Usually, CABG is performed while the heart is temporarily stopped. During this period, its function is performed by the "Heart and Lung machine" ... a technique called cardiopulmonary bypass. This produces certain unavoidable ill-effects.
Technology and expertise have today developed to such an extent that surgeons can sometimes carry out the bypass operation even while the heart is beating. Since the heart and lung machine is no longer needed, the side effects are less.
However, the technical demands on the surgeon, who now has to precisely stitch together two blood vessels, each measuring about TWO to THREE MILLIMETERS in diameter, can be readily imagined. So when your surgeon presents you with a whopping bill for services, don't grumble....he deserves every cent !
This is the latest in CABG. Through incisions barely as long as your thumb, a coronary bypass operation can be done. As for any new development, the application is not universal, but only in select cases. Want to know more ? Visit the MIDCAB Forum.
With the recent trend to do CABG operations with the heart beating, different surgeons have varying ability in constructing perfect conduit connections. Work in experimental labs suggests that in the future it may be possible to design robots to perform these connections. Using video cameras and recordings of ECG traces of the patient, the robot predicts exactly where the artery will be at a given moment of time, and will be able to precisely stitch arteries together. Vive la Robots !
Susrutha, a famous Indian surgeon of ancient times, used ANTS (yes, I'm not kidding ! ) to close surgical wounds. After the jaws of the ant gripped the edges of the wound, he twisted off their heads.
Today, staplers do what ants did before....
CABG has been traditionally done with very fine thread, thinner than human hair. A stapling device is being experimentally tested to replace sutures in CABG. When perfected, this will considerably reduce time taken to make the connections between graft and coronary artery.
Sometimes, the coronary arteries are so badly blocked that it is impossible to find a healthy area on which a graft can be connected. What to do then ?
The answer to this perplexing question was found by another Indian surgeon (not so ancient, though) - DR.P.K.SEN - who used acupuncture needles to create tiny tunnels in the wall of the heart....as early as in 1963 ! Blood from within the heart cavity could now directly enter the tunnels and nourish the heart !
As so many discoveries from under-developed nations, this innovative technique was forgotten....only to be re-discovered in the 1990s. Now, however, it was with a new toy - LASER beams - rather than needles, that holes were punched into the heart wall. Called TRANSMYOCARDIAL LASER REVASCULARISATION (TMLR), the technique offers promise to those patients with so-called "UNGRAFTABLE" coronaries.
Cardiologists came up with the idea of scaffolding the coronary artery after opening it up. Still through their ubiquitous catheters, they implanted stents after dilation. Dozens of types of stents are used today....Gianturco-Roubin, Palmatz-Schatz, Wiktor, Strecker, Wallstent...and what have you. Each is different in a subtle way, but all do the job !
The ideal stent should remain in place till the artery becomes strong enough to remain open. After this, it becomes an unwanted guest in the lumen of the coronary. Recently, scientists have been able to design stents out of material that is degraded or absorbed after a few weeks or months in the body...they're called "Biodegradable Stents".
Its getting better and better, huh ? Well, as the Gipper said, "You aint seen nothin' yet !"
Just as doctors - cardiologists and surgeons - were patting themselves on the back on managing the "impossible" the spectre of RE-STENOSIS raised its ugly head.
Re-stenosis means a return of the narrowing process which had been so effectively relieved by angioplasty...and within a disturbingly short time too.
Current research is directed mainly towards preventing this, and already several exciting innovations have been suggested.
And you thought viruses only caused the 'flu ! Well, they still do. But when scientists get their teeth into them, and fool around with their genes, they become useful tools to be manipulated in many ways.
One such, which is going to be much talked-about soon, is GENE-TRANSFECTION. In simple terms, this means a human gene (which is a protein that carries information to a cell on what to do, and how to behave) can be modified and altered favorably, and then carried by a virus to a desired target cell in another human being. The technical term for this complex procedure is equally complex...ANTI-SENSE OLIGONUCLEOTIDE THERAPY ! Got it ?
Let me try and clear this up for you....We were talking about "re-stenosis", right ? What causes re-stenosis ? A gene in the coronary artery wall does. What can we do about it ? Well, we can identify the gene, modify it so that it no longer causes re-stenosis, load it into a virus, and inject it into man ! The virus would transfer the gene to the wall of the dilated coronary artery. Voila ! No re-stenosis ! Like it ? I sure do....
After drilling or burning or ballooning, a rough inner surface is left behind in the coronary artery. This irregularity will cause blood to clot, and will also produce re-stenosis later. A novel method to avoid this is to smoothen the inner lining. How ? By a technique called
POLYMERIC ENDOLUMINAL PAVING....
A polymer which is liquid, but hardens at body temperature, is injected through a catheter into the artery which has been balloon-dilated, and pressed against the wall till it hardens. The inner lining is now smooth, and clotting and re-stenosis are prevented....Atleast that's what we hope, the procedure is still experimental.