Evaluation of venous bypass grafts from aorta to coronary artery by inert gas desaturation and direct flowmeter techniques.

Blood flow through aorta-to-coronary artery bypass grafts has been measured selectively in 16 patients at or within 6 wk after operation. Inert gas desaturation curves were obtained from coronary venous blood samples after a 7-15 min infusion of dissolved H(2) directly into the graft. Samples were analyzed chromatographically and curves resolved to 1-3% of initial H(2) concentrations. Average flow per unit volume (F/V) was 67+/-21 (sd) ml/min per 100 g. Semilogarithmic plots showed F/V to be distributed heterogeneously in every case. In nine studies at operation, H(2) measurements of average F/V were combined with electromagnetic measurements of total flow to estimate revascularized tissue mass. Electromagnetic flows ranged from 25 to 170 ml/min and averaged 69 ml/min. Tissue mass ranged from 46 to 155 g and averaged 88 g. We conclude that bypass grafts provide nutritive flow to significant amounts of myocardium at and shortly after operation. However, nutritive flow is not distributed evenly throughout the revascularized segment. The majority of the segment has a F/V within the accepted range of normal but there remain areas in which F/V is reduced significantly. The combination of inert gas and electromagnetic techniques allows a revascularized area to be characterized in terms of total flow, F/V, and tissue mass.

Influence of length of aortic occlusion with cold potassium cardioplegia on early and late mortality in cardiac valve replacement.

This study determines if prolonged aortic crossclamp time (ACC) with the use of cold potassium cardioplegia during elective cardiac valve replacement contributed to the risk of operative mortality in 225 patients. In Group I (143 patients), the ACC was less than 120 minutes (mean 86) and in Group II (82 patients), it was greater than 120 minutes (mean 146). The preoperative variables showed that Group II contained more severely ill patients who were undergoing more complex operations than in Group I. The operative mortality rate was 7% in Group I and 10% in Group II (p = not significant). Postoperative inotropic support was required in 13% of Group I and 30% of Group II patients (p less than 0.005). Operative mortality in patients in New York Heart Association (NYHA) functional class I and II was 0 and in patients in classes III and IV it was 13% (p less than 0.00008). Five percent of patients in NYHA classes I and II and 32% in classes III and IV required inotropic support (p less than 0.000005). The actuarial survival at 60 months was 88 +/- 3% for Group I and 77 +/- 7% for Group II (NS). For the NYHA class I and II patients, however, it was significantly better (98 +/- 2%) than class III and IV patients (75 +/- 5%) (p less than 0.0001). Analysis by logistic equation revealed that the NYHA functional classes III and IV were significant incremental risk factors for probability of in-hospital mortality (p less than 0.0001) but not the ACC time (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Dacron patch enlargement of anterior wall of left ventricle after aneurysmectomy with concomitant infarctectomy.

The basis for left ventricular aneurysmectomy with cardiopulmonary bypass was established 20 years ago. There is a higher risk in patients who undergo operation within 2 months of myocardial infarction. In these patients there may be no clear demarcation between devitalized tissue and residual healthy myocardium. A case is reported in which anterolateral aneurysmectomy with concomitant infarctectomy so compromised left ventricular size that the anterolateral wall of the left ventricle had to be reconstructed with a Dacron patch graft.

Combined antegrade/retrograde cardioplegia for myocardial protection: a clinical trial.

The role of retrograde coronary sinus perfusion in the preservation of ischemic myocardium is controversial. We evaluated the use of combined antegrade and retrograde cardioplegia in 59 patients undergoing coronary artery bypass surgery. Nineteen patients were administered antegrade cardioplegia, whereas 40 patients were administered antegrade plus retrograde cardioplegia. Hemodynamic data were obtained before the onset of cardiopulmonary bypass and at 1, 2, 4, 8, 16, and 24 hours after cessation of cardiopulmonary bypass. Myocardial function was assessed by measuring systemic blood pressure, heart rate, cardiac index, pulmonary artery pressure, and capillary wedge pressure. Both cohorts were similar in age, incidence of hypertension, diabetes, and previous myocardial infarction. No significant differences were noted in the need for postoperative inotropic support, the incidence of postoperative arrhythmias, myocardial infarction, heart block, or death. The two groups were similar with respect to cardiac index and systemic and pulmonary vascular resistance. However, the left ventricular stroke work index, when expressed as a function of its prebypass control value, was significantly improved (p less than 0.01) in the cohort administered combined cardioplegia. In the combined group recovery of left ventricular stroke work index occurred earlier and was more complete. These results suggest that the use of combined antegrade/retrograde cardioplegia is safe and may provide superior protection.

Total excision of the sternum and thoracic pedicle transposition of the greater omentum; useful strategems in managing severe mediastinal infection following open heart surgery.

Mediastinal sepsis following open heart surgery is a significant cause of death. Open drainage of the mediastinumalone was employed originally in management of this problem. More recently, debridement, drainage, and reclosure have been used. Various irrigation solutions, such as antibiotics and Betadine, have been advocated to control severe mediastinal sepsis. Three principles of management in patients unresponsiveness to the above techniques have proved successful in two patients with life-threatening mediastinal sepsis: (1) radical, complete excision of the sternum and adjacent costal cartilages; (2) transposition of the greater omentum on a vascular pedicle to the mediastinum; and (3) primary closure with full-thickness rotational skin flaps. The radical excision of the sternum removes residual foci of sepsis in cartilage and sternal bone marrow. The transposition of the omentum provides a highly vascular, rapidly granulating covering for the contaminated great vessels and hase been successfully to prevent recurrence of suture line bleeding of an exposed ascending aortic anastomosis site. Primary closure of the wound with full-thickness skin flaps provides a suprisingly satisfactory covering for the heart. Preoperative and postoperative measurements of ventilatory mechanics have shown relatively small ventilatory impairment after the alteration of the thoracic cage imposed by excision of the sternum. Two patients have returned to active lives. A treatment failure probably due to incomplete adherence to these guidelines also is presented.

Selective intracavitary and coronary hypothermic cardioplegia for myocardial preservation.Clinical, physiologic, and ultrastructural evaluation.

Intraoperative myocardial protection was evaluated in two groups of patients undergoing coronary surgery in whom different techniques for cardiac arrest were utilized. In group A, profound selective myocardial hypothermic (15 to 18 C) arrest was achieved by perfusing a coolant (7 to 10 C) into the left ventricular cavity and the coronary circulation. The average anoxic arrest time was 82.5 +/- 27 minutes. In group B, ventricular fibrillation and moderate hypothermia were used. Group A patients showed rapid physiologic recovery, low average myocardial creatinine phosphokinase (MB-CK) isoenzyme levels (7.8 IU) , and a well-preserved myocardial ultrastructure. In group B, three patients showed abnormal physiologic recovery; six patients needed postoperative inotropic support; and in seven patients, electron-microscopy revealed irreversible focal changes. The average MB-CK isoenzyme level was 85.6 IU. Analysis of our data demonstrates that when myocardial protection during coronary bypass grafting is achieved by selective profound intracavitary and coronary cooling, there is physiological, ultrastructural, and biochemical evidence of less intraoperative myocardial damage than when ventricular fibrillation is applied.

Free internal mammary artery graft. An improved surgical technique.

An improved method of free internal mammary artery (IMA)-to-ascending aorta anastomosis for cornoary bypass is described. We interposed a small patch of vein with a suitable side-branch or brancyes in connecting the proximal end of a detached IMA or radial artery. Thirty-four free IMA-to-coronary artery bypasses were performed in 25 patients; 16 right IMA, 14 left IMA, and 4 radial arteries were used. Cornoary angiographic follow-up studies performed in all patients between two weeks and six months after operation proved that all grafts were patent and showing a larger lumen than is usually seen in undetached IMA grafts. Concomitantly marked relief of anginal pain was noted in all patients. Oour experience with this technique is very encouraging. All patients are being followed to evaluate long-term graft patency.

Decompression of the heart with siphon drainage.

A simple technique for inducing intracavitary hypothermic cardioplegia and decompressing the left heart through the ascending aorta is presented. The technique is based on siphon drainage, which eliminates the dangers of air embolism.

Cold blood--potassium cardioplegia.

A technique is described for providing myocardial protection utilizing oxygenated blood that is drawn from the pump oxygenator and passed through two disposable cardioplegic cooling coils, which are joined in series and submerged in ice slush. A potassium-containing cardioplegic solution is run into the oxygenated blood at the level of the cooling coils. The amount of blood used in the blood-potassium cardioplegic mixture is controlled using a screw clamp. This method has been used with excellent results in 150 consecutive patients undergoing aortocoronary saphenous vein bypass grafting.

Selective intracavitary and coronary profound hypothermic cardioplegia for myocardial preservation: a new technique.

A technique is described for selective intracavitary and coronary hypothermic perfusion during cardiac bypass with cardioplegia to facilitate cardiac operations. A cold perfusate (Plasmalyte 148 and mannitol, 12.5 gm/L at 8 degrees to 10 degrees C) is administered with the aid of a low-flow perfusion pump into the left ventricular cavity and coronary circulation through an apical perfusion-venting (Per-Vent) catheter. This perfusate cools the myocardium rapidly and homogeneously to a temperature of 15 degrees to 20 degrees C. Within this temperature range, complete cardioplegia occurs and the safe ischemia period can be extended to 120 minutes. This method was applied in 50 unselected consecutive adult patients undergoing aortocoronary saphenous vein bypass grafting or aortic or mitral valve replacement. All patients survived and had excellent recovery of ventricular function.

Early and long-term effects on direct myocardial revascularization on cardiac function: a prospective study using multivariable physiological analysis.

Perioperative and late follow-up hemodynamic cardiovascular studies to assess the effects of direct myocardial revascularization on cardiac function objectively have been completed on 51 patients. Analysis of the data delineated three distinct groups basedon the patterns of their early postoperative recovery. Group I patients (12) had a hyperdynamic cardiovascular response to operation and returned to a normal physiological range of cardiac function within 24 hours. Group II patients (24) initially had moderate to severe myocardial decompensation postoperatively but responded to inotropic support and moved into the normal physiological range within 24 to 48 hours. Group III patients (15) had severe, prolonged myocardial decompensation with little response to inotropic support. There were no early deaths in Group I, 1 early iatrogenic death in Group II, and 2 deaths from sepsis, 1 in Group I and 1 in Group II. All 7 cardiogenic deaths occurred in Group III patients. Late follow-up studies 4 to 23 months postoperatively have been completed on 29 patients. These showed cardiovascular stability in the mean values in Groups I and II. Significant improvement in mean cardiac function was seen in surviving Group III patients.

Improved cardiovascular hemodynamics with atrioventricular sequential pacing compared with ventricular demand pacing.

To determine the advantages of atrioventricular (AV) sequential pacing over ventricular demand pacing, paired cardiovascular hemodynamic studies were performed in each pacing mode at a constant heart rate. The paired studies included determination of ejection fraction (EF) by echocardiography and gated blood pool radionuclide scanning, and of cardiac output (CO) by the indicator-dilution method. There was no significant difference in EF with either pacing mode. Determined by echocardiography, EF with AV sequential pacing was 57% compared with 56% with ventricular demand pacing; by the gated blood pool method, EF with AV sequential pacing was 58% compared with 57% in the ventricular mode. Significant improvement with AV sequential pacing was seen in CO (4.75 L/min from 3.75 L/min; p less than 0.01); stroke volume (58 ml from 48 ml; p less than 0.02); arteriovenous oxygen content difference (4.9 vol% from 5.6 vol%; p less than 0.01); total peripheral resistance (1,724 dynes sec cm-5 from 2,025 dynes sec cm-5; p less than 0.01); and cardiac contractility, as reflected by mixing time (6.9 seconds from 8.0 seconds; p less than 0.02). No significant changes were noted in mean arterial or atrial pressure or in systemic oxygen consumption. In a second group of 6 patients, similar paired studies were done in AV sequential pacing modes before and after therapeutic reduction of total peripheral resistance. A significant increase in CO (43%) was observed following reduction in total peripheral resistance. We conclude that AV sequential pacing improves CO more effectively than ventricular demand pacing. Cardiac output can be further enhanced in patients with congestive heart failure by pretreatment with agents to reduce total peripheral resistance.

Detection of creatine kinase BB isoenzyme in sera of patients undergoing aortocoronary bypass surgery.

Creatine kinase BB isoenzyme (CK-BB) was detected intraoperatively in 22 of 25 patients undergoing aortocoronary bypass surgery, both in the coronary sinus and in the mixed venous blood. In a group of 10 patients in whom selective intracavitary profound hypothermic arrest was used, CK-BB values were lower than in another group of 10 patients, in whom controlled ventricular fibrillation with moderate total body hypothermia was instituted. This latter group also had higher levels of CK-MB. Patients who developed acute myocardial infarction immediately prior to or during the surgical intervention had the highest CK-BB values. This enzyme appeared as early as 15 minutes after the institution of cardiopulmonary bypass and disappeared within 6 hours. It is considered that part of the BB isoenzyme in serum of patients undergoing heart surgery is of myocardial origin.