David M. Conkle

Operative treatment in hypertrophic subaortic stenosis. Techniques, and the results of pre and postoperative assessments in 83 patients.

The results of operative treatment in 83 patients with idiopathic hypertrophic subaortic stenosis (IHSS) are described. Most patients with the disease are asymptomatic, or derive satisfactory symptomatic improvement from nonoperative therapy: administration of propranolol, exercise limitation, control of arrhythmia, etc. Operation is required, however, in 10-15% of patients, those who remain severely symptomatic after nonoperative treatment or who become refractory to it. Operation relieves symptoms in IHSS by relieving obstruction to left ventricular outflow, and for a patient to be considered an operative candidate severe obstruction must be documented at left heart catheterization either under resting conditions or after provocative interventions. All 83 patients were severely incapacitated — 58 in Class III and 24 in Class IV. Seventy had obstruction at rest (average gradient 96 mm Hg), and 13 had only provocable obstruction. At operation the hypertrophic interventricular septum was exposed via an aortotomy, and a vertical bar of muscle was resected between parallel myotomy incisions. There were six operative deaths (7%); no patient has died since 1970. Seven patients have died late after operation, five of them from causes unrelated to their heart disease or the operation. All surviving patients describe symptomatic improvement. Fifty-two patients with obstruction at rest preoperatively (average gradient 95 mm Hg) have been studied postoperatively: no resting gradient was evident in 47, while in the remaining five the gradient was less than 25 mm Hg. Recurrence of obstruction has never been observed at late catheterization (21 pts) or late echocardiographic examination (37 pts). Obstruction could not be provoked postoperatively in ten of the 11 patients who had large gradients only with the Valsalva maneuver or isoproterenol administration preoperatively. Obstructed and provocable obstructed patients had similar symptomatic improvement after operation. A variety of rhythm and conduction abnormalities were observed both pre and postoperatively, and these are described in detail. The results of operation in these 83 patients with IHSS demonstrate that gratifying symptomatic and hemodynamic improvement uniformly follows left ventriculomyotomy and myectomy. Relief of obstruction and amelioration of symptoms have proved to be long-lasting during postoperative observation periods extending to 14 years. Continued application of the operative procedure in properly selected patients appears to be indicated.

Evaluation of computed tomography in the detection of pulmonary metastases. A prospective study

Conventional linear x‐ray tomography is often used to search for pulmonary metastases but tends to underestimate extent of disease when compared with operative findings. In a prospective study, operative findings were correlated with computed axial tomography and conventional linear tomography performed on 25 patients with a history of extrathoracic malignancy and pulmonary nodules. Computed tomography detected 69 nodules of which 31 proved to be metastases. Conventional linear tomography detected 38 nodules of which 25 were metastases. Of the 54 resected nodules measuring >3 mm, computed tomography detected 42; whereas conventional tomography detected 32. Only six of the 31 additional nodules (20%) detected by computed tomography and not by conventional tomography proved to be metastases. These results suggest that computed tomography is more sensitive than conventional tomography in detecting small pulmonary nodules; however, there is diminished specificity in identifying metastatic nodules. Cancer 43:913–916, 1979.

Effects of Coronary-Artery Bypass on Global and Regional Left Ventricular Function during Exercise

To determine the effect of coronary revascularization on exercise-induced abnormalities of left ventricular-ejection fraction and regional contraction, we obtained electrocardiograph-gated 99mTc radionuclide cineangiograms before and after operation in 23 consecutive patients. At rest, their average ejection fraction remained unchanged: 51 +/- 3 versus 54 +/- 4 per cent (+/- S.E.M.). However, 17 of the patients showed improvement of ejection fraction during postoperative exercise (increase of 51 per cent). The remaining six patients had no change or a decreased ejection fraction during exercise. All patients with improved ejection fractions during exercise were symptomatically improved. No improvement of regional function occurred at rest, but improvement did occur in regions of exercise-induced dysfunction. Although coronary revascularization has little effect on left ventricular function at rest, the ejection fraction during exercise and exercise-induced wall-motion abnormalities improve in most patients who experience symptomatic improvement.

Lesions Observed in Arterial Autogenous Vein Grafts Light and Electron Microscopic Evaluation

Autogenous vein grafts used for canine femoral and aortocoronary arterial bypasses were evaluated from 2 to 365 days postoperatively. Femoral grafts showed focal endothelial disruption, mural fibrin deposition, and medial edema with inflammatory infiltrates during the first week; loss of medial smooth muscle cells and focal subendothelial lesions with intact endothelium by 2 weeks; and diffuse subendothelial lesions by 12 weeks, Coronary grafts studied at 6, 9, and 12 months had medial fibrosis and extensive intimal proliferation causing up to 90% luminal narrowing. Extension of the intimal process into the coronary artery distal to the bypass graft also compromised the arterial lumen. Coronary grafts obtained from humans dying 17 and 57 days after graft insertion revealed a similar subendothelial proliferation.Electron microscopy showed that the subendothelial lesions were composed of mature smooth muscle cells and collagen primarily oriented parallel to the axis of blood flow. Recurrent endothelial cell damage, followed by mural fibrin deposition and organization, appears to be the cause of the subendothelial proliferative lesions.

Effects of tachycardia on the function of the Starr-Edwards mitral ball valve prosthesis

Abstract Patients with a Starr-Edwards mitral ball valve prosthesis tolerate tachycardias poorly. Two patients with this type of mitral valve prosthesis are described who tolerated supraventricular tachycardia with a ventricular response of 220 beats/min. At rapid heart rates, the diastolic filling period is reduced, left atrial pressure is increased and, although continued function of the prosthesis is possible, prompt treatment of arrhythmias accompanied by rapid ventricular rates is indicated.