Melvin Kahn

Treatment of supraventricular tachycardias with catheter and permanent pacemakers

Abstract Temporary catheter and then permanent cardiac pacing were successfully used to treat supraventricular tachycardias in a patient with chronic sinus and nodal bradycardia complicated by paroxysmal nodal tachycardia and atrial flutter. Ventricular pacing with retrograde conduction abolished the nodal tachycardia and facilitated the treatment of the atrial flutter.

Wolff-Parkinson-White syndrome: A vectorcardiographic, electrocardiographic and clinical study

Abstract 1. 1. Thirty-eight cases of Wolff-Parkinson-White syndrome are analyzed by vectorcardiographic and electrocardiographic correlative study. 2. 2. Although electrocardiographic grouping into types A and B has been challenged as being unnecessary, vectorially the delta vector or QRS sE loops in the horizontal plane fell into two distinct quadrants which we have designated as groups A and B, respectively. In group A the delta vector is anteriorly oriented, and in the +30 degrees and +120 degrees quadrant in the horizontal plane. In group B the delta vector is oriented to the left, and in the −60 degrees to +30 degrees quadrant in the horizontal plane. In group A the QRS sE loop was more commonly inferiorly oriented, whereas in group B the QRS sE loop was more commonly superiorly oriented, although there was overlap. 3. 3. The delta portion of the QRS sE loop was usually oriented in the same direction as the remainder of the QRS sE loop, and determined the spatial orientation of the QRS sE loop. 4. 4. Some of the clinical features of this syndrome are briefly discussed, including the association with paroxysmal tachycardia and atrial fibrillation or flutter. 5. 5. The pitfalls in the diagnosis of myocardial infarction in the presence of this syndrome are stressed. 6. 6. In patients whose conduction became normal the QRS sE loops that were observed were usually greatly dissimilar from those recorded during WPW conduction. This observation, in conjunction with the electro-kymographic and catheterization studies of others which demonstrated no abnormal asynchronysm of ventricular contraction, suggests to us that early excitation of just one ventricle cannot take place, and that therefore not only the initial portion of spread of excitation is anomalous, but also the entire conduction through both ventricles may be anomalous.

Effects of ryanodine in normal dogs and in those with digitalis-induced arrhythmias: Hemodynamic and electrocardiographic studies☆

Abstract The hemodynamic and electrocardiographic effects of ryanodine were studied in normal anesthetized dogs and in those with digitalis-induced ventricular arrhythmias. The electrocardiographic effects of ryanodine may be divided into three sequential overlapping phases: (1) Peaking of the T waves, broadening and flattening of the P waves, loss of the P-R segment, S-T segment depression and sinus slowing; (2) complex paroxysmal supraventricular tachycardias without impairment of A-V conduction; (3) prolonged periods of sinoatrial arrest or bradycardia with A-V block. In all phases the QRS complex was unchanged, and ectopic ventricular beats did not occur. Ryanodine reversed digitalis-induced ventricular arrhythmias in the dog by suppressing ventricular pacemakers without prolonging intraventricular conduction. The conversion to sinus rhythm was usually transient, since complex supraventricular arrhythmias probably attributable to the combined action of the two drugs often supervened. A profound negative inotropic action of ryanodine, previously demonstrated in vitro, was shown to be significant in the intact animal. This was manifested by a significant fall in the cardiac output and a rise in the left ventricular end-diastolic pressure prior to a change in rate or rhythm. The electrocardiographic and negative inotropic effects of ryanodine are similar to those of hyperkalemia, although it is probable that all the observed changes cannot be explained by this mechanism. Since the negative inotropic effects of ryanodine were observed at the same dose required for reversal of the digitalis-induced ventricular arrhythmia, it is likely that the toxicity of this drug precludes its use in the treatment of digitalis intoxication in human beings. However, it may be useful for the study of myocardial metabolism and function.

The vectorcardiogram and electrocardiogram before and after valvulotomy for pulmonic stenosis

Abstract 1. 1. The electrocardiograms and vectorcardiograms of twelve patients were correlated with hemodynamic data before and after pulmonic valvulotomy. All patients preoperatively had a severe degree of pulmonic stenosis, with right ventricular systolic pressures of 99 mm. Hg or higher. 2. 2. Preoperatively, neither the level of right ventricular systolic pressure nor the systolic gradient across the pulmonic valve correlated closely with the components of the electrocardiogram or configuration of the QRSsE loop of the vectorcardiogram. Inverted T waves in the precordial leads and the greatest rightward deviation of the electrical axis tended to be present in patients with the highest right ventricular pressures. 3. 3. Following surgery, changes in the electrocardiogram and vectorcardiogram in any given case accurately reflected changes in the right ventricular load. Incomplete regression of electrocardiographic or vectordardiographic signs of right ventricular hypertrophy in our series indicated either an inadequate period of observation, incomplete correction of the stenotic lesion, or the presence of other hemodynamically significant defects. This suggests that serial cardiographic studies postoperatively provide a readily available method for evaluating the results of pulmonic valvulotomy.

The role of bradycardia in the retention of sodium and water in complete heart block with and without heart failure in human beings

Abstract 1. 1. The relative contribution of bradycardia in causing heart failure in patients with complete and advanced heart block was assessed by studying the effect of increasing the cardiac rate by an internal pacemaker. 2. 2. The ability to excrete graded loads of sodium was measured in 4 patients with complete or advanced heart block. Maximal sodium excretory capacity and the presence or absence of heart failure, after the stress of sodium-loads, during bradycardia, and after increasing the cardiac rate, were determined. 3. 3. One patient who had no heart failure despite cardiac rates between 30 and 40 could ingest and excrete 26 Gm. of sodium chloride daily without the development of heart failure. A second patient without heart failure had a maximal excretory capacity of 16 Gm. daily and exhibited symptoms and signs of heart failure with intakes in excess of this quantity. In the other 2 patients with heart failure at the time of hospitalization, maximal daily excretory capacity for sodium was 35 to 55 mEq. 4. 4. After cardiac rates were increased to normal with an artificial pacemaker, maximal excretion of sodium increased significantly. In the 2 patients with heart failure at slow idioventricular rates, the decompensation was eliminated or ameliorated. Although the maximal excretion of sodium was increased, it was still below normal in the latter 2 patients. 5. 5. The glomerular filtration rate was diminished in varied degree and correlated with the capacity for sodium excretion and the presence of absence of heart failure in each of the patients.

Experimental Large-Volume Hemodilution

1. Large-volume hemodilution was experimentally performed with a standardized reservoir arteriovenous fistula preparation in which intra- and extracorporeal volumes were kept constant. Vasopressors, buffers, hypothermia, and overinfusion were not employed.2. Control studies with 10 ml/kg of various diluents revealed hemodynamic, volumetric, and biochemical stability of the experimental preparation.3. Homologous blood exchange (100 ml/kg) with heart worm-free donors and recipients caused arterial hypotension, hepatic and pulmonary congestion, and depressed renal function.4. All diluents tested produced hypotension and metabolic acidosis under the conditions of the experiment when used in amounts approximately equivalent to canine blood volumes. Ten per cent of the diluted animals expired from shock.5. Blood pressure was initially better sustained with low molecular weight dextran, dextrose-Ringers-albumin, and dextrose-Ringers solutions, but the effect was short lived.6. Cardiac outputs and total blood volumes did not change appreciably during the exchange infusions. Hematocrit changes reflected maintenance of intravascular volume. Peripheral resistance fell significantly, shortly after the onset of constant volume exchange.7. Osmolality and oncotic activity of the diluents showed no clear-cut relationship to over-all stability of the infused animals.8. The clinical advantages of hemodilution have been well established. Hemodynamic, volumetric, and biochemical differences between clinical perfusions and the experiments outlined herein attest to the roles of over-infusion, buffering, and hypothermia in ameliorating the experimentally observed sequelae.9. The data suggest that the search should be continued for a more ideal blood substitute, as well as for low-prime, high-flow extra-corporeal systems.

Systolic triple rhythms

Abstract 1. 1. The records of sixty-four cases of systolic triple rhythm have been reviewed. The presence or absence of cardiovascular disease and the various characteristics of these sounds were evaluated. 2. 2. Systolic triple rhythms are probably more frequently present than generally suspected and may be heard in a wide variety of cardiac and extracardiac diseases. 3. 3. Early systolic clicks are ejection sounds and are found in patients with congenital and acquired lesions of the semilunar valves and great vessels and are usually associated with a murmur. 4. 4. Mid- or late systolic sounds may or may not be associated with a murmur and are usually not observed in patients with cardiovascular disease. 5. 5. With a thorough understanding of the characteristics of systolic sounds, their significance may be correctly interpreted.

The Homologous Blood Syndrome IV. Effects of Autologous and Homologous Plasma, Saline and Heartworm-Free Homologous Blood*

Abstract 1. 1. The homologous blood syndrome occurs in the absence of heartworms, having been demonstrated in 11 of 15 dogs undergoing constant volume exchange of homologous blood (100 ml./kg.) devoid of D. immitis microfilariae and adult worms. 2. 2. Neither buffering nor high carbon dioxide tension prevented the development of severe hypotension and metabolic acidosis during exchange of saline (100 ml./kg.) in ten experiments. 3. 3. Constant volume exchange (100 ml./kg.) of stored dialyzed autologous plasma caused no severe hypotension, acidosis, nor demonstrable allergic reactions. Homologous plasma resulted in an unpredictable occurrence of severe hypotension and intense urticaria during the exchange infusions. 4. 4. The data suggest that continuing studies with autologous plasma may provide insight into the development of a better perfusate for extracorporeal circulation. The significance of the hypotensive and allergic reactions with homologous plasma requires further investigation.