Magnitude of mitral valve closure plays a pivotal role in enhancing the forward blood flow during cardiac massage in dogs with ventricular fibrillation.

Motion of mitral valve during cardiac massage was examined using beagle dogs with ventricular fibrillation (n=4). Active compression-decompression cardiac massage (ACD-CM) exhibited greater peak aortic pressure than standard cardiac massage (S-CM), reverse of which was true for peak pulmonary capillary wedge pressure in each animal. Accordingly, peak aortic pressure was greater than peak pulmonary capillary wedge pressure with ACD-CM, whereas its reverse was true with S-CM. Transesophageal echocardiography revealed that mitral valve was incompletely closed with S-CM with showing regurgitation. The valve was more effectively closed during ACD-CM. These results indicate that effective closure of mitral valve during cardiac massage may increase forward blood flow, supporting "cardiac pump theory" rather than "thoracic pump theory" as a principle in dogs.

Thoracic massage permits use of echocardiography in unanesthetized rats.

PURPOSE: The objective of the study reported here was to investigate whether massage-like stroking of the thorax and cranial portion of the abdomen might relax unanesthetized rats sufficiently to permit in vivo echocardiography. METHODS: Nine-month-old spontaneously hypertensive rats (SHR) were first conditioned to being held by hand for 10 to 15 min twice a day for seven to 10 days. During each session, the animal was placed in supine position, and the thorax and cranial abdominal area were gently stroked (approx. 5 cm/s, 12 to 14 times/min). After the conditioning period, echocardiography was initiated. We obtained serial transthoracic two-dimensional (2-D) and M-mode echocardiograms from nine-month-old SHR that were treated with isoproterenol (60 mg/kg of body weight, s.c., x 1, followed by 30 mg/kg/d x3), and from old (20 to 24 months old) SHR, studied when labored breathing, suggestive of heart failure, was evident (SHR-F). Measurements included end-diastolic volume (EDV) and end-systolic volume (ESV). RESULTS: In the isoproterenol-treated SHR, mean +/- SD echocardiographically derived EDV (2-D, 0.29 +/- 0.05; M-mode, 0.28 +/- 0.01 ml) was not significantly different from volume at necropsy (0.33 +/- 0.04 ml). Measurements of EDV and ESV by use of M-mode and 2-D echocardiography were significantly correlated (EDV R2 = 0.48, P = 0.05; ESV R2 = 0.39, P = 0.02). Echocardiography revealed pleuropericardial effusions (4/6), atrial thrombi (5/6), and left and right ventricular enlargement (6/6). The EDV and ESV were increased fivefold (P < 0.01) and threefold (P < 0.05), respectively, versus values for SHR not in heart failure (SHR-NF). Left ventricular ejection fraction of hearts from SHR-F was markedly decreased, compared with that in SHR-NF (44 +/- 7 versus 74 +/- 2%, respectively; P < 0.05). The presence or absence of left atrial thrombi and fluid in the thoracic cavity was confirmed at necropsy in SHR-F and SHR-NF. CONCLUSION: Thoracic massage permits use of echocardiography in unanesthetized rats, thereby providing a simple, non-invasive technique for assessment of cardiac structure and function in rats without the potentially adverse effects of anesthesia.

New thoughts on cardiopulmonary resuscitation.

The results of cardiopulmonary resuscitation (CPR) have been distressingly poor when one considers the amount of research in this field since 1960. Accordingly, some improvements to present protocols have been suggested. Some of the suggestions can be applied by practicing veterinarians to increase the success rate for external chest massage. In addition, veterinarians are encouraged to switch to internal cardiac massage early in the resuscitation period.

[Recent insights into the possibilities of resuscitation of dogs and cats]. / Huidige inzichten in de mogelijkheden van reanimatie bij de hond en de kat.

This article reviews the present state of the art of resuscitation of dogs and cats. The purpose of resuscitation is to revive animals so that the vital functions resume together with a normal brain function. Resuscitation must be started as soon as the cardiopulmonary arrest has been confirmed. Adequate ventilation and effective circulation to the most vital body organs, the heart and the brain, have the highest priority. They can be achieved by endotracheal intubation, artificial ventilation with 100% oxygen and rhythmic compression of the closed chest or direct cardiac massage following thoracotomy. Medical therapy is an important part of resuscitation. In the absence of a central venous route, deep endotracheal administration is the preferred method of administration. Most medications can be administered through the endotracheal tube in this fashion.

Use of a modified open patch-graft technique and valvulectomy for correction of severe pulmonic stenosis in dogs: eight consecutive cases.

A modified open patch-graft technique was used to correct congenital pulmonic stenosis in 8 dogs. Pulmonary valve dysplasia was moderate to severe in all cases, based upon clinical and echocardiographic criteria, and 3 dogs were in right-sided congestive heart failure at the time of surgery. Seven of the 8 dogs survived the surgery. One surviving dog displayed cerebral cortical dysfunction, the remaining 6 had no detectable neurological sequelae. Right ventricular failure was alleviated in all 7 surviving dogs, but right ventricular dilatation persisted post-operatively. Pulmonary valvulectomy and open patch-grafting provides an effective means of alleviating signs of congestive heart failure caused by pulmonary valve dysplasia, even in the presence of severe infundibular hypertrophy and dynamic outflow obstruction.

External cardiovascular resuscitation of the anesthetized pony.

External cardiac massage and concomitant respiratory support were used successfully 6 of 8 anesthetized ponies sustaining unexpected cardiac arrest while being used in a study of shock. Approximately 20 thoracic compressions/min maintained systolic and diastolic aortic blood pressures in excess of 50% of the corresponding base-line values in 5 ponies. The high success rate was attributed to early recognition of the problem, the small size of the patient, and the relatively short duration of cardiopulmonary resuscitation (average, 2.9 minutes). It was concluded that external cardiac message can be effective for cardiopulmonary resuscitation in selected equine patients that have sustained cardiac arrest.