A standardized examination in the interpretation of electrocardiograms.

A standardized objective examination was developed by the Cardiovascular Subspecialty Board of the American Board of Internal Medicine to assess competence in the interpretation of electrocardiograms (ECGs). The questions consisted of 12 lead ECGs with lead II and V1 rhythm strips, accompanied by brief clinical statements. Examinees chose their answers from a comprehensive list of 129 choices; the list was the same for each question. The score from the ECG examination was combined with scores from the other sections of the examination to derive a single score for the Cardiovascular Board examination using a norm-referenced method for determining the passing score. An additional trial was conducted to study the feasibility of testing for a minimal level of competence; the trial used a subset of "core" ECGs and a criterion-referenced scoring method based on a consensus of members of the Cardiovascular Board on the level of performance that should be expected of certified cardiologists. Fifty examinees (2.7%) failed the core ECG examination. If examinees had been required to pass both the core ECG examination and the remainder of the examination, 164 examinees (9%) would have changed their pass-fail status on the overall examination. The examination appeared to be a valid test for a minimal level of skill in this area of cardiology. The minimal level of competence was met by a large majority but not all of the examinees.

Life-threatening arrhythmias in the mitral valve prolapse syndrome.

This study describes seven patients with the mitral valve prolapse or click-murmur syndrome who have survived one or more episodes of life-threatening ventricular arrhythmias. These arrhythmias include cardiac arrest due to ventricular fibrillation, recurrent ventricular tachycardia causing syncope or sustained ventricular tachycardia requiring electroversion. These patients were seen over a two-year period in a single medical center. Five of the seven had repolarization abnormalities in the resting electrocardiogram. Premature ventricular contractions were present in the routine resting electrocardiograms of six of the seven patients and were frequent during treadmill testing and ambulatory electrocardiographic monitoring in all six tested. There were electrolyte abnormalities or changes in medications known to affect myocardial repolarization during the week before the episode in three of the four patients with cardiac arrest. The diagnosis of mitral valve prolapse click-murmur syndrome was made prior to the episode of life-threatening arrhythmia in only two of the seven patients. Varying forms of antiarrhythmic therapy were given to these patients during follow-up periods of five to 26 months. Although the incidence of fatal arrhythmias in the mitral prolapse syndrome is probably small, we suggest that such arrhythmias may not be extremely rare, particularly among those patients who have repolarization abnormalities in the resting electrocardiogram and frequent premature beats. Patients with unexplained ventricular arrhythmias should be screened for mitral valve prolapse.

Long-term follow-up of aortic valve replacement with the fresh aortic homograft.

The long-term results of aortic valve replacement with the fresh aortic homograft, performed in 114 patients at Stanford University Medical Center from 1967 to 1971, were evaluated. There were 10 operative deaths (8.8 per cent), only 3 (5 per cent) in the period from 1968 to 1971. There were 6 late deaths in the first year (5.8 per cent) and 8 in later years (1.5 per cent per year); 12 late deaths were due to cardiac causes, 6 of them to valve dysfunction. The homograft was replaced later with a prosthetic valve or heterograft in 22 patients (3.2 per cent per year): for regurgitation in 20 and for calcific stenosis in only one. Infective endocarditis occurred in 5 cases, accounting for one operative death, 2 late deaths, and 2 reoperations with survival. Systemic thromboembolism occurred in 6 patients, 3 with mitral valve disease, one with atrial fibrillation, and one with infective endocarditis; none was a proved instance of embolism from bland thrombus on the aortic homograft valve. Of 53 patients followed for 5 years or more with the homograft intact, 47 have minimal or no disability, despite aortic diastolic murmurs in many. We conclude that long-term results are good in the majority of patients, with aortic regurgitation requiring reoperation being the leading complication. These results may serve as a basis for comparison of more recently introduced methods of aortic valve replacement.

Noninvasive diagnosis of complications of the mitral bioprosthesis.

The echophonocardiographic diagnoses of valvular and paravalvular insufficiency, calcific stenosis, and thrombolic occlusion of the stent-mounted aortic homograft or heterograft in the mitral position are described. Paravalvular and valvular insufficiency were associated with apical systolic murmurs which decreased in intensity after amyl nitrite inhalation and with echocardiograms which showed initial diastolic slopes of the stents in excess of the normal range (1.9 to 3.3 cm. per second). In clinically improved and stable patients, amyl nitrite inhalation resulted in increased intensity of the commonly heard systolic ejection type murmur at the left sternal border and echocardiographic evidence of further narrowing of the outflow tract measured between the interventricular septum and the anterior portion of the stent. Calcific homograpft stenosis was associated with a decreased diastolic stent slope (0.4 cm. per second) and increased echo density from the tissue leaflets. Thrombus formation on the sewing ring caused fatal inflow occlusion in 2 patients. The condition was characterized by an echocardiogram showing decreased ratio of internal-to-external stent diameter, 0.47 (normal range 0.56 to 0.74), decreased diastolic stent slope, and decreased leaflet excursion.

Neoplastic pericardial disease.

The spread of metastatic cancer to the pericardium is the most common cause of cardiac tamponade in medical inpatient settings. Lung cancer, breast cancer, and the hematologic malignancies account for some three quarters of the cases. Occasionally, usually in lung cancer, the pericardial involvement is the first clinical presentation of the neoplastic disease. Differential diagnosis includes radiation pericarditis and cardiac toxicity from chemotherapeutic drugs, as well as any of the causes of pericardial disease in patients without neoplasm. Idiopathic nonneoplastic, noninflammatory pericardial effusion is surprisingly common in cancer patients. The initial cardiac tamponade may be managed with either needle tap or subxiphoid pericardiostomy. Pericardiocentesis, performed with echocardiographic guidance and followed by percutaneous catheter drainage for several days, is safe and effective in neoplastic pericardial effusion. It may be the only local therapy that is needed. Further local treatment, for those patients who develop recurrent cardiac tamponade after an initial drainage procedure, may include tetracycline sclerosis of the pericardial space, instillation of cancer chemotherapeutic agents, radiation therapy, and pericardiectomy. No controlled clinical trials of these methods of treatment are available. The choice of therapy is based on various considerations in individual patients, particularly the patient's general condition and the likelihood of a long-term response to treatment of the systemic neoplastic disease.