A. Michael Borkon

Stroke following coronary artery bypass grafting: A ten-year study

To identify possible risk factors for the occurrence of stroke during coronary artery bypass grafting (CABG), the cases of 3,279 consecutive patients having isolated CABG from 1974 to 1983 were reviewed. During this period, the risk of death fell from 3.9% to 2.6%. The stroke rate, however, fell initially but then rose from 0.57% in 1979 to 2.4% in 1983. Adjustment of these data for age clearly demonstrated that the risk of stroke has increased largely because of an increase in the mean age of patients undergoing CABG procedures. A case-control study involving all 56 stroke victims and 112 control patients was used to identify those risk factors significantly associated with the development of stroke in univariate analysis: increased age (63 versus 57 years in stroke patients and controls, respectively; p less than 0.0001); preexisting cerebrovascular disease (20% versus 8%; p less than 0.03); severe atherosclerosis of the ascending aorta (14% versus 3%; p less than 0.005); protracted cardiopulmonary bypass time (122 minutes versus 105 minutes; p less than 0.005); and severe perioperative hypotension (23% versus 4%; p less than 0.0001). Other variables not found to correlate with postoperative stroke included previous myocardial infarction, hypertension, diabetes mellitus, lower extremity vascular disease, preoperative left ventricular function, and intraoperative perfusion techniques. Elderly patients who have preexisting cerebrovascular disease or severe atherosclerosis of the ascending aorta or who require extensive revascularization procedures have a significantly increased risk of postoperative stroke.

Identification of patients at high risk for complications of intraaortic balloon counterpulsation: A multivariate risk factor analysis

Risk factors for vascular complications of intraaortic balloon (IAB) counterpulsation were evaluated in 206 consecutive patients. The approach was percutaneous in 105 patients and surgical cutdown in 101. Vascular complications occurred in 42 patients, and of these 21 required surgery. Multivariate analysis demonstrated the following major risk factors for vascular complications: preexisting peripheral vascular disease (PVD) defined as a history of claudication, femoral bruit or absent pedal pulse (p less than 0.01); and the use of the percutaneous approach (p = 0.02). Evidence of PVD was particularly predictive of major vascular complications requiring surgery (p less than 0.01). In patients with evidence of previous PVD, the risk for a major vascular complication was 31% with the percutaneous, and 16% with the surgical cutdown approach. Without PVD, the risk for a major vascular complication was 4 times higher in women (15%) than in men (3.5%), but in the presence of PVD gender had no significant effect (p = 0.03). Age, duration of IAB counterpulsation and indication for insertion were not significant risk factors. It is concluded that (1) without previous PVD, women are at greater risk than men for major vascular complications (due to smaller arterial size); and (2) evidence of previous PVD identifies patients at high risk for major vascular complications with IAB counterpulsation, particularly by way of the percutaneous approach.

Value of intraoperative left ventricular microbubbles detected by transesophageal two-dimensional echocardiography in predicting neurologic outcome after cardiac operations

To determine whether the presence or absence of left ventricular (LV) intracavitary microbubbles during cardiac surgery predicts neurologic sequelae, 82 patients undergoing cardiac surgery were studied using transesophageal 2-dimensional (2-D) echocardiography. Cross-sectional images were recorded just before and immediately after cardiopulmonary bypass and stop frames were reviewed for the presence of microbubbles, rated as: 0 = absent, 1 = fewer than 5/frame, 2 = 10 to 25/frame, 3 = too numerous to count. Microbubbles were detected after cardiopulmonary bypass in 34 patients (41%) and found more often in valvular or other intracardiac manipulations than in coronary revascularization, 30 of 40 vs 4 of 42, respectively (p less than 0.001). When grade 2 or 3 microbubbles were identified (22 of 34 patients), mechanical attempts to eradicate them were not successful. Postoperative follow-up in all patients revealed no new focal neurologic deficits. Prolonged encephalopathy (confusional state more than 72 hours) occurred in 4 of 48 patients with no detectable microbubbles and in 3 of 34 patients with microbubbles (difference not significant). Thus, intracavitary left ventricular microbubbles are often detected during cardiac operations, particularly during valve replacement, but are not predictive of postoperative neurologic complications. This is true even if microbubbles are densely concentrated; attempts to eradicate microbubbles are unsuccessful and may be unnecessary.

Aortic Valve Selection in the Elderly Patient

To determine the influence of valve selection on valve-related morbidity and mortality and patient survival, comparative long-term performance characteristics of mechanical (N = 68) and bioprosthetic (N = 73) heart valves were analyzed for 141 patients more than 70 years old who underwent isolated aortic valve replacement between 1970 and 1985. Cumulative patient follow-up was 491 patient-years (average, 4.3 years per patient). Hospital mortality was 18% and 19% for patients with mechanical valves and bioprosthetic valves, respectively. Survival at 5 years was 61 +/- 7% (+/- the standard error) and 67 +/- 10% for recipients of mechanical valves and bioprosthetic valves, respectively. Male sex (p = 0.014) and urgency of operation (p = 0.006) were independent risk factors for hospital mortality. Atrial fibrillation increased valve-related mortality (p = 0.01). No patient required reoperation or experienced structural valve failure. While anticoagulant-related hemorrhage was increased in recipients of mechanical valves (9.2 +/- 2.1%/patient-year) compared with recipients of bioprosthetic valves (2.3 +/- 1.1%/patient-year), it did not result in a death or lead to permanent disability. There was no difference in freedom from any valve-related complication at 5 years. However, when all morbid events are considered, recipients of bioprosthetic valves experienced fewer valve-related complications than patients receiving mechanical valves (10.7 +/- 2.3%/patient-year versus 17.6 +/- 2.5%/patient-year, respectively; p less than 0.05). The reduced incidence of anticoagulant-related hemorrhage and the infrequent need for warfarin sodium anticoagulation favor selection of a bioprosthetic heart valve in patients older than 70 years.

Diagnosis and Management of Postoperative Pericardial Effusions and Late Cardiac Tamponade Following Open-Heart Surgery

The clinical and laboratory findings of 28 patients identified as having late pericardial effusions were examined. Eleven of these patients were asymptomatic; 9 patients had moderate symptoms including fatigue, malaise, weight gain, and dyspnea on exertion, and 8 patients with similar symptoms had evidence of cardiac tamponade. Ten patients underwent right heart catheterization in the intensive care unit; normal hemodynamics were confirmed in 4 and cardiac tamponade in 6 patients. Pericardiocentesis was effective in decompressing cardiac tamponade in 7 of 8 patients. One patient required operative subxiphoid drainage after unsuccessful pericardiocentesis. In addition, 5 patients with moderate clinical symptoms and pericardial effusions, who did not have cardiac tamponade, underwent pericardiocentesis because of a need for chronic anticoagulant therapy. The remaining patients were managed successfully by observation, discontinuation of warfarin when possible, fluid restriction, and diuretic therapy. All but 1 patient was symptomatically improved. A diagnostic and therapeutic schema is presented as an aid to early recognition of this troublesome and potentially lethal complication.

Bio-Medicus ventricular assist device for salvage of cardiac surgical patients

Over a 5-year period, 41 (1%) of 4,193 patients undergoing cardiac operations underwent intraoperative or early postoperative insertion of a Bio-Medicus ventricular assist device when it became apparent that the patient could not otherwise survive. Fourteen patients were in cardiogenic shock and 7 were in cardiac arrest at the time of initiation of their primary cardiac surgical procedure, and in no instance was the device planned as a bridge to cardiac transplantation. Bleeding, sepsis, and thromboembolism were frequent postoperative complications. Central nervous system deficits were observed in 16 patients during their postoperative course. Eight patients (19.5%) were long-term survivors. Of the preoperative risk factors evaluated only age was significantly associated with survival, with 7 (33%) of the 21 younger (39 to 63 years) patients surviving. Blood product usage and hospital cost were analyzed in an attempt to assess cost/effectiveness of use of this device for attempted salvage of such desperately ill patients.

Assessment of myocardial blood flow by real-time infrared imaging☆

In order to evaluate the applicability of infrared imaging for the assessment of myocardial perfusion, 10 open-chested dogs were studied by a real-time infrared imaging system. The left anterior descending coronary artery was occluded for 90 min followed by 210 min of reperfusion. During the experiment, myocardial surface temperature was mapped by an infrared imaging system with a thermal resolution power of 0.1 degree C and correlated with regional myocardial blood flow measured using radiolabeled microspheres. Following the experiment, acute myocardial injury was evaluated using triphenyltetrazolium chloride staining. After 90 min of ischemia, there was a significant correlation between myocardial blood flow and myocardial surface temperature (R = 0.694, P less than 0.001). After reperfusion, temperature did not correlate with blood flow, but there was a significant correlation between temperature and ischemic myocardial injury (R = 0.551, P less than 0.05). Temperature changes during acute regional ischemia and reperfusion may be regulated by the changes in myocardial blood flow and myocardial metabolism. Temperature analysis using real-time infrared imaging may be a useful means for the evaluation of myocardial blood flow and myocardial injury during ischemia and reperfusion.

Present Expectations in Cardiac Transplantation

The clinical introduction of cyclosporine has resulted in increased enthusiasm for cardiac transplantation. Since July, 1983, 61 patients (50 male and 11 female) have undergone orthotopic cardiac transplantation for cardiomyopathy (48 patients), ischemic heart disease (11), or congenital heart disease (2). Mean age was 39 years (range, 1.5 to 57 years). Median hospital stay was 26 days (range, 4 to 60 days). Maintenance immunosuppression consisted primarily of prednisone and cyclosporine; it was modified in 9 patients because of a pre-existing clinical condition. The incidence of rejection was 0.44 episode/patient-month within 3 months of cardiac transplantation and 0.10 episode/patient-month subsequently. The incidence of infection was 0.05 episode/patient-month. Major side effects of cyclosporine included renal dysfunction (63%) and hypertension (61%). No recipient required dialysis for renal dysfunction. Ten patients died (rejection, 4; infection, 3; carcinoma, 1; lymphoma, 1; and pulmonary hemorrhage, 1); actuarial survival at 1 and 2 years was 84 +/- 6% and 76 +/- 8%, respectively. Patient follow-up (cumulative, 719 patient-months) revealed that 96% of recipients were rehabilitated and 50% had returned to work. With increasing understanding of cyclosporine immunosuppression, recipients can continue to look forward to an extended life with nearly complete rehabilitation.

The superior QRS axis in ostium primum ASD: A proposed mechanism

The influence of abnormal hemodynamics, ventricular hypertrophy, and right bundle branch block on the AQRS was studied pre- and post-operatively in 29 patients with OPSD. The AQRS markedly diminishes with the surgical correction of abnormal hemodynamics and the subsequent resolution of RVH or BVH. With the persistence of ventricular hypertrophy postoperatively or the surgical induction of RBBB, the AQRS either remains unchanged or, in the latter instance, becomes more superior and rightward. The dependence of the superior AQRS on these factors suggests that a left anterior hemiblock is not responsible for this AQRS. In OPSD early activation of the posterobasal region of the left ventricle through an abnormally short posterior fascicle results in a minimal superior AQRS which is then exaggerated in the presence of abnormal hemodynamics, ventricular hypertrophy, or RBBB. Thus, the superior AQRS in OPSD with associated RBBB does not represent a true bifascicular block and has a different natural history and clinical significance.

Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement

Background— Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. Methods and Results— We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P<0.001) and an increase in valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm2, P<0.001). No procedural complications were reported. Conclusions— BVF can be performed safely in small surgical valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area.