Biomedical subjects
Publications and source records attributed to P Rakovec.
A patient with spontaneous left-sided pneumothorax and unusual, phasic voltage variations in the electrocardiogram (ECG), which fluctuated depending on respiration, was observed. After intercostal tube drainage, these variations disappeared. The respiratory changes in the thorax seem to be a cause of these ECG findings.
Long-standing ventricular tachycardia (VT) and supraventricular tachycardia (SVT) can produce a reversible left ventricular dysfunction. The onset of cardiomyopathy and the severity of posttachycardic changes depend at least on three parameters of tachycardia, including its type (VT or SVT), rate and duration. Ten dogs (beagles) were paced at 180 beats/min for 3 weeks. Two pacing modalities, supraventricular and ventricular, were used in each dog. In half of them, the study was started by ventricular, and in the other half by supraventricular high-rate pacing. The alternate pacing modality was applied after complete recovery of left ventricular function. Ventricular function and morphology were evaluated by radionuclide ventriculography, echocardiography and Swan-Ganz catheterisation. Posttachycardic changes were studied in sinus rhythm after cessation of pacing. Left ventricular ejection fraction (LVEF) fell significantly after either type of tachycardia (SVT: 53 +/- 5%, VT: 48 +/- 7%, P < 0.05) compared with baseline values (69.5 +/- 2.3%). Significant increases (P < 0.05) in end-systolic (SVT: 2.1 +/- 0.3 cm, VT: 2.4 +/- 0.2 cm vs. 1.6 +/- 0.3 cm) and end-diastolic dimensions (SVT: 3.0 +/- 0.3 cm, VT: 3.3 +/- 0.4 cm vs. 2.7 +/- 0.3 cm) indicated ventricular dilation in paced animals. Left ventricular pulmonary capillary wedge pressure increased significantly after either type of tachycardia as compared with baseline values (SVT: 7.5 +/- 1.2 mmHg, VT: 8.4 +/- 1.1 mmHg vs. 1.9 +/- 1.5 mmHg, P < 0.05); the difference between tachycardias was not significant. The present study demonstrates that chronic SVT and VT result in left ventricular dysfunction in a relatively short time, even if the heart rate is not very high. Deterioration of left ventricular ejection fraction and dilation of the left ventricle are more marked in chronic VT than in chronic SVT.
Shifts in sinus node pacemaker complex may occur spontaneously, but occurrence of clinically relevant shifts is very rare. In this report, three patients (2 are siblings) with a history of palpitations and nearly permanent shifts in sinus node pacemaker complex are presented. Often, but not always, the pacemaker shifts followed spontaneous sinoatrial exit blocks. The shifts were probably related to varying vagal tone, since they were eliminated by atropine and exercise. The experience with these patients suggests that sinus pacemaker shifts can be a cause of symptomatic nonrespiratory sinus arrhythmia. A 4-year follow-up period showed no changes in symptoms or in heart rhythm; therefore, a benign course of the disease can be expected.
A female with advanced aortic valvular stenosis and moderate right coronary artery disease experienced an exertional syncope during 24-h ambulatory electrocardiographic monitoring. A progressive bradycardia with 90-s sinus node arrest (cardio-inhibitory response) and premonitory angina pectoris with significant ST segment changes were demonstrated. Our report supports the concept of a neurocardiogenic (vasovagal) mechanism of exertional syncope in patients with aortic stenosis. The predominant left ventricular inferior-wall myocardial ischaemia in our patient might be an additional stimulus to left ventricular mechanoreceptors, resulting in a profound cardio-inhibitory response.
Emery-Dreifuss muscular dystrophy is an X-linked recessive myopathy. Its progression is slow, and it rarely leads to cessation of walking; therefore, it has often been called "benign." On the other hand, cardiac involvement is often severe and sudden death is not uncommon. We describe a family with four affected males, two of whom died suddenly. The case of an affected man with first-degree AV block, incomplete right bundle branch block, and left anterior fascicular block is described in detail. The prophylactic insertion of a diagnostic pacemaker enabled us to follow the progress of conduction disturbances without leaving the patient unprotected. While AV and intraventricular conduction defects were more prominent before pacemaker implantation, sinus node dysfunction became more important during the follow-up.
A patient who had undergone myocardial revascularization with a saphenous vein graft to the left anterior descending artery and a left internal thoracic (mammary) artery graft to the 1st diagonal branch presented with an unusual form of subclavian steal syndrome. Occlusion of both the left subclavian and the left anterior descending arteries caused retrograde flow through the internal thoracic artery to the distal subclavian artery; the blood flow was supplied by the vein graft via the distal left anterior descending artery and diagonal branch.
A 48-year-old man with Wolff-Parkinson-White syndrome and poorly tolerated atrial fibrillation underwent surgical dissection of an accessory pathway. After operation electrocardiogram revealed a very unfavorable outcome: sinus rhythm with persistence of delta waves alternated with sequences of complete atrioventricular block. Therefore, an early reoperation was planned. Fortunately, in the next days conduction through the accessory pathway and signs of atrioventricular block disappeared. Complete cure was observed during long-term follow-up.
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A family with the Romano-Ward syndrome is described. A 28-year-old woman had episodes of syncope due to self-terminating ventricular tachycardia torsades de pointes. During lidocaine treatment she developed a sustained ventricular tachycardia and cardiopulmonary resuscitation was necessary. Propranolol reduced ventricular ectopic activity, but the QTc interval remained prolonged. A "threshold" in QT duration for the generation of complex ventricular arrhythmias was observed in the patient. There were no late ventricular potentials noted in the signal averaged ECG in the patient and in members of her family.
A patient with congestive cardiomyopathy, induced by ventricular tachycardia, is presented. The patient had chronic ventricular tachycardia, which persisted 4 months and was eventually successfully treated by an antitachycardia pacemaker. A severe left ventricular dysfunction persisted after treatment for some days and then gradually resolved. After 3 months the indices of left ventricular function returned to normal values. The tachycardia-induced ventricular dysfunction seems to be a reversible disorder.
A patient with hypertensive heart disease, in whom atrial premature beats with a decrease in the amplitude and widening of his bundle potential, prolongation of the H-V interval, and right bundle branch block pattern suggested intrahisian longitudinal dissociation, is described.
The case of a 55-year-old woman with primary pulmonary hypertension is described who developed 2 hours after sublingual administration of a 10 mg capsule of nifedipine a severe rise in pulmonary arterial and right atrial pressures accompanied with dyspnoea and cyanosis. The event lasted for two hours and subsided without intervention. With repeated nifedipine intake in the form of orally administered slow-release tablets no complications occurred. The authors ascribe the marked rise in pulmonary vascular resistance to rapid reduction of plasma nifedipine concentration after sublingual administration, due to a faster drug resorption compared to oral intake. The necessity of cautious introduction of vasodilating drugs in pulmonary hypertension and of gradual dosage increase is stressed.
The case of a 44-year old man, never exposed to asbestos, who died from a pericardial mesothelioma is described. The diagnosis was made by surgical examination. Two weak transient episodes of amelioration, the first accomplished with pronison administration and the other one by radiotherapy, were registered.
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Sudden onset of atrial fibrillation can be very dangerous in patients with WPW syndrome, because it may result in high ventricular rate. The ventricular rate depends upon the length of the effective refractory period (ERP) of the accessory pathway. It is appropriate, therefore, to test newer antiarrhythmic agents on their effect on the ERP of the accessory bundle. 13 patients underwent the studies. Ethmozin was given intravenously 1 mg/kg body weight. The ERP increased significantly after Ethmozin (p less than 0.05). The increase was more prominent in those patients who had longer basal values of ERP (greater than 300 ms), as compared with the patients with shorter values (less than 300 ms); the latter revealed at most a slight lengthening of the ERP. Ethmozin exerts a favourable effect on the accessory pathway, however, the effectiveness of this substance is insufficient in patients, who are at risk because of a very short ERP.
The sequence of ventricular contraction was studied by radionuclide phase imaging in 25 patients with Wolff-Parkinson-White syndrome. The studies were performed when no signs of precontraction were present in the electrocardiogram; in these cases pre-excitation was either intermittent or suppressable by injection of ajmaline. In 11 of the 16 patients with free wall accessory pathways, precontraction could be detected in spite of electrocardiographically absent pre-excitation. Discrete precontraction was seen also in 2 of the 9 patients with paraseptal accessory pathways. We conclude that antegrade conduction through the accessory pathway does not need to be completely blocked if signs of pre-excitation are absent on the electrocardiogram, and that phase imaging is, at least in some patients (especially those with free wall accessory pathways), a more sensitive technique for detection of pre-excitation (precontraction) than the electrocardiogram.
The Kearns-Sayre syndrome is an uncommon disease, characterized by the triad of external ophthalmoplegia, retinitis pigmentosa, and heart block. Cardiac manifestations of this syndrome in a 31-year-old man are presented. Electrocardiogram revealed intermittent left bundle branch block and right bundle branch block with left anterior hemiblock. His bundle recording disclosed a prolonged HV interval. Clinical features of the syndrome are discussed and other published cases reviewed.
Coinciding left bundle-branch block and Wolff-Parkinson-White syndrome type B, a very rare electrocardiographic occurrence, was found in a patient with dilated cardiomyopathy. Electrophysiologic study revealed eccentric retrograde atrial activation during ventricular pacing, suggesting right-sided accessory pathway. At programmed atrial pacing, effective refractory period of the accessory pathway was 310 ms; at shorter pacing coupling intervals, normal atrioventricular conduction with left bundle-branch block was seen. Left bundle-branch block was seen also with His bundle pacing. Radionuclide phase imaging demonstrated right ventricular phase advance and left ventricular phase delay; both right and left ventricular phase images revealed broad phase distribution histograms. Combined electrophysiologic and radionuclide investigations are useful to disclose complex conduction abnormalities and their mechanical correlates.