WEDNESDAY MORNING, MAY 13, 1981

8:30 A.M. Scientific Session - International Ballroom

(Forum Papers)

27. Computerized Fluoroscopy-A New Technique for the Noninvasive Evaluation of the Aorta, Coronary Artery Bypass Graft Patency, and Left Ventricular Function

P. DAVID MYEROWITZ*, ANDREW B. CRUMMY*,

DAVID L. ERGUN*, CHORNG-GANG SHAW*,

PARAMJEET S. CHOPRA, HERBERT A. BERKOFF*,

GEORGE M. KRONCKE*, GEORGE G. ROWE*,

CHARLES A. MISTRETTA * and WILLIAM D. TURNIPSEED*,

Madison, Wisconsin

A computerized fluoroscopy system (C.F.) has been developed based on real time digital processing of x-ray transmission data from traditional image-intensified fluoroscopy equipment. High quality visualization of any part of the arterial system is obtained following intravenous injection of 0.5 to 0.75 ml/kg of iodinated contrast materials. Previous reports from this institution have outlined the usefulness of C.F. for visualizing carotid, peripheral, and renal arteries following intravenous contrast injections. This report describes the use of this technique to evaluate the aortic arch, left ventricular function, and coronary artery bypass graft patency. Fifty intravenous studies were performed in 25 patients. Among 20 patients with coronary artery bypass grafts, C.F. correctly identified 11 of 15 patent grafts and 11 of 11 occluded grafts as confirmed by standard coronary arteriography in 11 of these patients. Unlike computerized tomography, our technique gives a longitudinal view of the bypass graft much like direct coronary angiography. Aortic arch studies included demonstration of a right aortic arch with a small left subclavian artery, a coarctation, and a normal aortic arch in a trauma patient with a wide mediastinum. Segmental wall motion abnormalities have been clearly identified by a modification of the technique which produces a negative outline on the ventriculogram in dyskinetic segments. Ejection fractions may be calculated by analyzing the amount of iodine in the ventricle in systole and diastole. This technique may also be used to evaluate carotid disease in patients undergoing coronary artery bypass surgery. C.F., therefore, allows evaluation of the entire cardiovascular system by the relatively noninvasive technique of intravenous angiography.

*By invitation

28. Establishment of Right Ventricle to Hypoplastic Pulmonary Artery Continuity Without the Use of Extracorporeal Circulation: A New Surgical Technique

FRANCISCO J. PUG A * and GIDEON URETZKY*,

Rochester, Minnesota

Sponsored by: Dwight C. McGoon, Rochester, Minnesota

A technique that allows establishment of continuity between the right ventricle and hypoplastic pulmonary confluence without the use of extracorporeal circulation in patients with pulmonary atresia and ventricular septal defect has been applied successfully in the laboratory and in four consecutive patients. Exposure is achieved by an anterolateral thoracotomy through the left third intercostal space. A Dacron tubular graft of appropriate size is anastomosed to the hypoplastic but confluent pulmonary artery bifurcation. A fine, stranded, multifilament steel wire is passed through the anterior wall of the outflow portion of the right ventricle so that a two to three centimeter loop lies in the right ventricular cavity. The proximal end of the nonvalved tubular graft is anastomosed to the epicardial surface of the right ventricle around the exit points of the wire. The ventricular incision is achieved by sawing through the right venricular wall with the wire in a manner similar to a Gigli saw. No systemic heparinization is used. The characteristics and adequacy of the right ventriculotomy were studied on the right ventricular outflow tract of two dogs, while a third animal was remained alive and well up to two months after undergoing the procedure in addition to interruption of its main pulmonary artery. Four consecutive patients, ages 22, 12, 8 and 2 years, have undergone this procedure. All had confluent but hypoplastic pulmonary arteries measuring 6, 5, 5 and 3 mm. in diameter. There were no surgical deaths. Average blood loss was 200 cc. and all patients showed an increase in peripheral arterial oxygen saturation. All patients underwent postoperative cardiac catheterization and angiography. All patients had patent conduits and pulmonary arteries which had increased in diameter. Advantages of the procedure are: avoidance of the median sternotomy which may simplify future closure of the VSD; simplification of an effective technique which under extracorporeal circulation is complicated by profuse collateral flow that tends to obscure the operative field and distend the heart; minimal bleeding resulting from avoidance of systemic heparinization which in these severely cyanotic patients can lead to severe bleeding diathesis; and, hopefully, a decrease in the risk of this type of reconstruction.

*By invitation

29. Successful Orthotopic Canine Heart Transplantation After 24 Hour In Vitro Preservation

ALBERT J. GUERRATY*, PETER A. ALIVIZATOS*,

MARK W. WARNER*, MICHAEL L. HESS* and

RICHARD R. LOWER, Richmond, Virginia

Prolonged in vitro preservation of donor hearts may be of importance in the future expansion of clinical cardiac transplantation to extend the distance over which donor hearts may be transported and to allow for more extensive preoperative histocompatibility testing.

A protocol was developed to provide continuous, hypothermic, nonpulsatile perfustion with an oxygenated balanced electrolyte solution for preservation of the isolated canine heart during 24 hours prior to orthotopic transplantation. Important features of the cardiectomy technique include the use of a calcium channel blocker, potassium arrest and rapid cooling of the myocardium. The donor heart is then perfused at a pressure of 18-22 cm. of water and at an average flow of 75 cc/mm/100/gm. of tissue. The septal temperature is maintained at 5-7°C and the perfusate pH at 7.25-7.35. Subcellular function after 24 hours of perfusion and transplantation, as assessed by sarcoplasmic reticulum and myofibrilar ATPase activity were not significantly different from control values.

Two groups of mongrel dogs were studied after orthotopic transplantation: Group I (N= 15) received hearts perfused by the above protocol for 24 hours and Group II (N = 9) received hearts removed by the same cardiectomy technique, but transplanted immediately. All grafts functioned well initially with support of the circulation after bypass. Eleven animals in Group I survived 4 days to 2 months and six animals in Group II survived 4 days to 3 weeks postoperatively. Measurements of heart rate, cardiac output, pulmonary capillary wedge pressure, left ventricular pressure and peak developed left ventricular pressure, before and after dobutamine infusion, were normal in all animals and there were no statistical differences between Group I and Group II animals.

Thus, a reliable and reproducible method for 24-hour in vitro perfusion of the canine heart has been obtained and should be applicable in clinical cardiac transplantation, when periods of preservation for longer than a few hours are required.

*By invitation

30. Prostacyclin Infusion During Cardiopulmonary Bypass - Clinical Experiences

KJELL RADEGRAN* and

CHRISTOS PAPACONSTANTINOU*, Gothenburg, Sweden

and Saloniki, Greece

Sponsored by: David P. Hall, Chattanooga, Tennessee

Prostacyclin is an integral part of the body's defence against platelet aggregation and intravascular coagulation. It has been shown in experimental studies on dogs to preserve platelet number and function during cardiopul-monary bypass (CPB). The present study reports our initial experiences with prostacyclin infusion during CPB in man.

The study comprises 74 adult patients operated for acquired heart disease during the period June 1979 - June 1980. CPB was by roller pump and bubble oxygenator primed with a crystalloid solution. Moderate hypothermia was used in all cases. Heparin was given in a dose of 3 mg/kg b.w. Anticoagulation was checked by activated clotting time measurements (ACT). Twenty-eight patients serving as controls did not receive prostacyclin. Ten patients were infused with prostacyclin 2-20 ng/kg/min throughout the CPB period, while twenty-two patients got 50 ng/kg/min for the first 30 min of CPB only and fourteen patients got 100 ng/kg/min from start of CPB until 5-20 min before termination of CPB.

Results: Infusion of prostacyclin 50-100 ng/kg/min resulted in a consistent protection of the platelet count. Even after 2 hours of bypass when in the control group the platelets had decreased to 70 ± 14% (x ± S.D.) of pre-CPB value, corrected for hemodilution, the platelet count was in the 50 and 100 ng groups resp. 93 ± 17 and 102 ± 20%. This difference remained also one hour after CPB when protamine had been administered. The high dosages of prostacyclin had pronounced effects also on arterial pressure and systemic vascular resistance (SVR) during CPB. During hypothermia the arterial pressure was in average around 20 mm Hg and the SVR was reduced to less than half of that in the control group. Prostacyclin, 50-100 ng/kg/min also prolonged the ACT to more than 1000 sec as compared with 544 ± 117 sec in the control group.

There were three deaths among the 28 control patients and 2 deaths among the 46 patients infused with prostacyclin. There was one instance of reversible hemiplegia in the control group and one among the prostacyclin patients, both in patients with aortic valve replacement.

No difference in intraoperative blood loss was observed between control and prostacyclin patients. In the postoperative period prostacyclin patients bled on an average about 25% less than control patients, i.e. 580 ± 250 versus 810 ± 450 ml.

*By invitation

31. Four Year Clinical Experience With the Gelatine-Resorcine-Formol Biological Glue in Acute Aortic Dissection

JEAN E. BACHET*, CLAUDE LAURIAN*,

OLIVIER BICAL*, BERTRAND GOUDOT* and

DANIEL GUILMET*, Suresnes, France

Sponsored by: Charles DuBost, Paris, France

From Jan. 1977 to Sept. 1980, the Gelatine-Resorcine-Formol (G.R.F.) biological glue was used for tissue reinforcement in 25 patients operated on for acute dissection involving the ascending aorta.

The results of these patients (GRF group) were compared to results of 25 patients operated on between 1970 and 1976 with "classical techniques" (CT group). There were no significant differences between the 2 groups regarding the age, the preoperative clinical and anatomical data.

The ascending aorta was replaced in all patients; the aortic valve was replaced twice (8%) in the GRF group and in 12 cases (48%) of the CT group the coronary arteries were by-passed or reimplanted in 20% patients of each group. Average intra-operative blood transfusion volume was 5800 ml in the CT group and 2100 in the GRF group (p 0.01). Four (16%) preoperative deaths were registered in the CT group and none in the GRF group.

Postoperative renal failure, cerebral ischemia, persisting peripheral ischemia and infection were more frequent in the CT group. They were responsible for 8 hospital deaths in this group and for two in the GRF group (p 0.01). Hospital mortality was therefore reduced from 48% (CT group to 8% (group GRF) (p 0.01) 2 late deaths were registered in the CT group and none in the GRF group, all survivors being in good clinical condition.

Sixteen patients of the GRF group underwent 19 control angiograms, 2 to 36 months following surgery, which documented 2 moderate aortic incompetence (8%), 3 persisting dissections of the descending aorta, but good and stable repair in the other patients.

In conclusion, the use of the GRF glue significantly reduce:

- the number of aortic valve replacements;

- the intra and postoperative bleeding;

- the frequency and severity of postoperative complications.

Therefore, long-term (4 years) survival rate has been raised from 40% to 92%.

*By invitation

32. In-Vitro Assessment of Anti-Neoplastic Therapy: A New Indication for Thoracotomy

LARRY R. KAISER*, E. CARMACK HOLMES and

DAVID KERN*, Los Angeles, California

Selection and determination of the efficacy of antineoplastic agents has been dependent upon the trial and error method of observing measurable disease. Such methods not only subject the patient to loss of precious time, but to needless toxicity if the drug is ineffective. The clonogenic assay, a technique for evaluating the patient's response to neoplastic agents, has been developed which has the potential for individualizing therapy. In this assay, tumor cells exposed to various drugs are cloned into colonies. Of the 14 primary and 17 metastatic pulmonary tumors tested with this technique, a growth rate of 80-85% was achieved. Fifty percent of the primary tumors and 60% of the metastatic lesions responded in vitro to one or more of the test drugs. The correlation between in vitro and in vivo response was 60%. No drug that was inactive in vitro had activity in vivo. Prior knowledge of in vitro sensitivity may dictate a more aggressive surgical approach to pulmonary metastatic disease, whereas in vitro resistance would call for more conservative treatment. Just as with estrogen receptor status in breast cancer, data derived from the clonogenic assay may ultimately be of such import that thoracotomy would be warranted solely for the purpose of obtaining tissue for the assay.

*By invitation

33. An Endobronchial Blocker for One-Lung Anaesthesia

ROBERT JASON GINSBERG, Toronto, Ontario, Canada

One-lung anaesthesia is a valuable adjunct in the conduct of pulmonary and esophageal anaesthesia. The standard technique for one-lung anaesthesia employs a double-lumen endotracheal tube (Robertshaw, Carlens). These tubes have many disadvantages. A simpler method has been developed. All that is required is an 8-14 Fogarty occlusion catheter, a fiberoptic bronchoscope and a standard cuffed endotracheal tube.

After induction of the anaesthetic, the Fogarty catheter is passed through the larynx into the lower trachea and, then, the endotracheal tube is inserted. Using the fiberoptic bronchoscope, the tip of the Fogarty catheter is positioned in either main-stem bronchus under direct vision. The cuff of the endotracheal tube is then inflated, fixing the catheter in position. One-lung anaesthesia can then be accomplished simply by inflating the balloon of the Fogarty catheter.

This method has been used in over 150 thoracotomies. It has always been successful with no complications except in right posterolateral thoracotomies where occasional dislodgement of the catheter can occur. The advantages of this method over the double-lumen tube include:

- Simple (no need for anaesthetic experise for insertion of a double-lumen tube).

- Applicable in small patients.

- More reliable and faster.

- Does not interfere with bronchial closure at the carina.

- It can be repositioned under direct vision any time during the operation, (although rarely necessary in our experience).

- It allows for large-bore endotracheal and endobronchial suctioning.

Because of its simplicity, this method has also been used as an adjunct to anterior mediastinoscopy, pleuroscopy and talc poudrage. It allows for total visualization of the pleural space during these diagnostic and therapeutic procedures.

34. The Relationship of a Hiatal Hernia to the Function of the Body of the Esophagus and Gastroesophageal Reflux

TOM R. DeMEESTER, LAWRENCE F. JOHNSON*,

EDWIN LaFONTAINE* and DAVID B. SKINNER,

Chicago, Illinois and Washington, D.C.

Sixty-nine patients referred to our esophageal function laboratory without endoscopic esophagitis were divided into two groups based on the presence or absence of a hiatal hernia on both a radiographic study and endoscopic examination. Fifty-one patients had a hiatal hernia and 18 patients did not have a hiatal hernia. Both groups had esophageal manometry, 24-hour esophageal pH monitoring and esophageal mucosal biopsy to evaluate the effect of a hiatal hernia on esophageal function. There was no difference in the length of esophagus exposed to the positive pressure environment of the abdomen between the two groups. Patients with a hiatal hernia had a statistically lower distal esophageal sphincter pressure (p<001), and calculated closing force of the cardia (length x pressure x 1.33 assuming a standard breadth of esophagus) (p<.01). The body of the esophagus in the presence of a hiatal hernia was less effective in clearing refluxed acid back into the stomach (p<.025). This occurred only in the supine position and not while upright, when gravity assisted clearance. These functional impairments were reflected by abnormal epithelial change (Pope's criteria), indicating mucosal damage by refluxed acid, and prolonged acid mucosal contact time in patients with a hiatal hernia (p<.025).

To determine if the inability of the body of the esophagus to clear acid in the presence of a hernia was due to the lack of anchoring the esophagus at its distal end to the lumbar spine as occurs normally, the pre and postoperative studies of 13 hiatal hernia patients who had a posterior abdominal gastropexy without imbrication of the cardia were reviewed. A significant improvement in esophageal clearance and amount of mucosal acid exposure over pre-operative levels was noted, indicating that anchoring the distal esophagus improved the ability of the body of the esophagus to clear its luminal contents (p<.05).

Conclusions: (1) The presence of a hiatal hernia was associated with poor esophageal clearance in the supine position, a reduced distal esophageal sphincter pressure, and a normal length of abdominal esophagus. (2) Patients with a hiatal hernia had more acid reflux into the esophagus than those without a hernia. (3) Reduction of the hernia and anchoring the distal esophagus corrected the clearance abnormality and reduced esophageal acid exposure. (4) The presence of a hiatal hernia with its detrimental effect on clearance by the body of the esophagus contributes to the pathologic effects of gastro esophageal reflux from an incompetent cardia.

*By invitation

35. Use of the Silastic Tracheal "T" Tube for the Management of Complex Tracheal Injuries

JOEL DAVID COOPER, THOMAS R. J. TODD*,

RIIVO ILVES* and FREDERICK GRIFFITH PEARSON,

Toronto, Ontario, Canada

This paper reports on the use of the silastic Montgomery "T" tube as a useful adjunct in 18 patients with complex problems requiring tracheal resection and reconstruction.

In five cases, the "T" tube was used to maintain a patent airway at a time when the general condition of the patient, or of the tracheal lesion itself, would not permit resection and reconstruction. In these five patients, the tube was in place for an average of 13 months before resection and primary anastomosis were undertaken.

In three cases with complicated subglottic strictures, the mucosa at the proximal resection line was unhealthy and the upper limb of the "T" tube was used to stent the subglottic airway postoperatively. The average duration of stenting in these cases was 13 months, and all were successfully ex-tubated. In an additional five cases, the "T" tube was inserted postoperatively when it was determined that a primary anastomosis was failing. Two of these five were subsequently successfully extubated, two died of unrelated disease, and one is still under treatment.

In the remaining five patients the tracheal pathology was considered unsuitable for resection and reconstruction and the "T" tube was used to maintain an airway. Following an average of 12 months of such stenting, four of the five were extubated and required no further treatment.

It is concluded that the Montgomery "T" tube is a valuable adjunct in the management of selected complex tracheal problems. In subglottic lesions the upper limb of the tube may be positioned between the vocal cords, and yet these patients maintain a functional voice and aspiration has not been a problem. Furthermore, cord function was normal upon extubation. Since humidification is through the normal route, crusting and obstruction of the tube does not occur and the tubes can be left in place for long periods without the need for change.

INTERMISSION - VISIT EXHIBITS

*By invitation

MYOCARDIAL PRESERVATION SYMPOSIUM

Moderator: Quentin R. Stiles

Discussor: John W. Kirklin

36. Myocardial Damage Caused by Keeping pH 7.4 During Systemic Deep Hypothermia

HEINZ BECKER*, JAKOB VINTEN-JOHANSEN*,

GERALD D. BUCKBERG, JOHN M. ROBERTSON* and

JERRY D. LEAF*, Los Angeles, California

With rare exception, hypothermia is routine during cardiac operations and pH (measured at 37°C) is kept at 7.4. This clinical constraint does not occur in nature where poikilotherms vary blood pH in concordance with a temperature dependent neutrality point of water. This study tests the hypothesis that keeping pH 7.4 during hypothermia produces a degree of myocardial damage and limitation of effectiveness of cardioplegic protection which is avoidable by appropriate pH management.

Methods: In 14 puppies, body temperature was lowered to 22°C with surface hypothermia, then to 17°C with extracorporeal circulation. During 60 minutes of circulatory arrest all hearts were protected with the same miltidose K + cardioplegic solution. In 7 dogs, pH was kept at 7.4 and in 7 others pH was varied as in poikilotherms (i.e. 7.9 at 17°C) principally by adjusting pCO₂ during cooling and rewarming.

Results: During surface cooling, keeping pH at 7.4 caused inadequate cardiac output (hypotension, systemic lactic acidosis, 11 ± 5%production). Conversely, pH adjustment allowed 25%* higher cardiac output with normal systemic lactate metabolism. Cerebral blood flow at 22°C, pH of 7.4, pCO₂ 40 mmHg fell 75%* (from 26 ± 6 to 10 ± 3 cc/100/min); raising pH to 7.75 by lowering pCO₂ below 10 mmHg allowed twice as much cerebral flow (20 ± 6 cc/100gm/min*). Despite optimum myocardial protection with blood cardioplegia during circulatory arrest, postischemic myocardial performance was depressed 50% by keeping pH 7.4. In contrast, postischemic performance was normal when pH was varied appropriately during cooling and rewarming (stroke work index 0.62 vs 1.27 at 25 mmHg LAP)*.

Conclusion: Constraining pH to 7.4 during hypothermia causes a degree of myocardial damage and limitation of cardioplegic protection which is avoidable by adjusting pH the way poikilotherms do. These findings have major implication in the routine management of hypothermia during all cardiac operations.

*p .05

*By invitation

37. Does Topical Hypothermia Prevent Sublethal Intraoperative Injury During Coronary Artery Bypass Surgery

RODERICK W. LANDYMORE*, DAVID TICE,

NARESH TREHAN* and FRANK C. SPENCER,

New York, New York

Recent reports have suggested that myocardial protection is inadequate during coronary artery bypass surgery for severely diseased coronary arteries. Since methods of myocardial preservation vary considerably between cardiac centers, this study was designed to determine whether or not topical hypothermia is a necessary adjunct to systemic hypothermia and potassium cardioplegia during myocardial revascularization, in patients (pts) with diffuse coronary artery disease. Twenty-two pts ages 47-68 yrs were included in the study. Pts were placed on bypass and cooled to 28° centigrade (c). Temperature (temp) was measured over the right and left coronary distributions. The aorta was then cross-clamped and 1000cc of potassium blood cardioplegia 5.7-11°c (X 8.7) was infused into the aortic root at a pressure of 100-120 mm hg. Temp was measured and then 6 liters of cold plasmalyte 2.3-5.1°c (X 3.5) was poured over the heart into the pericardial well. Temp was again measured. In addition cold plasmalyte was continuously dripped over the heart during the cross-clamp.

*SEM + -Standard Error of The Mean

**Students T-Test P<0.01

Systemic hypothermia and potassium (K + ) cardioplegia uniformally failed to protect the myocardium in regions supplied by severely Stenotic or occluded arteries. The addition of cold topical reduced myocardial temperature to the safe operative range. This data demonstrates that combined systemic hypothermia and K+ cardioplegia alone do not provide adequate protection in pts with diffuse coronary disease. We conclude that the addition of topical hypothermia ensures adequate protection during coronary bypass surgery and recommend the routine use of intra-operative myocardial temp monitoring.

*By invitation

38. Myocardial Protection During Aortic Valve Replacement. Comparison of Different Methods by Intraoperative Coronary Sinus Blood Sampling and Postoperative Serial Serum Enzyme Determinations.

CHRISTIAN L. OLIN*, VOLLMER BOMFIM*,

LENNART KAIJSER*, CHRISTER SYLYEN* and

STELLAN STROM*, Stockholm, Sweden

Sponsored by: Viking J. Bjork, Stockholm, Sweden

Ninety-seven patients undergoing isolated aortic valve replacement were studied during operation by simultaneous blood sampling from the coronary sinus and brachial artery and after operation by serial determinations of myocardium specific serum enzymes. Myocardial protection was accomplished by selective coronary perfusion in 26 patients, hypothermic potassium cardioplegia in 38, single dose blood cardioplegia in 15 and continuous blood cardioplegia in 18 patients. The continuous blood cardioplegia method consisted of a slow pulsatile infusion of 15°C cold oxygenated blood from the heart-lung machine (with 20 mekv K+ and 16 mekv Mg + + per liter added) selectively into the left coronary artery during aortic cross-clamping. The intraoperative blood samples were analysed for PO₂, O₂-saturation, O₂-content, PcO₂, pH, lactate, pyruvate, glucose, potassium and myoglobin, the postoperative blood samples for creatine kinase (CK) its isoenzyme (CK-MB), and aspartate aminotransferase (ASAT, equivalent to S-GOT). Myocardial biopsies were taken from the left ventricle on commencement and termination of cardioplegia in the blood cardioplegia groups and analysed for adenosine triphosphate (ATP), creatine (C) and creatinephosphate (CP).

In the coronary perfusion group, one patient (4%) died of left ventricular failure due to ischemic myocardial damage and three (12%) needed vasopressor support postoperatively. In the three cardioplegia groups (71 patients), there was no mortality and none of the patients needed vasopressor support.

The metabolic studies showed that selective coronary perfusion failed to protect the myocardium completely in spite of high coronary flow. Ten minutes after bypass there was still a production of lactate by the heart. The metabolic pattern was similar in the three cardioplegia groups and was characterized by an early washout of lactate and other metabolic products, decreased oxygen extraction, increased potassium and myoglobin release. The CK-MB activity peaked between 3 and 4 hours after reperfusion. If the three cardioplegia methods were compared, the continuous blood cardioplegia method was the best. The metabolic changes were significantly smaller and normalized more quickly during reperfusion. Blood samples from the coronary sinus during cardioplegia showed that the heart extracted oxygen in spite of its relaxed state. The myocardial biopsies also showed significantly less ATP and CP decrease in the continuous blood cardioplegia patients.

*By invitation

39. The First American Clinical Trial of Nifedipine in Cardioplegic Solution for Myocardial Preservation: A Preliminary Report

RICHARD E. CLARK, IGNACIO Y. CHRISTLIEB*,

THOMAS B. FERGUSON, CLARENCE S. WELDON,

JOHN P. MARBARGER*, PHILLIP N. WEST*,

BUR TON E. SOBEL*, ROBER T ROBERTS*,

DANIEL R. BIELLO* and BARBARA K. CLARK*,

St. Louis, Missouri

A continuing prospective, FDA approved, clinical trial of high risk cardiac patients was begun in May, 1980 after five years of extensive evaluation in dogs of the efficacy of the addition of nifedipine, a calcium antagonist, to cold hyperkalemic cardioplegic solutions. Protocol patients received preoperative and postoperative (0-72 hrs., 1 and 6 wks) determinations of ejection fraction and wall motion by radionuclide ventriculography (4/pt), MB-CK isoenzyme (33/pt), myocardial pyrophosphate scans (≥2/pt) for evidence of biochemical and morphologic changes and extensive and frequent intra and postoperative hemodynamic measurements to assess functional status and six 24 hr. ECG recordings. Thirty-six patients have received nifedipine in cardioplegic solution, 21 within the protocol and 15 outside the protocol for emergent reasons. 28 of the 36 had Class III or IV severe left ventricular dysfunction and required single, multiple and/or re-placement valvular surgery (10), CABG (9) or a combination of both (9). During the same calendar interval, 37 patients with equally poor ventricular dysfunction and similar distribution of operations (5 within the protocol) have had cardioplegic solution (CPS) without nifedipine. The results to date are:

These preliminary results are reported because of the reduction in mortality, threefold decrease in use of IABP, and concordant data of functional, biochemical and morphologic improvement in nifedipine treated patients which will be reported. It is concluded that high risk patients with severe ventricular dysfunction who have been treated with nifedipine in cold cardioplegic solution have superior clinical outcomes in comparison to those treated with cold cardioplegic solution alone.

*By invitation

40. Preservation of Myocardial Ultrastructure and High Energy Phosphates in Humans

SAMUEL C. BALDERMAN*, JOGINDER N. BHAYANA*,

PAUL BINETTE*, ARTHUR CHAN* and

ANDREW A. GAGE*, Buffalo, New York

Sponsored by: Richard H. Adler, Buffalo, New York

To establish whether multidose crystalloid potassium hypothermia car-dioplegia provides adequate preservation of myocardial ultrastructure and high energy phosphates, 25 patients with EF of ≥50%, undergoing cardiac surgery were studied. Eight patients had three biopsies taken for ATP and CP determination from the left ventricular apex. Biopsies were taken immediately prior to aortic cross clamping immediately after the release of the aortic cross clamp and 30 minutes after the release of the cross clamp. Seventeen patients had six biopsies taken from the left ventricular apex at the above stated time. Three for ATP and CP determination and three additional biopsies for electron microscopy. One patient sustained a small perioperative infarction and another patient died on the 5th postoperative day from an aortic dissection. The mitochondria on the electron microscopic specimens were graded on a scale from 0 - 4 (4 = severe changes).

There was no significant difference in the mitochondial scores. The preservation of high energy phosphates was less complete. ATP was reduced to 78% of control and CP was reduced in the immediate post clamp period to 32% of control.

The differences are particularly significant if one looks at patients whose aortic cross clamp time was ≥90 minutes (12 patients). In this group, ATP and CP preservation was 71% (3.33/4.60 m moles/kg, wet weight) and 53% (1.48/2.81) respectively 30 min. after clamp removal. (p≤.01)

Conclusion: Hypothermic potassium cardioplegia gives excellent preservation of the myocardial ultrastructure in humans. However, the preservation of high energy phosphates with this technique is imperfect.

*By invitation