). Sometimes the uterine artery is embolised to prevent recurrent and severe uterine bleeding. Major aortopulmonary collateral arteries can be embolised along with surgical correction of Tetralogy of Fallot.