ATRIAL SEPTAL DEFECT :
|
Illness is older than man. The ancient Babylonians knew of congenital heart diseases even as early as 3800 BC. But the fate of these patients was very much the same as it would be for the next fifty five centuries. Rokitansky in 1875 first described defects of the atrial septum, but it was not until seventy five years later that operations to close them were attempted.
The evolution, ever since, of methods to treat Atrial Septal Defects (ASD) is a microcosm of progress in cardiac surgery as a whole. This article attempts to trace its fascinating path.
An important preliminary to attempting closure of ASD was the development of laboratory models to mimic the clinical situation. Once methods for thoracic exploration in general became understood, and tolerable cardiac manipulations delimited, attempts to create experimental preparations were soon successful.
It was found that simple incision or small excision of the interatrial septum (IAS) promptly healed. Blalock and Hanlon developed a method of atrial septectomy, in which the posterior IAS was removed. Using the inflow occlusion principle in animals, Swan and colleagues created large defects in the mid atrial septum by direct vision excision. Other methods of creating defects in the IAS were devised by Hufnagel, Donald and Gross.
Operations to close ASDs were first tried out on such artificially created defects in experimental animals. Their success encouraged surgeons to attempt correction on humans. Some of these procedures were crude. Others were more refined, and with few modifications are in use in some centres even today. But all of these repairs are remarkable because they were necessarily "blind" procedures, guided only by touch and carried out on a beating heart. They are a testimonial to the daring and imaginativeness of the cardiac surgeon of those times.
COHN in 1947 first attempted experimental closure of ASDs in dogs. The lateral right atrial wall was invaginated and stitched to the ASD margins. Using a tonsillar snare, the inverted atrial muscle was then detached to form a patch covering the defect.
In 1948, MURRAY reported the first closure of an ASD in a 12 year old child by an extracardiac method. A large suture introduced to the right of the aorta and pulmonary artery, passed through the upper edge of the ventricular septum and was tied down in a previously developed plane between the SVC and right pulmonary veins, thus squeezing the entire IAS.
SONDEGAARD further developed this technique and advocated dissection in the groove between right atrium and the right pulmonary veins.
DODRILL in 1949 devised a clamp that excluded a central part of the right atrium by approximating its wall against the septum. This area could be opened, the ASD inspected and then closed. This was the first time a procedure under direct vision of the IAS could be envisaged.
SWAN (1950) closed experimental ASDs by invagination of both auricular appendages tied over a stiff polythene disc, and later adapted the procedure for clinical use. It was shown that the "doughnut lumen" of the right atrium thus created did not interfere with blood flow between the vena cavae and tricuspid valve.
On May 6th, 1950, a nine year old patient was operated on at Colorado General Hospital using this principle. He has subsequently had successful open closure of a residual defect.
BAILEY described atrio-septo pexy where the right atrial wall was fixed by sutures to the margin of the ASD, guided by a finger through the right atrial appendage. SHUMACKER modified this procedure by attaching a pericardial or plastic sac to the auricular wall to maintain atrial cavity size. For posterior defects, GROSS and WATKINS found it easy to obtain closure by drawing the septal edge back to the posterior atrial wall using mattress sutures. GERBODE used a sharp hook with a slender shaft guided to the margin of the ASD by finger, to pull it into position where it was held by sutures.
In a variation of the patch technique, inert lucite buttons were used experimentally by HUFNAGEL and GILLESPIE to close ASDs. At surgery, two opposing buttons inserted through the atrial appendage using special rod introducers were tightly screwed together on opposite sides of the IAS. The brilliance of this concept is attested by the fact that it is used today in transcatheter closure of ASDs.
MARTIN and ESSEX stitched a polythene sheet over the defect and first described endothelialisation of the prosthesis.
Following this, a variety of prosthetic materials was tried out by many workers - DONALD, MILLER, POMERANZ, WATKINS, GROSS, BAHNSON and BAKER. They demonstrated that autogenous or homologous free tissue grafts are replaced by fibrous scars and that a variety of plastic materials are well tolerated and endothelialized.
A revolution of sorts was brought about in intracardiac surgery by the introduction of the "atrial well" technique by GROSS and WATKINS. The limited accessibility and reduced room for improvisation which had plagued earlier attempts at ASD closure were overcome. A rubber "well" was attached to the opened atrium, forming a pool of blood through which the fingers could be passed, allowing closure of defects guided by tactile direction.
However, every one of these procedures had its limitations and shortcomings. All of them were "blind", and did not permit study of the anatomy or allow for variations. Incomplete closure of large defects, inability to deal with associated anomalies and risk of accidental injury to adjacent vital structures were major drawbacks. Serious arrhythmias and interference with atrial blood flow during the procedure was a risk. Also, there was doubt with regard to healing of the apposed appendages to the edge of the ASD. Thrombus formation on the patch used to close the ASD was likely.
The 1940s was a very exciting decade in the development of cardiac surgery. The success of early operations in and around the heart encouraged a handful of bold surgeons to begin thinking seriously about operations within the open heart.
The wall of the heart had hitherto presented a seemingly impenetrable anatomic barrier to truly incredible possibilities. With the invention of apparatus which enabled direct visualisation of intra-cardiac structures, this barrier was safely breached. These methods have permitted the surgeon to empty the heart of blood, stop its beat, open any desired chamber and safely carry out reparative procedures in an unhurried manner. Surgery for ASD and for many complex intracardiac anomalies had truly come of age, and the older methods seemed relegated to a position of historic significance only.
Temporary interruption of blood flow through the heart was first described experimentally by HAECKER in 1907. It was not used clinically until SWAN in 1949 applied hypothermic inflow occlusion for the repair of ASDs. Under anaesthesia at 24 - 29 degrees C, inflow and outflow occlusion permitted wide opening of the right atrium to expose and repair the defect.
On September 2, 1952, JOHN F. LEWIS successfully closed a secondum ASD in a 5 year old girl using this technique. This date has historic significance because this was the world's first successful operation within an open human heart under direct vision, and ushered in a new surgical era. For the next few years, this was the accepted safe method of closing ASDs. The problem with this technique was the pressure on the surgeon to finish the operation within a short specified time.
On April 5, 1951, the first attempt to use the heart lung machine for total CPB in closure of a secondum ASD was made by DENNIS and colleagues, but the patient died of massive air embolism. JOHN GIBBON Jr. in May 1953, first successfully closed a secondum ASD in a young adult using extracorporeal circulation and total cardiopulmonary bypass. Gibbon however never was able to repeat his success and after 3 failures out of 4 procedures, did not use his machine again !
On March 26, 1954, C.W.LILLEHEI used controlled cross circulation as a means of total CPB for closing a VSD. This technique was however thought too complex for conditions like ASD which were being effectively treated by using inflow occlusion.
The next breakthrough was the development of a functional bubble oxygenator in 1955-56 by DE WALL, GOTT and LILLEHEI, which permitted routine performance of intracardiac corrections on the open heart. Ever since then, refinement of technology has made closure of ASDs using extracorporeal circulation the accepted surgical method of choice.
Open heart surgery allowed proper assessment of the anatomy of ASDs and choice of the corrective operation. The surgical principles adhered to were the use of CPB to allow unhurried technique, closure of the defect without tension, not compromising the atrio-caval orifice and re-routing any anomalous pulmonary veins. That these ideals were not always achieved is clear from the variety of repairs advocated.
Small atrial septal defects were closed by direct suture. In large defects, this may cause distortion of the atrial cavity and risk of venous obstruction. The use of a patch of autologous pericardium or a variety of prosthetic material was the logical solution.
While it solved many problems, the widespread use of CPB also opened up new vistas. Complexity of associated lesions needed suitable tailoring of the surgical procedure, utilising a spectrum of tissue flaps and prosthetic patches. The commonest of such conditions is anomalous pulmonary venous drainage, which could not be treated by closed heart surgery. The attempt to provide physiologic correction in these cases resulted in the mushrooming of operative procedures, which itself form the material for an extensive review.
Creative persons have ideas; only resourceful ones implement them. KING and MILLS, building upon the principles used in the days of closed heart correction of ASDs, in 1976 first reported transcatheter closure of a secondum ASD in humans with a double umbrella device in four out of five patients.
Basically, their occlusion device consisted of a skeleton of Teflon coated wire supporting an occluder of fabric (polyurethane foam, Dacron) delivered through a catheter. Improvements were quick to follow and mainly consisted of better device fixation methods and smaller caliber introducers.
RASHKIND used a hooked device to ensure more secure attachment to the left side of the atrial septum. LOCK developed a non-hooked Clamshell occluder which avoids endocardial injury and conduction system damage, both of which were drawbacks of the Rashkind device. It also allowed reversal of the procedure at all stages before release from the catheter.
Both of these devices required atleast 11 F introducer sheaths and contained all system components in the loading catheter.
SIDERIS and coworkers recently reported an ASD occluder requiring only an 8 F delivery system which could be used even in children weighing less than 8 kg ! Thus transcatheter techniques now became available to patients in all age groups.
The advantages of transcatheter closure techniques are a wide safety margin, no mortality (to date) and minimal morbidity. They avoid the need for thoracotomy, prolonged hospitalisation and intensive care. They are in fact even performed as outpatient procedures in some centres. The risk from postoperative hemorrhage, arrhythmias and post pericardiotomy syndrome is reduced.
However, pre procedure diagnostic catheterisation is mandatory in all cases to size the defect and left atrium and detect anomalous pulmonary connections. ASDs without a complete rim, or less than 4 mm. from vital intracardiac structures, and those with additional distal defects are unsuitable at present for transcatheter occlusion. Also, the number of cases and long term follow up are very limited.
Life is a circle, ending where it begins; so is the evolution of ASD repair techniques !
From no treatment at all, to closed heart operations, then open heart surgery, followed by transcatheter closure methods, therapy for ASD has become progressively simpler, safer and more complete. Just as cardiologists are patting themselves on the back on achieving a near perfect cure for ASDs, an interesting study questions the very need for intervention in asymptomatic patients with secondum ASDs, and advocates only regular follow up with echocardiography, reserving active treatment only for hemodynamic deterioration or asymptomatic cases !
This fascinating, and sometimes bewildering journey through time, recounting the evolution of ASD treatment methods evokes admiration for the dexterity and courage of cardiac surgeons, the innovativeness of cardiologists and the persistence and doggedness of research scientists.
BALLANTYNE JH
The Teratological Records of Chaldea
TERATOLOGIA 1894; 1: 127.
HUFNAGEL CA, GILLESPIE JF.
The closure of interauricular septal defects.
Bull. Georgetown Univ. Med. Center 1951; 4: 137.
DONALD DE, KIRKLIN JS, GRINDLAY JH.
The use of polyvinyl sponge plugs in the closure of large ASDs created experimentally.
Proc. Staff Meet, Mayo Clin. 1953; 28: 288.
GROSS RE, WATKINS E Jr, POMERANZ AA, GOLDSMITH EI.
A method for surgical closure of interauricular septal defects
SURG., GYNAEC. & OBSTET. 1953; 96: 1.
ROKITANSKY CF
Die Defect der Scheidewande desw Herzens.
Wilhelm Braunmuller, Vienna, 1875, p.153.
COHN R
An experimental method for the closure of interauricular septal defects in dogs.
AM. HEART J. 1947; 33: 453-457.
MURRAY G
Closure of defects in cardiac septa.
ANN. SURG. 1948; 128: 843-853.
SONDERGAARD T
Closure of atrial septal defects: Report of 3 cases.
ACTA CHIR. SCANDINAV. 1954; 107: 492.
DODRILL FD
A method for exposure of the cardiac septa. An experimental study
J. THORAC. SURG. 1949; 18: 652-660.
BAILEY CP, DOWNING DF, GECKELER GD et al
Congenital interatrial communications: Clinical and surgical considerations with a description of a new surgical technic: Atrio-septo-pexy.
ANN. INT. MED. 1952; 37: 888-920.
GERBODE FL
Discussion of Kirklin
J. THORAC. SURG. 1955; 29: 37.
GROSS RE, WATKINS E Jr
Surgical Closure of atrial septal defects.
ARCH. SURG.
SWAN H, MARESH G, JOHNSON ME, WARNER G.
The experimental creation and closure of auricular septal defects.
J.THORACIC SURG. 1950; 20: 542.
SHUMACKER HB Jr., MOORE TL, KING H.
The experimental closure of Atrial septal defects.
J.THORACIC SURG. 1953; 26: 551.
SWAN H, STEWART BD.
A modified button technique for closure of experimental inter auricular septal defects.
J.THORACIC SURG. 1953; 25: 397.
SONDERGAARD T.
Closure of atrial septal defects: Report of 3 cases.
ACTA CHIR. SCANDINAV. 1954; 107: 492.
BJORK VO, CRAFOORD C.
The surgical closure of inter auricular septal defects.
J.THORACIC SURG. 1953; 26: 300.
What's New ? DENCATS Home
This page hosted by
Get your own Free Home Page
