Early anthracycline cardiotoxicity

Eight patients in whom cardiac dysfunction developed within four weeks of receiving their first or second course of daunorubicin or doxorubicin are described. Four patients presented with pericarditis; three of these four had evidence of myocardial dysfunction. Histopathologic analysis of these patients was consistent with an acute myocyte damage and secondary inflammatory process. An additional group of four patients presented with symptoms and signs of heart failure. These patients were either elderly or had evidence of previous cardiac disease. One of these patients suffered a myocardial infarction 24 hours after receiving 60 mg/m2 of daunorubicin; earlier doses in the same course had been associated with evidence of myocardial ischemia. We conclude that anthracycline antibiotics may manifest clinically significant cardiotoxicity at total cumulative doses much less than have been associated with chronic cardiomyopathy.

Cardiac biopsy evidence for a cardiomyopathy associated with symptomatic mitral valve prolapse

Right ventricular endomyocardial biopsy was performed in 14 patients with mitral valve prolapse to determine the existence of an associated cardiomyopathic process. All 14 patients had echocardiographic, angiographic or auscultatory evidence of mitral valve prolapse, and all were symptomatic. The group had a high incidence rate of conduction system abnormalities (50 percent) and arrhythmias (64 percent), but only one patient had a significant hemodynamic abnormality. Light microscopy revealed an increase in endocardial and interstitial fibrosis in eight patients (57 percent). Electron microscopy, performed in 11 patients, showed mitochondrial degenerative changes in all 11. Nuclear chromatin clumping, intracell edema and myocyte degeneration were frequently present. It is concluded that endomyocardial and myocardial abnormalities exist in some symptomatic patients with idiopathic mitral valve prolapse.

Cardiac sarcoidosis. Diagnosis with endomyocardial biopsy and treatment with corticosteroids

A 27 year old woman was hospitalized for progressive dyspnea, fatigue and retrosternal chest pain. She had progressive cardiac enlargement with clinical and laboratory confirmation of a dilated cardiomyopathy. Transvenous percutaneous right ventricular endomyocardial biopsy yielded a specimen showing a noncaseating granuloma. The patient's dyspnea responded dramatically to steroid therapy with corresponding improvement in radiographic and echographic measures of ventricular performance. This case illustrates the problem of diagnosing cardiac sarcoidosis when there is no apparent evidence of other organ involvement.

Clinical spectrum of anthracycline antibiotic cardiotoxicity

Anthracycline derivatives may produce early or late cardiotoxic reactions in man. Early effects include: (a) pericarditis-myocarditis which can affect patients with no previous history of cardiac disease and which carries a high mortality rate ( approximately 20%); (b) left ventricular dysfunction which may lead to clinically significant heart failure in patients with limited cardiac reserve; and (c) arrhythmias, the most common of which is sinus tachycardia. Symptomatic supraventriclar tachycardia, heart block, and ventricular arrhythmias can occur, however, and may reflect primary effects on cardiac muscle or the conduction system. Late effects of anthracyclines are directly related to the degree of associated myocyte damage and include subclinical left ventricular dysfunction and overt heart failure. The implications for prognosis and further treatment are discussed for each of these entities and a common pathogenetic mechanism is proposed.

Electrophysiological effects of edrophonium in the innervated and the transplanted denervated human heart

In order to determine the mechanism of action of edrophonium on the cardiac conduction system, we used His bundle recording and pacing techniques to examine the electrophysiological effect of edrophonium in 6 patients undergoing diagnostic evaluation for coronary artery disease and in 9 cardiac transplant recipients who were free of acute graft rejection. After control measures were made of sinus cycle length, conduction intervals, and conduction system refractory periods, edrophonium was administered by constant intravenous infusion, and all electrophysiological measurements were repeated. In the normally innervated patients, edrophonium significantly increased sinus cycle length from 778 +/- 21 ms to 883 +/- 36 ms (P less than 0.01), AH interval from 88 +/- 11 ms to 100 +/- 12 ms (P less than 0.01), and AV nodal functional refractory period from 351 +/- 44 ms to 391 +/- 36 ms (P less than 0.05). In the patients with transplanted hearts, edrophonium had no electrophysiological effect other than increasing the cycle length of the remnant recipient atrium from 722 +/- 21 ms to 798 +/- 31 ms (P less than 0.01). We conclude that the electrophysiological effects of edrophonium in man are mediated primarily through autonomic innervation of the heart.

Anthracycline cardiomyopathy monitored by morphologic changes

Seventy-six endomyocardial biopsies obtained from 60 patients receiving adriamycin (ADM) and other anthracycline analogs were studied. The biopsies were studied by light and electron microscopy. Two main types of myocyte degeneration were consistently present, the lesions were focal, and inflammatory infiltrate was absent. The severity of pathologic changes was graded on a scale from 0 (normal) to 3 (marked abnormality). Twelve patients receiving previous mediastinal irradiation (600-5700 rads) showed a mean pathology grade (2.0 +/- 0.89) that was significantly higher than in those patients receiving a comparable dose of ADM but who were not irradiated (1.18 +/- 0.23) (P less than 0.01). This study indicated that radiation, even if remote, enhances ADM-induced cardiotoxicity and evokes a "recall" phenomenon of latent acute irradiation changes. Our data suggest that a specific, progressive, subclinical injury to the heart occurs with anthracycline therapy that cannot be detected reliably by conventional tests. Anthracycline-induced cardiotoxicity in rabbits, monkeys, and dogs shows the same basic cellular lesions as in man. The analogs, adria-DNA and rubidazone, also show lesions similar to those produced by ADM in the human heart. The endomyocardial biopsy is a reliable method for monitoring cardiac damage due to anthracyclines in man.

Invasive and noninvasive methods of assessing adriamycin cardiotoxic effects in man: superiority of histopathologic assessment using endomyocardial biopsy

Endomyocardial biopsies and cardiac catheterizations were performed in 55 patients treated with adriamycin (ADM). Eleven patients underwent serial invasive studies. In addition, most of these patients had systolic time interval determinations, echocardiograms, and electrocardiograms at the time of catheterization. The relationship of these various tests to cumulative dose of ADM and to the incidence of cardiac dysfunction was analyzed. Only pathologic assessment of ADM-induced myocardial damage showed a progressive stepwise increase in severity at successively higher doses of ADM. In addition, the incidence of myocardial dysfunction correlated well only with pathologic findings on biopsy. We conclude that standard noninvasive methods of assessing ADM cardiotoxicity are inadequate and that histopathologic assessment by means of endomyocardial biopsy is a valuable, reliable, and accurate technique.

Depressant effect of digoxin on atrioventricular conduction in man

We examined the effect of chronically administered digoxin on atrioventricular (A-V) conduction in nine cardiac transplant recipients. We assessed A-V conduction by measuring the duration from the pacing stimulus to the onset of the QRS complex (S'R interval) and by determining the occurrence of Wenckebach periodicity during rapid atrial pacing. We made measurements during a control period and during a period of digoxin administration of up to 37 days. During the digoxin period, the cycle length at which Wenckebach block occurred was prolonged by 14% of the control value and the S'R interval was significantly prolonged at paced rates of 110 beats per minute and faster. After digoxin was discontinued, the Wenckebach periodicity and S'R interval returned to control values. Atropine and propranolol did not alter digoxin's effect on A-V conduction. We conclude that digoxin exerts a direct (or non-neurally mediated) depressant effect upon A-V conduction in man, although the stress of tachycardia is necessary to demonstrate the effect.

Electrophysiologic findings in patients with idiopathic hypertrophic subaortic stenosis

Thirteen patients with catheterization-proved idiopathic hypertrophic subaortic stenosis underwent intracardiac electrophysiologic study. There was a large incidence of arrhythmias and a strikingly large incidence of conduction system abnormalities among these patients. The P-A and A-H intervals were normal in all patients. Atrial pacing resulted in Mobitz type 1 block proximal to the His bundle at an abnormal rate (less than 140/min) in 2 of 12 patients (17 percent). H-V intervals were prolonged (greater than 50 msec) in 10 of 12 patients (83 percent) and were greater than 60 msec in 7 patients (58 percent). The atrial effective refractory period was prolonged in 3 of 12 patients and was markedly prolonged in 1 of them. Effective refractory period of the atrioventricular (A-V) node, determined in five patients, was prolonged in three. Dual responses of the A-V node to atrial extrastimuli were found in seven patients. Dual A-V nodal repsonses were evoked with propranolol in three patients and persisted in the other four patients with dual responses despite propranolol administration.

Techniques for right and left ventricular endomyocardial biopsy

Right ventricular endomyocardial biopsy using percutaneous right internal jugular approach proved a safe and easily performed technique in more than 1,300 procedures. Adequate tissue was obtained in more than 98 percent of patients and morbidity rate was remarkably low. Other approaches to the right ventricle may be used, but retrograde left ventricular endomyocardial biopsy appears to be the safest and most reliable alternative to transjugular right ventricular biopsy. The safety and success of the techniques for right and left heart biopsy described depend on meticulous attention to methodologic detail.

Clinical electrophysiologic effects of tocainide

The electrophysiologic properties of tocainide were evaluated by electrophysiologic studies in 11 patients before, during and after a constant intravenous infusion of the drug for 15 minutes. Peak plasma tocainide concentrations averaged 11.0 +/- 1.7 microgram/ml (SEM), range 3.7 to 22.7. AH, HV, QRS, QTc and RR intervals were measured every 5 minutes during sinus and atrial-paced rhythms and showed small changes which were not statistically significant for HV and QRS. Mild shortening of RR was significant (P less than 0.05) at 15 minutes only. AH tended to increase slightly for spontaneous (but not paced) rhythm, becoming significant at 15 minutes only (P less than 0.05). QTc decreased slightly, a change which was significant (P less than 0.05) for paced but not spontaneous rhythm. A progressive rise in mean arterial pressure occurred during infusion and persisted through 30 minutes (P less than 0.001). Comparison of electrophysiologic studies at 0 and 30 minutes showed decreased in mean effective refractory periods of atrium, A-V node, and right ventricle by 17, 22, and 23 msec, respectively (P less than 0.05, 0.01, 0.01). Functional refractory period of the A-V node showed an average decrease which was not significant. Sinus node recovery time and Wenckebach cycle length were unchanged. The drug was well tolerated in all 11 patients. Hypotension in a twelfth patient may or may not have been drug related. These results obtained at therapeutic plasma concentrations suggest qualitative similarities between the conduction system effects of tocainide and those published for lidocaine.

Successful treatment by overdrive pacing of recurrent quinidine syncope due to ventricular tachycardia

A 54 year old patient who experienced recurrent ventricular tachycardia subsequent to quinidine administration for conversion of atrial fibrillation is described. Over a 10 hour period, 25 sustained episodes of ventricular tachycardia occurred for which electrical cardioversion was required in addition to numerous self-terminating paroxysms. Medical therapy with lidocaine, procainamide and propranolol was unsuccessful in controlling the arrhythmia. However, placement of a transvenous right ventricular pacemaker with overdrive pacing at a rate of 110 beats/min abrupty terminated all further ventricular ectopic activity during the period of quinidine elimination. Temporary overdrive pacing may be the treatment of choice for refractory, recurrent, ventricular tachycardia associated with quinidine therapy.

Doxorubicin cardiomyopathy: evaluation by phonocardiography, endomyocardial biopsy, and cardiac catheterization

Right ventricular endomyocardial biopsy, right heart catheterization, and systolic time intervals were done in 33 adult patients receiving doxorubicin (AdriamycinTM). Doxorubicin administration was associated with a dose-related increase in the degree of myocyte damage, and 27 of 29 patients biopsied at doses greater than or equal to 240 mg/m2 had doxorubicin-associated degenerative changes identified on biopsy. The pre-ejection period to left ventriculr ejection time ratio (PEP/LVET) showed a threshold phenomenon and did not begin to increase until a total dose of 400 mg/m2 had been reached. Seven patients with catheterization-proven heart failure had a significantly greater amount of myocyte damage on biopsy than dose-matched control subjects (P less than 0.01). Preveious mediastinal radiation appeared to potentiate the doxorubicin-associated degenerative process. Mediastinal radiation and age greater than or equal to 70 years appeared to be risk factors for doxorubicin-associated heart failure. Dose limitation by combined clinical, noninvasive, invasive, and morphologic criteria offered an advantage over empirical dose limitation or dose limitation by PEP/LVET alone.

Methysergide-induced heart disease: a case of multivalvular and myocardial fibrosis

Methysergide (Sansert) is known to cause mitral and aortic valvular fibrosis and dysfunction, but has generally not been known to damage right heart valves or the myocardium, and cardiac fibrosis has not been considered to be a risk if therapy is intermittently interrupted. The woman who is the subject of this case report developed catheterization-proven severe tricuspid and moderate aortic and mitral regurgitation during noncontinuous therapy with methysergide. In addition, right ventricular endomyocardial biopsy revealed extensive endocardial and intramyocardial fibrosis.

Recurrent heat exposure: enzymatic responses in resting and exercising men

Heat acclimatization was induced in a group of healthy male test subjects by repetitive treadmill walking (5.6 km-h-1, 49 degrees/27 degrees C dry/wet bulb, 90 min-day-1, 7 days). A second group of men, paired for maximal O2 consumption and body weight, remained sedentary under identical environmental conditions. Total plasma protein increased significantly after 45 (P less than 0.05) and 90 (P less than 0.025) min of exercise on the first day of heat exposure, yet after 7 days no increments occurred. Even after heat acclimatization was achieved (day 7), plasma levels of creatine phosphokinase increased during the 90-min walk in the heat (time O vs. 90, P less than 0.025), as was also the case on day 1 (P less than 0.05). Levels of lactate dehydrogenase, glutamate-oxaloacetate transaminase, and glutamate-pyruvate transaminase were not significantly affected by exercise in the heat either before or after heat acclimatization. No correlations could be drawn between base-line enzyme levels and state of physical conditioning.

Technetium-99m pyrophosphate myocardial uptake in patients with stable angina pectoris

99m-technetium (Tc) pyrophosphate myocardial scintigrams of 55 patients with stable angina pectoris were compared with those of 13 normal subjects. The mean scintigraphic score, obtained by averaging the blinded interpretations of four readers scoring on an integral scale from 0 to 4, was significantly higher for the patients with angina than for the control subjects (1.36 compared with 0.48, P less than 0.001). Among the patients with angina, those who had a prior myocardial infarction had a higher mean scintigraphic grade than those without a previous infarction (1.73 versus 1.15, P less than 0.005), and the mean grade in both groups was higher than that of control subjects (P less than 0.001). Radionuclide uptake was predominantly diffuse in the patients with angina pectoris (70%), although in those with greater uptake accumulation tended to be localized. Three of the 68 subjects had high levels of radionuclide uptake but no clinical evidence of acute myocardial injury. This study demonstrates that excess myocardial accumulation of 99m-Tc pyrophosphate can occur in patients with stable angina pectoris.

Recurrent tachyarrhythmia associated with a bifocal demand pacemaker

A recurrent tachyarrhythmia complicated the course of a patient with a permanent atrioventricular sequential (bifocal) demand pacemaker. Investigation by intracardiac electrocardiographic studies revealed that the arrhythmia was associated with normally functioning bifocal pacemaker, whose atrioventricular sequential interval approximated the patient's conduction time from atrium to ventricle. The mechanism of initiation and conversion of the arrhythmia was elucidated. Appreciation of this arrhythmia is necessary for appropriate clinical use of a bifocal demand pacemaker.

Hemodynamic effects of intravenously administered quinidine on the transplanted human heart

The acute hemodynamic effects of intravenously administered quinidine were studied in five heart transplant recipients with an anatomically denervated heart. Quinidine, 10 mg/kg body weight, was infused over a 20 minute period, and mild wall left ventricular dynamics were measured with a new technique using metallic markers surgically implanted in the myocardial wall. Heart rate was maintained constant with atrial pacing, and aortic blood pressure was measured through an indwelling catheter. In each patient the hemodynamic responses to quinidine were similar. End-diastolic, end-systolic and stroke volumes decreased by an average of 19, 26 and 18 percent, respectively. Cardiac output decreased by a mean 0.92 liters/min (-18%), and the mean aortic blood pressure decreased by 10 mm Hg (-11%). All of these changes were statistically significant. Three indexes of the contractile state of the left ventricle--mean circumferential velocity, mean systolic diameter shortening and ejection fraction--were not significantly changed. We conclude that quinidine exerts no acute inotropic myocardial effects in the human transplanted heart and that, when given intravenously, its hemodynamic action is most consistent with venodilatation.