Levine Fh

Mitral valve replacement for isolated mitral regurgitation: analysis of clinical course and late postoperative left ventricular ejection fraction.

One hundred five patients underwent mitral valve replacement for relief of isolated mitral regurgitation between 1974 and 1979. There were 4 in-hospital deaths (4 percent) and 12 late deaths giving an 82 percent predicted 5 year survival rate. An age of 60 years or more at the time of surgery and a preoperative left ventricular ejection fraction of less than 0.40 were the only variables that correlated with decreased survival at 3 to 5 years after operation (p less than 0.05). Postoperatively, 87 (98 percent) of 89 long-term survivors were in New York Heart Association functional class I or II (68 in class I and 19 in class II). Survival did not differ between patients with porcine versus mechanical valve replacement, but patients with a mechanical valve had a greater incidence of postoperative cerebrovascular accident (8.6/100 patient years) than did patients with a porcine valve (2.8/100 patient years) (p less than 0.002). Ejection fraction at rest was determined with multigated cardiac imaging 12 to 75 months postoperatively in 34 of 89 long-term survivors. The mean preoperative ejection fraction was 0.62 +/- 0.09 (mean +/- 1 standard deviation) and the mean postoperative ejection fraction was 0.50 +/- 0.15 (p less than 0.001). When the preoperative value was compared with the postoperative value at rest the ejection fraction increased by 0.10 or more in 1 patient (3 percent), remained within +/- 0.09 of the preoperative value in 12 patients (35 percent) and decreased by 0.10 or greater in 21 patients (62 percent). Sixteen (94 percent) of 17 patients whose postoperative ejection fraction was greater than 0.50 were in functional class I postoperatively compared with 11 (65 percent) of 17 patients whose postoperative ejection fraction was 0.50 or less (p less than 0.05). No preoperative factor, including preoperative ejection fraction or cardiothoracic ratio, predicted the postoperative ejection fraction. A postoperative exercise ejection fraction was obtained in 29 patients, and an abnormal ejection fraction change with exercise (increase less than 0.05) was observed in 20 patients (69 percent). Patient age at the time of study correlated inversely with the change in ejection fraction from rest to exercise; no other variables were predictive. It is concluded that, in addition to age, only preoperative left ventricular function as measured by ejection fraction predicts survival in patients undergoing mitral valve replacement for isolated mitral regurgitation. Clinical recovery is good even though the majority of long-term survivors have a postoperative decrease in ejection fraction.

Early changes in left ventricular size and function after correction of left ventricular volume overload

The ability to predict early postoperative left ventricular size and function in patients with isolated aortic or mitral regurgitation was determined utilizing multigated blood pool imaging before and 2 to 4 weeks after valve replacement (aortic valve, 20 patients; mitral valve, 20 patients). Early postoperatively, ejection fraction decreased significantly (p <0.001) in both patient groups (from 0.55 ± 12 to 0.40 ± 0.14 [mean ± 1 standard deviation] in patients with aortic regurgitation and from 0.66 ± 0.09 to 0.48 ± 0.11 in patients with mitral regurgitation). The decrease in ejection fraction was associated with a large decrease in stroke volume with minimal or no change in end-systolic volume; it was unrelated to the preoperative ejection fraction. Early postoperative ejection fraction correlated best with preoperative end-systolic volume and was normal in 14 (67 percent) of 21 patients with a preoperative ejection fraction above 0.60; 4 (27 percent) of 15 patients with a preoperative ejection fraction of 0.50 to 0.60; and in 0 of 4 patients with a preoperative ejection fraction below 0.50 (p <0.05). In addition, a repeated scan in 16 patients late (1 to 2 years) after operation showed a further reduction in endsystolic volume in patients with aortic regurgitation with an increase in ejection fraction toward preoperative values. There was no significant change in patients with mitral regurgitation. End-diastolic volume decreased significantly (p <0.001) early postoperatively (from 162 ± 60 to 102 ± 41 ml/m2 in patients with aortic regurgitation and from 131 ± 40 to 78 ± 30 ml/m2 in patients with mitral regurgitation). This decrease was closely related to a decrease in stroke volume and was unrelated to preoperative ejection fraction. Early postoperative end-diastolic volume correlated best with the preoperative end-systolic volume. The major part of the reduction in end-diastolic volume occurred within 2 weeks of valve replacement. Removal of chronic left ventricular volume overload due to aortic or mitral regurgitation produces a decrease in ejection fraction and end-diastolic volume. The early reduction is in part a result of altered loading conditions and may not necessarily imply alterations in myocardial contractile function. The reduction in ejection fraction appears to persist in patients with mitral regurgitation.

Attenuation of the stress response to cardiopulmonary bypass by the addition of pulsatile flow.

The effect of pulsatile flow during cardiopulmonary bypass on the hormonal stress response was studied in 26 patients. Thirteen had routine bypass and 13 had pulsatile bypass with an average pulse pressure of 30 mm Hg. Plasma vasopressin levels were significantly elevated during bypass in both groups, but were lower with pulsation (66 ± 11 vs 36.3 pg/ml, p < 0.05). Epinephrine levels increased in both groups during bypass, but were higher after bypass (1179 ± 448 vs 713 ± 140 pg/ml, p < 0.05) and in the recovery room (1428 ± 428 vs 699 ± 155 pg/ml, p < 0.05) in the nonpulsatile group. The same response was noted in the norepinephrine levels (924 ± 225 vs 465 ± 90 pg/ml, p < 0.05; 1915 ± 491 vs 717 ± 112 pg/ml, p < 0.05). There were no significant changes in renin activity in either group, but the increase after cardiopulmonary bypass was greater in the nonpulsatile group (2.0 ± 0.7 vs 1.36 ± 0.4 ng/mI/hr, NS). These data suggest that pulsatile flow significantly attenuates the vasopressin and catecholamine stress response to cardiopulmonary bypass. This may explain the increased flow requirements and better tissue perfusion and organ function and the decreased incidence of postoperative hypertension after bypass using pulsatile flow.

Plasma Vasopressin Levels and Urinary Sodium Excretion during Cardiopulmonary Bypass with and without Pulsatile Flow

The use of pulsatile perfusion during bypass should create a more physiological milieu and thus attenuate the vasopressin stress response. To determine this, 20 patients scheduled for elective coronary artery bypass operation were studied in two groups. Group 1 had a standard nonpulsatile perfusion, and in Group 2 a pulsatile pump was used. Measurements were made before and after anesthesia, after surgical incision, and at 15 and 30 minutes during and after cardiopulmonary bypass. In both groups, vasopressin levels were significantly elevated after sternotomy (4.5 +/- 1.5 to 37 +/- 10 pg/ml in Group 1 and 3.1 +/- 1.2 to 33 +/- 9 pg/ml in Group 2, p less than 0.05) and during bypass (198 +/- 19 pg/ml in Group 1 and 113 +/- 16 pg/ml in Group 2) but were higher in Group 1 (p less than 0.05). With comparable perfusion pressures in both groups, Group 2 required higher flow (4.2 +/- 0.2 versus 3.5 +/- 0.3 L/min, p less than 0.05) and had lower resistance (1,351 +/- 182 versus 1,841 +/- 229 dynes sec cm-5, p less than 0.05) and higher urine Na+ (123 +/- 5 versus 101 +/- 8 mEq/L, p less than 0.05). These data demonstrate that pulsatile flow can significantly attentuate the vasopressin stress response to bypass. Since vasopressin, at these concentrations, is a potent vasoconstrictor and is capable of producing a Na+ diuresis, this may partially explain the higher flow requirements and the decrease in Na+ excretion.

Effect of ventricular pacing on left ventricular function assessed by radionuclide angiography

Radionuclide angiography was used to evaluate left ventricular contraction on and off ventricular pacing in 35 patients. Twenty patients had permanent rate-adjustable ventricular demand pacemakers whose rate could be programmed to below an underlying sinus rhythm. In these patients there was no difference in left ventricular ejection fraction on and off pacing whether or not heart failure was present (n = 7) or whether or not ventriculoatrial conduction (n = 10) developed during pacing. Eight of the 20 patients also underwent supine bicycle exercise, and rest and exercise ejection fraction values were not significantly different at a similar heart rate and workload when on and off pacing were compared. During pacing, there appeared to be abnormal motion in septal, apical, and inferior walls. In addition, dysynchrony developed, consisting of early right ventricular and anterobasal and posterobasal left ventricular motion with subsequent contraction of the apex. Conversion to atrioventricular pacing produced a clinical improvement in all seven patients with heart failure and reduced ejection fraction and also in one of the remaining 13 patients without heart failure. Fifteen other patients were studied early after cardiac surgery. Temporary ventricular epicardial pacing resulted in a significant increase in right and left atrial pressure and a significant reduction in stroke volume, end-diastolic volume, and end-systolic volume with no significant change in ejection fraction. Conversion from sinus rhythm to ventricular pacing produces a deterioration in cardiac performance and severe regional left ventricular wall motion abnormalities, but no significant change in ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Safe early revascularization for continuing ischemia after acute myocardial infarction.

SUMMARY Early revascularization following myocardial infarction (MI) is reported to have a high risk of extension of and hemorrhage into infarction with resulting high mortality and morbidity. To evaluate this issue, 80 post-MI patients (aged 32-74 years) with unstable angina pectoris resistant to maximal medical therapy were reviewed. All patients underwent early uncomplicated angiography and subsequent revascularization; 55 (69%) were less than 10 days post-MI, and 25 (31%) were 10-30 days post-MI. Intraaortic balloon pumping was required in 72% for relief of intractable angina or hemodynamic instability. Of the 80 patients, 19% had single vessel disease (VD), 31% double VD, and 50% triple VD. The mortality rate from coronary bypass surgery was 7/80 (8.8%), with four cardiac and three noncardiac deaths. Two patients suffered a perioperative MI (2.5%). At a mean follow-up period of 33 months, there had been only one late death and one recurrent nonfatal MI; 96% of the patients had no significant angina. In patients with continuing ischemia immediately after MI, myocardial revascularization can be safely performed without further injury to the myocardium, and with excellent long-term results.

Refractory ventricular tachycardia complicating recovery from acute myocardial infarction: Treatment with map-guided infarctectomy

Recurrent ventricular tachycardia (VT) and ventricular fibrillation (VF) complicating recovery from acute myocardial infarction (MI) present a formidable problem. When vigorous medical therapy with antiarrhythmic drugs, overdrive pacing, and the use of pharmacologic agents designed to reduce ischemia and improve left ventricular (LV) function fail to control ventricular arrhythmias, most of the patients die in the hospital or shortly following discharge.l A more radical mode of therapy in this very high-risk group of patients has used infarctectomy with or without myocardial revascularization.2-6 In the present study, the technique of guided endocardial excision,7p* in addition to infarct resection, was used as an urgent intervention in 10 clinically unstable patients, whose recovery from acute MI was complicated by poor LV function and recurrent VT refractory to medical therapy. This report describes our clinical, electrophysiologic, and angiographic findings and the postoperative followup in this group of 10 patients.

Hyperlipoproteinemia as a Significant Risk Factor for Pulmonary Embolism in Patients Undergoing Coronary Artery Bypass Grafting

A five-year (1975 through 1979) retrospective analysis of all cardiac surgical patients who sustained a postoperative pulmonary embolism was undertaken, and lipoprotein profiles of these patients were evaluated. Twenty-six patients (20 men and 6 women) were identified who had definite clinical, laboratory, and radiological evidence of pulmonary embolism in the postoperative period. Twenty had undergone coronary artery bypass grafting, and the remaining 6 had undergone other cardiac surgical procedures. Of the 20 patients who had coronary bypass, 19 (95%) were found to have hyperlipoproteinemia (14 patients with type II and 5 with type IV). There were 4 hospital deaths (15%), all related to pulmonary embolism. The 4 patients had undergone coronary bypass procedures, and all had type II hyperlipoproteinemia. Since patients with hyperlipoproteinemia made up less than 10% of the coronary bypass population, the incidence of pulmonary embolism in this group is highly significant (p less than 0.001). Experimental evidence has shown that patients with hyperlipoproteinemia, especially type II, have increased platelet adhesiveness and aggregation, and coagulation abnormalities consistent with a hypercoagulable state. This retrospective study clinically confirms that finding and suggests that early postoperative anticoagulation therapy may be indicated in patients with hyperlipoproteinemia, particularly type II, to reduce thromboembolic complications.

Temperature Gradients and Rewarming Time During Hypothermic Cardiopulmonary Bypass With and Without Pulsatile Flow

Pulsatile perfusion during cardiopulmonary bypass (CPB) has been reported to have a number of beneficial effects, including attenuation of hormonal stress responses and improved organ blood flow and function. To determine the effect of pulsatile perfusion on temperature gradients and the time required for cooling and rewarming during CPB, we studied 21 patients scheduled for elective coronary artery operations. The patients were divided into two comparable groups: Group 1 (N = 11) had standard nonpulsatile perfusion, while in Group 2 (N = 10), a pulsatile pump was used. Rectal and esophageal temperatures were monitored, as were deltoid muscle temperatures and upper arm and finger skin temperatures in the same extremity. Ambient temperature, bypass flow and pressure, and bypass time were similar in both groups. Time required to cool to the lowest esophageal temperature was virtually identical for both groups (Group 1, 17 +/- 3 min; Group 2, 17.6 +/- 5 min), as was rewarming time (Group 1, 26.8 +/- 11 min; Group 2, 27.2 +/- 6 min). There were no significant differences in temperature measurements between groups except briefly during rewarming when finger skin temperature rose more rapidly in Group 1 (p less than 0.05). Temperature changes following CPB were the same for both groups, with rectal and esophageal temperatures showing an inverse relationships. These data demonstrate that pulsatile flow does not substantially alter rewarming time or temperature gradients during hypothermic CPB.

The effect of adding mannitol or albumin to a crystalloid cardioplegic solution: a prospective, randomized clinical study

To determine if the myocardial protection afforded by a cold crystalloid potassium cardioplegic solution could be improved by the addition of either mannitol or albumin, a prospective clinical study was undertaken in which 58 patients undergoing elective aortocoronary bypass were randomized to one of three groups. Each group featured a different cardioplegic solution. The solutions were a standard potassium crystalloid solution, a solution containing mannitol sufficient to raise the osmolality by 20 to 30 mOsm, and a solution containing 5% albumin. Preoperative, intraoperative, and postoperative evaluation included serial measurements of ejection fraction, myocardial-specific isoenzyme, and hemodynamic indexes of performance. Electrocardiographic evaluation for perioperative myocardial infarction and the need for postoperative inotropic and mechanical support were also included. No differences were found among the groups. Therefore, although the use of mannitol or albumin has been shown to be beneficial in an experimental setting, superiority of either additive could not be demonstrated clinically.