Jimmy F. Howell

Relation of tissue Doppler derived myocardial velocities to myocardial structure and beta-adrenergic receptor density in humans.

OBJECTIVES We sought to evaluate the relation of segmental tissue Doppler (TD) velocities to both the regional amount of interstitial fibrosis and the myocyte beta-adrenergic receptor density in humans. BACKGROUND The systolic myocardial velocity (Sm) and early diastolic myocardial velocity (Em) acquired by TD are promising new indexes of left ventricular function. However, their structural and functional correlates in humans are still unknown. METHODS Ten patients with coronary artery disease underwent echocardiographic examination including TD imaging, along with transmural endomyocardial biopsy at the time of coronary bypass surgery (two biopsies per patient for a total of 20 specimens). The specimens were analyzed for percent interstitial fibrosis and beta-adrenergic receptor density. RESULTS Normal segments (n = 8) had a higher beta-adrenoceptor density (2,280 +/- 738 vs. 1,373 +/- 460, p = 0.03) and a lower amount of interstitial fibrosis (13 +/- 3.3% vs. 28 +/- 11.5%, p = 0.002) than dysfunctional segments (n = 12). Myocardial systolic velocity and Em were also significantly higher (9.5 +/- 2.7 vs. 5.9 +/- 1.8 cm/s, p = 0.025 and 11.3 +/- 2.8 vs. 6.4 +/- 2.1 cm/s, p = 0.002, respectively) in normal segments. A significant relationship was present between Em and the beta-adrenergic receptor density (r = 0.78, p < 0.001) and percent interstitial fibrosis (r = -0.7, p = 0.0026), which together accounted for 81% of the variance observed in Em. Likewise, a significant relationship was present between Sm and the beta-adrenergic receptor density (r = 0.68, p < 0.001) and the percent interstitial fibrosis (r = -0.66, p = 0.004) and together accounted for 62% of the variance observed in Sm. CONCLUSIONS Systolic myocardial velocity and Em are strongly dependent on both the number of myocytes and the myocardial beta-adrenergic receptor density.

Operative Risk in Patients with Previous Coronary Artery Bypass

Noncoronary operations were performed in 358 patients who had undergone a previous coronary artery bypass grafting, with a mortality of 1.1%. In 70 patients (20%), the staged operation was planned and subsequent operation performed 6 to 12 weeks after bypass with no cardiac complications and 1 death. In the others, operation was performed 10 days to 89 months after bypass for either urgent reasons or new lesions. Three deaths and significant numbers of medical cardiac complications occurred in those patients subjected to operation within 30 days. The subsequent operation was vascular in 232 patients, with 3 deaths (1.3%); thoracic in 43, with no deaths; and general surgical in 113, with 1 death (0.9%). Follow-up study showed 307 patients (87%) still alive after 30 days to seven years. Late death was due to myocardial infarction in only 12 patients (3%). This study suggests that the risk of operation is as good in patients who have had successful coronary artery bypass as in those without coronary artery disease, and that the risk of subsequent myocardial infarction is small.

Preliminary Observations of the Effects on Breast Adenocarcinoma of Plasma Perfused over Immobilized Protein A

PROTEIN A, a constituent of the cell wall of Staphylococcus aureus Cowans 1 (SpA), reacts with the Fc region of immunoglobulins from many mammalian species and combines with immune complexes in ser...

Assessment of Myocardial Viability With 99mTc-Sestamibi Tomography Before Coronary Bypass Graft Surgery Correlation With Histopathology and Postoperative Improvement in Cardiac Function

BACKGROUND Assessment of myocardial viability by 99mTc-sestamibi remains controversial. Accordingly, we investigated the use of sestamibi as a marker of myocardial viability, defined by histopathology, and for predicting improvement of myocardial function after coronary artery bypass graft surgery (CABG). METHODS AND RESULTS 99mTc-sestamibi perfusion tomography and radionuclide angiography were performed within 2 days before CABG in 21 patients with > or = 75% stenosis of the left anterior descending coronary artery and resting anterior wall dyssynergy. During CABG, transmural myocardial biopsies were obtained from the dyssynergic anterior wall and from normal myocardial segments to determine the extent of viable myocardium by histopathology. Improvement of regional left ventricular function was evaluated by radionuclide angiography at 6 to 8 weeks after CABG. There was a good correlation (r=.85, P<.001) between the quantified sestamibi activity and the extent of viable myocardium determined morphometrically. Among 21 biopsied dyssynergic myocardial segments, 11 improved their function after CABG and 10 failed to improve. Biopsied segments with improved postoperative function had significantly higher sestamibi activity (81+/-5% versus 49+/-16%, P<.0001) and significantly lower extent of interstitial fibrosis (7+/-4% versus 31+/-21%, P=.0002) than segments that failed to improve. A 55% threshold of 99mTc-sestamibi activity had positive and negative predictive values of 79% and 100%, respectively, for recovery of function after CABG in the biopsied segments. CONCLUSIONS Myocardial 99mTc-sestamibi activity correlates well with the extent of viable myocardium and predicts improvement in regional function after CABG. This lends support to the use of sestamibi as a myocardial viability agent.

Relation of the Contractile Reserve of Hibernating Myocardium to Myocardial Structure in Humans

BACKGROUND Although dobutamine echocardiography (DE) is widely used to assess myocardial viability in humans, little is known about the relation between contractile reserve and myocardial structure. METHODS AND RESULTS We evaluated 20 patients with coronary disease (64+/-13 years old, ejection fraction 28+/-7.5%) with DE (up to 40 micrograms . kg(-1). min(-1)), rest-redistribution (201)Tl single photon emission CT, and quantitative angiography before bypass surgery. During surgery, patients underwent transmural myocardial biopsies (n=37) guided by transesophageal echocardiography to determine the extent of interstitial fibrosis and intracellular and interstitial proteins by histopathology and immunohistochemistry. Among the 37 segments biopsied, 16 recovered function as assessed 2 to 3 months later. Segments with postoperative functional recovery had more wall thickening at low-dose DE (28% versus 3%, P<0.001), higher thallium uptake (69% versus 48%, P=0.03), and less interstitial fibrosis (2% versus 28%, P<0.001). Quantitative angiographic parameters did not predict recovery of function. Segments with DE viability (contractile reserve and/or ischemia) had less fibrosis (2.7% versus 28%, P<0.001), less vimentin and fibronectin (both P<0.01), more glycogen (P=0.016), and higher thallium uptake (64% versus 35.5%, P<0.05) than those without viability. Viable segments by both DE and thallium had less fibrosis (1%) than those viable by 1 of the 2 techniques (9%) or not viable by both (28%, P=0.005). Thickening at low-dose DE correlated well with the extent of interstitial fibrosis (r=-0.83, P<0.01). CONCLUSIONS Contractile reserve during DE correlates inversely with the extent of interstitial fibrosis and the amount of fibronectin and vimentin and directly with rest-redistribution thallium uptake.

Results of coronary bypass more than 5 years after operation in 434 patients. Clinical, treadmill exercise and angiographic correlations.

Abstract The long-term fate of 434 consecutive patients operated on between 1968 and 1971 was assessed. All patients were followed up for more than 60 months after operation (mean 70.7 months). Of the initial 434 patients, 98 died 0 to 74 (mean 31.1) months postoperatively. Of the 336 survivors, 152 reentered the hospital and underwent standardized clinical assessment. Angina was lessened in 93.4 percent (255 of 273) and absent in 51.3 percent (140 of 273) of these patients. Of patients under 65 years of age, 79.2 percent (152 of 192) were still working. Treadmill exercise tests performed in 107 patients showed an ischemic response in 44.9 percent (48 of 107) and an indeterminate response in 9.3 percent (10 of 107). The duration of the exercise, maximal pulse rate and double product all correlated well with the completeness of revascularization. In 176 patients with 256 grafts evaluated angiographically, the patency rate was 86.3 percent (221 of 256), and 94.3 percent of patients (166 of 176) had at least one patent graft. The average crude annual attrition rate after the first year was 2.3 percent per year, which approximates that of the general U.S. population after correction for age and sex. In the next 677 consecutive patients the survival rate after 5 years was 91.4 percent (including 4.7 percent operative mortality rate) compared with the survival rate of a similar normal population of 92.7 percent. The operative mortality rate of 7.1 percent in this early experience has been reduced to less than 2 percent in current experience. These results suggest that the coronary bypass procedure provides sustained symptomatic relief and may prolong life.

Follow-up results of distal coronary artery bypass for ischemic heart disease

Abstract Statistically significant late results of coronary artery bypass procedures will be unavailable for 5 to 10 years. This report summarizes a critical analysis of the present status of 480 patients followed up for 1 to 30 months after coronary artery bypass. Thirty-day hospital mortality was 6.2 percent and appears to be declining. Arteriographic studies have shown only 1 of 220 patients without at least 1 functioning graft. Graft occlusions appear to be early and technically oriented and ranged from 11 to 14 percent. Significant symptomatic improvement as determined by cardiologists was observed in 92 percent of patients. According to functional classification there was a striking shift from preoperative New York Heart Association classes II, III, and IV, to class I as a result of improved myocardial blood flow. No degenerative changes in autogenous vein bypass grafts have been observed.

Altered Adrenergic Receptor Density in Myocardial Hibernation in Humans A Possible Mechanism of Depressed Myocardial Function

Background—Alterations in adrenergic receptor densities can potentially contribute to myocardial dysfunction. Their relevance to myocardial hibernation in humans is unknown. Methods and Results—Accordingly, 22 transmural myocardial biopsies were obtained in 11 patients with ischemic ventricular dysfunction during bypass surgery, guided by transesophageal echocardiography. Patients underwent dobutamine echocardiography (DE) and rest scintigraphic studies before revascularization and DE at 3 to 4 months. &agr;- and &bgr;-receptor density (ARD and BRD) and extent of fibrosis were quantified from the myocardial biopsies. Of the 22 segments, 16 had abnormal rest function and 6 were normal. Severely hypokinetic or akinetic segments showed a 2.4-fold increase in ARD with a concomitant 50% decrease in BRD compared with normal segments. An increase in ARD, a decrease in BRD to a lesser extent, and thus an increase in ARD/BRD ratio were seen in dysfunctional segments with contractile reserve compared with normal segments and were most pronounced in those without contractile reserve (P <0.001). Similar findings were observed if recovery of function or scintigraphic uptake was analyzed as a marker for viability. No significant relation between either ARD or BRD and percent myocardial fibrosis was noted (r =0.37 and −0.39, respectively). Conclusions—Thus, graded and reciprocal changes in &agr;- and &bgr;-adrenergic receptor densities occur in viable, hibernating myocardium and may account in part for the observed depression in resting myocardial function and preserved contractile reserve in this entity.

Perforation of the pulmonary artery with Swan-Ganz catheters: diagnosis and surgical management.

Swan-Ganz catheters have become a very valuable and frequently used method of monitoring hemodynamics in sick patients. Although the incidence of complications is very low, more reports are beginning to appear. One of the more serious complications is the rupture of the pulmonary artery. This report concerns three patients who had a rupture of the pulmonary artery who survived, including one of almost fatal ex-anguination. A literature review of all cases of pulmonary artery rupture is presented. Fifty-three per cent (8/15) were fatal. Emphasis is placed on the prevention of this by using the guidelines. Discussion also covers possible contributing causes and treatment. A high index of suspicion is necessary whenever a patient with the catheter has hemoptysis or unexplained cardiac or respiratory changes.

Current Concepts in Coronary Artery Surgery: A Critical Analysis of 1,287 Patients

Abstract The clinical experience gained by performing aorta-to-coronary artery bypass grafts on 1,287 patients over the past four years is analyzed. Multiple procedures such as valve replacement and left ventricular aneurysmectomy were performed in 65 of these patients. In the remaining 1,222 patients, modifications in technique are demonstrated by comparing the recent group of 759 patients operated upon in 1971 to 463 patients operated upon previously. Both groups were similar with regard to the severity of disease. The recent group of 759 patients had more multiple graft procedures and a greater incidence of left circumflex coronary artery bypass. The mortality in that group was decreased to 4.5%. In the entire group the mortality rate was 6.4%, including operative and late mortality. Postoperative complications decreased with regard to ventricular arrhythmias and postoperative myocardial infarctions. Emergency coronary artery bypass was done in 20 of the patients over the past year, with a mortality of 35%. Postoperative assessment revealed marked to moderate improvement in all but 13% of the patients. Late results in patients with congestive heart failure and angina or with intractable Functional Class IV angina are compared with results in the remainder of the patients. A standard surgical approach for the treatment of coronary artery disease has resulted from review of these data.